• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.175-176
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.613-614
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• 2011

• Textile Coloration and Finishing
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• v.28 no.2
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• pp.63-69
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• 2016

Poly(butylene terephthalate)(PBT) surface was modified by UV/ozone irradiation and the effect of UV energy on the surface properties of the irradiated PBT films were characterized by the reflectance, surface roughness, contact angles, ESCA, and ATR analyses of the film surface. The surface reflectance, at the short wavelength of visible spectrum of particularly 400nm, decreased with increasing UV energy. And the irradiation roughened the film surface uniformly in the nano scale. The maximum surface roughness increased from 110nm for the unirradiated sample to 303nm at the UV energy of $10.6J/cm^2$. The surface energy of PBT film increased from $50.5mJ/m^2$ for the unirradiated PBT to $58.8mJ/m^2$ at the irradiation of $21.2J/cm^2$. The improvement in hydrophilicity was caused by the introduction of polar groups containing oxygens such as C-O and C=O bonds resulting in higher $O_{1s}/C_{1s}$. The increased dyeability of the modified film to cationic dyes may be resulted from the photochemically introduced anionic and dipolar dyeing sites on the PBT films surfaces.

• Textile Coloration and Finishing
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• v.23 no.2
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• pp.76-82
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• 2011

Ultra High molecular weight polyethylene(UHMWPE) films were photooxidized by UV/ozone irradiation. Reflectance of the irradiated films decreased in the low wavelength regions of visible light, indicating destructive interference of visible light due to roughened surface. The UV treatment developed the nano-scale roughness on the UHMWPE films surface, which increased by two-fold from 82.6 to 156.6nm in terms of peak-valley roughness. The UV irradiation caused the oxygen content of the UHMWPE film surface to increase. Water contact angle decreased from $83.2^{\circ}$ to $72.9^{\circ}$ and surface energy increased from 37.8 to 42.6mJ/$m^2$ with increasing UV energy. The surface energy change was attributed to significant contribution of polar component rather than nonpolar component indicating surface photooxidation of UHMWPE films. The increased dyeability to cationic dyes may be due to the photochemically introduced anionic and dipolar dyeing sites on the film surfaces.

• Fibers and Polymers
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• v.5 no.3
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• pp.225-229
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• 2004

The effect of UV and $^60{Co}$ gamma radiations on the physical and mechanical properties of nylon 6 mono-filaments with different draw ratios has been studied. Specimens were exposed to either up to 25 Mrad of gamma or up to 168 hrs of intense UV irradiation. The results show that nylon mono-filaments exposed to gamma rays, with much higher quantum energy than UV, undergo a larger extent of molecular chain scission. Higher irradiation dose also results in the production of insoluble, macroscopic three-dimensional cross-linked network structure. The amorphous regions with a lower density of cohesive energy (lower molecular orientation) show a higher extent of cross linking reaction whereas amorphous regions with a higher density of cohesive energy (higher orientation) show higher extent of chain scission reaction, irrespective of UV ray or gamma ray irradiation.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2241-2242
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• 2013

• Journal of Environmental Science International
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• v.15 no.7
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• pp.669-676
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• 2006

PAHs are major pollutants that are widely distributed in soil and groundwater environment, so that may be regarded as carcinogens. We investigated the degradation kinetics of PAH in aqueous solution when low pressure UV energy and ultrasonic irradiation were applied. Phenanthrene and pyrene were used as model compounds. The degrees of degradation of these compounds with time were analyzed with a GC/MSD (SIM-mode). UV photolysis experiments showed that phenanthrene was reduced by 90 -67% at initial concentrations of 1 ppm to 8ppm whilst it decreased to 50% at 10 ppm. Under the same conditions pyrene was degraded up to about 75% at lower initial concentrations but the reduction efficiency dropped to a level of 34 to 29% at the higher concentrations above 8 ppm. The reaction orders for phenanthrene and pyrene were found to be zero-th and ca. -0.4th order, respectively, thus implying that the reported assumption of pseudo 1st order reaction for some PAHs would be no longer valid. PAH degradation was roughly proportional to the intensity of UV (number of lamps), exhibiting maximum 92.5% of the degradation efficiency. The solution pH was lowered to 4.4 from 6.4 during the experiments partially because the carbons decomposed by the energy reacted with oxygen radicals to produce carbon dioxides. Ultrasonic irradiation on phenanthrene solutions gave relatively poor results which matched to 50 to 70% of degradation efficiency even at 2 ppm of initial concentration. Phenanthrene was found to be degraded more efficiently than pyrene for the two energy sources. Ultrasound also followed the same reaction kinetics as UV energy on PAH degradation.

• Laser Solutions
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• v.14 no.1
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• pp.14-18
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• 2011

Semiconductor industry demands decrease in line/space dimensions of IC substrates. Particularly for IC substrates for CPU, line/space dimensions below $10{\mu}m/10{\mu}m$ are expected to be used in production since 2014. Conventional production technologies (SAP, etc.) based on photolithography are widely agreed to be reaching capability limits. To address this limitation, the embedded circuit fabrication technology using laser ablation has been recently developed. In this paper, we used a nanosecond UV laser and a picosecond UV laser to fabricate embedded circuit patterns into a buildup film with $SiO_2$ powders for IC substrate. We conducted SEM and EDS analysis to investigate surface quality of the embedded circuit patterns. Experimental results showed that due to higher recoil pressure, picosecond UV laser ablation of the buildup film generated a better surface roughness.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.26-26
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• 2012

The hydrophobic nature of the wool surface give rise to difficult penetration of dye molecules. Among all the methods of modification, graft polymerization is an attractive method to impart a variety of functional groups to a polymer. Grafting has been made by irradiating the light on the polymer in the presence of a solvent containing monomer. The energy source commonly used are high-energy electrons, X-rays, UV and visible light. UV irradiation is a relatively low-energy radiation in comparison with others since it has the least possibility to change bulk properties. In the present paper, a photo-reactive dye was synthesized from quinizarin by the reaction with methacryloyl chloride. The synthesized dye was continuously grafted onto wool fabric at room temperature by UV irradiation. Several key parameters including UV energy, dye concentration and pH have been examined to understand their influence on the photoreactive coloration.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.955-956
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• 2006

Fe-doped $TiO_2$ nanopowders were prepared by mechanical alloying (MA) varying Fe contents up to 8.0 wt.%. The UV-vis absorption showed that the UV absorption for the Fe-doped powder shifted to a longer wavelength (red shift). The absorption threshold depends on the concentration of nano-size Fe dopant. As the Fe concentration increased up to 4 wt.%, the UV-vis absorption and the magnetization were increased. The benefical effect of Fe doping for photocatalysis and ferromagnetism had the critical dopant concentration of 4 wt.%. Based on the UV absorption and magnetization, the dopant level is localized to the valence band of $TiO_2$.