• 한국환경보건학회지
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• 제43권5호
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• pp.393-400
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• 2017

This study was investigated on pH, heavy metals, oils and solvents in 34 surface soil samples and the samples are collected at two times for 17 farmland sites around 7 industrial areas in Northern Gyeonggi Province. As a result of pH for soil contamination monitoring network, the range of pH showed 4.4~8.4 and average was 6.3. The range of pH for Agricultural land around industrial area was 6.7~7.5 and average indicated 7.1 that mostly showed neutral condition in this area. he average concentrations of Cu, Pb, Ni, As and $Cr^{6+}$ are lower than Korea soil contamination worrisome levels at region 1 and the mean levels of farmland from the soil quality monitoring network. The average concentrations of Zn, Cd and Hg didn't exceed the soil contamination worrisome levels at region 1 but slightly higher than the mean levels of farmland from the soil quality monitoring network. The heavy metal levels of all samples are within Korea soil contamination worrisome levels at region 1. The results showed that the detected heavy metal concentrations ranged from N.D. to ~32.7% of Korea soil contamination worrisome levels at region 1. BTEX, TPH, TCE and PCE were not detected in all samples and thus the farmland around the industrial areas were free from oils and solvents contamination.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.720-725
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• 2011

금속질산염과 염화금산을 전구체로 사용하여 다양한 금속산화물($$Al_{2}O_{3}$, ZnO, $Fe_{2}O_{3}$, $Cr_{2}O_{3}$, $MnO_{2}$, CuO, NiO, $Co_{3}O_{4}$)에 담지된 금촉매를 공침법을 이용하여 제조한 후, 일산화탄소 산화반응에서 수분첨가의 영향을 검토하였다. 이들 중 $Co_{3}O_{4}$와 ZnO에 담지된 금촉매가 일산화탄소에 대하여 높은 활성을 보여주었다. 반응가스 중에 수분이 첨가될 때 Au/$Co_{3}O_{4}$ 촉매는 활성이 약간 감소하였으나, Au/ZnO 촉매에서는 활성이 크게 증가하여 수분에 의한 일산화탄소 산화 활성은 담체의 종류에 크게 의존함을 알 수 있었다. 반응가스 중에 포함된 수분에 관계없이 반응 전과 후의 Au(5 wt%)/ZnO 촉매의 금입자 크기는 거의 변하지 않아 활성이 감소되는 이유는 금입자들의 소결에 의한 영향보다는 카보네이트와 같은 화학종에 의해 불활성화가 일어남을 알 수 있었으며, 이 화학종은 수분의 첨가에 의해 이산화탄소로 분해되어 활성이 증가한 것으로 생각된다.

• 한국결정성장학회지
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• 제6권1호
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• pp.88-97
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• 1996

태양전지의 전극형성은 전지의 가격과 성능 그리고 시스댐의 신뢰성을 결정하는데 매우 중요한 변수이다. 기폰의 스크련 프린팅 기술은 전면전극에 냐쁜 영향을 미치는 여러가지 제약들을 가지고 었다. 전극함몰형 태양전지는 기존의 전극에서 발생하는 문제점을 극복하고 저가격 대량생산을 위해서 고안된 것이다. 본 논문에서는 무전해 도금방법을 사용하여 함몰형 전지의 전극을 형성하는 공정을 최적화함으로써 값싸고 재현성있게 전지를 제조할 수 있었다. 무전해 도금용액으로는 상엽적으로 사용되는 니켈, 구리, 은 용액을 사용하었으며, 전지의 효울 을 최고 18.8 %까지 얻었다. 이때 전지의 개방전압은 651 mV, 단락전류밀도는 37.1 mA/$\textrm{cm}^2$, 충실도는 77.8 % 었으며 배치에서 90 % 이상의 전지가 18 % 이상의 효율을 나타내었다.

