• Journal of the Korean Wood Science and Technology
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• 제47권6호
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• pp.667-673
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• 2019

The performance of a wooden deck made of refractory materials that have difficulties in achieving target penetrations as stipulated in the specification and quality standards for treated wood in Korea, was assessed via a case study in this research. A wooden deck built in Jinju in 2009 was selected for this study because of its fabrication method using pressure and treated refractory materials. The penetration and retention analysis did not satisfy the domestic standard for treated wood. Inspection of the deck in 2019 revealed that the deck had been attacked by decay fungi. Cap rails showed much deeper and wider checking on their surface compared with the top and base rails, resulting in a severe fungal attack. The decking boards exhibited severe fungal decay primarily in the end parts. However, the rails and balusters without checks and posts were virtually free of fungal attack irrespective of the preservative penetration measures. Copper content in the soil 5 cm away from the deck was less than 150 mg/kg, implying that copper movement in the soil was very limited. These results suggest that the inhibition of surface propagation and the protection of end surfaces are essential factors in increasing the longevity of treated wooden decks; further, the results also showed that the deck was within an acceptable range from the point of copper contamination.

• 대한소아치과학회지
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• 제43권1호
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• pp.36-43
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• 2016

이 연구의 목적은 혈액오염 시 Biodentine$^{(R)}$, Theracal$^{(R)}$, mineral trioxide aggregate(MTA)의 압출강도를 측정하고 표면형태를 관찰하는 것이었다. Biodentine$^{(R)}$, Theracal$^{(R)}$, MTA 각각의 재료를 2개의 그룹으로 나누었다. 대조군은 phosphate buffered saline 용액 조건에서, 실험군은 fetal bovine serum 조건에서 4일간 $37^{\circ}C$에서 보관하였다. 이후 압출강도를 측정하고 주사전자현미경을 이용하여 표면형태를 분석하였다. Biodentine$^{(R)}$과 Theracal$^{(R)}$은 모든 조건에서 MTA보다 유의하게 더 높은 압출강도를 보였고 혈액오염 시 모든 재료의 압출강도는 유의하게 감소하였다. 표면형태 관찰결과 혈액오염 후 모든 재료의 표면형태가 변화하였다. 혈액오염 조건에서 Biodentine$^{(R)}$과 Theracal$^{(R)}$은 MTA와 비교하여 더 높은 압출강도를 보였으므로 혈액오염 조건에 사용하기에 더 적절할 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.259-259
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• 2009

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, they are not suited to outdoor insulator by reason of being not good hydrophobic. RTV has a good property of hydrophobic and ATH has characteristic obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained nano size ATH coat on surface of engineering plastics. In this paper, it compares resistance tracking of the engineering plastic coated RTV with that of non-coated engineering plastic and ATH filled composites performed much better than non-filled composites.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.29-29
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• 2010

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, it isn't suited to outdoor insulator because it is not hydrophobic. RTV(Room temperature vulcanizing) has a good property of hydrophobic and micro-filler. nano-filler have characteristics of obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained with micro, nano-filler coating on surface of engineering plastics. In this paper, it compares tracking resistance, leakage current of the engineering plastic coated RTV with that of non-coated engineering plastic. And filled-composites performed much better than non-filled composites.

• 공업화학
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• 제31권5호
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• pp.481-486
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• 2020

삼척항 내 표층 퇴적물에 대한 지화학적 특성을 파악하기 위하여 입도, 유기물 및 중금속 분포 특성을 조사하였다. 삼척항 퇴적물은 sand, silt, clay가 혼재된 특성을 보였으며, 내항에는 세립질이 우세하였고, 외항에는 조립질이 우세한 것으로 나타났다. 표층 퇴적물의 유기물(COD, TOC, IL) 오염정도는 내항이 외항보다 더 심한 것으로 나타났으며, 총질소 및 총인 농도도 내항이 더 높은 것으로 나타나고 있다. 또한 중금속 농도도 외항보다 내항에서 더 높았다(As 제외). 내항 표층 퇴적물의 높은 유기물 농도 및 C/N비로 보아 육상 유래 유기물의 오염 기여가 큰 것으로 판단된다. 표층 퇴적물의 입도, 이화학적 성분, 중금속 간의 상관성 분석에서 silt-clay는 중금속과 높은 상관성을 보였고, 유기물 지표와 중금속간의 상관성도 대체적으로 높게 나타났다. 중금속 연속추출결과에 따르면 Ni, Zn, Cu, Pb, Cd 및 As는 이온교환, 탄산염, 산화물 형태를 합한 평균 존재비가 각각 14.8, 49.8, 39.1, 32.2, 51.8 및 26.6%이었다.

