Evaporation of inkjet printed pico-liter droplet on heated substrates with different thermal conductivity

In this work, the evaporation phenomena of 20–45 picoliter water droplet (i.e. 50–65 μm diameter) on heated substrates with different thermal conductivity are studied experimentally. The effect of thermal conductivity of substrates and inter-distance between jetted droplets on the evaporation is investigated. In addition, the model to predict evaporation rate of the picoliter droplet on different substrates at a heated condition is developed using approximations for picoliter droplet. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Taewoong Lim received his B.S and M.S. degree in mechanical engineering from Korea University, Seoul, Korea in 2007 and 2009, respectively. His thesis topic was the evaporation of inkjet printed pico-liter droplet and He has been working at Hyundai Motor Company. Jaeik Jeong received his B.S. degree in mechanical engineering from Korea University in 2008. He is currently a M.S. candidate in mechanical engineering at Korea University. Jaewon Chung received his B.S. and M.S. degrees in mechanical engineering from Yonsei University, Seoul, Korea in 1995 and 1997, respectively and Ph.D. degree from University of California, Berkley in 2002. He was postdoctoral associate in Engineering System Research Center at University of California, Berkley in 2002–2004 and had worked in the Center of Micro and Nano Technology at Lawrence Livermore National Laboratory as a visiting collaborator. He is a currently an associate professor at the Department of Mechanical Engineering at Korea University in Seoul, Korea. His research interests include direct writing methods including drop on demand inkjet printing, electrohydrodynamic printing and laser material processing for printing electronics. Jin Taek Chung received his B.S. and M.S. degrees in mechanical engineering from Korea University, Seoul, Korea in 1983 and 1985, respectively and Ph. D. degree from University of Minnesota, U.S.A. in 1992. He is a currently a professor at the Department of Mechanical Engineering at Korea University in Seoul, Korea. His research interests are heat transfer and 3-D flow in gas turbines and thermal management of electronic devices.     

Nondestructive testing and crack evaluation of ferromagnetic material by using the linearly integrated hall sensor array

Magnetic flux leakage testing (MFLT), which measures the distribution of a magnetic field on a magnetized specimen by using a magnetic sensor such as a Hall sensor, is an effective nondestructive testing (NDT) method for detecting surface cracks on magnetized ferromagnetic materials. A scan-type magnetic camera, based on the principle of MFLT, uses an inclined Hall sensor array on a printed circuit board (PCB) to detect small cracks at high speed. However, the wave forms appear in a direction perpendicular to the scan because the sensors are bonded at different gradients and heights on the PCB despite careful soldering. In this paper, we propose linearly integrated Hall sensors (LIHaS) on a wafer to minimize these waves and to improve the probability of crack detection. A billet specimen is used to determine the effectiveness of the LIHaS in multiple crack detection. This paper was recommended for publication in revised form by Associate Editor Joo Ho Choi Prof. Jinyi Lee was born in Korea in 1968. He received the bachelor degree in mechanical design from Chonbuk University, Jeonju, Korea, in 1992. Also he received the master and Ph.D degree in mechanical and aeronautics & space engineering from Tohoku university, Sendai, Japan, in 1995 and 1998, respectively. He was a Researcher from 1998 to 2000 with the Tohoku university, Iwate university, Iwate Techno-Foundation and Saitama university, Japan. From 2000 to 2003, he worked for Lacomm Co., Ltd. and Gloria Techniques, Korea, as a researcher. In 2003, he was a lecturer with the Chosun university, Gwangju, Korea. Since 2005, he has been an Assistance Professor, Chosun university. His research interests are in application of magneto-optical film, laser and CCD line scan sensor, and development of magnetic camera. He is the author or coauthor of fifteen patents and over 50 scientific papers. Jiseong Hwang was born in Republic of Korea in 1979. He received the B.S and M.S degree in control and instrumentation engineering in 2005 and 2006, respectively, from the Chosun University, Gwangju, korea, where he is currently working toward the Ph.D. degree. His research interests are NDT and Evaluation, Magnetic camera. Jongwoo Jun was born in Korea in 1974. He received the bachelor degree in electronics engineering from Inje University, Kimhae, Korea, in 1999. He received the master degree in electronics engineering from Changwon University, Changwon, Korea, in 2005. Also he is currently working toward the Ph.D. degree in information & communication engineering from Chosun University, Gwangju, Korea. He worked for Lacomm Co., Ltd. and Gloria Techniques from 1999 to 2005, Korea, as a researcher. His research interests are development of magnetic camera, NDT and evaluation. Dr. Seho Choi was born in Korea in 1964. He received bachelor degree in the department of electrical and electronic engineering from Kyungpook National University, Daegu, Korea, in 1987. And he received master degree in the department of elec trical and electronic engineering from Korea Advanced Institute of Science and Technology in 1989. He received Ph.D. degree in the department of electrical and electronic engineering from the University of Sheffield in the U.K. in 2001. He had been worked for Agency for Defense Development as a Researcher from 1989 to 1992, Korea. Since 1993, he has been worked for POSCO Research Lab. as a principal researcher. His main research activities are developing Surface Defect Inspection System for hot and cold rolled steel strip, hot wire rod, and hot slab. He is also interested in developing Internal Defect Detection System for steel products by using Ultra-sonic and magnetic camera techniques. His major is image processing to detect tiny defect in high background noise image. He published many scientific papers as the author or coauthor.     

