• Tribology and Lubricants
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• v.20 no.6
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• pp.337-342
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• 2004

One of the serious challenges in developing rotary compressor with HFC refrigerant is the prediction of scuffing times and wear amounts between vane and roller surfaces. In this study, the tribological characteristics of sliding surfaces using vane-roller geometry of rotary compressor were investigated. The sliding tests were carried out under various sliding speeds, normal loads and surface roughness. During the test, friction force, wear depth, time to failure and surface temperature were monitored. Because severe wear occurred on vane surface, TiN coating was applied on sliding surfaces to prolong the wear life of vane-roller interfaces. From the sliding test it was found that there was the optimum initial surface roughness to break in and to prolong the wear life of sliding surfaces. Depending on the load and speed, the protective layers, which were composed of metallic oxide and organic compound, were formed on sliding surfaces. Those would play an important role in the amounts of friction and wear between roller and vane surfaces.

• Bulletin of the Korean Mathematical Society
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• v.35 no.3
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• pp.547-557
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• 1998

In this paper, we study submanifolds in the Euclidean space with parallel normal mean curvature vectorand special quadric representation. Especially we give a complete classification result relative to surfaces satisfying these conditions.

• Tribology and Lubricants
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• v.19 no.2
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• pp.109-115
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• 2003

Nanotribological characteristics between a Si$_3$N$_4$ AFM tip and hydrophobic thin films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM (atomic force microscope) and LFM (lateral force microscope) modes in various .ranges of normal load. Plasma-modified thin polymeric films were deposited on Si-wafer (100). Results showed that wetting angle of plasma-modified thin polymeric film increased with the treating time, which resulted in the hydrophobic surface and the decrease of adhesion and friction. Nanotribological characteristics of these surfaces were compared with those of other hydrophobic surfaces, such as DLC, OTS and IBAD-Ag coated surfaces. Those of OTS coated surface were superior to those of others, though wetting angle of plasma-modified thin polymeric film is higher.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.3
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• pp.60-67
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• 1999

The CLSM and the image analysis technique enhanced observation of fiber wall fibrillation occurred in both the outer and the fiber wall surfaces during refining by non-destructive techniques. In the early stages of refining, it was well observed that a partial separation between the S1 and S2 layer in the secondary wall was made generating a space in the wet fiber walls . With further refining, it was clearly shown that the shear forces imparted by the refiner bar surfaces caused the S1 layer to become totally separated from the S2 layer as well as creating microfibrils. Furthermore, the fibrillation in the inner fiber wall surfaces could be due to the normal force (Fn) by refiner bars, friction force between a fiber and refiner bars (Fs) and inner friction force between fiber walls(fs). It was confirmed that the concept of fibrillation should be extended to fibrillation in the inner fiber wall surfaces as well as internal and external fribrillation.

• Bulletin of the Korean Mathematical Society
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• v.54 no.1
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• pp.159-175
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• 2017

We solve the $Bj{\ddot{o}}rling$ problem for constant mean curvature one surfaces in hyperbolic three-space and in de Sitter three-space. That is, we show that for any regular, analytic (and spacelike in the case of de Sitter three-space) curve ${\gamma}$ and an analytic (timelike in the case of de Sitter three-space) unit vector field N along and orthogonal to ${\gamma}$, there exists a unique (spacelike in the case of de Sitter three-space) surface of constant mean curvature 1 which contains ${\gamma}$ and the unit normal of which on ${\gamma}$ is N. Some of the consequences are the planar reflection principles, and a classification of rotationally invariant CMC 1 surfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.364-365
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• 2005

This paper report nanotribological behavior between Si tip and Cu wafer surfaces which was treated various concentration of $H_2O_2$. This experimental approach has proven atomic level insight into Cu CMP. It has been used to study interfacial friction and adhesion force between Si tip and Cu wafer surfaces in air by atomic force microscopy (AFM). Adhesion force of Cu surfaces which was pre-cleaned in diluted HF solution was lager than Cu oxide surfaces. Adhesion force of Cu oxide surface was saturated around 7 nN. Slope of normal force vs lateral signal was increased as increasing concentration of $H_2O_2$ and it was saturated around 24. Friction force of Cu oxide was lager than Cu.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.267-280
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• 1992

This paper describes a numerical analysis of the light scattering patterns of roughness profiles. This analysis was based upon the light scattering theory developed by Beckmann. In the analysis, the roughness profile was regarded as a profile whose irregularities depend on the production process and the shape of cutting tool. Generally, waviness of an actual surface seriously distorts the scattered pattern of roughness profile. In order to avoid the effects of waviness of actual surfaces, several theoretically calculated scattering patterns, instead of actual scattering patterns, were used to analyze the scattering patterns of typical engineering roughness profiles. The characteristics of the light scattering patterns for five model surfaces were studied.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.2
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• pp.197-202
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• 2001

The biomechanical analysis of the load carrying effect on different floor surfaces has been conducted. Four different floor surfaces were prepared for ten subjects with each walking at a fixed velocity(1.33 m/sec) while carrying five different loads. The results showed that because of the significant interaction effect between floor slipperiness and the load carrying task, the load carrying effect should be analyzed according to different levels of the floor slipperiness, especially contaminant floors. On oily surfaces, slip distance(SD) and heel velocity (HV) increased whereas stride length(SL) decreased as load increased. In other words, significantly longer SD, faster HV, and no normal gait were found as load increased. As a result, a different protocol should be applied to measure floor slipperiness on oily floors as compared to dry surfaces for tribological approach.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.89-95
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• 1995

The adsorption of methanethiol and benzenethiol on Ag(111) and Ag(100) surfaces is studied respectively, employing ASED (Atom Superposition and Electron Delocalization) method. Metal surfaces are modelled by 3-layer clusters. The corresponding thiolate anions are taken as adsorbates. The highly coordinated binding sites are most favored for both surfaces. The tilted angles of C-S axis from the surface normal are nearly zero. There's Charge transfer from adsorbate to substrate and the stretching frequency of C-S bond upon adsorption is blue-shifted from its gas phase counterpart, and its amount is the smallest at most highly coordinated site. FMO (Fragment Molecular Orbital) analysis of the system give the explanation for these results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.227-228
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• 2002

One of the serious challenges in developing rotary compressor with HFC refrigerant is the prediction of scuffing times and wear amounts between vane and roller surface. In this study, the tribological characteristics of sliding surfaces using roller-vane geometry of rotary compressor were investigated. The sliding tests were carried out under various sliding speeds, normal loads and surface roughness. During the tests, friction force, wear scar width, time to failure, surface temperature, and surface roughness were monitored. Because severe wear was occurred on vane surface, TiN coating was applied on sliding surfaces to prolong the wear-life of vane-roller interfaces. From the sliding tests, it was found that there was the optimum initial surface roughness to break in and to prolong the wear life of sliding surfaces. Depending on load and speed, the protective layers, which were composed of metallic oxide and organic compound, were formed on sliding surfaces. Those would play an important role in the amount of friction and wear between roller and vane surfaces.