• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.106-112
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• 2000

The purpose of this paper is to study on the control of the engine idle speed under sudden A/C load which is one of the most severe disturbances on engines. Three types of the closed-loop controller are developed for the stable engine idle speed control. The input of the controller is an error of rpm. The output of the controller is an ISCV duty cycle. The anticipation delay is considered to deal with the delay time of the air mass in engine. The PID, Fuzzy and PID-type Fuzzy controllers with the anticipation delay have improved the engine idle speed condition more than current ECU map table under the A/C load.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.680-686
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• 2004

Recently, the application of variable geometry turbocharger (VGT) to the high speed direct injection (HSDI) diesel engine has gained more and more interest in automotive industry. A steady state experimental investigation has been undertaken on a 1.5L HSDI diesel engine to verify the benefits of VGT comparing to the standard engine having a waste gate turbocharger (WGT). Specifically, part load performances (e.g., fuel economy and emission) have been investigated under various vane angles of the VGT. The results show that the real exhaust gas recirculation (EGR) rate as well as the pumping loss is very important to improve break specific fuel consumption (BSFC). It was previously known that the pumping loss only is a main parameter. In addition, the trade-off relationship between BSFC and NOx according to boost pressure, and the decreasing tendency of NOx with increasing real EGR rate have been verified. 1-D numerical analysis also has been performed, and the numerical results are in good agreement with experimental results.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.47-50
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• 2011

E/R bulkhead is watertight bulkhead between engine room and cargo hold. So, it must have sufficient strength about cargo load of aft hold. Especially, partial stringer deck between tank top and $2^{nd}$ deck of engine room must have sufficient strength because it has function of primary supporting member. Generally, cargo hold structure is verified through the direct calculation as finite element analysis of cargo hold, but engine room structure doesn't perform it. Therefore, we have performed finite element analysis of engine room stringer deck which considered cargo hold load. And then, it will be able to apply similar ship design.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.3-10
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• 1998

In general, the stratified charge for direct injection gasoline engine should be introduced to achieve ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, a reflector was adapted on cylinder head. An installation of the reflector in front of the injector nozzle leads the mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally ich to ignite while the lean mixture is wholly introduced into the combustion chamber. In this paper, the characteristics of combustion is analyzed with the variations of injection pressure and load in a stratified-charge direct injection single cylinder gasoline engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.180-186
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• 2009

To meet the NOx limit without a penalty of fuel consumption, urea SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal $NH_3$ slip. In this study, as a basic research to develop an algorithm for urea injection control, the characteristics of engine out NOx emission and behavior of NOx reduction during steady-state and transient conditions were investigated using 2L DI diesel engine. Test results show that on increasing the catalyst temperature the variations in the outlet NOx concentration are faster and maximal allowable $NH_3$ storage exponentially decreases. For change from a low to high engine load, it can be seen that a few seconds after load-step is required to reach full NOx conversion and the adsorbed amount of $NH_3$ at lower temperature desorb during the next temperature increase, causing $NH_3$ slip. Engine out NOx emission needs to be corrected because NOx emissions just after step load is lower than that of steay state condition.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.527-534
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• 2006

Modern passenger cars with diesel engines are equipped with DOC(diesel oxidation catalyst) for the purpose of reducing HC and CO in the exhaust stream. Cold start exhaust emissions pose troubles here as on gasoline engine vehicles. As a result, some of the diesel passenger cars roll off todays the assembly lines with WCC(warm-up catalytic converter). Oxidation characteristics of the particulates in WCC is analyzed in this study by EEPS(engine exhaust particulate size spectrometer). The maximum number of PM is found to come out of WCC in sizes near 10nm when an HSDI diesel engine is operated under the conditions of high speed and medium to heavy load. When the temperature of the WCC exceeds $300^{\circ}C$, the number of PM smaller than 30 nm in diameter sharply increases upon passing through the WCC. Total mass of emitted PM gets reduced downstream of the WCC under low speed and light load conditions due to adsorption of PM onto the catalyst. Under conditions of high speed and medium to heavy load, the relatively large PM shrink or break into fine particles during oxidation process within the WCC, which results in more mass fraction of fine particles downstream of the WCC.