Experimental and numerical studies on the thermal analysis of the plate in indirectly fired continuous heat treatment furnace

Experimental and numerical studies were performed by considering convective and radiative heat transfer to predict the transient thermal behavior of a plate in an indirectly fired continuous heat treatment furnace. The temperature profiles in the plate were determined by solving the transient one-dimensional heat conduction equation in conjunction with appropriate boundary conditions by using a time marching scheme. The results obtained from the transient analysis were substantiated by comparing with experimental results. Additionally, parametric investigations were performed to examine how the thermal behavior of the plate is affected by plate and refractory emissivities, charging temperature and residence time of the plate, gas temperature of the work and drive sides of the heat treatment furnace, and plate thickness. This paper was recommended for publication in revised form by Associate Editor Ohchae Kwon Young-Deuk Kim is a graduate student at Hanyang University in Seoul, Korea. He earned his B.S. in Mechanical Engineering from Korea Maritime University in 2002 and his M.S. in mechanical engineering from Hanyang university in 2004. His current research areas are modeling of automotive aftertreatment catalysts, optimal design of thermal systems, and phase change modeling with free surface flow. Deok-Hong Kang is a senior researcher at the RIST (Research Institute of Industrial Science and Technology) in Pohang, Korea. He earned his B.S. and M.S. in mechanical engineering from Hanyang University in 1989 and 1993, respectively, and his Ph.D. in mechanical engineering from POSTECH in 2004. His current research areas are mathematical modeling for combustion control, furnace optimization control system, and energy saving engineering in all kinds of furnaces. Woo-Seung Kim is a professor in mechanical engineering at Hanyang University in Ansan, Korea. He earned his B.S. in Mechanical Engineering in 1981 from Hanyang University and his M.S. and Ph.D. in mechanical engineering from North Carolina State University in 1986 and 1989, respectively. His current research areas are modeling of automotive aftertreatment systems, inverse heat transfer problems, optimal design of thermal systems, and phase change heat transfer problems with free surface flow.     

Experimental investigation of nanoparticle formation characteristics from advanced gasoline and diesel fueled light duty vehicles under different certification driving modes

This paper mainly focused on the comparison of nanoparticle size distribution and number concentration level characteristics with gasoline and diesel fueled light duty vehicles. In the engine research, particle size distribution and number concentrations were analyzed by a DMS500 with engine parameters. Time-resolved particle number concentration levels from test vehicles were measured by a golden particle measurement system (GPMS) as recommended by a Particle Measurement Programme (PMP) on certification modes such as New European Driving Cycle (NEDC), Federal Test Procedure (FTP)-75, and Highway Fuel Economy Test (HWFET). In addition, particle emission characteristics from vehicles were analyzed by DMS500 during transient and high-speed driving conditions. From the results, we found that the formation of particles was highly dependent on vehicle speed and load conditions for each mode. The diesel vehicle equipped with a particulate filter showed substantial reduction of the total particle number whose number concentration was equivalent to that of the gasoline vehicle. The nucleation mode particles from gasoline fuel were mainly emitted; however, the accumulation mode particles from the diesel fuel were generally analyzed. This paper was recommended for publication in revised form by Associate Editor Kyoung Doug Min Simsoo Park received his B.S. and M.S. degrees from Seoul National University in 1977 and 1979, respectively, and a Ph.D. from the State University of New York at Stony Brook. He served as a Chief Research Engineer at Hyundai Motor Company, a Director for Publication of the KSME, a Technical Advisor of Hyundai-Kia Motor Company, and an Editing Director, Project Director, International Director, Accounting Director, and General Affair Director of KSAE. He is currently Vice President and Editor-in-Chief of IJAT at KSAE and a professor in school of mechanical engineering at Korea University. Hyungmin Lee received his B.S. degrees from Republic of Korea Naval Academy in 1997 and his M.S. degrees from Korea University in 2005, respectively. He served as an Operation Officer, Command Engineer Officer at various naval vessels. He is currently Ph.D. course in school of mechanical engineering at Korea University and his rank is a Lieutenant Commander of Korea Navy.     

Hydraulic transport of sand-water mixtures in pipelines Part I. Experiment

The hydraulic transport characteristics of sand-water mixtures in circular and square pipelines are experimentally investigated by changing the Reynolds number and volumetric delivered concentration. The hydraulic gradients are increased along with the Reynolds number. When the mean velocity is larger than the critical velocity, the hydraulic gradient of sand-water mixture in the square duct is larger than that in the circular pipe. The deposition-limit velocity in the square duct is smaller than that in the circular pipe. Thus, it can be concluded that the square duct transports sands more effectively than the circular pipe in a low operating range of velocity. The empirical correlation between the hydraulic gradient and the Reynolds number is obtained. It is believed that the present data and empirical equation can be used to validate the numerical methods developed for the analysis of the transport characteristics of slurry in the circular and square pipelines. This paper was recommended for publication in revised form by Associate Editor Jun Sang Park Chang-Hee Kim received a B.S. degree in Mechanical Engineering from Hanyang University in 1985. He then went on to receive his M.S. degrees from Hanyang University in 1994. Mr. Kim has joined Hyundai Engineering and Construction Company after his degree and is currently working for Oil & Gas Plant as a Procurement Manager. Man-Soo Lee received his M.S. and Ph.D. degrees from civil eng. dept. of Seoul National University in 1992 and 2004, respectively. He has joined Hyundai Engineering and Construction company since 1991 as a research engineer. Recently assisting a big dredging & reclamation project of Hyundai near Incheon Airport in Korea, he is responsible for the geotechnical researching team of civil engineering division at Hyundai Institute of Construction Technology. Cheol-Heui Han received a B.S. degree in Mechanical Engineering from Hanyang University in 1993. He received his M.S. and Ph.D. degrees from Hanyang University. in 1998 and 2003, respectively. Then, he worked as a visiting post-doctoral researcher at the Dept. of Aerospace and Ocean Engineering at Virginia Tech, USA. Dr. Han is currently a Assistant Professor at the Department of Aeronautical and Mechanical Design Engineering. Dr. Han’s research interests are in the area of biomimetics, aircraft and turbomachine design.     

