• Title/Summary/Keyword: Monte-Carlo simulations

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Adjustment for Multimorbidity in Estimations of the Burden of Diseases Using Korean NHIS Data

  • Shin, Yoonhee;Choi, Eun Jeong;Park, Bomi;Lee, Hye Ah;Lee, Eun-Kyung;Park, Hyesook
    • Journal of Preventive Medicine and Public Health
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    • v.55 no.1
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    • pp.28-36
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    • 2022
  • The current multimorbidity correction method in the Global Burden of Disease studies assumes the independent occurrence of diseases. Those studies use Monte-Carlo simulations to adjust for the presence of multiple disease conditions for all diseases. The present study investigated whether the above-mentioned assumption is reasonable based on the prevalence confirmed from actual data. This study compared multimorbidity-adjusted years of lived with disability (YLD) obtained by Monte-Carlo simulations and multimorbidity-adjusted YLD using multimorbidity prevalence derived from National Health Insurance Service data. The 5 most common diseases by sex and age groups were selected as diseases of interest. No significant differences were found between YLD estimations made using actual data and Monte-Carlo simulations, even though assumptions about the independent occurrence of diseases should be carefully applied. The prevalence was not well reflected according to disease characteristics in those under the age of 30, among whom there was a difference in YLD between the 2 methods. Therefore, when calculating the burden of diseases for Koreans over the age of 30, it is possible to calculate the YLD with correction for multimorbidity through Monte-Carlo simulation, but care should be taken with under-30s. It is useful to apply the efficiency and suitability of calibration for multiplicative methods using Monte-Carlo simulations in research on the domestic disease burden, especially in adults in their 30s and older. Further research should be carried out on multimorbidity correction methodology according to the characteristics of multiple diseases by sex and age.

Development and verification of a novel system for computed tomography scanner model construction in Monte Carlo simulations

  • Ying Liu;Ting Meng ;Haowei Zhang ;Qi Su;Hao Yan ;Heqing Lu
    • Nuclear Engineering and Technology
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    • v.54 no.11
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    • pp.4244-4252
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    • 2022
  • The accuracy of Monte Carlo (MC) simulations in estimating the computed tomography radiation dose is highly dependent on the accuracy of CT scanner model. A system was developed to observe the 3D model intuitively and to calculate the X-ray energy spectrum and the bowtie (BT) filter model more accurately in Monte Carlo N-particle (MCNP). Labview's built-in Open Graphics Library (OpenGL) was used to display basic surfaces, and constructive solid geometry (CSG) method was used to realize Boolean operations. The energy spectrum was calculated by simulating the process of electronic shooting and the BT filter model was accurately modeled based on the calculated shape curve. Physical data from a study was used as an example to illustrate the accuracy of the constructed model. RMSE between the simulation and the measurement results were 0.97% and 0.74% for two filters of different shapes. It can be seen from the comparison results that to obtain an accurate CT scanner model, physical measurements should be taken as the standard. The energy spectrum library should be established based on Monte Carlo simulations with modifiable input files. It is necessary to use the three-segment splicing modeling method to construct the bowtie filter model.

A Study of Germanium Substrate Vacancy Clustering Formation using Monte Carlo Method (Monte Carlo방법을 이용한 Germanium 기판의 결공형 클러스터링 형성에 대한 연구)

  • Lee, Jun-Ha
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.2
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    • pp.45-48
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    • 2011
  • In this paper, vacancy clustering formation and diffusion of germanium substrate was studied. The analysis method was adopted Monte Carlo method. At temperatures higher than melting point, fewer clusters formed, but there was less variation in the number of clusters than at lower temperatures, as the time increased. Equilibrium diffusivities in the clustering region were $10^2$ lower than those of free vacancies in the initial stage of kinetic lattice Monte Carlo simulations. They were expressed according to three temperature regimes: at temperatures above 1,100 K, at temperatures of 1,100-900 K, and at temperatures below 900 K. The effective mean migration energy, 1.1 eV, closely coincided with that of the 1.0-1.2 eV in experiments.

Optimal Gamma Irradiation Using Monte Carlo Simulations on Wooden Cultural Properties, Gimjeotgae (목재 유물 김젖개의 몬테카를로 방법을 이용한 감마선 조사)

  • Yoon, Minchul;Choi, Jong-il;Lee, Yun Jong;Lim, Kil-Sung;Lee, Ju-Woon
    • Journal of Radiation Industry
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    • v.6 no.1
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    • pp.95-100
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    • 2012
  • In this study, there has been investigated the simulation of irradiation dose using Monte Carlo methodology for the biological control of wooden cultural property. In the evaluation of fungal contamination on wooden cultural properties, Cladosporium tenuissimum, Aspergillus versicolor, Penicillium sp. were mainly identified from the Gimjeotgae. But these microorganisms were completely inactivated by 20 kGy gamma-rays. For dosimetry simulation of wooden cultural properties, Monte Carlo methodology with MCNP was used. The radiation absorbed dose distribution was predicted at 8.2~18.9 kGy. These results show that irradiation is effective for biologic control of wooden cultural properties and Monte Carlo methodology is useful for non-destructive conservation and preservation of wooden cultural properties.

Application of quasi-Monte Carlo methods in multi-asset option pricing (준난수 몬테칼로 방법을 이용한 다중자산 옵션 가격의 추정)

  • Mo, Eun Bi;Park, Chongsun
    • Journal of the Korean Data and Information Science Society
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    • v.24 no.4
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    • pp.669-677
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    • 2013
  • Quasi-Monte Carlo method is known to have lower convergence rate than the standard Monte Carlo method. Quasi-Monte Carlo methods are using low discrepancy sequences as quasi-random numbers. They include Halton sequence, Faure sequence, and Sobol sequence. In this article, we compared standard Monte Carlo method, quasi-Monte Carlo methods and three scrambling methods of Owen, Faure-Tezuka, Owen-Faure-Tezuka in valuation of multi-asset European call option through simulations. Moro inversion method is used in generating random numbers from normal distribution. It has been shown that three scrambling methods are superior in estimating option prices regardless of the number of assets, volatility, and correlations between assets. However, there are no big differences between them.

