• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.205-227
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• 2011

On this study, the test for air-purification was executed as using the UV lamp and the UV lamp on which the TiO2 catalyst had been deposited with glass fiber in the reactor chamber. It aimed at the basic data of air-purifier as assessing the features of removing abilities for various contaminants including CH3COOH, NH3, NO, and SO2 as varying the number of TiO2 coating, the wave of UV lamp, and the amount of additive CaO as variables.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.345-349
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• 2006

수용성 안료인 RhB를 대상으로 광-펜톤 공정의 최전 운전조건을 구하고, 광-펜톤 공정을 구성하는 개별 공정을 비교한 결과 다음의 결론을 얻었다. 광-펜톤 공정의 최적 $Fe^{2+}$와 $H_2O_2$ 투입량은 각각 0.0031 mmol과 0.625 mmol이었으며, 최적 pH는 3으로 나타났으나, 7이하의 pH 범위에서는 RhB 색 감소에 큰 영향을 미치지 않는 것으로 나타났다. 초기 반응 속도에 가장 큰 영향을 주는 인자는 UV 광 전력 > $H_2O_2$> 철염의 순으로 나타났다. 80분간의 반응시간 경과 후 최종 RhB 농도를 고찰한 결과 UV 광 전력이 낮을 경우 색도가 다 제거되지 않기 때문에 광-펜톤 공정에서 UV 광 전력이 색 제거에 대한 가장 큰 인자라고 사료되었다. 광-펜톤 공정의 개별 공정인 UV, $H_2O_2$, 펜톤을 이용하여 RhB의 농도감소를 고찰한 결과 초기 반응속도상수는 펜톤 공정의 빠른 초기 반응로 인해 펜톤 > UV >$H_2O_2$로 나타났으나, 최종 RhB 농도를 고려할 경우 UV> 펜톤 > $H_2O_2$로 나타났다.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.3039-3044
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• 2011

This study suggests the prediction model for the concentration variation of $NO_2{^-}$ and $NO_3{^-}$ along with the rate constants of all reactions during ozonation under UV radiation ($O_3$/UV process). While $NO_2{^-}$ was completely converted into $NO_3{^-}$ during the $O_3$-only process, the production of $NO_2$ radical or $N_2O_4$ was expected in the $O_3$/UV process. In addition, the quenching of OH radicals, by $NO_2$ radical in the $O_3$/UV process, resulted in regeneration of $NO_2{^-}$. However, the regeneration of $NO_2{^-}$ was not observed in the $O_3$/UV process in the presence of $C_6H_6$ where the concentrations of $NO_2{^-}$ and $NO_3{^-}$ were significantly reduced compared to in the process without $C_6H_6$. The pseudo-first order rate constants of all species were calculated with and without the presence of $C_6H_6$ to predict the variation of concentrations of all species during the $O_3$/UV process. It was suggested that $NO_2{^-}$ and $NO_3{^-}$ in the $O_3$/UV process can be more effectively removed from an aqueous system with an OH radical scavenger such as $C_6H_6$.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.293-301
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• 2008

A study on the operational variables of the UV-TiO$_2$ based photocatalytic air cleaning system was tried. In this study, to examine effects as various air cleaning system conditions, a duct-type reactor was made, and TiO$_2$ was immobilized on a stainless mesh. Benzene was chosen as a target compound. Removal experiments for benzene were done under different initial benzene concentration, air velocity, TiO$_2$ loading, area coated TiO$_2$ as the same TiO$_2$ loading, and UV light intensity conditions. During the experiments, relative humidity was 55%, and reactor temperature was 45$^{\circ}C$. As a result, the photocatalytic degradation of benzene decreased as the inlet concentration increased. But the photocatalytic degradation increased as the concentration boundary layer thickness, amount of TiO$_2$, area coated TiO$_2$ as the same amount of TiO$_2$, and UV light intensity increased. Based on results of current study, they can be applied to the design of air cleaning system over low level VOCs in the indoor air.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.731-738
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• 2011

