• Bulletin of the Korean Space Science Society
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• 1993.10a
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• pp.11-11
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• 1993

The Korean sounding rockets(KSR) 1, 2 equigped with the UV optical detectors have been launched at An-heung, Chungchongnam-do, of June 4 and September 1, 1993,respectively. The UV detector is used to measure the attenuation of solar UV radiation for various frequency bards in the stratospgere. We obtained the profile of the ozone number density within the altitulde of 15 - 30 km by applying the Beer-Lambert law. It is found that the maHimum of the ozone distribution occurs near 2sht which is quite consistent with the mean value in the mid-latituderegions. We will also compare our results froiu KSR 1,2 with the other observational data from the Dobson speceo meter at Yonsei Univ. and the LIDAa which were performed simultaneously with the sounding rocket experiments.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.682-689
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• 2008

The purpose of this study was to find out the variation between molecular size distribution (MSD) of natural organic matter (NOM) in raw waters after different water treatment processes like conventional process (coagulation, flocculation, filtration) followed by advanced oxidation process (ozonation, GAC adsorption). The MSD of NOM of Suji pilot plant were determined by Liquid Chromatography-Organic Carbon Detection (LC-OCD) which is a kine of high-performance size-exclusion chromatography (HPSEC) with nondispersive infrared (NDIR) detector and $UV_{254}$ detector. Five distinct fractions were generally separated from water samples with the Toyopearl HW-50S column, using 28 mmol phosphate buffer at pH 6.58 as an eluent. Large and intermediate humic fractions were the most dominant fractions in surface water. High molecular weight (HMW) matter was clearly easier to remove in coagulation and clarification than low molecular weight (LMW) matter. Water treatment processes removed the two largest fractions almost completely shifting the MSD towards smaller molecular size in DW. No more distinct variation of MSD was observed by ozone process after sand filtration but the SUVA value were obviously reduced during increase of the ozone doses. UVD results and HS-Diagram demonstrate that ozone induce not the variation of molecular size of humic substance but change the bond structure from aromatic rings or double bonds to single bond. Granular activated carbon (GAC) filtration removed 8~9% of organic compounds and showed better adsorption property for small MSD than large one.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.795-798
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• 2003

Toxic organics are of great environmental concern primarily because they are toxic to mammals and birds, and are relatively soluble in water to contaminate surface water and groundwater. In this study, the decomposition of phenol, a widely used organic, in aqueous solutions by Boron doped diamond(BDD) electrode was examined. Thin, Boron-doped conducting diamond films are expected to be excellent electrodes for industrial electrolysis. Boron-doped diamond (BDD) were used as anode for generating ozone gas by electrolysis of acid solution. In this work. we have studied ozone generating system using BDD electrode. In order to determine the ozone generation properties of diamond electrode, experimental conditions, electrolyte concentration, temperature, flow rate and reaction time were varied diversely. As a result, we could confirm that ozone gas was generated successfully and the performance of diamond electrode was stable for electrolyte while $PbO_2$ electrode was disintegrated. Actually we are found that ozone amount increased by lowering the temperature of electrolyte. Decomposition of phenol concentration in the reaction solution by photolytic ozonation( $UV/O_3$) was analyzed by HPLC epuipped with a UV detector.

• Journal of Astronomy and Space Sciences
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• v.11 no.1
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• pp.53-70
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• 1994

The Korean sounding rockets(KSR420S-1, -2) equipped with ozone detectors have b3en launched at An-heung, Chungchungnam-do, on June 4 and September 1, 1993, respectively. The ozone detector is used to measure the attenuation of solar UV radiation for various frequency bands in the stratosphere, to obtain vertical profiles of the ozone number density in the stratosphere. They confirm that the maximum ozone densities occur near 25 km, which is quite consistent with the mean value in the mid-latitude region. Our results from KSR420S-1 and -2 are compared with the other observation data from the Dobson spectrophotometer at Yonsei Univ., the LIDAR at Kyunghee Univ., the SBUV from Nimbus satellite, and the TOVS from NOAA satellite, which were performed simultaneously with the sounding rocket experiments.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.244-249
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• 2018

