• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.231-236
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• 2006

Single-mode planar waveguide type UV sensor was fabricated using SU-8 and photochromic dye. Polymer waveguide was fabricated $10{\mu}m$ width and $2{\mu}m$ thickness for single-mode operation. The UV sensor had an absorbance with $0.0396{\sim}0.114$ absorbance/mW respectively when the 5 mm sensing area was irradiated with UV for 3 sec. And sensor had a linear properties by sensing area variation. Proposed single-mode sensor had more excellent properties of UV sensitivity than other UV sensors.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.7-7
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• 2011

Poly(ethylene terephthalate)(PET) is one of the most widely used materials in textile industry. It can have a low cost, silk-like handle, and excellent mechanical properties. Low thermal stability of PET had been a common problem limiting its high temperature application. The polyester have been known to have the disadvantage of degradation under ionized irradiation compared to crosslikable polymers such as polyethylene, polypropylene and polystylene. To improve thermal stability of PET, the PET films were photocrosslinked by UV irradiation. A hydrogen-abstractable photoinitiator was used to photocrosslink of PET by continuous UV irradiation. Photoinitiator addition increased the gel fraction. The photocrosslinking was attributed to the recombination of PET radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of the PET polymer chains by the added photoinitiator. Also the crosslinked PET showed higher thermal stability and mechanical strength with increasing UV energy. Polyester type films such as poly(ethylene naphthalate)(PEN) and poly(butylene terephthalte)(PBT) were also increased the gel fraction and improved thermal stability and mechanical properties by UV irradiation.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.297-302
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• 2014

ZnS nanowires were synthesized in order to investigate $NO_2$ gas sensing properties. They were grown on the sapphire substrate using ZnS powders. SEM (scanning electron microscopy) showed the diameter and length of the ZnS nanowires were approximately in the range of 50 - 100 nm and a few $10s\;{\mu}m$, respectively. They were also found to be composed of Wurtzite- structured single crystals from TEM (transmission electron microscopy) analysis. $NO_2$ gas sensing performance of the ZnS nanowire was measured with electrical resistance changes caused by $NO_2$ gas with a concentration of 1-5ppm. The sensor was UV treated with an intensity of $1.2mW/cm^2$ to facilitate charge carrier transfer. The responses of the ZnS nanowires to the $NO_2$ gas at room temperature, treated with UV of two different wavelengths of 365 nm and 254 nm, are measured to be 124.53 - 206.87 % and 233.97 - 554.83%, respectively. In the current work, the effect of UV treatment on the gas sensing performance of the ZnS nanowires was studied. And the underlying mechanism for the electrical resistance changes of the ZnS nanowires by $NO_2$ gas was also discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.8-15
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• 2018

Films with special properties (e.g., water-repellent films, optical films, anti-reflection films, and flexible films) are referred to as functional films. Recently, there has been interest in fine patterning methods for film fabrication. In particular there have been many studies that use a UV nanoimprint process involving a UV curing method. In this paper, a polymer film was fabricated by the UV nanoimprint process with a micro-pattern, and its durability was evaluated by a wear test and a nano-indentation test. The film mechanical properties (such as coefficient of friction, hardness, and modulus of elasticity) were measured. Moreover, the choice of PUA type resin used in the UV nanoimprint process was confirmed to impact the durability of the thin film. Despite making the polymer film samples using the same method and PUA type resin, different coefficient of friction, hardness, and modulus of elasticity values were obtained. PUA 4 resin had the most favorable coefficient of friction, hardness, and modulus of elasticity. This material is predicted to produce a high durability functional film.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.61-72
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• 2014

Study on effluent organic matter (EfOM) characteristic and removal efficiency is required, because EfOM is important in regard to the stability of effluents reuse, quality issues of artificial recharge and water conservation of aqueous system. UV technology is widely used in wastewater treatment. Many reports have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on EfOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics. The high intensity of pulsed UV would mineralize EfOM itself as well as change the characteristics of EfOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of EfOM. The objective of this study is to investigate the effect on EfOM, chlorine residual, and chlorinated DBPs formation with low pressure and pulsed UV treatment. The removal of organic matter through low pressure UV treatment is insignificant effect. Pulsed UV treatment effectively removes/transforms EfOM. As a result, the chlorine consumption is changed and chlorine DBPs formation is decreased. However, excessive UV treatment caused problems of increasing chlorine consumption and generating unknown by-products.

