• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.565-569
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• 1999

In these days, the silicone insulators have been increasingly studied and applied for outdoor insulators because it has superior characteristics than porcelain and glass insulators, which have been used for outdoor insulators. First of all, The excellent performance of the silicone rubber in polluted and wet conditions is attributed to the ability of the material to maintain the hydrophobicity of the surface in the presence of severe contamination and wet conditions. This is because of the presence of low molecular weight mobile fluid in the silicone rubber which diffuses to the surface and to above the contamination layer. But, the leakage current and some surface discharge occurs on surface of the composite polymeric insulation materials when the insulator is used for a long time with severe contaminative condition and it can lead the contamination flashover. So the leakage current and the discharge current are important to estimate the condition of the silicone rubber surface. In this paper, the average leakage current, the relation of surface discharge current and phase angle were study to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• Environmental Analysis Health and Toxicology
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• 제14권4호
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• pp.175-187
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• 1999

To investigate the risk perception of environmental issues, two consequtive surveys were conducted to environmental professionals using a standardized questionnaire from September to October in 1999. The number of subjects were 72 for the first survey and 68 for the second one. The questionnaire was consisted of items such as the degree of environmental pollution in Korea, risk perception of some issues on human health and ecosystem, and seriousness of the problems in the real situation in Korea. For the degree of environmental pollution in Korea, the average risk rating in the second test (7.4 point) was significantly higher than that in the first test (7.2 point). The risk perception on the general human health and ecosystem, and the seriousness in Korea situation were analyzed in the order of ′air pollution′, ′water pollution′,′soil contamination′,′waste′,′toxic chemical pollutants′,′food contamination′,′ocean contamination′, ′odor pollution′, and ′noise pollution′. Also ′toxic chemical pollutants′ problem was perceived to be the highest risk on general human health or ecosystem, and on present situation in Korea. ′Automotive vehicle exhaust′ problem was perceived to be the most severe environmental problems among specific 30 items. ′Industrial source air pollution′,′toxic air pollutants′, and ′domestic and industrial source pollutants to surface water′ were relatively severe environmental problems comparing to other problems. The pollution issues were classified into four categories by two aspects of perception; risk in general setting and seriousness in Korea situation. If the issues were highly serious in Korea and low risk perception in general setting then it is named "the Korea-specific group". Those that were all high score in two aspects, named "the Common group". Those that were all low in two aspects, named "the Nonsignificant group". And the issues were high risk perception in general setting and low seriousness in Korean situation, named "the Latent group".

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.187-190
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• 2001

This study is concerned with the hydrodispersive characteristics of granite in Changwon area. A single-well injection/recovery tracer test was conducted to determine longitudinal dispersivity of the granite, using sodium chloride tracer The dispersivity values obtained from the injection phase are 0.48 m (for between PW-1 and OW-3) and 0.72 m (for between PW-1 and OW-4). That obtained from the recovery phase is 0.68 m. The result of the tracer test indicates that the anisotropy and heterogeneity of the granite and the direction of flow.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.169-172
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• 1995

Establishment of a diagnosing technology for the deterioration of reinforced concrete structures due to salt contamination is urgent, but few analytical methods based on measured data obtained from concrete structures have been presented so far. Chloride penetration into concrete from sea water is generally understood and analysed as diffusion of chloride ion. This paper presents a new method of predicting chloride penetration into concrete based on diffusion theory. Also, it determines the duralility of Marine structure in service with the prediction of remaiing lifetime by the carvonation test.

• 미생물학회지
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• 제25권1호
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• pp.73-79
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• 1987

A restriction endonuclease, Kpn I has been isolated from Klebsiella pneumonia. Cells were broken by sonication. After ultracentrifugation the supernatant containing Kpn I activity was further purified by Sepharose-6B gel filtration, DEAD-Cellulose, Heparin-Agarose, and Aminohexyl-Agarose column chromatography. Final enzyme preparation was essentially free of contamination exonuclease and phosphatase, as judged by ligation-recut test. Total activity of the enzyme recovered from 10 grams of cells was $4.7\times 10^5$ units.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.219-226
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• 2002

Filtration performance of an automotive fuel filter was evaluated based on the theory of Beta ratio. This study also introduced the fuel components' contamination performance test stand incorporating the multi-pass filtration test circuit. The theoretical basis of multi-pass test and test procedure were described in detail. The specification of commercial fuel filter currently available was just the maximum pressure drop across the filter assembly and the holding capacity of contaminants. However, test results revealed that the fuel filter tested could not maintain consistent Beta ratio, that is filtration efficiency, although it had the holding capacity close to the specification. Hence the Beta ratio should be specified in service life. The results also showed that filtration system model should be refined including desorption ratio to estimate the variable Beta ratio in the test.

