• Journal of Environmental Science International
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• v.17 no.10
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• pp.1169-1182
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• 2008

The chemical and meteorological effects on the concentration variations of air pollutants ($O_3$ and its precursors) were evaluated based on ground observation data in coastal and inland regions, Busan during springs and summers of 2005-2006. For the purpose of this study, study areas were classified into 5 categories: coastal area (CA), industrial area (IA), downtown area (DA), residential area (RA), and suburban area (SA). Two sites of Dongsam (DS) and Yeonsan (YS) were selected for the comparison purpose between the coastal and inland regions. $O_3$ concentrations in CA and SA were observed to be highest during spring (e.g., 40 ppb), whereas those in DA and RA were relatively low during summer (e.g., $22\sim24$ ppb). It was found that $O_3$ concentrations in IA were not significantly high although high VOCs (especially toluene of about 40 ppb) and $NO_x$ ($\geq$ 35 ppb) were observed. On the other hand, the concentration levels of $O_3$ and $PM_{10}$ at the DS site were significantly higher than those at the YS site, but $NO_x$ was slightly lower than that at the YS site. This might be caused by the photochemical activity and meteorological conditions (e.g., sea-land breeze and atmospheric stagnance). When maximum $O_3$ (an index of photochemical activity) exceeds 100 ppb, the contribution of secondary $PM_{10}\;((PM_{10})_{SEC})$ to total observed $PM_{10}$ concentrations was estimated up to 32% and 17% at the DS and YS sites, respectively. In addition, the diurnal variations of $(PM_{10})_{SEC}$ at the DS site were similar to those of $O_3$ regardless of season, which suggests that they are mostly secondary $PM_{10}$ produced from photochemical reactions.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.66-71
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• 1998

A compact ESP of two-stage type is widely used with positive corona discharge in working environment where the production of ozone is extreamly prohibited. Since there are few scientific reports on a compact ESP, we have investigated the fundamental characteristics of a two-stage ESP. A model two-stage ESP is made with simple structure in order to simplify theoretical analysis and the relative position of the ionizer and collector section can be changed. The experimental investigation revealed many interesting facts.: The electric field in the collector electrodes affects the corona discharge of the ionizer. The concentration of particles after collector remarkably varied in the region between the high voltage and grounded electrodes. The collection efficiency right behind the high voltage electrode is much greater than that behind the grounded one. The total collection efficiency, calculated by integrating the particle concentration in whole measuring region, is greater when the high voltage electrode of the collector is located behind the discharge electrode of ionizer. Thus, the relative position of the ionizer and collector electrodes affects the precipitation characteristics.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.540-543
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• 2010

In this study, we made low temperature plasma reactor in order to treat safely $NO_x$ which included in the gas. We investigated experimently and inspected efficiency characteristics of equipment about flow rate of reactant material and discharge input power which supplied into reactor. As a reaction gas, by using mixture gas of $NO/N_2$ and $N_2/O_2$, we setted up initial NO concentration and supplied the speed of a current to 1~4 l/min. When the amount of flow increased, reduction rate of NO was low. Also when discharge input power was high, decomposition of NO was easy. Also the longer delay time of reaction material and the higher discharge input power was, the higher decomposition energy efficiency was. And when the amount of flow was much, and the more discharge input power increased, the more ozone generated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.779-786
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• 2008

This study was performed to evaluate the characteristics of current air quality and to examine the monthly and yearly variation of $SO_2,\;O_3,\;CO,\;NO_2$, and fine particulate matter(PM-10) concentration in Seosan for the period of 1998-2006. During the recent 3 years, from 2004 to 2006, the yearly mean concentration of $SO_2,\;NO_2$, and PM-10 remained stability but CO and $O_3$ are gradually decreased. The monthly mean concentration of $NO_2$, CO, and $SO_2$ were high in the winter season and decreased steadily to the summer season, but the maximum concentration of $O_3$ and PM-10 appeared in the springtime. The number of days exceeding 24-hour standards for PM-10 were 54 times at Dokgodri and 25 times at Dongmundong. The number of sampling days exceeding the 1-hour and 8-hour standards for $O_3$ were 68 and 210 times at Dongmundong and at Dokgotri 93 and 213 times, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.5
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• pp.536-546
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• 2016

