• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.500-507
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• 1989

The improvement of volumetric efficiency of air charging into combustion chamber is a primary requirement to obtain better mean effective pressure of an engine. Since parameters such as the air resistances in intake and exhaust flow passages, valve lift and valve timing influence greatly to the volumetric efficiency, it is very convenient and time saving if we can optimize these parameters by computation before we enter into long time fact finding engine tests. In this study we have developed a semi-empirical engine simulation program for the determinations of intake and exhaust valve timings, valve lifts, intake and exhaust port diameters in order to obtain highest volumetric efficiency. In this computation it requires only the measured variational pressures in intake and exhaust port. Using these variational pressures as an input data for our simulation program, we can calculate volumetric efficiency more accurately and can save computing time drastically. To confirm the validity of our simulation program we have made engine operation test in parallel and taken the experimental data. Comparing the computation result with the experimental data obtained through real engine test it has shown only the difference of 3%.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.58-67
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• 2003

An automotive engine cooling system is closely related with overall engine performances, such as reduction of fuel consumption, decrease of air pollution, and increase of engine life. Because of complex reaction between each component, the direct experiment, using a vehicle, takes high cost, long time, and slow response to the system change. Therefore, a computer simulation would provide the designer with an inexpensive and effective tool for design, development, and optimization of the engine cooling system over a wide range of operating conditions. In this work, it has been predicted the thermal performance of the engine cooling system in cases of stationary mode, constant speed mode, and city-drive mode by mathematical modelling of each component and numerical analysis. The components are engine, radiator, heater, thermostat, water pump, and cooling fans. Since the engine model is the most important, that is divided into eight sub-sections. The volume mean temperature of eight sub-sections are simultaneously calculated at a time. For detail calculation, the radiator and heater are also divided into many sub-sections like control volumes in finite difference method. Each sub-section is assumed to consist of three parts, coolant, tube with fin, and air. Hence it has been developed the simulation program that can be used in case of design and system configuration changes. The overall performance results obtained by the program were desirable and the time-traced tendencies of the results agreed fairly well with those of actual situations.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.62-74
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• 2001

In this study, the prediction of performances and emissions of the gasoline engine of a light passenger car has been accomplished. The method of characteristics including friction, heat transfer, area change and entropy gradients was used to analyze the flow in the intake and exhaust systems. For in-cylinder calculation, the single-zone model was adopted for the periods of the intake, exhaust, compression and the expansion of the burnt gas and the 2-zone expansion model was applied to the period of combustion process. The simulation program was verified by comparison with the experimental values both for the naturally aspirated engine and the turbocharged engine showing good agreements. Using the simulation program, multi-valve system and turbocharging were examined as a means of increasing engine Performances.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.605-616
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• 2001

Generally, there are two methods in researching internal combustion engines. One is by experimental research and the other is by computer simulation. The experimental research has many merits that researchers can get data for engine performance, but it has also some demerit of cost and time. If there is an engine simulation code with accuracy for the solution, it is very convenient to predict the performance and optimum design value of the engine. In this study, engine performance simulation program has been improved to predict the transient variation of properties of gas in cylinder, intake and exhaust manifolds, There total program code was developed to calculate the pressure, flame factor and turbulent intensity, As a result of present study, the authors could predicted the in-cylinder pressure, intake manifold pressure and the engine performance in various conditions. The authors also could easily prepare the tool if optimum design of manifold and in-cylinder geometry.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.1
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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 Mechanical Science and Technology
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• v.16 no.7
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• pp.975-985
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• 2002

This paper deals with theoretical model developed for analyzing the heat transfer of automotive cooling systems. The model has a modular structure which links various cooling system submodels. From the model, heat transfer rate of automotive cooling systems can be predicted, providing useful information at the early stages of the design and development. The aim of the study is to develop a simulation program for automotive cooling system analysis and a performance analysis program for analyzing heat exchanger. Heat release rate from combustion gas to coolant through the cylinder wall in engine cylinder was analysed by using an engine cycle simulation program. In this paper, details of each submodel are described together with the overall structure of the vehicle model.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.3
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• pp.59-65
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• 1999

To reduce the particulate matter and nitrogen oxides from diesel engine, many studies are proceeding and being accomplished practically. In this situation, LNG engine has important meaning as a clean fuel and alternative energy. In this reason, we try to understand the property of LNG fuel and predict the performance with using LNG engine simulation program and practical test. It could help to lead and apply practically LNG engine was studied in performance and other parameter related with engine performance and compared with current diesel engine. The simulation program was proved to be good in describing the experimental result. This means current heavy duty vehicle could be modified to LNG engine.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.535-550
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• 2016

Securing the safety and the reliability of liquid-propellant rocket engines (LREs) for space vehicles is indispensable as engines consist of many complex components and operate under extremely high energy-dense conditions. Thus, health monitoring has become a mandatory requirement, especially for the reusable LREs that are currently being developed. In this context, a dynamic simulation program based on MATLAB/Simulink was developed in the current research on the Space Shuttle Main Engine (SSME), a partly reusable engine. Then, a series of fault simulations using this program was conducted: at a steady state operating condition (104% Rated Propulsion Level), various simulated fault conditions were artificially injected into the simulation models for the five major valves, the pumps, and the turbines of the SSME. The consequent effects due to each fault were analyzed based on the time responses of the major parameters of the engine. It is believed that this research topic is an essential pre-step for the development of fault detection and diagnosis algorithms for reusable engines in the future.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.499-502
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• 2008

This paper presents on research findings of how Visual C++ program can be used to generate codes capable of performing ramjet engine simulation To understand the diversity and applicability of this tool an arbitrary ramjet model will be considered for which generated output values will be compared with those from a commercial program GASTURB 9 iterated under the same input parameters. Several governing thermodynamic equations will first be discussed in order that we understand the fundamental idea behind values printed out on the GUI. C++ compiler was chosen as a tool of use due to its availability, ease of use, ability to compute functions faster and uniquely possible to make a stand alone GUI executable in DOS mode. The program is developed in such a way that given the ambient flight conditions, burner exit temperature and several geometry areas the program generates its own input values used in the succeeding stations. A close resemblance of output values that define performance and thermodynamic state of the engine was realized between GASTURB 9 and using this code made from C++ compiler.