• Journal of the Korea Academia-Industrial cooperation Society
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• 제10권11호
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• pp.3253-3259
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• 2009

In this study, a computer simulation has been performed for the refrigeration cycle using mixed refrigerants in order to decrease the process stream temperature to $-20^{\circ}C$. Refrigerant supply temperature was assumed to be $-30^{\circ}C$ considering the temperature difference as $10^{\circ}C$ with process stream. Peng-Robinson equation of state model was selected for the computer simulation. A new alpha function proposed by Twu et al was used for an accurate prediction of pure component vapor pressure experimental data. One fluid mixing rules were used for the estimation of mixture vapor-liquid equilibria calculations. A commercial process simulator, PRO/II with PROVISION was utilized for the simulation of the overall refrigeration process. In order to minimize the compressor power consumption, we have optimized the two-stage compression system by varying the first stage compressor outlet pressure. Finally, we could obtain the minimum total power 755.7kW at the first stage compressor outlet pressure, 6 bar.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제32권9A호
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• pp.931-939
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• 2007

This paper describes the system which automatically generates instruction-set simulators cores using the SMDL. SMDL describes structure and instruction-set information of a target DSP machine. Analyzing behavioral information of each pipeline stage of all instructions on a target ASIPS, the proposed system automatically generates a cycle-accurate instruction set simulator in C++ for a target processor. The proposed system has been tested by generating instruction-set simulators for ARM9E-S, ADSP-TS20x, and TMS320C2x architectures. Experiments were performed by checking the functions of the $4{\times}4$ matrix multiplication, 16-bit IIR filter, 32-bit multiplication, and the FFT using the generated simulators. Experimental results show the functional accuracy of the generated simulators.

• Transactions of the Korean Society of Automotive Engineers
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• 제13권3호
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• pp.1-9
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• 2005

In this paper, an operation algorithm and a performance simulator are developed for a 42-volt ISG vehiclewhich consists of 5 kW ISG, 2500cc IC engine, torque converter and 4 speed automatic transmission. Modularapproach using MATLAB Simulink is used to construct a dynamic model of the vehicle powertrain which is obtainedfrom each component such as engine, battery, ISG, torque converter, etc.. An operation strategy for a 42-volt ISG vehicle including the function such as engine idle stop and regenerative braking is proposed. Performance simulator is developed based on the dynamic models of the powertrain. It is found from the simulation results that fuel economy can be improved as much as 6 percent for FTP75 driving cycle mostly owing to the engine idle stop.

• Journal of the Korean Society of Safety
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• 제17권4호
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• pp.94-100
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• 2002

As the use of automatic handling equipment for sensitive semiconductor devices is rapidly increased, manufacturers of electronic components and equipments need to be more alert to the problem of electrostatic discharges(ESD). In order to analyze damage characteristics of semiconductor device damaged by ESD, this study adopts a new charged-device model(CDM), field-induced charged model(FCDM) simulator that is suitable for rapid, routine testing of semiconductor devices and provides a fast and inexpensive test that faithfully represents ESD hazards in plants. High voltage applied to the device under test is raised by the field of non-contacting electrodes in the FCDM simulator, which avoids premature device stressing and permits a faster test cycle. Discharge current and time are measured and calculated. The characteristics of electrostatic attenuation of domestic semiconductor devices are investigated to evaluate the ESD phenomena in the semiconductors. Also, the field charging mechanism, the device thresholds and failure modes are investigated and analyzed. The damaged devices obtained in the simulator are analyzed and evaluated by SEM. The results obtained in this paper can be used to prevent semiconductor devices form ESD hazards and be a foundation of research area and industry relevant to ESD phenomena.

• Journal of Drive and Control
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• 제11권2호
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• pp.16-21
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• 2014

The purpose of this paper is to construct a control algorithm for improving the driving efficiency of 4-wheel-drive in-wheel electric vehicles. The main parts of the vehicle were modeled and the input-output relations of signals were summarized using MATLAB/Simulink. A performance simulator for 4-wheel-drive in-wheel electric vehicles was developed based on the co-simulation environment with a commercial dynamic behavior analysis program called Carsim. Moreover, for improving the driving efficiency of vehicles, a torque distribution algorithm, which distributes the torque to the front and rear wheels, was included in the performance simulator. The effectiveness of the torque distribution algorithm was validated by the SOC simulation using the FTP-75 driving cycle.

