• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.3
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• pp.17-30
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• 2011

The polarizer is an important optical element used in a variety of applications. Nano-wire grid polarizers in the form of sub-wavelength metallic gratings are an attractive alternative to conventional polarizers, because they provide high extinction ratio. This study has been carried out to fabrication of the 17inch area size nano-wire grid polarizer(NWGP) The master for NWGPs with a pitch of 200nm and the area size $730mm{\times}450mm$ were fabricated using laser interference lithography and aluminum sputtering and wet etching. And The NWGP fabrication process was using by the Roll to-Roll UV imprinting and was applied to flexible PET film. The results were a transmission of light (Tp) 46.7%, reflectance (Rs) 40.1% and Extinction ratio of above 16 for the visible light range.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.167-183
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• 2017

Zinc oxide (ZnO) is one of the most versatile semiconductors, and one-dimensional (1D) ZnO nanostructures have attracted significant interest for use in ultraviolet (UV) lasers, photochemical sensors, and photocatalysts, among other applications. It is known that 1D ZnO nanowires can be fabricated readily owing to the anisotropic growth of ZnO along the [0001] direction. However, this type of growth results in a decrease in the surface area of the (0001) plane, which plays a vital role not only in UV lasing but also in the photocatalytic process. Thus, we attempted to synthesize ZnO crystals with an increased polar surface area by controlling the crystal growth process. The purpose of this review is to propose a simple route for the synthesis of plate-like ZnO crystals with highly enhanced polar surfaces and to explore their feasibility for use in UV lasers as well as as a photocatalyst and antibacterial agent. In addition, we highlight the recent progress made in the pilot-scale synthesis of plate-like ZnO crystals for industrial applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.108-111
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• 2001

ZnO thin films on (001) sapphire substrates knave been deposited by pulsed laser deposition(PLD) technique for light emitting device applications. We have controlled the emission intensity of UV and visible light, depending on film thickness and various post-annealing time. UV emission became strong as the thickness of ZnO thin films increased. The intensity of visible light was strong as post-annealing temperature increased. The optical properties of the ZnO thin films were characterized by PL(photoluminescence) and the structural properties of the ZnO were characterized by XRD for the application of ZnO light emission device.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.3
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• pp.279-285
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• 2015

Hyperpigmentation on face is a highly anxiety-producing symptom, especially for women from the aspect of beauty. Pigmentation of the skin is related to the amount of melanin that provides protection against UV radiation. In vivo reflectance confocal microscopy is a non-invasive imaging tool allowing visualization of the skin without tissue alteration, by placing a microscopy directly on the living skin. The aim of this study was to develop the new evaluation method of whitening effects using in vivo reflectance confocal microscopy and to validate other instruments for measuring skin colors, and UV-induced hyperpigmentation was elicited on the inside skin of the forearm. It suggested that the new method for whitening effects using the confocal microscopy was useful to evaluate the de-pigmentation products and to easy for understanding to customers.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.312-320
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• 2003

The basic mechanistic aspects of the interaction and practical considerations related to polymer ablation were briefly reviewed. Photochemical and photothermal effects, which highly depend on laser wavelength have close correlation with each other. In this study, multi-scanning laser ablation processing of polymer with a DPSS (Diode Pumped Solid State) 3rd harmonic Nd:YVO$_4$ laser (355 nm) was developed to fabricate a three-dimensional micro shape. Polymer fabrication using DPSSL has some advantages compared with the conventional polymer ablation process using KrF and ArF laser with 248 nm and 193 nm wavelength. These advantages include pumping efficiency and low maintenance cost. And this method also makes it possible to fabricate 2D patterns or 3D shapes rapidly and cheaply because CAD/CAM software and precision stages are used without complex projection mask techniques. Photomachinability of polymer is highly influenced by laser wavelength and by the polymer's own chemical structure. So the optical characteristics of polymers for a 355 nm laser source is investigated experimentally and theoretically. The photophysical and photochemical parameters such as laser fluence, focusing position, and ambient gas were considered to reduce the plume effect which re-deposits debris on the surface of substrate. These phenomena affect the surface roughness and even induce delamination around the ablation site. Thus, the process parameters were tuned to optimize for gaining precision surface shape and quality. This maskless direct photomachining technology using DPSSL could be expected to manufacture tile prototype of micro devices and molds for the laser-LIGA process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.519-520
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.663-664
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.278-279
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• 2003

최근 정보, 전자, 광, 반도체 등 각종 첨단산업에서는 다양한 형태와 재료의 가공방법이 요구되고 있으며 요구되는 부품의 정밀도도 마이크로 단위에서 서브 마이크로 단위까지의 고도의 정밀도를 요하는 기술들이 점차 늘어가고 있다. 또 더욱 더 소형화 되어가고 있는 마이크로 부품은 기존의 2차원 및 준 3차원에서 완전한 3차원 형태의 기술로 발달하고 있으며 현재 연구가 활발히 진행되고 있는 MEMS 분야에서 구동부 부품이라든가 또는 그를 지지하는 구조체로 쓰일 수 있어 그 활용 가치는 응용에 따라 폭이 넓다고 할 수 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.231-232
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• 2008

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.15-20
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• 2007

We fabricated ZnO thin films on quartz substrate using pulsed laser deposition method and investigated structural and optical properties of ZnO thin films with various substrate temperatures. Regardless of the substrate temperature variation, all ZnO thin films had grown to (002) and the thin film deposited at 400 $^{\circ}C$ exhibited an excellent crystallinity having 0.24$^{\circ}$ of Full-Width-Half-Maximum (FWHM). In the result of photoluminescence property, UV and deep-level emission peaks were observed in all ZnO films and the emission peaks were changed with various substrate temperatures. An highest UV emission was exhibited on the specimen deposited at 400 $^{\circ}C$ and the FWHM of UV peak was 14 nm. The optical transmittance was about 85 % in visible region regardless of the substrate temperature. The comparison result of the bandgap energies obtained from optical transmittance and UV emission centers, the two values were about the same. From these results, it is found that UV emission center has close relationship with near band edge emission of ZnO thin film.