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排序方式: 共有716条查询结果,搜索用时 31 毫秒
51.
Seong-Gu Hong Thak-Sang Byun Richard A. Lowden Lance L. Snead Yutai Katoh 《Journal of the American Ceramic Society》2007,90(1):184-191
A program to develop new methods to measure the fracture strength of the chemical vapor deposition SiC coatings in nuclear fuel particles has been carried out. Internal pressurization and crush test techniques were developed and applied to prototype-sized tubular and hemispherical shell specimens. The fracture strength measured from each test method applying the Weibull two-parameter distribution, and Weibull parameters were measured. It was shown that data generated with each test technique were independent of the test technique applied. This implies that the developed test methods are reliable and provide reasonable strength data. For the same material, fracture strength varied with the specimen geometry and loading configuration. These size and loading configuration effects on the fracture strength are explained with the concept of effective surface. 相似文献
52.
Sang-Eon Kim Soon-Do Yoon Ki-Pung Yoo Hun-Soo Byun 《Korean Journal of Chemical Engineering》2009,26(1):199-205
Experimental cloud-point data of binary and ternary mixtures for poly(isodecyl methacrylate) [P(IDMA)] in supercritical carbon
dioxide, dimethyl ether (DME), propane, propylene, butane and 1-butene have been studied experimentally using a high pressure
variable volume view cell. These systems show the phase behavior at temperature of 308 K to 473 K and pressure up to 255 MPa.
The cloud-point curves for the P(IDMA)+CO2+isodecyl methacrylate (IDMA) are measured in changes of the pressure-temperature (P-T) slope, and with cosolvent concentrations
of 0-60.1 wt%. Also, experimental data of phase behaviors for IDMA in supercritical carbon dioxide is obtained at temperature
range of 313.2–393.2 K and pressure range of 5.8–22.03 MPa. The experimental results were modeled with the Peng-Robinson equation
of state. The location of the P(IDMA)+CO2 cloud-point curve shifts to lower temperatures and pressures when DME is added to P(IDMA)+CO2 solution. The P(IDMA)+C4 hydrocarbons cloud-point curves are ca. 16.0 MPa lower pressures than the P(IDMA)+C3 hydrocarbons curves at constant temperature.
This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological
Engineering of Korea University. 相似文献
53.
Jae-Chul Lee Ji-Young Byun Chang-Seok Oh Hyun-Kwang Seok Ho-In Lee 《Acta Materialia》1997,45(12):5303-5315
SiCp/2024 Al composites were prepared using various processing techniques, such as spray forming, powder metallurgical hot pressing, thixoforming, and compocasting. The interfacial characterizations of these composites were performed using scanning electron microscopy, Auger electron spectrometry, transmission electron microscopy, and X-ray diffraction on reaction products extracted using the electrochemical dissolution. The value of these combined techniques in elucidating the morphologies of the interfacial reaction products was also demonstrated. The influence that each fabrication process has on the extent of the interfacial reaction was studied. Adequate process parameters to fabricate SiCp/Al alloy composites were proposed based on thermodynamic considerations. 相似文献
54.
In hierarchical reliable multicast schemes, the number of repair proxies and their locations influence inter-destination synchronization.
The inter-destination synchronization in multicast environments means the adjustment of the output timing among destinations
over the Internet. Improving the inter-destination synchronization is beneficial to collaborative applications such as multi-conference
system and multi-playing online game. In this paper, we propose a scheme to find the optimal locations of repair proxies that
can improve inter-destination synchronization maximally in heterogeneous network environments. The simulation results show
that if repair proxies are placed by the proposed scheme, delivery delay fairness of inter-destination can be improved by
0.05 maximally. In addition, we perform t-Test on the simulation results in order to verify that our optimal placement improves synchronization. 相似文献
55.
Budiono Doyoung Byun Vu dat Nyugen Jihoon Kim Han Seo Ko 《Journal of Mechanical Science and Technology》2008,22(12):2554-2562
We propose a novel micro/nano-scale nozzle structure, featuring an interfacial line between the hydrophilic and the hydrophobic
surfaces for a jetting system, such as an inkjet head or electrospray devices. This research will investigate the impact of
the interfacial line on flow instability and momentum augmentation as the liquid meniscus moves across the line. The research
methods used in this paper, in respect to micro-and nano-scale channels, are computational fluid dynamics (CFD) and non-equilibrium
molecular dynamics (MD), respectively. With the growing interest in micro/nano electromechanical systems (MEMS/NEMS), many
studies have been conducted to develop an advanced micro/nanofluidic system. However, until now, there have been few in-depth
studies on passive flow control in micro and nano nozzles using the hydrophilic and hydrophobic surface characteristics. In
this research, the sequential arrangement of hydrophilic and hydrophobic surfaces in the nozzle is presented along with an
investigation into how flow instability and momentum augmentation are going to be applied to an efficient micro/nano jetting
system. When a liquid meniscus arrives at the interfacial line between hydrophilic and hydrophobic surfaces, the meniscus
shape changes from concave to convex and the fluid motion near the wall stops until the concave shape is fully converted.
Because the momentum should be conserved, the lost momentum near the wall transfers to the center region, and therefore the
liquid at the center region is accelerated as it crosses the line. If we use this nozzle structure and the augmentation of
the momentum near the center, a tiny droplet can be easily generated.
