• Title/Summary/Keyword: Numerical Calculation

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Phase Field Modeling of Graphitization in Ductile Cast Iron by Strip Casting(I);Modeling of Phases with Negligible Solubility (스트립캐스팅한 구상흑연주철 박판의 흑연화 과정에 대한 phase-field 모델링 (I);고용도가 없는 상의 모델링)

  • Kim, Sung-Gyun;Ra, Hyung-Yong
    • Journal of Korea Foundry Society
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    • v.20 no.2
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    • pp.129-140
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    • 2000
  • This study aims at the phase-field modeling of the phase transformation in graphitization of the cast iron. As the first step, we constructed a phase-field model including the phases with negligible solubility. Under the dilute regular solution approximation, a simplified version of the phase-field model was obtained, which can be used for the phase transformation related with the stoichiometric phases. The results from the numerical calculation of the phase-field model was in good agreement with the exact analytic solution. The compositional shift due to Gibbs-Thomson effect can be reproduced within 0.5% error in the numerical calculation. The interface velocity, whereas, in numerical calculation of phase-field model appeared to be 15% larger than that from the analytic solution. This error is due to the shift of the interface position in phase-field model from the position with ${\phi}=0.5$.

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Calculation of DC Characteristics of Stacked BSCCO Wires under Variable External Magnetic field (수치해석을 이용한 BSCCO 적층 선제들의 외부자장 변화에 따른 DC 통전 특성 계산)

  • Lim, Hyoung-Woo;Kang, Myung-Hun;Cha, Guee-Soo;Lee, Hee-Joon
    • Proceedings of the KIEE Conference
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    • pp.53-55
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    • 2007
  • This paper has presented the numerical calculation of fundamental characteristics of the HTS wire by using commercial software. Numerical calculation of the HTS wire's characteristics is able to reduce the time and effort which need to be exerted to obtain hose values experimentally. Results of numerical calculation, such as, critical current of he single and the multi-slacked wire under external magnetic field, were compared with that of experimental results.

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A Study on the Forging of Spur Gears with Internal Serrations (내부세레이션홈을 갖는 스퍼어 기어의 단조에 관한 연구)

  • 최종웅;조해용
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.2
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    • pp.81-89
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    • 1998
  • Numerical calculation tools for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear. square spline, internal serrations. A complex calculation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper the workpiece with 110th external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool from combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with others and the calculated solution are useful to predict the capacity of forging equipment.

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A Study on Numerical Calculation of Gas Migration from the Sanitary Landfill (쓰레기 매립지에서 가스유출 계산에 관한 연구)

  • 이해승
    • Journal of environmental and Sanitary engineering
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    • v.13 no.3
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    • pp.43-51
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    • 1998
  • This study presents a numerical method for calculating gas flow around a sanitary landfill gas vent, when gas flows by pressure. The method described is a three-dimensional compartmental model and includes methods to determine the dimensions for the model. Using the numerical method, controll of press and gases flowing out to the air through final cover soil, and degine of sanitary landfill gas vents.

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Numerical Calculation of Longitudinal Current Distribution in Grounding Electrode for Analyzing the Grounding Impedance (접지임피던스 분석을 위한 접지전극의 전류분포 수치계산)

  • Cho, Sung-Chul;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.1
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    • pp.46-52
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    • 2013
  • The current distribution passing through grounding electrode is required for calculating an impedance of grounding electrode using the electromagnetic field model. In this paper the numerical calculation for currents passing through a grounding electrode as a function of frequency was given. The proposed approach is based on the wire antenna model(AM) in the frequency domain. The Pocklington's equation driven from the wire antenna theory was numerically calculated by the Galerkin's method. The triangle function was applied to both the basis function and the weighting function. The current distribution of a horizontal ground electrode was simulated in MATLAB. Also these results were compared with the data obtained from the CDEGS HIFREQ calculation.

