• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.9-18
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• 2017

Arsenic (As) has been considered as the most toxic one among various hazardous materials and As contamination can be caused naturally and anthropogenically. Major forms of arsenic in groundwater are arsenite [(As(III)] and/or arsenate [(As(V)], depending on redox condition: arsenite and arsenate are predominant in reduced and oxidized environments, respectively. Because arsenite is much more toxic and mobile than arsenate, there have been a number of studies on the reduction of its toxicity through oxidation of As(III) to As(V). This study was initiated to develop photocatalytic oxidation process for treatment of groundwater contaminated with arsenite. The performance of two types of light sources (UV lamp and UV LED) was compared and the feasibility of goethite as a photocatalyst was evaluated. The highest removal efficiency of the process was achieved at a goethite dose of 0.05 g/L. Based on the comparison of oxidation efficiencies of arsenite between two light sources, the apparent performance of UV LED was inferior to that of UV lamp. However, when the results were appraised on the basis of their emitting UV irradiation, the higher performance was achieved by UV LED than by UV lamp. This study demonstrates that environmentally friendly process of goethite-catalytic photo-oxidation without any addition of foreign catalyst is feasible for the reduction of arsenite in groundwater containing naturally-occurring goethite. In addition, this study confirms that UV LED can be used in the photo-oxidation of arsenite as an alternative light source of UV lamp to remedy the drawbacks of UV lamp, such as long stabilization time, high electrical power consumption, short lifespan, and high heat output requiring large cooling facilities.

• Korean Journal of Environment and Ecology
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• v.21 no.5
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• pp.400-414
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• 2007

This study has analyzed the vegetation structure to suggest a vegetation ecological restoration model by using the case of the afforestation for erosion control area with Pinus koreaiensis and Betula platyphylla, etc., on the hills of the Young-in mountains after its great fire in 2000. Of the area having a dimension of $1,152,404.3m^2$ selected as a survey site for the existing vegetation, the forest fire area accounted for 69.2% among which, brushwoods accounted the most for 24.67%. As a result of analysis of the 27 surveyed unit plots[unit dimension: $100m^2$] set up in consideration of the existing vegetation pattern and damaged state from the forest fire, the surveyed area was classified into 10 communities. Shrub layer's vegetation was found to be dominant in forest fire areas and the surveyed sites were classified into 5 plant communities, i.e. P. koraiensis community, Quercus variabilis community, P. thunbergii community, Q. serrata community, B. platyphylla community in forest fire areas, while non-forest fire areas were classified into 5 plant communities, such as P. densiflora community, Q. acutissima community, Q. serrata community, Q. mongolica-Q. serrata community, B. platyphylla community. Species diversity of forest fire areas was $0.3679{\sim}0.5907$ and that of non-forest fire areas was $0.5728{\sim}0.8865$. In addition, the number of the species in the forest fire areas was $5{\sim}8$ and that of non-forest areas was $8{\sim}12$; however, the population of forest fire areas$(156{\sim}456)$ was higher than that of non-forest fire areas$(61{\sim}227)$. In the analysis of growth density per layer$[of\;100m^2]$, there appeared $1{\sim}8$ trees of Q. mongolica and $3{\sim}5$ trees of Q. serrata in the upper layer species; $2{\sim}4$ trees of Q. serrata and one tree of Q. mongolica in the canopy layer. As for the characteristics of soil, acidity of forest fire areas was pH 5.45 and that of non-forest fire was pH 5.25. By setting up the middle D.B.H range of Q. mongolica-Q. serrata community as the vegetation restoration model, planting species, planting density and planting models are suggested.

• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.31-40
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• 2014

LNG storage outer tank is a vertically and horizontally prestressed concrete wall structure. Therefore, when the storage tanks become larger, prestressing tendons become longer and eventually the prestressing loss becomes larger. Also, recently, bomb terrors and accidental crashes have occurred frequently on important infrastructures. Therefore, LNG storage tanks are also exposed to these dangerous scenarios, where they need to be evaluated and protected from these threats. Therefore, in this study, the behavior of 270,000 kL LNG storage outer tank impacted by a flying object is evaluated using implicit FEM code, LS-DYNA. In the analysis, the prestress loss due to the increased length of prestressing tendons from enlargement of outer tank is considered. A comparison study between the LNG tanks with and without prestress loss is performed to investigate the impact behavior and the effect of prestressing force change on the safety and serviceability prestressed concrete containment.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.25-31
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• 2018

In this study, the Controlled Low Strength Material (CLSM) was investigated to utilize the bottom ash and fly ash generated in the Circulating Fluidized Bed Combustor (CFBC). It was confirmed that the CFBC fly ash (CFBC-F) and CFBC bottom ash (CFBC-B) had an irregular particle shape through SEM measurement. According to the results of the hazard analysis, it was also confirmed that they were environmentally safe. In the case of mixing with CFBC-F, the unit quantity was increased. Regarding the rate of change of length, shrinkage in the range of -0.05~0.50% occurred in the air dry curing condition and expansion in the range of 0.1~0.6% in the sealed curing condition. Compressive strength was increased in the sealed curing condition compared to the air dry curing condition because there was enough moisture for hydration reaction in the long term. Therefore, the results of this study are likely be used as basic research data of mine filler materials.

