• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.553-563
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• 2011

This study investigated the effects of elevated $CO_2$ and nitrogen addition on the anaerobic decomposition mediated by microorganisms to determine the microbial metabolic pathways in the degradation of organic matters of the sediments. There were statistically significant differences(P < 0.05) in the rates between denitrification and methanogenesis upon increased $CO_2$ concentration, nitrogen addition, in the presence of plants. Based on the assumption that anaerobic degradation of organic matter mainly occurs through denitrification, iron reduction, and methanogenesis, methanogenesis is the dominant pathways in the decomposition of organic matter under the condition of elevated $CO_2$ and nitrogen addition. In addition, the altered environment increased anaerobic carbon decomposition. Therefore, it can be concluded that freshwater wetland sediments have positive effects on the global warming by the increased methanogenesiss as well as increased anaerobic carbon decomposition.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.352-358
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• 2014

The feasibility of perchlorate reducing-bacteria isolated from the sludge of an anaerobic digester was determined using ammonium perchlorate in aqueous medium. Growth kinetics of the two perchlorate reducing bacteria including Rhodococcus sp. YSPW01 and YSPW02 were investigated using acetate as the electron donor in batch experiment. The growth of YSPW01 and YSPW02 reached a steady-state at 26 and 9 h, respectively. The initial perchlorate concentration was completely reduced within 8 and 7 h by YSPW01 and YSPW02, respectively. The reduction rates were 2.1 and $15mg\;L^{-1}h^{-1}$ for YSPW01, and 3.2 and $15.5mg\;L^{-1}h^{-1}$ for YSPW02, at 1:1 and 5:1 ratios of acetate:perchlorate (w:w), respectively. In this study, the bacteria Rhodococcus sp. YSPW01 and YSPW02 demonstrated a potential for the perchlorate reduction, which could be further investigated for development of an efficient strategy to treat the perchlorate contaminated waters.

• Transactions of the Korean hydrogen and new energy society
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• v.9 no.1
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• pp.8-15
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• 1998

The catalytic hydrogenation of carbon dioxide has been studied for the fixation of carbon dioxide to mitigate global warming problems, but it needed hydrogen, which the price is still high. Recently, the electrochemical reduction of carbon dioxide has been drawn attractions because carbon dioxide could be converted to the valuable chemicals such as methane, ethane and alcohols electrochemically in the electrolyte solution using a catalytic electrode. This system is simple because the water electrolysis and hydrogenation take place at the same time using the surplus electricity at midnight. In this work, a continuous electrochemical reduction system was fabricated, which was composed of the reduction electrode (copper or perovskite type, $2{\times}2cm^2$), reference electrode(platinum, $2{\times}6cm^2$), standard electrode(Ag/AgCl), and potassium bicarbonate electrolyte solution saturated with carbon dioxide. The quality and quantity of the products and reduction current were analyzed, according to the electrolyte concentration and electrode type.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.68-76
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• 2006

Anaerobic reductive dechlorination of tetrachloroethylene (PCE) to ethylene was investigated by performing laboratory experiments using semi-continuous flow two-in-series soil columns. The columns were packed with soils obtained from TCE-contaminated site in Korea. Site ground water containing lactate (as electron donor and/or carbon source) and PCE was pumped into the soil columns. During the first operation with a period of 50 days, injected mass ratio of lactate and PCE was 620:1 and incomplete reductive dechlorination of PCE to cis-DCE was observed in the columns. However, complete dechlorination of PCE to ethylene was observed when the mass ratio increased to 5,050:1 in the second operation, suggesting that the electron donor might be limited during the first operation period. Dechlorination rate of PCE to cis-DCE was $0.62{\sim}1.94\;{\mu}mol$ PCE/L pore volume/d and $2.76\;{\mu}mol$ cis-DCE/ L pore volume/d for that for cis-DCE to ethylene, resulting that net dechlorination rate in the system was 1.43 umol PCE/L pore volume/d. During the degradation of cis-DCE to ethylene, the concentration of hydrogen in column groundwater was $22{\sim}29\;mM$ and $10{\sim}64\;mM$ for the degradation of PCE to cis-DCE. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through in-situ biological anaerobic reductive dechlorination processes.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.52-58
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• 2005

In Korea, little attention has been paid to microbial perchloroethylene (PCE) and/or trichloroethylene (TCE) dechlorination activity and identification of microorganisms involved in PCE reductive dechlorination at a PCE-contaminated aquifer. We performed microcosm tests using the groundwater samples from 4 different contaminated sites (i.e. Changwon A, Changwon B, Bucheon and Yangsan) to assess PCE reductive dechlorination activity. We also adapted molecular techniques to screen what types of known reductive dechlorinators are present at the PCE-contaminated aquifers. In the Changwon A and Changwon B active microcosms where potential electron donors such as sodium propionate, sodium lactate, sodium butyrate, and sodium fumarate, were added, ethylene, an end-product of complete reductive dechlorination of PCE, was detected after a period of 90 days of incubation. In the Bucheon and Yangsan active microcosms, cis-1,2-dichloroethylene (c-DCE) was accumulated without the production of vinyl chloride (VC) and ethylene. Molecular techniques were used to evaluate the microbial community structures in the Changwon B and Yangsan aquifer. We found two sequence types that were closely related to a known PCE to ethylene dechlorinator, named uncultured bacterium clone DCE47, in the Changwon B site clone library. However, in the Yangsan site clone library, no sequence type was closely related to known PCE dechlorinators reported. It is plausible that microorganisms being capable of completely dechlorinating PCE to ethylene may be present in the Changwon B site aquifer. In this study we find that complete PCE reductive dechlorinators are present at some PCE-contaminated sites in Korea. In an engineering point of view this information makes it feasible to apply a biological reductive dechlorination process for remediating PCE- and/or TCE-contaminated aquifers in Korea.

