• 한국환경과학회지
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• 제9권3호
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• pp.201-208
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• 2000

PCBs and DDE were determined in the soil samples and the Korean striped field mice, Apodemus agrarius, collected at six localities in Changwon and one locality in Gaduck Island from August 1997 to May 1998. The residual level of PCBs in soils, in which the concentrations of high chlorinated compounds were much higher than those of low chlorinated ones, was highest in the industrial area(IA) in Changwon(60.7 ng/g in average), whereas those of DDE in soils was highest in Gaduck Island(331.9 ng/g in average). However, the levels of each compound detected from soils in the respective remaining places were relatively low. The similar tendency as in the soils was observed in the mice, indicating that the concentration of pollutants in the mice could denote the status of pollution in the terrestrial environment. The composition of PCB congeners in the mice, however, was different from that of soils, but similar to those of other mammals. Moreover, the residual levels of PCBs and DDE in pregnant females from which fetuses were removed were lower than those of males and non-pregnant females. It suggests that these compounds accumulated in pregnant females might have been transferred to the fetuses through placenta as in other mammals. Judging from the above facts, it is suggested that the striped field mouse can be an useful biological index to evaluate the contamination in mammals inhabiting terrestrial environment.

• Elastomers and Composites
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• 제38권1호
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• pp.72-80
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• 2003

자동차 Oil cooler용 호스를 구성하는 고무재료의 내열 및 난연성을 향상시키기 위하여 인산 에스테르계 화합물을 내열 및 난연제로 하여 제조한 염소화 폴리에틸렌(CPE) 배합고무의 가황 특성, 물리적 성질, 내열성, 난연성 및 변량효과를 조사하였다. 호스용 고무재료는 기존의 ethyleneacrylate rubber(EAR)보다 화학적 내식성과 내한성이 우수하면서도 가격이 저렴한 CPE 고무재료를 사용하였으며, 난연제는 비할로겐 축합 인산 에스테르계인 N,N'-bis-(diphenylphosphoro) diaminohexane(BDPDH)를 합성하여 CPE 고무재료와 $0{\sim}30 phr$ 범위에서 혼련하였다. 배합고무시편의 경도, 인장강도, 신율, 인장응력 및 열적 특성을 측정한 결과, CPE 배합고무의 유동성, 난연성, 내열성이 향상되었음을 확인하였으며, 고무재료 규격을 초과하지 않는 범위 내에서 최대의 내열 및 난연 효과를 주는 BDPDH의 배합량은 20 phr로 나타났다.

• 상하수도학회지
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• 제12권1호
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• pp.88-95
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• 1998

The Electron/Hole Pair is generated when the Activation Energy produces by Ultraviolet Ray illumination to the Semiconductor. And $OH^-$ ion produces by Water Photo-Cleavage reacts with Positive Hole. As a result, OH Radical acting as strong oxidant is generated and then Photocatalytic Oxidation Reaction occurs. The Photocatalytic Oxidation can oxidize the chlorophenol to Chloride and Carbon Dioxide easier, safer and shorter than conventional Water Treatment Process With the same degree of chlorination, the $Cl^-$ ion at para (C4) position is most easily replaced by the OH radical. And then, the blocking effect of $OH^-$ ion between the $Cl^-$ ions and $Cl^-$ ions at symmetrical location is easily replaced by the OH radical. For mono-, di-, tri-chlorophenols, there is no obvious difference in decomposition rate, decomposition efficiency and completeness of the decomposition reaction except for 2,3-dichloropheno, 2,4,5-, 2,3,4-trichlorophenol. The decomposition efficiency is higher than 75% and completeness of the decomposition reaction is higher than 70%. Therefore, continuous flow photocatalytic reactor is promising process to remove the chlorinated aromatic compounds which is more toxic than non-chlorinated aromatic compound.