Objectives: The purpose of this study was the investigation of bromide and bromate in drinking water of water supply plants, mineral springs and small water supply system located in northern area of Gyeonggi province. Methods: Analytical method was based on EPA 326.0 to use Postcolumn reaction (PCR). The instrument was 887 professional UV/VIS detector IC manufactured in Metrohm. Results: Bromate was detected at $0.5{\sim}2.4{\mu}g/L$ in tap water from 5 water supply plants. These plants were used as disinfection method for sodium hypochlorite and on-site chlorine that causes generate bromate as a by products even if not used ozone. Conclusions: The bromate was detected up to $2.5{\mu}g/Lin$ drinking water in northern Gyeonggi area that showed within $10{\mu}g/L$ for standard of tap water. However, the continuous monitoring of bromate is necessary in drinking water.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.63-71
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• 2006

An automated carbonyl measurement system was constructed. Atmospheric carbonyl compounds were extracted onto DNPH containing collection solution while flowing through a glass coil. Each carbonyl species was separated on a HPLC column and quantified by UV absorption detector. Using this system, carbonyl compounds were continuously measured at the campus of Korea University in Seoul, Korea during June, 2005. Sampling resolution was 30 minutes and the detection limit of HCHO was 0.19 ppbv. Also, $\O_{3}$, it's precursors, and meteorological parameters were measured. The maximum, minimum, average, and median concentrations of HCHO during the whole experiment was 35.8 ppbv, 1.4 ppbv, 11.7 ppbv, and 9.3 ppbv respectively. Formaldehyde showed a distinct diurnal variation with a broad maximum around 13 $\sim$ 15, which was 1 $\sim$ 3 hours ahead of an ozone maximum. During a couple of days, however, HCHO concentrations were kept high through the night or increased concomitantly with NOx in the morning. These results imply that HCHO was mainly produced from the photochemical oxidation of VOCs, but local emission sources couldn't be ruled out. The differences between daily maximum and minimum of $O_{3}$ and HCHO were calculated for 11 days of June, when typical diurnal variations were observed for the two species. A strong positive correlation was found between $\Delta O_{3}$ and $\Delta HCHO$ and the average mole ratio of $\Delta HCHO$ to $\Delta O_{3}$ was 2.6. It indicates that formaldehyde played a key role in $\Delta O_{3}$ production as an indicator species in Metropolitan Seoul during June, 2005.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.5
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• pp.227-231
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• 2005

We have developed a microsystem with a capillary electrophoresis (CE) and an electrochemical detector (ECD). The microfabricated CE-ECD systems are adequate for a disposable type and the characteristics are optimized for an application to the electrochemical detection. The system was realized with polydimethylsiloxane (PDMS)-glass chip and indium tin oxide electrode. The injection and separation channels (80 um wide$\ast$40 um deep) were produced by moulding a PDMS against a microfabricated master with relatively simple and inexpensive methods. A CE-ECD systems were fabricated on the same substrate with the same fabrication procedure. The surface of PDMS layer and ITO-coated glass layer was treated with UV-Ozone to improve bonding strength and to enhance the effect of electroosmotic flow. For comparing the performance of the ITO electrodes with the gold electrodes, gold electrode microchip was fabricated with the same dimension. The running buffer was prepared by 10 mM 2-(N-morpholino)ethanesulfonic acid (MES) titrated to PH 6.5 using 0.1 N NaOH. We measured olectropherograms for the testing analytes consisted of catechol and dopamine with the different concentrations of 1 mM and 0.1 mM, respectively. The measured current peaks of dopamine and catechol are proportional to their concentrations. For comparing the performance of the ITO electrodes with the gold electrodes, electropherograms was measured for CE-ECD device with gold electrodes under the same conditions. Except for the base current level, the performances including sensitivity, stability, and resolution of CE-ECD microchip with ITO electrode are almost the same compared with gold electrode CE-ECD device. The disposable CE/ECD system showed similar results with the previously reported expensive system in the limit of detection and peak skew. When we are using disposable microchips, it is possible to avoid polishing electrode and reconditioning.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.53-68
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• 1992

In order to research the adsorption removal characteristics of trace organic by-products in disinfection of drinking water by biological activated carbon(BAC), water samples disinfect- ted with $Cl_2$, $O_3$ and $ClO_2$ after treatment by fluidized-bed system with water added with humic acid(10mg/L) were investigated the formation and the removal of trihalomethanes (THMs), and the trace organic by-products by gas chromatography(GC) II gas chromatography/mass selective detector(GC/MSD). Control was used by activated carbon(AC) and water added with humic acid(HA). The results were summarized as follow : The THMs removal effect of BAC by chlorination was in lower 90 % than that of control(HA), the sorts of oxidants formed by $Cl_2$ , $O_3$ and $ClO_2$ were that $O_3$ was very fewer than $Cl_2$ or $ClO_2$, and that $ClO_2$ was fewer than $Cl_2$. The trace organic by-products were esters and phthalates etc. Based on results above, it is concluded that BAC was appeared the more desirable adsorbtion-degradation removal characteristics than that of AC.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.689-697
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• 2005

