• 한국군사과학기술학회지
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• 제6권1호
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• pp.30-38
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• 2003

The measurement on the working gas flow in the closed cycle diesel engine is insufficient to Identify its operating condition because of lack of sensors available. For this reason, the determination of optimum operating condition and controller parameters requires heavy experimental efforts. A simulation program is developed to minimize the experimental efforts. For the development of the simulation program, mathematical models are derived based on the physical laws and linear regression. The validity of the simulation program is demonstrated using the measured data of the closed cycle diesel engine.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2000년도 제15회 학술강연회논문초록집
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• pp.16-16
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• 2000

항공기 가스 터어빈 엔진의 공기 열역학적 특성을 분석하고 예측하기 위한 simulation program이 KARI-ONEP (Korea Aerospace Research Institute -ON-design Engine Program)의 이름으로 개발되었다. 이 program은 on-design cycle analysis를 위한 것으로서 program의 수행에 필요한 엔진 구성요소별 특성 치 data인 input data를 생성하는 input data generator인 KARI-ONEPi와 cycle analysis를 수행하는 주 program인 KARI_ONEPe로 구성이 되어있다.(중략)

• 한국자동차공학회논문집
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• 제9권1호
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• pp.63-74
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• 2001

In this study, a cycle simulation program of a Unit-Injection(UI) system was developed to estimate the injection performance of newly designed injection system. A fundamental theory of the simulation program is based on the conservation law of mass. Loss of fuel mass in the system due to leakage, compressibility effect of the liquid fuel and friction loss in the control volume was considered in the algorithm f the program. For the evaluation of the simulation program developed, the experimental result which was offered by the Technical Research Center of Doowon Precision Industry Co. was incorporated. Two main parameters; the maximum pressure in the plunger chamber and total fuel mass(kg) injected into the engine cylinder per cycle, were measured and compared with the simulation results. It was found that the maximum error rate of the simulation result to the experimental output was less than 3% in the rated rotational speed (rpm) range of the plunger cam.

• 한국산학기술학회논문지
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• 제3권3호
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• pp.210-215
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• 2002

본 연구에서 R410A를 사용하는 멀티에어컨 시스템의 성능(성능계수, 용량, 소비전력 등)을 정상 상태에서 모사할 수 있는 Multi_Cycle이라 명명된 컴퓨터 모사 프로그램을 개발하였다. 컴퓨터 시뮬레이션 프로그램을 검증하기 위해서 일련의 사례 연구를 수행하였으며, 이에 대해서 설명하였다. Mulli_Cycle은 실내기, 실외기, 압축기와 팽창 밸브 모사를 위한 부프로그램 및 냉매와 습공기의 열역학적 물성치와 전달 물성치 예측을 위한 부프로그램으로 구성되어있다. 멀티에어컨 사이클을 구성하고 있는 각 유닛의 복잡한 조자조건과 다양한 종류의 냉매를 고려해야 하는 멀티에어컨의 성능 분석시 Multi_Cycle의 사용은 많은 도움이 될 것이다. 나아가, Multi_Cycle은 멀티에어컨 시스템을 최적화하고, 경제적이고 효율적인 운전 조건을 확립하는데 매우 유용한 도구가 될 수 있을 것이다. Multi_Cycle의 주시뮬레이션 코드는 Digital Visual Fortran으로 프로그램 되었으며 그래픽 사용자 인터페이스(GUI)는 Visual Basic으로 프로그램 되었다.

• 한국산학기술학회논문지
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• 제12권6호
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• pp.2888-2897
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• 2011

본 연구에서 개발된 정상상태 사이클 모사 프로그램을 통해 이산화탄소를 사용하는 지열 히트펌프 시스템의 성능을 고찰하였다. 내부열교환기를 포함하지 않는 기본 히트펌프 사이클의 성능에 대한 다양한 운전변수들의 영향을 조사하기 위해 매개변수 연구를 수행하였다. 시뮬레이션 프로그램은 실내기, 실외기, 압축기, 팽창밸브를 모사하는 포트란 서브루틴과 비주얼 베이식을 사용해 프로그램된 입력을 위한 전처리, 출력을 위한 후처리 프로세서를 포함하는 그래픽 인터페이스로 구성되어 있다. Refprop V6.01을 사용하여 이산화탄소의 열역학적 물성치와 상평형 거동을 계산하였다. 모사결과들의 신뢰성은 사례연구를 통한 실험데이터와의 비교를 통해 검증하였다. 본 연구에서 개발된 사이클 모사 프로그램은 이산화탄소 지열 히트펌프 시스템의 경제적이면서도 효율적인 운전조건들을 결정하고 최적화하는 데 있어 유용한 도구가 될 수 있을 것이다.

