• 한국산업보건학회지
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• 제11권3호
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• pp.212-218
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• 2001

This study was performed to estimate environmental and biological monitoring of workers exposed to methyl bromide through quarantine fumigation. Airborne methyl bromide and it's metabolites were analyzed by gas chromatography and ion chromatography, respectively. The results are as followings; airborne concentration of methyl bromide(TWA) was $2.08{\pm}1.56ppm$(N=8). Dispersion and setting/degas groups were $0.67{\pm}0.12ppm$(N=2) and $2.54{\pm}1.53ppm$(N=6), respectively. Bromide ion concentration in serum was $23.40{\pm}14.91mg/{\ell}$(N=10) in the exposed workers and $4.74{\pm}0.82mg/{\ell}$(N=21) in the non-exposed workers. Bromide ion concentration in urine was $35.56{\pm}26.89mg/{\ell}$(N=11) in exposed group and $6.62{\pm}2.31mg/{\ell}$(N=21) in non-exposed group. Good correlation was observed between concentration of serum and urine ($r^2$=0.890 p<0.01). No significant correlations of other determinants were observed. Calculated from a regressive curve, the biological half lifes of serum and urine were 10.7 and 5.9 days. In these results, biological monitoring of bromide ion of serum and urine provided useful information for evaluating exposure of workers to methyl bromide, so that an availability of bromide ion of biological samples was showed as biological monitoring indices for methyl bromide.

• 한국습지학회지
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• 제11권3호
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• pp.37-47
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• 2009

본 연구지역은 전라남도에 위치한 고흥만 간척지 내 인공습지이며, 인공습지수와 주변 유입수의 수질특성을 파악하기 위해 2008년 3월 15일 및 2009년 1월 10일에 12개 지점에서 현장조사를 수행하였다. 수온, pH, DO, EC 및 salinity 항목은 현장측정 되었으며, 채수된 시료는 실내에서 TOC, Cl-, COD, TSS, T-P 및 T-N 성분을 분석하였다. 현장 관측된 5개 항목은 인공습지에 비해 유입지점들에서 높게 나타났으며, 이는 주변 농경 작지에서 유입되는 오염물질에 의한 것이다. 인공습지수와 유입수 내 농도비는 TOC 성분은 1월에, Cl 성분은 3 월에 더욱 높은 값을 보였다. COD 성분은 인공습지수에 대한 유입수의 농도비가 1.37배와 1.49배로서 유사하였다. 유입지점들에서 T-P와 T-N 성분의 평균값은 인공습지 내에서보다 3배 이상 높았으며, 인공습지의 자정능력에 의해 농도가 저감되었다. 본 연구지역의 인공습지에서는 유입수 내 Cl, T-P, T-N 성분의 정화효율이 높은 것으로 나타났다. Cl- 성분의 정화효율은 1차 관측 시 83%, 2차 관측 시 76% 이었으며, 이는 인공습지수에 의한 희석효과에 의한 것이다. T-P 성분의 정화효율은 67%(1차 관측)와 69%(2차 관측), T-N 성분은 100%(1차 관측)와 95%(2차 관측) 로서 매우 높았다. 본 연구에서 T-N의 정화효율이 비현실적으로 높은 것은 유입수의 양이 소량이어서 인공습지수 내에서는 질소 농도가 분석한계 이하로 나타났기 때문이다. 본 연구에서는 T-P 성분의 정화효율이 1월에, T-N 성분은 3월에 높게 나타나 생장기와 동절기의 영향에 의한 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.509-512
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• 1987

We report that the optimum substrate temperature to fabricate a-Si:H $n^+-p-p^+$ cell decreases with increasing the boron concentration in the Player. The results can be explained as the dependence of substrate temperature for the relaxation of silicon atoms and the bonded hydrogen concentration in the player.

• 환경위생공학
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• 제17권2호
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• pp.63-70
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• 2002

We investigated the concentration degree of VOCs for ambient air in the air environment control area of Kyonggi-do in 2001. The VOCs showing higher concentration were in the ascending order of Toluene > n-Butane > 1-Butene > Benzene > n-Hexane. The concentration distribution ratio mentioned above showed almost same pattern in each city. The relative concentration ratio of Benzene, Toluene, Ethylbenzene, Xylenes which are aromatic VOCs were 1 : 6.3 : 0.6 : 1.6. It was similar to the pattern in 1999 but different from the pattern in 2000. In the aspect of seasons, the highest B.T.E.X concentration was indicated in fall and in the aspect of areas, the higher concentration showed in the ascending order of Buchon > Ansan > Kwangmyong > Shihung > Sungnam. The average concentration of target VOCs for ambient air in the air environment control area of Kyonggi-do showed lower concentration than the metropolis of Seoul but higher concentration than Kwang-ju city and Dae-gu city. The amount of total VOCs was increasing, comparing with it last year and the more increasing tendency is anticipated so that it will need to establish the proper regulative criteria.

