• 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.

• Journal of Adhesion and Interface
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• v.19 no.2
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• pp.74-82
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• 2018

Many methods for cross-linking acrylic PSAs have been discussed previously. For high cross-linking density, epoxy functionalized monomer and methyl aziridines as cross-linking agents were used in this study. Additionally, photopolymerization using different UV doses was investigated to synthesize a binder because of its rapid productivity. FT-IR analysis, curing behaviours and adhesion performance were examined for the relationship between UV doses and temperature as curing conditions. According to the results, the gel fraction was over 50% even at $120^{\circ}C$ after UV curing at a dose of $800mJ/cm^2$. On the other hand, while gel fractions of all samples reached approximately 80% only at $180^{\circ}C$ in thermal curing for 1 hour, gel fractions of the samples after thermal curing for 3 hours increased rapidly above $120^{\circ}C$ regardless of UV doses and reached approximately 100% at $180^{\circ}C$. This means that the second cross-linking reaction, esterification, is mainly dependent on the curing temperature.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.739-746
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• 2014

In this study, The effects of empty bed contact time (EBCT) and water temperature on the biodegradation of 8 UV filters in biological activated carbon (BAC) process were investigated. Experiments were conducted at two water temperatures (7 and $18^{\circ}C$) and three EBCTs (5, 10 and 15 min). Increasing EBCT and water temperature increased the biodegradation efficiency of UV filters in BAC column. EHMC and BZC were the highest biodegradation efficiency, but BP and 4-MBC were the lowest. The kinetic analysis suggested a first-order reaction model for biodegradation of 8 UV filters at various water temperatures and EBCTs. The first-order biodegradation rate constants ($k_{bio}$) of 8 UV filters ranging from $0.2730{\sim}0.6365min^{-1}$ at $7^{\circ}C$ to $0.4824{\sim}0.8743min^{-1}$ at $18^{\circ}C$. By increasing the water temperature from $7^{\circ}C$ to $18^{\circ}C$, the biodegradation rate constants ($k_{bio}$) were increased 1.5~2.1 times.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.133-137
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• 2001

In this research, we synthesized various photo-crosslinkable polyimide based polymers. The control of pretilt angles for a nematic liquid crystal (NLC) using the photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimetric analysis (TGA) measurement until 450C. High pretilt angles of the NLC were otained by polarized UV exposure on the photopolymers containing biphenyl (BP), decyl (de), and cholesteryl (chal) groups, respectively. However, low pretilt angles of the NLC were measured by polarized UV exposure on the photopolymers containing fluorine and chalcone groups. The high NLC pretilt angles generated are attributable to the biphenyl and alkyl moieties, and the photodimerized chalocone group of the photopolymers. Additionally, good voltage-transmittance and response time characteristics were observed by UV exposure on the photopolymers.

• Laser Solutions
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• v.13 no.3
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• pp.13-18
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• 2010

In this paper, polyimide (PI) surface was modified by UV Laser with a low laser fluence and investigated changes of surface geometry and chemical characteristics by SEM (scanning electron microscope), X-ray diffraction (XRD), XPS (x-ray photoelectron spectroscopy) and the measurements of contact angle of water. PI surface was peeled off and modified with microstructure fabrications by photochemical ablation over the laser fluence of 50 mJ/cm2. As laser fluence increased, delamination of PI surface was occurred largely and strongly. In chemical characteristics, the O/C and N/C atomic ratios increased and contact angle decreased from $80^{\circ}$ to $40^{\circ}$.

• Korean Journal of Pharmacognosy
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• v.48 no.1
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• pp.93-96
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• 2017

Ephedra alkaloids, (-)-ephedrine, (+)-pseudoephedrine, (-)-N-methylephedrine, (+)-N-methylpseudoephedrine, (-)-norephedrine and (+)-norpseudoephedrine, from ephedra herb are sympathomimetic agonists causing an increase of metabolism, blood pressure and perspiration. In this study, we developed the validation method of (+)-pseudoephedrine and (-)-ephedrine, two major ephedra alkaloids in Ephedra spp., by high-performance liquid chromatography-ultraviolet spectrometer (HPLC-UV). HPLC analysis was performed using a HECTOR-M C18 column operating at $35^{\circ}C$, and UV detection at 215nm. The mobile phase used a gradient flow with 25 mM SDS in water (A) and acetonitrile (B).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.3
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• pp.122-126
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• 2006

