• 분석과학
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• 제9권3호
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• pp.221-234
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• 1996

흔적량 금속이온인 Ag(I), Pd(II), Au(III) 및 Pt(IV)의 dibenzylammonium dibenzyldithiocarbamate(DBADBDC) 착물을 용매추출하기 위한 기초적인 연구를 수행하였다. 클로로포름으로 리간드 및 금속착물을 추출하기 위한 pH의 영향을 조사한 결과, DBADBDC는 pH 2~9에서 일정하게 추출되었으며 금속착물의 경우 Ag(I)는 산성용액에서, Pd(II) 는 pH 4 이상에서, Au(III)는 모든 pH 영역에서, Pt(IV)는 pH 3 이상에서 일정하게 추출되었다. 금속-DBDC 착물의 수용액과 용매간 분배 및 추출평형에서 분포비와 추출률은 Ag(I)의 경우 pH 0에서 log D=4.226 : E(%)=99.9%, Pd(II)는 pH 4~7에서 log D=1.804 ; E(%)=98.5%, Au(III)는 pH 2~10에서 log D=3.755: E(%)=99.9%, Pt(IV)는 pH 8에서 log D=0.165 : E(%)=57.2%의 최대값을 나타내었다. 몰비법으로 금속이온과 리간드가 착물을 형성할 때의 결합비를 조사해 보았다. Ag(I)는 1 : 1, Pd(II), Au(III) 및 Pt(IV)는 1 : 2의 착물을 형성하였으며, Au(III) 와 Pt(IV)는 착물내에 염화이온이 포함되어 있었다. 수용액에 염화이온이 존재할 때의 금속-클로로 착물의 추출반응을 규명할 수 있었으며, 각 금속이온을 착화제인 DBADBDC로보 추출할 때 각각의 추출반응과 상수식을 얻을 수 있었다.

• 한국전산응용수학회:학술대회논문집
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• 한국전산응용수학회 2003년도 KSCAM 학술발표회 프로그램 및 초록집
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• pp.9-9
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• 2003

Let $\Omega$ be a bounded, open, and polygonal domain in $R^2$ with re-entrant corners. We consider the following Partial Differential Equations: $$(I-\nabla\nabla\cdot+\nabla^{\bot}\nabla\times)u\;=\;f\;in\;\Omega$$, $$n\cdotu\;0\;0\;on\;{\Gamma}_{N}$$, $${\nabla}{\times}u\;=\;0\;on\;{\Gamma}_{N}$$, $$\tau{\cdot}u\;=\;0\;on\;{\Gamma}_{D}$$, $$\nabla{\cdot}u\;=\;0\;on\;{\Gamma}_{D}$$ where the symbol $\nabla\cdot$ and $\nabla$ stand for the divergence and gradient operators, respectively; $f{\in}L^2(\Omega)^2$ is a given vector function, $\partial\Omega=\Gamma_{D}\cup\Gamma_{N}$ is the partition of the boundary of $\Omega$; nis the outward unit vector normal to the boundary and $\tau$represents the unit vector tangent to the boundary oriented counterclockwise. For simplicity, assume that both $\Gamma_{D}$ and $\Gamma_{N}$ are nonempty. Denote the curl operator in $R^2$ by $$\nabla\times\;=\;(-{\partial}_2,{\partial}_1$$ and its formal adjoint by $${\nabla}^{\bot}\;=\;({-{\partial}_1}^{{\partial}_2}$$ Consider a weak formulation(WF): Find $u\;\in\;V$ such that $$a(u,v):=(u,v)+(\nabla{\cdot}u,\nabla{\cdot}v)+(\nabla{\times}u,\nabla{\times}V)=(f,v),\;A\;v{\in}V$$. (2) We assume there is only one singular corner. There are many methods to deal with the domain singularities. We introduce them shortly and we suggest a new Finite Element Methods by using Singular representation for the solution.

