• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.358-361
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• 2004

The photocatalytic degradation of Endocrine Discruptors, dibuthyl phthalate(DBP) has been investigated over TiO$_2$ photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., reaction time, light intensity, pH and additive on the degradation rate of aqueous solution of Endocrine Discruptors has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Endocrine Discruptors solutions.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.883-888
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• 2007

Investigation of improving the properties of UV detector which uses the wide bandgap of ZnO are under active progress. The present study focused on the design and fabrication of i-ZnO/p-inversion $layer/n^--Si$ Epi. which is characterized with very thin p-type inversion layer for UV detectors. The i-ZnO thin film for achieving p-inversion layer which was grown by RF sputtering at $450^{\circ}C$ and then annealed at $400^{\circ}C$ in $O_2$ gas for 20 min shows good intrinsic properties. High (0002) peak intensity of the i-ZnO film is shown on XRD spectrum and it is confirmed by XPS analysis that the ratio of Zn : O of the i-ZnO film is nearly 1 : 1. Measurement shows high transmission of 79.5 % in UV range (< 400 nm) for the i-ZnO film. Measurement of $V_r-I_{ph}$ shows high UV photo-current of 1.2 mA under the reverse bias of 30 V.

• 한국기계가공학회지
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• 제11권1호
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• pp.62-67
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• 2012

Recently UV laser is widely used to process micro parts using various materials such as polymers, metals and ceramics because it has a very high intensity at the focused spot area. It is generally known that there are still some difficulties for alumina($Al_2O_3$) ceramics to directly make micro patterns like holes and lines on the surface of working material using 355nm UV laser because the alumina has a very low absorption coefficient at that wavelength. But nowadays new alumna with nano-porous holes is developed and applied to advanced micro functional parts of IT, BT and BT industries. In this paper, we are going to show the mechanism of photo-thermal ablation for nano-porous ceramics. Inside hole there is a lot of multiple reflections along the depth of hole. Experimentally we can find the micro hole drilling and micro grooving on the surface of nano-porous alumina.

• 상하수도학회지
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• 제10권4호
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• pp.64-72
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• 1996

The effect of $O_3$, $O_3/pH$, and $O_3/H_2O_2$, $O_3/UV$, and $H_2O_2/UV$ advanced oxidation process(AOP) were investigated for the treatment of tetrachloroethylen(PCE) at various condition. The removal efficiency of 10, 20, and 30ppm PCE by ozonation were almost same, only about 60%. And pseudo first-order rate constants, ko for overall oxidation was about 0.097($min^{-1}$). In the $O_3/pH$ AOP experiment for the 20ppm PCE, the removal rate of PCE increased with the increase of pH. However, mineralization rate of PCE at pH 7 was higher than at pH 10. In the $O_3/H_2O_2$ AOP, the removal rate of PCE was the highest at peroxide-to-ozone dosage ratio of about 0.9, which PCE was removed over 99.95%. Despite 42% of PCE was directly photolyzed by the UV irradiation, the removal efficiency of PCE by $O_3/UV$ AOP was only about 70%. In $H_2O_2/UV$ AOP, the removal efficiency of PCE increased to about 98% in proportion to the $H_2O_2$ injection concentration at constant UV intensity of 5W/l.

• Animal cells and systems
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• 제4권3호
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• pp.293-297
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• 2000

The present investigation was performed to elucidate the effect of pretreatment with low dose ultraviolet radiation (UV) and ethyl methanesulfonate (EMS) on cell survival by trypan blue dye exclusion method and plasma membrane glycoconjugates by lectin-cytochemistry in sarcoma 180 (S180) cells. Pretreatment with 2 J/$m^2$ UV or 2 mM EMS increased the percentage of survival of cells subsequently treated with high dose UV (10 or 20 J/$m^2$) or EMS (10 or 20 mM), respectively. Staining intensity of concanavalin A (Con A) of the cells pretreated with 2J/$m^2$ UV or 2 mM EMS and subsequently treated with 10 or 20 mM EMS was stronger than that of the cellstreated with 10 or 20 mM EMS. These results suggest that there is an adaptive response on cell survival to EMS or UV in S180 cells. And the results show a change in mannose-containing glycoconjugates of plasma membrane in S180 cells pretreated with EMS or UV and subsequently treated with EMS.