• 청정기술
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• 제7권3호
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• pp.195-202
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• 2001

본 연구에서는 미량의 유기 염소계 화합물이 함유된 수용액에 대해 가교된 PDMS 막을 이용하여 투과증발 실험을 수행하였다. 실험 결과 공급액의 조성에 따라 트리클로로에틸렌의 플럭스는 선형적으로 증가하였으며 물의 플럭스는 약간씩 증가하는 경향을 보였다. 트리클로로에틸렌과 테트라클로로에틸렌의 비교 실험으로 트리클로로에틸렌이 보다 높은 분리 효율을 보임을 알 수 있었다. 조업온도의 증가는 트리클로로에틸렌의 분리효율에 좋은 영향을 미치지 않았으나 공급액의 유속은 플럭스의 큰 증가를 가져왔다. 높은 가교 밀도는 막으로의 용해도와 확산도를 감소시킨다. 가교 밀도에 트리클로로에틸렌의 플럭스와 선택도는 감소하였으며 이는 고분자 사슬의 움직임과 확산도의 감소로 설명이 가능하다.

• 한국환경과학회지
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• 제26권11호
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• pp.1201-1208
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• 2017

Oxidative degradation of chlorinated ethenes was carried out using heat-activated persulfate. The activation rate of persulfate was dependent on the temperature and the activation reaction rate could be explained based on the Arrhenius equation. The activation energy of persulfate was 19.3 kcal/mol under the assumption that the reaction between the sulfate radical and tricholoroethene (TCE) is very fast. Activation could be achieved at a moderate temperature, so that the adverse effects due to high temperature in the soil environment were mitigated. The reaction rate of TCE was directly proportional to the concentration of persulfate, indicating that the remediation rate can be controlled by the concentration of the injected persulfate. The solution was acidized after the oxidation, and this was dependent on the oxidation temperature. The consumption rate of persulfate was high in the presence of the target organic, but the self-decomposition rate became very low as the target was completely removed.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.77-80
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• 2001

Groundwater, contaminated predominantly with aromatic compounds and chlorinated ethylene, could be biologically treated in a fluidized-bed reactor with immobilized cells. The decomposition efficiency for the aromatics was over 90% at the retention time of 2.5 h. The chlorinated ethylenes, especially trichloroethylene (TCE) and cis-dichloroethylene (DCE), could be decomposed only insufficiently. No anaerobic methane formation was observed for this groundwater even at a very low dissolved oxygen (DO) concentration of 0.75 mg/L. The variation of DO concentration resulted in an optimal value of 1.5 mg/L. The recycle of air waste could increase the utilization of oxygen. The amount of low boiling pollutants stripped out remained constant with the recycle, while for the higher boiling pollutants the stripping slightly increased. Using air instead of oxygen increases the flow rate of air waste, which is connected to a higher stripping of pollutants. In this investigation, the pollutant concentration in the air waste remained constant. The stripping of main pollutants did not exceed 0.3 %.

• 펄프종이기술
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• 제29권2호
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• pp.36-45
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• 1997

Newly bleaching sequence using oxygen, ozone and hydrogen peroxide has introduced to avoid pollution hazards from chlorinated organic compounds, because chlorine dioxide substitution bleaching was produced a little chlorinated organic substance. Oxygen-type chemicals replaced for chlorine has attracted much research attention. Bleachability of ozone was improved at low temperature and high pulp consistency. In third bleaching followed OZ bleaching, addition of O2 and NaBH4 in alkali extraction was effective than only alkali extraction. Bleachability of pulps in ozone bleaching(Z) was improved at higher consistency and lower temperature The addition O2 and NaBH4 in alkali extraction after OZ bleaching sequence improved brightness, when compared to those obtained by only alkaline extraction. Pulps bleached by ECF bleaching sequences such as OZEoD and OZEopD was obtained by 90% ISO brightness. The brightness of pulp bleached by TCF sequences with the ozone dosage of 1.6% was approached to target brightness (88~90%ISO). Pulps bleached Z stage combined bleaching sequence was reduced the viscosity to a little greater extent. However, physical properties of pulps was not great different compared to those bleached by conventional bleaching sequences. A pollution index of bleaching effluente by ozone combined bleaching sequences was lower than by conventional bleaching sequence, but somewhat higher than multistage bleaching sequences combined C/D stage.

