• Journal of the Korean Graphic Arts Communication Society
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• v.24 no.2
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• pp.61-68
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• 2006

Rubber rollers in off-set printing process are one of the most important factor, transferring the ink and water to the plate. Each different roughness of roller surface and different rubber compounds could effect to ink transparency and printability. Three different rubber compounds (NBR, EPDM, PU) and each different roughness of roller surface would show us different result of ink transparency and density of actual printing result. There might be a differences from actual printing result not only the amount of transferred ink, but there is also some other point we should check it out. According to the result of this studies, we found that different rubber compounds and their surface roughness directly effect to the rate of ink transfer. It also shows that the amount of transferred ink is not even and stable amount what we expect to get optimum printability. To reach a targeted printability with rollers, firstly it is necessary to choose correct rubber compounds with certain purpose and the roughness of roller surface has to be as smooth as less than $5{\mu}m{\sim}7{\mu}m$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.321-336
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• 2012

The shear behavior at the particle/surface interface such as rock joint can determine the mechanical behavior of whole structure. Therefore, a fundamental understanding of the mechanisms governing its behavior and accurately estimation of the interface strength is essential. In this paper, PFC, a numerical analysis program of discrete element method was used to investigate the effects of the surface roughness crushing on interface strength. The surface roughness was characterized by smooth, intermediate, and rough surface, respectively. Particle shape was classified into one ball model of circular shape and 3 ball model of triangular shape. The surface shape was modelled by wall model of non-crushing surface and ball model of crushing surface. The results showed that as the bonding strength of ball model decreases, lower interface strength is induced. After the surface roughness crushing was occurred, the interface strength tended to converge and higher bonding strength induced lower surface roughness crushing. Higher friction angle was induced in wall model and higher surface roughness induced the higher friction angle. From these findings, it is verified that the surface roughness and surface roughness crushing effect on the particle/surface interface shear behavior.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.23-33
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• 2020

In this study, the effect of surface roughness distribution and its influence on the inflight icing code was investigated. Previous numerical studies focused on the magnitude of surface roughness, and the effects were only addressed in terms of changes in thermal boundary layers with fully turbulent assumption. In addition, the empirical formula was used to take account the turbulent transition due to surface roughness, which was regarded as reducing the accuracy of ice shape prediction. Therefore, in this study, the turbulent transition model based on the two-equation turbulence model was applied to consider the effects of surface roughness. In order to consider the effect of surface roughness, the transport equation for roughness amplification parameter was applied, and the surface roughness distribution model was implemented to consider the physical properties. For validation, the surface roughness, convective heat transfer coefficient, and ice shape were compared with experimental results and other numerical methodology. As a result, it was confirmed that the excessive prediction of the heat transfer coefficient at the leading edge and the ice horn shape at the bottom of the airfoil were improved accordingly.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.33-37
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• 1995

A side-cut grinding generates a machining error by the decrease of the quill rigidity. In this paper, The effect on the grinding force, machining error and surface roughness due to the change of the quill rigidity is investigated experimentally. The slenderness ratio of the quill is a significant factor to analyse the change of the grinding force and machining error.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1025-1028
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• 2001

In this report, a new method compounding the electrolytic machining with ball end milling process to increase the machining efficiency was introduced. From the experimental result, it was confirmed that effect of cutting force reduction and finer surface roughness can be obtained in a certain condition of ball end milling and electrolytic machining conditions.

• KSTLE International Journal
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• v.3 no.1
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• pp.7-11
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• 2002

The roughness effects are very important due to the presence of interacting asperities in mixed lubrication regime. An average Reynolds equation using flow factors is useful to determine the effects of surface roughness on mixed lubrication. In this study, the effect of kurtosis on flow factors is investigated using random rough surfaces generated numerically, The results show that flow factors are very sensitive to h/$\sigma$ according to the value of kurtosis in the partial lubrication regime.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.263-268
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• 1999

Langasite, a new piezoelectric material was polished by CMP(chemical mechanical polishing). To enhance the polishing rate, alumina abrasives were added to commercial ILD1300 slurry which contains silica abrasive. The effect of added alumina 0 the silica slurry on the polishing rate and damage of langasite was investigated, Experimental results show that the polishing rate and roughness increases with increasing added alumina particle size, Crystallinity of the langasite is also lowered by alumina addition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.497-502
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• 1998

To understand the effect of surface roughness on silicon wafer bonding, a continuum mechanical model is presented. This model is based on Obreimoff's experiment and the contact theory of rough surfaces. The surface energy of silicon was calculated to be much reduced than the theoretical value. Problems are discussed concerning surface film effects and the assumption of constant asperity radius and statistical distribution function.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.347-348
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.521-522
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• 2007