• 한국환경과학회지
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• 제6권6호
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• pp.679-688
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• 1997

In order to analyze the water quality variation of surface water around the Sudokwon landfill site, seasonal variations of water temperature, pH, DO. HOD, COD, SS, NH3-N, NO2-N, and NO3-N were examined at 10 sites from January to December, 1996. It was found that the estimates of COD, DO. SS, and $NH_3-N$ were Increased compared with the results of environmental Impact assessment carried out In 1988. Higher estimates of COD, DO, and SS were due to Industrial and agricultural wastewater, and the Increase of NH3-N at Jangdo reservoir strate was due to the leachate from the landfill. In particular, the estimate of 55 was found to be increased by the soil wash from the landfill during the heavy rainy days.

• 구강회복응용과학지
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• 제35권1호
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• pp.27-36
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• 2019

목적: 치과 치료에 사용되는 일부 비위험 기구들에 대한 치과의사의 감염 관리 인지도와 감염 관리 실태를 조사하고자 하였다. 연구 재료 및 방법: 대전광역시, 충청남도, 충청북도 및 전라북도 지역의 40개 치과 병, 의원을 연구 대상으로 하였다. 감염 관리에 대한 치과의사의 인지도와 실천정도에 관해서 설문 조사를 시행하였고, 연구 대상인 치과의사가 치과 치료에 사용하는 인상용 건, 광중합기, 3-way syringe, 색조 견본, 치실통의 표면 오염도를 아데노신 3인산 측정기를 이용하여 측정하였고, 감염 관리에 대한 인식도와 실태 간의 상관관계를 분석하였다. 결과: 감염 관리에 관한 인지도와 시행 빈도는 3-way syringe에서 가장 높았다. 모든 기구에서 소독액을 사용한 표면 소독이 가장 많이 시행되었다. 표면 오염도는 3-way syringe, 색조 견본이 인상용 건, 광중합기, 치실통보다 낮게 나타났다. 결론: 치과 치료에 사용되는 비위험 기구들 중에서 3-way syringe는 사용자의 감염 관리 인지도와 표면 오염도 간에 유의한 상관관계가 있으며, 감염 관리의 인지도가 높을수록 표면 오염도가 낮은 것으로 나타났다.

• 핵의학기술
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• 제14권2호
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• pp.128-132
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• 2010

핵의학과 종합조작실은 방사선 관리구역으로 이곳에서 발생된 방사성오염물질은 방사성폐기물로 간주하여 일반쓰레기와 별도로 관리를 해야 한다. 본 실험은 우리가 미처 인식하지 못해 일반쓰레기로 처분되었던 방사성오염물질의 오염도를 측정하고 원인을 분석하여 보다 적극적인 방사성폐기물 관리 운영의 필요성을 제시하고자 함이다. 측정대상은 방사성의약품을 표지하기 위해 사용된 생리식염수와 $^{99}Mo$/$^{99m}Tc$ generator(국산 및 외산)에서 발생한 generator cap, saline needle cap, $^{99m}Tc$-needle cap, saline vial로 하였고, gamma survey meter를 이용하여 평균값과 표준 편차(mean${\pm}$SD)로 나타냈다. 측정대상물질의 오염유무를 알기 위해 방사선 관리구역에서 반출될 수 있는 물질의 표면오염도인 최대허용표면오염도의 1/10(43.2 cpm)을 기준값으로 정하였다. 각각의 표면오염도를 측정한 결과 방사성의약품 표지를 위해 사용된 생리식염수에서는 $14,429{\pm}26,378$ cpm으로 최대 허용표면오염도의 1/10을 초과하였다. 그리고 측정된 generator중 외산에서는 generator cap: $17{\pm}28$ cpm, saline needle cap: $35{\pm}66$ cpm, $^{99m}Tc$-needle cap: $9{\pm}21$ cpm, saline vial: $13{\pm}28$ cpm으로 최대허용표면오염도의 1/10를 초과하지 않았지만 국산에서는 generator cap: $22,852{\pm}52,545$ cpm, saline needle cap: $87,367{\pm}109,711$ cpm, $^{99m}Tc$-needle cap: $9,008{\pm}10,459$ cpm, saline vial: $186,416{\pm}158,196$ cpm으로 최대 허용표면오염도의 1/10를 초과하였다. 외산 generator에서 발생한 측정대상물질은 일반폐기물로 처분하고 국산 generator와 방사성의약품을 표지하기 위해 사용된 생리식염수는 반드시 방사성폐기물로 간주하여 처분해야 한다. 따라서 일반쓰레기 뿐만 아니라 종합조작실에서 반출되는 모든 물질에 대한 자체적인 방사선측정, 기록 및 비치와 방사성폐기물에 대한 지속적인 교육을 통해 방사성 폐기물이 일반쓰레기로 처분되어 나가는 것을 예방 할 수 있을 것이다.

