• Title, Summary, Keyword: model reaction

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A discussion on the application of particle reaction model for iron ore pellet induration process modeling (탄재를 포함한 산화철 펠릿 소성 공정 수치 모델의 입자 반응 모델 적용)

  • Ahn, Hyungjun;Choi, Sangmin
    • 한국연소학회:학술대회논문집
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    • pp.165-166
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    • 2014
  • The application of particle reaction model in the packed bed process modeling is discussed for iron ore pellet induration process. Combustion of coke breeze in the pellet is estimated by using shrinking unreacted-core model and grain model in which the progress of chemical reaction is described in different concepts. Under the identical inlet gas and solid conditions, the calculation using shrinking core model showed deviated results in terms of temperature profile and conversion fraction, which may imply the significance of selecting proper particle reaction model in consideration of particle characteristics and process operation conditions.

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Modeling of diffusion-reaction behavior of sulfate ion in concrete under sulfate environments

  • Zuo, Xiao-Bao;Sun, Wei;Li, Hua;Zhao, Yu-Kui
    • Computers and Concrete
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    • v.10 no.1
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    • pp.79-93
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    • 2012
  • This paper estimates theoretically the diffusion-reaction behaviour of sulfate ion in concrete caused by environmental sulfate attack. Based on Fick's second law and chemical reaction kinetics, a nonlinear and nonsteady diffusion-reaction equation of sulfate ion in concrete, in which the variable diffusion coefficient and the chemical reactions depleting sulfate ion concentration in concrete are considered, is proposed. The finite difference method is utilized to solve the diffusion-reaction equation of sulfate ion in concrete, and then it is used to simulate the diffusion-reaction process and the concentration distribution of sulfate ion in concrete. Afterwards, the experiments for measuring the sulfate ion concentration in concrete are carried out by using EDTA method to verify the proposal model, and results show that the proposed model is basically in agreement with the experimental results. Finally, Numerical example has been completed to investigate the diffusion-reaction behavior of sulfate ion in the concrete plate specimen immersed into sulfate solution.

Model System Study for the Mutagenicity of Sugar-Glycine Systems

  • Lee, Jae-Hwan;Shin, Han-Seung
    • Food Science and Biotechnology
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    • v.17 no.4
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    • pp.839-841
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    • 2008
  • The mutagenicity after heating of different sugars (glucose, fructose, galactose, and tagatose) on the non-enzymatic browning reaction in different sugars and glycine model system was investigated. The model system containing 0.2 M glycine and 0.2 M of different sugars in 10 mL water was heated at $150{\pm}5^{\circ}C$ for 30 min. After heating, degree of non-browning reaction intensity and mutagenicity using Salmonella typhimurium TA 98 were examined. Heated glycine model systems containing different sugars increased their mutgenicity ranged from 30 to 372 revertant colonies. After heating for 40 min, mutagenicity was achieved with glycine model systems containing 4 different sugars with by 145, 356, 206, and 369 revertants per plate, respectively. The glycine model systems containing fructose or tagatose were significantly (p<0.05) higher mutagenic activity than glycine model systems containing glucose or galactose after 40 min of heating. The linear regression between Maillard reaction intensity and mutagenic activities (slope=32.38, $R^2=0.93$) indicates that mutagenicity could be fully ascribed to Maillard reaction products.

A new gas-solid reaction model for voloxidation process with spallation

  • Ryu, Je Ir;Woo, Seung Min
    • Nuclear Engineering and Technology
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    • v.50 no.1
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    • pp.145-150
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    • 2018
  • A new methodology, the crack-spallation model, has been developed to analyze gas-solid reactions dominated by crack growth inside of the solid reactant and spallation phenomena. The new model physically represents three processes of the reaction progress: (1) diffusion of gas reactant through pores; (2) growth of product particle in pores; and (3) crack and spallation of solid reactant. The validation of this method has been conducted by comparison of results obtained in an experiment for oxidation of $UO_2$ and the shrinking core model. The reaction progress evaluated by the crack-spallation model shows better agreement with the experimental data than that evaluated by the shrinking core model. To understand the trigger point during the reaction progress, a detailed analysis has been conducted. A parametric study also has been performed to determine mass diffusivities of the gas reactant and volume increase constants of the product particles. This method can be appropriately applied to the gas-solid reaction based on the crack and spallation phenomena such as the voloxidation process.

