• Title, Summary, Keyword: 몬테 칼로법

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Evaluation of Performance of Atmospheric Re-Entry System for the Uncertainties Using the Monte-Carlo Simulation (몬테-칼로 모의실험을 이용한 대기권 재진입 시스템의 불확실성 성능 평가)

  • Lee, Dae-Woo;Cho, Kyeum-Rae;Oh, Se-Jong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.7
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    • pp.51-60
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    • 2002
  • The Monte-Carlo simulation of statistical analysis is used to investigate the final conditions of states as well as the footprint boundaries resulting from the atmospheric re-entry dispersions. The re-entry dispersions in this paper are specified by a $7\times7$ covariance matrix of latitude, longitude, altitude, bank angle, flight path angle, heading error, and range at entry velocity. The error sources that affect these at re-entry for a deboost are the uncertainties associated with atmospheric density and temperature, initial errors, wind, and estimation error of aerodynamic coefficients. Using $3{\sigma}_n$ deviations of these errors and a nominal flight trajectory, the covariance matrix of state variables can be determined by performing a trajectory error analysis. Major considerations in the application of the Monte-Carlo method are the simulation of perturbed trajectories, bank reversal, and determination of the impact points for each of these trajectories. This paper analyzes the results of uncertainties from the viewpoint of aero-coefficients and bank reversal.

A Monte-Carlo method and Boltzmann Equation analysis on the electron swarm parameter in SiH$_4$+Ar mixtures gas. ($SiH_4+Ar$ 혼합기체의 전자군 파라미터에 대한 볼츠만 방정식 및 몬테 칼로법 해석)

  • 김대연;하성철
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.387-390
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    • 1999
  • Electron swarm parameterdthe drift velocity and longitudinal diffusion coefficienthn $SiH_4-Ar$ mixtures containing 0.5% and 5% monosilane were measured using over the range of E/N from 0.01 to 300 Td at room temperature. Electron swarm parameters in argon were drastically changed by adding a small amount of monosilane. The electron drift velocity in both mixtures showed unusual behaviour against E/N. It had negative slope in the medium range of E/N, yet the slope was not smooth but contained a small hump. The longitudinal diffusion coefficient also showed a corresponding feature in its dependence on E/N. A two-tern approximation of the Boltzmann equation analysis and Monte Carlo simulation have been used to study electron transport coefficients.

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Application of Pulse Pile-Up Correction Spectrum to the Library Least-Squares Method (펄스 중첩 보정 스펙트럼의 라이브러리 최소자승법에의 이용)

  • Lee, Sang-Hoon
    • Journal of Radiation Protection and Research
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    • v.31 no.4
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    • pp.173-179
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    • 2006
  • The Monte Carlo simulation code CEARPPU has been developed and updated to provide pulse pile-up correction spectra for high counting rate cases. For neutron activation analysis, CEARPPU correction spectra were used in library least-squares method to give better isotopic activity results than the convention library least-squares fitting with uncorrected spectra.

Simulation of Silicon Carbide Converted Graphite by Chemical Vapor Reaction (Ⅰ) (화학적 기상 반응에 의한 탄화규소 피복 흑연의 시뮬레이션(Ⅰ))

  • Lee, Joon-Sung;Choi, Sung-Churl
    • Journal of the Korean Ceramic Society
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    • v.38 no.9
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    • pp.846-852
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    • 2001
  • A two-dimensional Monte Carlo simulation has been used to investigate the effect of the reaction temperature on the formation of the silicon carbide conversion layer near the surface of graphite substrate The carbothermal reduction of silica is the reaction mechanism of silicon carbide formation on graphite substrate by chemical vapor reaction methods. The chemical composition of silicon carbide conversion layer gradually changes from carbon to silicon carbide because gaseous reactants diffuse through micropores within graphite substrate and react with carbon at the surface of inner pores. The simulation was carried out under the condition of reaction temperature at 1900K, 2000K, 2100K and 2200K for 500MCS. It was found from the results of simulation that the thickness of silicon carbide conversion layer increases with reaction temperature.

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A study on the electron transport coefficients using monte carlo method in argon gas (몬테칼로법을 이용한 Ar기체의 전자수송계수에 관한 연구)

  • 하성철;전병훈
    • Electrical & Electronic Materials
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    • v.8 no.6
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    • pp.685-692
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    • 1995
  • The electron transport coefficients in argon gas is studied over the range of E/N values from 85 to 566 Td by the Monte Carlo method considering the latest cross section data. The result of the Monte Carlo method analysis shows that the value of the electron transport coefficients such as the electron drift velocity, the ratio of the longitudinal and transverse diffusion coefficients to the mobility. It is also found that the electron transport coefficients calculated by the two-term approximation analysis agree well with those by Monte Carlo calculation. The electron energy distributions function were analysed in argon at E/N=283, and 566 Td for a case of the equilibrium region in the mean electron energy. A momentum transfer cross section for the argon atom which was consistent with both of the present electron transport coefficients was derived over the range of mean electron energy from 10.3 to 14.5 eV, also suggested as a set of electron cross section for argon atom. The validity of the results obtained has been confirmed by a Monte Carlo simulation method.

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