• Title/Summary/Keyword: Numerical Calculation

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Point Particle Approximation for Single and Two Species Diffusion-Influenced Reactions

  • Kim, Hyojoon
    • Bulletin of the Korean Chemical Society
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    • v.34 no.5
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    • pp.1454-1456
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    • 2013
  • The fluctuations in concentrations of reactants dominate the long-time dynamics of the single (A + A ${\rightarrow}$ 0) and two species (A + B ${\rightarrow}$ 0) diffusion-influenced annihilation reactions. Although hierarchical Smoluchowski approaches can provide a systematic and flexible framework to deal with the fluctuation effects, their results are too complicated to be analytically solved. For the efficient numerical calculation of the complicated fluctuation effect terms, we show that the presented point particle approximation is not only practical but also quite accurate for most conditions in diffusion-influenced reaction systems.

Temperature Dependence of Galvanomagnetic Properties in Thin Bi Film

  • Nam, S.W.
    • Journal of Magnetics
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    • v.4 no.4
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    • pp.111-114
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    • 1999
  • Numerical calculation for temperature dependence of galvanomagnetic properties of thin bismuth films is pursued. The quasi-two dimensional system is treated in the perturbation formalism of previous study, where realistic screened potential due to impurity is assumed to be the only scattering channel. The potential is separated into pure two dimensional part and the remaining presumed perturbation part. Relaxation time and mobilities for both electron and hole are evaluated, then temperature dependence of the Hall coefficient and magnetoresistance is obtained. The broad minimum of magnetoresistnace is manifested, and the interpretation under the kinetic theory is made. Thickness dependence of the quantities are also shown, which are in good agreement with the expected quantum size effect.

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Application of rotating polarizer method for small cellgap measurement (회전평광법을 이용한 낮은 셀갭 측정)

  • 김창선;이기동;윤태훈;김재창
    • Korean Journal of Optics and Photonics
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    • v.11 no.3
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    • pp.158-162
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    • 2000
  • Measurement of low cell gap and retardation by using a rotating polarizer method was proposed. For more precise calculation and measurement, we applied a simple numerical calculation and a retardation film that has large retardation value of 1 ~m to measurement system. From experiments, we proved that cell gap and retardation could be measured even though the values of those are so small. small.

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DEVELOPMENT OF CALCULATION METHOD OF SENSITIVITIES FOR LIGHT WATER REACTORS

  • Takeda, Toshikazu;Foad, Basma
    • Nuclear Engineering and Technology
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    • v.45 no.6
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    • pp.753-758
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    • 2013
  • A new method of calculating sensitivity coefficients of core characteristics relative to infinite-dilution cross sections has been developed. Conventional sensitivity coefficients are evaluated for the changes of effective cross sections which are dependent on individual models of core and cell. Therefore a correction has been derived to the conventional sensitivity coefficients based on the perturbation theory. The accuracy of the present method has been verified by comparing numerical results of sensitivity coefficients with a reference Monte-Carlo method.

Gain-Coupled Distributed-Feedback Effects in GaAs/AlGaAs Quantum-Wire Arrays

  • Kim, Tae-Geun;Y. Tsuji;Mutsuo Ogura
    • Journal of the Korean Vacuum Society
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    • v.12 no.S1
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    • pp.52-55
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    • 2003
  • GaAs/AlGaAs quantum-wire (QWR) gain-coupled distributed-feedback (GC-DFB) lasers are fabricated and characterized Constant metalorganic chemical vapor deposition (MOCVD) growth is used to avoid grating overgrowth during the fabrication of DFB structures. Numerical calculation shows large gain anisotropy by optical feedback along the DFB directions near Bragg wavelength. DFB lasing via QWR active gratings is also experimentally achieved.

The Numerical Simulation of Harbor Calmness by Finite Element Method (유한요소법에 의한 항만 정온도의 수치모의)

  • 김남형;허영택
    • Journal of Ocean Engineering and Technology
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    • v.16 no.1
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    • pp.22-26
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    • 2002
  • In this paper, a finite element method is applied to the numerical calculation of the harbor calmness. The mild stop equation as the basic equation is used. The key of this model is that the bottom friction and boundary absorption are imposed. A numerical result is presented and compared with the results obtained from the other numerical analysis. These results are in very well agreement. This method calculating the calmness can be broadly utilized making the new design of harbor and fishing port in the future.

Wake Field Effect from the Undulator Vacuum Chamber in PAL-XFEL

  • Park, Yong-Un
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.151.1-151.1
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    • 2014
  • Wake field effect on the electron beam from the undulator chamber in PAL-XFEL is analyzed. The wake field takeover some energy from the electron beam which will increase the energy spread of the electron beam. This will cause the degradation of the radiation power in PAL-XFEL. To decrease the effect, the surface of the undulator vacuum chamber should be fabricated with 200 nm surface roughness and 5 nm oxidation layer. In this presentation, the numerical calculation of the wake will be shown. Simulation results of the radiation generation in PAL-XFEL also will be presented.

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Practical estimation of the plastic collapse limit of curved pipes subjected to complex loading

  • Yan, A.M.;Nguyen, D.H.;Gilles, Ph.
    • Structural Engineering and Mechanics
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    • v.8 no.4
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    • pp.421-438
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    • 1999
  • In this paper a practical limit load estimating procedure is proposed for general pipe-elbow structures subjected to complex loading (in-plane and out-of-plane bending, internal pressure and axial force). The explicit calculating formulae are presented on the basis of theoretical analysis combined with numerical simulation. Von Mises' yield criterion is adopted in both analytical and numerical calculation. The finite element examination shows that the method provides a simple but satisfactory prediction of pipe structures in engineering plastic analysis.

Spectral analysis of random process

  • Akizuki, Kageo
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.13-20
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    • 1994
  • The spectrum estimation methods of random processes are expressed in this paper. Beginning with the basic theory, non-parametric and parametric methods are overviewed. As to non-parametric method, numerical calculation method is also discussed. As to parametric method, AR model is a very famous and effective model representing random process. Estimation methods of AR parameters which have been proposed are mentioned here. Wavelet analysis is a recently interested technique in signal processing. An application of wavelet analysis is also shown.

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