• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.423-429
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• 2012

Miller cycle is considered as an effective means to meet the regulation on Tier II and to reduce $CO_2$ emission. For this cycle, the amount of intake air supplied should be enough increased. Therefore, the intake system with minimized resistance for air flow is under consideration. In this study, the flow coefficients of intake valves were measured in order to obtain the basic data for the cycle simulation and intake port design. The flow coefficients were measured using the steady-flow test rig. As a test result for the poppet valve used the marine engine with medium speed, the flow coefficients are increased to about 0.62 with the valve lift. In addition it is confirmed that the flow coefficients have the characteristic value irrelevant to the S/B ratio.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.124-130
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• 1999

Flow characteristics of a compressible gas flow through a rotating disc-type rotary valve are investigated experimentally under various conditions. It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stoke cycle engines decrease with increase in engine speed. Rotary valve is one means by which air may be made to flow inter-mittently through a pipe. In this paper an exhaust system simulator of engine was used to experi-mentally analyze the decrease in flow rate at high rotation speeds and to determine what variables other than rotational speed give rise to the observed behaviour. These variables have been included in an empirical equation which is representative of the measured flow characteristics.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.1-6
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• 2007

This paper provides the effects on the leakage characteristics of the surface roughness of a valve stem in LPG automotive. The valve stem seal is to stop an oil leakage through a sealing gap between a valve stem and a valve stem seal. The sealing performance of two components is related to a leak safety and a long life of a valve stem and a valve stem seal. The experimental results show that the optimal surface roughness of a valve stem is to recommend as $0.4{\sim}0.5{\mu}m$ in a centerline average roughness, Ra and a uniformly distributed profile of the roughness. Basically the smooth surface and uniform profiles of the roughness may reduce an oil leakage between a valve stem and a valve stem seal.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.237.1-237
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• 2001

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.876-878
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• 2016

본 연구에서는 자동차 및 기계부품의 제조공정에서 핵심부품인 밸브바디의 주물공정 후 생성된 버(burr)를 제거하기위한 초음파 디버링 장치를 개발하고자하였다. 초음파 디버링장치는 진동부와 제어부로 구성되고 디버링효과의 극대화를 위해 디버링 수에 포함된 용존가스의 제거가 매우 중요함에 따라 용존가스 제어기법을 적용한 초음파 디버링 장치를 개발하고 평가실험을 수행하였다. 본 연구에서는 초음파 디버링에서의 용존가스에 따른 디버링 성능을 평가하고 실제 시스템에 적용하기위한 산업적용 가능성 평가를 수행하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3869-3875
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• 2012

In this study, mathematical modeling and experimental analysis were executed in order to evaluate the valve dynamic characteristics when the hydraulic pressure applied. High pressure on the master cylinder effects on the valve dynamic characteristics have been analyzed. The pulsation pressure generated in hydraulic systems causes noise, vibration and odd effect to the system. To reduce the pulsation pressure, high frequency PWM control of 20KHz was attempted. Also, an analytic method is proposed for the resultant forces of electromagnetism and hydraulic pressure generated in the real vehicle electro stability program. Consequently, results of solenoid valve dynamic characteristics analysis derived in the study can be confirmed criteria for the optimal control of electronic stability program system.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.613-619
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• 2016

A pneumatic control valve performs a major role in controlling the flow of a system or the level of a key tank in many power plants, and its performance should be guaranteed during the plant's lifetime. Its operation starts by supplying air to the pneumatic actuator or by exhausting the air from the actuator. To control the valve position, the amount of air supply or exhaust is adjusted by a control loop where various accessaries are equipped. In this paper, air leakage in the air supply line, changes in the valve packing force, and false adjustments of zero and the span of the positioner are simulated and analyzed using a 2-in pneumatic valve with a position control loop including an I/P converter and positioner, where the valve position is controlled within ${\pm}2%$ of the control pressure at 67% opening position.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.65-70
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• 1996

