• Resources Recycling
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• v.17 no.5
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• pp.37-43
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• 2008

Stripping experiments of iron from the loaded Alamine336 by sulfurous, chloric and sulfuric acid solutions have been performed by varying the concentration of acid and stripping conditions. The stripping percentage of iron decreased with the increase of HCl and $H_{2}SO_4$ concentration, while that increased with the increase of $H_{2}SO_3$ concentration up to 3 M. Stripping temperature had adverse effect on the stripping percentage of iron in the stripping by $H_{2}SO_3$ solution, while the stripping percentage of iron by HCl solution increased with the increase of temperature. Stripping isotherm of iron by 0.1 M HCl and 0.1 M $H_{2}SO_4$ solution indicated that three and four stripping stages could result in a solution containing 0.05 M iron at an O/A ratio of 1/10 from the loaded Alamine336 phase where iron concentration was 0.5 M.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.293-301
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• 2009

Analytical results of a fixed concentration of Pb, Cd and Cr in the synthetic copper standard solution (RMs) for using the matrix no matched standard calibration curve at various wavelength by ICP showed that accuracy (140 $\sim$ 1,070% in case of Pb) is very poor at all wavelengths because of the Cu matrix effect. Analytical results of a fixed concentration of Pb, Cd and Cr in the different concentration solutions of Cu showed that found values were on the increase or decrease as the rate of a regular equation as the concentration of Cu was increased. Accuracies by the Cu matching method in the analysis of Pb, Cd and Cr in the synthetic copper standard solution (RMs) were higher than 99.9%.

• Resources Recycling
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• v.18 no.1
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• pp.30-37
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• 2009

Distribution diagram of Pt(IV), Pd(II), and Rh(III) in HCl solution was obtained as a function of HCl concentration from 0.001 to 10 M by considering complex formation reaction together with mass balance. When HCl concentration was higher than 0.1 M, most of Pt and Pd in HCl solution exist as $PtCl_6^{2-}$ and $PtCl_4^{2-}$. The concentration of HCl had a feat effect on the speciation of Rh(III). As HCl concentration increases from 0.1 to 10 M, the pedominant species changes from $PhCl_5^{2-}$ to $PhCl_6^{3-}$. Interaction parameters of $PtCl_6^{2-}$ and $PdCl_4^{2-}$ with hydrogen ion were evaluated from the solvent extraction data of Pt and Pd reported in the literature.

• Journal of the Korean Applied Science and Technology
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• v.14 no.3
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• pp.63-69
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• 1997

Micellization range and cmc for the dilute aqueous solution of sucrose monoesters, that is, sucrose monolaurate, sucrose monomyristate, sucrose monopalmitate, sucrose monostearate and sucrose monooleate were investigated by computer programming. The extreme of the curvature of ${\sigma}$(C) as a new suggested method to determine the cmc and the micellization range was accomplished with computer programming. The values of cmc and micellization range can be obtained by the extreme of the curve by direct processing of only a few experimental data. The values of cmc particulary was in good agreement with those deduced intuitively from the shape of experimental curves of ${\sigma}$(C).

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.200-200
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• 2021

하천은 용수공급, 관개, 친수활동, 산업활동 등 인간의 활동에 중요한 역할을 한다. 이에 따라 수질관리는 필수적이며 유기물, 중금속, 화학물질 등의 용존물질들은 수질문제에 직접적으로 영향을 미친다. 따라서 하천에서의 용존물질의 혼합 거동을 파악하기 위한 연구가 지난 수십년간 이루어지고 있다. 하천 흐름에 따른 오염물질의 이동 및 확산 거동을 예측하기 위하여 1차원 추적모형이 활용되는데, 그 중 하천저장대 모형(Transient Storage Model, TSM)은 자연하천의 복잡하고 불규칙한 수리·지형적인 특성을 단순하게 반영할 수 있다는 장점때문에 가장 많이 사용된다. 하지만 TSM은 매개변수에 대한 의존성과 불확도가 크며, TSM의 저장대에서의 농도분포에 대한 지수함수형태의 모델링이 하상간극수역(Hyporheic zone)에서의 저장대 특성을 반영하기에 구조적으로 부정확하다는 단점이 제기되고 있다. 최근 이러한 TSM의 단점을 보완하고 하천에서의 저장대 메커니즘을 보다 정확하게 구현하고자 체류시간분포(residence time distribution)를 이용한 확률론적 저장대 모델링 프레임워크가 등장하고 있다. 본 연구에서는 본류대와 저장대에서의 오염물질의 체류시간분포를 분리하여 해석하고 이를 전달함수(transfer function)를 이용한 합성곱으로 결합한 형태의 프레임워크를 적용하여 모델링하였다. 상기의 모형을 검증하기 위하여 2019년 감천의 4.85km 구간에서 추적자 실험을 실시하였다. 실험 당시 유량은 12.9 m³/s로 풍수기에 해당되며 평균 유속은 약 0.6 m/s로 측정되었다. 모형의 매개변수는 추적자 실험으로부터 최적화 기법을 통해 역모델링기법으로 결정하였다. 제안된 모형에 의한 모의 결과를 추적자 실험에서의 농도측정자료와 비교한 결과, 평균 0.988의 결정계수를 보여 매우 높은 정확도를 보이고 있음을 알 수 있었다. 저장대특성을 나타내는 농도곡선의 꼬리부에 대하여 같은 조건에서 1차원 이송-분산(ADE) 모형, TSM의 모의결과와도 비교한 결과 본 모형은 추적자 실험 농도측정 결과와 평균 0.195의 오차율을 보이며, 이는 ADE 모형과 TSM의 오차율인 14.03과 1.866에 비해 매우 정확한 것으로 나타났다.

