• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.64-75
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• 1991

The design of structures of modern industry has developed to satisfy stringent service, realiability and safety. Up to now, geometric profile which means surface foughness and dimension accuracy is mainly treated in manufacturing process of work surface. But it is inevitable to evaluate changes of surface geometry as well as the nature of alterations in surface layers because surface of workpiece changes as a result of phase transformation, chemical changes, plastic deformation and stress changes. This paper is to present principal data for safety design by verifying the effect of grinding conditions and method in grinding layers and to explain the method of measuring surface integrity. In this paper, structural steel(SM20C) is used as a workpiece. Of integrity, surface roughness in view of surface texture is analyzed by frequency domain and residual stress, structures and defect of ground layers in view of surface metallurgy are investigated.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.44-53
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• 1994

We experimented on cutting characteristics-cutting force, behavior of cutting temprature, surface foughness, behavior of chips-under low tempdeature, which generated by liquid nitrogen (77K). The workpieces were freezed to -195 .deg. C and liquid nitrogen was also sprinkled on cutting area in order to increase the efficiency of machining in low temperature. The workpiece was became to -195 .deg. C in 5 minutes, and cutting temperature in CC was lower about 170 .deg. C than NC. The cutting force trended to increase slighty in cooled cutting, but chip thickness was decreased, shear angle was however increased. The form of chips was in good conditions of long or short tubular chips in CC. In CC surface roughness of workpiece was better than NC. In NC surface hardness of chips trended to increase according to increasing of cutting speed, but in CC it trended to decrease. The power spectrum of vertical cutting force trended to increase according to increasing of feed, and in CC it was higher than NC.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.4
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• pp.175-183
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• 2002

In this paper, the surface modification effect of self-assembled monolayer(SAM) of 1-dodecanethiol [$CH_3$($CH_2$)$_{11}$SH] used as an anti-adhesive film in micromolding process was studied. Monolayers of 1-dodecanethiol[$CH_3$(CH$_2$)$_{11}$SH] were obtained by immersing a metal place in pure 1-dodecanethiol. SAM film on the nickel plate has been examined by using X-ray photoelectron spectroscopy(XPS). The focus has been placed on S-Ni bonding. From the XPS analysis, sulfur atoms were detected from the SAM film as a chemical composition of S-Ni. In order to measure an adhesion force of the SAM-coated nickel surface, atomic force microscopy(AFM) was used in force-distance mode, which whows the micro-adhesive force on solid surface. It was shown that adhesion forces measured from the SAM-coated nickel surface and the Ni surface without SAM coating were 3.52nN and 5.32nN, respectively. In order to investigate the effect of SAM coating on the surface foughness the replica in demolding process, hot embossing experiments were performed using a SAM-coated nickel master and a nickel master without SAM coating. Surface roughness of replica from the SAM-coated master showed 25nm and that of replica from master without SAM coating was 35nm. The smoother surface roughness of the replica from the SAM-coated, master is believed to result from reduction in the adhesion forces.ces.

• Journal of the Korean Society for Precision Engineering
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• v.3 no.1
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• pp.69-76
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• 1986

The measuring Method by stylus, which measures surface roughness, has been widely used since G. Schmaltz developed the first equipment of that type. Withe the resent development of the measuring method by stylus, surface foughness testing instruments of the very high magnification ratio, hundreds of thousands, are manu- factured. However, as the techniques of the high precision roughness measurement are being required, the response problems due to the tip shapes and the plastic deformations of measured surface of mild material are to be serious factors. In this study, diamond stylus of tip radius $0.5\mu\textrm{m}$, $2\mu\textrm{m}$, $5\mu\textrm{m}$ and $10\mu\textrm{m}$ were used under the measuring force of 0.01gf, 0.02gf, 0.07gf, 0.4gf and 1.6gf, and from the experimental data, maximum measured value devrements between $2\mu\textrm{mR}$ stylus and $5\mu\textrm{mR}$ stylus, $2\mu\textrm{mR}$ stylus and $10\mu\textrm{mR}$ stylus are 22% and 31%, respectively when the measured value of $2\mu\textrm{mR}$ stylus goes to $0.01\mu\textrm{m Ra}$, $\lambda$ c2.5mm. And it is shown that plastic deformations on the plastic deformations on the measured surface are proportional to W/R(W;measured force, R;stylus tip radius).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.2
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• pp.107-115
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• 1999

In order to develop a convenient method for the estimation of transport distance of settling stones in quiescent water or flowing water, introduced was the simple but relatively accurate equation of drag coefficient. The equation of drag coefficient introduced was confirmed to give relatively accurate evaluation for the drag force of smooth-surface sphere, and the effects of surface roughness and shape can be considered by adjusting empirical parameters. A theoretical equation has been developed for the settling velocity or settling distance of smooth-surface sphere in quiescent fluid, and the computation results have been obtained by adjusting the empirical parameter for the settling distance of stone in quiescent water. The 2nd order ordinary differential equation has been developed for the case of settling stones in flowing fluid, and a numerical model has been developed by using Runge-Kutta method for its solution. A number of cases have been tested by adjusting the empirical parameter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.39-43
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• 1996

This paper described on the effect of residual stocks in internal grinding of tungsten carbide materials in order to improve the grinding efficiency as well as grinding accuracy. Though the fundamental investigation is carried out for tungsten carbide materials using electroplated diamond wheel, the residual stock after grinding process is effective to the grinding effciiency. The obtained results are as follows: (1) Under the depth of cut(t) is constant and decreasing the workpiece velocity(Vw), the resiudal stock after grinding is increased, but the difference is little less than the difference by table speed. (2) Increasing the wheel velocity, the residual stock after grinding is decreased. Therefore in order to minimize the residual stock, the wheel velocity should be increased as far as possible. (3) The surface foughness and out-of roundness increased with depth of cut and table speed, and decreased with wheel velocity, but it may as well adopt as much as polssible under the dimensional tolerance which is required for high efficiency grinding. (4) In order to remove residual stock, the spark-out grinding shoule be done, and it also can be improved about 20 .approx. 25% throughout spark-out grinding, and the number of optimal spark-out times were within 10 times.