• Journal of the Korean Wood Science and Technology
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• 제43권4호
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• pp.504-510
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• 2015

본 연구는 국내에서 사용되는 ACQ 방부처리목재로부터 토양으로 용탈된 구리에 의해 발생되는 토양오염 정도를 평가하기 위하여 수행되었다. 야외시험장에서 3년 동안 노출된 방부처리목재 주변의 토양을 분석하여 구리의 용탈량 및 용탈된 구리의 이동범위를 산정하였으며, 전남 및 경남에서 ACQ 방부처리목재가 사용된 데크 주변의 토양을 분석하여 구리에 의한 토양오염 정도를 평가하였다. 야외노출시험은 방부처리목재의 횡단면에서 용탈되는 구리의 양이 목재의 측면에서 용탈되는 구리의 양보다 1.5배 이상 높다는 것과 토양 내에서의 구리의 이동이 매우 제한적인 것을 보여주었다. 근린공원에 설치된 데크 기둥 주변의 토양 분석은 방부처리목재로부터 10 cm 이내의 토양 내 구리 함유량이 대부분 2지역 토양오염우려기준인 500 mg/kg을 초과하지 않았다는 것을 보여주었다. 야외노출시험의 경우 깊이 10 cm 이내의 토양에서 구리의 분포범위가 사용 중인 데크 기둥 주변의 토양에서보다 훨씬 넓은 것으로 나타났는데 이는 야외노출시험에 사용된 방부처리목재의 약제보유량이 데크 기둥의 경우보다 두 배 이상 높은 것에서 기인한다고 판단된다.

• 대한소아치과학회지
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• 제34권1호
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• pp.73-80
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• 2007

소아 환자의 인접면 우식을 치료할 때 컴포머는 불소를 방출하는 재료로 유용하게 사용될 수 있다. 하지만 구강내 환경은 항상 습윤한 상태로 타액은 컴포머와 치질 사이의 접착을 방해할 수 있다. 수복시에 타액이 게재하게 되면 미세누출이 발생할 가능성이 높아지게 되며 그로 인해서 수복의 실패가 일어날 수 있다. 이에 본 연구에서는 컴포머를 수복할 시에 타액의 영향과 수복 방법에 따른 미세누출 정도를 평가하기 위해서 시행하였다. 컴포머로서 Dyract $AP^{(R)}$(Dentsply, Germany)를 사용하였으며 Dentin bonding agent로는 Prime and $Bond^{(R)}$ NT (Dentsply, Germany)를 사용하였고, 광중합을 위해서 Elipar Trilight (3M ESPE, USA)를 사용하였다. 구강내 환경을 재현하기 위해서 saliva pool을 제작하였다. 소구치 2개를 인접하여 시편을 제작한 후에 2급 와동을 형성하여 수복 환경을 다르게 하여 컴포머를 충전한 후에 500회 thermocycling하였다. 그 후 0.5% methylene blue 용액에 24 시간 동안 담근 후에 실체 현미경을 통해서 교합면과 치은면에서의 미세누출 정도를 측정하였다. Kruskal-Wallis Test와 Mann-Whitney Test를 이용하여 각 군간 유의성을 검정하여 다음과 같은 결과를 얻었다. 1. 교합면에서의 각 군간 통계학적 차이는 없었다(p>0.05). 2. 치은면에서 $Oraseal^{(R)}$을 이용하여 수복한 3군이 타액 오염을 시키지 않은 4군과 통계학적 차이가 없었다(p>0.05). 3. 치은면에서 1군과 2군 사이에는 통계학적 차이가 없었다(p>0.05). 4. 치은면에서 $Oraseal^{(R)}$을 이용하여 수복한 3군이 1, 2군보다 통계학적으로 더 낮은 미세누출 정도를 보였다(p<0.05).

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권3호
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• pp.52-60
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• 2010

The stone-dust is an unavoidable by-product of aggregate production, which is produced about 0.8~1.0 million $m^3$ annually. The stone-dust is currently regarded as a hazard material on environment because it is classified as an industrial waste in the Waste Management Law of Korea. At present, the stone-dust is considered as a environmentally hazardous material, and is classified as an industrial waste according to the Waste Management Law of Korea. In this study, we assessed the heavy-metal contamination of the stone-dust on surrounding environments by various leaching tests. Leaching experiments (such as Korea Standard Leaching Procedure (KSLP), Soil Environment Preservation Act of Korea (SEPAK), Toxicity Characteristic Leaching Procedure (TCLP), and Synthetic Precipitation Leaching Procedure (SPLP)) show that very low heavy metals (As, Cd, Cu, Pb, Zn, Hg) and CN are leached out, or much less than each regulatory thresholds. The resuts of the leaching test with time in acidic solution (initial pH 5 and 3) indicate that pH-buffering minerals are present in the stone-dust. These results suggest that the stone-dust can not potentially affect adverse impact on surrounding environments such as surface water, groundwater and soil etc..

• 한국식품위생안전성학회지
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• 제15권3호
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• pp.204-208
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• 2000

1996년 3월부터 1998년 10월간에 경남지방의 시판 냉장 및 냉동우육 350건,돈육 338건 및 계육 350건으로부터 최확수법(MPN)을 이용하여 식중독균의 오염수준을 조사하였다. Staphylococcus aureus의 경우 10∼10,000 CFU/8으로 비교적 높은 오염수준은 나타내었고, Salmonella 및 Listeria monocytogenes는 0,9 MPN/g 이하였으며, Campylobacter jejunilcoli는 7.0 MPN/g (cm2)이하였다. 분리된 4종류의 병원세균에 대하여 냉장우육의 14.3%,돈육의 25.3% 및 계육의 55.0%가 1종류에, 그리고 우육 2.7%,돈육 5.6% 및 계육의 14.7%가 2종류에, 돈육의 2.4%가 3종류의 병원세균에 교차오염 되어있었다. 일반적으로 병원세균은 냉장계육에서 보다 냉동 포장계육에서 더 높은 분리 빈도를 나타내었다.