The diurnal variations of $O_3$ and $NO_2$ in an urban park and the effects of air temperature and wind speed on the diurnal variations are investigated. $O_3$ and $NO_2$ concentrations were observed at a site in an urban park of Seoul from 27 July 2015 to 9 August 2015. The $O_3$ and $NO_2$ concentrations observed in the urban park are compared to those observed at the Gangnam air quality monitoring station (AQMS). The $O_3$ concentration is higher in the urban park than at the Gangnam AQMS in the daytime because the amount of $O_3$ dissociated by NO is smaller as well as partly because the amount of $O_3$ produced in the oxidation process of biogenic volatile organic compounds (VOCs) is larger in the urban park than at the Gangnam AQMS. The $NO_2$ concentration is lower in the urban park than at the Gangnam AQMS during day and night because the observation site in the urban park is relatively far from roads where $NO_x$ is freshly emitted from vehicles. The difference in $NO_2$ concentration is larger in the daytime than in the nighttime. To examine the effects of air temperature and wind speed on the diurnal variations of $O_3$ and $NO_2$, the observed $O_3$ and $NO_2$ concentrations are classified into high or low air temperature and high or low wind speed days. The high $O_3$ and $NO_2$ concentrations in the daytime appear for the high air temperature and low wind speed days. This is because the daytime photochemical processes are favorable when the air temperature is high and the wind speed is low. The scatter plots of the daytime maximum $O_3$ and minimum $NO_2$ concentrations versus the daytime averages of air temperature and wind speed show that the daytime maximum $O_3$ and minimum $NO_2$ concentrations tend to increase as the air temperature increases or the wind speed decreases. The daytime maximum $O_3$ concentration is more sensitive to the changes in air temperature and wind speed in the urban park than at the Gangnam AQMS.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.373-377
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• 2002

The Measurement of Pollution in the Troposphere (MOPITT) instrument is an eight-channel gas correlation radiometer launched on the Earth Observing System (EOS) Terra spacecraft in 1999. Its main objectives are to measure carbon monoxide (CO) and methane (CH4) concentrations in the troposphere. This work analyzes tropospheric carbon monoxide distributions using MOPITT data in East Asia and compared ozone distributions. In general, seasonal CO variations are characterized by a spring peak and decreased in the summer. Also, this work revealed that the seasonal cycles of CO are spring maximum and summer minimum with averaged concentrations ranging from 118ppbv to 170ppbv. The CO monthly means show a similar profiles to those of O3. This fact clearly indicates that the high concentration of CO in spring is caused by two possible causes: the photochemical CO production in the troposphere, transport of the CO in the northeast Asia. The CO and O3 seasonal cycles in northeast Asia are influenced extensively by the seasonal exchange of the different types of air mass due to the Asian monsoon. The continental air masses contain high concentrations of O3 and CO due to higher continental background concentrations and sometimes due to the contribution of regional pollution. In summer the transport pattern is reversed. The Pacific marine air masses prevail over Korea, so that the marine air masses bring low concentrations of CO and O3, which tend to give the apparent minimum in summer.