• 한국대기환경학회지
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• 제18권2호
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• pp.149-159
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• 2002

The objective of this study was to evaluate the formation characteristics of CBs and CPs from TCE, aliphatic compound. The experiment was carried out in a fixed reactor during 30 min under the oxidation condition at the range of temperature, 300~$700^{\circ}C$. MSWI fly ash was used as catalyst in this study. Total amount of CBs formed greater magnitude than that of CPs overall range of reaction temperature. It is proposed that the formation of CPs was caused from hydroxylation of CBs. According to increasing temperature to $600^{\circ}C$, the yield of CBs and CPs increased but significantly decreased at $700^{\circ}C$. It is suggested that decomposition rate was faster than formation rate at the high temperature. In the homologue distribution of CBs, DCBs were major products at 30$0^{\circ}C$ and the amount of higher chlorinated compound increased to $600^{\circ}C$. Because they were formed by chlorination of lower chlorinated compounds. In case of CPs, the amount of DCPs was 90% of total amounts in both thermal formation and catalytic reaction. On the other hand it was clearly observed that the chlorination rate in catalytic reaction was higher than in thermal formation with TCE only.

• 멤브레인
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• 제9권2호
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• pp.114-125
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• 1999

Poly(1-trimethylsilyl-1-propyne)(PTMSP), poly(dimethylsiloxane)(PDMS) 막 및 PTMSP-g-PDMS막 등의 균질 치밀막을 제조하여 chloroform, trichloroethylene(TCE), perchloroethylene (PCE) 등의 유기염소계 화합물에 대한 투과증발 분리성능을 평가한 결과 PCE 대해 가장 높은 선택성을 나타내었다. PTMSP 막들의 경우는 시간이 지나면서 투과특성이 현저히 감소하였으나 PTMSP-g-PDMS 막은 지속적인 투과특성을 나타내어 시간이 경과되어도 물리적 노화현상은 거의 없었다. 또한 접촉각 측정 결과 본 연구에 사용된 고분자막들은 모두 분리대상 용질에 대해 친화성을 보였으며 균질 치밀 막들에 대한 상대적 팽윤도가 클수록 신택도가 증가하였다.

• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.91-104
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• 2019

The taxonomic and functional characteristics of bacterial communities in the pre-chlorinated rapid filters and ozonated biological activated carbon (BAC) filters were compared using Illumina MiSeq sequencing of the 16S rRNA gene and community-level physiological profiling (CLPP) based on sole-carbon-source utilization patterns. Both the rapid filters and BAC filters were dominated by Rhizobiales within ${\alpha}-proteobacteria$, but other abundant orders and genera were significantly different in both types of filter. Firmicutes were abundant only in the intermediate chlorinated rapid filter, while Acidobacteria were abundant only in the BAC filters. Bacterial communities in the rapid filter showed high utilization of carbohydrates, while those in the BAC filters showed high utilization of polymers and carboxylic acids. These different characteristics of the bacterial communities could be related to the different substrates in the influents, filling materials, and residual disinfectants. Chlorination and ozonation inactivated the existing bacteria in the influent and formed different bacterial communities, which could be resistant to the oxidants and effectively utilize different substrates produced by the oxidant, including Phreatobacter in the rapid filters and Hyphomicrobium in the BAC filters. Bradyrhizobium and Leptothrix, which could utilize compounds adsorbed on the GAC, were abundant in the BAC filters. Ozonation increased taxonomic diversity but decreased functional diversity of the bacterial communities in the BAC filters. This study provides some new insights into the effects of oxidation processes and filling materials on the bacterial community structure in the biological filters of drinking water treatment plants.