• 한국지하수토양환경학회지:지하수토양환경
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• 제19권2호
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• pp.16-24
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• 2014

To test the potential effects of extracellular electron shuttles (EES) on the rate and extent of heavy metal release from contaminated soils during microbial iron reduction, we created anaerobic batch systems with anthraquinone-2,6-disulfonate (AQDS) as a surrogate of EES, and with contaminated soils as mixed iron (hydr)oxides and microbial sources. Two types of soils were tested: Zn-contaminated soil A and As/Pb-contaminated soil B. In soil A, the rate of iron reduction was fastest in the presence of AQDS and > 3500 mg/L of total Fe(II) was produced within 2 d. This suggests that indigenous microorganisms can utilize AQDS as EES to stimulate iron reduction. In the incubations with soil B, the rate and extent of iron reduction did not increase in the presence of AQDS likely because of the low pH (< 5.5). In addition, less than 2000 mg/L of total Fe(II) was produced in soil B within 52 d suggesting that iron reduction by subsurface microorganisms in soil B was not as effective as that in soil A. Relatively high amount of As (~500 mg/L) was released to the aqueous phase during microbial iron reduction in soil B. The release of As might be due to the reduction of As-associated iron (hydr)oxides and/or direct enzymatic reduction of As(V) to As(III) by As-reducing microorganisms. However, given that Pb in liquid phase was < 0.3 mg/L for the entire experiment, the microbial reduction As(V) to As(III) by As-reducing microorganisms has most likely occurred in this system. This study suggests that heavy metal release from contaminated soils can be strongly controlled by subsurface microorganisms, soil pH, presence of EES, and/or nature of heavy metals.

• 한국안전학회지
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• 제32권5호
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• pp.20-24
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• 2017

In this study, we have performed the Cone Calorimeter test in accordance with ISO 5660-1 to check the combustion characteristics of building flooring materials. The fire risk of these materials were evaluated by construction code, KFI criteria and standards of flame retardant performance. When samples exposed to external heat flux, all samples consumed a lot of Oxygen for a long time. So heat release from sample burning continued so long. And also all samples produced so much smoke. Even though a few samples were satisfied with only peak heat release rate criteria, all 8 samples were not satisfied with criteria of peak heat release rate and total heat released together. The results of 5 min total heat released were $15.9MJ/m^2{\sim}5.9MJ/m^2$. It menas the results are more than 2~6 times higher than the criteria. The results of 10 min total heat released were $30.1MJ/m^2{\sim}100.8MJ/m^2$. It means the results are more than 3~12 times higher than the criteria. 6 of 8 samples were not satisfied with Dm.corr.(corrected maximum smoke density) criteria. The building flooring materials which we used for this test ignited very fast and the burning continued so long. It means these samples are susceptible to fire.

• 한국안전학회지
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• 제29권3호
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• pp.114-120
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• 2014

The purpose of this study is to conduct the study of the combustion and thermal characteristics through transportation oil for the analysis of fire hazard. Transportation oil breaks down into fuels such as diesel for civilian demands, gasoline, DF1(diesel for military), high sulfur diesel(for marine), kerosene and JP1(for aviation), and lubricants like brake fluid, power steering oil, engine oil, and automatic and manual transmission oil. The experiments of flash point, ignition point, flame duration time, heat release rate were carried out using TAG closed cup flash point tester(AFP761), Cleveland open cup auto flash point analyzer(AFP762), KRS-RG-9000 and Dual cone calorimeter. As a result, the fuel's ignition points were lower than lubricants, especially that of gasoline was not conducted as it has below zero one. Gasoline has the highest ignition point of about $600^{\circ}C$, while the other fuels showed $400{\sim}465^{\circ}C$. For flame duration time, lubricants had over 300 seconds, but fuels had less than 300 seconds except high sulfur diesel(350 seconds). Total heat release rate ranged $287{\sim}462kW/m^2$ for lubricants and gasoline showed the highest total heat release rate, $652kW/m^2$.

