• 대한의생명과학회지
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• 제29권4호
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• pp.256-262
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• 2023

The purpose of this study is to investigate microbial contamination in water purifiers from two universities (A and B) in Chungcheong region and to evaluate about the harmfulness of the isolated bacteria to the human. The degree of microbiological contamination of six water purifiers at university A was investigated three times from July 2018 to September 2019, and nine water purifiers at university B were investigated in 2023. The isolated bacteria were biochemically identified using an API kit and Vitek-2 system, and then the bacteria were identified to the species level using MALDI-TOF MS. In addition, the possibility of human infection of the isolated bacteria was evaluated through a literature search. In July 2018 and September 2019, the number of bacteria isolated inside the faucet was below the acceptable standard for hot water, but exceed for cold water in all water purifiers. In January and September 2019, bacteria exceeding the acceptable standards were isolated nine times from the cold water of six water purifies (a total of 12 water purifiers). Bacteria identified by MALDI-TOF MS included anaerobic bacteria (Clostridium novyi, Clostridium themopalmarium etc.), Gram-positive bacilli (Microbacterium testaceum, Arthrobacter woluwensis etc.), and Gramnegative bacilli (Acinetobacter nosocomialis, Comamonas kerstersii etc.), which are difficult identify by biochemical methods. In conclusion, bacteria exceeding the acceptable standard were isolated from the cold water of most of the water purifiers. Most of the isolated bacteria were low-pathogenic bacteria from natural environment, but opportunistic bacteria that can cause infection in humans were also isolated from some water purifiers.

• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.128-133
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• 2013

Objectives: This study was performed to evaluate the effect of blood contamination on the compressive strength (CS) of Root MTA (RMTA) modified with Calcium chloride ($CaCl_2$) and Disodium hydrogen phosphate ($Na_2HPO_4$) as setting accelerators over time. Materials and Methods: A total of 110 cylindrical specimens of RMTA were divided into 6 experimental groups as follows: Group1, RMTA; Group 2, RMTA modified with $CaCl_2$ (RMTA-C); Group 3, RMTA modified with $Na_2HPO_4$ (RMTA-N); Group 4, RMTA contaminated with blood; Group 5, RMTA-C contaminated with blood; Group 6, RMTA-N contaminated with blood. The CS of specimens in all groups was evaluated after 3 hr, 24 hr, and 1 wk. In the modified groups (groups 2, 3, 5, and 6) the CS of five specimens per group was also evaluated after 1 hr. Results: Blood contamination significantly reduced the CS of all materials at all time intervals (p < 0.05). After 3 hr, the CS of specimens in the RMTA groups (with and without blood contamination) was significantly lower than those in the RMTA-C and RMTA-N groups (p < 0.05). The CS values were not significantly different at the other time intervals. In all groups, the CS of specimens significantly increased over time (p < 0.05). Conclusions: Blood contamination decreased the CS of both original and accelerated RMTA.

• 한국초전도ㆍ저온공학회논문지
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• 제21권2호
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• pp.31-35
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• 2019

Andong-dam was built up in 1967 and it is one of the biggest dams in Korea. Previous studies showed that the sediments are highly contaminated with heavy metals such as arsenic, cadmium, and lead. Many research projects are going on to find out the source of the contamination, to evaluate the toxicities to ecosystem, to estimate the volume of sediment to be treated and to find out a good remediation method. Reports show that the sediment is highly contaminated and the main contamination source is supposed to be abandoned mines and a zinc refinery located upper stream of the river. A magnetic separation has been tested as a treatment method for the dredged sediment. Lab scale test showed that the magnetically captured portion is about 10% in weight but the contamination of heavy metal is much higher than the contamination of the passed portion. This indicates that a magnetic separation could be applied for the purpose of reduction of sediment to be treated and for increasing the volume of low toxic sediments which can be dumped as general waste. A magnetic separation using a HGMS has been tested for the sediment with variable magnetic field and the results showed the higher magnetic field increase the captured portion but the concentrating effect of heavy metal was weakened. Further study is needed to establish a useful technology and optimization between decontamination and reduction of sediment volume.