Monte Carlo Simulation of Densification during Liquid-Phase Sintering

  • Lee, Jae Wook
    • Journal of the Korean Ceramic Society
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    • v.53 no.3
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    • pp.288-294
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    • 2016
  • The densification process during liquid-phase sintering was simulated by Monte Carlo simulation. The Potts model, which had been applied to coarsening during liquid-phase sintering, was modified to include vapor particles. The results of two- and threedimensional simulations showed a temporal decrease in porosity, in other words, densification, and an increase in the average size of pores. The results also showed growth of solid grains and the effect of wetting angle on microstructure.

Domain Decomposition Strategy for Pin-wise Full-Core Monte Carlo Depletion Calculation with the Reactor Monte Carlo Code

  • Liang, Jingang;Wang, Kan;Qiu, Yishu;Chai, Xiaoming;Qiang, Shenglong
    • Nuclear Engineering and Technology
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    • v.48 no.3
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    • pp.635-641
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    • 2016
  • Because of prohibitive data storage requirements in large-scale simulations, the memory problem is an obstacle for Monte Carlo (MC) codes in accomplishing pin-wise three-dimensional (3D) full-core calculations, particularly for whole-core depletion analyses. Various kinds of data are evaluated and quantificational total memory requirements are analyzed based on the Reactor Monte Carlo (RMC) code, showing that tally data, material data, and isotope densities in depletion are three major parts of memory storage. The domain decomposition method is investigated as a means of saving memory, by dividing spatial geometry into domains that are simulated separately by parallel processors. For the validity of particle tracking during transport simulations, particles need to be communicated between domains. In consideration of efficiency, an asynchronous particle communication algorithm is designed and implemented. Furthermore, we couple the domain decomposition method with MC burnup process, under a strategy of utilizing consistent domain partition in both transport and depletion modules. A numerical test of 3D full-core burnup calculations is carried out, indicating that the RMC code, with the domain decomposition method, is capable of pin-wise full-core burnup calculations with millions of depletion regions.

In-line (α,n) source sampling methodology for monte carlo radiation transport simulations

  • Griesheimer, David P.;Pavlou, Andrew T.;Thompson, Jason T.;Holmes, Jesse C.;Zerkle, Michael L.;Caro, Edmund;Joo, Hansem
    • Nuclear Engineering and Technology
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    • v.49 no.6
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    • pp.1199-1210
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    • 2017
  • A new in-line method for sampling neutrons emitted in (${\alpha}$,n) reactions based on alpha particle source information has been developed for continuous-energy Monte Carlo simulations. The new method uses a continuous-slowing-down model coupled with (${\alpha}$,n) cross section data to precompute the expected neutron yield over the alpha particle lifetime. This eliminates the complexity and computational cost associated with explicit charged particle transport. When combined with an integrated alpha particle decay source sampling capability, the proposed method provides an efficient and accurate method for sampling (${\alpha}$,n) neutrons based solely on nuclide inventories in the problem, with no additional user input required. Results from several example calculations show that the proposed method reproduces the (${\alpha}$,n) neutron yields and energy spectra from reference experiments and calculations.

Design and performance prediction of large-area hybrid gamma imaging system (LAHGIS) for localization of low-level radioactive material

  • Lee, Hyun Su;Kim, Jae Hyeon;Lee, Junyoung;Kim, Chan Hyeong
    • Nuclear Engineering and Technology
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    • v.53 no.4
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    • pp.1259-1265
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    • 2021
  • In the present study, a large-area hybrid gamma imaging system was designed by adopting coded aperture imaging on the basis of a large-area Compton camera to achieve high imaging performance throughout a broad energy range (100-2000 keV). The system consisting of a tungsten coded aperture mask and monolithic NaI(Tl) scintillation detectors was designed through a series of Geant4 Monte Carlo radiation transport simulations, in consideration of both imaging sensitivity and imaging resolution. Then, the performance of the system was predicted by Geant4 Monte Carlo simulations for point sources under various conditions. Our simulation results show that the system provides very high imaging sensitivity (i.e., low values for minimum detectable activity, MDA), thus allowing for imaging of low-activity sources at distances impossible with coded aperture imaging or Compton imaging alone. In addition, the imaging resolution of the system was found to be high (i.e., around 6°) over the broad energy range of 59.5-1330 keV.

Molecular Modeling of the Chiral Recognition of Propranolol Enantiomers by a β-Cyclodextrin

  • Kim, Hyun-myung;Jeong, Karp-joo;Lee, Sang-san;Jung, Seun-ho
    • Bulletin of the Korean Chemical Society
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    • v.24 no.1
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    • pp.95-98
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    • 2003
  • Enantioselectivity of the propranolol on β-cyclodextrin was simulated by molecular modeling. Monte Carlo (MC) docking and molecular dynamics (MD) simulations were applied to investigate the molecular mechanism of enantioselective difference of both enantiomeric complexes. An energetic analysis of MC docking simulations coupled to the MD simulations successfully explains the experimental elution order of propranolol enantiomers. Molecular dynamics simulations indicate that average energy difference between the enantiomeric complexes, frequently used as a measure of chiral recognition, depends on the length of the simulation time. We found that, only in case of much longer MD simulations, noticeable chiral separation was observed.