• Journal of Pharmaceutical Investigation
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• 제24권4호
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• pp.233-243
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• 1994

Precipitation was formed during the preparation of decoction from a mixture of Scutellariae Radix and Coptidis Rhizoma or Phellodendri Cortex according to the prescription of Hwang-ryean-hae-dog-tang. Baicalin and berberine were identified in coprecipitated product and these components were the active ingredients of two herbal medicine. The coprecipitated product was very slightly soluble in water and sparingly soluble in ethanol. The stoichiometric ratio of baicalin and berberine was found to be 1:1. The lipid-water partition coefficients of coprecipitated product were increased more than baicalin and berberine in chloroform, but were decreased in other organic solvents. The content of baicalin and berberine in coprecipitated product, determined by HPLC, were 23.08% and 26.75%, but the content of active ingredients in supernatant were 0.66% and 0.26%, respectively. The dissolution profile of baicalin of coprecipitated product was increased more than extract of Scutellariae Radix in artificial gastric juice, but was decreased in artificial intestinal juice. The dissolution rate of berberine of coprecipitated product was lower than extract of Coptidis Rhizoma in artificial gastric juice and intestinal juice commonly.

• Environmental Analysis Health and Toxicology
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• 제16권3호
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• pp.133-137
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• 2001

Acetanilide is a High Production Volume Chemical, which is produced about 2,300 tons/year in Korea as of 1998 survey. Most is used as an intermediate for synthesis of pharmaceuticals and dyes and the chemical is one of seven chemicals of which human and environmental risks are being assessed by National Institute of Environmental Research under the frame of OECD SIDS program. The chemical is water soluble (4 g/1 at 20$\^{C}$) and readily biodegradable (68.7％). Partition coefficiency (Log Pow) is 1.16 at 23$\^{C}$ so that the chemical has a low potential for bioaccumulation. The acute toxicities of algae, daphnia and fish are not high. The 72 hr-EｂC50 of algae is 13.5 mg/1,48 hr-EC50 of daphnia is over 100 mg/1 and 96 hr-LC50 of Oryzias latipes is over 100mg/1. Regarding the exposure, levels in air, water, soil or sediment have not been monitored or estimated so that risk evaluation of acetanilide was not possible. In this study, distribution of the chemical among environmental media was estimated using EQC model based on the chemical-physical properties. In Level I and IIof which the chemical are hypothesized in equilibrium and no transfer through the media, more than 98％ of acetanilide are estimated to be distributed in water. However, in Level Ⅲ of which non-equilibrium and intermedia transfer could be occurred, the chemical is estimated to distributed to soil as 51.8％ and water as 47.8％ as of total amount.

• 한국정보과학회논문지:시스템및이론
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• 제27권3호
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• pp.287-299
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• 2000

본 논문에서는 양방향 토러스 네트워크와 웜홀 라우팅을 사용하는 다중컴퓨터에 대해 멀티캐스트 통신방법을 트리방식, 경로방식, 그리고 두 방식을 조합한 하이브리드방식으로 분류하였다. 경로방식으로는 동적분할 멀티캐스트 라우팅 알고리즘을 제안하였으며, 하이브리드방식으로는 라우팅의 첫 단계로 트리방식을 사용하고 두 번째 단계로는 경로방식을 사용하는 멀티캐스트 라우팅 알고리즘을 제안하여 성능을 분석하였다. 세가지 멀티캐스트 라우팅 알고리즘간의 성능은 메세지 길이에 따른 평균 지연시간을 사용하여 비교하였다. 그리고 웜홀 라우팅에서 플릿 버퍼 크기의 변화에 따른 성능을 가상 컷-스루와 비교 하였으며, 경로방식의 알고리즘을 사용하여 버퍼 크기의 변화에 따른 지연시간을 기준으로 두 스위칭 방식의 성능관계를 분석하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제10권3호
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• pp.284-288
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• 1997

Purified diets containing five graded levels of tryptophan were fed to growing chicks to evaluate tryptophan requirements for growth and maintenance. A model was developed to separate tryptophan requirement for maintenance from requirement for growth. From this model, the daily tryptophan requirement for growth was 2.16 mg/g gain, and the daily requirement for maintenance 0.029 times metabolic body size ($Wg^{0.75}$). Based on nitrogen gain response, the tryptophan requirement for growth was 0.078 mg/mg N gain, and the daily maintenance requirement was 0.029 times metabolic body size. The total tryptophan requirements were 71.56 mg/day or 0.173% of the diet, 69.48 mg/day or 0.168% of the diet based on the weight gain response and nitrogen gain response, respectively. Previous tryptophan requirements for growing chicks aging 1-28 days are in close agreement with these estimates. Based on the relationship of weight gain and N gain, about 1.25% of the retained CP was consisted of tryptophan; the previously reported value of tryptophan content of chick muscle CP was 1.03%.