• 한국농공학회논문집
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• 제58권2호
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• pp.1-9
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• 2016

This study aims to assess the effectiveness of activated carbon (AC) and crushed concrete (CC) as capping material to block the release of nitrogen, phosphorus, and organic substance from reservoir sediments. The efficiency of AC and CC as capping material was evaluated in a reactor in which a 1 or 3 cm thick layer of capping materials was placed on the sediments collected from Mansu reservoir in Anseong-city. Dissolved oxygen (DO) concentration, total nitrogen (T-N), total phosphorus (T-P), and chemical oxygen demand (COD) concentration in reservoir water above the uncapped sediments and capping material were monitored for 45 days. The release rate of T-N was in the following increasing order: AC 3 cm ($1.18mg/m^2{\cdot}d$) < CC 1 cm ($2.66mg/m^2{\cdot}d$) < AC 1 cm ($2.94mg/m^2{\cdot}d$) < CC 3 cm ($3.42mg/m^2{\cdot}d$) < uncapped ($4.59mg/m^2{\cdot}d$). The release rate of T-P was in the following increasing order: AC 3 cm ($0mg/m^2{\cdot}d$) $${\approx_-}$$ CC 3 cm ($0mg/m^2{\cdot}d$) < CC 1 cm ($0.03mg/m^2{\cdot}d$) < AC 1 cm capped ($0.07mg/m^2{\cdot}d$) < uncapped ($0.24mg/m^2{\cdot}d$). The release of nitrogen and phosphorus were effectively blocked by AC capping of 3 cm thickness, and CC capping of 3 cm thickness effectively controlled the release of phosphorus. The order of increasing COD release rate was as follows: AC 3 cm ($0mg/m^2{\cdot}d$) $${\approx_-}$$ CC 3 cm ($0mg/m^2{\cdot}d$) < CC 1 cm ($5.03mg/m^2{\cdot}d$) < AC 1 cm ($7.28mg/m^2{\cdot}d$) < uncapped ($10.05mg/m^2{\cdot}d$), indicating that AC and CC capping effectively interrupted the release of organic contaminants from the sediments. It was concluded that AC and CC could effectively block the release of T-N, T-P and COD release from contaminated reservoir sediments.

• 원예과학기술지
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• 제19권4호
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• pp.476-482
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• 2001

서남부지역 양파 재배 시 완효성 비료 시용에 따른 품질향상 효과를 구명하고자 실시된 결과를 요약하면 다음과 같다. 시험 후 토양의 화학성은 속효성 비료보다 완효성 비료 시비구가 약간 높게 나타났고 생육은 조생, 만생종 모두 속효성 비료에 비하여 완효성 비료 시비구가 약간 떨어지는 경향을 보였다. 그러나 노균병 이병률은 완효성 비료 시비구에서 1-7% 더 낮았으며 엽록소와 전질소함량은 관행 시비구가 완효성 비료 시비구보다 높은 경향을 나타냈다. 상품수량은 조생종인 소닉의 경우 관행 시비구 4,365kg/10a에 비하여 완효성 비료 시비구가 15% 증수되었으나 만생종인 창녕대고에서는 UF를 제외하고는 2-11% 감수되었다. 완효성 비료 시비구에서 수확된 양파의 경도, 당도, 인엽수, 인엽두께 등 저장형질은 관행 시비구보다 양호하게 나타났으며 다른 성분들은 유의성이 없었다. 완효성 비료 시비구에서 수확된 양파구의 부패율 및 맹아율은 조생, 만생종 모두 관행 시비구에 비하여 현저히 낮았다.