• 한국식품영양학회지
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• 제33권6호
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• pp.702-709
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• 2020

The purpose of this study was to evaluate microbiological contamination of knives and cutting boards in child-care centers. Materials used in this study were swabbed of cutting boards and knives (blade, handle of knife, and joint of handle and blade) in 129 child-care centers. Mean values of total aerobic bacteria of swabs of knives and cutting boards were 1.7±0.7 log cfu/100 ㎠ and 1.7±0.9 log cfu/100 ㎠, respectively. Contamination levels of coliform bacteria from knives and cutting boards were 1.5±0.6 log cfu/100 ㎠ and 1.7±0.8 log cfu/100 ㎠, respectively. Comparing microbiological contamination levels of knives and cutting boards according to type and size of child-care centers, there was no significant difference. Bacillus cereus was detected in knife handles and cutting boards. Diarrhea-type toxin gene (entFM) was detected in B. cereus isolates. Antibiotic resistance tests showed that B. cereus was resistant to β-lactam antibiotics. To reduce microbiological contamination levels of knives and cutting boards in child-care centers and prevent food poisoning from bacteria contamination, continuous education by children's food-service management center is needed for sterilization and disinfection of knives and cutting boards.

• Journal of Microbiology and Biotechnology
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• 제31권12호
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• pp.1709-1715
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• 2021

Outbreaks of food poisoning due to the consumption of norovirus-contaminated shellfish continue to occur. Male-specific (F+) coliphage has been suggested as an indicator of viral species due to the association with animal and human wastes. Here, we compared two methods, the double agar overlay and the quantitative real-time PCR (RT-PCR)-based method, for evaluating the applicability of F+ coliphage-based detection technique in microbial contamination tracking of shellfish samples. The RT-PCR-based method showed 1.6-39 times higher coliphage PFU values from spiked shellfish samples, in relation to the double agar overlay method. These differences indicated that the RT-PCR-based technique can detect both intact viruses and non-particle-protected viral DNA/RNA, suggesting that the RT-PCR based method could be a more efficient tool for tracking microbial contamination in shellfish. However, the virome information on F+ coliphage-contaminated oyster samples revealed that the high specificity of the RT-PCR- based method has a limitation in microbial contamination tracking due to the genomic diversity of F+ coliphages. Further research on the development of appropriate primer sets for microbial contamination tracking is therefore necessary. This study provides preliminary insight that should be examined in the search for suitable microbial contamination tracking methods to control the sanitation of shellfish and related seawater.

• 한국유기농업학회지
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• 제23권4호
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• pp.659-682
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• 2015

This study was conducted to suggest ideal management system for organic materials. As the performing method of the study, surveyed results on understanding of related persons (organic farmer 846, organic materials manufacture 70 and Organic materials Auditors 7) with eco-friendly farming were used. And the opinion on unintentional pollution source contained in organic materials was surveyed additionally. The issues pointed out by organic farmers on product of organic materials were high price (60% to total), poor efficacy (16%), disorder on distribution system (13%) and containing chemicals as a pesticide (10%). And notification system for organic materials was accepted in general (positive and so so 76%) while most interviewees preferred (89%) unification of certification system dominantly. As unintentional contamination source, pollution on imported row material was indicated as major reason, and other causes were confirmed as insertion during manufacturing process, agricultural by-products using as product additive et al. Based on these surveyed results, authors suggest bellows as considerable methods for effective improvement of management system on organic material. First, establish new integrated certification system which contains standard of quality certification and notification system on organic material. Second, for evaluation of efficacy, apply relative evaluation system of significance such as Duncan's multiple test instead of existing absolute evaluation system. Third, constitute and operate selection of standard comparison subcommittee in organic Agro-materials committee in RDA.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.10-18
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• 2011

This study presents a state of the art in evaluation on naturally occurring asbestos (NOA) areas and effective strategies for investigation and management of NOA areas in Korea. First of all, we defined and classified the NOA area as compiling various countries' regulations, then discussed the best methods for evaluation and management of NOA for reducing exposure of asbestos in the vicinity of NOA areas. According to the literature survey, a three-steps management strategy was suggested in this study. The first step is a confirmation stage of asbestos contamination possibility and the second step is an assessment stage of asbestos contamination using investigation, analysis, evaluation and reclamation. The final step is a following-up control stage. These three management steps for NOA area will give the maximum effectiveness of NOA control in Korea.