• 한국기계가공학회지
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• 제14권1호
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• pp.1-8
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• 2015

Productivity of machining using machine tools is affected by cutting conditions such as cutting speed, feedrate and depth. However, undesirable conditions that lengthen the machining cycle and shorten the tool life occur frequently because determination of cutting condition is known to depend on human experience. This paper presents a method of cycle reduction by removing undesirable conditions. For cycle reduction, maximum cutting load is determined using commercial FEM simulation code. The feedrate in the NC program is altered based on a predetermined cutting load value. To make a decision on the proposed effectiveness, a simulation is performed for the brake hub parts of an automobile. From the evaluation, it was found that the cycle reduction was under 15%.

• 한국산업융합학회 논문집
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• 제3권3호
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• pp.265-273
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• 2000

Basic simulation program for Vuilleumier cycle heat pump was developed that can use precise VMHP design and analysis. VMHP system was divided 11 sections in simulation. Simulation was used adiabatic model analysis and that considered with heat transfer performance for heat exchanger, regenerator loss, conduction loss, shuttle loss, pumping loss and pressure loss by flow friction. Specially, friction loss of connection pipe between heat compression side and heat pump side, leakage of rod seal and piston seal was considered in the analysis.

• 설비공학논문집
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• 제11권4호
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• pp.499-510
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• 1999

A computer program was developed for simulating performance(capacity, power consumption and etc.) of air-conditioners using compressor, fin-tube heat exchanger and capillary tube. The program consists of five modules, condenser, evaporator, compressor, capillary tube simulation modules and properties modules of refrigerant and moist air, The present program is focused on R22 only, however can be easily extended for other refrigerants such as R407C and R410A just by adding property modules. The compressor simulation module utilizes performance maps supplied by manufacturers-map-based model. The condenser and evaporator simulation modules are modeled using tube-by-tube method. Simulation results(capacity and power consumption) were compared with calorimeter test results of actual air-conditioners of window and split types, where more than 82% of the data lied within ${\pm}5$% of the predicted results.

• Journal of Advanced Marine Engineering and Technology
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• 제8권1호
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• pp.17-36
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• 1984

Since 1973, the competition on the development of fuel saving type internal combustion engines has become severe by the two times oil shock, and new type engines are reported every several months. Whenever these new type engines are developed, new designs are required and they will be offered in the market after performing the endurance test for a long time. But the engine market is faced with a heavy burden of finance, as the developing of a new engine requires tremendous expenses. For this reason, the computer simulation method has been lately developed to cope with it. The computer simulation method can be available to perform the reasonable research works by the theoretical analysis before carrying out practical experiments. With these processes, the developing expenses are cut down and the period of development is curtailed. The object of this study is the development of simulation computer program for the small naturally aspirated four-stroke diesel engine which is intended to product by the original design of our country. The process of simulation is firstly investigated for the ideal engine cycle, and secondly for the real engine cycle. In the ideal engine cycle, each step of the cycle is simulated by the energy balance according to the first law of thermodynamics, and then the engine performance is calculated. In the real cycle imulation program, the injection rate, the preparation rate and the combustion rate of fuel and the heat transfer through the wall of combustion chamber are considered. In this case, the injection rate is supposed as constant through the crank angle interval of injection and the combustion rate is calculated by the Whitehouse-Way equation and the heat transfer is calculated by the Annand's equation. The simulated values are compared with measured values of the YANMAR NS90(C) engine and Mitsubishi 4D30 engine, and the following conclusions are drawn. 1. The heat loss by the exhaust gas is well agree with each other in the lower load, but the measured value is greater than the calculated value in the higher load. The maximum error rate is about 15% in the full load. 2. The calculated quantity of heat transfer to the cooling water is greater than the measured value. The maximum error rate is about 11.8%. 3. The mean effective pressure, the fuel consumption, the power and the torque are well agree with each other. The maximum error is occurred in the fuel consumption, and its error rate is about 7%. From the above remarks, it may be concluded that the prediction of the engine performance is possibly by using the developed program, although the program needs to reform by adding the simulation of intake and exhaust process and assumping more reliable mechanical efficiency, volumetric efficiency, preparation rate and combustion rate.

• Journal of Advanced Marine Engineering and Technology
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• 제13권3호
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• pp.64-71
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• 1989

In this paper, a computer program for simulation of 4 cycle diesel engines including intake and exhaust manifold system is developed. The wave action theory is applied for optimization of the intake and exhaust manifold system. The calculation results of this computer program is finely accurate and agreed well with experimental results. Accordingly, it is recognized that the developed computer program can be utillized very usefully for the design of intake and manifold system. And then, influential factors of the engine performance in the design of intake manifold is numerically investigated by the calculation only. As the results it is concluded that the inertia one of the dynamic effects on the intake and exhaust maninfold affects mainly the engine performance and the pulsation one is a side effect.