• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.358-363
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• 1976

Kinetic studies on solvolytic reactions of 1-and 2-naphthalene sulfonyl chlorides in ethanol-water mixtures have been carried out by means of conductometry at several temperatures. The rate constant for 2-naphthyl compound was larger than that for 1-naphthyl compound. This was contrary to the prediction of MO theory and could be rationalized as due to the peri-hydrogen effect in the transition state for 1-naphthyl compound. Based on m values of Winstein plots and n values of Kivinen pacolots it was concluded that the solvolytic displacement of the two naphthalene sulfonyl chlorides in ethanol-water mixtures proceed via $S_N2$ process.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.23-31
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• 2016

자유 라디칼을 이용한 RAFT 중합은 성장하는 고분자 반응을 제어할 수 있는 특성이 있어 주목 받고 있는 고분자 합성방법 중 하나이다. 이 반응의 기작은 agent라 불리는 분자를 주축으로 삼아 단량체들을 단계적으로 성장하는 가역적 방법으로 원하지 않는 종결반응으로부터 고분자 라디칼을 보호하는 역할을 수행한다. 보호의 근본적인 원인은 중간체 상태에서의 안정화 정도와 관련이 있으나 안정해진 만큼 반응속도가 느려지는 지연효과가 발생한다. 지연효과를 유도하는 원인은 많은 논란이 있었으며 그 중 하나로 agent에 존재하는 Z 치환기의 영향을 원인으로 지목하고 있다. 본 연구는 Z 치환기의 변화에 따른 안정화 정도를 파악하기 위하여 RAFT agent로 주로 이용하는 것 중 두 개의 황이 있는 dithioester와 xanthate를 WxMacMolplt 7.3.2를 이용하여 propagation 초기 단계를 구현한 후 GAMESS2 프로그램을 이용하여 양자화학적 계산을 수행하였다. 계산결과 안정화 에너지와 경계 궤도함수에서는 phenyl기가 있을 때 공명효과에 의하여 안정화가 이루어졌으며 또한 propyl benzyl에서도 늘어난 알킬 사슬의 donating effect로 인한 안정화 영향의 범위를 발견하였다. PES 기법을 통해 두 methyl 단량체를 움직이면서 반응하는 동안의 에너지 변화를 알아보았으며 그 결과 dithioester는 Z 치환기의 변화에 더 많이 의존한다는 것을 확인하였다. 본 연구를 종합해본 결과 phenyl을 제외한 aryl기가 있는 dithioester는 낮은 addition 퍼텐셜과 안정화 에너지를 가질 수 있을 것이고 지연효과를 줄일 수 있을 것으로 기대된다.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.235-244
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• 2011

A batch experiment of pyrite oxidation was performed and the surfaces of the reacted pyrite were regularly observed with the scanning electron microscope (SEM) together with the chemical compositions of the solution to help understand the oxidation mechanisms of pyrite by Acidithiobacillus ferrooxidans (Af). The dissolved Fe concentrations clearly indicated that Af experiences the lag and then exponential growth phase. An Af cell was observed to be attached to the surface of pyrite during the lag, implying that a direct leaching by the microbe really happens for the period. It is not certain, however, whether the main mechanism of pyrite oxidation during that time was the direct leaching or not, because there were just a few cells confirmed to be attached and most of the dissolved Fe was Fe(III). The dissolved Fe concentration stayed almost constant from the mid-lag phase to just before the onset of the exponential phase, suggesting that AI needs an adaptation time to switch its oxidation mechanism from one to the other whichever it is during that stage of growth. The moment of Af's cell division was observed by SEM on the surface of pyrite during the lag phase. The corrosion outline around the dividing cell was quite similar to the shape of the cell itself, which implies that the rate of the microbial oxidation is very uneven and the rate when the cell metabolizes should be much faster than that calculated from the concentration variation of the dissolved Fe. The number of etch holes by Af is much higher on the inoculated surfaces, indicating the average rate of pyrite oxidation is also much faster than that of abiotic oxidation. The microbial etch holes on pyrite surface are small and deep, which may influence the transition of the growth phases of Af from lag to exponential.

• Composites Research
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• v.22 no.3
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• pp.35-43
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• 2009

In this study, for a radiator hose made of carbon black filled EPDM(ethylene-propylene diene monomer) rubber, a measuring method of crosslink density was established to analyze the aging behaviors under thermo-oxidative stresses. At $125^{\circ}C$, the crosslink density of the rubber specimens decreased slightly in the initial stage, but increased with increasing the aging time. Such variation in crosslink density was similar to that of tensile strength. This might be due to the formation of sulphoxide crosslinks as well as to additional crosslinks made by the reaction of unvalcunized sulfurs. A high temperature aging of rubber specimens at $180^{\circ}C$ caused a slight increase in crosslink density while it did a large decrease in tensile strength and elongation. With aging at high temperature, the formation of carbonyl groups in EPDM molecule chain and formation of sulphoxide crosslink, rather than the crosslink density variation itself, had a large influence on such changes in mechanical property.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1029-1034
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• 1998

