• Environmental Mutagens and Carcinogens
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• v.16 no.1
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• pp.19-23
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• 1996

This study was performed by the sister chromatid exchanges (SCEs) and micronuclei (MN) assays to investigate the adaptive response to ultraviolet light (UV) or ethyl methanesulfonate (EMS) in Chinese hamster ovary (CHO) and Sarcoma 180 (S180) cells. The pretreatment with 1 J/m$^2$ UV or 2 mM EMS decreased the frequency of SCEs induced by the treatment with 5 J/m$^2$ UV or 8 mM EMS in CHO cells. The pretreatment with UV (1 or 2 J/m$^2$) or EMS (1, 2 or 3 mM) did not affect the SCEs induced by the treatment with 7 J/m$^2$ UV or 10 mM EMS in S180 cells. On the other hand, the pretreatment with 1 J/m$^2$ UV or 2 mM EMS decreased the frequency of MN induced by the treatment with 5 J/m$^2$ UV or 8 mM EMS in CHO cells. The pretreatment with UV (1 or 2 J/m$^2$) or EMS (1, 2 or 3 mM) did not affect the frequency of MN induced by the treatment with 7 J/m$^2$ UV or 10 mM EMS in S180 cells. It is suggested that there are adaptive responses at the level of chromosome and micronuclei to UV and EMS in CHO cells.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.73-81
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• 2017

The UV/chlorine process is a UV-based advanced oxidation process for removing various organic pollutants in water. The process is becoming increasingly popular because of its effectiveness in practice. It is important to the safe and efficient operation of a UV/chlorine process that the optimal operating conditions for both target removal objective and saving energy are determined. Treatment efficiency of target compounds in UV/chlorine process was mainly affected by pH and scavenging factor. In this study, kinetic based mathematical model considering water characteristics and electrical energy dose calculations model was developed to predict of treatment efficiency and optimal operating conditions. The model equation was validated for the UV/chlorine process at the laboratory scale and in pilot tests at water treatment plants.

• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.267-273
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• 2005

Dye wastewater generally contains strong color and non-biodegradable materials. Therefore, the conventional wastewater treatment plant can hardly meet the regulation of wastewater effluent water. In this study, a pilot plant of the conventional process followed by advanced oxidation process (AOP), was set up to treat the dying wastewater. The treatment efficiencies on the various candidate processes, such as ozone alone, UV alone, ozone/UV, $ozone/H_2O_2$, $H_2O_2/UV$ and $ozone/UV/H_2O_2$, were investigated in the various ozone and $H_2O_2$ doses. As the results, the $ozone/H_2O_2$ process, among the tested processes, showed the highest efficiency for removing color and $COD_{Cr}$. For color removal, the ozone alone process was enough without combining UV or $H_2O_2$. No significantly enhanced efficiency for removing color and $COD_{Cr}$ by UV irradiation was observed because of the very low transmittance of UV light in dye wastewater.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.902-910
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• 2012

The photodegradation characteristics of 30 pharmaceuticals were investigated by batch experiments using Ultraviolet (UV) reactor. The investigated pharmaceuticals include antibiotics, analgesics and antiarrhythmic agents etc. Tested water was prepared by simultaneously spiking 30 pharmaceuticals into pure water, and each experiment was conducted using 3 types of UV lamps. As a result, batch experiments showed that reactions of all the investigated pharmaceuticals followed pseudo-first order reaction regardless of the applied UV lamps. Among the pharmaceuticals, Cyclophosphamide, 2-Quinoxaline carboxylic acid and Clarithromycin proved to be the most UV-resistant compounds. Contrarily, Ceftiofur, Diclofenac and Ketoprofen were easily degraded by all the UV lamps. Dissolved organic carbon (DOC) concentration hardly changed although the concentration of the pharmaceuticals concentration gradually decreased with time, indicating that the degradation of parent pharmaceuticals may produce their intermediates during UV treatment.

• Environmental Engineering Research
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• v.11 no.2
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• pp.84-90
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• 2006

UV-catalytic oxidation technique was applied for the treatment of bio-refractory character of the leachate, which is generally present in the form of adsorbable organic halogens (AOX). Destruction of AOX was likely to be governed by pH adjustment, quantitative measurement of oxidants, and the selection of oxidation model type. Peroxide induced degradation ($UV/H_2O_2$) facilitated the chemical oxidation of organic halides in acidic medium, however, the system showed least AOX removal efficiency than the other two systems. Increased dosage of hydrogen peroxide (from 0.5 time to 1.0 time concentration) even did not contribute to a significant increase in the removal rate of AOX. In ozone induced degradation system ($UV/O_3$), alkaline medium (pH 10) favored the removal of AOX and the removal rate was found 11% higher than the rate at pH 3. Since efficiency of the $UV/O_3$ increases with the increase of pH, therefore, more OH-radicals were available for the destruction of organic halides. UV-light with the combination of both ozone and hydrogen peroxide ($UV/H_2O_2$ 0.5 time/$O_3$ 25 mg/min) showed the highest removal rate of AOX and the removal efficiency was found 26% higher than the removal efficiency of $UV/O_3$. The system $UV/H2O_2/O_3$ got the economic preference over the other two systems since lower dose of hydrogen peroxide and relatively shorter reaction time were found enough to get the highest AOX removal rate.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.5
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• pp.321-327
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• 2022

