• 대한환경공학회지
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• 제32권9호
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• pp.894-899
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• 2010

슬러지 감량 효율을 높이기 위해 오존전처리와 고 액분리조를 이용한 이상 혐기성 소화 공정 통해 다음과 같은 결과를 얻었다. 오존전처리를 통한 슬러지의 고형물 농도는 평균 TSS $8.3{\pm}2.0%$, VSS $9.2{\pm}2.8%$의 감소율을 나타내었다. 유기물 농도인 TCOD는 평균 $5.1{\pm}2.4%$ 감소하는 반면 SCOD는 평균 $72.0{\pm}6.5%$ 증가하였는데, 이는 오존으로 인해 세포내의 고분자 유기물이 용출되어 가용화되었기 때문이다. 이상 혐기성 소화 공정의 반응조별 소화가 진행됨에 따라 평균 TSS $21.5{\pm}3.4%$, VSS $20.2{\pm}8.4%$, TCOD $32.1{\pm}7.9%$, SCOD $22.1{\pm}7.2%$의 농도가 감소하였다. 최대 메탄생성량은 177.6 mL $CH_4/g$ TSS, 210.8 mL $CH_4/g$ VSS, 127.0 mL $CH_4/g$ TCOD, 1452.0 mL $CH_4/g$ SCOD이었다. 이상 혐기성 소화와 MLE 하수처리 공정의 연계처리 후 고형물 물질수지 결과 TSS 93.8%, VSS 92.0%의 감소율을 보였다. 이상 혐기성 소화 공정은 슬러지 처리 문제 해결과 신 재생에너지인 바이오가스 회수의 가능성을 보여줌으로서 향후 슬러지 감량에 해결책이 될 수 있을 것으로 사료된다.

• 한국산업보건학회지
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• 제6권2호
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• pp.292-300
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• 1996

Hexavalent chromium($Cr^{+6}$) compounds are considered to be particularly hazardous, primarily because of the associated risk of allergic reaction and cancer. The analytic method of hexavalent chromium such as the s-diphenylcarba-zide(DPC) method and all ether previously used methods are often made uncertain due to significant interferences from organic components. This report can provide a technique for the more rapid and simple determination of total hexavalent chromium. than other currently using methods. The s-diphenylcarbazide method proposed by the U.S. National Institute for Occupational Safety and Health has low recovery rate(15.67 - 48.20%) due to interference, iron chloride and nickel chloride. A microwave oven technique has high recovery rate(about 70%) of insoluble hexavalent chromium. For the difference of ionic charges of $Cr^{+3}$-ethylenediamine tetraacetic acid(EDTA) chelate and $CrO_4{^{-2}}$, we could detect them simultaneously by ion exchanged high performance liquid chromatography. The confirmation of $Cr^{+3}$ and $Cr^{+6}$ were checked by fraction collector and flameless atomic absorption spectrometer. We observed that the small amount of hexavalent chromium is converted to trivalent chromium due to enhancement of chromium reduction by $Fe^{+3}$ or $Ni^{+2}$. As a result of this study, on the analysis of insoluble hexavalent chromium with microwave oven was used for, it may be better and more precise analysis after pretreatment by 2% NaOH-3% $Na_2CO_3$ and then analysis UV-spectrophotometer. It should be done for various studies on insoluble hexavalent chromium on the basis work environmental monitoring so called welding, painting etc.

• Journal of Microbiology and Biotechnology
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• 제18권4호
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• pp.735-741
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• 2008

In our previous study, a surfactant-coated Candida rugosa lipase immobilized in microemulsion-based organogels was exploited for the synthesis of ethyl isovalerate. In the present study, we are focusing on the effective reuse of lipase immobilized in microemulsion-based organogels (MBGs) in terms of retainment of the catalytic activity. As water is one of the co-products in esterification reactions, the removal of water becomes a priority to allow the reaction to work in the forward direction and to prevent back hydrolysis. Taking this fact into consideration, the lipase-containing microemulsion-based organogels were given pretreatment and/or several intermittent treatments with dry reverse micellar solution of AOT in organic solvent during repeated cycles of ester synthesis. The pretreated MBGs with dry reverse micellar solution exhibited lower water content and higher initial rates of esterification in comparison with untreated freshly prepared MBGs. The esterification efficiency of untreated MBGs started decreasing after 5 cycles of reuse and was almost completely lost by the end of the $8^{th}$ cycle. In contrast, pretreated MBGs exhibited a gradual decrease in esterification efficiency after 5 cycles and retained about 80% of the initial activity at the end of the $8^{th}$ cycle. The intermittent treatment of MBGs after every 3 cycles resulted in enhanced reusability of immobilized lipase for up to 9 cycles without significant loss in esterification activity, after which it resulted in a slow decrease in activity with about 27% lower activity at the end of the $12^{th}$ cycle. Furthermore, the treatment conditions such as concentration of AOT in liquid dessicant and time of treatment were optimized with respect to our system. The granulated MBGs proved to be better in terms of initial esterification rates (1.2-fold) as compared with the pelleted MBGs.

