• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.7-13
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• 2003

The purpose of this study is to investigate the effect of the in-cylinder flows and different injection timings on fuel behavior in the cylinder of a GDI engine. Three different flows types induced by using masked port, unmasked port, and port deactivation were tumble, swirl&tumble, and high swirl respectively. LIEF technique was applied to investigate the mixture formation and fuel distribution at ignition time in the transparent engine with optical access through the piston top and upper part of cylinder liner. Injection timings of 180,90, and 60 degrees before TDC were examined. It was found that tumble flow was more effective on the homogeneous mixture formation than other flow and swirl flow transported more fuel vapor to the exhaust side at early injection mode, and swirl and swirl & tumble flow made fuel vapor concentrate around the cylinder center at late injection mode.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1252-1255
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• 2012

CRDI 디젤엔진을 산업용 엔진에 적용하여 최근 강화된 국내외의 배출가스 규제 조건을 충족시키기 위해 사용자가 연료의 분사시기와 분사량을 조절할 수 있는 CRDI ECU 제어 알고리즘을 개발하였다. CRDI 엔진 제어 ECU의 입력 요소 중 CKP와 CMP 센서를 이용하여 디젤 노킹 및 롱투스를 판별하는 알고리즘을 개발하여 분사시기와 분사량의 조절 시점을 결정하고, 엔진의 이상 유무를 판별할 수 있는 알고리즘을 개발하여 엔진의 밸런스를 조절함으로써 연비 향상 및 유해가스 저감을 효율적으로 개선할 수 있도록 하였다.

• Journal of Power System Engineering
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• v.16 no.3
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• pp.10-15
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• 2012

Recently we have a growing interest in environmental pollution and alternative energy. Diesel engine is generally used to produce the power on the ground and the sea. However, the combustion characteristics are changed on account of the wear of fuel system and the altered ambient condition of the combustion chamber by the increment of the engine operation hour. Therefore combustion characteristics on fuel injection timing are experimentally investigated to find out the optimum fuel injection timing in the case of the aged diesel engine using biodiesel blend oil. Cylinder pressure, rate of pressure rise, rate of heat release and combustion gas temperature are risen by the advancing fuel injection timing, while the exhaust gas temperature and soot emission level are decreased by the advancing of fuel injection timing. The least specific fuel oil consumption is indicated at BTDC $26^{\circ}$ CA on the 75%load and at 1800rpm.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.307-312
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• 2002

A study on the exhaust emissions of marine diesel engine with various fuel injection timing is performed experimentally .In this paper, fuel injection timing is changed from BTDC $14^{\circ}$ to $20^{\circ}$ by $2^{\circ}$ intervals, the experiments are performed at engine speed 1800rpm and from load 0% to 100% by 25% intervals, and main measured parameters are fuel consumption rate, Soot, NOx, HC and CO emissions etc. The obtained conclusions are as follows (1) Specific fuel consumption is indicated the least value at BTDC $18^{\circ}$ of fuel injection timing and it is increased in case of leading the injection timing. (2) Soot emission is decreased in case of leading fuel injection timing and it is increased in the form of convex downwards with increasing the load. (3) NOx emission is increased in case of leading fuel injection timing and it is increased in the form of straight line nearly with increasing the load. (4) HC and CO emissions are decreased in case of leading fuel injection timing and they are changed in the form of convex downwards with increasing the load.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.644-654
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• 2001

In this paper, an electronic control unit of the automobile engine for optimal fuel injection an spark timing control has been designed and developed. This system includes hardware and software for a precise control of fuel injection and ignition timing. Especially, the crank angle sensor provides two separate signals: One is the position signal (POS) which indicates 180 degree pulses per revolution, and the other is the reference signal (REF) that represents each cylinder individually. Consequently, the developed engine control system has been able to control fuel injection and ignition timing more quickly and accurately. Through the experiment, it has been found that the fuel injection duration and the position of MBT have been influenced by coolant temperature, air flow rate and engine speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.75-80
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• 2008

Biodiesel fuel(BDF) can be effectively used as an alternative fuel in diesel engine. However, BDF may affect the performance and exhaust emissions in diesel engine because it has different physical and chemical properties from diesel fuel such as viscosity, compressibility and so on. To investigate the effect of injection timing on the characteristics of performance and exhaust emissions with BDF in IDI diesel engine, it was applied the BDF derived from soybean oil in this study. The engine was operated at seven different injection timings from TDC to BTDC $12^{\circ}CA$ and six loads at a single engine speed of 1500rpm. When the fuel injection timing was retarded, better results were showed, which may confirm the advantages of BDF. The simultaneous reduction of smoke and NOx was achieved at some fixed fuel injection timings of an IDI diesel engine.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.367-375
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• 1986

On the hypothesis that the unstable intermediates yield by the pre-reaction of auxiliary fuel become an initiator or an explosive center which promotes the chain reaction of main fuel, various organic compounds below $C_{10}$ are injected as an auxiliary fuel prior to main injection. In the previous papers, the effects of the auxiliary fuel additions on the ignition delay period, the stability of flame, the NO concentrations in their exhaust gases have been investigated. In the present paper, to confirm where the most suitable location of lean pre-mixture for the combustion of main fuel is, and how the lean pre-mixture is contacted with main fuel, the effects of the injection timing of auxiliary fuel and the turbulence on combustion processes are investigated. Moreover, from the schlieren and color photographs of flame in the combution field, it could be found that the ignition nuclei are formed in a wider region of main spray, and that these ignition nuclei promote the development of flame, which results in the reduction of flaming duration.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1360-1368
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• 2005

This study investigates the characteristics of spray, such as evaporation rate and spray trajectory, for a 4-hole injector which is applied to a 4-valve motorcycle gasoline engine. Three dimensional, unsteady, compressible flow and spray within the intake-port and cylinder have been simulated using the VECTIS code. Spray characteristics were investigated at 6000 rpm engine speed. Furthermore, we visualized fuel behavior in the intake-port using a CCD camera synchronized with a stroboscope in order to compare with the analytical results. Boundary and intial conditions were employed by complete 1-D simulation of the engine using the WAVE code. Fuel was injected into the intake-port at two time intervals relative to the position of the intake valves so that the spray arrived when the valves were closed and fully open. The results showed that the trajectory of the spray was directed towards the lower wall of the port with injection against the closed valves. With open valve injection, a large portion of the fuel was lifted by the co-flowing air towards the upper half of the port and this was confirmed by simulation and visualization.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.196-204
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• 1996

The simplified dynamic models of the timer assembly in the diesel engine fuel injection system were developed. The first order system with time delay was assumed and the various parameters in this model were obtained by experimental data. These simplified dynamic models were used for the development of control algorithm of the injection timing control system. The PI control algorithm was modified to include the anti-windup property and disturbance compensation. This modified PI control algorithm was used for the control of the injection timing. Improved control accuracy and reduced control efforts were observed.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2186-2191
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• 2003

This study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in diesel engine. The effects of water induction through the air intake port were considered in IDI diesel engine in this study. The formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased with increased water amount. Also, NOx significantly decreased with increase in water amount. A simultaneous reduction in smoke and NOx emissions can be obtained when water is injected into the combustion chamber by retarding the fuel injection timing more than without water injection.