• 한국습지학회지
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• 제9권1호
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• pp.79-89
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• 2007

This paper provides a comprehensive overview of the present status of several environmental problems caused by emerging toxic substances such as persistent organic pollutants (POPs), endocrine disrupting chemicals (EDCs), and arsenic in various environmental media in Vietnam. Monitoring data reported during the 1990s demonstrated elevated contamination of DDTs in most of these compartments in Vietnam. Studies in frame of the Asia-Pacific Mussel Watch Program revealed that fish, mussels and resident birds from Vietnam contained higher concentrations of DDTs as compared to other countries in region, suggesting the role of Vietnamese environment as a significant emission source of DDT in the Southeast Asian region. The estimated dietary intakes of PCBs and DDTs for Vietnamese were relatively high among Asian developing countries, suggesting potential risk for humans posed by thesechemicals. Widespread contamination of some endocrine active compounds such as alkylphenols and phthalates was observed at various sites along the coasts of northern and middle Vietnam. The presence of significant source of bisphenol-A along Red River estuary was revealed with the concentrations comparable to those reported for developed nations. A case study on seasonal variation of alkylphenols and phthalates in surface water of river delta and estuary of north and middle Vietnam indicated the differences in distribution of these compounds between dry and rainy seasons. Higher concentrations of alkylphenols and phthalates were found in dry season in estuary; while the contrasting pattern was observed in the river delta, showing elevated residues in rainy season. This result suggests the different behavior of alkylphenols and phthalates in river delta and coastal environment. From ecotoxicological perspectives, concentrations of bis-phenol A and di(2-ethylhexyl)phthalates [DEHP] in surface water from some locations in Vietnam exceeded the guideline values for Ecotoxicological Effects and the Environmental Risk Limit, respectively, suggesting potential for toxic implications on aquatic wildlife. Widespread and elevated arsenic contamination was discovered inour recent surveys in groundwater in a large area of suburban areas of Hanoi city, the capital of Vietnam. The most recent investigation in 4 villages showed about more than 50 % of groundwater samples contained As concentrations exceeding 50 g/L (the WHO and Vietnamese standard). In particular, in Son Dong villages, 58 % of samples analyzed contained As concentrations higher than 200 g/L. Good correlations were found in As concentrations in water and hair and urine of peoples in corresponding families, suggesting the chronic exposure to As by people living in As-contaminated ground water areas. In Son Dong village, As levels in hair (mean: 1.7 mg/kg dry wt) and urine (g/g creatinine) exceeding the reference values recommended by WHO, suggesting potential for human risk posed by long term accumulation of As in human body. Future studies should be focused on the time trends of POPs and EDCs in biota in Vietnam in order to predict future trend of contamination and to reveal new clues for understanding possible toxic impacts on aquatic organisms. The issues of arsenic contamination in groundwater and their chronic toxic implications on human health should be systematically investigated in the future.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.734-739
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• 2000

Vortices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface is totally different from the clean free surface case.