• 대한화학회지
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• 제62권1호
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• pp.68-72
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• 2018

• 한국응용과학기술학회지
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• 제9권1호
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• pp.41-46
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• 1992

The transesterification of dimethylphthalate by 1,4-butanediol was kinetically investigated In the presence of various metal acetate catalysts at 180$^{\circ}C$. The quantity of dimethylphthalate reacted in the reaction flask was measured by gas chromatography. The transesterification was assumed to obey first-order kinetics with respect to dimethylphthalate and 1,4-butanediol, and a rate equation was derived. The linear relationship was shown between apparent rate constant and reciprocal absolute temperature, the activation energy has been calculated as 7.4kcal with lead acetate. The maximum reaction rate was appeared at the range of 1.5${\sim}$1.6 of electronegativity of metal ions.

• 자연과학논문집
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• 제15권1호
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• pp.47-56
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• 2005

The substituent dependence of geometric distortion through the two independent electronic substituent effects is analyzed for mono-substituted benzene derivatives of $C_{2v}$. Based on resonance structures, quantitative relationships expressing the resonance and field/inductive contribution terms in bond distortions are derived. The calculated field-effect parts of $C_{ipso}$_$C_{ortho}$ ring bonds increase and decrease compared to benzene for electropositive and electronegative substituents respectively. The nonbonded axial distance, $C_{ipso}$....$C_{para'}$ decreases for electronegative substituents and increases for electropositive substituents. As the electronegativity increases, the distance $C_{ortho}$....$C_{ortho'}$ increases. With the $\pi$-donors, $C_{meta}$....$C_{meta'}$ nonbonded distances are shorter compared to the ones of benzene, and for $\pi$-acceptors, the are longer. Our model based on valence bond approach predicts that the average bond length determined the area of ring, and the sum of the angles <$C_{ortho}$_$C_{ispo}$_$C_{ortho}$ and <$C_{meta}$_$C_{para}$_$C_{meta}$ determines the axial distance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.438-440
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• 1995

The impedance characteristics and plasma parameters were experimentally studied in a weakly magnetized planar type, inductively coupled plasma (ICP) system. Compared with non-magnetized for system higher power transfer efficiency, stable impedance matching, enhancement of plasma density and higher electron temperature can be obtained. Such improvements are mainly due to the excitation of deeply penetrating electromagnetic wave and reduction of radial loss of electrons. In particulary, $SF_6$ (sulfur hexafluride) plasma shows unstable impedance matching in non-magnetized ICP because electronegativity of $SF_6$ effects on plasma characteristics. But, magnetized inductively coupled $SF_6$ plasma shows enough impedance matching stability to be applicable to the polysilicon etching in semiconductor process.

• 한국응용과학기술학회지
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• 제7권1호
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• pp.71-76
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• 1990

Transesterification reactions (methyl methacrylate with monoethanolamine, methyl methacrylate with n-butyl alcohol, dimethylphthalate with ethylene glycol, dimethyl phthalate with monoethanolamine) were kinetically investigated in the presense of various metal acetate catalysts at $110^{\circ}C$. The amount of reactants was measured by gas and liquid chromatography, and the reaction rates also measured from the amount of reaction products and reactants upon each catalyst. The transesterification reactions were carried out under the first order conditions respect to the concentration of reactants, respectively. The overall reaction order was 2nd, Maximum reaction rates were appeared at the range of 1.4 to 1.6 in electronegativity of metal ions and maximum catalytic activities were obserbed at the range of 1.5 to 1,8 in instability constant of metal acetates.

• 한국응용과학기술학회지
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• 제2권2호
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• pp.25-30
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• 1985

The transesterification reaction between diethanolamine and dimethylphthalate was kinetically investigated in the presence of various metal acetate catalysts at $130^{\circ}C$. The reaction was followed by the measurement of distilled methanol from the reaction vessel. The transesterification was found to obey first-order kinetics with respect to the concentration of diethanolamine and dimethylphthalate and catalyst, respectively. The reactivities has highest value where the electronegativity and instability constand (Kij) values for the metal acetate catalysts are about 1.6.

• 한국응용과학기술학회지
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• 제2권2호
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• pp.31-38
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• 1985

The transesterification reaction between ethanolamine and methyl-methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $110^{\circ}C$. The transesterification was found to obey first-order kinetice with respect to the concentration of ethanolamine and methyl-methacrylate, respectively. By the Arrhenius plot, the activation energy has been calculated as 11.9 Kcal with lead acetate catalyst, 14.7 Kcal without catalyst. The reactivities has highest value where the electronegativity and instability constant (Kij) values for the metal acetate catalysts are about 1.6.

• 반도체디스플레이기술학회지
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• 제13권1호
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• pp.63-66
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• 2014

ZnO is a wide bandgap (3.3 eV) semiconductor with high mobility and good optical transparency. However, off-current characteristics of ZnO thin-film transistor (TFT) need improvements. In this work we studied the variation in ZnO TFT current under different annealing conditions. Annealing usually modifies gas adsorption at grain boundaries of ZnO. When oxygen is adsorbed, electron density decreases due to strong electronegativity of the oxygen, and TFT current decreases as a result. Our experiments showed that current increased after vacuum annealing and decreased after air annealing. We explain that the change of off-current is caused by the desorption and adsorption of oxygen at the grain boundaries.

• 한국응용과학기술학회지
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• 제4권1호
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• pp.67-71
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• 1987

The transesterification reaction between diethanolamine and methyl methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $120^{\circ}C$. The amount of reacted methyl methacrylate was measured by gas chromatography and liquid chromatography, and the reaction rate also measured from the amount of reaction products and reactants under each catalyst. The transesterification reaction was carried out in the first order with respect to the concentration of diethanolamine and methyl methacrylate, respectively. The over-all order is 2nd. The apparent rate constant was found to obey first-order kinetics with respect to the concentration of catalyst. The maximum reaction rate was appeared at the range of 1.4 to 1.6 of electronegativity of metal ions and instability constant of metal acetates.

• Bulletin of the Korean Chemical Society
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• 제17권9호
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• pp.849-853
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• 1996

Hetero Dieis-Alder reactions containing phosphorus atom at various positions of diene and dienophile as well as standard Dieis-Alder reaction between ethylene and cis-l,3-butadiene have been studied using ab initio method. Activation energy showed a good linear relationship with the FMO energy gap between diene and dienophile, which can be normally used to explain Dieis-Alder reactivity. Since π-bond cleavage and σ-bonds formation occur concertedly at the TS, geometrical distortion of diene and dienophile from the reactant to the transition state is the source of barrier. Based on the linear correlations between activation barrier and deformation energy, and between deformation energy and π-bond order change, it was concluded that the activation barrier arises mainly from the breakage of π-bonds in diene and dienophile. Stabilization due to favorable orbital interaction is relatively small. The geometrical distortions raise MO levels of the TS, which is the origin of the activation energy. The lower barrier for the reactions of phosphorus containing dienophile (reactions C, D, and E) can be explained by the electronegativity effect of the phosphorus atom.