Dual stage and an image processing-based method for sight stabilization

This paper presents a combined dual stage-based mechanical and image-based stabilization scheme for a three-axis image-tracking sight system. To improve the stabilization and tracking accuracy, a secondary stage actuated by a pair of electro-magnets is mounted on a conventional elevation gimbal. For the remaining roll axis stabilization, an electronic digital- image stabilization technique is introduced to estimate and correct roll motions. Experimental results are given to demonstrate the effectiveness of the proposed stabilization system and the image-stabilization scheme. This paper was recommended for publication in revised form by Associate Editor Dong Hwan Kim Joon Lyou received a B.S. degree in Electronics Engineering from Seoul National University in 1978. He then went on to receive M.S. and Ph.D. degrees from KAIST in 1980 and 1984, respectively. Dr. Lyou is currently a professor of the Department of Electronics Engineering at Chungnam National University in Daejeon, Korea. His research interests include industrial control and sensor signal processing, IT based robotics, and navigation systems. MinSig Kang received a B.S. degree from the Department of Mechanical Engineering of Seoul National University in 1980. He then went on to receive M.S. and Ph.D. degrees from KAIST in 1983 and 1987, respectively. He worked for the Agency for Defence Development during 1987–1998. Dr. Kang is currently a professor of the Department of Mechanical and Automotive Engineering at Kyungwon University in Sungnam, Korea. His research interests include dynamic systems measurement and control, industrial robotics, and manufacturing systems. HwyKuen Kwak received a B.S. degree in Electronics Engineering from Chungnam National University in 2005. He is currently working on his M.S. and Ph.D. course at Chungnam National University in Daejeon, Korea. His research areas are image signal processing, sensors and digital control systems. YoungJun Choi received a B.S. and M.S. degree in Mechanical Engineering from Kyungwon University in 2004 and 2006. He is currently a researcher for the Agency for Defence Development in Daejeon, Korea. His research fields are dynamic systems measurement and control, satellite systems, navigation systems and smart materials.     

Evaluation of elastic modulus for unidirectionally aligned short fiber composites

An analytical approach of to reinforcement for of short fiber reinforced composites has been extended to include the estimation of elastic modulus. The model is based on the theoretical development of shear lag theory developed by Cox for unidirectionally Aligned aligned Short short Fiber fiber Compositescomposites. Thus, the evolution of conventional models is described in detail along with the effect on the modulus of various parameters. Results are shown with experimental data as well as the comparison of other theories. It is found that the present model agrees well with experimental data and resolves some of the discrepancies among the previous models. It is also found that the present model is very accurate yet relatively simple to predict Young’s modulus of discontinuous composites and has the capability to correctly predict the effects of fiber aspect ratio, fiber volume fraction, and fiber/matrix modulus ratio. This paper was recommended for publication in revised form by Associate Editor Chongdu Cho Hong Gun Kim received a B.S. and M.S. degree in Mechanical Engineering from Hanyang University in 1979 and 1984. He then went on to receive his Ph.D. degrees from University of Massachusetts in 1992, respectively. Dr. Kim is currently a Professor at the Department of Mechanical & Automotive Engineering at Jeonju University in jeonju, Korea. He is currently serving as an Editor of the KSAE and KSMTE. Dr. Kim’s research interests are in the area of fuel cell, FEM analysis, mechanical design, and composite mechanics. Lee Ku Kwac received a B.S. degree in Precision Mechanical Engineering from Chosun University in 1999. He then went on to receive his M.S. and Ph.D. degrees from Chosun University in 2001 and 2005, respectively. Dr. Kwac currently a Professor at the Department of Mechanical & Automotive Engineering at Jeonju University in jeonju, Korea. Dr. Kwac’s research interests are in the area of fuel cell, nano-mechanism, and micro-machining.     

Effects of various intake valve timings and spark timings on combustion,cyclic THC and NOX emissions during cold start phase with idle operation in CVVT engine

In a gasoline SI engine, valve events and spark timings put forth a major influence on overall efficiency, fuel economy, and exhaust emissions. Residual gases controlled by the valve overlap can be used to reduce NOx emissions and the spark retardation technique can be used to improve raw THC emissions and catalyst light-off performance during the cold start phase. This paper investigated the behaviors of the engine and its combustion characteristics with various intake valve timings and spark timings during the fast idle condition and cold start. And cyclic THC and NOx emissions were measured at the exhaust port and their formation mechanisms were examined with fast response gas analyzers. As a result, THCs and NOx were reduced by 35% and 23% with optimizing valve overlap and spark advance during the cold transient start phase. Consequently, the valve events and ignition timings were found to significantly affect combustion phenomena and cold-start emissions. This paper was recommended for publication in revised form by Associate Editor Kyoung Doug Min Simsoo Park received his B.S. and M.S. degrees from Seoul National University in 1977 and 1979, respectively, and a Ph.D. from the State University of New York at Stony Brook. He served as a Principle Research Engineer at Hyundai Motor Company, a Director for Publication of the KSME, a Technical Advisor of Hyundai-Kia Motor Company, and an Editing Director, Project Director, International Director, Accounting Director, and General Affair Director of KSAE. He is currently Vice President of Editing and International at KSAE and a professor of mechanical engineering at Korea University.     

