• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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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.

• Journal of Korean Society for Atmospheric Environment
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• 제8권1호
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• pp.74-83
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• 1992

Photochemical reactions are important for the diurnal variation of the concentrations of air pollutants in the urban atmosphere. A photochemical reaction model was developed, which includes in terms of the effective chemical reaction. Various experimental results were introduced to the construction of model. To verify the applicability of the model, the simulated results were compared with those observed. By comparing the simulated results with those observed, it was shown that those two are in good agreement qualitatively. As a result, the photochemical reaction model which has been developed in this study is found to be useful for the prediction of concentrations of air pollutants in the atmosphere.

• Nuclear Engineering and Technology
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• 제50권1호
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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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제34권5호
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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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.

• Bulletin of the Korean Mathematical Society
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• 제54권2호
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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.

• Polymer(Korea)
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• 제25권1호
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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.

• Applied Chemistry for Engineering
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• 제5권2호
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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.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.746-754
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• 2015

In this study, we investigated the effects of the temperature on the coal/biomass $char-CO_2$ gasification reaction under isothermal conditions of $700{\sim}900^{\circ}C$ using the lignite(Indonesia Eco coal) with biomass (korea cypress). Ni catalysts were impregnated on the coal by the ion-exchange method. Four kinetic models which are shrinking core model (SCM), volumetric reaction model (VRM), random pore model (RPM) and modified volumetric reaction model (MVRM) for gas-solid reaction were applied to the experimental data against the measured kinetic data. The Activation energy of Ni-coal/biomass, non-catalyst coal/biomass $Char-CO_2$ gasification was calculated from the Arrhenius equation.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.833-841
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• 2021

During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.