• Journal of Energy Engineering
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• v.7 no.1
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• pp.7-16
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• 1998

Numerical computations were performed for the gasification of five different coals such as Lewis-Stockton bituminous, Utah bituminous. Illinois #6 bituminous, Usibelli sub-bituminous and Beulah-Zap lignite, to assess the effect of variation in oxygen to coal ratio and steam to coal ratio on reactive flow fields within an axisymmetric, entrained-flow gasifier. The concentrations of major products, CO and $H_2$, were calculated with varying oxygen to coal ratio(0.7~1.4) and steam to coal ratio. To verify the validity of predictions, the predicted and the measured values of CO and $H_2$ concentrations at the exit of the gasifier were compared for Roto coal. Reasonable agreement was obtained between the predicted and measured values. Predictions showed that the (CO+H_2$) concentration increased gradually to its maximum value with increasing oxygen-coal ratio, and CO concentration decreased, but $H_2$ concentration increased to some extent with increasing steam-coal ratio. When the oxygen-coal ratio was between 1.0 and 1.2, and the steam-coal ratio was between 0.3 and 0.4, high values of the cold-gas efficiency were obtained.

• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.34-35
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.195-195
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• 2002

• 한국지구물리탐사학회:학술대회논문집
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• 2010.10a
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• pp.145-148
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• 2010

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4698-4706
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• 2014

In this study, the simulation was performed for the CO removal process using a composite membrane in DME production. The composite membrane, PEI-PDMS (polyetherimide- polydimethyl siloxane) manufactured by Airrane Co. Ltd., was used in the modeling through a commercial simulation design program, PRO/II with PROVISION 9.2 by Invensys. To simulate the process, the permeability constants of each of the pure component from Airrane Co. Ltd. were determined by regression analysis from the experimental data. The required separation membrane area and utility cost in the CO removal process were obtained using a chemical process simulator and composite membrane with a compatible permeability constant.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.375-378
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• 2009

본 논문에서는 API X80 강의 대변형 비선형 거동을 모사하기 위해 비선형 유한요소해석을 수행하였다. 고강도 강재의 거동을 모사하기 위해 GTN(Gurson-Tvergaad-Needleman) 모델을 사용하였으며, 비선형 해석을 위해 범용 유한요소해석 프로그램인 ABAQUS와 User Subroutine의 사용자 재료모델(UMAT)을 연계하여 사용하였다. 해석결과와 인장실험의 결과와의 비교를 통해 GTN 모델에서 사용되는 재료모델 상수를 도출하였고, 도출된 값들은 개발된 사용자 재료모델과 함께 API X80 강의 각종 실험을 모사하고 대변형 상황의 강재 파이프의 거동을 분석하는데 유용하게 사용될 수 있다.

• Progress in Medical Physics
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• v.20 no.4
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• pp.225-234
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• 2009

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level $\alpha=0.05$ set.

• Progress in Medical Physics
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• v.22 no.2
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• pp.79-84
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• 2011

In this study, Geant4 based Monte Carlo simulations were carried out for medical linear accelerator. Modified Medical Linac2 toolkit was used for calculation. The energy spectrum, most probable energy and the photon mean energy compared with the published results using the EGS4 code. The results well agreed with published results. The calculated results of photon fluence, energy fluence and mean energy according to the radius from the centre of the beam were analyzed. Monte Carlo simulation using Medical Linac2 code is considered to be useful for analysis of medical linear accelerator. Because the calculated results varies depending on Physics List model for same head structure. It it important to choose the right model for research purpose. Monte Carlo simulation using GEANT4 Medical Linac2 is a valuable for any novice to adopt this code to the study related to 6 MV photon fluence from medical linear accelerator.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.279-284
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• 2021

In this study, the performance and distribution of fluid concentration, pressure, and current density of a proton exchange membrane fuel cell was investigated. In this paper, the two different types of flow field design were compared, singel channel and 5-channels. As a result, the 5-channels of flow field showed the better performance than that of single chanel. Especially, the single channel showed better performance in terms of mass transfer loss area.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.564-564
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• 2013

홀 추력기는 플라즈마를 이용하는 전기추력기 중 하나로, 인공위성의 자세제어, 궤도수정, 궤도천이 뿐만아니라 행성간 임무수행을 위한 우주선의 엔진으로 사용된다. 홀 추력기 채널 내부에 발생된 Xe 이온들은 양극과 음극 사이에 존재하는 전기장에 의해 가속되어 추력을 발생시킨다. 이때 Xe 이온들은 자기장에 의해 감금된 전자와 중성 Xe 원자 사이의 충돌에 의해 발생하며, 실험적 및 이론적 연구를 통해 단일 전하를 띤 이온(Xe II)뿐만 아니라 다중 전하(Xe III 등)를 띤 이온도 생성되는 것으로 알려져 있다. 이온의 전하량 비율은 홀 추력기의 추력효율 및 연료효율에 영향을 미치며, 다중 전하를 띤 이온의 높은 에너지는 채널벽의 침식문제를 야기하는 등 홀 추력기 이온빔의 전하량 분석 연구는 물리적 연구측면 뿐만아니라 실용적인 측면에서도 매우 중요하다. 본 연구에서는 자기장과 그에 수직한 방향의 전기장에서 발생하는 로렌츠 힘을 이용하여 이온의 전하량을 분석할 수 있는 $E{\times}B$ 탐침을 설계 및 개발하였다. 개발된 $E{\times}B$ 탐침은 70 mm 길이의 집속기와 $148{\times}138{\times}90mm$의 본체, 40 mm길이의 콜렉터로 구성된다. $E{\times}B$ 탐침 설계에 가장 중요한 균일한 자기장 설계를 위해 전산모사를 통해 최적화 작업을 진행하였으며, 실험을 위한 진단계의 최적화와 초기 실험결과가 발표될 예정이다.