• 한국환경과학회지
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• 제17권5호
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• pp.509-516
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• 2008

New functional surfactant, N,N-dimethyl-N-dodecyl-N-(2-methyl benzimidazoyl) ammonium chloride(DDBAC) having benzimidazole(BI) functional group have been synthesized and the critical micellar concentration of DDBAC measured by surface tentiometry and electric conductivity method was $8.9{\times}10^{-4}M$. Micellar effects in DDBAC functional surfactant solution on the hydrolysis of p-nitrophenylacetate(p-NPA), p-nitro-phenylpropionate(p-NPP) and p-nitrophenylvalerate(p-NPV) were observed with change of various pH (Tris-buffer). The pseudo first rate constants of hydrolysis of p-NPA, p-NPP and p-NPV in optimum concentration of DDBAC solution increase to about 160, 280 and 600 times, respectively, as compared with those of aqueous solution at pH 8.00(Tris-buffer). It is considered that benzimidazole functional moiety accelerates the reaction rates of hydrolysis because they act as nucleophile or general base. In optimum concentration of DDBAC solution, the rate constants of hydrolysis of p-NPP and p-NPV increase to about 1.5 and 3.0 times, respectively, as compared with that of p-NPA. It means that the more the carbon numbers of alkyl group of substrates, the larger the binding constants between DDBAC micelle and substrates are. To know the hydrolysis mechanism of p-NPCE(p-NPA, p-NPP and p-NPV), the deuterium kinetic isotope effects were measured in $D_2O$ solutions. Consequently the pseudo first order rate constant ratios in $H_2O$ and $D_2O$ solution, $k_{H_2O}/k_{D_2O}$, were about $2.8{\sim}3.0$ range. It means that the mechanism of hydrolysis were proceeded by nucleophile and general base attack in approximately same value.

• 한국표면공학회지
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• 제38권4호
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• pp.137-143
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• 2005

CrSiN coatings of stepwise changing Si concentration were deposited on stainless steel by closed field unbalanced magnetron sputtering (CFUBM) system. Microstructure of the films due to the Si concentration is measured by XRD. The corrosion behavior of CrSiN coatings in deaerated $3.5\%$ NaCl solution was investigated by potentiodynamic test, electrochemical impedance spectroscopy (EIS) and surface analyses. The microstructure of CrSiN film depends on the Si concentration. When Si/(Cr+si) was under $11.7\%$, preferred orientation is defined at CrN(220), CrN(311) and $Cr_2N(111).$ The results of potentiodynamic polarization tests showed that the corrosion current density and porosity decreased with increasing Si/(Cr+si) ratio. EIS measurements showed that the corrosion resistance of Si-bearing CrN was improved by phase transformation of the film, which leads to increase of pore resistance and charge transfer resistance. At the Si(Cr+si) ratio of 20, the Si-bearing CrN possesses the best corrosion resistance due to the highest pore resistance and charge transfer resistance.

• 한국초지조사료학회지
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• 제13권2호
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• pp.93-98
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• 1993

To determine the effects of potassium($K_2O$) fertilization level(0, 100, 200 and 300 kg/ha/year) on the growth, dry matter(DM) yield, nutritive value and nitrate nitrogen($NO_3$-N) concentration of grasses grown under shading condition, this experiment was carried out in Grassland Div., LES, 1989. The plants were sampled on different growing seasons (spring, summer and autumn) and growth stages (grazing and soiling), respectively. Shade was controlled artificially ca. 45-50%, and the level of nitrogen fertilization was 200 kg/ha/year in all treatments. Higher DM was produced in spring 1, 453 kg at grazing and 2, 364 kg/ha at soiling stage, and DM production was increased with increasing level of $K_2O$. In this experiment, the optimum amount of $K_2O$ fertilizer was 200 kg/ha. The neutral detergent fiber, acid detergent fiber, DM digestibility, and relative feed value of grasses were not affected by $K_2O$ fertilization, regardless of growing season and growth stage. The $NO_3$-N concentration of grasses grown in spring was very low (ca. 1.0%), regardless of growth stage and $K_2O$ level. However, $NO_3$-N concentration was very high in summer and autumn season, also $NO_3$-N was decreased significantly with increasing level of $K_2O$ fertilization (P<0.05). Application of $K_2O$ fertilizer, therefore, is thoughs to be desirable for reducing $NO_3$-N concentration of grasses, especially in summer and autumn season. So annual split fertilization of $K_2O$ could be recommended on woodland pasture.