• Journal of Hydrogen and New Energy
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• v.24 no.6
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• pp.472-479
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• 2013

A free piston linear engine could be operated under HCCI combustion due to its variable compression ratios. To obtain HCCI combustion, the free piston linear engine needs a high compression ratio to achieve auto-ignition of the fuel/air mixture. In this study, an idea for obtaining a high compression ratio using the transition from SI combustion to HCCI combustion was proposed. The fuel used in this study is hydrogen, which is considered to be an environmentally friendly fuel. Besides, the effects of key parameters such as equivalence ratio (${\phi}$), load resistance ($R_L$) and intake temperature ($T_{in}$) on the SI-HCCI transition were numerically investigated. The simulation results show that the SI-HCCI transition is successful without any significant reduction of in-cylinder pressure as the intake temperature is increased from $T_{in}$=300K (SI mode) to $T_{in}$=450K (HCCI mode), while the load resistance and equivalence ratio are retained respectively at $R_L=120{\Omega}$ and ${\phi}$=0.6 in both SI mode and HCCI mode.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.14-20
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• 2003

The minimization of valve and seat insert wear is a critical factor in the pursuit of engine performance improvement. In order to achieve this goal, we have developed a new simulator, which can generate and control high temperatures up to $900^{\circ}C$ and various speeds up to 80Hz during motion, just like an actual engine. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity. The objective of this work focuses on the different degrees of wear from two different test speeds (10Hz & 25Hz). For this study, the temperature of the outer surface of the seat insert was controlled at $350^{\circ}C$, the cycle number was 2.1$\times$106, and the test load was 1960N. The wear depth and surface roughness were measured before and after the testing using a confocal laser scanner. It was found that a higher speed (25Hz) causes more wear than a lower speed (10Hz) under identical test conditions (temperature, cycle number and test load). In the wear mechanism adhesive wear, shear strain and abrasive wear could be observed.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.80-89
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• 1998

The residual gas in an spark-ignition engine is one of important factors on emissions and performance such as combustion stability. With high residual gas fractions, flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters. In the present study, the quantitative measurement technique of residual gas fraction was studied by using Fast Response Flame Ionization Detector(FRFID). The measuring technique and model for estimation of residual gas fraction were reported in this paper. By the assuming that the raw signal from FRFID saturates with the same slope for firing and misfiring cycle, in-cylinder hydrocarbon(HC) concentration can be estimated. Residual gas fraction can be obtained from the in-cylinder HC concentration measured at firing and motoring condition. The developed measurement and calibration procedure were applied to the limited engine operating and design condition such as intake manifold pressure and valve overlap. The results show relevant trends by comparing those from previous studies.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.3
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• pp.256-263
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• 2021

In this study, blending oils of diesel oil and butanol were used as fuel oil for diesel engine to measure combustion pressure, fuel consumption, air ratio and exhaust gas emission due to various operating conditions such as engine revolution and torque. Using these data, the results of analyzing the engine performance, combustion characteristics and exhaust emission characteristics such as NOx (nitrogen oxides), CO₂ (carbon dioxide), CO (carbon monoxide) and soot were as follows. The fuel conversion efficiency at each load was highest when driven in the engine revolution determined by a fixed pitch propeller law. Except 30% butanol blending oil, fuel conversion efficiency of the other fuel oils increased as the load increased. Compared to diesel oil, using 10% and 20% butanol blending oil as fuel oil was advantageous in terms of thermal efficiency, but it did not have a significant impact on the reduction of exhaust gas emissions. On the other hand, future research is needed on the results of the 20% butanol blending oil showing lower or similar levels of smoke concentration and carbon monoxide emission rate other than those types of diesel oil.