• Journal of the Korean Chemical Society
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• v.53 no.4
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• pp.427-431
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• 2009

The thermodynamical mechanism of the extraction of soybean isoflavones from soybean residuals using organic solvent method has been studied. On the basis of experiments, a simple model for determining the distribution coefficients in organic solvent extraction was employed to calculate the thermodynamical functions between $K,\;{\Delta}H^0,\;{\Delta}S^0\;and\;{\Delta}G^0$ in the soybean isoflavones extraction process. The results show that the soybean isoflavones extraction is an endothermic and an entropy-increasing process: the ${\Delta}G^0$ decreases when the temperature arises.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.360-367
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• 1993

텅스텐 박막 증착의 메카니즘을 밝히기 위하여 먼저 SiH4와 WF6의 열분해 반응에 관한 열역학적 결과들과 표면 촉매 반응에 대한 이론적인 결과들을 고찰하였다. 실험적으론 저압 화학기상 증착법을 이용하여 WF6를 SiH4로 환원시켜 텅스텐 박막을 Si(100) 기판위에 증착하였으며 증착반응 중의 기판 표면의 변화를 in-situ로 측정하였다. 증착 메카니즘을 밝히기 위하여 반응기체를 WF6, SiH4, WF6＋SiH4, WF6$\longrightarrow$SiH4$\longrightarrow$WF6＋SiH4로 달리하여 반응시켰으며 그 때의 박막 특성과 표면 및 단면 형상을 측정하였다. 이론적인 고찰과 실험적인 결과들로부터 텅스텐 박막은 먼저 Si 기판에 의한 WF6의 환원반응으로 인한 증착과 이어서 SiH4에 의한 WF6의 환원으로 증착됨을 밝혔다.

• Journal of the Korean Chemical Society
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• v.41 no.4
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• pp.198-204
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• 1997

The rate constants for the hydrolysis of N-(2,4-dinitrophenyl)benzhydrazonyl bromide and its derivatives were determined by ultraviolet visible spectrophotometry at 20$^{\circ}C$ and a rate equation which could be applied over a wide pH range was obtained. On the basis of rate equations derived and judging from the solvent effect, substituent effect, salt effect, thermodynamic parameter, plausible mechanisms of hydrolysis have been proposed. It may be concluded that the hydrolysis through SN1 mechanism via carbonium ion intermdiate to pH 3.0, and pH 10.0, the hydrolysis proceeds through 1,3-dipolar or SN2 mechanism.

• Journal of the Korean Chemical Society
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• v.28 no.4
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• pp.265-268
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• 1984

Rates of reactions of nine m-or p-substituted phenacyl bromides with quinoline in methanol were measured by an electric conductivity method. These reactions were found to proceed through an $S_N2$ path and were accelerated by both electron-donating and electron-withdrawing substituents. A plausible reaction mechanism for this observation was proposed. Some activation parameters for these reactions were also calculated.

• Tribology and Lubricants
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• v.4 no.1
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• pp.36-42
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• 1988

On the basis of the thermally-activated Wear theory, it is well estabilished that the secondary activated energy, which is mainly resulted from the exothermic reaction of hydrogen from thermal decomposition of the hydrocarbons at the high temperature and the high speed, caused catastropic failure. The new additive, viz., DEP was synthesized to reduce or eliminate the hydrogen effect at the contact junction. Through the thermal degrading and the thermodynamic consideration, the synthesized additive, viz., DEP showed the possibiliy as the hydrogen scavenger.

• Polymer Science and Technology
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• v.24 no.6
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• pp.585-589
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• 2013

고분자 시스템에서 동역학은 열역학적 평형상태에 도달하는 메카니즘을 밝히는 중요한 분야이다. 용융 고분자에 비해 상대적으로 블록 공중합체 마이셀에 대한 동역학 연구는 실험적 한계와 이론적 배경의 부재로 인해 충분한 연구가 이루어지지 못하였다. 하지만, 최근 TR-SANS를 이용하여 고분자 마이셀의 동역학 연구가 점차 증가하고 있는 추세이다. 마이셀 동역학과 관련하여 현재까지 이루어진 연구 결과도 충분히 중요한 통찰력을 제시해주고 있지만, 아직 개척되지 못한 부분이 많이 남아있는 것도 사실이다. TR-SANS의 개념은 고분자 마이셀 뿐만 아니라 다양한 고분자 시스템에 적용할 수 있고, 더 나아가 Neutron Reflectivity에 적용할 경우 박막 내에서 고분자의 동역학도 연구할 수 있을 것으로 기대된다. 또한, TR-SANS 개념은 고분자 동역학 연구 분야 외에도 의학/생명공학 등 넓은 분야에서 이용될 수 있을 것으로 기대된다.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.164-167
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• 1989

