• 자원환경지질
• /
• 제26권2호
• /
• pp.217-226
• /
• 1993

Stream sediment samples were collected in the vicinity of the Sambo Pb-Zn-barite mine in order to investigate dispersion patterns and pollution levels of heavy metals, and to find out their mode of occurrences. Those samples were analyzed for Cd, Cu, Pb, Zn, Fe, and Mn by using partial extraction and sequential extraction methods. Stream sediments of this studied area has been contaminated severely by Pb, Zn, and Cd. Dispersion patterns of heavy metals in those sediments are different according to their pollution source and sampling distance from the mine. The stream sediment pH is generally neutral in control area, and is slightly acidic in the lower part of tailing dam. The main pollution source of stream sediments was confirmed as tailing and mine drainage. Their pollution level depends mainly on inflowed water and distance from the mine. The tolerance index ranges from -0.9 to 0.7. The mode of occurrances of heavy metals in polluted stream sediment are identified as Fe-Mn oxides, organic bounded and carbonate-bounded compound which show high potential of bioavailablity.

• 대한화학회지
• /
• 제55권6호
• /
• pp.1018-1023
• /
• 2011

Alzinc is a ursine situated in the Ghazaouet town western part of the republic of Algeria. The purpose of this study was to determine the degree of contamination which soil and plants are burdened with some heavy metals: Pb, Zn, Ni, Cu, Cd, Mn, Cr, Fe and As, then the accumulation of heavy metals in the soil and plant adjacent of area the alzinc ursine was detected and the interdependence of pollution among all three regions of the environment determined. This paper analyzes the heavy metal contents within a 2-years period in the soil and plants at the beginning of the vegetation period. The presence of Pb, Zn, Ni, Cu, Cd, Mn, Cr, Fe and As, in the samples were analyzed using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Measurements of heavy metal contents were performed at three locations in soil and vegetative parts of three-plant types (plant alimentary) period during summer. The plant samples from the immediate environment of the dumpsite were highly contaminated with Zn, Cd and Mn. Three plants species: grape, artichoke and pepper, particularly, grape met some of the conditions to be classified as accumulators for Zn, Cu, Cd and Fe, consequently, she revealed a health risk for human and livestock due to the spread of the metal pollution from waste dumpsites to agricultural areas.

• 한국미생물·생명공학회지
• /
• 제29권2호
• /
• pp.122-126
• /
• 2001

공업지역이 밀집한 수도권을 포함하고 있는 경기도의 하천을 대상으로 생화학적 산소요구량이 20ppm 이상으로 오염도가 높은 하천 4개 지역과 2ppm 이하로 비교적 청정한 3개 지역의 토양에서 terephthalic acid를 탄소원으로 생육하는 11개 균주를 분리하였다. 이들 균주들 중, 최적 생장온도와 최대 분해활성을 나타내는 온도가 일치하지 않는 균주도 존재하였지만 대부분은 $30^{\circ}C$에서 최적 생장을 나타냈다. Phthalic acid 이성질체를 탄소원으로한 고체배지에서의 생장과 액체배지에서의 이성질체 분해능력을 비교한 결과, 분리균들은 대체로 한 개 또는 두 개의 phthalic acid 이성질체를 이용하여 생장하는 것으로 나타났고, 오염도가 높은 지역에서 분리된 균들의 phthalic acid 이성질체 분해활성이 오염도가 낮은 지역에서 분리된 균들에 비해 높은 것으로 나타났다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제16권1호
• /
• pp.71-81
• /
• 2011

Cause of contamination in the study area nearby Jang Hang Refinery is dust scattering in refinery stack, and soil washing treatment is one of the proper technologies for soil remediation in this area. Site conditions frequently limit the selection of a treatment process. A treatment technology may be eliminated based on the soil classification or physicochemical characteristics of soil. This study was assessed the soil washing efficiency by conducting of soil characteristic analysis in the vicinity of Jang Hang Refinery Stack within a 2 km radius. Also, it was decided about remedial range with comparative analysis of As in soil by Korean Standard Test Method before/after revision, whereupon As concentration in soil showed a increasing tendency after revision. As a result, the soil washing using the size separation of soil was determined through identifying of As species in the soil. In this site, only particle size distribution and water content of soil can provide the initial means of screening for the potential use of soil washing.

• 한국재료학회지
• /
• 제19권7호
• /
• pp.386-390
• /
• 2009

Niobium(Nb) and Tantalum(Ta) are rarely found apart in nature and never in the free state. The element niobium amounts to 3% of the crustal abundance. On the whole, the niobium capacitor showed somewhat more unstable characteristics than the commercial tantalum capacitors, but is nonetheless considered applicable as a future substitute for tantalum capacitors. In this study, niobium powder was made from potassium heptafluoroniobite($K_2NbF_7$) by using sodium(Na) as a reductant and KCl and KF as diluents based on the hunter sodiothermic reduction method.,In order to obtain a high surface area niobium powder via the sodiothermic reduction method, a certain amount of diluent, such as alkali metal halides selected from NaCl, KCl, KF and NaF, was added in the raw materials to be reduced. However, if a higher surface area of powder is required, more diluents need to be used in the said method in order to produce niobium powder. But when more diluents are used, the niobium powder will be contaminated with more impurities and the yield will also decreased.

