• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
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• pp.45-48
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• 1998

For the single crystal growth of silicon, a global analysis of heat transfer in a CZ furnace was carried out using the finite element method, where the radiative heat transfer between the surfaces that possess both specular and/or diffuse reflectance components was taken into account, and then the effect of the specular reflection of the crystal and/or melt on the CZ crystal growth was numerically investigated.

• 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.

• 한국세라믹학회지
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• 제45권12호
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• pp.845-850
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• 2008

Hydrated sodium silicate was synthesized by hydrothermal reaction using anhydrous sodium silicate. The optimum additions of water was 25wt% to make hydrated sodium silicate with homogeneous and purposed water contents. Porous ceramics with homogeneous microstructure and spherical closed pore can be fabricated by elimination of the large pores(a few mm in size) which was formed during first heat treatment through the decomposition of water. Spherical closed pore was formed above $600^{\circ}C$ and the pore size was increased with increasing second heat treatment temperature due to growth of pores. The size of spherical closed pore was varied from 35 to $233\;{\mu}m$ and specific gravity was varied from 0.2 to 1.02 depending on the combinations of the first and second heat treatment temperature.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.37-40
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• 2012

In an entrained flow coal gasifier, predicting the reaction behavior of pulverized coal particles requires detailed information on devolatilization, char gasification, gaseous reactions, turbulence and heat transfer. Among the input parameters, the rate of devolatilization and the composition of volatile species are difficult to determine by experiments due to a high pressure (~40 bar) and temperature (${\sim}1500^{\circ}C$). This study investigates the effect of devolatilization models on the reaction and heat transfer characteristics of a 300 MWe Shell coal gasifier. A simplified devolatilization model and advanced model based on Flashchain were evaluated, which had different volatiles composition and devolatilization rates. It was found that the tested models produce similar flow and reaction trends, but the simplified model slightly over-predict the temperature and wall heat flux near the coal inlets.

• 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.

• Journal of Ginseng Research
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• 제7권1호
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• pp.88-93
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• 1983

Studies were carried out to elucidate the protein stabilizing effect of ginseng. Malate dehydrogenase (EC 1.1.1.37) was used as a protein and the rate constant of the enzyme inactivation was determined under the heat denaturation condition. There was an optimum pH for the enzyme stability, the rate constant of the enzyme inactivation was minimum at BH 8.8. The rate constant was increased at lower and higher pH regions than the optimum pH. The inactivation reaction followed the Arrehnius law and the activation energy was measured as 36.8kcal/mole. The reaction rate was not affected by the enzyme concentration and thus it was assumed to be unimolecular first order reaction. The water extract of red ginseng decreased the rate constant of Malate dehydrogenate under heat inactivation condition to stabilize the enzyme activity. Purified ginseng saponin also stabilized the enzyme against heat inactivation.

• Environmental Engineering Research
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• 제10권3호
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• pp.122-130
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• 2005

Gasification of carbonaceous wastes such as shredded tire, waste lubricating oil, plastics, and powdered coal initiates a single-stage reforming reactor(reformer) Without catalyst and a syngas burner. Syngas is combusted with $O_2$ gas in the syngas burner to produce $H_2O\;{and}\;CO_2$ gas with exothermic heat. Reaction products are introduced into the reforming reactor, reaction heat from syngas burner elevates the temperature of reactor above $1,200^{\circ}C$, and hydrogen gas fraction reaches 65% of the product gas output. Reactants and heat necessary for the reaction are provided through the syngas burner only. Neither $O_2$ gas nor steam is injected into the reforming reactor. Multiple syngas burners may be connected to the reforming reactor in order to increase the syngas output, and the product syngas is recycled into syngas burner.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2262-2275
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• 2022

The Korea Atomic Energy Research Institute (KAERI) studied the sodium-water reaction (SWR) minimized steam generator for the safety of the sodium-cooled fast reactor (SFR), and selected the copper bonded steam generator (CBSG) as the optimal concept. This paper introduces the conceptual design of the CBSG and the development of the CBSG sizing analyzer (CBSGSA). The CBSG consists of multiple heat transfer modules with a crossflow heat transfer configuration where sodium flows horizontally and water flows vertically. The heat transfer modules are stacked along a vertical direction to achieve the targeted large heat transfer capacity. The CBSGSA code was developed for the thermal-hydraulic analysis of the CBSG in a multi-pass crossflow heat transfer configuration. Finally, we conducted a preliminary sizing and rating analysis of the CBSG for the trans-uranium (TRU) core system using the CBSGSA code proposed by KAERI.

• 한국수소및신에너지학회논문집
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• 제32권3호
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• pp.180-188
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• 2021

This paper conducted a study on the ortho-para hydrogen conversion in the cryogenic heat exchanger filled with catalysts for hydrogen liquefaction by utilizing the numerical model of plate-fin heat exchanger considering catalytic reaction of ortho-para hydrogen conversion, heat and mass transfer phenomena and fluid dynamics in a porous medium. Various numerical analyzes were performed to investigate the characteristics of ortho-para hydrogen conversion, the effects of space velocity and activated catalyst performance.

• 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.