• Macromolecular Research
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• 제16권2호
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• pp.155-162
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• 2008

We report the successful synthesis of poly(NBECOOH-b-NBEPOSS) copolymers, taking advantage of the sequential, living ring opening metathesis polymerization of NBETMS and NBEPOSS using the $RuCl_2(=CHPh)(PCY_3)_2$/$CH_2Cl_2$/$20^{\circ}C$ system, followed by the hydrolysis of trimethylsilyl groups in poly(NBETMS-b-NBEPOSS) copolymers. The living behavior of ROMP of NBETMS was first investigated using two diagnostic plots, a first order kinetic plot and a $\bar{M}_n$ vs. conversion plot. The plots confirmed that no termination and chain transfer reaction had occurred during polymerization. Poly(NBECOOH-b-NBEPOSS) copolymers were prepared using the sequential monomer addition of NBEPOSS to living poly(NBETMS) chain ends, followed by the hydrolysis of trimethylsilyl groups in the poly(NBETMS-b-NBEPOSS) copolymers. The high structural integrity of poly(NBE-COOH-b-NBEPOSS) copolymers was confirmed by $^1H$-NMR, $^{13}C$-NMR spcctroscopy and GPC.

• 대한수학회지
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• 제47권1호
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• pp.165-187
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• 2010

We introduce two numerical schemes for solving a system of ordinary differential equations which characterizes several kinds of linear reactions and diffusion from biochemistry, physiology, etc. The methods consist of sequential applications of the simple exact solver for a reversible reaction. We prove absolute stability and convergence of the proposed explicit methods. One is of first order and the other is of second order. Numerical results are included.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.121-127
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• 2006

It has become inevitable to search for alternative fuels due to severe energy crisis these days. Use of alternative fuels, which are typically of lower quality, tends to increase environmental pollution, including formation of nitrogen oxides (NOx). In this paper performance of vacuum residue has been investigated experimentally as well as numerically in typical operating conditions of a furnace. Heat release reaction is modeled as sequential steps of devolatilization, simplified gas phase reaction and char oxidation as that for pulverized coal. Thermal and fuel NOx are predicted by conditional estimation of elementary reaction rates and are compared against measured experimental data. On the overall reasonable agreement is achieved for spatial distributions of major species, temperature and NOx for all test cases.

• 대한핵의학회지
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• 제20권1호
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• pp.75-83
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• 1986

Various TSH RIA kit components were prepared. Conditions for $^{125}I$ labelling of h-TSH were optimized by diminishing the amount of chloramine-T, ertending reaction time and lowering reaction temperature. Yield, specific activity, and immunological activity could be maintained moderately under such mild reaction conditions. The mixture of polyethyleneglycol(PEG) and second antibody worked effectively as a B/F separation agent. Even though the mixture was made with more diluted PEG and second antibody than those of using the sole component separately, the tine required for the B/F separation was shorter in case of using the mixture. The sequential saturation technique was efficient than those of applying ordinary equilibrium saturation technique in assay sensitivity and assay precision points of view.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권4호
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• pp.257-262
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• 2003

A straightforward and effective method is presented for immobilizing enzymes on a microchip platform without chemically modifying a micro-channel or technically microfabricating a column reactor and fluid channel network. The proposed method consists of three steps: the reconstitution of a nitrocellulose (NC) membrane on a plane substrate without a channel network, enzyme immobilization on the NC membrane, and the assembly of another substrate with a fabricated channel network. As a result, enzymes can be stably and efficiently immobilized on a microchip. To evaluate the proposed method, two kinds of enzymatic reaction are applied: a sequential two-step reaction by one enzyme, alkaline phosphatase, and a coupled reaction by two enzymes, glucose oxidase and peroxidase, for a glucose assay.

• 항공우주기술
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• 제13권2호
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• pp.18-28
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• 2014

네 개의 반작용휠이 장착된 위성에 두 개의 우주검증용 제어모멘트자이로가 탑재되었다고 가정하고, 이들을 이용한 위성 고기동 방법에 대해서 연구해 보았다. 토크가 큰 제어모멘트자이로를 먼저 사용하여 위성의 자세오차를 줄인 후에, 반작용휠을 통해 나머지 자세오차를 제어하는 방법을 제안하였다. 본 방법을 사용할 경우, 제어모멘트자이로에서 발생하는 특이점 문제를 회피할 수 있으며, 토크 명령 계산시 김벌각 정보가 필요 없다는 장점이 있다. 또한 시뮬레이션을 통해, 본 방법이 기존에 연구된 방법들에 비해 위성의 기동성능에는 큰 차이가 없으며, 필요한 반작용휠의 모멘텀도 크게 줄어드는 것을 확인하였다.