Nanomechanics of biomolecules: focus on DNA

Nano-mechanical measurements and manipulations at the single-cell and single-molecular levels using the atomic force microscope (AFM) and optical tweezers are presenting fascinating opportunities to the researchers in bioscience and biotechnology. Single molecule biophysics technologies, due to their capability to detect transient states of molecules and biomolecular complexes, are the methods of choice for studies in DNA structure and dynamics, DNA-DNA and DNA-protein interactions, and viral DNA packaging. The aim of this review is to describe the recent developments of scientific tools and the knowledge gained in single molecule DNA mechanics such as DNA elasticity, electrostatics, condensation and interactions of DNA with surrounding fluids during its hydrodynamic flow. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.recommended for publication in revised form by Associate Editor In-Ha Sung Y. Eugene Pak is currently serving as the Director of Research Planning Team at the Advanced Institute of Convergence Technology in Seoul National University. He received B.S. degree in Mechanical Engineering from the State University of New York at Buffalo in 1980, and M.S. and Ph.D. degrees in Mechanical Engineering from Stanford University in 1982 and 1985, respectively. After obtaining the Ph.D. degree, he worked as Senior Research Scientist at Northrup-Grumman Corporate Research Center. He joined the Samsung Advanced Institute of Technology (SAIT) in 1995 and has since been leading and expanding research programs in MEMS, Nano and Biotechnology. Sanghyo Kim received B.S. degree in Polymer Science and Engineering from Pusan National University in 1986. He then went on to receive his M.S. and Ph.D. degrees from POSTECH in 1992 and1996, respectively. After the Ph.D. degree, he worked as Senior Researcher at University of Sheffield, UK and University of Cincinnati, USA. He joined the Samsung Electronics Ltd. as a principal researcher in 2002. Dr. Kim is currently an Assistant Professor at the College of Bionano Technology, Kyungwon University in Gyeonggi, Korea. His research interest is in the area of pervasive healthcare information technology including ubiquitous healthcare system and cell/tissue based lab-on-a-chip. Mohana Marimuthu received her Bachelor degree in Pharmacy from The TamilNadu Dr. M.G.R Medical University, India, in 2007. She worked as a clinical study coordinator in phase III clinical trials (Asthma and Chronic Obstructive Pulmonary Disease) at pulmonary department in Sri Ramakrishna Hospital and Institute of Health science, India until February 2008. She is currently doing final year M.S degree in Bionanotechnology at Kyungwon University, Korea. Her research interests extend into microfluidics, tissue engineering and drug delivery.     

Optimization of rapid thermal processing for uniform temperature distribution on wafer surface

An optimization of rapid thermal processing (RTP) was conducted to obtain uniform temperature distribution on a wafer surface by using linear programming and radiative heat transfer modeling. The results show that two heating lamp zones are needed to maintain uniform wafer temperature and the optimal lamp positions are unique for a given geometry and not affected by wafer temperatures. The radii of heating lamps, which were obtained by optimization, are 45 mm and 108 mm. The emissivity and temperature of the chamber wall do not significantly affect the optimal condition. With obtained optimum geometry of the RTP chamber and lamp positions, the wafer surface temperatures were calculated. The uniformity allowance of the wafer surface is less than ±1°C when the mean temperature of the wafer surface is 1000°C. This paper was recommended for publication in revised form by Associate Editor Dongsik Kim Hyuck-Keun Oh received the B.S. and M.S degrees in Mechanical & Aerospace Engineering from Seoul National University in 2000 and 2002, respectively. He had experienced mechanical and electrical engineering in the Samsung SDI Corporation on various display devices between 2002 and 2007. He is now pursuing the Ph.D degree in Mechanical & Aerospace engineering at Seoul National University, Korea. His research interests are heat transfer and thermal management with a focus on power generation and energy efficiency. Sae Byul Kang received the B.S degree in Mechanical engineering from Korea University in 1996. He then went on to receive his M.S and Ph.D. degrees from Seoul National University in 1998 and 2003, respectively. Dr. Kang is currently a senior researcher at the Korea Institute of Energy Research in Daejeon, Korea. Dr. Kang’s research interests are development of industrial boiler and burner for bio-mass. Young Ki Choi received the B.S and M.S degrees in Mechanical engineering from Seoul National University in 1978 and 1980, respectively and the Ph.D. de-gree in mechanical engineering from the University of California at Berkeley in 1986. He is currently a professor at the School of Mechanical Engineering, Chung Ang University, Korea. His research interests are in the area of micro/nanoscale energy conversion and transport, computational fluid dynamics, and molecular dynamics simulations. Joon Sik Lee received the B.S and M.S degrees in Mechanical engineering from Seoul National University in 1976 and 1980, respectively and the Ph.D. degree in mechanical engineering from the University of California at Berkeley in 1985. He is currently a professor at the School of Mechanical & Aerospace Engineering, Seoul National University, Korea. He is also the director of Micro Thermal System Research Center. His research interests are in the area of micro/nanoscale energy conversion and transport, thermal management for power generation and energy efficiency, and various convective heat transport phenomena such as pool boiling and nanofluid.     