• Advances in environmental research
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• v.2 no.1
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• pp.1-8
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• 2013

There is a significant demand to make various dissolved gases in water. However, the conventional aeration method shows low gas mass transfer rate and gas utilization efficiency. In this study, a novel rotating wheel entraining gas method was developed for making high dissolved $O_2$ and $O_3$ in water. It produced higher concentration and higher transfer rate of dissolved $O_2$ and $O_3$ than conventional bubble aeration method, especially almost 100% of gas transfer efficiency was achieved for $O_3$ in enclosed reactor. For application of rotating wheel entraining gas method, aerobic bio-reactor and membrane bio-reactor (MBR) were successfully used for treatment of domestic and pharmaceutical wastewater, respectively; and vacuum ultraviolet $(VUV)/UV+O_3/O_2$ reactors were well used for sterilization in air/water, removal of dust particles and toxic gases in air, and degradation of pesticide residue and sterilization on fruits and vegetables.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.1
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• pp.97-103
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• 1995

This paper reports the following two topics : $\circled1$ ozone concentration (O$\sub$3con/) and discharge characteristics in flowing O$\sub$2/ with variation of Re$\sub$3/ at high voltage nozzle (HVN) of HVN 10 type ozonizer. $\circled2$ O$\sub$3con/ with variation of Re$\sub$3/ at HVN of HVN 25 type ozonizer. The important conclusions obtained from this paper are as follows. 1) In HVN 10 type ozonizer : $\circled1$ The discharge pattern can be controlled by adjustment of the Re$\sub$3/. $\circled2$ V$\sub$c/ is inversely proportional to pulse width (P$\sub$w/) and pulse frequency (P$\sub$f) $\circled3$ O$\sub$3con/ increase as decreasing of Re$\sub$3/ for constant P$\sub$w/ and P$\sub$f/. $\circled4$ O$\sub$3con/ increase as decreasing of P$\sub$w/, O$\sub$3con/ is proportional to P$\sub$f/. 2) In HVN 25 type ozonizer : O$\sub$3con/ of HVN 25 type ozonizer can increase than that of HVN 10 type ozonizer, according to parallel circuit of applied voltage and serial of supplied gas. As a result, we can obtain O$\sub$3con/ of 825[ppm] as the maximun value.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.493-498
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• 2002

$Al_2O_3$ is a promising gate dielectric because of its high dielectric constant, high resistivity and low leakage current. Since $OH^-$ radical in $Al_2O_3$ films deposited by ALD using TMA and $H_2O$ degrades the good properties of $Al_2O_3$, TMA and $O_3$ were used to deposite $Al_2O_3$ films and the effects of $O_3$ on the properties of the $Al_2O_3$ films were investigated. The growth rate of the $Al_2O_3$ film under the optimum condition was 0.85 $\AA$/cycle. According to the XPS analysis results the $OH^-$ concentration in the $Al_2O_3$ film deposited using $O_3$ is lower than that using $H_2O$. RBS analysis results indicate the chemical formula of the film is $Al_{2.2}O_{2.8}$. The carbon concentration in the film detected by AES is under 1 at%. SEM observation confirms that the step coverage of the $Al_2O_3$ film deposited by ALD using $O_3$ is nearly 100%.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1561-1569
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• 2013

This study carried out a laboratory scale plasma reactor about the characteristics of chemically oxidative species (${\cdot}OH$, $H_2O_2$ and $O_3$) produced in dielectric barrier discharge plasma. It was studied the influence of various parameters such as gas type, $1^{st}$ voltage, oxygen flow rate, electric conductivity and pH of solution for the generation of the oxidant. $H_2O_2$ and $O_3$.) $H_2O_2$ and $O_3$ was measured by direct assay using absorption spectrophotometry. OH radical was measured indirectly by measuring the degradation of the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical). The experimental results showed that the effect of influent gases on RNO degradation was ranked in the following order: oxygen > air >> argon. The optimum $1^{st}$ voltage for RNO degradation were 90 V. As the increased of $1^{st}$ voltage, generated $H_2O_2$ and $O_3$ concentration were increased. The intensity of the UV light emitted from oxygen-plasma discharge was lower than that of the sun light. The generated hydrogen peroxide concentration and ozone concentration was not high. Therefore it is suggested that the main mechanism of oxidation of the oxygen-plasma process is OH radical. The conductivity of the solution did not affected the generation of oxidative species. The higher pH, the lower $H_2O_2$ and $O_3$ generation were observed. However, RNO degradation was not varied with the change of the solution pH.