• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.119-125
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• 1999

This research has been studied in terms of investigating the reaction behavior of pyrite with a cyclone reactor. The Mathematical model has developed pyrite oxidation and lime sulfation in this reactor. The model assumes a chemical control shrinking core behavior for the pyrite and a fluid film control shrinking core behavior for the lime. The model was solved and characterized numerically. Experiments have been performed to study the influence of reaction parameters such as reactor temperatures, pyrite particle sizes, air flow rates, feeding rates, and mixing ratio of pyrite and lime. The oxidation and sulfation products were characterized chemically and physically.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.105-114
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• 2004

This study investigated the thermal behavior of the nuclear graphite waste generated from the decommissioning of the Korean nuclear research reactor, The first part study investigated the decomposition rate of the nuclear graphite waste up to $1000^{\circ}C$ under various oxygen partial pressures using a thermo-gravimetric analyzer (TGA). Tested graphite waste sample not easily destroyed in the oxygen-deficient condition. However, the gas-solid oxidation reaction was found to be very effective in the presence of oxygen. No significant amount of the product of incomplete combustion was formed even in the limited oxygen concentration of 4% $O_2$. The influence of temperature and oxygen partial pressure was evaluated by the theoretical model analysis of the thermo-gravimetric data. The activation energy and the reaction order of graphite oxidation were evaluated as 128 kJ/mole and 1.1, respectively. The second part of this study investigated the behavior of radioactive elements under graphite oxidation atmosphere using thermodynamic equilibrium model. $^{22}Na$, $^{134}Cs$ and $^{137}Cs$ were found be the semi-volatile elements. Since volatile uranium species can be formulated at high temperatures above $1050^{\circ}C$, the temperature of incinerator furnace should be minimized. Other corrosion/activation products, fission products and uranium were found to be the non-volatile species.

• The Journal of the Korean dental association
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• v.54 no.1
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• pp.27-38
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• 2016

Objectives: This study evaluated the outcomes of continuing professional education in implant dentistry using Kirkpatrick's four-level evaluation model. Material and methods: The study was carried out through a questionnaire distributed to dentists who attended a continuing professional education in implant dentistry, 2008~2012. They were asked to fill out questionnaires at least 6 months after its completion. Results: Mean ages of total 23 dentist was $44.8^{\circ}{\ae}8.2$. Mean period after completion of education was $2.7^{\circ}{\ae}1.2$. Knowledge (level 2) (r=0.71, p<0.01) and behavior (level 3) (r=0.68, p<0.01) was positively correlated with topic and methods of education in reaction (level 1). Behavior was positively correlated with knowledge (r=0.79, p<0.01). Result (level 4) was positively correlated with knowledge (r=0.64, p<0.01) and behavior (r=0.86, p<0.01). Conclusion: Reaction affects on knowledge, behavior and result in order.

• Resources Recycling
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• v.23 no.6
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• pp.47-53
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• 2014

Effective treatment and energy conversion technologies are necessary due to the ban of the dumping of organic waste including the sewage sludge. In this study, the kinetics of pyrolysis and combustion were derived in a TGA and thermobalance reactor, which is essential for thermal conversion of sewage sludge to energy. Three steps are shown for the pyrolysis in TGA and the different pre-exponential factors and activation energies are derived depending on the temperature range. Three models of gassolid reaction were applied to the reaction kinetics analysis for the combustion of sewage sludge char and shrinking core model was an appropriated model. Apparent activation energy and pre-exponential factor were evaluated and the effect of oxygen partial pressure was examined.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.156.1-156.1
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• 2011