A study on the MHD (magnetohydrodynamic) micropump with side-walled electrodes

This paper presents the continuous flow MHD(magnetohydrodynamic) micropump with side walled electrodes using Lorentz force, which is perpendicular to both magnetic and electric fields, for the application of microfluidic systems. A theoretically simplified MHD flow model includes the theory of fluid dynamics and electromagnetics and it is based upon the steady state, incompressible and fully developed laminar flow theory. A numerical analysis with the finite difference method is employed for solving the velocity profile of the working fluid across the microchannel under various operation currents and magnetic flux densities. In addition, the commercial CFD code called CFD-ACE has been utilized for simulating the MHD micropump. When the program was run(CFD-ACE), the applied current and magnetic flux density were set to be the variables that affected the performance of the MHD micropump. The MHD micropump was fabricated by using MEMS technology. The performance of the MHD micropump was obtained by measuring the flow rate as the applied DC current was changed from 0 to 1mA at 4900 and 3300 Gauss for the electrodes with the lengths of 5000, 7500 and 10000 μm, respectively. The experimental results were compared with the analytical and the numerical results. In addition, with the theoretical analysis and the preliminary experiments, we propose a final model for a simple and new MHD micropump, which could be applicable to microfluidic systems. This paper was recommended for publication in revised form by Associate Editor Seungbae Lee Bumkyoo Choi received a B.S. degree in mechanical engineering, M.S. in mechanical design engineering from Seoul National University, Seoul, Korea in 1981 and 1983 respectively, and PhD in engineering mechanics from the University of Wisconsin, Madison in 1992. From 1992 to 1994, he was a technical staff member of CXrL (Center of X-ray Lithography) in the University of Wisconsin where he developed a computer code for thermal modeling of X-ray mask membrane during synchrotron radiation. He is currently a professor in the Dept. of Mechanical Engineering of Sogang Univ., Seoul, Korea. His research interest includes microelec-tromechanical system (MEMS), micromatching and microfabrication technologies, and modeling issues. Sangsoo Lim received a B.S. degree in mechanical engineering from Sogang University, Seoul, Korea in 2005. He currently works at Hyundai Motors.     

Optimum design of the cored linear motor using experiment design

Recently, a linear motor has been becoming widely popular in office automation (OA) and factory automation (FA) systems due to its simple structure, high-speed operation, and precise positioning. In this study, a cored linear motor was designed to have a large thrust and small ripple because these are considered as indicators of motor performance. The thrust and ripple of the linear motor can be calculated by a finite element method (FEM) commercial program such as ANSYS. To design the cored linear motor, first, the design variables were selected through ANOM and ANOVA. The response surface method was applied to formulate the cost function of the second-order regression model, which can evaluate motor performance. By optimizing the cost function, it was possible to realize quickly the optimum design for a cored linear motor. As a result, the performance of the motor was improved. This paper was recommended for publication in revised form by Associate Editor Tae Hee Lee Mr. Sungill Seo received his B.S. and M.S. degree from the department of Mechanical Engineering, Sogang University, Seoul, S. Korea in 2006 and 2009, respectively. Mr. Seo is currently working for Hyundai Engineering. His research interests are in the area of optimum design of electric motors, metal forming, and process design. Naksoo Kim received his B.S. and M.S. degree from the department of Mechanical Design, Seoul National Uni-versity in 1982 and 1984, respectively. He then went on to receive his Ph. D. degree from U.C. Berkeley. Dr. Kim had worked for the ERC/NSM at the Ohio State University as a senior researcher and Hongik University as an assistant professor. He is currently a professor at the department of mechanical engineering, Sogang University. Dr. Kim’s research interests are in the area of metal forming plasticity, computer aided process analysis, and optimal design.     

Numerical simulation of displacement instabilities of surface grooves on an alumina forming alloy during thermal cycling oxidation

Displacement instability of the thermally grown oxide (TGO) is a fundamental source of failure in thermal barrier systems. In this work, a finite element analysis has been performed to analyze the displacement instability occurring at a heat resistant metal with superficial TGO subjected to thermal cycling. Lateral and in-plane growth of the TGO which happens during high temperature is simulated by means of material property change from the substrate metal to the TGO. Most of the material properties including the TGO growth are based on the results experimentally obtained in-house. Results of the finite element analyses agree well with the experimental observation, which proves the accuracy and validity of this simulation. The technique will be useful for future work on more complicated phenomena such as deformation under thermo-mechanical cycling. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho Jun Ding received his B.S. degree in Mechanical Engineering from Chongqing Institute of Technology, China, in 2000. He then received his M.S. degree from Chongqing University, China, in 2004. Currently a Ph. D candidate at the Graduate School of Mechanical Systems Engineering at Chonnam National University in Gwangju, Korea, he is mainly working on the theoretical and numerical analyses of mechanical behaviors of various materials. Feng-Xun Li received his B.S. degree from the Department of Mechanical Engineering of Yanbian University, China, in 2005. He then received his M.S. degree from Chonnam National University, Korea, in 2007. He is currently a Ph. D candidate at the Graduate School of Mechanical Systems Engineering at Chonnam National University in Gwangju, Korea and is mainly working on the deformation mechanism of thermally grown oxide. Ki-Ju Kang received his B.S. degree in Mechanical Engineering from Chonnam National University, Korea, in 1981. He then received his M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology in 1983 and 1988, respectively. Dr. Kang is currently a Professor at the School of Mechanical Systems Engineering at Chonnam National University in Gwangju, Korea. His laboratory is designated as a national research laboratory. His research interests include the optimal designs and manufacturing technologies of various types of porous cellular metal and mechanical behaviors of a thermally grown oxide at high temperature.     

