• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.117-123
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• 1994

This paper describes the effect of air assisted fuel injection system(AAI) using compressed air to improve the performance of lean combustion engine. AAI is designed to promote fuel atomization and intake flow. In order to investigate the performance of engine with AAl, experiments are conducted varying the engine revolution speed, lean air-fuel ratio and intake manifold pressure. Compared with the original engine, the performance of the engine with MI is improved as the air-fuel mixture becomes leaner or the engine load becomes lower. The descreasing rate of BSFC is propotional to the relative air-fuel ratio and the lean misfire limit extended more than 0.2 relative airfuel ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.589-595
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• 2003

DME(Dimethyl ether) is an oxygenated fuel with a octane number higher than that of diesel oil. It meets the ULEV emission regulation and reduces the smoke to almost zero when used in a diesel engine. In the present study, engine performance and exhaust emissions were investigated with a conventional DI diesel engine which has a jerk type injection pump. Test results showed that the power with DME were almost same as that of pure diesel oil, and the brake thermal efficiency increased a little. Also, smoke index from DME engine showed nearly zero level, but NO$_{x}$ was increased compare to diesel oil.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.1-9
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• 2008

In this paper, an energy regeneration algorithm is proposed to make the maximum use of the regenerative braking energy for a parallel hybrid electric vehicle(HEV) equipped with a continuous variable transmission(CVT). The regenerative algorithm is developed by considering the battery state of charge(SOC), vehicle velocity and motor capacity. The hydraulic module consists of a reducing valve and a power unit to supply the front wheel brake pressure according to the control algorithm. In order to evaluate the performance of the regenerative braking algorithm and the hydraulic module, a hardware-in-the-loop simulation (HILS) is performed. In the HILS system, the brake system consists of four wheel brakes and the hydraulic module. Dynamic characteristics of the HEV are simulated using an HEV simulator. In the HEV simulator, each element of the HEV powertrain such as internal combustion engine, motor, battery and CVT is modelled using MATLAB/$Simulink^{(R)}$. In the HILS, a driver operates the brake pedal with his or her foot while the vehicle speed is displayed on the monitor in real time. It is found from the HILS that the regenerative braking algorithm and the hydraulic module suggested in this paper provide a satisfactory braking performance in tracking the driving schedule and maintaining the battery state of charge.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.9-17
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• 1994

In this study, a shifting algorithm of CVT was suggested for the two(2) driving modes : (1) power mode and (2) economy mode. Shifting algorithm must be obtained to make the engine run on the optimum operating line for the desired performance of the vehicle. Optimum operating lines of the engine were obtained by connecting the shortest way of the iso-power lines for the power mode and by connecting the shortest way of the BSFC curves for the economy mode. Also dynamic model of CVT vehicle was derived considering the throttle and the brake operation. By using the shifting algorithm and the CVT vehicle model, numerical simulations were performed to estimate the performance of CVT. Simulation results showed that comparing the performance of the conventional 4-speed automatic transmission, acceleration performance of the CVT vehicle was almost same with the AT vehicle for the power mode and the fuel economy of CVT was 14% superior than that of AT for the economy mode.

• Journal of Biosystems Engineering
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• v.34 no.3
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• pp.135-139
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• 2009

Harmful exhaust emissions of diesel engines are recognized as main causes of air pollution in these days. But, the direct injection diesel engine is widely used for sake of minimization on energy consumption. Because biodiesel fuel is a renewable and alternative fuel for a diesel engine, its usability is expanded. To investigate the effect of biodiesel fuel(extracted from rapeseed oil) on the characteristics of performance and exhaust emissions in an agricultural diesel engine, the biodiesel fuel derived from rapeseed oil was applied in this study. Smoke emission of esterified rapeseed oil was reduced remarkably by approximately 44.5% at 1500 rpm, full load in comparison with the commercial diesel fuel. The power, torque and brake specific energy consumption of the diesel engine showed very slight differences. It was concluded that esterified rapeseed oil could be utilized effectively as an alternative and renewable fuel for agricultural direct injection diesel engines.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.3
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• pp.49-57
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• 1991

Natural gas is one of the most promising alternative fuels for automative vehicles, because it has lower exhaust emissions and better fuel economy characteristics than gasoline and can be used in conventional engines with a little modification. In the present study, a conventional gasoline engine was modified to a CNG dedicated engine, which can be operated with CNG( compressed natural gas) only, and a engine bench test was performed at various compression ratios. As a result, it was revealed that the prototype CNG engine can be operated with lower exhaust emissions, better fuel economy and better thermal efficiency, but with a sightly reduced brake horse power, compared to the conventional gasoline engine.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.396-403
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• 2016

Usually, large-sized buses and trucks have a very high load. In addition, frequent braking during downhill or long-distance driving, causes the conventional method using the brake friction to have a problem in safety because of brake fade and brake burst phenomenon. Auxiliary brakes dividing the braking load is essential. Hence, environment-friendly auxiliary brakes, such as contactless brake rather than the engine auxiliary brake system are needed. A study aimed at improving the energy efficiency by recharging electric energy with changing mechanical to electrical energy that occurs when braking is actively in progress. In this paper, the voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, the resonant L-C circuit is configured in the retarder. The voltage generated in the retarder is simply modeled as a transformer. However, retarder voltage control in this paper is simulated by modeling the induction generator because this induction generator modeling is more practical than transformer modeling. The changes in the voltage of the resonance circuit, which depends on the switch pulse duration of the control device, were analyzed. A PI controller algorithm to control this voltage is proposed. The feasibility of modeling retarder and voltage controller are shown by using MATLAB Simulink in this paper.

• Journal of Mechanical Science and Technology
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• v.18 no.1
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• pp.30-36
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• 2004

In this paper, operation algorithms for a parallel HEV equipped with a relatively small motor are investigated. For the HEV, the power assist and the equivalent fuel algorithms are proposed. In the power assist algorithm, an electric motor is used to assist the engine which provides the primary power source. Tn the equivalent fuel algorithm, the electric energy stored in the battery is considered to be an equivalent fuel, and an equivalent brake specific fuel consumption for the electric energy is proposed. From the equivalent fuel algorithm, distribution of the engine power and the motor power is determined to minimize the fuel consumption for a given battery state of charge (SOC) and a required vehicle power. It is found from the simulation results that the fuel economy and the final battery SOC depend on the motor discharge energy and it is the best way to charge the battery only by the regenerative braking, not by the engine to improve the overall fuel efficiency of the HEV with the relatively small motor.

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.92-97
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• 2017

Kerosene (Coal oil) is a particularly attractive fuel because it is widely used to power jet engines of aircraft as jet fuel and some rocket engine. This paper describes the performance and emission characteristics according to the collant temperature of combustion chamber head of spark ignition engine fuelled with kerosene. As a result, the following knowledge is obtained. As the collant temperature of combustion chamber head is decreased, torque, volumetric efficiency and brake specific fuel consumption have been increased. When coolant temperature of combustion chamber lower, THC emission increased but CO and $NO_x$ emission decreased.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.545-550
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• 2004

The deterioration of a shunting locomotive was characterized for the lifetime assessment. The locomotive has been used for shunting works in steel making processes, and in this investigation, various types of technical evaluation methods for the locomotive parts were employed to assess the current deterioration status and to provide important clue for lifetime prediction. Unlike other rolling stocks in railway applications, the diesel shunting locomotive is composed of major components such as diesel engine, transmission, gear box, brake system, electronic devices, etc. In this paper, the degree of deterioration in a diesel engine and power transmission parts has been presented based on the analysis results.