• 대한화학회지
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• 제39권7호
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• pp.513-523
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• 1995

다이옥신은 환경에 미량으로 존재하며 직접, 간접적인 경로를 통해 인체로 들어와 심각한 문제를 일으키는, 화학적으로 안정하고 잔류성과 독성이 강한 오염물질이다. 쓰레기 처리를 위한 소각로 시설은 다이옥신에 대한 대기오염의 주원인으로 알려져 있는데 연소시 소각로내에서와 배기가스 제어과정 중 다이옥신이 발생되는 것으로 보고되고 있다. 본 연구에서는 쓰레기 소각로에서 연소 후 생성된 바닥재 시료를 채취하여 다이옥신과 퓨란류를 조사하였다. 시료의 전처리는 EPA방법을 개선하여 불필요한 과정을 생략하면서 높은 회수율을 유지하였고 최종 정량은 고분해능 기체 크로마토그래피/고분해능 질량분석기(HRGC/HRMS)를 이용하여 분석하였다. 바닥재 시료를 분석한 전체 다이옥신의 양은 8.05 ng/g, 퓨란은 4.75 ng/g정도이었으며 2,3,7,8-TCDD는 6.93 pg/g이 검출되었고 염소원자 가 6~7개 치환된 다이옥신과 퓨란이 가장 많이 검출되는 경향을 볼 수 있었다.

• 한국화재소방학회논문지
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• 제33권6호
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• pp.80-86
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• 2019

국내에서는 2012년부터 2018년 까지 총 556건의 화학사고가 발생하였다. 화학사고 중 두 가지 이상의 화학물질 이상반응에 의해 발생하는 사고는 그 원인물질을 파악하는데 많은 시간이 필요하여 효과적인 사고대응과 수습을 위해서 신속한 분석이 필요하다. 본 논문은 이상반응에 의해 발생한 화학사고의 원인물질 파악을 위해 양자전이 비행시간 질량분석기를 사용하였다. 이 분석기는 시료채취와 전처리 없이 빠른 응답시간을 가져 실시간 분석이 가능하며 또한 수소친화도가 높은 대부분의 휘발성유기화합물질의 정량·정성 분석이 가능하여 이상반응에 의해 발생되는 화학사고의 원인 물질을 조사하는데 적합하다. 실제로 201◯년 ◯월에 ◯◯ 지역 화학사고 발생 시 양자전이 비행시간 질량분석기를 이용하여 측정한 결과 메탄올과 톨루엔 등이 검출되는 것을 알았으며 이상반응에 의해 발생된 황 계열 화합물이 사고 주변의 강한 악취의 원인임을 알 수 있었다.

• 대한전자공학회논문지TE
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• 제39권1호
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• pp.22-30
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• 2002

Si, SiO/sup 2/, TiN, W/sup 2/N 기판 위에 (hfac)Cu(VTMS) 유기금속 전구체로 증착된 구리 핵을 조사하였다. 증착온도가 증가함에 따라, 기판 종류에 상관없이 180。C에서 구리 핵이 클러스터링으로 성장하는 메커니즘을 관찰하였다. 또한, HF용액으로 세척한 TiN 과 SiO/sup 2/가 공존하는 기판에서 구리 핵의 선택성이 향상됨을 관찰하였다. TiN을 H/sup 2/O/sup 2/로 세척한 후 Dimethyldichlorosilane 처리했을 때 표면이 passivation됨을 확인하였다.

• Radiation Oncology Journal
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• 제13권1호
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• pp.87-94
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• 1995

Since March 1992, total 200 patients who visited our hospital as functional or organic lesions of central nervous system were treated by gamma knife stereotactic radiosurgery for 27 months. Thirty-nine patients of total cases was diagnosed as cerebral arteriovenous malformation. The rate of magnification on X-ray film was reduced by cutting fixation adaptor from 1.0 to below 1.45 times. In order to treat the deep- and lateral-seated cerebral arteriovenous malformation, we slightly modified the angiographic indicator, the commercial Leksell system, by cutting each inner sides about 5mm, We performed the more distinction of the scales by adapting 0.5mm or 1mm copper filter to angiographic indicator. The center point of indicator(X=100mm, Y=100mm, Z=100mm) is corrected by adjusting scales of X-, Y-, Z-axis to each inner 100 and outer 100 point within 1-2mm by repeated exposure of X-ray on films in trial-and-errors. We have developed the 'GKANGIO' programed as the Fortran-77 in Microvax - 3100, which can save treatment planning time and perform accurate pretreatment planning using the theoretical target metrix center. The theoretical description of the simplified method is presented for the reduction of experimental and numerical errors in treatment planning of radiosurgery.

