• 방사성폐기물학회지
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• 제16권3호
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• pp.291-299
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• 2018

파이로 공정에서는 사용후핵연료 관리 공정 개발의 일환으로 산화 우라늄을 고온 용융염 전해질계에서 전기화학적 방법으로 환원시키기 위한 전해환원 공정이 개발되고 있다. 이에 따른 전해환원 공정의 반응기 설계를 위해서는 전기화학적 이론에 기초한 모델이 요구되고 있다. 본 연구에서는 상 분리를 설명하는 phase-field 이론에 기초하여 우라늄 산화물의 전해환원 모사를 위한 1차원 모델이 개발되었다. 모델은 우라늄 산화물 내 산소 원소의 확산과 펠렛 표면에서 전기화학 반응 속도를 나타내는 매개변수를 사용하여 외부로부터 내부로 진행되는 전해환원을 잘 모사하고 있으며 계산 결과 전체 전류는 산소원소의 내부 확산에 크게 의존하는 것으로 나타났다. 전해환원 반응에 대한 모델은 대용량 장치 설계에 최적화된 조건 도출에 활용될 것으로 예상되며 장치 설계가 완료되면 공정 연계 모사에 직접 사용될 것으로 기대된다.

• 한국전산유체공학회지
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• 제12권4호
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• pp.44-53
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been applied to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing very well.

• Journal of Power Electronics
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• 제18권4호
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• pp.1154-1164
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• 2018

In single-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the transfer characteristics, including the output power and transfer efficiency, are significantly influenced by the spatial scales of its coils. As a potential alternative, a three-phase MCR WPT system with cylinder-shaped coils that are excited in a voltage-fed manner has been proposed to satisfy the requirements of compact space. This system adopts a phase-shifted angle control scheme to generate a rotating magnetic field and to realize omnidirectional WPT that is immune to spatial scales. The magnetic field model and equivalent circuit models are built to holistically analyze the system characteristics under different angular misalignments. Research results show that the transfer characteristics can be improved by modulating the phase-shifted angle in each phase. Experiments have also been carried out to evaluate the accuracy of the theoretical analysis and to confirm the validity of the system modeling method.

• Geomechanics and Engineering
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• 제21권5호
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• pp.447-459
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• 2020

This paper aims to investigate the effect of rotation on a micropolar thermoelastic medium with voids problem. The problem is assessed according to three-phase-lag model. The normal mode analysis used to obtain the analytical expressions of the considered variables. The non-dimensional displacement, temperature, Micro rotation, the change in the volume fraction field, and stress of the material are obtained and illustrated graphically. Comparisons are made with the results predicted by two theories; namely three- phase-lag model (3PHL) and Green-Naghdi theory of type III (G-N III). The considered variables were plotted for different values of the rotation parameter, the phase-lag of heat flux and the phase-lag of temperature. The numerical results reveal that the rotation and the phase-lag times significantly influence the distribution of the field quantities. Some particular cases of interest are deduced from the present investigation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
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• pp.368-371
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• 2006

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.243-248
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.

• 전기학회논문지
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• 제66권6호
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• pp.981-987
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• 2017

In this paper, we describe the LPM structure with a two-phase, which is not used previously, and explain its operation principle. In order to predict the accurate performance of LPM reduction model, finite element model was derived and the back EMF of LPM reduction model was measured and compared. In order to investigate the thrust and normal force of the LPM reduction model, a driving circuit capable of applying two-phase pulse currents was constructed and the performance was predicted in conjunction with the finite element analysis model. Finally, the design considering actual LPM size was performed. Since the size of the reduction model is small, the field could be made of a permanent magnet. However, it is almost impossible to manufacture a permanent magnet to match the size and capacity of a real LPM for a vehicle, in terms of cost and writing. Therefore, the actual vehicle LPM was replaced by wound type that generates a magnetic field by applying current to the field winding, and the final model was derived using the reaction surface method.

• 대한기계학회논문집B
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• 제26권6호
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• pp.772-778
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• 2002

A numerical analysis of turbulent gas-particle two-phase flow is performed in conjunction with the experiments of Fackrell ＆ Robins and Raupach & Legg that considered ground-level source and/or elevated source flat plate flow. K-$\omega$ turbulence model is used in order to analyze fully turbulent flow field and the concentration equation with settling velocity is adopted for the concentration field. The model of Einstein and Chien is applied that couples the velocity field and the concentration field. Turbulent eddy viscosity is re-evaluated in this model. The present numerical results have good agreement between the simulation and the experimental data for the mean flow velocities and particle concentrations. While the previous study shows about 27% error in the vicinity of the source of particle concentration, the .present study allows about 14% error. A new turbulent gas-particle flow model developed by this study is able to cut down error by 13% at a near source.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.372-376
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• 2014

This study is on acoustic radiation efficiency of a tiffened cylindrical model in water-multi-excitation with phase difference using commercial numerical program ABAQUS and SYSNOISE. When the stiffened cylindrical model is under multi-excitation with phase difference, the surface vibration field is variated with phase difference of excitation. By this different surface vibration field, the acoustic radiation efficiency is also variated with phase difference of excitation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.18-21
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• 2002

We present a phase covariance model that can well represent stimulus intensity as well af feature binding (i.e., covariance). The model is represented by complex neural equations, which is a mean field model of stochastic neural model such as Boltzman machine and sigmoid belief networks.