• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.388-392
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• 1995

The Electronic Speckle Pattern Interferometry(ESPI) has been applied to many technical problems such as deformation and displacement measurement, strain visualization and surface roughness monitoring. Composite materials have various complicated characteristics depending on the ply materials,ply orientations,ply stacking sequences and boundary conditions. Therefore, it is difficult to analyze composite material. For efficient use of composit materials in engineering applications, the dynamic behavior such as, natural frequencies and modal patterns should be identified. This studying presents FEM results for the free vibration of symmetrically laminated composite as [30/-30/90] $_{s}$. The natural frequencies of laminated composite rectangular plates having the boundary condition(:2-edge clamped) are experimentally obtained. In order to demonstrate the validity of the experiment,FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.t.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.25 no.3
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• pp.88-96
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• 2012

Objectives : We investigated the skin properties on the periorbital region and cheek of Korean female according to age pattern by 7year based on Sang Go Cheun Jin Ron (上古天眞論) in So Moon (素問,) Methods : 49 Korean females, aged 21-56 years ($39.54{\pm}10.04$ years) were participated in this study. We measured the skin properties of periorbital region and cheek with SkinTouch (Amorepacific, Korea). Skin moisture, sebum, elasticity, lightness, roughness, area of wrinkle, depth of wrinkle were assessed. Results : Differences were noticed depending on the site and age. The level of moisture was higher on the eyelid than crow's feet. The level of lightness and elasticity were lower on the periorbital region than cheek. Skin lightness was highest on group1(under 28y) and lowest on group5(over 49y). Skin roughness was highest on group1(under 28y) and lowest on group4(over 42y under 49y). The level of wrinkle are was lowest on group1(under 28y) and highest on group 5(over49y). The level of wrinkle depth was lowest on group1(under 28y) and highest on group 4(over 42y under 49y). Conclusion : Unique aging pattern by 7 years of female is reflected to diverse skin properties of eyes. It can be possible to apply the theory on Sang Go Cheun Jin Ron (上古天眞論) to practical use in dermatology and cosmetic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.263-263
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• 2010

High temperature annealing is required to synthesize graphene using CVD. When thin metal catalyst is used for the synthesis, the high temperature pre-annealing makes the thin catalyst highly agglomerated. We investigated the agglomeration effect on the shape of the synthesized graphene. It is found that high temperature annealing makes randomly distributed many hole or blister on metal catalyst, and the synthesized graphene features floral pattern around the hole. The floral patterns of graphene turned out to be multi-layers and higher D peaks in raman spectrum.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.147-155
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• 2002

In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.

• Journal of Mechanical Science and Technology
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• v.18 no.3
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• pp.443-452
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• 2004

For stereo lithography process, accuracy of prototypes is related to laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and etc. An accurate prototype is obtained by using appropriate process parameters. In order to determine these parameters, the stereolithography (SLA) machine using neural network was developed and efficiency of the developed SLA machine was compared with that of the traditional SLA. Optimum values for scan speed, hatching spacing and layer thickness improved the surface roughness and build time for the developed SLA.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1920-1922
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• 2003

We have fabricated the pyrex glass microlens using thermal reflow process. Fabricated microlens is the plano convex refractive type and was fabricated with pyrex glass-Si anodic bonding wafer. The etched circle or cylindrical pyrex glass pattern was melted in a furnace $800^{\circ}C$ to $900^{\circ}C$ for about 15min. The surface roughness of the microlenses was measured by the AFM and average surface roughness of the microlenses was below 15min. The radius of curvature of the microlens was measured with phase shift interferometer.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.100-106
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• 2021

This paper presents a study on the improvement of the machining quality of sculptured-surfaces of molds according to the shape and posture of the tool. In the existing 3-axis machining, the methods using the ball end-mill and radius end-mill were analyzed for various cutting patterns and compared with those of the 5-axis machining. It was observed that the 5-axis machining using a ball end-mill obtained the finest surface roughness, and for the 3-axis machining, the optimal results were obtained for the one-way machining using a radius end-mill.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.177-183
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• 1994

The ball-end milling process is widely used in the die/mold industries, and it is very suitable for the machining of free-from surfaces. However, cusps(or scallops) remaining at the machined part along the cutter paths require anothe finish process such as polishing or grinding. In this study, a high sped micro ball-end milling method has been suggested for the finish of free- form surfaces. A new tool path which makes the geometrical roughness of workpiece be constant through the machined surface has been developed. In the high speed machining of micro ball-end muling experimets, the developed tool paths have been successfully applied. And it was concluded that the surface roughness from this finish cuts of micro ball-end milling process was acceptable.

• Journal of Powder Materials
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• v.22 no.3
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• pp.169-174
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• 2015

The optical film for light luminance improvement of BLU that is used in LCD/LED and retro-reflective film is used as luminous sign consist of square and triangular pyramid structure pattern based on V-shape micro prism pattern. In this study, we analyzed machining characteristics of Cu-plated flat mold by shaping with diamond tool. First, cutting conditions were optimizing as V-groove machining for the experiment of micro prism structure mold machining with prism pattern shape, cutting force and roughness. Second, the micro prism structure such as square and triangular pyramid pattern were machined by cross machining method with optimizing cutting conditions. Burr and chip shape were discussed with material properties and machining method.

• Korean Journal of Applied Biomechanics
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• v.18 no.3
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• pp.1-10
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• 2008

One of the major factors affecting maneuverability of an athlete is frictional force caused at an outsole of his shoe. The magnitude of the frictional force is closely related to pattern and hardness of outsole and roughness of ground or floor. This study then focuses on the effect of outsole pattern of sports shoes on the frictional force. After surveying outsole patterns of sports shoes in markets, we select 4 types of outsole patterns, such as straight, W, O, and wave as primary outsole patterns of sports shoe and we also select depth, pitch and slope as design parameters of each pattern. Corresponding to those patterns and design parameters, various outsole specimen are prepared for frictional experiments. After performing frictional tests with those specimen, coefficients of friction(COF) are collected and analyzed with a statistical tool to draw useful conclusion.