• 설비공학논문집
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• 제10권2호
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• pp.202-216
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• 1998

A computer simulation for the performance analysis of automobile air conditioning components is carried out for the various operating conditions. The automobile air conditioning system consists of laminated type evaporator, swash plate type compressor, parallel flow type condenser, externally equalized thermostatic expansion valve and receiver drier. The overall heat transfer coefficient and the pressure drop in laminated type evaporator were obtained through experiments. In parallel flow type condenser, the performance analysis computer program using the empirical equation for heat transfer coefficient has been developed and the results are compared with experimental results. A model for matching the performance analysis programs of respective components .of automobile air conditioning system is introduced. Further, the effects of varying condenser size and refrigerant charge on the performance of automobile air conditioning system are discussed clearly.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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• pp.110-115
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• 2001

Today, effective utilization of sophisticated networks greatly influences the activities of a business, making performance evaluations of computer network systems a necessity, We have developed a special computer network simulator capable of automatically generating a model based on data accumulated by a network analyzer to guide the user in selecting ideal parameters. The simulator was developed to provide user-friendly analysis for engineers involved in the actual network design. This paper gives an overview of the simulator and describes an example application of evaluating a network design that anticipates the future increase in traffic for a company introducing voice over frame relay (VoFR) into a wide area network (WAW).

• 한국컴퓨터산업학회논문지
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• 제4권12호
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• pp.1033-1042
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• 2003

본 논문에서는 컴퓨터 시뮬레이션에 의한 인구예측을 통계모형을 써서 연구하였고 더불어 경제인구를 예측하였다. 과거의 인구를 토대로 하여 미래의 인구를 예측한다는 것은 불확실한 상황이 많이 개입되어 있기 때문에 매우 어려운 문제이다. 또한 예측이 되었다 하더라도 급변하는 세계적인 문화 및 국내의 문화적인 정서의 흐름에 따라서 많은 변화가 예상되므로 경제인구 예측을 적중하기에는 더 더욱 어려운 것이다. 인구 예측에 있어서 과거의 자료인즉, 1960년도부터 1990년도까지 센서스 인구를 이용하여 Box ＆ Jenkins가 개발한 ARIMA 모형을 써서 미래 2021년도까지의 인구를 각각 표나 부록에 나타난 것처럼 경제인구를 예측하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.206-211
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• 1992

A mathematical model of the blow-down type wind tunnel is developed in order to design the controller which controls the stagnation pressure being used to obtain the setpoint Mach Number. The motion of compressible fluids in the tunnel is modeled using the one-dimensional gasdynamics. The time responses of the wind tunnel states, such as pressures, mass flow rates, and valve open area, are investigated by digital computer simulation. By the simulation study it is shown that the real blow-down wind tunnel can be simulated by the obtained mathematical model.

• Journal of Power Electronics
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• 제11권1호
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• pp.51-58
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• 2011

In this paper, a function model of back-to-back PWM converters, based on the switching function, is developed for simplified simulation of power electronic application systems. For the function model, the PWM power switches are represented by dependent power sources. By using the proposed function model, the computer memory and the run time required for the simulation of power circuits can be significantly reduced. It is shown that the simulation results generated from the function models are almost the same as the ones obtained by using the switching power device model.

• 한국정밀공학회지
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• 제10권3호
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• pp.69-80
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• 1993

It is important to prevent roll failure in hot rolling process for reducing maintenance coat and production loss. Roll material and rolling conditions such as the roll force and torque have been intensively investigated to overcome the roll failures. In this study, a computer roll life prediction system under working condition is developed and evaluated on IBM-PC level. The system is composed and fatigue estimation models which are stress analysis, crack propagation, wear and fatigue estimation. Roll damage can be predicted by calculating the stress anplification, crack depth propagation and fatigue level in the roll using this computer model. The developed system is applied to a work roll in actual hot rolling process for reliability evaluation. Roll failures can be diagnosed and the propriety of current working condition can be determined through roll life prediction simulation.

• 한국농공학회논문집
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• 제51권2호
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• pp.43-49
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• 2009

Many researcher uses simulation techniques for understanding the phenomenon and expecting the response. Simulation techniques have many advantages which is less time-consuming, easy to control constraints, and cheaper than experimental study. However Researches usually are not good at programming the model, it's hard to implement simulation model using computer language. They use spreadsheet program like Microsoft $excel^{TM}$ Although a spreadsheet program is good for modeling, it's cumbersome to describe expressions which consist of not variable name but location indicator. This study suggests the program which helps researcher developing model using graphical interface and variable name. For verifying usability, the model which is implemented by developed modeler were compared with by spreadsheet program.

• Journal of Power Electronics
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• 제13권3호
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• pp.429-436
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• 2013

Online simulations are utilized to reduce time and cost in the development and performance optimization of plug-in hybrid electric vehicle (PHEV) and electric vehicles (EV) systems. One of the most important factors in an online simulation is the accuracy of the model. In particular, a model of a battery should accurately reflect the properties of an actual battery. However, precise dynamic modeling of high-capacity battery systems, which significantly affects the performance of a PHEV, is difficult because of its nonlinear electrochemical characteristics. In this study, a dynamic model of a high-capacity battery cell for a PHEV is developed through the extraction of the equivalent impedance parameters using electrochemical impedance spectroscopy (EIS). Based on the extracted parameters, a battery cell model is implemented using MATLAB/Simulink, and charging/discharging profiles are executed for comparative verification. Based on the obtained results, the model is optimized for a high-capacity battery cell for a PHEV. The simulation results show good agreement with the experimental results, thereby validating the developed model and verifying its accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1141-1146
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• 1993

The problem of tension control in metal-strip processing line is discussed. A new mathematical dynamic model which relates tension change, motor-speed change and roll-gap change is developed. Through the computer simulation of this model, parameter sensitivity, the tension transfer phenominon, and static and dynamic characteristics of strip tension were studied. Guidelines are developed to help one selecting locations of the master-speed drive in multi-drive speed control for tension adjustment and reducing the effect of interaction between tension and roll gap control.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권4호
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• pp.220-228
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• 2002

The cool-down performance after soaking is very important in an automotive air-conditioning system and is considered as a key design variable. Therefore, transient characteristics of each system component are essential to the preliminary design as well as steady-state performance. The objective of this study is to develop a computer simulation model and ostinato theoretically the transient performance of an automotive air-conditioning system. To do that, the mathematical modelling of each component, such as compressor, condenser, receiver/drier, expansion valve, and evaporator, is presented first of all. The basic balance equations about mass and energy are used in modelling. For detailed calculation, condenser and evaporator are divided into many sub-sections. Each sub-section is an elemental volume for modelling. In models of expansion valve and compressor, dynamic behaviors are not considered in this analysis, but the quasisteady state ones are just considered, such as the relation between mass flow rate and pressure drop in expansion device, polytropic process in compressor, etc. Also it is assumed that there are no heat loss and no pressure drop in discharge, liquid, and suction lines. The developed simulation model is validated by comparing with the laboratory test data of an automotive air-conditioning system. The overall time-tracing properties of each component agreed well with those of test data in this case.