• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.05a
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• pp.41-46
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• 1996

For a vertical type crankshaft-journal bearing system used in scroll compressor, nonlinear transient response analysis is applied includung nonlinear fluid film reaction forces of journal beatings. By a connected behavior analysis of crankshaft and orbiting scroll, the radial clearance of scroll wraps is calculated. Considering tangential leakage for this clearance, a coupled analysis model for leakage and dynamic behavior of the orbiting scroll is made, and analyzed by iterative calculation. By regarding clearances of main, sub bearing of crankshaft and orbiting scroll shaft bearing clearance as design parameters, the radial clearance of scroll wraps is analyzed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.51-58
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• 1997

An experimental study was performed to discover the tribological behaviors of pure tin and zinc coated 52100 bearing steel. Pure tin coatings ranging from 30 nm to 30,000 nm and pure zinc coatings ranging from 500 nm to 52,000 nm were produced by a thermal evaporation coating method. Experiments using a thrust ball bearing-typed rolling test-rig were performed for the investigations of the effect of coating thickness on the tribological rolling behavior. Results showed that the existence of optimum film thickness which revealed minimum rolling resistance was discovered for tin and zinc coating. The compatibility of coating matehal to iron showed no significant effect on the rolling resistance behavior. The hardness of coating material revealed significant influence to the rolling resistance behavior.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.265-271
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• 1998

High temperature wear behavior of plasma sprayed zirconia based coating sealing with zirconia sol were investigated for high temperature wear resistance application. The zirconia powders containing 2.5, 5.0, 7.5, 10.0 mol% of MoS$_2$, $Fe_2O_3$ for plasma spray were made by spray drying method. As-sprayed coating was sealed by zirconia-sol to fill up the pore and crack in coating. wear test were performed at temperature ranges from room temperature to 600$\circ$C. The microstructural changes of before and after sealing process were examined by SEM, XRD and EPMA. After sealing process, the porosity was decreased and micro-hardness was increased. The wear properties of coating after sealing process were improved by sealing of pores and cracks. The behavior of wear amount and coefficient of friction were same tendency to before sealing process.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.59-66
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• 2000

An experimental study on the effect of silver particles on the sliding behavior of bearing steels was performed by using a ball-on-disk tribometer. Tests were carried out in ambient air, dry and vacuum. Disks of AISI 52100 were silver-coaled by a thermal evaporation method, and the effects of silver particle transfer on friction were firstly analyzed. In order to understand further the mechanism of silver particles transfer and its effect on friction and wear, pre-compressed silver particles were artificially introduced into the friction interface and the results were compared to those of silver-coated specimens. Results showed that the introduced silver particles produced transfer layers and resulted in low friction. It also showed that this low friction is closely related to the characteristic behavior of transfer layers. Shakedown and rachetting occurred at the friction interface and affected the friction and wear.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1991.06a
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• pp.50-54
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• 1991

This paper shows the effect of axial profile on the elastohydrodnamic lubrication (EHL) behavior of axially profiled cylindrical roller. For two different type of profiles which have nearly similar elastostatic pressure distribution, the EHL results show large differences. Especially the difference in film shape is larger than that of pressure distribution. Therefore, the magnitude of the minimum film thickness should be a major criteria to design the axial profile of the roller and a new design procedure is presented which take into account the minimum film thickness as well as the pressure distribution.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06b
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• pp.28-37
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• 1995

To protect the ozone layer depeletion the CFC (chlorofluorocarbon). HCFC(hydrochlorofluorocarbon) refrigerants will be replaced with HFCs (hydro-fluorocarbon) as an alternative refrigerant. In recent years a good deal of effort has been made to develop new compressors which are compatible to the new referigent. This paper focused on developing accelerated screening test for predicting tribological characteristics of the rotary compressor in atmosphere of R407C as an alternative refrigerant with polyolester lubricant. Falex wear test machine with high pressure chamber has been used to simulate friction and wear behavior of the common contact geometries found in rotary compressors.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06b
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• pp.48-53
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• 1995

본 연구에서는 윤활유막의 접촉압력 거동문제를 다른 각도에서 유한요소기법으로 해석하고자 한다. 즉, 혼합기가 폭발하게 되면 피스톤과 실린더 사이의 윤활유막이 순간적으로 초고압을 받아서 윤활유막은 밀폐된 공간에서 마치 폴리머처럼 거동할 것이라고 가정할 수 있다. 이와 같은 현상은 극히 짧은 시간에 국부적으로 일어날 것으로 예상되며, 이러한 작동조건에서 피스톤 링의 접촉면 형상에 따른 피스톤 압축링-윤활유막 사이의 접촉압력 거동문제를 미시적일 측면에서 유한요소기법으로 피스톤의 동적문제를 해석하고자 한다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.19-23
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• 2000

Stiction is an undesirable phenomenon that can be encountered often in Micro-Electro Mechanical Systems (MEMS) applications, In order to minimize this effect, Self-Assembled Monolayers (SAM) are commonly used. In this work the frictional characteristics of SAM are investigated using both micro-tribotester and SPM. It was found that the performance of SAM is quite sensitive to coating condition. The experimental results show promise for SAM to be used in sliding applications of micro systems.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.107-110
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• 2002

In this paper the result of investigation of wear of proceeding bearing is presented. Different parameters as sliding speed, load, materials capacity etc, have influence on the Tribological behavior of proceeding bearing. The wear of proceeding bearings of various issues is determined and analyzed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.179-184
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• 2002

Adhesive contact characteristics of torus-shaped bumps, which are commonly used to reduce friction and stiction in hard disks, are analyzed to examine the applicability to the MEMS structure. The analysis is conducted with the finite element technique considering the adhesive force. Torus-shaped bumps of various rim and bump radii are analyzed. The jump-to-contact behavior, adhesion hysterisis, pull-off forces, contact region and pressure, and surface and subsurface stresses are presented and discussed. Analysis results in the absence of adhesive force are also presented to identify the effect of adhesive force.