• Journal of Environmental Impact Assessment
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• v.9 no.4
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• pp.257-269
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• 2000

This study is to investigate the methodology and applicability on emission control by both MECHANICAL Model and Fugitive Dust Model (FDM) through the comparison of field measurement data and calculated data. Comparing to the method of AP-42 emission fector on the production of flying dust the MECHANICAL Model was proved to be more applicable to the calculation emission rate on the various dust emission conditions on a unpaved road. The seperate calculation on annual mean emission amount and a 24working hours amount was undertaken for the easy management of fugitive dust. Dust concentration predicted by FDM is similar with a measurement value.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.275-278
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• 2006

본 연구는 전정색(panchromatic) 고해상도 위성영상을 이용하여 산화피해림과 비산화림을 대상으로 수종별로 구분하여 조사하였다. 제안된 방법은 회색단계 공발생 행렬(Gray Level Co-occurrence Matrix, GLCM)을 통하여 생성된 질감 영상(textural images)과 웨이블릿 분해 영상(wavelet decomposition images)의 융합을 실시하여 질감 영상에서 추출될 수 있는 정보와 웨이블릿 분해를 통해 얻을 수 있는 정보를 획득하고자 하였다. 그 결과로 동일 수종을 형성하는 임반이나 산화피해 정도가 유사한 산림의 경우 영상의 밝기값의 분포가 일정한 범위 내에서 형성되어 수종 분류 및 산화피해 등급의 구분이 가능했으나, 영상 내 경계효과(edge effect) 현상은 일부 영상에서 나타났다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.432-435
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• 2012

섬유공업에서 텐터기는 가장 필수적인 가공설비이지만, 화재가 가장 많이 발생하는 설비이다. 하지만 현재까지 텐터기의 화재위험성에 대한 인식 및 연구가 부족한 편이다. 이에 본 연구에서는 텐터기 화재의 위험성을 분석하고자 국내 최대 섬유공장 밀집지역인 대구서구지역 비산염색공단의 화재사례를 바탕으로 텐터기의 화재위험성을 분석하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.827-832
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• 1995

한국원자력연구소 실증소각시설의 성능 및 운전성을 입증하기 위하여 방사성동위원소를 포함한 모의폐기물 및 원자력발전소 발생 방사성폐기물에 대한 시험소각을 실시하였다. 비휘발성인 $^{60}$Co 및 $^{54}$Mn의 거동은 비산재의 거동과 거의 유사하였으며 각각의 제염계수는 4.7 x $10^{5}$및 6.2 x $10^{5}$이었다. 반휘발성인 $^{137}$Cs의 경우에는 8$50^{\circ}C$ 및 $700^{\circ}C$의 다른 소각온도에서 각각 2.8 $\times$ $10^4$, 2.6 $\times$ $10^3$으로 소각온도의 의존성을 보여주었다. 원자력발전소에서 운반된 건조 방사성폐기물(DAW)에 대한 시험소각은 성공적으로 수행되었다. 총 베타/감마 방사능에 대한 제염계수가 1.1 $\times$ $10^{5}$이었으며 결과적인 연돌에서의 배출농도는 0.019 Bq/N㎥으로 기체상 배출물에 대한 최대허용농도를 만족시킬 수 있었다.수 있었다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.60-66
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• 2002

본 연구는 진동형 구기자 수확기를 개발함에 있어서 탈과된 열매를 손상없이 집과하여 수확작업의 노동력 및 경제적 비용을 줄이고, 농산물 수확의 기계화를 활성화 시키는데 그 목적을 두었다. 생물학적, 재배학적, 그리고 환경적 요인들을 고려하여 탈과열매의 효과적인 집과를 위한 집과장치를 설계·개발하고, 성능시험을 실시하여 집과장치의 집과효율을 분석 하였으며, 그 결과는 다음과 같다. 1. 수확시작기의 주행시에는 집과안내장치가 구기자 나무 밑부분과 부딪침이 없고, 탈과작업시에는 구기자 나무 밑의 공간까지 집과기능을 갖도록, 4절 링크 시스템을 이용하여 집과 안내장치를 개폐식으로 설계제작하였다. 2. 개폐식으로 제작된 집과장치를 진동형 구기자 수확기 시작기에 장착하여 성능시험을 한 결과, 숙과의 수집율은 88∼96%로 나타났다. 3. 미수집율인 4∼12%는 개폐식 집과장치의 기능저하로 인하여 발생한 것이 아니고, 기계전후 방향의 열매의 튐 현상에 의한 것이었으며, 이 손실은 비산방지막 커튼의 설치로 보완되리라 사료되었다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.227-230
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• 2010

본 논문은 부산 실내사격장 화재와 관련하여 급격한 연소 확대 경로 및 발화원인에 대하여 분석하였다. 연소 확대 경로 분석을 위하여 실내사격장에 광범위하게 사용되는 스펀지형 흡음재의 연소실험을 수행하였다. 흡음재 연소 실험은 일반형과 낭연 처리된 흡음재를 대상으로 실시하였으며, 화약잔사 흡착 시, 연소 특성을 평가하였다. 발화원인에 대한 분석을 위하여 총기 사용 과정에서 발생되는 유탄된 탄환의 비산거리 및 크기를 실측하고, 유탄된 탄환에 대한 운동에너지 계산을 통하여 화약잔사와 충격하는 경우, 충분한 발화 가능성이 있음을 확인하였다.