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다중스케일 모델링을 이용한 나노임프린트 리소그라피 전산모사
권성진(Sungjin Kwon),강지원(Jeewon Kang),김성엽(Sung Youb Kim),이윤섭(Yoon Sup Lee),엄윤용(Y.Y. Earmme),임세영(Seyoung Im) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Nano-Imprint Lithography(NIL) is a patterning technique at nano-size in limelight of requesting to reduce thespace between patterns. NIL is modeled under systematic multiscale consideration for a coarse grained molecular dynamics model. Force fields of a united atom model and a bead-spring model for the resin materials, obtained from fitting with the quantum mechanical solution, are employed for computation. The initial configuration of the polymer resin for UV nano imprinting is obtained from Monte Carlo simulation and the initial relaxation procedure. To simulate NIL process, we employ the Nose-Poincare thermostat for temperature controlled Molecular Dynamics (MD), which exhibits enhanced numerical stability even when the temperature fluctuation is large in the case of small number of particles system. Various aspects of NIL process from the mechanics view are discussed based on the numerical solution from the present multiscale modeling.
권성진(Sungjin Kwon),이영민(Youngmin Lee),임세영(Seyoung Im) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
To find out meaningful quantitive and qualatative properties of materials, we tend to look into an increasingly the large scale problems in molecular dynamics (MD) simulation by using parallel computing algorithm. We examine the speed-up rate according to load balancing, and the performance evaluation of parallel MD simulation schemes such as OpenMP, shared data method, force decomposition method, the complete distribution method based on domain decomposition. The simulation is performed for a nano-indentation of an Al thin film with EAM potential. The result shows that the complete distribution method based on domain decomposition is more efficient than other methods in aspect to speed-up and memory saving.
텅스텐 모노블락을 적용한 한국형 핵융합 실증로 디버터의 열수력적 최적 설계
권성진(Sungjin Kwon),임기학(Kihak Im),박종성(Jong Sung Park) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A conceptual design study of the Korean fusion demonstration reactor (K-DEMO) has been carried out since 2012 as following the Korean fusion development roadmap based on the Fusion Energy Development Promotion Law (FEDPL) legislated in 2007. The present in-vessel components of the K-DEMO have been studied for the 2,200 MW of fusion power. Almost half of the plasma power should be cooled down in the divertor. Especially, 10 MW/m² of the peak heat flux locally concentrates on the narrow section of the divertor target. To faithfully cool down the heat load, the selection of materials that the divertor is important as well as the decision of design parameters. Especially, the choice and design of the heat sink material in the divertor target are quite significant because the heat sink directly interfaced with the coolant. Reduced activation ferritic martensitic (RAFM) steel and CuCrZr have been considered the most promising candidates as the heat sink material. The preliminary designs of the high heat flux (HHF) units operating within materials’ own allowable temperature were derived by accomplishing thermohydraulic analyses for RAFM and CuCrZr. Based on the designs of HHF units with a support structure.
권성진(Sungjin Kwon),김경환(Gyeonghwan Kim) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.1
차량을 포함하는 임의의 영상에서 번호판 추출은 다양한 조명조건 및 배경, 촬영 각도, 번호판 종류 등의 요인으로 인해 고도의 영상처리 과정을 필요로 한다. 본 논문에서는 실제 환경에서 발생할 수 있는 이러한 요인들에 대해 강건한 번호판 추출 방법을 제안한다. 제안하는 방법은 입력영상의 RGB 성분들을 색상성분과 명암성분으로 분리할 수 있는 칼라모델 HSI로 변환하고, H(hue)와 S(saturation)성분을 이용하여 번호판의 배경색상을 고려한 칼라 퍼지지도를 구성한다. 또한, I(intensity)성분을 이용하여 에지밀도를 추출하고, 에지밀도지도에 기반한 영역분리 퍼지지도를 생성한다. 마지막으로, 후보영역 탐색을 위해 칼라 퍼지지도와 영역분리 퍼지지도를 결합하고, 연결성분 해석(Connected Component Analysis)을 통해 ROI(Region Of Interest)를 추출한다. 제안하는 방법의 유효성 검증을 위해 조명 및 촬영 각도에 제한을 거의 두지 않고 촬영된 차량 영상 410장을 실험 영상으로 사용하였다. 실험 결과에서는 97.1%의 효과적인 추출 성공률을 볼 수 있었다.