Numerical Calculation and Experiment of Green Water on the Bow Deck in Regular Waves (규칙파 중 선수갑판 Green Water에 대한 수치계산 및 실험)

  • Kim, Yong-Jig;Shin, Ki-Seok
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.4
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    • pp.350-356
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    • 2005
  • Prediction of green water loads acting on the bow deck is au essential part for the design of bow structures against the green water impact. Proper technique of the green water simulation is highly required for the prediction of green water loads. in this paper, the green water flow on bow deck is simulated by FDM(finite difference method). Using the results of green water simulation, impact load on bow deck is calculated. Also, experiments are carried out to compare with the numerical calculation. Through the comparisons between experimental results and numerical results, it is verified that the present numerical tool is adequate as a practical calculation tool for the green water problem.

Numerical Analysis of Acoustic Characteristics in Gas Turbine Combustor with Spatial Non-homogeneity

  • Sohn, Chae-Hoon;Cho, Han-Chang
    • Journal of Mechanical Science and Technology
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    • v.18 no.8
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    • pp.1461-1469
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    • 2004
  • Acoustic characteristics in an industrial gas-turbine combustor are numerically investigated by a linear acoustic analysis. Spatially non-homogeneous temperature field in the combustor is considered in the numerical calculation and the characteristics are analyzed in view of acoustic instability. Acoustic analyses are conducted in the combustors without and with acoustic resonator, which is one of the acoustic-damping devices or combustion stabilization devices. It has been reported that severe pressure fluctuation frequently occurs in the adopted combustor, and the measured signal of pressure oscillation is compared with the acoustic-pressure response from the numerical calculation. The numerical results are in good agreement with the measurement data. In this regard. the phenomenon of pressure fluctuation in the combustor could be caused by acoustic instability. From the numerical results for the combustor with present acoustic resonators installed, the acoustic effects of the resonators are analyzed in the viewpoints of both the frequency tuning and the damping capacity. It is found that the resonators with present specifications are not optimized and thus, the improved specification or design is required.

Modeling of internal wave generation near a shelf slope by ocean finite element method

  • Lee, Kwi-Joo;Joa, Soon-Won;Eom, Ki-Chang
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.42 no.1
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    • pp.38-43
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    • 2006
  • The 3-D modeling of ocean finite element method(OFEM) using $k-{\varepsilon}$ turbulent model and tetrahedron grids has been used to investigate the internal wave generation during the expansion of the deep water from the open sea to the shelf with a simple shape, which can be widely used in the fields of submarine development, ocean environment and meteorology, etc. In this paper, the detailed configuration of internal wave with its length and height and also the distribution of salinity and turbulent kinematic energy, etc. were derived. It is hoped that this OFEM method can be successfully applied to the numerical calculation of internal wave for and the oceanographic problems (tidal flows around underwater hill, plateau, Georges Bank, etc.) and ocean engineering problems(flow past artificial sea reefs) in future.

A Computer Simulation of the Combustion and Flueway of a Pulse Combustion Water Heater (맥동연소온수기의 연소실과 노도의 컴퓨터 시뮬레이션)

  • Kang, Kun;Shin, Sei-Kun;Kim, Min-Sik
    • Solar Energy
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    • v.9 no.3
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    • pp.64-72
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    • 1989
  • In this study, the computer simulation for the heat transfer in pulse combustion water heater is performed. The attention is focused to the effects of the installation of corebuster in the flue tube on heat transfer. The energy equations are established for both wall and gas side in the combustion chamber, flue way, exhaust chamber and muffler, and the numerical calculation is executed. Zone method takes longer computer calculation time compared with semi-zone method. Semi-zone method is chosen for numerical calculation. As a result of this study, it is found that the installation of the core buster in flue tube increases total heat transfer. It is also found that the total heat transfer is increased with the increasing of the ratio of the cross section area of corebuster to that of the flue tube. However, the heat transfer effect is negligible for the area ratio above 0.5.

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