Hydrogen peroxide is a reservoir of OH radical which is the powerful oxidant in the atmosphere. Therefore, the status of the oxidizing atmosphere could be reflected on the concentration of $H_{2}O_{2}$. In this study, the distribution of $H_{2}O_{2}$ was determined during the intensive aircraft measurements over the Yellow sea in March, December 2002, April, November 2003 and March, October 2004. Flights covered from $124^{circ}E\;to\;129^{circ}E\;and\;35^{circ}N\;to\;37^{circ}N$, and extending to 3,000 m. The flight patterns were set properly to assess the altitudinal and longitudinal distribution for $H_{2}O_{2}$. $H_{2}O_{2}$ was extracted onto aqueous solution using a continuously flowing glass coil and analyzed by a high performance liquid chromatography (HPLC) accompanied with a fluorescence detector using postcolumn enzyme derivatization. Mixing ratios of $O_{3},\;NO_{x}\;and\;SO_{2}$ were measured in real time by commercial analysis instruments. Along the heights, the maximum concentration of $H_{2}O_{2}$ appeared around 1,500 m then gradually decreased with increasing altitude. The vertical behavior of ozone showed the similar trend to $H_{2}O_{2}$. The mean mixing ratio of $NO_{x}$ was about 2 ppbv and not showed clear vertical distribution patterns. The mean value of was the same as $NO_{x}$ however $SO_{2}$ appeared extreme concentration in low altitude. $H_{2}O_{2}\;and\;O_{3}$ showed even longitudinal distribution however $NO_{x}$ mixing ratio in land ($127^{circ}E$) was much higher than over the sea. $SO_{2}$ rather decreased with increasing longitude. $H_{2}O_{2}$ was in inverse proportion to $NO_{x}$ in spring and summer and $SO_{2}$ in spring, which indicated its significant role to NO and $SO_{2}$ oxidation pathways.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.45-45
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• 2017

The Indian meal moth, Plodia interpunctella, is one of the most important pests of stored food in the food processing industry worldwide. To control the Indian meal moth, methyl bromide, phosphine, high carbon dioxide, sulfuryl fluoride and plant essential oil fumigation have been considered. However, these treatments have disadvantages. For example, depleting the ozone layer, showing resistance in insect, low control efficacy or need high cost for treatment. Chlorine dioxide ($ClO_2$) is strong disinfectant and insecticide. The gas caused a malfunction in enzymes. The oxidative stress induced by $ClO_2$ gas treatment damaged to a physiological system and all life stages of P. interpunctella. The gaseous $ClO_2$ is a convincing alternative to methyl bromide for controlling P. interpunctella. The gaseous $ClO_2$ was generated by a chlorine dioxide generator (PurgoFarm Co., Ltd., Hwasung, Korea). It generated highly pure $ClO_2$ gas and the gas blown out through a vent into a test chamber. Gas entry to the chamber was automatically controlled and monitored by a PortaSene II gas leak detector (Analytical Technology, Collegeville, PA, USA). The properly prepared eggs, larvae, pupae, and adults of P. interpunctella were used in this experiment. Data were analyzed using SAS 9.4. Percentage data were statistically analyzed after arcsine-root transformation. Analysis of variance was performed using general linear model, and means were separated by the least significant difference test at P < 0.05. Fumigation is an effective management technique for controlling all stages of P. interpunctella. We found that $ClO_2$ gas treatment directly effects on egg, larvae, pupae and adults of P. interpunctella. The gas treatment with proper concentration for over a day achieved 100 % mortality in all stages of P. interpunctella and short time treatment or low concentration gas treatment results showed that the egg hatchability, pupation rate, and adult emergency rate were lowered compare with untreated control. Also, abnormal pupae or adult rate were increased. Gaseous $ClO_2$ treatment induced insecticidal reactive oxygen species (ROS), and it resulted in fatal oxidative stress in P. interpunctella. Taken together, these results showed that exposure proper concentration and time of the gas control all stages of P. interpunctella by inducing fatal oxidative stress. Further studies will be required to apply the gas treatment under real-world condition and to understanding physiological reaction in P. interpunctella caused by oxidative stress.