권성진(Sungjin Kwon),박종연(Jong Youn Park),이영민(Youngmin Lee),김성엽(Sung Youb Kim),임세영(Seyoung Im) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
To calculate atomic-level stress, we choose the stress formulation proposed by Shengpin Shen and S.N. Atluri. The formulation based on the SPH(Smoothed Particle Hydrodynamics) method does not need atomic volume. The formulation is not only robust, accurate, and easy to implement, but also appropriate for both homogeneous and inhomogeneous deformation. We illustrate various numerical examples of molecular dynamics simulation.
온도 제어 비평형 분자동역학 방법을 이용한 나노임프린트 리소그라피 공정의 전산모사
권성진(Sungjin Kwon),이영민(Youngmin Lee),임세영(Seyoung Im) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Temperature is an essential process variable in nanoimprint lithography(NIL) where the temperature varies between room temperature and above the glass transition temperature. To simulate NIL process, we employ both the Nose-Poincare method for temperature controlled molecular dynamics(MD) and force field for polymer material i.e. polymethyl methacrylate(PMMA), which is most widely selected as NIL resist. Nose-Poincare method, which convinces the conservation of Hamiltonian structure and time-reversal symmetry, overcomes the drawbacks inherent in the conventional methods such as Nose thermostat and Nose-Hoover thermostat. Thus, this method exhibits enhanced numerical stability even when the temperature fluctuation is large. To describe PMMA, we adopt the force field which account for bond stretch, bending, torsion, inversion, partial charge, and van der Waals energy.
순환다중 thermostat 에 의한 (NσT) 앙상블의 분자 동역학 계산
권성진(Sungjin Kwon),이영민(Youngmin Lee),임세영(Seyoung Im) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
This is the first stage of our multistage study, of which the ultimate goal is the completion of a multiscale computing strategy for nano imprinting lithography. The first stage focuses on computational implementation of MD (Molecular Dynamics) simulation for (NσT) ensembles. The so-called RMT (Recursive Multiple Thermostats) formulation is employed for an efficient and accurate simulation of thermodynamic systems, and we demonstrate that the scheme is extremely useful for calculating some equilibrium properties of solids in an effective manner. The advantage of the scheme over Nose-Hoover Chain method is discussed in terms of computational efficiency and solution stability.
김찬중(Chanjung Kim),권성진(Sungjin Kwon),이봉현(Bonghyun Lee),박현만(Hyunman Park),성기득(Kideug Sung),조춘택(Chuntaek Cho) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
The nature of acoustic radiation is responsible for tire vendors as one of promising performances directly related to the driver's comfortability in a vehicle system and thereby, the accurate prediction of the acoustic radiation is required during the development of tire system. Even though the prediction technology of acoustic radiation itself is reliable using proven softwares, the prediction of a tire system under developing process is hard to guarantee since the dynamic interaction between the tire and suspension module could not be considered sufficiently owing to the suspension module is not constructed as a mature model. In this paper, the dynamic effect of a suspension module over a tire system is investigated to verify that the quarter-car model can provide the more accurate acoustic prediction than that case of tire model alone. The acoustic radiation analysis is performed for two finite element models of the tire system, with and without a suspension model, using a wheel force transducer data on a proving ground. The characteristics of acoustic result according to the special events of proving ground is addressed at physical perspectives and it concludes that the reliable prediction of a tire system can be expected only in case the dynamics of suspension module is included.