• 해양환경안전학회지
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• 제25권1호
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• pp.117-121
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• 2019

본 연구에서는 국내외적으로 환경문제 및 에너지절감의 일환으로 직류배전시스템을 선박에 적용하려는 연구 및 실증이 활발히 수행되고 있으며, 발전기를 직류배전시스템에 적용하기 위해서는 가변속 엔진을 적용하여 저부하 영역에서 발전기의 엔진 회전수를 줄여 연료소모량을 절감할 수 있는 방안이 제시되고 있다. 본 논문에서는 기존의 디젤발전기를 이용하여 발전기 컨트롤러, 가버너, AVR을 이용하여 직류배전용 가변속발전기를 구성하였으며, 발전기의 시스템 구성 방법, 가변속 발전에 따른 전력품질 시험(전압 및 주파수 변동특성, 부하변동 특성)을 통해 가변속 발전기의 전력특성을 분석 하였다. 가변속 발전기의 전압(250 ~ 440 VAC) 및 주파수(34 ~ 60 Hz)는 정격의 60 ~ 100 %로 구성하였으며, 엔진은 1100 ~ 1800 rpm 범위에서 운전되도록 설정 하였다. 부하변동에 따라 발전기의 엔진속도를 변경시켜서 발전기 출력의 전압, 전류, 주파수가 전력량에 따라 안정적으로 변동되는 것을 확인하였다.

• 오토저널
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• 제8권3호
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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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• 제16권7호
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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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• 제22권2호
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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.

• 대한기계학회논문집
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• 제11권5호
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• pp.725-730
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• 1987

본 연구에서는 2사이클 기관의 흡입 포오트 부근의 가스 유동을 레이저 도플 러 유속계를 이용하여 측정하고 가스의 평균 속도, 속도 변동, 유속 벡터 등을 기관의 회전 속도, 실린더 헤드의 모양 및 실린더로의 흡입 속도 측정점의 위치 변화에 대하 여 비교 검토하고, 유동 특성을 고찰하였다.

• 한국분무공학회지
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• 제14권1호
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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.

• 에너지공학
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• 제17권4호
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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.

• 대한기계학회논문집B
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• 제31권2호
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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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• 제33권2호
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• pp.218-231
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• 2008

본 실험 연구의 목적은 교사교육기관에서 예비 교사들에게 수송기술분야에서 엔진의 기본적인 인자들에 관한 개념 이해를 돕는 데에 있다. 실험엔진으로서 P8250을 사용하여 회전속도를 30~55 rps 범위 내에서 내연기관의 성능의 지배인자인 토크, 제동마력, 연료소비량 등의 기존자료를 구하였고, 이들을 바탕으로 기관의 제동마력과 토크선도로 구성되는 성능곡선을 만들었다. 이 연구에서 얻은 주요 결과를 정리하면 다음과 같다. 첫째, 엔진의 회전속도가 증가함에 따라서 동력 및 제동마력은 선형적으로 증가하고, 중속이상에서는 토크가 감소하였다. 둘째, 토크 및 비 연료 소모량의 변화를 확인할 수 있어 엔진성능의 개념을 이해할 수 있다. 셋째, 엔진성능의 제동마력과 토크의 실험값은 이론값과 유사한 경향을 보였다. 넷째, 회전속도에 따른 공연비는 엔진 회전수가 증가할수록 비례적으로 증가하였다.

• 오토저널
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• 제8권3호
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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.