• 제목/요약/키워드: Direct Simulation Monte Carlo

검색결과 171건 처리시간 0.036초

A rapid and direct method for half value layer calculations for nuclear safety studies using MCNPX Monte Carlo code

  • Tekin, H.O.;ALMisned, Ghada;Issa, Shams A.M.;Zakaly, Hesham M.H.
    • Nuclear Engineering and Technology
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    • 제54권9호
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    • pp.3317-3323
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    • 2022
  • Half Value Layer calculations theoretically need prior specification of linear attenuation calculations, since the HVL value is derived by dividing ln(2) by the linear attenuation coefficient. The purpose of this study was to establish a direct computational model for determining HVL, a vital parameter in nuclear radiation safety studies and shielding material design. Accordingly, a typical gamma-ray transmission setup has been modeled using MCNPX (version 2.4.0) general-purpose Monte Carlo code. The MCNPX code's INPUT file was designed with two detection locations for primary and secondary gamma-rays, as well as attenuator material between those detectors. Next, Half Value Layer values of some well-known gamma-ray shielding materials such as lead and ordinary concrete have been calculated throughout a broad gamma-ray energy range. The outcomes were then compared to data from the National Institute of Standards and Technology. The Half Value Layer values obtained from MCNPX were reported to be highly compatible with the HVL values obtained from the NIST standard database. Our results indicate that the developed INPUT file may be utilized for direct computations of Half Value Layer values for nuclear safety assessments as well as medical radiation applications. In conclusion, advanced simulation methods such as the Monte Carlo code are very powerful and useful instruments that should be considered for daily radiation safety measures. The modeled MCNPX input file will be provided to the scientific community upon reasonable request.

시뮬레이션과 네트워크 축소기법을 이용한 네트워크 신뢰도 추정

  • 서재준;전치혁
    • ETRI Journal
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    • 제14권4호
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    • pp.19-27
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    • 1992
  • Since. as is well known, direct computation of the reliability for a large-scaled and complex net work generally requires exponential time, a variety of alternative methods to estimate the network reliability using simulation have been proposed. Monte Carlo sampling is the major approach to estimate the network reliability using simulation. In the paper, a dynamic Monte Carlo sampling method, called conditional minimal cut set (CMCS) algorithm, is suggested. The CMCS algorithm simulates a minimal cut set composed of arcs originated from the (conditional) source node until s-t connectedness is confirmed, then reduces the network on the basis of the states of simulated arcs. We develop the importance sampling estimator and the total hazard estimator and compare the performance of these simulation estimators. It is found that the CMCS algorithm is useful in reducing variance of network reliability estimator.

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대역확산 통신시스템에서 다중 적응 필터 뱅크를 이용한 간섭신호 제거 시스템 성능 분석 (On the Performance of Interference Excision Scheme using Multiple Adaptive Filter Banks in Spread Spectrum Communication Systems)

  • 박재오;이정재
    • 한국정보통신학회논문지
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    • 제4권3호
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    • pp.653-660
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    • 2000
  • 본 논문에서는 대역확산 통신을 위하여 웨이브렛 패킷 영역에서 다중적응필터뱅크를 이용하여 간섭신호를 제거할 수 있는 적응간섭제거기를 제안하고 Monte-Carlo 시뮬레이션을 이용하여 AWGN과 간섭채널에서 LMS와 RLS 적응알고리즘이 적용된 간섭제거기에 따른 대역확산통신시스템의 성능을 분석하였다.

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분자간 충돌과정에 따른 병진-회전-진동에너지의 이완율 (The Effect of the Collision Process Between Molecules on the Rates of Thermal Relaxation of the Translational-Rotational-Vibrational Energy Exchange)

  • 허중식
    • 대한기계학회논문집B
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    • 제28권12호
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    • pp.1494-1500
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    • 2004
  • A zero-dimensional direct simulation Monte Carlo(DSMC) model is developed for simulating diatomic gas including vibrational kinetics. The method is applied to the simulation of two systems: vibrational relaxation of a simple harmonic oscillator and translational-rotational-vibrational energy exchange process under heating and cooling. In the present DSMC method, the variable hard sphere molecular model and no time counter technique are used to simulate the molecular collision kinetics. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies.

몬테카를로 시뮬레이션을 이용한 직접부하제어의 제어지원금 산정 (Determination of Incentive Level of Direct Load Control using Monte Carlo Simulation with Variance Reduction Technique)

  • 정윤원;박종배;신중린;채명석
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2004년도 하계학술대회 논문집 A
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    • pp.666-670
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    • 2004
  • This paper presents a new approach for determining an accurate incentive levels of Direct Load Control (DLC) program using sequential Monte Carlo Simulation (MCS) techniques. The economic analysis of DLC resources needs to identify the hourly-by-hourly expected energy-not-served resulting from the random outage characteristics of generators as well as to reflect the availability and duration of DLC resources, which results the computational explosion. Therefore, the conventional methods are based on the scenario approaches to reduce the computation time as well as to avoid the complexity of economic studies. In this paper, we have developed a new technique based on the sequential MCS to evaluate the required expected load control amount in each hour and to decide the incentive level satisfying the economic constraints. And also the proposed approach has been considered multi-state as well as two-state of the generating units. In addition, we have applied the variance reduction technique to enhance the efficiency of the simulation. To show the efficiency and effectiveness of the suggested method the numerical studies have been performed for the modified IEEE reliability test system.

