• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.543-548
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• 2006

This paper is to be researched into ozone generation character of Bi-Ti-Si type high dielectric ceramic catalyst discharge tube. And conditions of basic experiment are the outside diameter of discharge tube : 52 mm, the length of discharge tube : 350 mm, the frequence : 900 Hz, the temperature of cooling water : $25^{\circ}C$, quantity of flow : 5, 10, 20 L/min, pressure : 1.2, 1.4, 1.6 atm, and distance of discharge gap : 0.4, 0.6, 0.8 mm. Ozone generation characteristics were measured to consumption power. At quantity of flow : 20 L/min, discharge gap : 0.6 mm, pressure : 1.6, and consumption power : 150 W, Maximum ozone generation efficiency of 175 g/kWh was obtained. And a range of maximum ozone generation efficiency was measured below the flow quantity of 20 L/min at below pressure of 1.6 atm. However, Maximum ozone generation efficiency was measured over the flow quantity of 20 L/min at over pressure of 1.6 atm.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1998.10a
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• pp.1-1
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• 1998

Advanced (Chemical) oxidation processes (AOP) differ from most conventional ones in that hydroxyl radical(OH.) is considered to be the primary oxidant. Hydroxyl radicalcan react non-selectively with a great number of organic and inorganic chemicals. The typical rate constants of true hydroxyl radical reactions are in the range of between 109 to 1012 sec-1. Many processes are possible to generate hydroxyl radical. These include physical and chemical methods and their combinations. Physical means involves the use of high energy radiation such as gamma ray, electron beam, and acoustic wave. Under an applied high energy radiation, water molecules can be decomposed to yield hydroxyl radicals or aqueous electrons. Chemical means include the use of conventional oxidants such as hydrogen peroxide and ozone, two of the most efficient oxidants in the presence of promoter or catalyst. Hydrogen peroxide in the presence of a catalyst such as divalent iron ions can readily produce hydroxyl radicals. Ozone in the presence of specific chemical species such as OH- or hydrogen peroxide, can also generate hydroxyl radicals. Finally the combination of chemical and physical means can also yield hydroxyl radicals. Hydrogen peroxide in the presence of acoustic wave or ultra violet beam can generate hydroxyl radicals. The principles for hydroxyl radical generation will be discussed. Recent case studied of AOP for water treatment and other environmental of applications will be presented. These include the treatment of contaminated soils using electro-Fenton, lechate treatment with conventional Ponton, treatment of coal for sulfur removal using sonochemical and the treatment of groundwater with enhanced sonochemical processes.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.12
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• pp.567-572
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• 2002

In these days, diesel vehicle or power plant emits $NO_X\; and SO_2$ which cause air pollution like acid-rain, ozone layer destroy and optical smoke, therefore there are many kinds of methods considered for removing them such as SCR, catalyst, plasma process, and plasma-catalyst hybrid process. T$TiO_2$ is commonly used as catalyst to remove $NO_X$ gas because it have very excellent chemical characteristic as photo catalyst. In this paper, $NO_X$ sensing characteristic of $TiO_2$ thin film deposited by R.F Magnetron sputtering is investigated. A finger shaped electrode on $Al_2$O$_3$ substrate is designed and $TiO_2$ is deposited on the electrode by the magnetron sputtering deposition system. Chemical composition of the deposited $TiO_2$ thin film is $TiO_{1.9}$ by RBS analysis. When the UV is irradiated on it with flowing air, capacitance of $TiO_2$ thin film increases, however, when NO gas is put into the system with air, it immediately decreases because of photo chemical reaction. and it monotonously decreases with increasing NO concentration.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E3
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• pp.121-127
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• 2003

The characteristics of heterogeneous photocatalytic decomposition were investigated at low concentration level of $O_3$on TiO$_2$for various operating parameters such as: loaded catalyst weight (0∼4 mg/$\textrm{cm}^2$), initial concentration of $O_3$(0.06∼10.0 ppm), gas flow rate (1.0 ∼ 2.5ι/min), and relative humidity (0∼80%). This study was conducted using a flow-type reactor at room temperature. Three kinds of pure TiO$_2$(P25, ST -01, and E- 23) were employed as photocatalyts. It was found that $O_3$removal ratio was identical, regardless of the loaded TiO$_2$weight in the range from 0.5 to 4.0 mg/$\textrm{cm}^2$. It was also found that higher initial ozone concentration results in greater oxidation rate of ozone and experimental data show kinetically a good agreement with Langmur-Hinshelwood kinetic model. We also observed that the removal ratio of $O_3$increases linearly with the increasing flow rate and also with the increasing relative humidity for each catalyst.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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• pp.447-456
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• 2019

