• Title/Summary/Keyword: Phase Field Model

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Faults Analysis and Dynamic Simulation Method for Poly-Phase PM Synchronous Motor (다상 영구자석 동기전동기의 고장특성 해석에 관한 연구)

  • Choi, Se-Kwon;Cho, Jun-Seok;Kim, Ju-Yong;Jung, Tae-Uk
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.826_827
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    • 2009
  • This paper introduces major potential faults of Poly-Phase Permanent Magnet Synchronous Motor and their simulation realization methods. The faults of Poly-Phase PM Synchronous Motor, generally, stator turn faults, demagnetizing field. Based on the derived expressions, Poly-Phase PM synchronous Motor simulation model, which is capable of representing stator turn faults, is implemented in Maxwell.

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Phytoremediation and Bioremediation of Land Contaminated by Hydrocarbons: Modeling and Field Applications

  • Sung, Kijune;Corapcioglu, M.Yavuz
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.18-21
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    • 2002
  • Phytoremediation which uses plants to enhance the bioremediation through stimulation of microbial activity and root uptake, has been a topic of increasing interest. Mathematical model were developed that can be applied to various bioremediation methods in the unsaturated zone, especially phytoremediation, for simulating the fate and transport of contaminants under field conditions. A 2-year field study was conducted using 72 (1.5m long and 0.1 m diameter) column lysimeters with four treatments: Johnsongrass; wild rye grass; a rotation of Johnsongrass and wild rye grass; and unplanted fallow conditions. The developed model represented the fate and transport of contaminant both in vegetated and unplanted soils satisfactorily for field applications. Parameters related to the contaminant concentration in the water phase were the main parameters determining the contaminant fate in the vadose zone and indicated that the bioavailability can be the most important factor in the success of phytoremediation as well as bioremediation applications.

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A NEW PRESSURE GRADIENT RECONSTRUCTION METHOD FOR A SEMI-IMPLICIT TWO-PHASE FLOW SCHEME ON UNSTRUCTURED MESHES (비정렬 격자 기반의 물-기체 2상 유동해석기법에서의 압력기울기 재구성 방법)

  • Lee, H.D.;Jeong, J.J.;Cho, H.K.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.15 no.2
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    • pp.86-94
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    • 2010
  • A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation or condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure distribution that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new reconstruction method to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function, a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the CUPID code.

IMPROVEMENT OF A SEMI-IMPLICIT TWO-PHASE FLOW SOLVER ON UNSTRUCTURED MESHES (비정렬 격자계에서의 물-기체 2상 유동해석코드 수치 기법 개선)

  • Lee, H.D.;Jeong, J.J.;Cho, H.K.;Kwon, O.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.380-388
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    • 2010
  • A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation of condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new numerical scheme to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the cupid code.

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The Effect of Differentiated Instruction Design Model for Early Childhood on Development of Teacher's Professionalism (수준별 유아수업설계모형이 유아교사의 전문성 발달에 미치는 효과)

  • Kan, Jin-Sook;Keum, Mi-Suck;Lee, Ching-Chan
    • Journal of Fisheries and Marine Sciences Education
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    • v.24 no.1
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    • pp.56-78
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    • 2012
  • This study which is an alternative exploration for improving the quality level of instruction considering the perception of the teachers in early childhood education field on instructional design is to develop Differentiated Instructional Design Model coincides with the purpose of differentiated instruction curricula and with instructional design principles, and to find out whether the model has significant effect on development of teacher's professionalism. With these purposes, the perception of 343 teachers from early childhood education institutions are investigated, and after component variables are set by drawing the instructional design model available in early childhood education field and reviewing the literature of differentiated instruction model, the Differentiated Instructional design Model for Early Childhood are developed based on FGI(Focus Group Interview) expert evaluation. The experimental study of 88 teachers working in childcare facilities was implemented for effectiveness verification. As a result, first, most teachers consider the priority on making the lesson plans as the development of early childhood and Kindergarten Educational Subjects, and they realize the development of instructional design model which contributes on lesson planning and implementation is much needed. Second, the Differentiated Instructional design Model for Early Childhood are developed, which consists of the cyclic process - pre-lesson phase, lesson implementation phase, and assessment phase -based on development characteristics of early childhood. Third, the experiment of the developed model showed that the scores of experimental group is significantly higher than those of comparative group in knowledge and technique development aspect, and self-understanding development aspect among the aspects of development of teacher's professionalism.