• Applied Biological Chemistry
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• 제47권1호
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• pp.49-54
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• 2004

소톨론은 호로파(fenugreek)라는 콩과식물을 원료 물질로 하여 여러 가지 전환반응에 의해 생산될 수 있는 천연향미소재로서 본 연구에서는 생물 전환율을 높이기 위한 미생물이나 효소원을 탐색하였다. 원료로부터 소톨론을 추출하기 위한 유기용매로서 dichloromethane이 선별되었다. 효소원으로 사용될 수 있는 유산균, 효모, 사상균 등의 여러가지 미생물에 대한 스크리닝 결과 신령버섯(Agaricus blazei)이 높은 전환율을 보였다. 다양한 첨가물 및 전처리 조건에 따른 전환율을 조사한 결과 호로파 현탁액에 isoleucine, ${\alpha}-ketoglutaric$ acid, ascorbate, $FeSO_4$ 등의 첨가물을 첨가한 후 신령버섯의 균사체 배양액을 혼합하여 반응시키는 공정을 통하여 원료의 초기 소톨론 함량을 대략 77배 수준으로 높일 수 있었다.

• 한국유체기계학회 논문집
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• 제16권1호
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• pp.56-60
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• 2013

Non-conventional oil resources such as shale gas are becoming increasingly important and have drawn the attention of several major oil companies all over the world. Nevertheless, the market-changing growth of shale gas production in recent years has resulted in the emergence of environmental and water management challenges. This is because the water used in the hydraulic fracturing process contains large amount of pollutants including ions, organics, and particles. Accordingly, the treatment of this flowback water from shale gas plant is regarded as one of the key technologies. In this study, we examined the feasibility of membrane distillation as a treatment technology for the water from shale gas plants. Direct contact membrane distillation (DCMD) is a thermally-driven process based on a vaper pressure gradient across a hydrophobic membrane, allowing the treatment of feed waters containing high concentration of ions. Experiments were carried out put in the lab-scale under various conditions such as membrane types, temperature difference, flow rate and so on. Synthetic feed water was prepared and used based on the data from literature. The results indicated that DCMD is suitable for treating not only low-range flowback water but also high-range flowback water. Based on the theoretical calculation, DCMD could have over 80% of recovery. Nevertheless, organic pollutants such as oil and surfactant were identified as serious barriers for the application of MD. Further works will be required to develop the optimum pretreatment for this MD process.

• 한국환경성돌연변이발암원학회지
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• 제21권1호
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• pp.51-56
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• 2001

Kimchi is a major Korean traditional fermented food, as a supplying source of vitamin and minerals which is prepared with various vegetables and condiments such as red pepper, garlic and salted fish etc. There are many types of Kimchi depending on the ingredients and preparation methods used. To investigate the clastogenicity and anticlastogenicity of Baechu (Chinese cabbage) Kimchi and Buchu (leek, Allium odorum) Kimchi in mouse, it was performed acridine orange supravital staining of micronucleus (AOSS-MN) assay using mouse peripheral reticulocytes. Baechu Kimchi and Buchu Kimchi were cultivated by organic agricultural technique, and Kimchi samples were prepared by methanol extraction and lyophilization. First of all, it was studied the clastogenicity of two Kimchi samples themselves (250-1,000 mg/kg) after oral adminstration in mouse. And also to study the anticlastogenic effect of oral administration of Kimchi samples, mitomycin C (MMC, 1 mg/kg, i.p.) was used as micronucleus inducing agent in this study. Dosing scheme was performed as simultaneous (co-treatment), 3 hr before (pre-treatment) and 3 hr after (post-treatment) with MMC treatment. Two Kimchi samples in the range of 250-1,000 mg/kg did not reveal any clastogenic effect in AOSS-MN assay in mouse. They also revealed anticlastogenic effects in post-treatment of Baechu Kimchi (1,000 mg/kg), and in pre-treatment of Buchu Kimchi (500 and 1,000 mg/kg) with statistical significance. The anticlastogenic effect revealed 1 and 6 hr after treatment of Baechu Kimchi, and Buchu Kimchi with 3 and 6 hr pretreatment. Consequently, it is suggested that antimutagenic and anticlastogenic mechanisms of Baechu and Buchu Kimchi in vivo attributed to sipindle formation and kinetic behavior of mutagens such as absorption and metabolism etc.