• Title/Summary/Keyword: MC simulation

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Development and Evaluation of a Thimble-Like Head Bolus Shield for Hemi-Body Electron Beam Irradiation Technique

  • Shin, Wook-Geun;Lee, Sung Young;Jin, Hyeongmin;Kim, Jeongho;Kang, Seonghee;Kim, Jung-in;Jung, Seongmoon
    • Journal of Radiation Protection and Research
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    • v.47 no.3
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    • pp.152-157
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    • 2022
  • Background: The hemi-body electron beam irradiation (HBIe-) technique has been proposed for the treatment of mycosis fungoides. It spares healthy skin using an electron shield. However, shielding electrons is complicated owing to electron scattering effects. In this study, we developed a thimble-like head bolus shield that surrounds the patient's entire head to prevent irradiation of the head during HBIe-. Materials and Methods: The feasibility of a thimble-like head bolus shield was evaluated using a simplified Geant4 Monte Carlo (MC) simulation. Subsequently, the head bolus was manufactured using a three-dimensional (3D) printed mold and Ecoflex 00-30 silicone. The fabricated head bolus was experimentally validated by measuring the dose to the Rando phantom using a metal-oxide-semiconductor field-effect transistor (MOSFET) detector with clinical configuration of HBIe-. Results and Discussion: The thimble-like head bolus reduced the electron fluence by 2% compared with that without a shield in the MC simulations. In addition, an improvement in fluence degradation outside the head shield was observed. In the experimental validation using the inhouse-developed bolus shield, this head bolus reduced the electron dose to approximately 2.5% of the prescribed dose. Conclusion: A thimble-like head bolus shield for the HBIe- technique was developed and validated in this study. This bolus effectively spares healthy skin without underdosage in the region of the target skin in HBIe-.

Neural network based numerical model updating and verification for a short span concrete culvert bridge by incorporating Monte Carlo simulations

  • Lin, S.T.K.;Lu, Y.;Alamdari, M.M.;Khoa, N.L.D.
    • Structural Engineering and Mechanics
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    • v.81 no.3
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    • pp.293-303
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    • 2022
  • As infrastructure ages and traffic load increases, serious public concerns have arisen for the well-being of bridges. The current health monitoring practice focuses on large-scale bridges rather than short span bridges. However, it is critical that more attention should be given to these behind-the-scene bridges. The relevant information about the construction methods and as-built properties are most likely missing. Additionally, since the condition of a bridge has unavoidably changed during service, due to weathering and deterioration, the material properties and boundary conditions would also have changed since its construction. Therefore, it is not appropriate to continue using the design values of the bridge parameters when undertaking any analysis to evaluate bridge performance. It is imperative to update the model, using finite element (FE) analysis to reflect the current structural condition. In this study, a FE model is established to simulate a concrete culvert bridge in New South Wales, Australia. That model, however, contains a number of parameter uncertainties that would compromise the accuracy of analytical results. The model is therefore updated with a neural network (NN) optimisation algorithm incorporating Monte Carlo (MC) simulation to minimise the uncertainties in parameters. The modal frequency and strain responses produced by the updated FE model are compared with the frequency and strain values on-site measured by sensors. The outcome indicates that the NN model updating incorporating MC simulation is a feasible and robust optimisation method for updating numerical models so as to minimise the difference between numerical models and their real-world counterparts.

Calculation of EHL Traction for a Model Hydrocarbon Using Molecular Simulation and Rheometry

  • Bair, Scott;McCabe, Clare;Cummings, Peter T.;Winer, Ward O.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.73-75
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    • 2002
  • Recently, remarkable agreement has been reported between nonequilibrium molecular dynamics simulation and high-pressure Couette rheometry on squalane. We utilized the parameters obtained from this unique collaboration along with high-pressure viscometer measurements to calculate the elastohydrodynamic traction curve. A comparison with measured traction at 1.29 GPa shows excellent agreement, confirming the validity of the measurements and simulations. It should no longer be necessary to invoke a different rheological response to explain film thickness and traction.

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Alignment estimation performance of Multiple Design Configuration Optimization for three optical systems

  • Oh, Eun-Song;Kim, Seong-Hui;Kim, Yun-Jong;Lee, Han-Shin;Kim, Sug-Whan
    • Bulletin of the Korean Space Science Society
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    • 2011.04a
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    • pp.31.1-31.1
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    • 2011
  • In this study, we investigated alignment state estimation performances of the three methods i.e. merit function regression (MFR), differential wavefront sampling (DWS) and Multiple Design Configuration Optimization (MDCO). The three target optical systems are 1) a two-mirror Cassegrain system for deep space Earth observation, 2) intermediate size three-mirror anastigmat for Earth ocean monitoring, and 3) extremely large segmented optical system for astronomical observation. We ran alignment state estimation simulation for several alignment perturbation cases including 1mm to 10mm in decenter and from 0.1 to 1 degree in tilt perturbation error for the two-mirror Cassegrain system. In general, we note that MDCO shows more competitive estimation performance than MFR and DWS. The computational concept, case definition and the simulation results are discussed with implications to future works.

