• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.586-587
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• 2012

자동차 산업에 있어서 반도체 기술발전과 더불어 차량 내 기능들이 효율성, 경제성 및 친환경적인 관심을 고려하여 기계식 방식에서 전력전자식 방식으로 대체되고 있는 실정이다. 엔진의 연비를 향상시키기 위해서는 엔진의 연소효율을 개선하거나, 엔진에서 발생되는 손실을 줄이는 것이 필요한데, VVA(Variable Valve Actuation, 가변 밸브 작동) 기술은 엔진 흡기 유동 강화, 펌핑 손실 저감, 기계적 마찰 손실 저감등을 통해 엔진의 연비를 향상시킬 수 있다. 또한 VVA 엔진을 장착한 차량은 차량의 발진 응답성이 향상되고, 배기가스 배출량을 줄일 수 있어 친환경 저연비 차량을 실현하는데 핵심 차량부품기술이다. 최근까지 차량의 전동기 구동의 경우 DC모터 방식이 많이 적용되어 왔으나 DC모터의 내구성 및 효율 등의 이유로 BLDC모터로 바뀌고 있는 추세이다. 본 논문에서는 이와 같은 VVA 기구의 적용을 위하여 BLDC모터 제어기를 개발하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.686-686
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• 2013

Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. In addition to, there is a mechanical noise caused from movement of an actuator, electronically controlling a wastegate valve. It is called as valve rattle noise. The actuator is connected to a valve through a linkage. The noise occurs only if the valve is open, where the linkage is freely contact to neighbor structures without being constrained by any external forces. This condition allows impacts by the pulsation of exhaust gas, and the vibration from the impacts spreads out through turbine housing, causing the rattle noise. The noise is not in mechanical operating wastegate turbochargers because the linkage of an actuator is strongly connected by actuating force. For the electronic wastegate turbocharger, this paper proposed a test device to show the noise generating mechanism with a small vibration motor having an unbalanced shaft. It also shows how to reduce the noise - reduction of linkage clearances, inserting wave washers into a connection, and applying loose fitting in bushing embracing a valve lever to turbine housing.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.1-8
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• 2016

It was examined that start-up characteristics of a staged combustion cycle engine powerpack. Among various parameters, valve opening time was considered as a main factor affecting the start-up characteristics. Using monte-carlo method, characteristics variation was analyzed when the valve opening time deviates from the nominal value. As a result, the main fuel valve opening time and the start turbine ending time were significant associated with the startup characteristics. When separating main fuel valve opening time and start turbine stop time, main fuel valve opening time was an important factor. For stable operation, the main fuel valve opening time must be set one second before after driving the start turbine. Likewise, it was confirmed that the startup analysis can suggest an appropriate startup sequence for a stable startup.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.51-58
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• 2002

A simulation model has been developed to predict the performance of 5-valve gasoline engine by gas exchange process with combustion model. In this study, we simulated the intake flow characteristics and performance of 5-valve engine with entwine speed and we compared the 5-valve engine performance with that of 4-valve engine. As a result. the calculated value was in consistency with the measured value relatively. The performance of 5-valve engine was higher than that of 4-valve engine in high engine speed region.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.27-34
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• 1997

The effects of the intake and exhaust valve timing to improve the engine performance in a spark ignition 3-cylinder LPG engine with a closed loop fuel supply system were studied. The engine torque and power have been measured using the 75kW EC-dynamometer while adjusting the optimal fuel consumption ratio with a solen- oid driver. As the results from this experiment, when intake valve opening is $12^{\circ}$ BTDC, intake valve closing is $36^{\circ}$ ABDC, exhaust valve opening is $12^{\circ}$ ATDC, and exhaust valve closing is $36^{\circ}$ BBDC respectively, the best torque characteristics in low and high speeds for a gives engine were obtained. And also we could find that the torque characteristics in low speeds were affected by the timing of exhaust valve open. An increased valve overlap by the EVC delay was ineffectual to the torque characte- ristics improvement in high speeds.

• Journal of ILASS-Korea
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• v.22 no.1
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• pp.22-28
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• 2017

In this study, the effects of intake valve closing timing by using Cam-in-Cam system on combustion and emission characteristics for diesel engine were investigated under GT-POWER simulation environment. As a result, it was found that volumetric efficiency and effective compression ratio were decreased as the intake valve closing(IVC) timing is retarded due to its backflow effect. Also, we found that in-cylinder pressure, heat release rate and NOx emission were decreased as IVC timing was retarded. These show that the LIVC(late intake valve closing) can be effective to control AFR and mixing rate in diffusion combustion of diesel engine.

• Journal of IKEEE
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• v.17 no.1
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• pp.57-62
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• 2013

In this paper, we have implemented an overflow valve for EURO5 Type and the performance evaluation system based on IEEE802 protocol. On injecting a diesel oil into an engine, it is necessity for an overflow valve that can sustain an engine oil status in front of the engine. In order to evaluate the performance of overflow valve, we need the leak test system with IT. The leak test system checks the pressure, switching time and operating time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1055-1062
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• 2012

In this paper, the mathematical models and control algorithm of a thrust control valve were described as a precedent study on the design of thrust control algorithm for a liquid rocket engine (LRE). Numerical simulations were performed using a simplified simulation system of an LRE and the developed mathematical models were validated by comparison with the experimental results. Through these research, basic data were acquired for the development of a thrust control algorithm for a LRE.

• Korean Journal of Materials Research
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• v.8 no.1
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• pp.64-70
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• 1998

자동차의 엔진밸브 스프링으로 사용되는 Si-Cr 스프링강의 영구 변형 저항성과 내피로성이 우수한 고강도강을 개발하기 위하여 탄소함량을 증대시키고 Mo, V, W와 같은 합금원소를 기존의 SAE 9254 스프링강에 첨가하여 개발강을 제조했다. SEM및 EDX가 부착된 TEM을 이용하여 미세조직을 관찰했고, 크립시험 및 피로시험기를 이용하여 스프림의 영구 변형 저항성 및 스프링의 내피로성을 조사했다. 실험결과, 개발강은 피로 특성치는 기존강과 동등 수준이면서 인장강도가 기존강의 것보다 10%가 더높은 2100MPa 급의 고강도를 나타내었으며 또한 영구 변형 저항성도 현저하게 개선되었는데 이는 W, Mo의 첨가로 인해 템퍼링시에 세멘타이트의 성장이 억제되어서 세멘타이트의 석출물이 미세하게 되었기 때문이다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.62-65
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• 2009

This study for prediction of startup characteristics for 30 tonf liquid rocket engine TP-GG-CC coupled test was performed on the basis of the previous TP-GG test and prediction results. For determining the valve sequence the startup analysis was performed by the specified program for several main valve time and the adequate valve sequence for startup could be obtained.