• The Korean Journal of Ceramics
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• 제1권1호
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• pp.40-44
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• 1995

Ethylammonium-layered aluminosilicates intercalates were prepared by ion exchange reaction between the layered silicates with different layer changes density of 0.32∼0.41 e per unit formula and ethylammonium chloride. A kinetic study on the thermal deintercalation of the ethylammonium-layered silicate intercalates was carried out by range of 350℃ to 480℃ (heating rate of 10℃/min). Based on the Ozawa's method, the activation energies of the thermal deintercalation reaction were estimated as 171.2∼133.0 kJ/mol, which increase linearly with the layer charge densities.

• 한국안전학회지
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• 제12권3호
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• pp.106-113
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• 1997

The thermal characteristics of two binary mixtures by sodium azide/manganese dioxide and ferric oxide, two ternary mixtures by sodium azide/silicon dioxide/manganese dioxide and ferric oxide were studied to obtain the basic data of gas-generating agents for air bags. The thermal reaction for all mixtures started at about $420^{\circ}C$, but the temperature at which the reaction rate reached a maximum was different with the states of samples. According to reaction results, nitrogen, nitrogen oxide and nitrogen dioxide were detected by GC-MS and so many kinds of new chemicals from sodium azide and metal oxide mixtures by XRD. NMS is considered as most stable and reasonable mixture for this types of gas-generating agents.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제21권1호
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• pp.39-61
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• 2017

In this present article, we analyzed the heat and mass transfer characteristics of the nonlinear unsteady radiative MHD flow of a viscous, incompressible and electrically conducting fluid past an infinite vertical porous plate under the influence of Soret and chemical reaction effects. The effect of physical parameters are accounted for two distinct types of thermal boundary conditions namely prescribed uniform wall temperature thermal boundary condition and prescribed heat flux thermal boundary condition. Based on the flow nature, the dimensionless flow governing equations are resolved to harmonic and non harmonic parts. In particular skin friction coefficient, Nusselt number and Sherwood number are found to evolve into their steady state case in the large time limit. Parametric study of the solutions are conducted and discussed.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1636-1644
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• 2017

The main purpose of this article is to describe the magnetohydrodynamic stagnation point flow of Walter-B nanofluid over a stretching sheet. The phenomena of heat and mass transfer are based on the involvement of thermal radiation and chemical reaction. Characteristics of Newtonian heating are given special attention. The Brownian motion and thermophoresis models are introduced in the temperature and concentration expressions. Appropriate variables are implemented for the transformation of partial differential frameworks into sets of ordinary differential equations. Plots for velocity, temperature, and nanoparticle concentration are displayed and analyzed for governing parameters. The skin friction coefficient and local Nusselt and Sherwood numbers are studied using numerical values. The temperature and heat transfer rate are enhanced within the frame of the thermal conjugate parameter.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.75-76
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• 2018

MiDF, Micro Defect Free concrete, is the concrete made for high strength development by minimizing the defects such as micro pore and ITZ. Since MiDF exhibits strength through hydro-thermal synthesis reaction, it is essential to select the optimum C/S mole ratio. In this study, the basic characteristics of MiDF were evaluated by controlling the C/S mole ratio by SF and QP.

• Advances in environmental research
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• 제1권3호
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• pp.191-199
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• 2012

A kinetic study of the transesterification of soybean oil was conducted using microwaves under various temperatures, power densities, and reaction times. Results show that power density affects the kinetics and yield. The biodiesel yield increased with increasing microwave power density. The non-thermal effects of microwave irradiation on transesterification reactions were evaluated at a constant reaction temperature ($65^{\circ}C$) and power density (0.204 $Wg^{-1}$). Microwave irradiation was found to increase the reaction rates by 3.52-7.06 fold.

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.999-1004
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• 2001

(1-Chloro-2,2-dicyanovinyl)benzene or 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene was reacted with 2-amino-phenol to give the model compound, hydroxy enaminonitrile, which was found to undergo thermal cyclization reaction to form the corresponding benzoxazole. This intramolecular cyclization reaction is expected to occur through nucleophilic attack to electropositive enamine carbon by ortho-hydroxy group on the phenyl ring, which is accompanied by the release of neutral malononitrile through rearrangement. From each bifunctional monomer, o-hydroxy substituted polyenaminonitrile was prepared and characterized as a new precursor polymer for well-known aromatic polybenzoxazole. Also the unusual macrocyclic dimer formation from the 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane polymerization reaction system was discussed. The thermal cyclization reactions and the properties of polymers were investigated using FT-IR and thermal analysis (DSC & TGA).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.174-175
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• 2022

The blast furnace slag, which is widely used as a cement admixture, has latent hydraulics under the influence of cement hydrate, and fly ash and silica fume mainly cause a pozolane reaction. As a result, the cement structure becomes dense, and it is possible to compensate for defects when concrete is usually made with portland cement alone. When fixing carbon dioxide through reaction with carbon dioxide, the amount of calcium hydroxide in the cement paste is important. The larger the amount of calcium hydroxide, the more active the reaction may occur. It is also an important variable in calculating the depth of neutralization through carbonization. In this study, calcium hydroxide in cement paste using mixed materials was quantified through thermal analysis.

• 약학회지
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• 제25권3호
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• pp.83-87
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• 1981

Reaction of 3-chloroindolenine with acetic acid gives oxindole and acetoxyindole. Similar treatment of 3-bromoindolenine affords 6-bromoindole. Reaction of 3-chloro-and 3-bromoindolenine with methanolic sodium hydroxide gives 3-methoxyindolenine, 2-methoxyindolenine and oxindole. Thermal reaction of 3-bromoindolenine in 1, 1', 2, 2'-tetrachloroethane gives 6-bromoindole but no reaction is occurred in 3-chloroindolenine. Photolysis of 3-chloroindolenine gives indole, 4-, 5- and 7-chloroindole.

• 공업화학
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• 제10권6호
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• pp.885-888
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• 1999

본 연구에서는 $Na_2B_4O_7{\cdot}10H_2O/Na_2B_4O_7{\cdot}5H_2O$ 반응계의 열분해 탈수반응에 의한 반응속도상수를 결정하고 반응계의 재현성 및 화학축열재의 반복사용에 따른 내구성을 검토하였다. 반응계의 열분해 탈수반응의 차수는 1차이었고, 열분해 탈수 반응속도는 수증기의 분압차에 정비례하였다. 반응계의 반응속도상수는 약 0.27이었고, 반응속도상수와 반응차수에 대한 반응의 재현성이 우수하였다. 또한 화학축열재의 내구성은 연속적으로 반복 사용하여도 활성변화는 ${\pm}5%$ 범위 내에 있었다.