• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1131-1141
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• 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.

• Journal of the Chungcheong Mathematical Society
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• v.8 no.1
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• pp.55-69
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• 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.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.1-13
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• 2009

The influence of moving rainstorms to runoff was analysed for the nonsymmetric shaped basins using kinematic wave theory. The distribution types of moving rainstorms are uniform, advanced, delayed and intermediate type, the nonsymmetric shaped basins are square, oblong and elongated shape. The runoff hydrographs were simulated and the characteristics were compared with the symmetric shaped basins for the rainstorms moving up, down and cross the basins with various velocities. The smallest differences of peak runoff of symmetric and nonsymmetric basins are appeared in the case of elongated basin, and the largest differences are shown at the oblong basin for the downstream direction. The identical results are shown for the upstream direction. The greatest peak runoff differences are shown in the delayed type rainstorm and the smallest differences are in the advanced type rainstorm for the crossstream direction. The oblong shaped basin generates the longest peak time and shortest peak time for the elongated shape basin.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.117-120
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• 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.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.536-543
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• 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.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.435-442
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• 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.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.906-915
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• 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.

• Communications of the Korean Mathematical Society
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• v.12 no.1
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• pp.145-155
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• 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
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• v.16 no.1
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• pp.1-13
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• 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.

• Journal of Korean Society of Steel Construction
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• v.14 no.3
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• pp.423-432
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• 2002

This study presented analytical and numerical solutions for spatial free vibration of nonsymmetric thin-walled circular curved beams. The closed-form solutions were obtained for in-plane free vibration analylsis of monosymmetric curved beams. Likewise, two types of thin-walled curved beam elements were developed using the third and the fifth order Hermitian polynomials. In order to illustrate the accuracy and usefulness of the present method, this study presented analytical and numerical solution and compared these with the results using the ABAQUS's shell elements. In particular, effects of the thickness-curvature as well as the inextensional condition were investigated on the free vibration of curved beams with nonsymmetric sections.