• 한국지반환경공학회 논문집
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• 제2권3호
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• pp.17-35
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• 2001

본 연구에서는 자연점토에 납, 구리, 아연, 카드뮴의 단일 흡착 시 온도변화에 따른 흙의 구성성분별 흡착거동을 살펴보기 위해 혼합 흡착-연속추출법(combined adsorption-sequential extraction analysis, CASA)을 사용하였다. 실험결과 납과 구리의 경우 약 50%이상의 분배가 탄산염 형태로 나타났고, 카드뮴의 경우 약 80%이상의 분배가 이온교환 형태로 나타났다. 아연의 경우 $25^{\circ}C$이하의 온도에서는 이온교환 형태로의 분배가 약 60%로 나타났고, $40^{\circ}C$이상의 온도에서는 탄산염 형태로의 분배가 50%이상으로 나타났다. 흙의 각 구성성분에 대한 흡착용량의 온도에 따른 영향은 철.망간 산화물과 유기물 형태에서 주로 발생하는 것으로 나타났다. 또한 이온교환 형태를 제외한 모든 형태에 대한 중금속들의 흡착 반응은 온도의 증가에 따라 흡착량이 증가하는 흡열반응(${\Delta}H^0$ >0)인 것으로 나타났다.

• 한국지반공학회논문집
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• 제16권4호
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• pp.157-170
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• 2000

본 연구에서는 자연점토에 대한 구리 흡착 및 구리와 아연의 경쟁 흡착 시 온도변화에 따른 흙의 각 구성성분별 흡착거동을 살펴보기 위해 혼합 흡착-연속추출법(combined adsorption-sequential extraction analysis, CASA)을 사용하였다. 실험결과 중금속 아연의 경우 농도에 따른 차이는 있지만 온도증가에 따라 주로 이온교환 형태로 흡착되는 것을 알 수 있고, 구리와 경쟁흡착의 경우 이러한 경향은 더욱 커져서 약 80~90%정도가 이온교환형태로 흡착되어진다. 반면 구리의 경우 실험을 수행한 거의 모든 농도 범위에서 약 50%이상이 탄산염 형태로 흡착되어진다. 탄산염형태로의 흡착 양상은 단일 흡착의 경우 온도증가에 따라 약 5% 증가하는 경향을 보이고, 경쟁흡착의 경우에는 약 10%정도 증가하는 경향을 나타내었다. 그리고 자연점토에서의 아연과 구리의 각 구성성분 별 흡착거동은 이온 교환 형태로 분배되는 경우를 제외하고는 온도증가에 따라 흡착량이 증가하는 흡열반응$(\DeltaH0>0)$인 것으로 나타났다.

• 한국분말재료학회지
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• 제30권1호
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• pp.53-64
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• 2023

Atomic layer etching (ALE) is a promising technique with atomic-level thickness controllability and high selectivity based on self-limiting surface reactions. ALE is performed by sequential exposure of the film surface to reactants, which results in surface modification and release of volatile species. Among the various ALE methods, thermal ALE involves a thermally activated reaction by employing gas species to release the modified surface without using energetic species, such as accelerated ions and neutral beams. In this study, the basic principle and surface reaction mechanisms of thermal ALE?processes, including "fluorination-ligand exchange reaction", "conversion-etch reaction", "conversion-fluorination reaction", "oxidation-fluorination reaction", "oxidation-ligand exchange reaction", and "oxidation-conversion-fluorination reaction" are described. In addition, the reported thermal ALE processes for the removal of various oxides, metals, and nitrides are presented.

• 한국분말재료학회지
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• 제23권3호
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• pp.221-227
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• 2016

Waste oyster shells create several serious problems; however, only some parts of them are being utilized currently. The ideal solution would be to convert the waste shells into a product that is both environmentally beneficial and economically viable. An experimental study is carried out to investigate the recycling possibilities for oyster shell waste. Bulk ceramic bodies are produced from the oyster shell powder in three sequential processes. First, the shell powder is calcined to form calcium oxide CaO, which is then slaked by a slaking reaction with water to produce calcium hydroxide $Ca(OH)_2$. Then, calcium hydroxide powder is formed by uniaxial pressing. Finally, the calcium hydroxide compact is reconverted to calcium carbonate via a carbonation reaction with carbon dioxide released from the shell powder bed during firing at $550^{\circ}C$. The bulk body obtained from waste oyster shells could be utilized as a marine structural porous material.