A dynamic general equilibrium analysis on fostering a hydrogen economy in Korea

Hydrogen is anticipated to become one of the major alternative energy technologies for a sustainable energy system. This study analyzes the dynamic economic impacts of building a hydrogen economy in Korea employing a dynamic Computable General Equilibrium (CGE) model. As a frontier technology, hydrogen is featured as having a slow diffusion rate due to option value, positive externality, resistance of old technology, and complementary vintages. Without government intervention, hydrogen-derived energy will supply up to 6.5% of final energy demand by 2040. Simulation outcomes show that as price subsidy rates increase by 10%, 20%, and 30%, hydrogen demand will increase by 9.2%, 15.2%, and 37.7%, respectively, of final energy demand by 2040. The output of the transportation sector will increase significantly, while demands for oil and electricity will decline. Demands for coal and LNG will experience little change. Household consumption will decline because of the increase of income taxes. Overall GDP will increase because of the increase in exports and investments. CO₂ emission will decline for medium and high subsidy rate cases, but increase for low subsidy cases. Ultimately, subsidy policy on hydrogen will not be an effective measure for mitigating CO₂ emission in Korea when considering dynamic general equilibrium effects.     

Bonding features and associated mechanisms in kinetic sprayed titanium coatings

This study aims to explore the bonding features and mechanisms present in kinetic spray coatings of commercially pure titanium (CP-Ti) by linking experimental observations with finite element modeling for the purpose of optimizing the deposition process. The numerically predicted deformation features and interface thermomechanical responses of the particles adequately elucidate the deposition characteristics for different impact conditions. The formation of a porous coating by local bonding at relatively low velocity and of a very dense coating accompanied by interfacial melting at higher velocity resulted from deformation localization at high strain rates due to the relatively higher adiabacity as compared with other materials, which is one of the unique bonding mechanisms in CP-Ti. The enhanced thermal boost-up zone due to thermally accelerated adiabatic shear instability by powder preheating resulted in improved coating properties, and is essential for the optimization of economical coating processes.     

Multi-agent based traffic simulation and integrated control of freeway corridors: Part 1 simulation and control model

Freeway corridors consist of urban freeways and parallel arterials for alternative use. Ramp metering in freeways and signal control in arterials are contemporary traffic control methods that have been developed and applied in order to improve the traffic conditions of freeway corridors. However, most existing studies have focused on either optimal ramp metering in freeways or progressive signal strategies between arterial intersections. For efficient control of freeway corridors, ramp metering and signal control must be considered simultaneously, as otherwise the control strategies for freeway operation may disturb arterial traffic. On the other hand, traffic congestion and arterial bottlenecks that arise with increasing traffic volume at peak hours and ineffective signal operation may cause problems with accessibility to freeway ramps and degrade the urban freeway’s ability to act as a through-traffic process. This research dynamically estimates the traffic stream between an urban freeway and its ramps according to changes in the freeway structure, traffic passing demand, and control methods due to restricted valid information. The results are then compared with those from other methods. Finally, the integrated control in the urban freeway traffic axis is optimized based on the expected traffic stream, by using design of experiment (DOE), neural network (NN), and a simulated annealing algorithm. This paper was recommended for publication in revised form by Associate Editor Kyongsu Yi Myung-Won Suh is a professor of Mechanical Engineering. During 1986–1988, he worked in Ford motor company as researcher. During 1989–1995, he worked in technical center of KIA motors. He took a BS Degree in Mechanical Engineering from Seoul National University and an MS Degree in Mechanical Engineering from KAIST, South Korea. He obtained his Doctorate at University of Michigan, USA, in 1989. His research areas include the structure and system optimization, advanced safety vehicle and reliability analysis & optimization. Chul-Ho Bae is a PhD candidate at Sungkyunkwan University in Suwon, South Korea. He accomplished fellowship work as researcher at Mississippi State University, USA, in 2003 and 2005. He worked in Institute of Advanced Machinery and Technology (IMAT) as a Research Assistant in 2004. He was a part time Lecturer in computer aided Mechanical Engineering of Ansan College of Technology, Suwon Science College, and Osan College during 2004–2005. He took a BS Degree in Mechanical Design and an MS Degree in Mechanical Engineering from the Sungkyunkwan University. His research interests include computer aided engineering, reliability engineering, and optimization.     