Process Analysis for Rheo-Forming of Aluminum Materials (알루미늄재료의 Rheo-forming을 위한 성형공정해석)

  • Seo P. K.;Jung K. Y.;Jung Y. S.;Kang C. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.05a
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    • pp.124-128
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    • 2001
  • Two-dimensional solidification analysis during rheology forming process of semi-solid aluminum ahoy has been studied Two-phase fluid flow model to investigate the velocity field and temperature distribution is proposed. The unposed mathematical model is applied to the die shape of the two type. To calculate the velocities and temperature fields during rheology forming process, the each governing equation correspondent to the liquid and solid region are adapted. Theoretical model on the basis of the two-phase flow model is the mixture rule of solid and liquid phases. This approach is based on the liquid and solid viscosity.

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NUMERICAL METHOD FOR TWO-PHASE FLOW ANALYSIS USING SIMPLE-ALGORITHM ON AN UNSTRUCTURED MESH (비정렬격자 SIMPLE 알고리즘기반 이상유동 수치해석 기법)

  • Kim, Jong-Tae;Park, Ik-Kyu;Cho, Hyung-Kyu;Kim, Kyung Doo;Jeong, Jae-Jun
    • Journal of computational fluids engineering
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    • v.13 no.4
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    • pp.86-95
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    • 2008
  • For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

NUMERICAL METHOD FOR TWO-PHASE FLOW ANALYSIS USING SIMPLE-ALGORITHM ON AN UNSTRUCTURED MESH (비정렬격자 SIMPLE 알고리즘기반 이상유동 수치해석 기법)

  • Kim, Jong-tae;Park, Ik-Kyu;Cho, Hyung-Kyu;Kim, Kyung-Doo;Jeong, Jae-Jun
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.71-78
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    • 2008
  • For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

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NUMERICAL METHOD FOR TWO-PHASE FLOW ANALYSIS USING SIMPLE-ALGORITHM ON AN UNSTRUCTURED MESH (비정렬격자 SIMPLE 알고리즘기반 이상유동 수치해석 기법)

  • Kim, Jong-Tae;Park, Ik-Kyu;Cho, Hyung-Kyu;Kim, Kyung-Doo;Jeong, Jae-Jun
    • 한국전산유체공학회:학술대회논문집
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    • 2008.10a
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    • pp.71-78
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    • 2008
  • For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

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Nonlinear stability of smart nonlocal magneto-electro-thermo-elastic beams with geometric imperfection and piezoelectric phase effects

  • Faleh, Nadhim M.;Abboud, Izz Kadhum;Nori, Amer Fadhel
    • Smart Structures and Systems
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    • v.25 no.6
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    • pp.707-717
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    • 2020
  • In this paper, analysis of thermal post-buckling behaviors of sandwich nanobeams with two layers of multi-phase magneto-electro-thermo-elastic (METE) composites have been presented considering geometric imperfection effects. Multi-phase METE material is composed form piezoelectric and piezo-magnetic constituents for which the material properties can be controlled based on the percentages of the constituents. Nonlinear governing equations of sandwich nanobeam are derived based on nonlocal elasticity theory together with classic thin beam model and an analytical solution is provided. It will be shown that post-buckling behaviors of sandwich nanobeam in thermo-electro-magnetic field depend on the constituent's percentages. Buckling temperature of sandwich nanobeam is also affected by nonlocal scale factor, magnetic field intensity and electrical voltage.