• 천문학회보
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• 제36권1호
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• pp.27.1-27.1
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• 2011

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 25 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the elemental abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 25 elements, such as C, N, O, S, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu by EW measurements, and the S abundances were estimated using synthetic spectrum. We have found that [Mg/Fe] and [Al/Fe] for planet host stars have lower limit comparing with those of comparison stars, and [Ca/Fe] of host star with Neptunian planets is relatively lower than the other host stars with massive planets. We have performed the Kolmogorov-Smirnov test, and examined the ratio of planet host stars to all stars for each bin of [X/H]. As a result, we noted that the O, Si, and Ca abfor undances are strongly related with the presence of planets.

• 한국환경과학회지
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• 제24권8호
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• pp.969-980
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• 2015

In order to certificate the distribution and pollution of heavy metal of surface sediments in Nakdong River were collected and analyzed for grain size, water content, ignition loss and heavy metal content. Surface sediments mainly composed of sand(avg. 94.6%) and water content and ignition loss were 20.46%, 1.53% on average. Grain size were relatively fine and organic matter content were relatively high in the Hoichun and Sunakdonggang. Most of heavy metal content(Zn > Cr > Pb > Ni > Cu > Hg) in the Deokcheongang and Sunakdonggang were higher than the other streams. The Igeo were non polluted(less than 0) in all streams and the EF were relatively high in the small stream and PLI were non polluted(less than 1). In addition, organic matter, heavy metal content and pollution were highly correlation with grain size. Surface sediments in study area, heavy metal pollution of the Sunakdonggang were relatively high compared to the other stream but these results were not serious pollution that exceed the sediment pollution evaluation standard of river and lake in Korea and pollution levels adversely affected the majority of benthos were not.

• Advances in environmental research
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• 제2권2호
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• pp.155-166
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• 2013

A preliminary investigation to establish the status of contamination of trace metals in the Western coast of Ghana was conducted prior to the commercial production of crude oil in the area. The study revealed the presence of heavy metals such as Pb (4.00-79.64 mg/kg), As (8.81-236 mg/kg), Cu (12.86-108.06 mg/kg), V (28.07-953.32 mg/kg), Zn (7.08-264.25 mg/kg), Cr (101.69-1366.62 mg/kg), Ni (42.41-451.43 mg/kg), Mn (16.77-1890.45mg/kg), Br (7.66-142.78 mg/kg), Ti (542.03-19960 mg/kg) and Fe (7472.88-97120 mg/kg) at six sites sampled along the coast. With the exception of Ti and Fe which showed no variation in metal concentration, the rest of the metals varied significantly among the sampled locations. Potential ecological risk of metals particularly of Co, As and Br which exhibited extreme enrichment of the sediments indicates considerable metal pollution in the studied areas. The degree of contamination is of particular concern especially to benthic biota that inhabit this environment for survival.

• 한국분말재료학회지
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• 제14권4호
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• pp.230-237
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• 2007

The fabrication of Fe alloy-40 wt.%TiC composite materials using spark plasma sintering process after ball-milling was studied. Raw powders to fabricate Fe alloy-TiC composite were Fe alloy, $TiH_{2}$ and activated carbon. Fe alloy powder was Distaloy AE (4%Ni-1%Cu-0.5%Mo-0.01%C-bal.%Fe) made by Hoeganes company with better toughness and lower melting point. These powders were ball-milled in horizontal attrition ball mill at a ball-to-powder weight ratio of 30 : 1. After that, these mixture powders were sintered by using spark plasma sintering apparatus for 5 min at $1200-1275^{\circ}C$ in vacuum atmosphere under $10^{-3}$ torr. DistaloyAE-40 wt.%TiC composite was directly synthesized by dehydrogenation and carburization reaction during sintering process. The phase transformation of as-milled powders and sintered materials was confirmed using X-ray diffraction (XRD) and transmission electron microscope (TEM). The density and harness materials was measured in order to confirm the densification behavior. In case of DistaloyAE-40 wt.%TiC composite retained for 5 min at $1275^{\circ}C$, it has the relative density of about 96% through the influence of rapid densification and fine TiC particle reinforced Fe-based composites materials.