• 농약과학회지
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• 제11권3호
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• pp.144-153
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• 2007

Groundwater ubiquity score(GUS)를 이용하여 제주도 농가에서 많이 사용되고 있는 농약에 대한 지하수 오염가능성을 평가하고 등급화 하였다. 살충제 12종, 제초제 6종, 살균제 3종을 선정하여 제주도 20개 토양통에 대한 흡착특성과 농약의 이화학적 특성을 이용하여 GUS를 구하였다. 제주도 토양에서 조사된 각종 농약의 전반적인 지하수 오염가능성은 제초제 > 살균제 > 살충제 순서이었다. 제초제의 지하수 오염가능성의 크기는 bromacil > metolachlor > alachlor > linuron pretilachlor > butachlor 순서로 나타났다. 살충제의 지하수 오염가능성의 크기는 carbofuran > ethoprophos > diazinone > dimethoate > penthoate > mecarbam > methidathion > endosulfan > fenitrothion > parathion > chlorpyrifos > terbufos 순서로 나타났다. 살균제의 지하수 오염가능성의 크기는 metalaxyl > chlorothalonil > triadimefon 순서로 나타났다. 이들 농약 중에서 특히 지하수 오염가능성이 높은 것으로 분류된 것은 제초제 alachlor, metolachlor, bromacil, 살충제 ethorophos와 carbofuran 그리고 살균제 metalaxyl이었다. 농약에 의한 지하수 오염을 방지하기 위해서는 농약의 절대 사용을 줄일 수 있는 방안을 마련함과 동시에 지하수 오염가능성이 낮고 오염시킨 예가 적은 약제의 선별적 사용이 바람직할 것이다. 그리고 특히 오염가능성이 매우 높은 것으로 평가되고 오염의 예가 많은 약제에 대해서는 적극적인 사용제한 방안을 마련할 필요도 있을 것이다.

• 정보처리학회논문지D
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• 제11D권1호
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• pp.31-38
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• 2004

본 논문은 지하수 관정의 안전성 평가를 위한 시스템을 구현하였다. 지하수의 수질은 지상오염 원인의 영향을 받으므로 수질 성분의 측정으로 영향의 원인과 그 정도를 파악할 수 있다. 본 논문은 지하수 관정과 영향을 주는 지리-객체의 공간관계성을 지리정보시스템의 포함(contain) 연산자와 거리(distance) 연산자를 사용하여 평가하는 방법을 제안하였다. 연구대상은 전라북도 군산 지역으로서 주로 제4기 충적층에 있는 75개의 지하수 관정의 성분 측정값을 제안한 방법으로 비교 평가한 결과를 ZEUS 2000 지리정보시스템에 저장, 표현할 수 있게 하고 ZEUS/SQLX, ZEUS/COM 그리고 Visual Basic 6.0 프로그래밍 언어를 이용하여 검색, 연구 분석 할 수 있는 사용자 인터페이스를 구현하였다. 연구의 결과 지하수 관정과 다른 지리-객체들의 공간관계성을 확인하였고 지리정보시스템을 이용한 효과적인 안정성 평가지수를 개발하였다. 더욱 많은 지역의 사례에 대한 비교 평가로 제안한 평가 모델을 검증하는 것을 향후 연구과제로 남긴다.

• 한국지반신소재학회논문집
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• 제9권4호
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• pp.57-66
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• 2010

본 연구에서는 현장사례를 이용하여 석산개발이 주변 지역에 위치하는 토양 및 하천의 중금속오염에 미치는 영향을 분석하였으며, 분석결과를 비탕으로 중금속오염에 대한 대책방안을 제시하고자 하였다. 석산개발 부지 인근의 하천 및 토양의 중금속오염 조사결과, 석산개발로 인하여 발생된 미세석분 및 침출수가 삼막천으로 유입되면서 오염을 초래한 것으로 분석되었다. 또한 석산개발 주변지역의 중금속 오염도에 대해, 오염지수를 이용하여 평가한 결과, 오염된 지하수가 삼막천 오염의 주원인인 것으로 분석되었으며, 토양의 중금속오염은 오염된 지하수가 삼막천에 유입되어 중금속이 삼막천 하상에 퇴적된 것으로 확인되었다. 따라서 삼막천 오염의 주원인인 지하수에 대한 중금속 제어는 환경친화적인 반응물질이 적용된 투수성 반응벽체 (PRE, Permeable Reaction Barrier) 시스템을 통하여 수행하는 것이 바람직 할 것으로 판단된다.