• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.147.1-147.1
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• 2005

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.778-789
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• 2017

This paper presents an improved subdomain method to predict the magnet field distributions and electromagnetic performance of the surface-mounted permanent magnet (SPM) machines with static or dynamic eccentricity. Conventional subdomain models are either based on the scalar magnet potential to predict the rotor eccentricity effect or dependent on the magnetic vector potential without considering the eccentric rotor. In this paper, both the magnetic vector potential and the perturbation theory are introduced in order to accurately calculate the effect of rotor eccentricity on the open-circuit and armature reaction performance. The calculation results are presented and validated by the corresponding finite-element method (FEM) results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.83-90
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• 2004

Substructuring methods are usually used in finite element structural analyses. In this study a multi-level substructuring algorithm is developed and proposed as a possible candidate for incompressible fluid solves. Finite element formulation for incompressible flow has been stabilized by a modified residual procedure proposed by Ilinca et.al.[5]. The present algorithm consists of four stages such as a gathering stage, a condensing stage, a solving stage and a scattering stage. At each level, a predetermined number of elements are gathered and condensed to form an element of higher level. At highest level, each subdomain consists of only one super-element. Thus, the inversion process of a stiffness matrix associated with internal degrees of freedom of each subdomain has been replaced by a sequential static condensation. The global algebraic system arising feom the assembly of each subdomains is solved using Conjugate Gradient Squared(CGS) method. In this case, pre-conditioning techniques usually accompanied by iterative solvers are not needed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.625-628
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• 1995

A static/implicit finite element code for sheet forming (ITAS3D) is parallelized on IBM SP 6000 multi-processor computer. Computing-load-balanced domain decomposition method and the direct solution method at each subdomain (and interface) equation are developed. The system of equations for each subdomain are constructed by condensation and calculated on each processor. Approximated operation counts are calculated to set up the nonlinear equation system for balancing the compute load on each subdomain. Th esquare cup tests with several numbers of elements are used in demonstrating the performance of this parallel implementation. This procedure are proved to be efficient for moderate number of processors, especially for large number of elements.

• 대한수학회보
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• 제53권3호
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• pp.853-874
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• 2016

Based on a particular overlapping domain decomposition technique, a parallel finite element discretization algorithm for the generalized Stokes equations is proposed and investigated. In this algorithm, each processor computes a local approximate solution in its own subdomain by solving a global problem on a mesh that is fine around its own subdomain and coarse elsewhere, and hence avoids communication with other processors in the process of computations. This algorithm has low communication complexity. It only requires the application of an existing sequential solver on the global meshes associated with each subdomain, and hence can reuse existing sequential software. Numerical results are given to demonstrate the effectiveness of the parallel algorithm.

• 대한기계학회논문집A
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• 제30권6호
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• pp.705-712
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• 2006

A finite element method based on the penalized subdomain-interface framework is proposed for fully-coupled, nonlinear thermomechanical analyses with thermal contact anuor radiation boundaries. In the variational formulation, a well-known penalty functional scheme is adopted for connecting subdomains and interfaces that satisfy various continuity requirements. As a logical consequence, the whole domain can be arbitrarily divided into independently-modeled subdomains without considering the conformity of meshes along their interfaces. Since the nonlinearities due to the contact and radiation boundaries can be localized within a few subdomains, the computational efficiency of the present method is greatly increased with appropriate solution algorithms. By solving some numerical problems, these advantageous features are confirmed carefully.

• 충청수학회지
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• 제22권2호
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• pp.211-216
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• 2009

Let G be a Denjoy domain and let G' a Denjoy proper subdomain of G and homeomorphic to G. We consider conformal re-imbeddings of G' into G. Let G and G' are N-connected. We know that if N = 2, there is a re-imbedding f of G' into G such that G - cl(f(G')) has an interior point. In this note, we obtain the following theorem. If $N{\geq}3$, G has a Denjoy proper subdomain G' such that, for any re-imbeddings f of G' into G, G - cl(f(G') has no interior point.

• Molecules and Cells
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• 제38권9호
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• pp.789-795
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• 2015

A chromosome territory is composed of chromosomal subdomains. The internal structure of chromosomal subdomains provides a structural framework for many genomic activities such as replication and DNA repair, and thus is key to determining the basis of their mechanisms. However, the internal structure and regulating proteins of a chromosomal subdomain remains elusive. Previously, we showed that the chromosome territory expanded after BAF53 knockdown. Because the integrity of chromosomal subdomains is a deciding factor of the volume of a chromosome territory, we examined here the effect of BAF53 knockdown on chromosomal subdomains. We found that BAF53 knockdown led to the disintegration of histone H2B-GFP-visualized chromosomal subdomains and BrdU-labeled replication foci. In addition, the size of DNA loops measured by the maximum fluorescent halo technique increased and became irregular after BAF53 knockdown, indicating DNA loops were released from the residual nuclear structure. These data can be accounted for by the model that BAF53 is prerequisite for maintaining the structural integrity of chromosomal subdomains.

• 한국항공우주학회지
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• 제33권11호
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• pp.7-14
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• 2005

접촉 현상을 포함하는 완전 연계된 열기계학적 문제에 대한 정확하고 효율적인 해석을 위하여 부영역과 공유면에 근거한 유한요소 정식화 기법을 제안하였다. 부영역과 공유면을 결합하기 위한 등식 적합 조건을 벌칙 함수로 처리함으로써 모든 유효 강성 행렬이 양정치화되며, 역행렬과 같은 각종 수치 연산이 매우 간편하다. 또한 전체 구조 형상이 복잡하더라도 대상 영역을 임의의 부영역으로 분할한 후, 공유면에서의 절점 연속성 등을 고려하지 않고 각 부영역을 독립적으로 유한요소 모델링할 수 있다. 컴퓨터 코드의 개발 및 수치 예제의 해석을 통하여 본 기법에 대한 기본적인 특성을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.15-25
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• 2004

This paper outlines a new convergence acceleration de-signed to solve scramjet flowfields with zones of re-circulation. Named the “marching-window”, the algorithm consists of performing pseudo-time iterations on a minimal width subdomain composed of a sequence of cross-stream planes of nodes. The upstream boundary of the subdomain is positioned such that all nodes upstream exhibit a residual smaller than the user-specified convergence threshold. The advancement of the downstream boundary follows the advancement of the upstream boundary, except in zones of significant streamwise ellipticity where a streamwise ellipticity sensor ensures its continuous progress. Compared to the standard pseudo-time marching approach, the march-ing-window is here seen to decrease the work required for convergence by up to 24 times for supersonic flows with little streamwise ellipticity and by up to 8 times for supersonic flows with large streamwise separated regions. The memory requirements are observed to be reduced sixfold by not allocating memory to the nodes not included in the computational subdomain. The marching-window satisfies the same convergence criterion as the standard pseudo-time stepping methods, hence resulting in the same converged solution within the tolerance of the user-specified convergence threshold. The extension of the marching-window to the weakly-ionized Navier-Stokes equations is also discussed.