Approximate velocity scale for primary and secondary dual-inlet side-dump flows

Effects of the bulk inlet velocity on the characteristics of dual-inlet side-dump flows are numerically investigated. Non-reacting subsonic turbulent flow is solved by a preconditioned Reynolds-averaged Navier-Stokes equation system with low-Reynolds number k − ɛ turbulence model. The numerical method is properly validated with measured velocity distributions in the head dome and the combustor. With substantial increase in the bulk inlet velocity, general profiles of essential primary and secondary flows normalized by the bulk inlet velocity are quantitatively invariant to the changes in the bulk inlet velocity. This paper was recommended for publication in revised form by Associate Editor Do Hyung Lee Seung-chai Jung received his B.S. degree in Mechanical Engineering from Yonsei University, Korea, in 2001. He then received his M.S. degree in Mechanical Engineering from Yonsei University, Korea, in 2005. Mr. Jung is currently a Ph. D. candidate at Yonsei University, where he is majoring in Mechanical Engineering. Mr. Jung’s research interests include propulsion system and particle-surface collision dynamics. Byung-Hoon Park received his B.S. degree in Mechanical Design and Production Engineering from Yonsei University in 2003. He is currently a Ph.D. candidate in Yonsei University in Seoul, Korea. His research interests include performance design of propulsion systems and nu-merical analysis of instability in multiphase turbulent reacting flow-fields. Hyun Ko received his B.S. degree in Aerospace Engineering from Chonbuk National University, Korea, in 1996. He then received his M.S. degree in Mechanical Design from Chonbuk National University, Korea, in 1998. In 2005, he obtained his Ph.D. degree from Yonsei University, where he majored in mechanical engineering. Dr. Ko is currently a Principal Research Engineer of the MicroFriend Co., Ltd. in Seoul, Korea. His research interests include propulsion related systems and computational fluid dynamics. Woong-sup Yoon received his B.S. degree in Mechanical Engineering from Yonsei University, Korea, in 1985. He then received his M.S. degree from University of Missouri-Rolla in 1989. In 1992, he obtained his Ph.D. degree from the University of Alabama in Huntsville, where he majored in mechanical and aerospace engineering. Dr. Yoon is currently a professor at the School of Mechanical Engineering at Yonsei University in Seoul, Korea. His research interests include propulsion system and particle-related environmental/ thermal engineering.     

Collision-free motion coordination of heterogeneous robots

This paper proposes a method to coordinate the motion of multiple heterogeneous robots on a network. The proposed method uses prioritization and avoidance. Priority is assigned to each robot; a robot with lower priority avoids the robots of higher priority. To avoid collision with other robots, elastic force and potential field force are used. Also, the method can be applied separately to the motion planning of a part of a robot from that of the other parts of the robot. This is useful for application to the robots of the type mobile manipulator or highly redundant robots. The method is tested by simulation, and it results in smooth and adaptive coordination in an environment with multiple heterogeneous robots. This paper was recommended for publication in revised form by Associate Editor Jong Hyeon Park Nak Yong Ko received the B.S. degree, M.S. degree, and Ph.D. degree from the Department of Control and Instrumentation Engineering, Seoul National University, Korea, in the field of robotics. He is Professor of the department of Control, Instru-mentation, and Robot Engineering, Chosun University, Korea, from 1992. During 1996–1997 and 2004–2005, he worked as a visiting research scientist at the Robotics Institute of Carnegie Mellon University. His research interests include autonomous motion of mobile robots(collision avoidance, localization, map building, navigation, and planning), manipulator force/torque control, and incorporation of mobile robot technology into GIS. Dong Jin Seo is a Research Engineer in Robotics Institute at REDONE Tech. He earned B.A degree, M.S. degree and Ph.D. degree from the Department of Control and Instrumentation Engineering, Chosun Uni-versity, Korea in 2000, 2002 and 2006. During 2004–2005, he worked as a visiting student scholar at the Robotics Institute of Carnegie Mellon University, USA. His research interests are multi-robot cooperation, localization, navigation and modeling robot simulation systems with uncertainty. Reid Gordon Simmons is a research scientist in the department of com-puter science and robotics institute at Carnegie Mellon University, USA. He earned his B.A degree in 1979 in computer science from SUNY at Buffalo, and his M.S and Ph.D. degrees from MIT in 1983 and 1988, respectively, in the field of artificial intelligence. His research interests focus on developing reliable, highly autonomous systems(especially mobile robots) that operate in rich, uncertain environments. In particular, he is interested in architectures for autonomy the combine deliberative and reactive behavior, reliable execution monitoring and error recovery, multi-robot coordination, probabilistic and symbolic planning, formal verification of autonomous systems, and human-robot social interaction.     