• 한국표면공학회지
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• 제47권6호
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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.

• Tribology and Lubricants
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• 제35권3호
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• pp.151-157
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• 2019

Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.

• Journal of Photoscience
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• 제9권2호
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• pp.158-161
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• 2002

UV-B radiation gives harmful effects on plants, such as production of several types of DNA lesions, and growth inhibition. On the other hand, plants have some protective mechanisms, including filtering effect due to accumulation of phenolic compounds in epidermal cells and reactivation of DNA lesions, which are enhanced by UV-B irradiation. We have investigated the mechanism of UV-B effects on plants using cucumber seedlings as plant materials. Cucumber plants were cultivated in an artificially lit growth chamber. Supplemental UV-B irradiation, of which intensity was almost equal to the level of natural sunlight, retarded the growth of first leaves. The growth retardation must result trom the inhibition of cell division and/or cell growth. Microscopical observation of leaf epidermis suggested that the growth retardation might be mainly caused by cell growth inhibition. The retardation was, however, restored within 2 or 3 days after the termination of UV-B irradiation. It is known that UV-B irradiation lowers the activity of photo system II (PS II). In the present experimental conditions, however, UV-B irradiation has little effect on PS II activity as estimated by chlorophyll fluorescence. The stomatal conductance, a major factor determining photosynthetic rate, of first leaves increased during the growth. The increase of stomatal conductance was suppressed by UV-B irradiation and restored by termination of the irradiation. It has not been clear, however, what mechanisms are involved in the suppression of increase of stomatal conductance.

• 한국지반환경공학회 논문집
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• 제7권4호
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• pp.5-13
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• 2006

본 연구는 지표수에서 휴믹산을 포함한 중금속을 제거하기 위해 $UV/TiO_2/H_2O_2$ 공정을 적용하여 각 실험인자에 대한 처리효율을 실험적으로 검토하였다. 휴믹산과 중금속을 제거하는데 있어 $UV/TiO_2/H_2O_2$ 공정은 $UV/TiO_2$ 공정보다 훨씬 더 높은 제거효율을 보여 주었다. $TiO_2$ 주입량과 UV 세기를 증가시킴에 따라 휴믹산과 중금속 제거율은 증가했다. 그러나 0.3 g/L 이상의 $TiO_2$ 주입량에서는 제거율이 감소했다. 산화제로 사용된 과산화수소의 첨가는 휴믹산과 중금속 제거에 있어 긍정적인 효과를 보여주었으며 특히 50 mg/L의 과산화수소 농도에서 가장 좋은 제거효율을 나타내었다.

• 대한환경공학회지
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• 제29권9호
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• pp.1020-1026
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• 2007

전 세계적으로 병원성 미생물에 의한 오염과 감염 및 발병의 사례가 급증함에 따라 병원성 미생물을 효율적으로 제어하는 기술에 대한 관심이 매우 증가하고 있다. 병원성 미생물을 환경에서 제어하는 연구는 대다수 수처리 공정과 같이 물에서 이루어지는 소독과 관련되어 진행되어 왔고, 표면에서의 소독에 관련된 연구는 매우 부족하였다. 본 연구는 UV 소독 방법을 표면에 분포된 미생물의 불활성화에 대해서 적용하여 살펴보았고, 소독 모델을 통해서 정량화하였다. 특히, 생물테러용 무기로 잘알려진 탄저균(Bacillus anthracis)의 지표 미생물인 바실러스 포자(Bacillus subtilis spore)에 대해서 UV를 이용한 표면 소독시 매우 빠른 불활성화를 볼 수 있었으며, 2 log(99%) 불활성화를 위한 IT 값은 14.5 $mJ/cm^2$으로 나타났다. UV에 의한 미생물 불활성화는 화학적 소독제의 경우와 달리 온도에 의한 영향은 나타나지 않았으나, 표면 거칠기(surface roughness)에 의한 뚜렷한 tailing off 현상이 나타났다.