In this study AOPs of $O_3/UV$ radiation, $O_3/Mg(OH)_2/UV$ radiation and $O_3/MgO/UV$ radiation system for phenol treatment in aqueous solution was performed in a laboratory scale circulating batch reacter. Flow rate of ozone 1.0 L/min, ozone concentrations $150{\pm}10mg/L$ was maintained constantly at the above-mentioned oxidation processes. During the oxidation processes the $COD_{Cr}$ and TOC was measured in the composition. The pseudo first-order rate constants of the processes was $5.12{\times}10^{-5}$, $1.19{\times}10^{-4}$ and $1.79{\times}10^{-4}sec^{-1}$, and the activation energy was 3.03, 1.79 and $2.32kcal{\cdot}mol^{-1}$ at $20^{\circ}C$, respectively. It was found that both $Mg(OH)_2$ and MgO had remarkable accelerations on degradation of phenol and removal of COD in water. On this basis, $O_3/MgO/UV$ system is an effective and feasible routes for catalytic ozonation of phenol in water.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1435-1447
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• 2012

The present study was conducted to determine the effect of hexaconazole (HEX), a triazole fungicide, on the growth, yield, photosynthetic response and antioxidant potential in cucumber (Cucumis sativus L.) plants subjected to UV-B stress. UV-B radiation and HEX were applied separately or in combination to cucumber seedlings. The growth parameters were significantly reduced under UV-B treatment, however, this growth inhibition was less in HEX treated plants. HEX caused noticeable changes in plant morphology such as reduced shoot length and leaf area, and increased leaf thickness. HEX was quite persistent in inhibiting shoot growth by causing a reduction in shoot fresh and dry weight. HEX noticeably recovered the UV-B induced inhibition of biomass production. Significant accumutation in anthocyanin and flavonoid pigments in the leaves occurred as a result of HEX or UV-B treatments. HEX permitted the survival of more green leaf tissue preventing chlorophyll content reduction and higher quantum yield for photosystemII under UV-B exposure. HEX treatment induced a transient rise in ABA levels in the leaves, and combined application of HEX and UV-B showed a significant enhancement of ABA content which activates $H_2O_2$ generation. UV-B exposure induced accumulation of $H_2O_2$ in the leaves, while HEX prevented UV-B induced increase in $H_2O_2$, indicating that HEX serves as an antioxidant agent able to scavenge $H_2O$ to protect cells from oxidative damage. An increase in the ascorbic acid was observed in the HEX treated cucumber leaves affecting many enzyme activities by removing $H_2O_2$ during photosynthetic processes. The activities of antioxidant enzymes including catalase(CAT), ascorbate peroxidase(APX), superoxide dismutase(SOD) and peroxidase(POD) in the leaves in the presence of HEX under UV-B stress were higher than those under UV-B stress alone. These findings suggest that HEX may participate in the enhanced tolerance to oxidative stress. From these results it can be concluded that HEX moderately ameliolate the effect of UV-B stress in cucumber by improving the components of antioxidant defense system.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.90-95
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• 2009

This study investigates the oxidative degradation of N-nitrosodimethylamine (NDMA), a probable human carcinogen, by advanced oxidation process (i.e., UV process). The experiments were performed with various pH, initial concentration, UV intensity, and addition of $H_2O_2$ or $TiO_2$ on UV process. The results showed that the direct UV photolysis was the most effective treatment method. The lower pH, intial concentration and higher intensity of UV stimulated higher NDMA removal. However, addition of oxidant ($H_2O_2$, $TiO_2$) slows down photochemical treatment of NDMA since the oxidant can filter out the UV light and block it to reach the NDMA molecules. Dimethylamine (DMA) and nitrite were found to be a major byproduct from NDMA oxidation. To evaluate the chronic toxicity effects of UV-treated NDMA on the growth of microalgae, "Skeletonema costatum", was studied as long term experiments. Results demonstrated that after the 13 days exposure the chronic toxicity was decreased about 15% with application of UV process on NDMA degradation.