Theoretical analysis and experiments of axial flux pm motors with minimized cogging torque

This paper deals with analysis and experiments of an axial flux PM (AFPM) brushless dc motor with minimized cogging torque. Recently, many optimal designs for the AFPM motor have been done by finite element (FE) analysis, but such analysis is time-consuming. In this study, the equation of magnetic flux lines existing between PMs and core is assumed mathematically and the minimum cogging torque is calculated theoretically and geometrically without FE analysis. The form of equation is assumed to be a 2^nd order polynomial. The skew angle that makes the cogging torque minimized is calculated theoretically, and the value of minimum cogging torque is compared with the results obtained by FE analysis and experiments. The maximum cogging torque of a proposed AFPM motor has the smallest value approximately at a skew angle of 4° in both the theoretical and FE analysis. Compared with the non-skewed motor, the cogging torque of the skewed motor can be decreased to over 90%, which has a value of 5% of the rated torque. Two types of stator cores, with the skew angle of 0° and 4°, are analyzed, manufactured, and tested experimentally. This paper was recommended for publication in revised form by Associate Editor Hong Hee Yoo Dong Ho Kim received B.S. and M.S. degrees in Mechanical Engineering from Pusan National University in 1982 and 1984, respectively. He then received his Ph.D. degree from Yonsei University in 2007. Dr. Kim is currently a Professor at the Department of Automation and Robots at Kyonggi Institute of Technology in Gyeonggi, Korea. His research interests are in the area of production automation. Jong Hyun Choi received B.S., M.S., and Ph.D. degrees in Mechanical Engineering from Yonsei University, Seoul, Korea, in 1996, 1998, and 2006, respectively. Dr. Choi is currently a post-doctor at the School of Mechanical Engineering at Yonsei University. His research interests are in the area of electromagnetic actuators and magnetic levitation system. Chang Woo Son received a B.S. from Kyungwon University, Seoul, Korea, in 2006, and his M.S. degree from Yonsei University in 2008, all in mechanical engi-neering. He is currently a research engineer at DA Laboratory of LG Electronics in Seoul, Korea. His research interests are in the area of electromagnetic actuators. Yoon Su Baek received B.S. and M.S. degrees from Yonsei University, Seoul, Korea, in 1979 and 1981, respectively, and M.S. and Ph.D. degrees from Oregon State University in 1986 and 1990, respectively, all in mechanical engineering. He worked for Samsung Heavy Industry Ltd. as head research engineer at Mechatronics Research Center from 1990 to 1993. Dr. Baek is currently a Professor at the School of Mechanical Engineering at Yonsei University. His research interests are motion devices and robotics, especially relating to multi-D.O.F. actuators. He is also interested in magnetic brake and levitation system.     

Inter-laboratory correlation exercise on a light-duty diesel passenger vehicle to verify nano-particle emission characteristics by Korea particle measurement program

The Light Duty Inter-Laboratory Correlation Exercise (ILCE) final report, performed with the ‘PMP Golden Vehicle’ at nine laboratories in the EU, Korea and Japan to demonstrate repeatability and reproducibility of the particle number concentration emissions measurement techniques proposed by the Particle Measurement Program (PMP), was released in 2007. The ILCE was conducted by the Korea Particle Measurement Program (KPMP) with a domestic diesel passenger vehicle equipped with a diesel particulate filter (DPF) between three certification laboratories and the research center of an automotive manufacturer to meet future regulations (EURO 5 and EURO 6) of particle number concentration for light-duty vehicles in early 2008. This research focused on measuring the particulate matter emission (particle number and mass) levels of a representative light-duty diesel passenger vehicle during new European driving cycle (NEDC) mode to analyze the repeatability and reproducibility between laboratories in Korea. From the ILCE test results in Korea, the mean total particle number concentration levels ranged from 5.43E+10 #/km to 1.58E+11 #/km and 0.0003 g/km to 0.0036 g/km for particle mass. Repeatability between participating laboratories ranged from 32% to 66% for particle number, 11% to 70% for particle mass; the reproducibility level was 46% for particle number, and 66% for particle mass emission. This paper was recommended for publication in revised form by Associate Editor Kyoung Doug Min Simsoo Park received his B.S. and M.S. degrees from Seoul National University in 1997 and 1979, respectively, and a Ph.D. from the State University of New York at Stony Brook. He served as a Chief Research Engineer at Hyundai Motor Company, a Director for Publication of the KSME, a Technical Advisor of Hyundai-Kia Motor Company, and an Editing Director, Project Director, International Director, Accounting Director, and General Affair Director of KSAE. He is currently Vice President and of Editor-in-Chief of IJAT at KSAE and a professor in school of mechanical engineering at Korea University.     

Investigation of emission characteristics affected by new cooling system in a diesel engine

