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[論文] 실린더 내부 유동장에 대한 흡입 밸브의 편심 효과에 관한 수치적 연구
양희천(H.C.Yang),최영기(Y.K.Choi),유홍선(H.S.Ryou),고상근(S.K.Kauh),허선무(S.M.Huh) 한국자동차공학회 1992 오토저널 Vol.14 No.4
Three dimensional numerical calculation carried out to investigate the eccentricity effect of intake valve on the in-cylinder flow fields for the intake stroke and the compression stroke.<br/> During the intake stroke, a corner vortex in the vicinity of the valve exit interacted strongly with a toroidal vortex in the case of axisymmetric valve. But a weak interaction between the corner vortex and the toroidal vortex occurred due to the eccentricity of the valve in the narrow region between valve and cylinder wall in the case of offset valve.<br/> During the compression stroke, it was found that a solid body rotation was maintained in the radial-circumferential plane in the case of axisymmetric valve. But a weak secondary vortex was formed in the radial-circumferential plane in the case of offset valve, because of the interaction between swirl flows and inward flows towards cylinder axis.<br/> The calculated turbulence intensity presented a similar trend with the experiental results but, in spite of using the modified k-ε model, it was found that the qualitative difference between the numerical results and experimental results was large in the region where the velocity gradient is substantial.
온도변화가 실린더 주위 열전달계수에 미치는 영향에 관한 실험적 연구
고상근,Kauh, S.K. 대한설비공학회 1992 설비공학 논문집 Vol.4 No.2
coefficient precisely, experiments were carried out in three categories which contain the regime of (1) constant wire temperature (2) constant fluid temperature (3) constant temperature difference between wire and fluid. Measurements were made with electrically heated circular tungsten wire placed normal to air stream at the exit of jet. Heat transfer coefficient was increased with wire temperature increasing and decreased by fluid temperaure increasing and was not changed with varying both temperature if their difference were kept constant.
[論文] 비례적분 방식의 피드백 공연비 콘트롤 시스템 해석
이대영(D.Y.Lee),박경석(K.S.Park),고상근(S.K.Kauh),노승탁(S.T.Ro),김응서(E.S.Kim) 한국자동차공학회 1991 오토저널 Vol.13 No.5
Air/fuel ratio control system for gasoline engines has been analyzed to determine the control gain of the system. In this analysis the engine is modelled to be a simple time delaying element and the ramp-and-jump method is used to control air/fuel ratio. The result shows that it is necessary to measure the air flow rate accurately to enhance the control performance. And also it is shown that the control gain must be determined in some bounded region to meet the fast dynamic response and high catalyst conversion efficiency together.
유속에 따른 열선의 과열비 조정을 통한 열선유속계의 감도향상에 관한 연구
이신표,고상근,Kauh, S. K. 대한기계학회 1995 대한기계학회논문집 Vol.19 No.10
In this study, a new hot-wire anemometer which has greater sensitivity than that of a constant temperature anemometer (CTA) was proposed. In contrast to CTA, the wire working resistance of the new anemometer increases with flow velocity, that is, the operating mode of the wire becomes variable temperature. The variable temperature anemometer(VTA) was made by substituting a voltage controlled variable resistor such as photoconductive cell or transistor for one of the resistors in the bridge. By positively feeding back the bridge top signal to the input side of these electronic components, the wire overheat ratio could be increased with velocity automatically. Static response analyses of the VTA, constant voltage anemometer (CVA) and CTA were made in detail and calibration experiments were performed to validate the proposed operating principle. The wire operating resistance of the CVA decreases with velocity and this leads to lower sensitivity than that of a CTA. But the sensitivity of the newly proposed VTA is superior to that of a CTA, since the wire overheat ratio increases with velocity. Consequently, it is found that the major factor that is responsible for large sensitivity of a VTA is not the working resistance itself but the change of the wire working resistance with velocity.
[論文] 노크센서를 이용한 점화시기 피이드백 제어에 관한 연구
김연준(Y.J.Kim),고상근(S.K.Kauh) 한국자동차공학회 1992 오토저널 Vol.14 No.4
The ignition timing feedback control system was studied to enhance the engine power and to reduce the fuel consumption by optimizing the spark timing.<br/> The signal of a piezo-electric vibration transducer attached to the engine block was compared with that of a pressure transducer in order to determine the knock intensity. With the result of comparison the ignition timing feedback control system which detect the knock and correct the spark timing was set up.<br/> The ignition timing could be more advaced with this control system than with the existing system without the continuous knocking, therefore the engine torque was increased.