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자동변속기 주축의 회전에 따른 변속기유 분출량 측정 연구
장시열(Siyoul Jang),이덕재(Duckjae Lee),박준수(Junsu Park),김학수(Haksu Kim),이정선(Jeongseon Lee) 한국트라이볼로지학회 2007 한국트라이볼로지학회 학술대회 Vol.2007 No.6
The durability and efficiency of an automatic transmission are greatly affected by the lubrication properties of transmission fluid. However, it is difficult to exactly estimate the flow rate of lubricating oil at each part of automatic transmission because of its structural complexity under the rotating condition. This study is performed on oil flow distribution measures though each oil hole inside the main shaft supplying ATF for system parts. Oil enters a horizontal tube through entry and discharges into open air via radially-attached branches. Oil flow, pressure and rotational speed are varied. Changes in flow rate with rotational speed are obtained. This study is believed to be the start for the optimal design of the lubricating system in the automatic transmission.
비정상 상태의 선접촉 탄성유체윤활 유막두께 및 유막압력 특성연구
장시열(Siyoul Jang),조재철(Jae Cheol Cho) 한국트라이볼로지학회 2009 한국윤활학회지(윤활학회지) Vol.25 No.5
Elastohydrodynamic lubrication (EHL) analysis shows that film thickness is very flat in the contact area and pressure distribution is somehow similar to that of Hertz ian contact pressure except the outlet region with pressure spike. These typical patterns of EHL film thickness and pressure are the cases under the steady contact conditions of applied loads and speeds. However, many engineering contacts are rather under the conditions of varying loads and contact speeds, and therefore the predictions for endurance life and performance of machine elements with steady EHL analysis are not suitable in many occasions. This study shows the differences in film thickness formation and pressure distribution between steady and transient contact conditions in several contact cases.
고온 고전단 변형률 속도 조건에서 멀티그레이드 윤활유의 유막두께 형성 측정 연구
장시열(Siyoul Jang),김재홍(Jaehong Kim),배대윤(D. Y. Bae),유성춘(S. C. Yoo),이병옥(B. Rhee) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.11
It is important to decide the minimum film thickness and viscosity of a multigrade lubricant in a contact surface between engine composition articles. By carrying out acceleration, deceleration, and sliding-rolling ratio movement, it is experimented that film formation variations in the contact surface are measured. In order to exactly investigate the variations of a multigrade lubricant film thicknesses. optical interference images are continuously taken by high resolution CCD camera, the friction torques in a contact surface measured simultaneously as well.
장시열(Siyoul Jang),박경근(Kyoung Kuhn Park),김완두(Wandoo Kim) 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-
Ball reducer with waved grooves has many advantages over other reducers for the high-reduction ratios, low noise and low energy loss, etc. The mechanism of force transmission is very similar to that of cam and follower in automobile valve train system especially in the contact geometry. In this study, we have investigated the traces of contact between ball and outer race and the working behaviors with a certain reduction ratio. In order to verify the contact behaviors between ball and outer race, which determines the critical endurance life the contact velocity and load are computed for a cycle. During some period of a cycle, the contact velocity reverses its direction very suddenly, which causes undesirable endurance performance of this machinery. From the computational investigation in this work, we hope to predict similar contact damages in other machinery due to this kind of contact behaviors, which is very common in many contact phenomena.
롤러 축방향 프로파일의 형태에 따른 캠-롤러 종동물 접촉 유막 압력 해석 연구
장시열(Siyoul Jang),김완두(Wandoo Kim),김민철(Minchul Kim) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.11
Roller contacts with the consideration of finite axial length are studied with the respect of elastohydrodynamic lubrication. The profile of the axial direction in rollers is the main design factor in order to increase fatigue life due to the stress concentration along the edge of the roller. Even under the ehl lubrication conditions, the stress concentration along the edge of the roller greatly influences the fatigue life both for the roller and contacting bodies. In this work, several profiles are investigated to verify how the ehl film and pressure are generated and which profile is recommendable for the ehl contact condition.
영상이미지 기법을 이용한 탄성유체윤활 접촉의 유막압력 계산연구
장시열(Siyoul Jang) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.6
Many EHL (elastohydrodynamic lubrication) experiments have been performed with the regard to film thickness variations according to contact conditions, such as load, sliding-rolling ratio, contact accelerations. The measured images of film thickness by interferometry system are easily converted into film thickness values even in nanometer scale and resolution. This image process technique makes it possible to convert the measured film thickness into contact pressures if the contact geometry and material properties are known. The computation of fluid film pressure from the image processing technique is compared with that of computational EHL film pressure to find other contact properties.
커넥팅로드-크랭크핀 질량 분포에 따른 엔진 베어링의 하중지지력 변화 연구
장시열(Siyoul Jang) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.36 No.-
Mass inertia effects on the journal traces in bearing clearance has been investigated for better mass distribution of crankshaft system components as well as better lubrication on the big-end bearing. In this preliminary study, crank pin traces in the clearance of engine bearing are studied by varying the sizes of pin mass, while most previous studies regarding journal locus with dynamic loading system have neglected the inertia effect of crank pin mass according to Jr film theory. Although the inertia effect of pin mass is negligibly small compared to viscous force in Jr film theory, it gives a great amount of influences on the journal traces in full bearing computation. In this work, we have found somehow influential effects on the load carrying capacity and some results are shown.