• Journal of applied mathematics & informatics
• /
• 제28권5_6호
• /
• pp.1131-1141
• /
• 2010

We develop an algorithm for computing a sparse approximate inverse for a nonsymmetric positive definite matrix based upon the FFAPINV algorithm. The sparse approximate inverse is computed in the factored form and used to work with some Krylov subspace methods. The preconditioner is breakdown free and, when used in conjunction with Krylov-subspace-based iterative solvers such as the GMRES algorithm, results in reliable solvers. Some numerical experiments are given to show the efficiency of the preconditioner.

• 충청수학회지
• /
• 제8권1호
• /
• pp.55-69
• /
• 1995

This paper proposes two variants of BCG-like method for solving nonsymmetric linear sytems. It is shown that these new algorithms converge faster and more smoothly than the existing BCG and BiCGSTAB algorithms for problems tested in this paper.

• 한국습지학회지
• /
• 제11권1호
• /
• pp.1-13
• /
• 2009

비대칭형상의 유역에서 이동강우로 인한 유출영향을 운동파이론을 적용하여 분석하였다. 이동강우 분포형은 균등분포형, 전진형, 지연형 및 중앙집중형을 사용하였고, 비대칭유역형상은 정사각형, 신장형, 및 장방형유역에 대하여 분석하였다. 다양한 이동속도를 가진 이동강우가 비대칭유역의 상류, 하류 및 횡방향으로 이동할 때 유출수문곡선을 모의하여 그 특성을 대칭유역과 비교분석하였다. 하류방향에 대하여 신장형유역에서 대칭과 비대칭유역의 첨두유량 차이가 가장 작은 반면에 장방형유역에서 가장 큰 차이를 보여주고 있으며, 이것은 상류방향에서도 동일하게 나타났다. 횡방향에서는 대칭, 좌비대칭 및 우비대칭유역 모두 지연형 강우에서 가장 큰 첨두유량을 그리고 전진형강우에서 가장 작은 첨두유량을 보이고 있다. 첨두시간은 장방형유역에서 가장 길게 나타나고 신장형유역에서 가장 짧게 나타났다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.117-120
• /
• 2001

In hot roiling process, new rolling mills have been apapted to strip rolling but we can usually experience the problem of snaking of strip. This phenomenon was arisen by nonsymmetric rolling and on-centering and cambering of a strip and other mill conditions. Three dimensional analysis for strip rolling predicted the influence of nonsymmetric rolling, off-centering and pair crossing system This study evaluated the fundamental characteristics of snaking of a strip to optimize the operating condition for trouble free rolling.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 춘계학술대회 논문집
• /
• pp.536-543
• /
• 2005

Derivation procedures of exact dynamic stiffness matrices of thin-walled curved beams subjected to axial forces are rigorously presented for the spatial free vibration analysis. An exact dynamic stiffness matrix is established from governing equations for a uniform curved beam element with nonsymmetric thin-walled cross section. Firstly this numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. Thus, displacement functions of dispalcement parameters are exactly derived and finally exact stiffness matrices are determined using element force-displacement relationships. The natural frequencies of the nonsymmetric thin-walled curved beam are evaluated and compared with analytical solutions or results by ABAQUS's shell elements in order to demonstrate the validity of this study.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
• /
• pp.435-442
• /
• 2001

Derivation procedures of exact dynamic element stiffness matrix of shear deformable nonsymmetric thin-walled straight beams are rigorously presented for the spatial free vibration analysis. An exact dynamic element stiffness matrix is established from governing equations for a uniform beam element with nonsymmetric thin-walled cross section. First this numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. Thus, the displacement functions of dispalcement parameters are exactly derived and finally exact stiffness matrices are determined using member force-displacement relationships. The natural frequencies are evaluated and compared with analytic solutions or results of the analysis using ABAQUS' shell elements for the thin-walled straight beam structure in order to demonstrate the validity of this study.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.906-915
• /
• 2004

Derivation procedures of exact dynamic stiffness matrices of thin-walled curved beams subjected to axial forces are rigorously presented for the spatial free vibration analysis. An exact dynamic stiffness matrix is established from governing equations for a uniform curved beam element with nonsymmetric thin-walled cross section. Firstly this numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. Thus, displacement functions of dispalcement parameters are exactly derived and finally exact stiffness matrices are determined using clement force-displacement relationships. The natural frequencies of the nonsymmetric thin-walled curved beam are evaluated and compared with analytical solutions or results by ABAQUS's shell elements in order to demonstrate the validity of this study.

• 대한수학회논문집
• /
• 제12권1호
• /
• pp.145-155
• /
• 1997

We present a couple of tools that can be used in the solution of nonsymmetric eigenvalue problems. The first one allows us to convert power iterates into Arnoldi's results so that a few eigenpairs are easily obtainable. The other converts Arnoldi's results into power iterates to simulate the power method and improve the result. Suggestions for application are also given.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제16권1호
• /
• pp.1-13
• /
• 2012

In this paper we present an a posteriori error estimator for the stabilized P1 nonconforming finite element method of the linear elasticity problem based on a nonsymmetric H(div)-conforming approximation of the stress tensor in the first-order Raviart-Thomas space. By combining the equilibrated residual method and the hypercircle method, it is shown that the error estimator gives a fully computable upper bound on the actual error. Numerical results are provided to confirm the theory and illustrate the effectiveness of our error estimator.

• 한국강구조학회 논문집
• /
• 제14권3호
• /
• pp.423-432
• /
• 2002

비대칭 박벽단면을 갖는 곡선보의 자유진동해석을 수행할 수 있는 엄밀해 및 유한요소 이론을 제시한다. 단순지지된 일축대칭 박벽단면을 갖는 곡선보의 면내 자유진동 모드에 대응하는 엄밀해를 산정하였으며, 곡섬보를 유한요소로 분할하여 요소의 변위장을 요소의 변위벡터의 대하여 축방향 신장조건에서는 3차 그리고 비신장조건에서는 5차의 Hermitian 다항식으로 나타내고, 이를 운동방정식에 대입함으로써 탄성강성행렬과 질량행렬을 유도한다. 또한 본 연구에서 얻어진 엄밀해와 곡선보요소를 이용한 유한요소 해석결과를 ABAQUS 쉘요소를 이용하여 얻어진 결과와 비교 검토함으로써 본 연구의 타당성을 입증한다. 특히 곡선보의 축방향 비신장조건과 두께-곡률효과가 동적거동에 미치는 영향을 조사한다.