The rate for the aquation of $trans-[Cr(tmd)_2FX]^+(X=F^-,\;Cl^-)$ ion in aqueous acidic solution has been measured by spectrophotometric method at various temperatures and pressures. The rate constants are increased with increasing temperatures and pressures. The values of activation entropy are 5.2 eu for $trans-[Cr(tmd)_2F_2]^+$ and -16.62 eu for $trans-[Cr(tmd)_2FCl]^+$ ions. Activation volumes have all negative values and lie in the limited range $-3∼-2\;cm^3mol^{-1}$ for $trans-[Cr(tmd)_2F_2]^+$ and $-8∼-7\;cm^3mol^{-1} for $trans-[Cr(tmd)_2FCl]^+$ ion. From the above results, we may deduce that the mechanism for the aquation of $trans-[Cr(tmd)_2F_2]^+$ and $trans-[Cr(tmd)_2FCl]^+$ ions is interchange-associative mechanism and dissociative mechanism respectively.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.472-477
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• 1985

The rates for the aquation of $cis-[Co(en)(NH_3)_2Cl_2]Cl in acetone-water mixtures have been measured at various pressures and temperatures by the electric conductivity method. The rate constant measured at 25$^{\circ}$C in pure water solvent is 3.47 ${\times}10^{-4}$/sec. Rate constants are increased with increasing temperature, and decreased with increasing pressure and mole fraction of acetone. Activation volumes and other activation parameters are calculated from these rate constants. The activation volumes are all positive and lie in the limited range +2.82~+$8.2cm^3$/mole. The rate constants in aqueous acetone solution are analyzed with the solvent compositions. Plots of log $k_{obs}$ vs. Grunwald-Winstein Y values show that log $k_{obs}$ varies linearly and the gradients are about 0.25. The applications of a free energy cycle relating the process initial state ${\to}$ transition state in water to that in acetone-water mixture show that the changes in solvation of the transition state have a dominant effect on the rate. From these results the aquation of this complex would be discussed in terms of dissociative mechanism ($I_d$).

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.483-489
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• 1990

The rate of hydrolysis of insecticidal 2-chloro-l-(2,4,5-trichlorophenyl)-vinyldimethylphosphate(Gardona) have been investigated in 25${\%}$ aqueous methanol. Studies at varying pH suggest that the hydrolysis of Gardona proceeds through the bimolecular (Ad$_{N-E}$) mechanism involving the transition state and carbanion intermediate as evidenced by solvent effect (m < 0.4, n < 0.7, [m] ${\ll}$ [l](associative SN$_2$ type)), thermodynamic parameters (${\{Delta}S^{\neq}$ = -27∼-32 e.u. & ${\{Delta}H^{\neq}$ = 13∼18 Kcal/mole), hydrolysis rate equation (k = k$_A+_B$ [OH-]), general base catalysis and hydrolysis product analysis, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.97-105
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• 1998

Antioxidation mechanism of Al metal powders on $Al_2O_3-C$ refractory was investigated in temperature range from 800 to $1400^{\circ}C$. The addition of 5 wt% Al metal powders suppressed the oxidation of carbon in $Al_2O_3$-C sample. The carbons were distributed uniformly on the surface and the interface of the $Al_2O_3$-C-Al. Reaction products of $Al_4C_3$ and AIN were found with a composition of Al-C at temperatures between 800 and $1200^{\circ}C$ and transformed to $Al_2O_3$ above $1400^{\circ}C$. Cavity structures related to the to the formation of $Al_4C_3$ were observed for the AI-C after heating at $1000^{\circ}C$ ofr 1 hour. Thermodynamic mechanism was considered to discuss the formation $Al_4C_3$, AlN and their transformation to $Al_2O_3$, which leads to the effect of oxidation resistance.