• 한국자동차공학회논문집
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• 제12권2호
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• pp.9-16
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• 2004

Close-coupled catalyst (CCC) can reduce the engine cold-start emissions by utilizing the energy in the exhaust gas. However, in case the engine is operated at high engine speed and load condition, the catalytic converter may be damaged and eventually deactivated by thermal aging. Excess fuel is sometimes supplied intentionally to lower the exhaust gas temperature avoiding the thermal aging. This sacrifices the fuel economy and exhaust emissions. This paper describes the results of an exhaust heat exchanger to lower the exhaust gas temperature mainly under high load conditions. The heat exchanger was installed between the exhaust manifold and the inlet of close-coupled catalytic converter. The exhaust heat exchanger successfully decreased the exhaust gas temperature, which eliminated the requirement of fuel enrichment under high load conditions. However, the cooling of the exhaust gas through the heat exchanger may cause the deterioration of exhaust emissions at cold start due to the increment of catalyst light-off time.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.153-162
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• 1997

The effects of tumble and swirl flows on the flame propagation were investigated experimentally in a 4-valve optical gasoline engine. The tumble flow patterns, generated by various intake ports of different entry angle; $25^{\circ}$ , $20^{\circ}$ and $15^{\circ}$ , were characterized under motored conditions with laser Doppler velocirnetry. Inclined tumble(swirl) flows were induced by three different swirl control valves. The initial flame propagation was visualized by an ICCD camera and its image were analyzed to compare the enflamed area and displacement of initial flames. It was found that there is a correlation between the stronger tumble during induction and turbulence levels at the time of ignition resulting in faster flame development. Inclined tumble was proved to be more beneficial than the pure tumble for faster and stable combustion under lean mixture conditions, which was confirmed by faster propagating flame images.

• 한국연소학회지
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• 제18권1호
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• pp.7-12
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• 2013

A quasidimensional program is developed for a four stroke cycle homogeneous GDI (Gasoline Direct Injection) engine. It includes models for spray, burning rate and chemistry to predict knock and emissions. With early injection a homogeneous GDI engine goes through spark ignited, turbulent premixed combustion as in PFI (Port Fuel Injection) engines. The cylinder charge is divided into unburned and burned zone with the latter divided into multiple zones of equal mass to resolve temperature stratification. Validation is performed against measured pressure traces, NOx and CO emissions at different load and RPM conditions. Comparison is made between an empirical knock model and predictions by the chemistry model in this work.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1157-1165
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• 2000

A classic examples of the abnormal combustions are the knock and misfire, which raise noxious performance and life of the engine. A heavy knock can also cause severe damages to the engine itself, which gives more reason why it must be detected and corrected. With the response of the today's requirements, we have researched the new diagnostic system which uses the breakdown voltage characteristics between electrodes of spark plug. This breakdown voltage depends on the pressure, temperature and even the shape and material of electrodes. But there is no data of breakdown voltage in case of using the spark plug as a electrodes. So, in this study, we show the breakdown voltage characteristic by pressure and temperature in constant volume bomb, which will make it possible to diagnose the engine combustion phenomenon.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.484-487
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• 1997

In this paper a simulation program for the powertrain control of a gasoline engine with automatic transmission is presented, The object-oriented programming approach has been pursued, and MATLAB/ SIMULINK was adopted for its environment. The purpose of the paper is to demonstrate the programmability of a control system in the object-oriented fashion so that the transferability of the objects is guaranteed. The program developed in the paper was applied to a gasoline engine and the mathematical models used in the paper were just adopted from the literature. It is shown that the simulation results and real experimental results coincide well. Therefore, it is expected that the program or objects made in the paper are useful for the automotive engineers when they design a new engine/transmission system or modify a part of existing system.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.273-275
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• 2014

An ammonia fuel system is developed and applied to both a spark ignition engine and a compression ignition engine to use ammonia as primary fuel in this study. Ammonia is injected separately into the intake manifold in liquid phase while gasoline or diesel is also injected as secondary fuel. As ammonia burns 1/6 time slower than gasoline or diesel, the spark or diesel injection timing is needed to be advanced to have better combustion phasing. The test engine showed quite high variation in the power output with large amount of ammonia. The final goal of the study is to implement a methodology to ignite ammonia-air mixture and have complete combustion without any use of the conventional fuels.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.97-100
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• 2014

The combustion and emission characteristics of propane and n-butane which are the main components of LPG were compared with gasoline. The experiment was performed in a stratified DISI engine under lean combustion conditions. Mixtures of propane and n-butane wre more homogeneous because propane and n-butane have better evaporation characteristics. As a result, combustion speeds of n-butane and propane were slower, and emission levels of NOx and PM were lower. However, in spite of better evaporation, PM from propane was higher.

• 동력기계공학회지
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• 제21권1호
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• pp.63-69
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• 2017

The combustion characteristics of gasoline and diesel were tested in a compression ignition engine. Both fuels were used with same common rail injection system. Combustion experiment showed that low load condition of 0.45 MPa IMEP (indicated mean effective pressure) was tested in metal and optical engines. The gasoline combustion showed higher hydrocarbon and carbon monoxide emissions but lower soot emission compared with diesel combustion. NOx emissions were very high at late injection timing but significantly decreased at early injection timing due to the lean combustion resulted from vigorous mixing process. Direct combustion visualization showed that the diesel combustion was dominated by diffusion combustion exhibiting soot incandescence and the gasoline combustion was mostly consisted of premixed combustion showing blue chemiluminescence.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.933-938
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• 2001

A 5-valve(intake 3-valve) engine has been developed to increase engine performance. These vehicles have a high power caused by the decrease of inertia mass of an intake valve and the increase of intake effective area. In this study, velocity profiles at near intake valves were inspected by using a two-color PIV and laser sheet method with tumble control valve(TCV). In addition, steady flow tests were performed to quantify tumble ratio on flow-fields generated with a TCV. These experimental results show that the tendency of the tunble ratio in intake 3-valve engine is different from the one in intake 2-valve engine. From this results, the intake flow characteristics around intake valves were made clear.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.28-35
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• 1999

In this study, investigation of transient knock characteristics in a spark-ignition engine has been carried out. The universal knock threshold values were found by a DFDD method and a NSDBP method which is a non-dimensional version of the SDBP method. Also modified NSDBP method could be used for transient knock detection. In a commercial ECU , spark timing was retarded from the steady -state spark timing during rapid throttle opening to avoid uncomfortable feeling and knock. Knock usually occurred just after the start of rapid throttle opening when spark timing was set, as values for the steady state condition. We found that air/fuel ratio deeply involved with the knock during transient condition. Due to the difference of initial heat release rate, knock occurred more easily at rich air/fuel ratio than at lean air/fuel ratio.