It is of great importance to predict operating parameter characteristics of an integrated fuel processor by the increased life-time and system performance. In this study, computational analysis is performed to gain fundamental insights on transport phenomena and chemical reactions in reformer which consists of preheating, steam reforming, and water gas shift reaction beds. Also, a top-fired burner locates inside of the reforming system. The combustor is providing thermal energy necessary for the steam reforming bed which is a endothermic catalytic reactor. Two-dimensional numerical model of the integrated fuel processing system is introduced for the analysis of heat and mass transport phenomena as well as surface kinetics and catalytic process. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Subsequently, parameter study using the validated steam methane reforming model was conducted by considering operating parameters, i.e. steam to carbon ratio and temperature.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.211-220
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• 2004

It is well known that the geometry of the articular surface has a major role in determining the position of articular contact and the lines of action for the contact forces. The contact force calculation of the knee joint under the effect of sliding and rolling is one of the most challenging issues in this field. We present a 3-D human knee joint model including sliding and rolling motions and major ligaments to calculate the lateral and medial condyle contact forces from the recovered total internal reaction force using inverse dynamic contact modeling and the Least-Square method. As results, it is believed that the patella, muscles and tendon affect a lot for the internal reaction forces at the initial heel contact stage. With increasing flexion angles during gait, the decreasing contact area is progressively shifted to the posterior direction on the tibia plateau. In addition, the medial side contact force is larger than the lateral side contact force in the knee joint during normal human walking. The total internal forces of the knee joint are reasonable compared to previous studies.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.233-239
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• 2003

The present study has numerically investigated the combustion processes in the solid propellant rocket engine. The two step global reaction model for condensed phase and five step global reaction mechanism for gas phase are adopted to predict the detailed flame structure near double-base solid propellant surface. The turbulence-chemistry interaction is represented by the PaSR(Partially Stirred Reactor) model. To reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect, the Low Reynolds number k-$\varepsilon$ turbulent model is employed. Based on numerical results, the detailed discussion has been made for the turbulent combustion processes and transient behavior of pressure and temperature fields in the solid propellant rocket engine.

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.411-420
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• 1997

QUAL2E-AFOSM model is developed to forecast the water quality by reliability analysis in the Nakdong River. A varied-flow analysis is performed for the reach of Waegwan to Mulgeum to estimate hydraulic parameters. An optimization technique by BFGS method is applied to determine the optimum reaction parameters and calibrations and verifications are performed based on these parameters. A reliability analysis for the stochastic analysis in a river is studied using the AFOSM method. The variations of water quality and discharge in the headwater, tributaries, and reaction coefficients are considered. Risks of violating existing water quality standards at several loactions in the Nakdong River are computed by using the QUAL2E-AFOSM method. The computed results computed by QUAL2E-AFOSM model agree with those of the Monte-Carlo method in QUAL2EU model.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.143-147
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• 2007

Kerosene and diesel are compounded fuels with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focuses on the prediction of the non-equilibrium reaction of fuel-rich combustion with detailed kinetics developed by Dagaut using PSR(perfectly stirred reactor) assumption. In Dagaut's surrogate model for kerosene and diesel, chemical kinetics consists of 2352 reaction steps with 298 chemical species. Also, Frenklach's soot model was implemented along with detailed kinetics to calculate the gas properties of fuel rich combustion efflux.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.749-760
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• 2005

This study examines the local ozone photochemistry in the urban air. The photochemical formation and destruction of ozone was modeled using a photochemical box model. For the model prediction of ozone budget, measurements were carried out from an urban monitoring station in Seoul ($37.6^{\circ}N,\;127^{\circ}E$), Korea for intensive sampling time period (Jun. $1\~15$, 2003). Photochemical process is likely to play significant role in higher ozone concentrations during the sampling period. The results of model simulation indicated that photochemical ozone production pathway was the reaction of NO with $HO_2$ while ozone destruction was mainly controlled by a photochemical destruction pathway, a reaction of $H_2O$ with $O(^1D).$ The contribution of NMHCs to formation and destruction of ozone in the urban was significant. This was entirely different from remote marine environment. The rates of net photochemical ozone production ranged from 0.1 to 1.3 ppbv $h^{-1}$ during the study period.