• 한국응용과학기술학회지
• /
• 제12권2호
• /
• pp.85-92
• /
• 1995

The rate constant of the nucleophilic addition of 1-propanethiol to ${\alpha}-phenyl-N-iso-propylnitrone$ derivatives were determined at various pH and a rate equation which can be applied over wide pH range is obtained. Final product of the addition reaction was ${\alpha}-thiopropyl-p-phenylbenzylideneamine$. Base on the rate equation, general base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Below pH 3.0, the reaction was initiated by the addition of 1-propanthiol, and in the range of pH 3.0-10.0, proceeded by the competitive addition of 1-propanethiol and propanethiolate. Above the pH 10.0, the reaction proceeded through the addition of propanethiolate.

• 한국재료학회지
• /
• 제5권6호
• /
• pp.667-672
• /
• 1995

DGEBA (diglycidyl ether of bisphenol A )/MDA(4,4'-methylene dianiline)/SN(succinonitrile)계와 DGEBA/MDA/SN/HQ(hydroquinone)계의 경화반응 속도론을 Kissinger equation 및 Fractional life 법에 의해 85~15$0^{\circ}C$에서 DSC를 이용하여 연구하였다. 경화반응 온도가 높아짐에 따라 반응속도는 증가하는 반면, 반응차수는 거의 일정하였다. 또한 촉매로 HQ를 첨가한 계가 첨가하지 않은 계보다 반응속도는 크게 증가했으며, 활성화 에너지 값은 약 20% 정도 감소하였다 또한, 경화반응 시작온도는 3$0^{\circ}C$ 정도 낮아졌다.

• International Journal of Contents
• /
• 제6권2호
• /
• pp.6-9
• /
• 2010

Using symplectic relation and reaction concept, we propose a planar near-field antenna measurement method. A generalized probe compensation equation is deduced to obtain the probe correction formulation. To verify our approach, a reflector antenna with $1{\times}2$ horn array is fabricated and measured in the near-field measurement facility. The near-field measurement results are compared with the physical optics (PO) simulation. The results of measurement and simulation agree very well near to the mainbeam.

• 호남수학학술지
• /
• 제14권1호
• /
• pp.67-84
• /
• 1992

• Bulletin of the Korean Chemical Society
• /
• 제7권4호
• /
• pp.321-323
• /
• 1986

• 대한화학회지
• /
• 제18권6호
• /
• pp.423-429
• /
• 1974

$ {\alpha}$-Cyano-$ {\beta}$-piperonylacrylic acid(CPA)에 대한 hydorogen cyanide의 진핵성 첨가 반응속도 상수를 측정하여 넓은 pH범위에서 잘 맞는 반응 속도식을 구하였다. 이 식에 의하면 pH3이하에서는 CPA에 대해 hydrogen cyanide분자의 첨가 반응이 일어나지만 pH6에서 8사이는 hydrogen cyanide가 $ {\alpha}$-cyano-$ {\beta}$-piperonyl acrylate ion에 첨가함을 알수 있고, 또 pH 3과 6사이에서는 이들 두 반응이 경쟁적으로 일어난다. 그리고 pH9이상에서는 $ {\alpha}$-cyano-$ {\beta}$-piperonyl acrylate ion에 cyanide ion이 첨가하는 반응이 일어나며 pH3에서 9까지의 모든 복잡한 반응 메카니즘도 이식으로 충분히 설명할 수 있음을 알았다.

• Bulletin of the Korean Chemical Society
• /
• 제32권3호
• /
• pp.993-999
• /
• 2011

The photoreactive prepolymers with multifunctional cinnamate and bisphenol Atype cinnamate groups that could perform photodimerization without photoinitiators were synthesized by the reaction of t-cinnamic acids (CAs) and epoxy resins. Their photocure reaction rates and the extent of reaction conversion were measured with Fourier transform infrared spectroscopy, and these increased with the intensity of UVirradiation. The experimental data of these reaction rates showed the characteristics of nth-order kinetics reaction, and all kinetic constants of each photoreactive polymer with this equation were summarized. Although the GTR-1800-HCA and KWG1-EP-HCA with hydroxyl group substituted cinnamate showed lower reaction conversion rates and rate constant than GTR-1800-CA and KWG1-EP-CAwith an unsubstituted cinnamate group, GTR-1800-MCAand KWG1-EP-MCAwith methoxy group substituted cinnamate showed similar and higher reaction conversion rates than the former, respectively. These results were explained in terms of segmental mobility for photopolymerization by molecular interactions.

• Bulletin of the Korean Chemical Society
• /
• 제18권9호
• /
• pp.985-994
• /
• 1997

The reaction of gas-phase atomic hydrogen with hydrogen atoms chemisorbed on Fe(110) surface is studied by use of classical trajectory procedures. Flow of energy between the reaction zone and bulk solid phase has been treated in the generalized Langevin equation approach. A London-Eyring-Polanyi-Sato energy surface is used for the reaction zone interaction. Most reactive events are found to occur in strong single-impact collisions on a subpicosecond scale via the Eley-Rideal mechanism. The extent of reaction is large and a major fraction of the available energy goes into the vibrational excitation of H2, exhibiting a vibrational population inversion. Dissipation of reaction energy to the heat bath can be adequately described using a seven-atom chain with the chain end bound to the rest of solid. The extent of reaction is not sensitive to the variation of surface temperature in the range of Ts=0-300 K in the fixed gas temperature, but it shows a minimum near 1000 K over the Tg=300-2500 K.

• 한국환경과학회지
• /
• 제8권2호
• /
• pp.227-231
• /
• 1999

This study was conducted to investigate the removal characteristics of $PO_4^{3-}-P$ contained in livestock wastewater using waste concrete. With small particle size, increased dosage and temperature of water, $PO_4^{3-}-P$ was well removed by waste concrete.$PO_4^{3-}-P$ was removed by adsorption reaction in low pH of the primary phase, but the crystallization reaction predominated for increasing pH with passed time. As a result of adapting the adsorption isotherm equation, $PO_4^{3-}-P$ removal was more affected by the crystallization reaction than the adsorption reaction. In the SEM micrograph, there was no evident change on the waste concreter surface. Particle size was plate-phase before reaction but appeared a dense form to progress in the crystallization reaction.

• 한국자동차공학회논문집
• /
• 제10권1호
• /
• pp.76-83
• /
• 2002

Mathematically and chemically simplified reaction scheme for n(heptane that simulates autoignitions of the end gases in spark ignition engines has been developed and studied computationally. The five(equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius pre-exponential constants, A, and heats of reaction for stoichiometric nheptane/air has all been optimized. Comparisons between computed and experimental autoignition delay times have validated the present simplified reaction scheme. The influences of heat loss and concentration of chain carrier at the beginning of compression upon autoignition delay times have been computationally investigated.