• 지질공학
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• 제5권2호
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• pp.155-165
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• 1995

열극암반내의 지하수유동 및 용질이동 해석을 위해서는 추계론적인(Simulation Techique) 3차원 불연속체 모형(Discrete Fracture Model)이 요구된다. Monte Carlo 모의기법(Simulation Techique)에 의해 구성된 추계론적 불연속체모형을 지하 유류저장공동의 기밀성평가를 위한 지하수유동 및 용질이동 모의에 적용하였다. 불연속체모형구성에 영향을 미치는 열극 특성요소는 방향서 및 크기로 분석되었으며, 구성도니 모형(Model)에서의 지하수유동에 영향을 미치는 요소는 투수성 열극밀도로 분석되었다. Particle Tracking 기법을 사용한 불연속체모형의 용질이동 모의에서는 열극의 투수성에 의해 이동경로 및 이동속도에 많은 차이가 관찰되었다. 검증된 추계론적 불연속체모형은 지하 유류저장공동 기밀성평가에 적용이 가능함이 부분적으로 인정되었다.

• Journal of Radiation Protection and Research
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• 제48권4호
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• pp.204-212
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• 2023

Background: Isotopes of the projectile may be produced along the beam path during the irradiation of a target by a heavy ion due to inelastic interactions with the media. This study analyzed the production cross-section of carbon (C) and Helium (He) projectile's isotopes resulting from the interactions of these beams with different materials along the beam path. Materials and Methods: In this study, we transport C and He ion beams through different materials. This transportation was made by the Monte Carlo simulation. Particle and Heavy Ion Transport code System (PHITS) has been used for this calculation. Results and Discussion: It has been found that ¹⁰C, ¹¹C, and ¹³C from the ¹²C ion beam and ³He from the ⁴He ion beam are significant projectile's isotopes that have higher flux than other isotopes of these projectiles. The ⁴He ion beam has a higher projectile's isotope production cross-section along the beam path, which adds more impurities to the beam than the ¹²C ion beam. These projectile's isotopes from both the ¹²C and ⁴He ion beams have higher production cross-sections in hydrogenous materials like water or polyethylene. Conclusion: It is important to distinguish these projectile's isotopes from the primary beam particles to obtain a precise and accurate cross-section result by minimizing the error during measurement with a nuclear track detector. This study will show the trend of the production probability of projectile's isotopes for these ion beams.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2404-2411
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• 2024

The GEOUNED code is specifically designed to convert CAD models, defined using the B-rep approach, into MC radiation transport models, defined using the CSG approach, and vice versa from MC to CAD. This code incorporates standard features commonly found in conversion tools, including decomposition, conversion, and automatic void generation. Additionally, it introduces innovative features, mainly in the automatic void generation part, which are described in this article. GEOUNED has demonstrated successful application in highly detailed 3D models used in fusion neutronics, which are known for their complex geometries, particularly those utilized in ITER. The article includes examples showcasing GEOUNED's performance in these challenging models, as well as custom applications that highlight its flexibility in addressing non-standard problems. The code is open-source and utilizes Open CASCADE as the geometry engine, with FreeCAD serving as the Python API.

• 대한기계학회논문집B
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• 제31권4호
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• pp.320-329
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• 2007

Electrokinesis and dielectrophoresis are important transport phenomena produced by external electric field applied to a microchannel containing a conductive fluid. We developed a CFD code to predict electrokinetic and dielectrophoretic flows in a microchannel with a uniform circular post array. Using the code, we calculated particle velocities driven by electrokinesis and dielectrophoresis, and conducted Monte Carlo simulations to visualize the particle motions. The code was validated by comparing the results with those from previous studies in literature. At a low electric field, electrokinesis and diffusion is the dominant transport mechanism. At a moderate electric field, dielectrophoresis is balanced with electrokinesis and diffusion, resulting in flowing filaments of particles in the microchannels. However, dielectrophoresis overwhelms the flow at a high electric field and traps particles locally. These results provide useful insight for optimizing design parameters of a microfluidic chip for biochemical analysis, especially for development of on-chip sample pretreatment techniques using electrokinetic and dielectrophoretic effects.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.557-560
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• 2008

A two-dimensional particle-in-cell(PIC) simulation with a Monte-Carlo Collision(MCC) has been developed to investigate the discharge characteristics of the acceleration channel of a HET. The dynamics of electrons and ions are treated with PIC method at the time scale of electrons in order to investigate the particle transport. The densities of charged particles are coupled with Poisson's equation. Xenon neutrals are injected from the anode and experience elastic, excitation, and ionization collisions with electrons, and are scattered by ions. These collisions are simulated by using an MCC model. The effects of control parameters such as magnetic field profile, electron current density, and the applied voltage have been investigated. The secondary electron emission on the dielectric surface is also considered.