• Food Science and Preservation
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• v.16 no.5
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• pp.636-643
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• 2009

Inactivation by UV-C irradiation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated onto washed carrots was examined. Carrot samples were inoculated with 6-7 log CFU/mL of E. coli O157:H7 or L. monocytogenes, treated with doses of 0, 1, 3, 5, or $10\;kJ/m^2$ UV-C, and stored at $4{\pm}1^{\circ}C$ for 8 d. The populations of E. coli O157:H7 and L. monocytogenes significantly decreased with increasing irradiation dose (p<0.05). In particular, E. coli O157:H7 and L. monocytogenes populations fell significantly by 2.35 and 2.38 log CFU/g at $10\;kJ/m^2$, respectively, compared to control values. UV-C irradiation inhibited color changes and decreased the whiteness index in carrot during storage, compared to controls. Sensory evaluation results showed that UV-C-treated carrots had better sensory characteristics than did the control. Therefore, the results suggest that UV-C irradiation could be useful to improve the microbial safety and sensory qualities of fresh-cut carrots during storage.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.452-457
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• 2008

분말 TiO$_2$를 코팅한 전극은 전기저항으로 인해 0.5 A 이상의 전류를 인가할 수 없었으며, 1 A를 적용하였을 때 60분의 반응시간 후 최종 RhB 농도를 측정한 결과 Ru/Ti 전극의 RhB 농도 감소 가장 큰 것으로 나타났고, Ru/Ti > Ti > SG-TiO$_2$ > Th-TiO$_2$로 나타났다. 전기분해 공정만 적용한 경우 RhB 농도 감소의 순서는 Ru/Ti = Ti > SG-TiO$_2$ > Th-TiO$_2$ 전극의 순서로 나타났다. UV만 적용한 경우 RhB 제거는 작았으며, Ti와 Ru/Ti 전극은 UV만 적용한 경우와 RhB 제거농도가 비슷하였는데 이는 전극 표면에서 광촉매 반응이 일어나지 않는다는 것을 의미한다. 반면 TiO$_2$를 전극 표면에 형성하거나 코팅한 전극은 UV만 적용한 경우보다 RhB 농도가 낮게 나타났고, TiO$_2$가 형성되거나 코팅된 전극은 P-TiO$_2$ > Th-TiO$_2$ > SG-TiO$_2$의 순서로 나타났으나 차이는 크지 않았다. 광전기촉매 공정에서 시너지 효과가 거의 없는 것은 전극 표면에 코팅되거나 형성된 TiO$_2$의 양이 적고 광촉매 반응에 의한 분해 정도가 낮아 전자-정공의 재결합 감소효과가 적기 때문인 것으로 사료되었다. Th-TiO$_2$와 SG-TiO$_2$ 전극의 경우 전해질로 Na$_2$SO$_4$를 사용한 경우의 RhB 농도가 NaCl을 사용한 경우보다 RhB 낮게 나타났으나, Ti와 Ru/Ti 전극의 경우는 반대 현상이 나타났다. 이와 같은 결과는 광촉매 반응이 높은 Th-TiO$_2$와 SG-TiO$_2$ 전극에서의 Cl$^-$의 광촉매 반응 저해현상이 높게 나타났기 때문이라고 사료되었다. 반면 DSA 전극인 Ti와 Ru/Ti 전극의 경우 광촉매 반응이 거의 나타나지 않기 때문에 주반응인 전기분해 반응에서의 촉진 반응이 지배적이기 때문에 Th-TiO$_2$와 SG-TiO$_2$ 전극과는 정 반대의 현상이 나타났다고 사료되었다. 전기/UV 공정에서는 최적 전류는 0.75 A, NaCl 투입량은 0.5 g/L로 나타났으며, 최적 UV램프 전력은 16 W인 것으로 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.726-732
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• 2007

We fabricated UV absorption functional $10{\sim}50nm-TiO_{2-x}/quartz$ structures layer using ALD (atomic layer deposition) method. We deposited $10nm-TiO_{2-x}$ layer on quartz substrate using ALD, and film thickness was determined by an ellipsometer. The others specimen thickness was controlled by ALD time lineally. We characterized controlling phase UV and visible optical property using an X-ray difractometer, a UV-VIS-IR spectrometer and a digital camera. $ALD-TiO_{2-x}$ layers were non-stoichiometric $TiO_{2-x}$ form and amorphous phases comparing with bulk $TiO_2$. While the conventional bulk $TiO_2$ had band gap of $3.0{\sim}3.2eV$ resulting in absorption edges at 380 nm and 415 nm, $ALD-TiO_{2-x}$ layers showed absorption edges at 197 nm and 250 nm. Therefore, our nano-thick $ALD-TiO_{2-x}$ was able to absorb shorter UV region and showed excellent transmittance in visible region. Our result implies that our newly proposed nano-thick $TiO_{2-x}$ using ALD process may improve transmittance in visible rays and be able to absorb shorter UV light effectively.