• Smart Structures and Systems
• /
• 제23권2호
• /
• pp.195-205
• /
• 2019

An accurate non-model-based method for delamination identification of laminated composite plates is proposed in this work. A weighted mode shape damage index is formulated using squared weighted difference between a measured mode shape of a composite plate with delamination and one from a polynomial that fits the measured mode shape of the composite plate with a proper order. Weighted mode shape damage indices associated with at least two measured mode shapes of the same mode are synthesized to formulate a synthetic mode shape damage index to exclude some false positive identification results due to measurement noise and error. An auxiliary mode shape damage index is proposed to further assist delamination identification, by which some false negative identification results can be excluded and edges of a delamination area can be accurately and completely identified. Both numerical and experimental examples are presented to investigate effectiveness of the proposed method, and it is shown that edges of a delamination area in composite plates can be accurately and completely identified when measured mode shapes are contaminated by measurement noise and error. In the experimental example, identification results of a composite plate with delamination from the proposed method are validated by its C-scan image.

• 한국지반신소재학회논문집
• /
• 제8권3호
• /
• pp.35-44
• /
• 2009

본 연구는 유류나 각종 비수용성오염물질로 오염된 지반에 인공동결공법을 이용한 차수벽을 형성하여 지하수의 이동으로 인한 오염물질의 확산을 방지하기 위한 기초적 실험결과이다. 즉, 인공동결공법을 사용하여 동결차수벽을 형성하는데 있어 각각 포화도가 80%, 90%인 시료를 조성하여 동결모형실험을 수행하였다. 인공동결공법을 이용하여 형성시킨 동결차수벽이 동결시간이 길어짐에 따라 포화도 90%인 시료가 포화도 80%인 시료보다 1시간정도 차수벽이 빨리 형성되었다. 또한, 동결진행시간 12시간 이후의 동결차수벽은 두 시료 모두 가장 얇게 형성된 곳이 50mm의 두께로 형성되어 시간에 따른 동결영역확대로 폐기물 매립지 및 오염지역의 차폐를 위한 차수벽, 오염물질 흐름제어 등에 적용할 수 있을 것으로 판단된다.

• Journal of Biosystems Engineering
• /
• 제34권5호
• /
• pp.377-381
• /
• 2009

Excessive presence of heavy metals in environment may contaminate plants and fruits grown in that area. Rapid on-site monitoring of heavy metals can provide useful information to efficiently characterize heavy metal-contaminated sites and minimize the exposure of the contaminated food crops to humans. This study reports on the evaluation of a bismuth-coated glassy carbon electrode for simultaneous determination of cadmium (Cd) and lead (Pb) in a NIST-SRM 1568a rice flour by anodic stripping voltammetry (ASV). The use of a supporting electrolyte 0.1 M $HNO_3$ at a dilution ratio (sample pretreated with acid digestion in a microwave oven: supporting electrolyte) of 1:1 provided well-defined, sharp and separate peaks for Cd and Pb ions, thereby resulting in strongly linear relationships between Cd and Pb concentrations and peak currents measured with the electrode ($R^2\;=\;0.97$, 0.99 for Cd and Pb, respectively). The validation test results for spiked standard solutions with different concentrations of Cd and Pb gave acceptable predictability for both spiked Cd and Pb ions with mean prediction errors of 6 to 30%. However, the applicability of the electrode to the real rice flour sample was limited by the fact that Cd concentrations spiked in the rice flour sample were overly estimated with relatively high variations even though Pb ion could be quantitatively measured with the electrode.

• 한국식생활문화학회지
• /
• 제3권1호
• /
• pp.89-93
• /
• 1988

국내 도시락 공장을 조사 분석하여 대량생산에 적합토록 그 문제점을 보완 개선했다. 특히 식품위생법과 건축법상의 공장허가 사항을 고려해서 3가지 면적별로 모델 도시락 공장을 설계하였다. 작업장은 하나의 개방공간에 배치된 기기류를 오염지역, 준청결지역, 청결지역으로 나누어 작업중의 2차오염 문제를 배제시켰고, 기기류는 밥급속냉각기, 냉장고 겸 냉각기를 설치하여 위생안전성을 부여했으며, 청결실에 멸균(집진)기를 설치하여 완제품의 초기 미생물 농도를 줄이고 2차오염 요인을 제거함으로써 위생적인 도시락 생산유통이 가능한 도시락 생산공장을 설계하였다.

• 한국토양환경학회지
• /
• 제4권3호
• /
• pp.77-84
• /
• 1999

본 논문에서는 고농도의 중금속 (납, 구리)으로 오염된 세 가지의 토양을 대상으로 sequential extraction 방법을 사용하여 토양과 중금속의 차이에 따른 결합 특성을 밝혀내고자 하였다. 고농도의 납과 구리로 오염된 토양을 형태별로 추출하였을 때 토양의 특성과 중금속의 종류에 따라 다른 결과를 보였다. 납은 문화동 토양에서는 Carbonate 형태가 37.7%로 가장 높았고 농토는 Amorphous Fe oxide 형태가 23.9%, 공단 토양에서는 Exchangeable 형태가 22.9%로 나타났다. 이에 비하여 구리는 세 가지 토양에서 공통적으로 Organically bound 형태가 농토에서 26.1%, 문화동 토양은 20.4%. 공단 토양에서는 24.1%로 높게 나타났고 Carbonate 형태와 Amorphous Fe oxide형태의 비율도 높게 나타났다. 또한 Crystallized Fe oxide 형태와 Residuals 형태도 납보다 높은 비율을 나타냄으로서 구리가 납보다는 토양과 강한 결합을 형성하는 것으로 생각된다. 이러한 토양과 중금속의 결합 특성은 오염 토양의 복원시 유용한 자료가 될 수 있다.