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Robust optimization of a hybrid control system for wind-exposed tall buildings with uncertain mass distribution

  • Venanzi, Ilaria;Materazzi, Annibale Luigi
    • Smart Structures and Systems
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    • v.12 no.6
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    • pp.641-659
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    • 2013
  • In this paper is studied the influence of the uncertain mass distribution over the floors on the choice of the optimal parameters of a hybrid control system for tall buildings subjected to wind load. In particular, an optimization procedure is developed for the robust design of a hybrid control system that is based on an enhanced Monte Carlo simulation technique and the genetic algorithm. The large computational effort inherent in the use of a MC-based procedure is reduced by the employment of the Latin Hypercube Sampling. With reference to a tall building modeled as a multi degrees of freedom system, several numerical analyses are carried out varying the parameters influencing the floors' masses, like the coefficient of variation of the distribution and the correlation between the floors' masses. The procedure allows to obtain optimal designs of the control system that are robust with respect to the uncertainties on the distribution of the dead and live loads.

Monte-Carlo Simulation of Focused ton Beam Lithography (집속 이온빔 리소그라피의 몬데칼로 전산 모사)

  • 이현용;정홍배
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1993.11a
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    • pp.134-136
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    • 1993
  • Microelectronic fabrication technology .is based on the use of lithsgraphy to create small linewidths and patterns that make up ULSI. In previous papers, we discussed the theoretically calculated values such as ion range, ion concentration,ion transmission coefficient and the defocused ion beam-induced characteristics in a-Se$_{75}$Ge$_{25}$. In this paper, the typical Monte Carlo (MC) simulation results and p개cedures for the focused ion beam lithography were presented. The interaction and scattering of ions with the resist depend on the beam energy, impact parameter arid resist parameters. For ion exposure simulations, the quantity of interest is the spatial distribution of energy deposited by ions in the resist due to interaction phenomena with resist ions.s.s.

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Atomistic modeling for 3D dynamci simulation of ion implantation into crystalline silicon

  • 손명식;강정원;변기량;황호정
    • Proceedings of the IEEK Conference
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    • 1998.06a
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    • pp.421-424
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    • 1998
  • In this paper are presented a newly proposed 3D monte carlo (MC) damage model for the dynamic simulation in order to more accurately and consistently predict the implant-induced point defect distributions of the various ions in crystalline silicon. This model was applied to phosphorus implants for the ULSI CMOS technology developement. In additon, a newly applied 3D-trajectory split method has been implemented into our model to reduce the statistical fluctuations of the implanted impurity and the defect profiles in the relatively large implanted area as compared to 1D or 2D simulations. Also, an empirical electronic energy loss model is proposed for phosphorus and silicon implants. The 3D formations of the amorphous region and the ultra-shallow junction around the implanted region could be predicted by using our model, TRICSI(Transport ions into crystal-silicon).

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

  • Choi, Jae-Hyuck;Koo, Sung-Wan;Chung, Kyou-Il;Kim, Jin-Young
    • 한국정보통신설비학회:학술대회논문집
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    • 2009.08a
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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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A FRONTIER OF PARALLEL CFD: REAL-TIME IN-FLIGHT ICING SIMULATION OVER COMPLETE AIRCRAFT

  • Habashi, Wagdi G.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.1-1
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    • 2010
  • With the power of supercomputers increasing exponentially, there is an insatiable need for more advanced multi-disciplinary aerospace CFD simulations. A particular current interest is the 3D viscous turbulent simulation of the highly nonlinear aspects of aero-icing. The applications of CFD in that field are literally light-years behind aerodynamics, with a significant number of users still mired in correlations, or 2D, inviscid, incompressible, and, yes, Panel Methods simulations! Thus, the disparity of tools between aerodynamics and icing departments within an organization leads to a disconnect that makes ice protection a downstream isolated process that is not an integral part of the aerodynamic behavior of an aerospace system (aircraft, rotorcraft, jet engine, UAV, etc.). While 3D RANS has been recently introduced, it is still considered computationally too demanding for industry when wide parametric studies for certification are required. In addition, not unlike the situation in aerodynamics say 20 years ago, naysayers are at every corner claiming that CFD is not reliable and is of limited use.

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Probabilistic Integrity Assessment of CANDU Pressure Tube for the Consideration of Flaw Generation Time (결함발생 시점을 고려한 CANDU 압력관 결함의 확률론적 건전성평가)

  • Kwak, Sang-Log;Lee, Joon-Seong;Kim, Young-Jin;Park, Youn-Won
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.155-160
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    • 2001
  • This paper describes a probabilistic fracture mechanics (PFM) analysis based on Monte Carlo (MC) simulation. In the analysis of CANDU pressure tube, it is necessary to perform the PFM analyses based on statistical consideration of flaw generation time. A depth and an aspect ratio of initial semi-elliptical surface crack, a fracture toughness value, delayed hydride cracking (DHC) velocity, and flaw generation time are assumed to be probabilistic variables. In all the analyses, degradation of fracture toughness due to neutron irradiation is considered. Also, the failure criteria considered are plastic collapse, unstable fracture and crack penetration. For the crack growth by DHC, the failure probability was evaluated in due consideration of flaw generation time.

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