• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.875-880
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• 2016

In this study, we proposed an effective and simple way to directly generate wrinkle patterns on a curved surface. A curved surface was prepared using a 3D printer and an UV (Ultraviolet)-lighting system was utilized to weakly polymerize the UV-curable thin resin layer coated on the surface, resulting in a gradient of material properties in the layer thickness. Subsequently, a thermal curing process was conducted to generate microscale wrinkles by compressive forces that were generated during complete curing. Wrinkle shapes from 5, 15, 25 sec of UV-light exposure were compared. With increasing UV-exposure, the line-width of wrinkles became thicker due to much higher strength of skin zone. The results indicated that the proposed fabrication process could be utilized for surface modification in diverse research fields.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.433-436
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• 2018

A total internal reflection (TIR) linear lens of size $190(W){\times}5(D){\times}2.1(H)mm^3$ has a directivity of $25^{\circ}$ and was made of a polydimethysiloxane (PDMS) silicone resin with a refractive index of 1.4 and a transmittance of 93% at 365 nm UV wavelength. A light source with a size of $190{\times}25.5mm^2$ was fabricated by installing a TIR linear lens on a chip on board (COB) type LED module mounted with a $1.1{\times}1.1mm^2$ size UV LED. The optical characteristics of the light source showed a maximum irradiation density of $3,840mW/cm^2$ at a working distance of 5 mm and a high uniformity of 91.6% over a $150{\times}25mm^2$ irradiation area. The thermal characteristics of the light source were measured at a supply current of 500 mA. The saturation temperature was reached after 30 min of operation, and measured to be $95^{\circ}C$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1998.11a
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• pp.138-141
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• 1998

To evaluate the color change of the opaque resin materials, a measuring system including PAS(photodegradation acceleration system) was constructed. Xenon lamp is used as a light source in the PAS, and the radiant energy from the lamp is irradiated to the samples through serveral high-pass filters with cut-off wavelength in UV and visible region. The color difference of the samples were measured by using the measuring system with a spectrophotometer(CM-2002) and a computer. The result showed that the opaque resin materials changed severely in their color in the wavelength of UV region and changed a little in the wavelength of visible region.

• Journal of Technologic Dentistry
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• v.42 no.3
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• pp.202-207
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• 2020

Purpose: This study is a comparative analysis of the strain according to deposition in a constant temperature water bath after manufacturing ultraviolet (UV)-cured artificial teeth. Methods: As a control group, 10 ready-made artificial teeth were selected as the first molar on the right side of the maxilla (RT group). Silicone was used as a duplicate of the artificial denture teeth. Experimental teeth were prepared in two groups using the prepared silicone mold. In the first experimental group, the UV-cured resin was injected into the negative silicone, followed by irradiation with a UV-curing machine for 5 minutes (5M group). In the second experimental group, the UV-cured resin was injected into the negative silicone, and then irradiated for 30 minutes using a UV-curing machine (30M group). The one-way ANOVA was performed, and post-test was analyzed by Tukey. Results: When immersed in a water bath for 15 days, it was found to be -0.3% in the RT group, -0.6% in the 5M group, and -0.7% in the 30M group. The results revealed -0.2% in the RT group, 0.2% in the 5M group, and -0.2% in the 30M group when they were in the bath for 30 days. Conclusion: In the water bath, the swelling was greater when deposited for 1 to 15 days, but was less when deposited for 15 to 30 days.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1400-1403
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• 2007

The 3DP(three dimensional printing) technology is one of the SFF(solid freeform fabrication) technologies which has recently come into a spotlight due to its suitability to various field. A manufacturing process of product is using many pattern formation technology. The 3DP technology uses multi nozzle that can fabricate three dimensional object of high speed and accuracy. In this paper, we introduce a development of the office type solid freeform fabrication system. This system is used UV resin and multi-piezo head.

• Journal of the Korean Applied Science and Technology
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• v.17 no.3
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• pp.188-191
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• 2000

A new class of deep UV Photoresist based on the principles of chemical amplification was developed. This photoresist consists of three basic elements: a copolymer, blocked tetrabromobisphenol-A as a dissolution inhibitor and a photosensitive onium salt as a photoacid generator. On irradiation followed by a post exposure bake, tert-butoxycarbonyloxy phenyl group is converted to phenol group. Thus the initially base insoluble resin is converted under UV irradiation to a base soluble resin which may be preferentially removed by dissolution. This new photoresist display high sensitivity, 10 $mJ/cm^{2}$.

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.39-45
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• 2004

Ultraviolet-nanoimprint lithography (UV-NIL) is a promising method for cost-effectively defining nanoscale structures at room temperature and low pressure. A 5${\times}$5${\times}$0.09 in. quartz stamp is fabricated using the etch process in which a Cr film was employed as a hard mask for transferring nanostructures onto the quartz plate. FAS(Fluoroalkanesilane) is used as a material for anti-adhesion surface treatment on the stamp and a thin organic film to improve adhesion on a wafer is formed by spin-coating. The low viscosity resin droplets with a nanometer scale volume are dispensed on the whole area of the coated wafer. The UV-NIL experiments have been performed using the EVG620-NIL. 370 nm - 1 m features on the stamp have been transferred to the thin resin layer on the wafer using the multi-dispensing method and UV-NIL process. We have measured the imprinted patterns and residual layer using SEM and AFM to evaluate the potential of the process.

• Journal of the Korean Vacuum Society
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• v.14 no.1
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• pp.35-39
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• 2005

In the UV-NIL process using an elementwise patterned stamp (EPS), which includes channels formed to separate each element with patterns, low-viscosity resin droplets with a nano-liter volume are dispensed on all elements of the EPS. Following pressing of the EPS, the EPS is illuminated with UV-light to cure the resin; and then the EPS is separated from several thin patterned elements on a wafer. Experiments on UV-NIL were performed on an EVG620-NIL. 50 - 100nm features of the EPS with 3m channels were successfully transferred to 4 in. wafers. Especially, the wafer deformation during imprint was analyzed using the finite element method (FEM) in order to study the effect of the wafer deformation on the UV-NIL using EPS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2396-2401
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• 2009

This study is on development of UV-cured hard coating compounds which have more improved abrasion resistance than existing UV-cured urethane-acrylic resin, to prevent a surface of a widely used PVC tile as a constructive material from being scratched. To make a high abrasion resistant hard coating solution compared to UV-cured urethane-acrylic resin which has no abrasion resistance and been used for PVC tiles, we added powder substances of different abrasion resistant level, $Al_2O_3$(Al-160SG-3), $Al(OH)_3$(SH-8W), $SiO_2$(KS-5000), etc., to the resin, changing their contents from 10% to 30% against quantities of resin, and compounded it using Ring-Mill. After coating PVC tiles with the hard coating solution using bar-coating method that can adjust a thickness, we estimated some surface properties-abrasion resistance, pencil hardness, adhesive power, thickness of coating, and so on. As a result, a hard coating solution added 30% $Al_2O_3$ powder to the resin had the finest surface properties-the first grade in abrasion resistance, H in pencil hardness, 100% in adhesive power, and a hard coating solution which showed excellent solidity and abrasion resistance has smaller particle size, higher powder content, and thicker coating thickness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.227-228
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• 2007