• 천문학회보
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• 제46권1호
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• pp.29.2-29.2
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• 2021

Intracluster light (ICL) is composed of the stars diffused throughout the galaxy cluster but does not bound to any galaxy. The ICL is a ubiquitous feature of galaxy clusters and occupies a significant fraction of the total stellar mass in the cluster. Therefore, the ICL components are believed to help understand the formation and evolution of the clusters. However, in the numerical study, one needs to perform the high-resolution cosmological hydrodynamic simulations, which require an expensive calculation, to trace these low-surface brightness structures (LSB). Here, we introduce the Galaxy Replacement Technique (GRT) that focuses on implementing the gravitational evolution of the diffused ICL structures without the expensive baryonic physics. The GRT reproduces the ICL structures by a multi-resolution cosmological N-body re-simulation using a full merger tree of the cluster from a low-resolution DM-only cosmological simulation and an abundance matching model. Using the GRT, we show the preliminary results about the evolution of the ICL in the on-going simulations for the various clusters.

• 센서학회지
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• 제27권3호
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• pp.150-155
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• 2018

Three different structures of GaN MOSFETs with trap distributions, trap levels, and densities were simulated, and its results were analyzed. Two of them are Schottky barrier MOSFETs(SB-MOSFETs): one with a p-type GaN body while the other is in the accumulation mode MOSFET with an undoped GaN body and regrown source/drain. The trap levels, distributions and densities were considered based on the measured or calculated properties. For the SB-MOSFET, the interface trap distribution affected the threshold voltage significantly, but had a relatively small influence on the subthreshold swing, while the bulk trap distribution affects the subthreshold swing more.

• 천문학회보
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• 제33권1호
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• pp.85.2-85.2
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• 2008

• 천문학회보
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• 제34권2호
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• pp.56.1-56.1
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• 2009

• 천문학회보
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• 제28권2호
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• pp.60-60
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• 2003

• 한국수자원학회논문집
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• 제48권12호
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• pp.1023-1035
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• 2015

본 연구에서는 해수-담수-해안대수층의 비선형 상호작용을 직접 해석할 있는 PBM(Porous Body Model) 기반의 3차원 N-S Solver인 LES-WASS-3D ver 2.0을 적용하며, 해안대수층의 해수침투모의를 수행하였다. 이와 같은 N-S Solver를 적용한 해안대수층의 해수침투모의는 국내 최초 수행되는 것일 뿐만 아니라, 국외적으로도 찾아보기 어려운 새로운 수치해석방법이라고 할 수 있다. 먼저 적용하는 수치모델을 검증하기 위하여 해안대수층의 해수-담수 경계면에 관한 수리모형실험결과와 비교 검토하여 수치모델의 타당성 및 유효성을 확인하였다. 그리고 해수위 및 지하수위 변화를 고려한 해안대수층 내의 해수침투모의를 수행하여 해수위-지하수위 차와 해수위의 비(${\Delta}h/h$)의 증가에 따른 해안대수층 내의 유동장 그리고 해수-담수 경계면 분포 특성에 관하여 논의하였다. 또한 기존의 비확산 수치모델에서 도출할 수 없었던, ${\Delta}h/h$에 따른 해안대수층 내의 연직 염분농도로 부터 해수침투 특성을 파악하였으며, 최종적으로 지표화 할 수 있는 ${\Delta}h/h$가 해안대수층 내의 해수침투거리에 미치는 영향에 대하여 분석하였다. 이 결과로부터 ${\Delta}h/h$가 작을수록 해안대수층 내의 해수침투가 약해지는 메커니즘을 이해할 수 있었다.

• 산업기술연구
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• 제20권A호
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• pp.229-238
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• 2000

Simulation analysis for an auto body manufacturing system has been performed in this study. The major goal is to figure out the condition yielding the production rate, 70 per hour. It is, however, very difficult to maintain this rate due to inherent system factors such as machine failure rates, machine repair rates, number of carriers between manufacturing lines(shops), carrier speed etc. We first carefully examined the system and developed a simulation model using ARENA. We then applied statistical experimental design concepts for performance analysis. Our results indicate that the buffer size of 30 and quick repair of failed robots are required for the desired production rate. Other factors, on the other hand, are seen to have minor effects on the throughput. The approach taken in this study and the results obtained may provide a practical guideline for performance analysis and thus be applied without trepidation for similar cases.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
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• pp.33-40
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• 1998

In recent domestic automotive industry, applications of computer simulation to the manufacturing of stamping dies for inner and outer body panels which greatly affect durability and aesthetic quality of automobiles, have been increased. Enhancement of die quality, and reduction of total die manufacturing time and consequently manufacturing cost are the visible outcome. However, to successfully apply the result of simulation by a commercial package to the die manufacturing, development of an optimal die manufacturing process is required upon the completion of analysis of forte and shortcomings of available sheet metal forming softwares in the market. Based on the results of numerical analysis of front door outer panel forming, this paper evaluates the applicability of simulation results to the real die making for automotive body panels. Also, it attempts to select an optimal die manufacturing process including design, machining and tryout. Lastly, it discusses the expected effects by adopting the selected process in a real stamping die manufacturing facility.

• 한국전자파학회논문지
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• 제24권11호
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• pp.1091-1097
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• 2013

이 논문은 $0.11{\mu}m$ RF CMOS 공정에서 비대칭 몸체 바이어싱을 적용한 비교기를 사용한 정류기를 제안한다. 제안하는 정류기는 MOSFET와 두 개의 비교기로 이루어져 있다. 이 비교기는 부하 전압이 입력 전압보다 높을 때 생기는 역방향 누설 전류를 줄이는 데 사용한다. 비대칭 몸체 바이어싱을 사용함으로써 비교기의 High에서 Low 상태로 바꾸는 기준 전압을 높이고, 누설 전류가 흐르는 시간을 줄인다. 13.56 MHz의 2 Vpp 교류전압을 입력하고, $1k{\Omega}$의 저항과 1 nF의 커패시터를 부하에 연결한 환경에서 측정하였다. 시뮬레이션 결과, 전압 변환 효율은 87.5 %, 전력 변환 효율은 45 %이고, 측정한 전압 변환 효율은 85.215 %, 전력 변환 효율은 50 %이다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
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• pp.110-120
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• 1998

Tailor-welded blanks are made of two or more different blanks in thickness or material. So car body with tailor-welded blanks need not reinforcement panels. However in order to make stamping tools for tailor-welded blanks, die engineers should know about the exact position of the welding line after the part is drawn. The necessity of knowledge about the position of welding line needs forming simulation methodology as a prior step in tooling. Therefor some parts of the simulation methodology are proposed and compared with the experimental results.