• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.497-504
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• 2000

To document that effects of hyperbaric oxygen(HBO) and ${\alpha}-tocopherol$ on full-thickness skin grafts in rat, we performed full-thickness skin grafts bilaterally on each rats. The HBO-treated rats were received HBO twice daily for 90 minutes at 2 ATA. Surgical control rats were not treated with HBO. ${\alpha}-tocopherol$ treated rats were received the agent via oral gastric tube daily for 3 days preoperative and a fourth dose 1 to 2 hours postoperative. HBO plus ${\alpha}-tocopherol$ treated rats were received HBO and ${\alpha}-tocopherol$ as mentioned above. Biopsy specimens were taken from each rat at the time of grafting and on days 2, 4, 7, 10, 14, 21, and 28, then were processed for tissue-concentration of total glutathione(GSHt), oxidized/reduced glutathione level, and thiobarbituric acid-reactive substance(TBARS) levels. The percentage of viable graft on day 10 ranged from 67 to 93%, and was not significantly different among the each other groups. The percentage of viable graft were, however, higher in HBO plus ${\alpha}-tocopherol$ treated rats(78.6%) than in HBO alone treated rats(59.1%), ${\alpha}-tocopherol$ alone treated rats(66.7%) and surgical control rats(58.2%). TBARS concentration had a significant increase from preoperative concentration at day 2, and peak concentration at day 4(p<0.01). Concentration then decreased to preoperative concentration at day 28. GSHt concentration of free skin graft had a similar patteren of change in four groups and decreased significantly from preoperative concentration at day 2, returning to preoperative concentration by day 7(surgical control, HBO-treated, and ${\alpha}-tocopherol-treated$, alone) and 28(HBO plus ${\alpha}-tocopherol-treated$). Percentage of the concentration of reduced glutathione decreased in surgical control, HBO-treated and, ${\alpha}-tocopherol-treated$(p<0.05), and HBO plus ${\alpha}-tocopherol-treared$(p<0.01) on day 7 after surgery, whereas the concentration of oxidized increased significantly in HBO-treated(p<0.05), ${\alpha}-tocopherol-treated$(p<0.05), and HBO plus ${\alpha}-tocopherol-treated$(p<0.01).

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E2
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• pp.107-120
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• 2002

Dimethyl sulfide (DMS) is the major sulfur gas released from the ocean. The atmospheric DMS released from the ocean is oxidized mainly by hydroxyl (OH) radical during the day and nitrate (NO$_3$) radical at night to form sulfur dioxide (SO$_2$) as well as other stable products. The oxidation mechanism of DMS via OH has been known to proceed by two channels; abstraction and addition channels. The major intermediate product of the addition channel has been known to be dimethylsulfoxide (DMSO) based on laboratory chamber studies and field experiments. However, a branching ratio for DMSO formation is still uncertain. The reaction of DMSO with OH ultimately produces SO$_2$and dimethylsulfone. The major product of the abstraction channel has known to be SO$_2$from laboratory chamber studies. But overall conversion efficiency for DMS to SO$_2$from DMS oxidation is still inconsistent in the literature. Based on laboratory and field studies, the conversion efficiency from the abstraction channel is likely to be greater than 0.5, while that from the addition channel is likely to be greater than 0.6. Overall conversion efficiency from DMS to SO$_2$might be greater than 0.5 based on the above two values in the remote marine boundary layer (MBL). This high efficiency in the remote MBL is supported by strong coupling between DMS and SO$_2$measurements with high temporal resolution.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.479-490
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• 2000

This study investigated the removal characteristics, Microcystin decomposition and generation of by-products when aqueous Microcystis sp. is oxidized by ozone. The concentration of Microcystin (MC) in aqueous solution has been found by HPLC analysis to decrease continuously by ozonation after the initial, abrupt increase. The kinetic constant of the decomposition of MC-RR and -LR were 0.0596 and 0.0243, respectively. This means that removal efficiency of MC-RR by its oxidative decomposition is preferable compared with that of MC-LR. On the other hand, it has been found that the decomposition product, TOC, exhibits the continuous decrease in the concentration by further ozonation, while DOC and UV-254 increase temporarily until 10 minutes before the decrease. Furthermore, the GC/MSD analysis has revealed that the ozonation of Microcystis sp. for 100minutes affords five kinds of aldehydes, six kinds of alcohols, and trans-1, 2-dimethyl-cyclopropane.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.195-196
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• 2009

This paper describes the fabrication and characteristics of polycrystalline 3C-SiC thin film diodes for extreme environment applications, in which the this thin film was deposited onto oxidized Si wafers by APCVD using HMDS In this work, the optimized growth temperature and HMDS flow rate were $1,100^{\circ}C$ and 8sccm, respectively. A Schottky diode with a Au, Al/poly 3C-SiC/$SiO_2$/Si(n-type) structure was fabricated and its threshold voltage ($V_d$), breakdown voltage, thickness of depletion layer, and doping concentration ($N_D$) values were measured as 0.84V, over 140V, 61nm, and $2.7{\times}10^{19}cm^2$, respectively. To produce good ohmic contact, Al/3C-SiC were annealed at 300, 400, and $500^{\circ}C$ for 30min under a vacuum of $5.0{\times}10^{-6}$Torr. The obtained p-n junction diode fabricated by poly 3C-SiC had similar characteristics to a single 3C-SiC p-n junction diode.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.73-76
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• 2002