• 환경영향평가
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• 제7권2호
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• pp.5-14
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• 1998

This study was performed to estimate interrelation between characteristics of sediment and nutrient releare from sediment in Dae-cheong lake. For the investigations, sediments were sampled in June and October 1997 at fish farms, embayment, and the main stream of Dae-cheong lake. Items for investigation are as follows; water content, weight loss on ignition(IG), porosity of sediment, Total Kjeldahl Nitrogen(TKN), content of element(H, N, C), nutrient release rate. Water content and porosity were measured to conjecture the physical trait and grain size. And weight loss on ignition was measured to determine the contents of organic substance. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentration of interstitial water and overlying water were measured. Release rate of nutrients which has direct influenced upon the water quality were 0.05-8.63mg-$P/m^2{\cdot}day$ and 4.99-36.56mg-$N/m^2{\cdot}day$. And it was found that release rate was measured higher in the 1st sampling than in the 2nd sampling. And for determination of the humus level of sediment, carbon and nitrogen content were measured by using elemental analyzer. Generally, C/N ratio is used to determine humus level of lake sediment. As a result of elemental analysis, C/N ratio was determined in the range of 7.64~11.55, so humus level of Dae-cheong lake sediment was estimated from mesohumic state to oligohumic state.

• 한국해양공학회지
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• 제7권1호
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• pp.25-32
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• 1993

In composite materials, the fracture perpendicular to the fiber direction usually shows a non-linear behavior accompannying blunting and plastic deformation around the crack tip. In this study, the fracture thoughness in random short fiber SMC composite material and Carbon/Epoxy composite material is estimated by the A.M.(Area Method) and the G.L.M.(Generalized Locus Method) which can determine a stable total energy release rate(G$_T$) not only in highly elghly elastic material but also in highly non-linear materials.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2013년도 추계학술대회 초록집
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• pp.178-179
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• 2013

본 연구에서는 현재 사용되고 있는 건축물 내의 화장실 칸막이 재료를 대상으로 ISO 5660-1 콘칼로리미터(Cone calorimeter) 실험을 실시하여 대상 실험 재료들의 연소 특성을 비교 평가 하였다. 모두 5종류의 실험체를 사용하였으며, 화재 발생시 연소 중요 평가항목인 착화시간(Time to ignition), 총 방출열량(Total heat release), 최고 열방출율(Peak heat release rate), 평균 열방출율(Mean heat release rate)을 중점적으로 평가하였다. 실험결과, 착화시간은 일반 합판패널에서 빠르게 일어났으며, 총 방출열량, 최고 열방출율, 평균 열방출율은 고밀도 압축패널에서 높게 나타난 것으로 분석되었다.

• 한국화재소방학회논문지
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• 제25권5호
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• pp.62-68
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• 2011

본 연구는 고체가연물의 초기 점화 및 화재성장과정에서의 발열량을 정량적으로 측정하고 가연물에 따른 화재성장특성 파악하고자 한다. 실험에 적용된 고체가연물은 단일/이중 목재크립, 단일/이중 쿠션, 카페트/목재크립이며 화재발달 단계에서 화재성장특성을 시간 제곱 화재성장 시나리오와 비교분석하고 고체가 연물의 화재성장 계수를 정량화 하였다. 고체가연물의 연소과정에서 소모되는 연료의 질량과 방출되는 총열에너지 개념을 이용하여 가연물의 평균 유효연소율을 평가하였으며 환기 및 화재조건의 영향을 분석하여 화재해석시 화재시나리오를 설정하는데 있어서 실질적인 정보를 제공하고자 한다.

• 한국화재소방학회논문지
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• 제24권5호
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• pp.115-121
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• 2010

이 연구에서는 암모늄염을 처리한 리기다 소나무의 연소성을 시험하였다. 실온에서 3종류의 암모늄염 즉, 황산암모늄, 제1인산암모늄, 그리고 제2인산암모늄의 20wt% 수용액에 각각 리기다 소나무를 함침시켜 건조시킨 후 콘칼로리미터(ISO 5660-1)를 이용하여 그의 연소성을 시험하였다. 암모늄염으로 처리한 시험편은 처리하지 않은 시험편에 비하여 그의 연소성을 감소 시켰다. 이것은 연소 억제성이 순수 리기다 소나무 시험편에 처리한 암모늄염 때문에 향상된 것으로 생각된다. 또한 암모늄염으로 처리한 시험편은 처리하지 않은 시험편에 비해 낮은 최대열방출률과 낮은 총방출열량을 나타내었다.