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분자드래그펌프의 압축 밀 배기특성 해석 (Direct Simulation of Compression and Pumping Characteristics for a Gaede-Type Drag Pump)

  • 이영규;이진원
    • 한국진공학회지
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    • 제4권4호
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    • pp.343-349
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    • 1995
  • 게데형 분자드래그펌프의 배기특성을 강구(hard sphere)분자모델과 NTC(No Time Counter)충돌 scheme을 이용한 직접모사 법의 하나인 DSMC(direct simulation Monte Carlo)방법을 이용하여 해석하였다. 해석에 사용된 모델은 높이가 일정하고, 길이가 높이의 1~3000배 사이인 이차원 채널이다. 자유분자영역으로부터 연속체 영역까지의 영역에서 최대압축비와 배기속도를 계산하였다. 계산결과 기존의 최대압축비 이론 결과는 채널내의 압력변화가 클 때는 큰 오차를 유발하는 것을 알 수 있었고, 유동방향의 기체분자의 통과확률은 채널 길이와 출구압력에 관계없이 거의 일정한 값을 갖는다는 것을 발견하였다.

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A Goneral Procedure for Testing Equivalence

  • Sung Nae Kyung
    • Communications for Statistical Applications and Methods
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    • 제5권2호
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    • pp.491-501
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    • 1998
  • Motivated by bioequivalence studies which involve comparisons of pharmaceutically equivalent dosage forms, we propose a more general decision rule for showing equivalence simultaneously between multiple means and a control mean. Namely, this testing procedure is concerned with the situation in that one must make decisions as to the bioequivalence of an original drug product and several generic formulations of that drug. This general test is developed by considering a spherical confidence region, which is a direct extension of the usual t-based confidence interval rule formally approved by the U.S. Food and Drug Administration. We characterize the test by the probability of rejection curves and assess its performance via Monte-Carlo simulation. Since the manufacturer's main concern is the proper choice of sample sizes, we provide optimal sample sizes from the Monte-Carlo simulation results. We also consider an application of the generalized equivalence test to a repeated measures design.

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FHSS 및 DSSS 방식 소출력 무선기기간 간섭분석에 관한 연구 (A study on interference analysis between FHSS atd DSSS short range radio devices)

  • 최재혁;구성완;정규일;김진영
    • 한국정보통신설비학회:학술대회논문집
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    • 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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    • pp.242-247
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    • 2009
  • In this paper, we investigate interference between short-range radiocommunication devices (SRDs) with frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-Carlo (MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate (BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than bandwidth does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

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원판형 드래그펌프 회전자와 고정자 사이의 간극이 성능에 미치는 영향 (Effect of Vertical Clearance Between a Rotor and Stater of a Disk-Type Drag Pump on the Performance)

  • 권명근;황영규
    • 대한기계학회논문집B
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    • 제28권12호
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    • pp.1501-1510
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    • 2004
  • The pumping characteristics of a single-stage disk-type drag pump (DTDP) are calculated for the variation of the vertical clearance between a rotor and stator by the three-dimensional direct simulation Monte Carlo (DSMC) method. The gas flow mainly belongs to the molecular transition flow region. Spiral channels of a DTDP are cut on the both the upper and lower sides of a rotating disk, but a stationary disk is planar. The interaction between molecules is described by the variable hard-sphere model. The no time counter method is used as a collision sampling technique. The vertical clearance has a significant effect on the pumping performance. Experiments are performed under the outlet pressure range of 0.4∼533 Pa. When the numerical results are compared with the experimental data, the numerical results agree well quantitatively

원판형 드래그펌프의 성능특성에 관한 연구 (A Study on the Performance Characteristics of a Disk-type Drag Pump)

  • 황영규;허중식
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집E
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    • pp.643-648
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    • 2001
  • The direct simulation Monte Carlo(DSMC) method is applied to investigate steady and unsteady flow fields of a single-stage disk-type drag pump. Two different kinds of pumps are considered: the first one is a rotor-rotor combination, and the second one is a rotor-stator combination. The pumping channels are cut on a rotor and stator. The rotor and stator have 10 Archimedes' spiral blades, respectively. In the present DSMC method, the variable hard sphere model is used as a molecular model, and the no time counter method is employed as a collision sampling technique. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies. The DSMC results are in good agreement with the experimental data.

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