Biofilter performance to reduce C $H_4$ emissions from MSW landfills was tested under a variety of environmental and design conditions. The optimum soil moisture content for C $H_4$ oxidation in a loamy sand was 13% by weight. The addition of N $O_3$-N did not affect the C $H_4$ oxidation rate. Soil depths of 30cm and 60cm were equally efficient in C $H_4$ oxidation. When the C $H_4$ loading rate was decreased, the percentage of C $H_4$ oxidized increased. The maximum C $H_4$ oxidation rate was 27.2 mol $m^{-2}$ $d^{-1}$ under optimum conditions (loamy sand soil, 13% moisture content, 30cm soil depth, and an loading rate of 32.8 mol $m^{-2}$ $d^{-1}$). Based on the above results, the installation of a properly sized and managed biofilter above a landfill cover should be capable of achieving a major reduction in atmospheric methane emissions from MSW landfills built with RCRA covers.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.25-31
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• 2013

Hydrogen peroxide takes much of the cost for Fenton reaction applied for treatment of organic contaminants. Therefore, the effective use of hydrogen peroxide makes the technology more cost effective. The effective use of hydrogen peroxide is especially needed in the soil and groundwater remediation where complete mixing is not possible and it takes a long time for reactive species to transport to the fixed target compounds. Stabilization ability for hydrogen peroxide of malonic acid was evaluated in Fenton and Fenton-like reactions in this study. Malonic acid contributes on the stabilization of hydrogen peroxide by weak interaction between iron and the stabilizer and inhibiting the catalytic role of iron. The stabilization effect increased as the solution pH decrease below the $pK_{a1}$. The stabilization effect increased as the concentration of malonic acid increased and the effect was maximized at the malonic acid concentration of about ten times higher than the iron concentration. The model organic contaminant was successfully oxidized in the presence of the stabilizer but the degradation rate was slower than the system without the stabilizer. The stabilization effect was also proved in a Fenton-like reaction where magnetite and hematite were used instead of soluble iron species.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.148-156
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• 2012

In this research, the application of carbon nanotubes (CNTs) modified PVDF (polyvinylidene fluoride) membrane was tested as a simply and beginning attempt to overcome membrane fouling because CNTs importantly affect the transport of natural organic matter (NOM). Suwannee River fulvic acid (SRFA) as the representative of NOM was selected and its sorption results with single-walled CNT (SWCNT), multi-walled CNT (MWCNT), and oxidized MWCNT (O-MWCNT) were obtained through the batch experiment. SRFA sorption isotherms had a strong nonlinearity and its sorption capacity followed the order O-MWCNT < MWCNT < SWCNT. The adsorbed mass of SRFA on each CNT decreased as a function of pH due to their charge repulsion. For the CNT-PVDF membrane filtration experiments, the suspended CNT solution (10 mg/40 mL) was incorporated into $0.45{\mu}m$-PVDF membrane and 5 mg/L of SRFA solution was monitored using UV detector connected with high pressure pump after passing through CNT-PVDF membrane. The SRFA removal efficiency by MWCNT-PVDF membrane was the strongest among other modified membranes. This suggests that the CNT modified microfiltration (MF) membrane might effectively and selectively apply to treat the contaminated water including organic compounds in the presence of NOM.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.6
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• pp.674-681
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• 2008

Silver as a metal catalyst has been used to remove odorous compounds. In this study, silver particles in nano sizes ($5{\sim}30nm$) were prepared on the surface of $NaHCO_3$, the supporting material, using a sputtering method. The silver nano-particles were dispersed by dissolving $Ag-NaHCO_3$ into water, and the dispersed silver nano-particles in the aqueous phase was applied to remove inorganic odor compounds, $NH_3$ and ${H_2}O$, in a scrubbing reactor. Since ammonia has high solubility, it was removed from the gas phase even by spraying water in the scrubber. However, the concentration of nitrate (${NO_3}^-$) ion increased only in the silver nano-particle solution, implying that the silver nano-particles oxidized ammonia. Hydrogen sulfide in the gas phase was rapidly removed by the silver nano-particles, and the concentration of sulfate (${SO_4}^{2-}$) ion increased with time due to the oxidation reaction by silver. As a result, the silver nano-particles in the aqueous solution can be successfully applied to remove odorous compounds without adding additional energy sources and producing any harmful byproducts.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.564-568
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• 2005

The structural change of azo dye (Acid Red 27) by oxidation with ozone has been investigated using FT-IR and $^1H$ NMR. The solution pH was observed to decrease during oxidation reaction, which was considered to be due to the generation of several organic and inorganic acids as the result of the decomposition of azo compound. The FT-IR analysis showed that changes of specific absorption bands of Acid Red 27 were observed after ozonation. When azo dye was oxidized by ozone, several new peaks were shown to appear by $^1H$ NMR analysis and the peaks were generally shifted to the direction of up field. This was presumably due to the breakage of benzene ring contained in the molecular structure of Acid Red 27 by the oxidation and the shape of peaks was shown to change according to the reaction time.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.653-657
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• 2014

Effects of $H_2O_2$ addition for fenton oxidation on iron coagulation for treatment of phosphorus species, such as orthophosphate, metaphosphate, pyrophosphate, organic phosphate, were investigated. The effects of coagulant dosage, hydrogen peroxide dosage and the combined sequence ferric coagulation and $H_2O_2$ addition for fenton oxidation and coagulation were studied. The characteristics of floc growth rate were monitored using the PDA. The removal efficiencies of phosphorus species by iron coagulation were increased as Fe/P molar ratio increased. However, the removal efficiencies of metaphosphate, pyrophosphate, organic phosphate by a ferric coagulation were not increased as Fe/P molar ratio increased. The removal efficiency of metaphosphate, pyrophosphate, organic phosphate was increased by using iron coagulation and $H_2O_2$ addition for fenton oxidation. The result indicated that non-reactive phosphorus after iron coagulation was changed to reactive phosphorus by $H_2O_2$ addition for fenton oxidation and the oxidized iron enhanced the coagulation efficiencies.