In a typical cooling system of automotive engine, a mechanical water pump is used to control the flow rate of coolant. However, this traditional cooling system is not suitable for a high efficiency performance in terms of fuel economy and exhaust emission. Therefore, it is necessary to develop a new technology for engine cooling systems. These days, the electronic water pump is spotlighted as the new cooling system of an engine. The new cooling system can provide more flexible control of the coolant flow rate and the engine temperature, which used to be strongly relied on the engine driving conditions such as load and speed. In this study, an engine experiment was carried out on a New European Drive Cycle (NEDC) with a 2.7L diesel engine. The electric water pump operated by BLDC motor and the electronic valve were installed in the cooling system to control the coolant flow rate and temperature. This paper explains that the exhaust emissions were reduced with an increase in the engine temperature and a decrease in the coolant flow. From this experiment, we found that increasing coolant temperature had a significant effect on reducing the emissions (e.g. THC and CO). Decreasing coolant flow also affected the reduction of emissions. In contrast, NOx emission was observed to increase in these conditions. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Kyung-Wook Choi received his B.S. degree in Mechanical Engineering from Hanyang University, Korea, in 2006. He is now working on a doctoral degree in Hanyang University. Kyung-Wook’s research interests include Hybrid Electric Vehicle, Internal Engine Combustion, and Engine Cooling System. Ki-bum Kim was awarded a bachelor’s degree in naval architecture and ocean engineering from Chung-Nam National University in the Republic of Korea. In August 2001, he began graduate study at the University of Florida. Kibum graduated with a Master of Science degree in mechanical engineering from the University of Florida in August 2003. He went on to earn his Ph.D. in mechanical engineering, also at the University of Florida, in August 2006. He is working as a research professor at Hanyang University. Ki-Hyung Lee is a Professor at the department of mechanical engineering in Hanyang University. He received his B.S and M.S degree in Hanyang University in 1983 and 1986. Then he graduated with a Ph.D. degree in mechanical Engineering at Kobe University, Japan in 1989. He worked as a research engineer at Nissan motor’s central technical center for 4 years.     

Effect of imperfections on the mechanical behavior of wire-woven bulk kagome truss PCMs under shear loading

Wire-woven bulk kagome (WBK) materials are a new class of cellular metallic structures possessing desired mechanical performance and can be fabricated easily by assembling metallic wires. In previous studies, the WBK materials were shown to have high strength and weak sensitivity on imperfections under compressive loads. In this paper, we present numerical simulation results on the mechanical performance of WBK and its sensitivity on imperfections under shear loads. Two types of statistical imperfections on geometry and material property were introduced in the simulation models as likewise the previous studies. The simulation results were compared with the experimental measurement on the WBK made of stainless wire (SUS304). The WBK were shown to have a good isotropic mechanical strength under various orientations of shear loadings. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho Sangil Hyun received his B.S. and M.S. degrees in physics from Seoul National University, Korea, in 1986 and 1989. He received his Ph.D. degree in solid state theory from Michigan State Uni-versity in 1998. Dr. Hyun is currently a senior researcher at the simulation center in Korea Inst. of Ceramic Eng. & Tech. (KICET). He is mainly working on computational studies on multifunctional cha-racteristics of fine ceramics, metals, and composites. He also develops a multiscale modeling on nanotribology and nanofluidics. Ji-Eun Choi received her B.S. and M.S degrees in Mechanical Engineering from Chosun University, Korea, in 1999 and 2001. Ms. Choi is currently an associate research engineer at the automobile research center in Chonnam National University. She is mainly working on the theoretical and numerical analyses on truss PCMs (Periodic Cellular Metals). Ki-Ju Kang received his B.S. degree in Mechanical Engineering from Chonnam National University, Korea, in 1981. He then received his M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology in 1983 and 1988, respectively. Dr. Kang is currently a Professor at the School of Mechanical Systems Engineering at Chonnam National University in Gwangju, Korea. Prof. Kang’s lab is designated as a national research Lab. His research interests include the optimal designs and manufacturing technologies of various types of porous cellular metals and mechanical behaviors of a thermally grown oxide at high temperature.     

Data format and browser of lightweight CAD files for dimensional verification over the internet

The demand for the use of 3D CAD data over the Internet environment has been increasing. However, CAD data size has deteriorated the communication effectiveness of 3D CAD files. Good design methodology of a lightweight CAD file is required for rapid transmission on the distributed network environment. In this paper, a file translation system is constructed to produce lightweight CAD files from commercial CAD systems by using InterOp and APIs of the ACIS kernel. Using B-rep models and mesh data extracted from the CAD native files, the lightweight CAD files with topological information are constructed as binary files. As the lightweight CAD files retain topological and geometric information, they are applicable to dimensional verification, digital mock-ups, and visualization of CAD files through a CAD viewer. The effectiveness of the proposed lightweight CAD files is confirmed through various case studies on the CAD viewer. This paper was recommended for publication in revised form by Associate Editor Jooho Choi In-Ho Song received B.S. and M.S. degrees in mechanical engi-neering from Kunsan National University, and Ph.D. degree in mechanical engineering from Hanyang University, Seoul, Korea in 2007. From 2002 to 2007, he served as a team manager to develop CAD and PLM systems in CIES in Korea. He is currently a post-doc researcher in the mechanical engineering department in Hanyang University. As he had developed a lightweight CAD viewing kernel for CAD/CAM systems, he received a New Technology Certificate from Korean Government (MOCIE) in 2005. He also received several prizes from the Korean Society of CAD/CAM Engineers in 2003 and 2004. He specializes in geometric modeling, CAD kernels, product design and digital manufacturing systems. Sung-Chong Chung received the B.S. degree with honors in mechanical engineering from Hanyang University, Seoul, Korea, and the M.S. and Ph. D. in mechanical engineering from KAIST, Seoul, Korea in 1979, 1981 and 1987, respectively. Since 1983, he has been a professor in the School of Mechanical Engineering, Hanyang University, Seoul, Korea. In 2000, he received the outstanding paper award from the North American Manufacturing Research Institution of the Society of Manufacturing Engineers. He received the academic research and software development awards from the Korean Society of Mechanical Engineers and the Korean Society of CAD/CAM Engineers in 2003 and 2004, respectively. His research interests include CAD/CAM, control, mechatronics, manufacturing and precision engineering.