Engineering Model Design and Implementation Proto Flight Model of Reaction Wheel Assembly Interface Unit for STSAT-2 (과학기술위성 2호 Reaction Wheel Assembly Interface Unit Proto Flight Model 개발)

  • Kim, Se-Il;Gang, Gyeong-In;Lee, Seong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.5
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    • pp.88-92
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    • 2006
  • Proto Flight Model of Reaction Wheel Assembly Interface Unit(RIU) for STSAT-2 was developed. The RIU of STSAT2 has three major functions for interface between satellite system and RWAs. It has switches for RWA main power, communication Mux. and communication line driver.

Modulus of Horizontal Subgrade Reaction in Liquefying Sand by Shaking Table Test (진동대 시험을 통한 액상화되는 지반의 수평지반반력계수에 대한 연구)

  • 박종관;한성길;김상규;이용도
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.255-262
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    • 2000
  • Shaking table tests were peformed to evaluate the subgrade reaction of ground according to the build-up of pore water pressure. Model pile was installed in the sand ground. The acceleration of the model ground, the pore water pressure build-up and displacement of pile were recorded by measuring devices. Subgrade reaction approach based on Winker soil model was applied to obtain the modulus of the horizontal subgrade reaction. The results of analysis show that the reduction factor of the subgrade reaction due to pore pressure increase is about 1 and the horizontal subgrade reaction of liquefied ground is not influenced by the stiffness of pile, a ground acceleration and the intial ground density.

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PATTERN FORMATION IN A GENERAL DEGN-HARRISON REACTION MODEL

  • Zhou, Jun
    • Bulletin of the Korean Mathematical Society
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    • v.54 no.2
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    • pp.655-666
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    • 2017
  • In this paper, we study the pattern formation to a general Degn-Harrison reaction model. We show Turing instability happens by analyzing the stability of the unique positive equilibrium with respect to the PDE model and the corresponding ODE model, which indicate the existence of the non-constant steady state solutions. We also show the existence periodic solutions of the PDE model and the ODE model by using Hopf bifurcation theory. Numerical simulations are presented to verify and illustrate the theoretical results.

A Study on the Ester Interchange Reaction of Dimethyl Naphthalate with Ethylene Glycol (Dimethyl Naphthalate와 Ethylene Glycol의 에스테르 교환반응에 관한 연구)

  • Sho, Soon-Yong;Cheong, Seong-Ihl
    • Polymer(Korea)
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    • v.25 no.1
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    • pp.25-32
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    • 2001
  • The kinetics of ester interchange reaction of dimethyl naphthalate(DMN) with ethylene glycol(EG) has been studied in the range of 180-200 $^{\circ}C$ using zinc and manganese catalysts. The reaction was performed in a semibatch reactor under nonisothermal condition and the degree of reaction was calculated from experimental data of methanol removal rate and reaction temperature. As a reaction model, both the functional group model and the molecular species model were applied and analysed. In case of zinc catalyst, the ratio of reaction rate of methyl hydroxyethyl naphthalate(MHEN) with EG on that of DMN with EG is about 1.4, whereas in case of manganese catalyst the ratio is about 4.3, which implies that the reaction rate is quite dependent on the type of catalyst. In case of zinc catalyst, the reaction order of catalyst concentration on either DMN or MHEN and EG is less than 1, whereas in case of manganese catalyst, the reaction order is larger than 1. The activation energy for zinc and manganese catalyst, irrespective of the type of molecular species, e.g., DMN and MHEN, were found to be 25000 and 28750 cal/mol, respectively. As a result of comparing two reaction model, the molecular species model fits well for the experimental data.

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Kinetics in Phase Transfer Catalysis with Heterogeneous Liquid-Liquid System (액-액 불균일계에서 상이동촉매의 반응속도론 해석)

  • Park, Sang-Wook;Moon, Jin-Bok;Hwang, Kyong-Son
    • Applied Chemistry for Engineering
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    • v.5 no.2
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    • pp.230-237
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    • 1994
  • The reaction conversions of n-butyl acetate in the alkaline hydrolysis of n-butyl acetate by Aliquat 336 were measured in a flat agitator and a dispersion agitator. These measured data was used to analyze the complicated reaction mechanism of the liquid-liquid heterogeneous reaction by a phase transfer catalyst with a pseudo-first order reaction model, a interfacial reaction model and a bulk-body reaction model. The pseudo-firsts order reaction model and the interfacial reaction model could be explained by the experimental data from the dispersion agitator and the bulk-boby reaction model could be explained by those from the flat agitator and the reaction rate constants were $3.1{\times}10^{-4}$, $7.3{\times}10^{-4}$, $6.6m^3/kmol.s$ from these models at $25^{\circ}C$, respectively.

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