• Asian-Australasian Journal of Animal Sciences
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• 제10권3호
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• pp.277-283
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• 1997

Purified diets containing five levels of methionine with 0.4% cystine were fed to growing chicks (8 days old male Arbor Acre strain) to evaluate methionine requirements for growth and maintenance. A model was developed to separate methionine requirement for maintenance from requirement for growth. From this model the daily methionine requirement for growth was 4.22 mg/g gain, and the daily methionine requirement for maintenance was 0.034 times metabolic body size ($W^{0.75}$). Based on nitrogen gain response, the methionine requirement for growth was 0.162 mg/mg N gain, and the daily maintenance requirement was 0.037 times metabolic body size. The plateau of plasma methionine concentration reached at 117.16 mg intake pre day. The total methionine requirement determined based on weight gain response was 138.29 mg/day or 0.33% of the diet and the one determined based on nitrogen gain response was 141.7 mg/day of 0.34% of the diet, respectively. As a percentage of protein, methionine was calculated to be 2.6%; the reported methionine content of carcass CP was 1.76%.

• Journal of Advanced Marine Engineering and Technology
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• 제21권4호
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• pp.372-380
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• 1997

This paper describes experimental investigations of helium-air exchange flows through parti¬tioned opening and two-opening. Such exchange flows may occur following rupture accident of stand pipe in high temperature gas cooled reactor. A test vessel with the two types of small open¬ing on top of test cylinder is used for experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. In the case of exchange flow through the partitioned opening, flow passages of upward flow of the helium and downward flow of the air within the opening are separated by vertical partition, and the two flows interact out of entrance and exit of the opening. Therefore, an experiment of the exchange flow through two-opening is made to investigate effect of the fluids interaction of the partitioned opening sys¬tem. As a result of comparison of the exchange flow rates between the two types of the opening system, it is found that the exchange flow rate of the two-opening system is larger than that of the partitioned opening system due to absence of the effect of fluids interaction. Finally, the fluids interaction between the upward and downward flows through the partitioned opening is found to be an important factor on the helium-air exchange flow.

• 분석과학
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• 제8권4호
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• pp.511-517
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• 1995

A cationic water soluble porphyrin (5,10,15,20-tetrakis (l-methyl-pyridinium-4-yl)porphyrin, $H_2tmpyp^{4+}$) and its metalloporphyrins (MP) were easily extracted into acetonitrile separated by addition of sodium chloride ($4mol\;dm^{-3}$) in the presence of sodium perchlorate, where M denotes $Zn^{2+}$, $Cu^{2+}$, $Co^{3+}$, $Fe^{3+}$, and $Mn^{3+}$ and $P^{2-}$ is porphyrinate ion. The extracted ion-pair complexes were completely dissociated to $[MP(ClO_4)_3]^+$, and $[MP(ClO_4)_2]^{2+}$. The extraction and the dissociation constants were determined by taking into account of the partition constant of sodium perchlorate ($K_D=1.82{\pm}0.01$). The chemical properties of the separated acetonitrile phase as $E_{T(30)}$ and $D_{II,I}$ were determined and compared with other water miscible solvents (acetone, actonitrile, 1,4-dioxane, tetrahydrofuran, 1-propanol and 2-propanol). Furthermore, a sensitive and selective method was proposed for the determination of a subnanogram amount of copper(II) in natural water samples by using the present salting-out method and the porphyrins.

• Corrosion Science and Technology
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• 제16권4호
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• pp.161-166
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• 2017

The qualitative composition of active components of the corrosion inhibitor CGW-85567 was studied. It was found that С18:2 and С18:1 imidazolines and the corresponding imidazolin-amides are the major components. The HPLC/MS technique was developed for their determination in the water solutions of monoethylene glycol (MEG). Industrial application of the inhibitor showed that MEG solution retained high concentration of the inhibitor for a long time after ceasing its addition into pipelines. Low values of the partition coefficients (0.010-0.014) of imidazolines in the system "water solution of MEG (concentration of MEG 62-85% v/v) - gas condensate" have allowed to pass on from the technology of continuous pumping of the inhibitor into protected pipelines to the periodic dosing technology. Taking into account a long time of circulation in the system and high temperatures during MEG regeneration process possible degradation products of the inhibitor were studied. N, N-dimethyl-dodecanamine-1, and N, N-dimethyl-tetradecanamine-1 were identified as major degradation products of the corrosion inhibitor CGW-85567.