• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.1
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• pp.117-121
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• 2019

In this study, research and a demonstration for applying DC distribution systems to ships as an environmental and energy conservation solution in domestic and foreign countries were actively carried out. In order to apply a generator to a DC distribution system, a variable speed engine was used. Both engine speed and fuel consumption were reduced. In this paper, a DC generator for DC distribution was constructed using a diesel generator, a generator controller, a governor, and an AVR. A system configuration method for a generator, power quality test, and the power characteristics of a variable speed generator were analyzed. The voltage (250 - 440 VAC) and frequency (34 - 60 Hz) of the variable speed generator were set to 60 - 100 % of the rated value, and the engine was set to operate from 1100 - 1800 rpm. It was confirmed that the voltage, current, and frequency of the generator output fluctuated in a stable manner according to the power amount when changing the engine speed of the generator according to the load variation.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.3
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• pp.16-27
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• 1986

In this study, low emission gasoline engine system is developed utilizing an EGR valve, 3 way catalytic converter and electronic fuel injection system. EGR was controlled by a needle valve and optimized at the engine conditions. Throttle body fuel injection system is used for fueling. When the engine was operated at constant speed by the electronic engine control system with the 3 way catalytic converter, th emissions were reduced by 50 to 90% in volume depending on he engine operating conditions.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.882-888
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• 2002

In this paper, an algorithm to increase the shift speed is suggested by increasing the line pressure for a metal belt CVT. In order to control the shift speed, an algorithm to calculate the target shift speed is presented from the modified CVT shift dynamics. In applying the shift speed control algorithm, a criterion is proposed to prevent the excessive hydraulic loss due to the increased line pressure. Simulations are performed based on the dynamic models of the hydraulic control valves, powertrain and the vehicle. It is found from the simulation results that performance of the engine operation can be improved by the faster shift speed, which results in the improved fuel economy by 2% compared with that of the conventional electronic control CVT in spite of the increased hydraulic loss due to the increased line pressure.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.225-231
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• 1998

Flame propagation speed characteristics of methante-air mixtures were experimentally investigated in combustion chamber modelled engine. Flame propagation process was known as a funtion of equivalence ratio initial pressure and initial temperature. Ion probe and schlieren photograph were applied to measure the local flame speed and flame radius in quiescent mixtures. Pressure was also measured to make sure of the reproducibility and to apply combustion analysis. Burning velocity was calculated from the flame propagation speed and combustion analysis. Flames were developed faster with higher initial pressure and initial temperature but showed maximum propagation speed at equivalence ratio 1.1 regardless of initial pressure and temperature. Local flame speed was maximum values at near midpoint between center and wall.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.725-730
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• 1987

An experimental study of the air flow through inlet pipe of reciprocating two-cycle engine was investigated under motored condition. Measurements of the two components of velocity, velocity fluctuation, and the other behavior of inlet flow have been obtained by laser Doppler anemometer system. The research engine comprised the cylinder head of a two-cycle engine which mounted on optical spacer with measuring window and glass inlet entry for laser anemometer measurement. A dual beam laser Doppler anemometer was used with conventional forward scattered method and comprised argon-ion laser, frequency shifter with Bragg cell module, and the signal processor. Measurements of mean velocity fluctuation of inlet flow for different engine speeds, measuring positions, and the changes in cylinder volume are investigated. The results presented show that the changes in engine speed is shown to be strongly influenced on the mean velocity of inlet air. The effect of measuring position and cylinder volume on the inlet velocity was also investigated for the inlet port entry and is shown to be small compared to the engine speed.

• Journal of ILASS-Korea
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• v.14 no.1
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• pp.34-38
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• 2009

This paper presents the pulsation of carburetor inlet and outlet pressure of a small SI gasoline engine. The engine used in this paper is a 23cc, single cylinder, diaphragm carburetor, two-stroke, air-cooled for brush cutter. The rpm and pressure wave pulsation at the inlet and the outlet of carburetor were measured and analysed for the understand of the internal air flow into the barrel on the diaphragm carburetor. These data should be used for the development of the duel fuel injection system for gasoline and LPG. The results showed that the carburetor inlet pressure variations were very steady, but the pressure variations at carburetor outlet were very sensitive to the pressure variation into the crank case and were to similar independently to the engine speed on partial opened throttle conditions. According to increasing engine speed, the pressure waves started to come out and be developed after closing the intake port of the engine at carburetor outlet. Reverse flow occurred on the WOT (wide open throttle) condition.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.198-203
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• 2008

The objective of the research was to study the effects of Miller cycle in a modified using diesel engine. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. The results of engine performances and emissions are present in form of graphs. Miller Cycle without supercharging can increase brake thermal efficiency and reduce brake specific fuel consumption. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency. Retard ignition timing can reduce $NO_x$ emissions while maintaining high efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.132-140
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• 2007

The temperature and soot of the visualized diesel engine's turbulent flow of the flame was measured qualitatively. In the combustion chamber, in order to judge the affect that the swirl current has on the current ratio two heads with different ratios were used. Using a high speed camera, the results were analyzed using flame visualization. In order to measure the temperature and soot of the turbulent flames like diesel flames, two color methods were used to acquire temperature and the soot of the flames according to the conditions through analyzing the two wavelengths of the flames. It was possible to measure the highest temperature of the non-swirl head visualized engine, which is approximately 2400K, and that swirl head engine managed up to 2100K. With respect to the visualized diesel engine soot, we got the grasp of the KL factor which bears the qualitative information of the soot. This study is dedicated to suggesting the possibility of measuring not only the temperature but also soot of the diffusion flame of the diesel engine turbulent flames.

• 대한공업교육학회지
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• v.33 no.2
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• pp.218-231
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• 2008

The purpose of this study was made for the pre-teacher of university to enhance understanding for the concept of engine performance and to provide information regarding engine performance in the institute of teacher educator. This study was carried out through engine performance experiment with The Cussons Engine Test Bed P8250, internal combustion engine, in order to analyze data quantitatively, and apply and verify factors of controlling engine performance. The main results of this study are as follows: First, power and brake horsepower increased linearly, and torque over the mid-speed as engine rps(revolution per second) decreased. Second, the change of torque and specific fuel consumption were able to be verified and the concept of engine performance was able to be understood. Third, the experimental values of brake horsepower and torque on engine performance showed the same tendency as theoretical values. Fourth, air/fuel ratio increased proportionally as engine speed increased.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.3
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• pp.46-54
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• 1986

Driving pattern of gasoline passenger car was measured and analyzed at some areas(6urban area routes, 4 radial routes, 4 circular routes)in Seoul city. Measured items were vehicle speed, engine speed, intake manifold vacuum, and fuel consumption. Driving pattern data were reappearanced with engine dynamometer. Results of this investigation might be summarized as below; 1. When we compared urban area route with radial or circular route in rush hour, it was found that the average vehicle speed was measured to be lower about 25% and fuel consumption to be higher about 12% in urban area route. 2. Average vehicle speed was measured to be higher about 30% and driving resistance output to be higher about 25% in non-rush hour, but average fuel economy was increased a little. 3. On the bases of average fuel economy and characteristics of exhaust emissions, optimum driving vehicle speed was found about 60 km/h in the 4th(top)and about 40km/h in the 3rd in driving of experimental engine. 4. Idling frequency and exhaust emissions of CO,HC were related to idling closely. But exhaust emission of NOx, which had nothing to do with idling frequency, had relation to acceleration time ratio.