Codes based on BCK-algebras

The notion of a BCK-valued function on a set is introduced, and related properties are investigated. Codes generated by BCK-valued functions are established.     

pH-sensitive photocatalytic activities of TiO2/poly(vinyl alcohol)/poly(acrylic acid) composite hydrogels

The pH-sensitive photocatalytic system was prepared by embedding TiO₂ into poly(vinyl alcohol)/poly(acrylic acid) hydrogel. Two different type TiO₂/hydrogel composites, such as matrix and nanofiber, were prepared to investigate the morphological effects on the photocatalytic activity. TiO₂ was distributed uniformly in the composite hydrogel and kept the original anatase structure without any structural change. The photocatalytic activity of TiO₂ was evaluated based on the efficiency of photobleaching of dye. The photobleaching of dye was improved greatly as the pH was changed into basic condition and the larger surface area of hydrogel was available for TiO₂ by using nanofiber supports.     

Analytical and experimental studies on optimal details of orthotropic steel decks for long span bridges

Orthotropic steel decks gradually come into general use in long span bridges due to various advantages such as dead weight reduction, easy quality control, and so on. On the other hand, stress concentration is often observed near the connection details, which may lead to fatigue problems and govern the design of the structure. Therefore, researches to understand the structural behaviors and examine stress distribution of details in orthotropic steel decks are required in order to develop an optimal connection detail. In this paper, optimal parameters regarding height, thickness and shear area of a cross-beam and efficiency and shapes of bulkhead plates are characterized by analytical studies and verified by experiments, so that fatigue cracks could be prevented.     

Influence of the interface temperature and strain gradients on the impact energy model of a soft particle on a hard substrate during kinetic spraying

In this study, the individual particle impact behaviors of a soft particle on a hard substrate during a kinetic spraying operation were observed. The ratio of the bonds was compared to the difference between the adhesion and rebound energies. To improve the existing model, the equation for the effective yield stress was modified and a finite element analysis was applied to estimate the temperature and strain gradients. The energy difference was derived from the strain and temperature of the elements and compared to the experimental ratio of the bonds.     

Structure-property relationships of hydroxy-terminated polyether based polyurethane network

In the present work, the effect of crosslink density on HTPE networks has been studied in swelling, thermal and mechanical properties. The solubility parameters of HTPE PUs were obtained by swelling test. They depended on the molar ratio of N-100 and IPDI and equivalent ratio. It was decreased as the content of N-100 was lowered. The thermal characteristics of the network polymer were examined by DSC results. Thermal behavior of HTPE PU network depended on by dangling chain and chain folding in the series using N-100, with NCO/OH ratio as 1.0, 0.8, 0.6. However, when we performed experiment with IPDI and N-100, with NCO/OH ratio as 1.0, the thermal properties depended on M_c. Moreover, using IPDI with N-100 showed enhanced volume specific energy than using only N-100 in tensile test due to strain induced crystallization.     

The performance of the sludge pretreatment system with venturi tubes.

This research investigates the feasibility of the venturi cavitation system (VCS) for the sludge pretreatment to increase biodegradability. The performances of the VCS depended on the inclination angle of the venturi outlet, and better results obtained with 12 degrees than with 8 degrees or 15 degrees . Although it is energy efficient to use several venturies in series, the number of the venturies should be determined with detailed fluid dynamic calculations. The linear relationship between total solid (TS) concentration and the increases in soluble chemical oxygen demand (Delta SCOD) was observed for both wasted activated sludge (WAS) and primary sludge, which might be related to the better conditions for cavitation development at high TS concentrations even with higher viscosity. The VCS achieved better energy efficiency in terms of Delta SCOD/kJ compared to high-speed homogenizer (HSH). On the other hand, the VCS showed a similar energy efficiency for mixed sludge with 1.8% TS, but lower efficiency for WAS with 4% TS when compared to ultrasonic disintegration.