• Journal of Microbiology and Biotechnology
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• 제22권10호
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• pp.1388-1394
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• 2012

A xylanase-producing thermophilic strain, Geobacillus sp. TC-W7, was isolated from a hot spring in Yongtai (Fuzhou, China). Subsequently, the xylanase gene that encoded 407 amino acids was cloned and expressed. The recombinant xylanase was purified by GST affinity chromatography and exhibited maximum activity at $75^{\circ}C$ and a pH of 8.2. The enzyme was active up to $95^{\circ}C$ and showed activity over a wide pH range of 5.2 to 10.2. Additionally, the recombinant xylanase showed high thermostability and pH stability. More than 85% of the enzyme's activity was retained after incubation at $70^{\circ}C$ for 90 min at a pH of 8.2. The activity of the recombinant xylanase was enhanced by treatment with 10 mM enzyme inhibitors (DDT, Tween-20, 2-Me, or TritonX-100) and was inhibited by EDTA or PMSF. Its functionality was stable in the presence of $Li^+$, $Na^+$, and $K^+$, but inhibited by $Hg^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Pb^{2+}$, $Fe^{3+}$, and $Al^{3+}$. The functionality of the crude xylanase had similar properties to the recombinant xylanase except for when it was treated with $Al^{2+}$ or $Fe^{2+}$. The enzyme might be a promising candidate for various industrial applications such as the biofuel, food, and paper and pulp industries.

• 한국환경농학회지
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• 제34권1호
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• pp.64-68
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• 2015

BACKGROUND: Heavy metals (Al, As, Cd, Cr, Cu, Li, Hg, Ni, Pb, and Zn) were analyzed to elucidate the impact of weir construction on their concentrations in sediments of Geum River, Korea. We also attempted to investigate the source of the heavy metals in sediments. METHODS AND RESULTS: For this study, sediments were collected from May through June in 2012. The concentrations of heavy metals except Hg were determined by inductively coupled plasma mass spectrometer, and Hg was measured by automatic mercury analyzer. More clay were accumulated in the furthest stations in the upstream direction starting from the weirs. Most of the heavy metals showed higher concentrations in the most upstream located station of Geumnam Weir. However, high concentrations were not observed in the most upstream stations of the other weirs. The concentrations of Hg and As were much higher in sediments of Gap Stream. CONCLUSION: Gap Stream may be a potential source for high deposits of As and Hg. Presence of the dams may not play an important role in controlling heavy metal concentrations in sediments. It is necessary to monitor heavy metal concentrations for a longer time period to study the effect of environmental changes on heavy metal distribution in Geum River.

• 분석과학
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• 제15권6호
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• pp.496-501
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• 2002

Electrolyte cathode atomic discharge (ELCAD)는 용액 중에 포함된 미량 중금속을 연속 자동적으로 측정하기 위한 새로운 광학 측정기로서 플라스마에 의한 중금속들의 방출 강도를 측정하는 원자방출 분광법의 하나이다. 특히 이 방법은 검액을 전처리하지 않고 직접 분석할 수 있기 때문에 온라인 (on-line) 현장분석이 가능하다. ELCAD에서는 분위기 가스로 공기를 이용하고, 양극부분에 백금 전극을 사용하며, 음극에서는 연속적으로 전해질 시료를 주입하면서 플라스마를 형성하면서 미량의 중금속을 분석할 수 있다. 액상 글로우 방전의 기초 특성 연구로는 철의 원자 방출선 세기를 구한 다음 Einstein-Boltzmann식을 사용하여 플라스마 온도를 구한 다음 구리, 납, 철 및 니켈의 미량 분석 및 간섭 현상에 대해서 연구하였고, 검출 한계를 구하였다.