엔진소음을 소음특성에 따라 분류하면 공력소음(Aerodynamic Noise), 연소소음(Combustion Noise), 기계적인 소음(Mechanical Noise)으로 나눌 수 있으며 소음원의 종류에 따라 분류하면 배기계소음(Exhaust System Noise)으로 나눌 수 있으며 소음원의 종류에 따라 분류하면 배기계소음(Exhaust System Noise), 흡기계소음(Intake System Noise), 냉각계소음(Cooling System Noise), 엔진표면소음(Engine System Noise)등으로 분류할 수 있다. 이러한 여러소음중 엔진 내부의 유동에 의한 흡배기계통으로의 소음방출은 자동차 실 내외 소음의 중요한 문제로 대두되는데, 이를 줄이기 위해 그 동안 소음기 등의 서브시스템의 형태와 그 위치조정에 관한 연구가 수행되어 왔다. 그러나 이것이 비용 또는 성능에 영향을 미치므로 본질적인 소음원을 규명해 내는 것이 필요하게 되었다. 흡배기계의 소음은 엔진의 흡입, 배기행 정시 피스톤의 운동에 의해 팽창 및 압축파 형태의 압력파(pressure wave)로 발생하게 되고, 밸브근방에서는 유동의 박리(separation)에 의해 발생하게 된다. 소음기 등의 서브시스템에서도 유동의 박리에 의해 발생하게 되며 특히 배기행정시 발생하는 압력파는 비선형영역에 있게된다. 흡기소음은 배기에 비해 그 크기가 작아서 그동안 등한시 되어왔으나 이것이 소비자의 불평요인으로 작용하므로써 이에 대한 연구도 활발히 수행되어야 한다. Bender, Bramer[1]는 흡배기계 소음의 외부 방사에 관하여 전반적으로 기술하였고 Sierens등[2]은 흡기계에서 1차원 MOC(Method of Characteristics)방법으로 비정상 유동해석을 하고 실험결과와 비교하였다. J.S.Lamancusa 등[3]은 흡기 소음원을 실험을 통해 예측하였고, 흡기소음도 비선형 거동을 보인다고 밝혔다. Yositaka Nishio 등[4]은 새로운 흡기실험장치를 고안하여 공명기(resonator)의 위치 변화에 의한 저소음 흡기계를 설계 초기단계에서부터 적용하려 하였다. 일반적으로 흡배기계의 복잡한 형상 때문에 대부분 실험을 통해 문제를 해결하려 하였고, 수치해석은 피스톤의 운동을 배제한 단순화한 흡배기계의 정상상태 유동해석이 주를 이루어왔다. Taghaui and Dupont 등[5]은 KIVA코드를 사용하여 흡기포트와 연소실 그리고 밸브의 움직임을 동시에 고려한 수치해석을 도입하였다. 하지만 이들이 밸브의 운동을 고려하기 위해 사용한 이동격자는 격자점은 시간에 따라 변화하지만 그 격자의 수가 일정하게 유지되어 있어서 밸브의 완전개폐를 해석할 수가 없다. 강희정[6]은 단일 실린더와 단일 배기밸브를 갖는 문제로 단순화하여 피스톤과 밸브의 움직임을 고려하므로써 배기행정 후 소음이 어떻게 전파해 나가는가를 연구하였다. 본 연구에서도 최소밸브간격과 최대밸브간격 사이에서만 계산이 가능하나 흡기의 경우는 밸브가 닫힐 때 생기는 압력파가 중요하므로 실린더와 밸브사이에 벽면조건을 주어 밸브의 개폐를 모사하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.703-707
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• 2007

The line pressure control system for an automotive transmission in which a bleed type variable force solenoid(VFS) is applied, has been constructed and experimentally investigated. The hydraulic circuit of the system includes a line pressure control valve, a reducing valve, an accumulator, various orifices and a VFS. Static and dynamic responses of the throttle and line pressure have been monitored and discussed for various test conditions.