• Journal of Energy Engineering
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• 제5권1호
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• pp.34-41
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• 1996

The heat of evaporation (cold energy) of LNG is the energy consumed in the production of LNG. This energy amounts to 14% of the NG. In Pyungtak LNG terminal, it is about 96 MW in 1993. In order to utilize the cold energy, the cold power generation systems are investigated: The Rankine cycle using the low temperature energy, the partial expansion cycle using the pressure energy, and the Linde process which is a combined cycle of the Rankine and the partial direct expansion cycle. The commercial simulator, ASPEN Plus, is used. The conceptual design data are obtained from the current facilities of the Pyungtak LNG terminal. The performances of three systems are evaluated. The amount of electric power ranges iron 3 MW to 6MW. The optimum energy efficiency is about 37%. The optimum design conditions are obtained for the partial direct expansion (PDE) cycle. The performance of the PDE cycle is supposed to be comparable to that of the Rankine cycle if the areas of the total heat exchanger of the both cycle are equal.

• Journal of the Korean Institute of Intelligent Systems
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• 제10권6호
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• pp.584-590
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• 2000

Urban traffic situations are extremely complex and highly interactive. The multi-agent systems approach can provide a new desirable solution. Currently, a traffic simulator is needed to understand and explore the difficulties in an agent-oriented traffic control. This paper presents an agent-oriented fuzzy logic controller for multiple crossroads simulation. A fuzzy logic control simulation with variables of arrival, queue, and traffic volume could alleviate traffic congestion. We developed an agent-oriented simulator suitable for traffic junctions with η$\times$η intersections in Visual C++. The proposed method adaptively controls the cycle of traffic signals even though the traffic volume varies. The effectiveness of this method was shown through simulation of multiple intersections.

• Journal of the Korean Institute of Telematics and Electronics
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• 제14권2호
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• pp.17-27
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• 1977

The special mini-computer was designed with the one-bus line systems employing the integrated circuits, and was studied by the method of easily making the compiler in 16 bits with each instruction fields. When the 160 nano seconds for a fundamental cycle were used, the optimum operating time for a TTL IC was equal to the access time for the main memory unit. As a result, the circuits were very simple, and the simulator functioned well for all the programs.

• Proceedings of the KSME Conference
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• 대한기계학회 2004년도 춘계학술대회
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• pp.394-399
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• 2004

In order to secure the safety of power steering system, it is necessary to perform the strength and the fatigue analysis of pulley in this paper. The applied stress distribution of the pulley subject to combined loads condition was obtained using finite element analysis. Based on these results, the fatigue life of the pulley with the variation of the fatigue strength was evaluated using durability analysis simulator. The optimal hole size to improved the safety of the pulley was investigated using parametric study. Moreover, the predicted fatigue life cycle with the simulator was verified by experimental tests.

• Journal of Korea Water Resources Association
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• 제48권5호
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• pp.321-330
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• 2015

In recent, the impacts of urbanization on hydrology and water quality can be minimized with the use of Low Impact Development (LID) practices in urban areas. But, there are no ways to verify or to show the quantitative effectiveness with LID practices. This study designed and developed to perform experiments in natural or artificial representation of hydrological cycle, which is called rainfall-runoff simulator to be able to quantify factors in hydrological system. This simulator was applied to a pervious pavement block. The study conducted analysis of effectiveness for a pervious pavement block by comparing the results with a general pavement block. The result from the pervious pavement block showed remarkably reduction effect on surface runoff with increase of rainfall intensity and more duration time. Also, the simulator was possible to control no surface runoff by a rainfall intensity at 50 mm/hr for an hour. The research indicated possibility and effectiveness for LID practices. This might be widely available to apply to LID practices verification. Therefore, the study is possible to make use of practical standards on fundamental studies.