• Journal of Digital Convergence
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• v.18 no.6
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• pp.435-441
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• 2020

This study attempts to analyze by the gender political point of view of the recent film, 'A Special Lady', focusing on the case of setting up women as the main characters in the 2000s Korean film noir genre. Concretely, this study conducted a narrative analysis focusing on the three elements of genre film, the identity of the characters and their family relationships, and the Oedipal trajectory. The film, 'A Special Lady', has the narrative about the maternal love assigned to female protagonist, and that emphasizes male pure love. And the film shows the flashbacks concerning to motherhood that prove the biological identity of the female protagonist, and signs that weaken the castration fear resulting from male voyeurism. Further, the film depicts the fragmentation of identity and the cracking of family relationships, revealing the confusion of gender identity and the narrative degeneration into family melodrama. Meanwhile, the film fails to complete the feminine Oedipal trajectory by reducing the female character's motherhood to a biological one instead of expanding it into an alternative quality embracing the other. These findings suggest that the korean gangster is closely related to gender politics and is not completely out of gender bias.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.675-680
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• 2013

This research was done to evaluate the potential for destruction of perchlorate in municipal sewage. Laboratory experiments were conducted in flasks containing 3 liters of raw sewage. Sewage was mixed with defined amount of perchlorate and various additives. Perchlorate reduction in sewage did occur, but was quite variable, ranging from 0 to 72% over 72 hour. Addition of even a small amount of perchlorate acclimated biomass (167 mg/L SS) significantly reduced the lag and resulted in complete perchlorate removal. Perchlorate reduction in sewage-brine mixtures was inhibited when the dissolved oxygen level was greater than 2 mg/L, and when the mixture salinity was relatively high (conductivity = 14 mS with equivalent TDS = 8 g/L). When nitrate ($NO_3{^-}$) was present with perchlorate in the laboratory flask tests of sewage-brine mixtures, nitrate reduction proceeded first. A significant amount of nitrite ($NO_2{^-}$) accumulated in the sewage-brine mixtures, accounting for about 66% of initial nitrate nitrogen ($NO_3$-N).

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.432-449
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• 2002

For various oxidoreductases, the optimum pHs of the enzymes can be calculated using the rule based on proton transfer. Relative probability of a certain amino acid side chain to be in the water, or the relative affinity to the water was calculated using Boltzman distribution. Also, the protonated and deprotonated portions of a certain amino acid side chain were calculated using p$K_R$ of that and the effective protonated and deprotonated protions were the product of relative probability and the protonated and deproteonated protions. Where the total effective protonated portion was equal to the effective deprotonated portion of amino acid side chains, it was expected that oxidoreductases have max-imum activities. The optimum pHs calculated by our rule were compared with the experimental results.

• Resources Recycling
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• v.16 no.6
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• pp.52-60
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• 2007

Denitrification from aqueous solution was investigated through patent analysis and electrochemical denitrification experiment. Among several candidates, biological treatment and oxidation/reduction method are mainly discussed. Recently, patent pending concerning to electrochemical treatment is increasing. Based on basic electrochemical study, total nitrogen was removed up 47% by 1-hour galvanostatic electrolysis with Fe cathode and Pt anode. More applicable technique to industry could be mentioned combination of two or more technologies suitable to waste water characteristics. In the case of small and concentrate effluent, combination of chemical and electrochemical treatment would be recommendable because nitrate could be easily converted to nitrite by chemical treatment, and in that case denitrification by electrolysis becomes more efficient and metal ions from chemical treatment can be recovered during electrolysis.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.164-168
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• 2012

We investigated for the production of biological bio-ethanol from Laminaria japonica using the hydrolysis reaction of enzymes and organic acids and the polysaccharide content was also analyzed. The composition of the polysaccharide was characterized as 65.99% alginate, 6.24% laminaran and 27.77% mannitol. The optimum concentration for reducing the sugar conversion by Laminaria japonica was found to be 1.874 g/L at an acetic acid concentration of 1.5%, $121^{\circ}C$ for 60 min, and for an ascorbic acid of 2.0%, 4.291 g/L was produced in the same condition. The enzyme hydrolysis such as alginate lyase and laminarinase contained the maximum 2.219 g/L reducing sugar. In the result of ethanol fermentation using hydrolysate of Laminaria japonica, the organic acid treatment showed a high of reducing sugar yield, but decreased the ethanol yield, and then the maximum ethanol production obtained was 1.26 g/L using the mixed treated of enzyme.