• Textile Coloration and Finishing
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• v.13 no.5
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• pp.10-10
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• 2001

The Purpose of this study was to investigate spectrophotometric characteristics of Korean knotweed extracts. The properties were evaluated by it′s extracting solvent, effect of metallic ion, variations of pH values and effect of light exposure. The results were as following; The highest absorbance was found in methanol extract of Korean knotweed, while the lowest absorbance was carbon tetrachloride extract. The UV-vis. spectra of Korean knotweed colors in several solvents showed hypsochromic shift of n-π/sup ＊/ transition with the polarity of solvent. Absorbance and peak of UV-vis. spectra of Korean knotweed colors became lower and broader by addition of metallic ion. The light stability in irradiation with xenon ]amp of the color solution with Cu were higher than those of Al and Fe. The UV-vis. spectra of Korean knotweed extracts in various pH values showed bathochromic shift under alkaline condition, and their peaks disappeared after 5 hours exposure.

• Textile Coloration and Finishing
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• v.13 no.5
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• pp.298-305
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• 2001

The Purpose of this study was to investigate spectrophotometric characteristics of Korean knotweed extracts. The properties were evaluated by it's extracting solvent, effect of metallic ion, variations of pH values and effect of light exposure. The results were as following; The highest absorbance was found in methanol extract of Korean knotweed, while the lowest absorbance was carbon tetrachloride extract. The UV-vis. spectra of Korean knotweed colors in several solvents showed hypsochromic shift of $n->\pi^*$ transition with the polarity of solvent. Absorbance and peak of UV-vis. spectra of Korean knotweed colors became lower and broader by addition of metallic ion. The light stability in irradiation with xenon ]amp of the color solution with Cu were higher than those of Al and Fe. The UV-vis. spectra of Korean knotweed extracts in various pH values showed bathochromic shift under alkaline condition, and their Peaks disappeared after 5 hours exposure.

• Textile Coloration and Finishing
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• v.14 no.4
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• pp.223-228
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• 2002

Cotton fabric was treated with $TiO_2$-PEG600 dispersion colloid by pad-dry-cure and wet-fixation process to improve the performance properties as well as UV-cut effect. As the concentration of $TiO_2$/PEG increased tensile strength, crease resistance, stiffness of treated cotton fabric increased. Application of wet-fixation method provided a further improvement in tensile strength, crease resistance, stiffness of treated cotton fabric. Cotton fabric treated with $TiO_2$/PEG was more efficient in UV-cut property than untreated cotton.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.342-347
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• 2005

Photocurable hyperbranched acrylates were prepared from acrylic acid and hyperbranched polyol (HBP-16, 32, 64). Physical properties of three kinds of photocurable hyperbranched acrylated were investigated. Thermal stability of UV cured film measured by TGA shifted to higher temperature with increasing of functionality. Hardness, abrasion resistance, and tensile strength of UV cured film also increased with increasing functionality of acrylate. Weathering test for UV cured film showed the value of yellow index increased with increasing functionality of acrylate.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.3
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• pp.61-80
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• 1998

To investigate in influence of photosensitizer used with benzophenone(BP) in the curing rate and physical properties of UV curable hard coating on plastic, we prepared UV curable clear and pigmented coatings with DEA, DMA, NPM and TEA as photosensitizer, respectively. The curing rate calculated from the decrease of the absorbance of acrylic double bond measured by FT-IR spectroscopy increased s follows; DEA>DMA>NPM>TEA. this order could be explained by the reactivity of diethylamino group of DEA and the ease of formation of activated complex between BP and photosensitizer during the curing process. In UV curable pigmented coatings, the order of curing rate increased as follows; DEA>DMA>TEA>NPM. It was found that the curing rate of the pigmented coating can be increased by light scattering of TiO$_2$. The hardness of coating film cured by photosensitization of DEA and DMA is higher than other photosensitizers due to the crosslinking reaction of DEA and DMA radical bound to polymer backbone.