In this paper, a wrinkled structure was formed on the PDMS surface through UV/Ozone treatment, and the wrinkle structure formation mechanism was revealed through physicochemical characterization. A wrinkle structure was formed on the PDMS surface through UV/Ozone treatment for 30 min, and periodic wrinkle formation on the PDMS surface was confirmed by cross-sectional imaging of the scanning electron microscope. In addition, through x-ray photoelectron spectroscopy spectral analysis, it was confirmed that the silica-like-surface of SiOx on the PDMS surface was formed by UV/Ozone. The results of this study not only improve the understanding of the mechanism of wrinkle structure formation on the PDMS surface by UV/Ozone treatment, but also can be used as a basic study to adjust the amplitude and period of the wrinkle structure according to UV/Ozone irradiation conditions in the future.contact angles and the surface energies of FSAMs, it was confirmed that pretilt angles of LC molecules increased according to the alkyl chain length. High optical transparency and uniform homeotropic LC alignment characteristics of FSAMs showed the possibility of FSAMs as an LC alignment layers.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.580-584
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• 2010

As water becomes more scarce around the world the reuse of treated wastewater is being recenlty considered as indispensible trend we need to follow. Especially, industrial area consuming large amount of water has been encouraged to reuse the treated wastewater to secure sufficient water for the production of merchandise. In this study, a study of advanced oxidation process for treatment of industrial wastewater. The treatment performance of UV and ozoznation and five types advanced oxidation processes such as UV/AC, UV/Catalyst, $O_3$/Catalyst, UV/$O_3$/Catalyst was experimentally investigated for reuse of industrial wastewater. The removal efficiency of $COD_{Cr}$, color were relatively evaluated in each treatment unit simulated outflow water of wastewater treatment area. UV/$O_3$/Catalyst process showed the highest $COD_{Cr}$ remaval and color remaval among proposed oxidation process.

• Journal of the Semiconductor & Display Technology
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• v.16 no.2
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• pp.66-69
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• 2017

In this paper, solution based Indium Zinc Oxide thin film transistors (IZO TFTs) were fabricated with PVP gate dielectric. To enhance the electrical properties, UV-O3 treatment is proposed on solution based IZO TFTs. The gate leakage current and interface trap density is compatible with conventional ZnO-based TFT with inorganic gate insulator. Especially, the UV-treated device shows improved electrical characteristics compared to the untreated device. These results can be explained by X-ray photoelectron spectroscopy (XPS) analysis, which shows that the oxygen vacancy of UV-O3 treatment is higher than that of no treatment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.321-327
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• 2006

This study was performed to provide basic information for evaluating the efficiency and applicable extent of photocatalysis for the treatment of swine wastewater. Acid area was more efficient than neutral and alkalic areas in wastewater treatment, and level of pH3 was the most effective and the treatment efficiency continually increased as the amount of photocatalyst was increased. When the photocatalyst was increased, $TCOD_{Mn}$ was removed faster than chromaticity. Pollutants were more effectively eliminated with both UV light illumination and $TiO_2$ than with either UV or $TiO_2$ alone. The removal efficiency was increased with the addition of $H_2O_2$ as an oxidant, but the removal efficiency was decreased with over an dosage of $H_2O_2$. The optimal dosage of $H_2O_2$ was 200 mg/L. Continuous injection of $H_2O_2$ was required for effective oxidation.

• Journal of Sensor Science and Technology
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• v.25 no.4
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• pp.252-256
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• 2016

Epitaxially grown GaN layers have a high surface state density, which typically results in a surface leakage current and a photoresponse in undesirable wavelengths in GaN optoelectronic devices. Surface passivation is, therefore, an important process necessary to prevent performance degradation of GaN UV photodetectors. In this study, we propose oxygen-enhanced thermal treatment as a simple surface passivation process without capping layers. The GaN UV photodetector fabricated using a thermal annealing process exhibits improved electrical and photoresponsive characteristics such as a reduced dark current and an enhanced photoresponsive current and UV-to-visible rejection ratio. The results of this study show that the proposed surface passivation method would be useful to enhance the reliability of GaN-based optoelectronic devices.