• 대한방사선기술학회지:방사선기술과학
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• 제47권3호
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• pp.213-218
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• 2024

The myocardial nuclear medicine examination is widely performed to diagnose myocardium disease using various radionuclides. Although image quality according to radionuclides has improved, the radiation exposure for target organ as well as peripheral organs should be considered. Here, the aim of this study was to evaluate absorbed dose (Gy) for peripheral organs in myocardial nuclear medicine scan from myocardium according to various scan environments based on Monte Carlo simulation. The simulation environment was modeled 5 cases, which were considered by radionuclides, number of injections, and radiodosage. In addition, the each radionuclide simulation such as distribution fraction was considered by recommended standard protocol, and the mesh computational female phantom, which is provided by International Commission on Radiological Protection (ICRP) 145, was used using the particle and heavy ion transport code system (PHITS) version 3.33. Based on the results, the closer to the myocardium, the higher the absorbed dose values. In addition, application for dual injection for radionuclides leaded to high absorbed dose compared with single injection for radionuclide. Consequently, there is difference for absorbed dose according to radionuclides, number of injections, and radiodosage. To detect the accurate diseased area, acquisition for improved image quality is crucial process by injecting radionuclides, however, we need to consider absorbed dose both target and peripheral inner organs from radionuclides in terms radiation protection for patient.

• 한국방사선학회논문지
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• 제16권5호
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• pp.527-536
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• 2022

본 연구는 우주방사선 차폐물질 설계를 위한 선행연구 차원에서 우주방사선에 대한 물질별 방사선 차폐특성을 분석하였다. 특히 EMP 및 방사선 차폐에 효과가 있다고 알려진 경량 연자성 복합소재에 대한 우주방사선 차폐물질 활용 가능성을 확인하고자 하였다. 이를 위해 Monte Carlo N-Particle(MCNP) 모델링 기법과 열중성자 차폐실험을 수행하였으며, MCNP의 우주방사선 모델인 Skymap.dat를 활용하였다. 연구결과 폴리에틸렌, 붕소폴리에틸렌, 탄소나노튜브 등 탄소와 수소를 함유한 물질의 경우 증발 중성자 에너지 영역 대 이하의 중성자 감소에 효과적인 것으로 나타났으며 SS316, 경량 연자성 물질 등 철을 함유한 물질은 캐스케이드 중성자 차폐성능이 뛰어난 것을 확인할 수 있었다. 특히 경량 연자성 물질의 경우 붕소를 함유하고 있어 저속중성자 영역의 중성자 감소에도 효과적인 것으로 나타났으며, 향후 탄소 및 수소 등 탄성산란 물질을 보강한다면 우주방사선 중성자 전 영역에서 유의미한 차폐효과를 보여줄 것으로 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1932-1934
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• 1996

Electron transport coefficients are calculated in nitrogen over the E/p range $50{\sim}700\;V\;cm^{-1}$ $Torr^{-1}$ by a Monte Carlo method, using a set of electron collision cross sections measured by authors.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1339-1348
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• 2018

The aim of this paper is to determine neutronic performances of the light water reactor (LWR) spent fuel mixed with fertile thorium fuel in a FFHR. Time dependent three dimensional calculations for major technical data, such as blanket energy multiplication, tritium breeding ratio, cumulative fissile fuel enrichment and burnup have been performed by using Monte Carlo Neutron-Particle Transport code MCNP5 1.4, coupled with a novel interface code MCNPAS, which is developed by our research group. A self-sustaining tritium breeding ratio (TBR>1.05) has been kept throughout the calculations. The study has shown that the fissile fuel quality will be improved in the course of the transmutation of the LWR spent in the FFHR. The latter has gained the reusable fuel enrichment level conventional LWRs between one and two years. Furthermore, LWR spent fuel - thorium mixture provides higher burn-up values than in light water reactors.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1210-1217
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• 2023

The assessment of radiation fields in the lithium loop pipes and dump tank during the operation were performed for International Fusion Materials Irradiation Facility - DEMO-Oriented NEutron Source (IFMIF-DONES) in order to obtain the radiation dose-rate maps in the component surroundings. Variance reduction techniques such as weight window mesh (produced with the ADVANTG code) were applied to bring the statistical uncertainty down to a reasonable level. The biological dose was given in the study, and potential shielding optimization is suggested and more thoroughly evaluated. The MCNP Monte Carlo was used to simulate a gamma particle transport for radiation shielding purposes for the current Li Systems' design. In addition, the shielding efficiency was identified for the Impurity Control System components and the dump tank. The analysis reported in this paper takes into account the radiation decay source from and activated corrosion products (ACPs), which is created by d-Li interaction. As a consequence, the radiation (resulting from ACPs and Be-7) shielding calculations have been carried out for safety considerations.