This study focused on natural organic matter and trihalomethane removal by ozonation with various ferrous concentration in surface water. Ozonation is more affected by injection concentration than reaction time. dissolved organic carbon removal rates in ozonation increased with the increase in ferrous concentration. The highest removal was obtained at 6 mg/L of ferrous concentration. When 1 mg/L of ferrous was added with 2 mg/L of ozone concentration, it was found to be a rapid decrease in specific ultraviolet absorbance at the beginning of the reaction because ferrous acts as a catalyst for producing hydroxyl radical in ozonation. As ozone concentration increased, trihalomethane formation potential decreased. When 2 mg/L of ozone was injected, trihalomethane formation potential was shown to decrease and then increase again with the increase in ferrous concentration.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.449-450
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• 1999

VOCs(volatile organic compounds)는 대기중에서 질소산화물과 함께 광화학반응에 참여하여 인체 및 동식물에 유해한 오존 등 2차 오염물질인 광화학산화물을 형성하는 전구물질로 작용한다. 1998년 8월 미국 EPA에서는 휘발성유기화합물과 지표 부근의 오존 또는 스모그의 발생량을 감소시키기 위해 페인트, 세제 및 살충제의 제조공법에 관한 새로운 규칙을 발표하여 휘발성 용제 사용 규제를 강호하고 있다(과학기술부, 1998).(중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.291-292
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• 2002

일반적으로 오존(O$_3$)은 친전자성 및 친핵성반응 때문에 탄소-탄소 이중결합을 가진 분자들을 떼어놓을 수 있는 매우 강한 산화능력을 갖고 있는 것으로서 살균, 맛과 냄새의 조절, 색도 제거 등에 이용되어왔다. 그러나, 오존은 대기 중에 미반응상태로 잔류하는 경우에는 광화학 스모그를 발생시키는 주된 요인이 되고 있으며, 강력한 산화력을 지니고 있기 때문에 0.1-l ppm의 범위에서 인체에 노출되면 두통, 목 건조증, 점막손상과 같은 호흡기 질환 등의 원인이 될 뿐만 아니라 악취를 유발하여 불쾌감을 야기한다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.173-174
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• 2002

실내 공기질은 재실자의 건강과 쾌적성 뿐만 아니라, 생산성 및 작업능률에도 영향을 미치며, 산업화와 자동차의 증가로 인한 대기오염은, 실내 공기질에 악영향을 미치고 있다. 또한, 에너지 절약을 위한 건물의 밀폐화와 환기율의 감소로 실내공기오염에 대한 관심도 증가되고 있다. 이는 결국, 보다 체계적이고 실용적인 공기정화 시스템의 필요로 이어지며, 그런 의미에서 현재 많은 상용 공기청정기에 대한 보다 효과적인 평가가 필요하다. (중략)

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1085-1089
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• 1998

The well-established nitric acid-sulfuric acid mixed acid process for the nitration of aromatic compounds has serious problems due to the large amount of waste acids and severe reaction conditions. Nitration of toluene can be conducted using nitrogen dioxide and ozone instead of mixed acid. We found that conc. nitric acid increased the reactivity as catalyst and the amount of nitrogen dioxide controlled the extent of nitration. Dinitration proceeded to more than 92 mole % conversion within 2 hr at $0^{\circ}C$ with 6 eq. of nitrogen dioxide and 2 eq./hr of ozone flow. Toluene completed mononitration within 30 min using 3 eq. of nitrogen dioxide, 3 eq. of nitric acid, and 1.5 eq./hr of ozone flow. As a clean process of aromatic nitration, this method is expected to replace the present process which causes the environmental problems.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.237-241
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• 2014

Benzene is a hazardous air pollutant, classified as carcinogenic to humans, that requires special management. Benzene exists both indoors and outdoors and the control measure of indoor benzene is different from that of outdoor benzene. The removal of indoor benzene needs to be accomplished at low temperatures (normally below $100^{\circ}C$), while outdoor benzene is usually removed at much higher temperature ($300-400^{\circ}C$) by using catalytic oxidation. This review paper summarizes the recent trend in catalytic treatment of airborne benzene, focusing on catalytic oxidation and catalytic ozone oxidation. Particular attention is paid to Mn-based catalysts for low-temperature oxidation of benzene, which are more economical than the other noble-metal catalysts. Various methods are used to generate more efficient Mn-based catalysts for benzene removal. Ozone oxidation is attracting particularly significant attention because it can remove benzene effectively below $100^{\circ}C$, even at room temperature.