This paper was recommended for publication in revised form by Associate Editor Haecheon Choi
Doyoung Byun received the B.S., M.S, and Ph.D. degrees in school of mechanical and aerospace engineering from the Korea Advanced Institute
of Science and Technology (KAIST), Taejon, Korea, in 1994, 1996, and 2000, respectively. From 2000 to 2002, he was in the
Korea Institute of Science and Technology Evaluation and Planning as a Senior Researcher. In 2003, he joined the faculty of
the School of Mechanical and Aerospace Engineering, Konkuk University, Seoul, Korea. His current research topics are development
of electrohydrodynamic inkjet head, microfluidic devices, and biomimetic robot systems. His research interests include microfluidics,
MEMS, and biomimetics. 相似文献
56.
Ho-Lim Choi Hee-Jung Byun Won-Gyu Song Jun-Won Son Jong-Tae Lim 《Artificial Life and Robotics》2000,4(4):193-197
We present a method to calssify electromyogram (EMG) signals which are utilized as control signals for a patient-responsive
walker-supported system for paraplegics. Patterns of EMG signals for different walking motions are classified via adequate
filtering, real EMG signal extraction, AR-modeling, and a modified self-organizing feature map (MSOFM). In particular, a data-reducing
extraction algorithm is employed for real EMG signals. Moreover, MSOFM classifies and determines the results automatically
using a fixed map. Finally, the experimental results are presented for validation. 相似文献
57.
Junggeun Jhin Jong Hyeob Baek Dongjin Byun 《Journal of the Society for Information Display》2008,16(4):535-539
Abstract— The structural, electrical, and optical properties of GaN epilayers grown on various ion‐implanted sapphire(0001) substrates by MOCVD were investigated. GaN or AlN buffer layers and pre‐treatment were indispensably introduced before GaN‐epilayer growth. The ion‐implanted substrate's surface had decreased internal free energies during the growth of the ion‐implanted sapphire(0001) substrates. The crystal and optical properties of the GaN epilayers grown in ion‐implanted sapphire(0001) substrates were improved. Also, an excessively roughened and modified surface caused by ions degraded the GaN epilayers. Not only the ionic radius but also the chemical species of implanted sapphire(0001) substrates improved the properties of the GaN epilayers grown by MOCVD. It is obvious that the ion‐implanted pre‐treatment of sapphire(0001) substrates can be an alternative pre‐treatment procedure for GaN deposition and has the potential to improve the properties of the GaN epilayers on sapphire(0001) substrates. 相似文献
58.
In this paper, interface circuits that are suitable for point‐to‐point interconnection with an over 1 Gbps data rate per pin are proposed. To achieve a successful data transfer rate of multi‐gigabits per‐second between two chips with a point‐to‐point interconnection, the input receiver uses an on‐chip parallel terminator of the pass gate style, while the output driver uses the pullup and pulldown transistors of the diode‐connected style. In addition, the novel dynamic voltage level converter (DVLC) has solved such problems as the access time increase and valid data window reduction. These schemes were adopted on a 64 Mb DDR SRAM with a 1.5 Gbps data rate per pin and fabricated using a 0.10 µm dual gate oxide CMOS technology. 相似文献
59.
Seung Wook Yoon Jun Ki Hong Hwa Jung Kim Kwang Yoo Byun 《Electronics Packaging Manufacturing, IEEE Transactions on》2005,28(2):168-175
To evaluate various Pb-free solder systems for leaded package, thin small outline packages (TSOPs) and chip scale packages (CSPs) including leadframe CSP (LFCSP), fine pitch BGA (FBGA), and wafer level CSP (WLCSP) were characterized in terms of board level and mechanical solder joint reliability. For board level solder joint reliability test of TSOPs, daisy chain samples having pure-Sn were prepared and placed on daisy chain printed circuit board (PCB) with Pb-free solder pastes. For CSPs, the same composition of Pb-free solder balls and solder pastes were used for assembly of daisy chain PCB. The samples were subjected to temperature cycle (T/C) tests (-65/spl deg/C/spl sim/150/spl deg/C, -55/spl deg/C/spl sim/125/spl deg/C, 2 cycles/h). Solder joint lifetime was electrically monitored by resistance measurement and the metallurgical characteristics of solder joint were analyzed by microstructural observation on a cross-section sample. In addition, mechanical tests including shock test, variable frequency vibration test, and four point twisting test were carried out with daisy chain packages too. In order to compare the effect of Pb-free solders with those of Sn-Pb solder, Sn-Pb solder balls and solder paste were included. According to this paper, most Pb-free solder systems were compatible with the conventional Sn-Pb solder with respect to board level and mechanical solder joint reliability. For application of Pb-free solder to WLCSP, Cu diffusion barrier layer is required to block the excessive Cu diffusion, which induced Cu trace failure. 相似文献
60.
Woo‐Jin Byun Bong‐Su Kim Kwang Seon Kim Ki‐Chan Eun Myung‐Sun Song Reinhard Kulke Olaf Kersten Gregor Möllenbeck Matthias Rittweger 《ETRI Journal》2010,32(2):195-203
A new vertical transition between a substrate integrated waveguide in a low‐temperature co‐fired ceramic substrate and an air‐filled standard waveguide is proposed in this paper. A rectangular cavity resonator with closely spaced metallic vias is designed to connect the substrate integrated waveguide to the standard air‐filled waveguide. Physical characteristics of an air‐filled WR‐22 to WR‐22 transition are compared with those of the proposed transition. Simulation and experiment demonstrate that the proposed transition shows a ?1.3 dB insertion loss and 6.2 GHz bandwidth with a 10 dB return loss for the back‐to‐back module. A 40 GHz low‐temperature co‐fired ceramic module with the proposed vertical transition is also implemented. The implemented module is very compact, measuring 57 mm × 28 mm × 3.3 mm. 相似文献