Chick antibodies (IgY) raised against Streptococcus mutans (serotype c) were separated from egg yolk and their properties were investigated. The purity of IgY extracts prepared by the method of ${\lambda}-carrageenan$, $gammaYolk^{TM}$, and $EGGstract^{TM}$ was 20%, 46%, and 48%, respectively, and the yields of IgY extracts from a gram yolk were 11. 3 mg, 1.7 mg, and 1.8mg, respectively. Quantitative immunoprecipitation test showed that specific IgY content of crude IgY prepared by ${\lambda}-carrageenan$ method was 12.2%, which means that 0.85 g of crude IgY from an egg yolk (15 g) contains about 100 mg of specific IgY. When the reactivity of the specific IgY towards 3 caries-inducing strains (serotype: b, c, f) was examined, the strains cultured in sucrose-added medium showed higher reactivity (the orders were c(+), f(+), b(+)) than those cultured in sucrose-free medium. Heat and pH stability of specific IgY was good, for crude IgY contained 50% of antibody activity after heat treatment at $70^{\circ}C$ for 5 min and they were stable at pH $4{\sim}8$.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.91-92
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• 2019

이 논문은 에너지인터넷의 실시간 가격 수요 반응 시스템에서 금전적 이익 극대화를 위해 두 명의 플레이어가 있는 Stackelberg 게임 기반 진화 게임을 연구한다. 우리는 두 명의 플레이어인 발전자와 에너지 사용자의 통일된 이익을 극대화하는 대신 발전자와 에너지 사용자의 이익을 극대화하는 에너지 전략을 적용한다. 실시간 가격 수요 반응 시스템에서 적용한 에너지 전략을 시뮬레이션하였고 시뮬레이션 결과, 적용된 에너지 전략이 기존의 방식에 비해 발전자의 수익을 45 %까지 효과적으로 개선하고 에너지 사용자의 전기 요금을 평균 15.6 % 줄일 수 있음을 보여준다. 또한, 제안한 에너지 전략이 수요반응의 목표 중 하나인 피크 대 평균 비율 감소의 안정화에 기여할 수 있음을 확인했다.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.567-574
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• 1988

Kinetic studies on the vanadium(IV)-catalyzed oxidation of dimethylsulfoxide by hydrogen peroxide in water and aqueous methanol and ethanol show that the reaction is the first order in the concentration of dimethylsulfoxide and hydrogen peroxide, respectively. Activation parameters are also measured for the oxidation of dimethylsulfoxide. It is suggested that the rate determining step is a process involving oxidation of dimethylsulfoxide as the result of nucleophilic attack by the sulfur on the O-O bond of vanadium(V)-peroxide complex.

• Journal of the Korean Chemical Society
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• v.21 no.2
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• pp.83-88
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• 1977

Kinetic studies on the rates of reactions of 2, 4-dinitrochlorobenzene with p-toluidine, aniline and p-chloroaniline in $CH_3CH-CH_3OH$ binary solvent mixtures have been carried out. The experimental results have been explained in terms of the specific solvation by alcoholic hydrogen. It has been shown that the bond breaking step is rate determining in the solvent system studied and the energy barrier is getting low as the solvent changes from acetonitrile to methanol.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.11a
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• pp.295-301
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• 1999

본 연구에서는 특정 대상에 대한 사람들의 심리적인 색채반응을 측정할 수 있는 색채감성척도(PCS)를 개발하고 이것을 색채 감성 이미지의 평가에 어떻게 이용하는가를 보여주고자 한다. 색채심리에 기초한 색채감성척도(PCS)는 NCS와 ISCC-NBS 색명법에 의거한 색상과 톤의 개념으로 구성되었으며 기본형과 상세형의 두 가지가 개발 되었다. 표준화된 색채감성척도는 각 사람들마다 다르게 나타나는 색에 관한 이미지나 색에 대한 심리적인 선호반응을 객관적으로 측정할 수 있는 척도로 활용될 수 있다. 본 연구에서는 선호색, 선호의상색, 선호 화장품 색을 나타내는데 PCS가 어떻게 활용되는가를 보여주었다. PCS를 이용한 색채 감성 이미지는 Color Image Palette를 이용하여 각각의 특성을 비교할 수 있도록 제시되기도 하였다. 색채 경험에 대한 광학적이거나 물리적인 속성이 아닌 심리적인 특성을 평가하고 서로 다른 집단의 반응을 비교 평가하는데 PCS와 유용한 도구가 될 것이다.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.24-31
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• 2008

Sulfate reducing bacteria (SRB) is universally distributed in the sediment, especially in marine environment. SRB reduce sulfate as electron acceptor to hydrogen sulfide in anaerobic condition. Hydrogen sulfide is reducing agent enhancing the reduction of the organic and inorganic compounds. With SRB, therefore, the degradability of organic contaminants is expected to be enhanced. Ferrous iron reduced from the ferric iron which is mainly present in sediment also renders chlorinated organic compounds to be reduced state. The objectives of this study are: 1) to investigate the reduction of TCE by hydrogen sulfide generated by tht growth of SRB, 2) to estimate the reduction of TCE by ferrous iron generated due to oxidation of hydrogen sulfide, and 3) to illuminate the interaction between SRB and ferrous iron. Mixed bacteria was cultivated from the sludge of the sewage treatment plant. Increasing hydrogen sulfide and decreasing sulfate confirmed the existence of SRB in mixed culture. Although hydrogen sulfide lonely could reduce TCE, the concentration of hydrogen sulfide produced by SRB was not sufficient to reduce TCE directly. With hematite as ferric iron, hydrogen sulfide produced by SRB was consumed to reduce ferric ion to ferrous ion and ferrous iron produced by hydrogen sulfide oxidation decreased the concentration of TCE. Tests with seawater confirmed that the activity of SRB was dependent on the carbon source concentration.