In this study, composite materials were put to dry interfacial treatment by use of plasma technology It has been presented that the optimum parameters for the best wettability of the samples at the time of generation of plasma were oxygen atmosphere, 0.1 Torr of system pressure, 100 W of discharge power, and 3 minutes of discharge time. The decrease in surface potential of charged samples by corona discharge indicates that the amount of accumulated electrical charges reduces and the charges that have been injected lessen rapidly when the duration of UV irradiation increases. The surface resistivity and the tensile strength of plasma treated samples, a longer UV irradiation time resulted in decreased insulation.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.11
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• pp.1859-1869
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• 2010

This study provides improved wrinkle recovery and UV protection capabilities as well as an antibacterial and deodorizing function to linen fabrics for summer shirts. The results obtained from this study are as follows. By setting catalyst concentration to 1.2% and DMDHEU concentration to 6% respectively and applying a heat treatment to them at $160^{\circ}C$ for 5 minutes, the decrease of fabric strength could be minimized and the crease resistance of linen fabrics improved. Compared to the treatment with DMDHEU only, the crease resistance of linen fabrics could be maintained and degradation of their properties could be more effectively prevented by applying the mixture of the UV absorber and the nano silver to the DMDHEU resin. The UV protection of fabrics could be improved by adding the UV absorber. Although the separate treatment of resin or the nano silver had no effect on the improvement of the UV protection properties for treated fabrics, they could increase the UV protection capability when they were combined with the UV absorber. Linen fabrics could possess an antibiosis and deodorizing capability by applying the mixture of the UV absorber, the nano silver, and the resin. The UV protection, crease resistance and flexibility of finished fabrics were maintained even after laundering. Washed treated fabrics maintained excellent antibiosis and odor free capabilities compared to untreated fabrics.

• Membrane and Water Treatment
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• v.8 no.3
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• pp.211-223
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• 2017

In this work, an attempt was made to compare the effects of UV irradiation on the intrinsic and separation properties of membranes made of two different polymeric materials, i.e., polyvinylidene fluoride (PVDF) and polyetherimide (PEI). The changes on membrane structural morphologies and chemical characteristics upon UV-A exposure (up to 60 h) were studied by FESEM and FTIR, respectively. It was found that cracks and fractures were detected on the PVDF-based membrane surface when the membrane was exposed directly to UV light for up to 60 h. Furthermore, the mechanical strength and thermal stability of irradiated PVDF-based membrane was reported to decrease with increasing UV exposure time. The PEI membrane surface meanwhile remained almost intact throughout the entire UV irradiation process. Filtration experiments showed that the permeate flux of UV-irradiated PVDF membrane was significantly increased from approximately 11 to $16L/m^2.h$ with increasing UV exposure time from zero to 60 h. Oil rejection meanwhile was decreased from 98 to 85%. For the PEI-based membrane, oil rejection of >97% was recorded and its overall structural integrity was marginally affected throughout the entire UV irradiation process. The findings of this work showed that the PEI-based membrane should be considered as the host for photocatalyts incorporation if the membrane was to be used for UV-assisted wastewater treatment process.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.38-44
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• 2015

This study was conducted to investigate the effects of electrolyzed water (EW) and hot-air-drying with ultraviolet light (UV) to reduce coliform bacteria of Undaria pinnatifida (UP). The UP was washed in the order of 15% EW, tap water (TW), and distilled water (DW) under following conditions: 15% EW for 10 min (washing: 1 time), TW for 1 min, and DW for 10 min (washing: 5 times). Viable cells, coliform, and mold counts were at 10²-10³ CFU/g in untreated samples. After EW treatment, viable cells, coliform, and molds were not detected in whole samples or on the surface of UP. But, after hot-air-drying at 48°C for 48 h, the number of viable cells, coliform, and molds were 10¹-10⁵ CFU/g. After hot-air-drying at 48°C for 48 h with UV (12-48 h), viable cells, coliform, and molds were not detected in whole samples or on the surface of UP. In respect of color value, there were no significant changes. In sensory evaluation, the UP with hot-air-drying with UV (12 h) had the highest score in overall preference among UV treatment groups. These results suggest that the treatments at 15% EW for 10 min and hot-air-drying at 48°C for 48 h with UV (12 h) were effective to reduce coliform bacteria of the dried Undaria pinnatifida.