• Analytical Science and Technology
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• v.21 no.1
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• pp.20-24
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• 2008

A chemiluminescence method has been developed to determine vitamin $P_1$ in aqueous solution which is based on the enhancement of the intensity of lucigenin using lucigenin-$H_2O_2$ as chemiluminogenic system. The effects of experimental parameters such as concentrations of lucigenin, pH and concentrations of $H_2O_2$ were studied. The present method allows the determination of vitamin $P_1$ over the range $7.5{\times}10^{-6}{\sim}5.0{\times}10^{-4}mol/L$. The detection limit was $5.7{\times}10^{-7}mol/L$. The relative standard deviation was 0.75 % for 10 determinations of $7.5{\times}10^{-5}mol/L$ vitamin $P_1$. The correlation coefficient of the working curve was 0.9984 (S/N=3).

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.5
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• pp.356-362
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• 1999

Based on the assumption that film density increases exponentially with exposure in the industrial radiographic film. an equation representing the characteristic curves of industrial radiographic films and a new density-thickness relation are suggested. The accuracy and reliability of the suggested relation has been tested using radiographs of a carbon steel step wedge with known thickness variation by polychromatic X-ray and ${\gamma}$-ray ($Ir^{192}$). The experimental results were well agreed to the proposed relation in the range of film densities from 1.0 to 3.5 and it was more accurate than the conventional relation. It is also found that ${\gamma}$-ray is more effective in this purpose than polychromatic X-ray, which results in variation of effective linear absorption coefficient due to beam hardening effect as thickness increases. Therefore using the equation and experimentally determined parameters the quantitative evaluation of thickness variation is possible and it can be used to evaluate the depth of local corrosion of pressure vessels in plants.

• The Journal of Engineering Geology
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• v.16 no.3 s.49
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• pp.245-254
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• 2006

Using a natural gradient tracer test, the characteristics of hydrodynamic dispersion according to each depth of a fractured rock were studied, and the effective porosity and longitudinal dispersivity of the fractured rock were estimated. The difference of vertical hydrodynamic dispersion was identified by concentration breakthrough curves linear regression analyses of bromide concentrations according to depths versus time, and hydraulic fracture characteristics at two intervals of the monitoring well. Higher concentration and faster arrival time at GL- 18 m depth (RQD 13%, average joint spacing 2 cm, TCR 100%) than at GL- 25 m depth (RQD 41%, average joint spacing 7 cm, TCR 100%) resulted from shorter distance and more fractures. Tracer was transported through the 1 st fractures until the arrival of its peak concentration and through the 2nd fractures or matrix diffusion after the arrival of its peak concentration. The increase/decrease slopes of bromide concentration versus time were 3.46/-1.57 at GL-18 m depth and 3.l9/-0.47 at GL- 25 m depth of the monitoring well. So the faster bromide transport was confirmed at GL- 18 m depth with more fractures. The concentration increment of bromide was fitted by a Gaussian function and the concentration decrement of bromide was fitted by an exponential function. Effective porosity and longitudinal dispersivity estimated by CATTI code were 10.50% and 0.85 m, respectively.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.5
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• pp.112-122
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• 1999

이 논문은 일정체적을 갖는 양단고정 변단면 기둥의 좌굴하중 및 후좌굴 거동에 관한 연구이다. 기둥의 변단면으로는 직선형, 포물선형, 정현의 선형을 갖는세 가지 변단면을 채택하였다. Bernoulli-Euler 보 이론을 이용하여 압축하중이 작용하여 좌굴된 기둥이 정확탄성곡선을 지배하는 미분방정식을 유도하였다. 유도된 미분방정식을 Runge-Kutta 법과 REgula-Falsi법을 이용하여 수치해석하였다. 수치해석의 결과로 좌굴하중, 좌굴기둥의 평형경로 및 정확탄성곡선을 산출하였다. 또한 좌굴하중-단면비 곡선으로부터 최강기둥의 좌굴하중과 단면비를 산출하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.448-449
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• 2008

HIT(Heterojunction with intrinsic thin layer) solar cell은 결정 실리콘 (c-Si)을 n-type으로 제작시 수율이 어렵고 결정 실리콘 (c-Si)을 p-type위에 제조하는 것이 보다 보편적인 방법이므로 베이스의 결정 실리콘에는 p-type을, 그 위에는 진성 층(intrinsic layer) 그리고 반투명 전극의 아래에 제조되는 비정질 실리콘 (a-Si)을 n-type으로 하여 베이스 층과 TCO 후면 층의 두께, 도핑 농도 (doping concentration)와의 관계를 확인하여 본다.