• 한국지반환경공학회 논문집
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• 제12권2호
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• pp.55-61
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• 2011

NDMA(N-Nitrosodimethylamine)는 극저농도(10ng/L)에서도 암을 일으킬 수 있는 물질로 알려져 있지만, 기존의 NDMA 제거율 평가 연구는 고농도의 NDMA를 대상으로 한 것이 대부분이었다. 따라서 극저농도의 NDMA 제거효율 평가가 필요하며 그 기초연구로써 호기성/혐기성 조건에서의 분말활성탄, GS(Granular Sludge), MF(Microfiltration), UF(Ultrafiltration)를 이용한 제거효율과 Silica gel(MCM-41, Diatomite, Spherical silica gel)을 이용한 제거효율을 평가하였다. 그 결과 혐기성 조건에서 GS, PAC를 접촉한 후 UF membrane을 이용한 고액분리가 65%의 제거율로 가장 높았으며, Silica gel(MCM-41)이 6%의 제거율로 가장 낮았다. 본 연구는 극저농도의 NDMA 제거의 기초 연구로서 향후 관련 연구의 기초자료로써 활용을 기대한다.

• 한국토양비료학회지
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• 제45권6호
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• pp.943-948
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• 2012

오이 시설재배지에서 질소 시비량 절감에 대한 호밀 환원 효과와 수량과 토양용액 중 질산태질소와의 관계를 평가하였다. 시험 처리구는 토양검정시비구 (NPK), 호밀을 $42.3Mg\;ha^{-1}$ 환원하여 질소비료 199 kg N $ha^{-1}$의 0, 50, 75, 100%의 4 수준으로 시비하여 시설재배지에서 오이 수량과 토양용액의 질산태질소 농도를 조사하였다. NPK의 오이수량은 $68.8Mg\;ha^{-1}$이었고, 호밀의 투입은 토양검정 질소시비량의 25-50%를 절감할 수 있었다. 오이재배 기간 중 NPK 토양용액의 평균 $NO_3$-N 농도는 $32.4mg\;L^{-1}$ 이었고, 호밀처리구의 0, 50, 75, 100%에서는 각각 26.0, 30.1, 41.4, $58.5mg\;L^{-1}$으로 질소시비량이 증가함에 따라 높아졌다. 이때 시설재배 오이수량과 토양용액 중 평균 $NO_3$-N 농도와의 수식 ($Y=49.3+0.63X-0.0034X^2$, $R^2=0.778^{**}$)은 유의성을 나타내었다. 따라서 오이 재배 중 토양용액 분석으로 질소 웃거름 시비량 결정이 가능할 것으로 판단되었다. 그러나 오이수량과 토양용액 $NO_3$-N 농도와의 관계에 대한 추가적인 실증연구가 필요할 것으로 사료된다.

• 한국환경과학회지
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• 제9권5호
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• pp.429-436
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• 2000

In order to study on the variational characteristics of water quality and chlorolphyll a concentration the water samples were collected daily or three times a week during the period from April 1990 to November 1991 at Kukdong port located in the northern Kamak bay of Southern Korea I made an analysis on biological factor as chlorophyll a concentration as well as physico-chemical factors such as water temperature salinity sigma-t dissolved oxygen, nutrients (ammonia, nitrite, nitrate, phosphate, and silicate) N/P ratio and chemical oxygen demand. In Northern Kamak bay seasonal variations in physical factors such as water temperature salinity and sigma-t were very marked. On the other hand chemical factors such as nutrients concentration and COD were not so. Chemical factors, in particular silicate were influenced by input of freshwater. And the roles of silicate on the seasonal succession of phytoplankton species composition was very low. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round and it was controlled by the combination of several factors especially of N/P ratio determined by dissolved inorganic nitrogen.