• 한국콘텐츠학회논문지
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• 제5권4호
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• pp.204-211
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• 2005

본 논문은 비균일 단일루프의 병렬성을 향상시키기 위해서 지금까지 개발된 최소 종속 거리 분할 방법, Polychronopoulous 분할 방법, 그리고 최초 종속 분할 방법과 같은 세 가지 루프 분할 방법을 소개하며, 기존의 분할 방법의 문제점들을 제시한다. 그리고, 기존의 세 가지 루프 분할 방법 중에서 가장 효과적인 최초 종속 분할 방법을 확장하여 병렬성을 향상시킨 보다 강력한 루프 분할 방법을 제안한다 제안된 알고리즘은 역 종속성일 경우와 gcd(최대공약수)값이 1보다 클 경우와 같이 최초 종속 분할 방법에서 해결하지 못한 문제점들을 해결하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2060-2065
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• 2003

Aeolian tone generation from a two dimensional circular cylinder is numerically investigated via direct numerical simulation and hydrodynamic-acoustic splitting method. All governing equation are spatially discretized with the sixth-order compact scheme and fourth-order Runge-Kutta method to avoid excessive numerical dissipations and dispersions of acoustic quantities. Comparisons of two results show that the previous splitting method can not accurately predict the aeroacoustic noise of wall bounded shear flow. In this study, a perturbation viscous term and a new energy equation have been developed. This modified splitting method accurately predicts aeroacoustic noise from wall-bounded shear flow. The present results agree very well with the direct numerical simulation solution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.709-714
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• 2000

A splitting method for the direct numerical simulation of solid-liquid mixtures is presented, where a symmetric pressure equation is newly proposed. Through numerical experiment, it is found that the newly proposed splitting method works well with a matrix-free formulation fer some bench mark problems avoiding an erroneous pressure field which appears when using the conventional pressure equation of a splitting method. When deriving a typical pressure equation of a splitting method, the motion of a solid particle has to be approximated by the 'intermediate velocity' instead of treating it as unknowns since it is necessary as a boundary condition. Therefore, the motion of a solid particle is treated in such an explicit way that a particle moves by the known form drag (pressure drag) that is calculated from the pressure equation in the previous step. From the numerical experiment, it was shown that this method gives an erroneous pressure field even for the very small time step size as a particle velocity increases. In this paper, coupling the unknowns of particle velocities in the pressure equation is proposed, where the resulting matrix is reduced to the symmetric one by applying the projector of the combined formulation. It has been tested over some bench mark problems and gives reasonable pressure fields.

• International Journal of Contents
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• 제2권4호
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• pp.8-11
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• 2006

This paper describes several loop partitioning techniques such as loop splitting method by thresholds and Polychronopoulos' loop splitting method for exploiting parallelism from single loop which already developed. We propose improved loop splitting method for maximizing parallelism of single loops with non-constant dependence distances. By using the distance for the source of the first dependence, and by our defined theorems, we present generalized and optimal algorithms for single loops with non-uniform dependences. The algorithms generalize how to transform general single loops into parallel loops.

• International Journal of Contents
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• 제3권3호
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• pp.15-19
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• 2007

We review some loop partitioning techniques such as loop splitting method by thresholds and Polychronopoulos' loop splitting method for exploiting parallelism from single loop which already developed. We propose improved loop splitting method for maximizing parallelism of single loops with non-constant dependence distances. By using the iteration and distance for the source of the first dependence, and by our defined theorems, we present generalized and optimal algorithms for single loops with non-uniform dependences. The algorithms generalize how to transform general single loops with one dependence as well as with multiple dependences into parallel loops.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1067-1074
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• 2011

In this paper, a preconditioned mixed-type splitting iterative method for solving the linear systems Ax = b is presented, where A is a Z-matrix. Then we also obtain some results to show that the rate of convergence of our method is faster than that of the preconditioned AOR (PAOR) iterative method and preconditioned SOR (PSOR) iterative method. Finally, we give one numerical example to illustrate our results.

• 한국음향학회지
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• 제21권1호
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• pp.69-72
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• 2002

부호책 설계에 사용되는 초기 부호책을 얻기 위해 수정된 미소분리 방법을 제안한다. 제안된 방법은 다른 클래스에 비해 소속되는 학습벡터가 다수 소속되거나 자승오차가 작은 클래스에 대표벡터를 더 많이 할당한다는 원리를 적용한다. 기존 K-means 알고리즘과 참고문헌 (5)에서 제안한 방법을 적용하여 설계된 부호책의 성능을 평가할 때, 두 경우 모두 제안된 방법에 의해 얻어진 초기 부호책을 사용하는 것이 기존 미소분리 방법에 의한 초기 부호책을 사용하는 것보다 우수한 결과를 나타낸다.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1167-1178
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• 2011

In this paper, we further investigate the local Hermitian and skew-Hermitian splitting (LHSS) iteration method and the modified LHSS (MLHSS) iteration method for solving generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. When A is non-symmetric positive definite, the convergence conditions are obtained, which generalize some results of Jiang and Cao [M.-Q. Jiang and Y. Cao, On local Hermitian and Skew-Hermitian splitting iteration methods for generalized saddle point problems, J. Comput. Appl. Math., 2009(231): 973-982] for the generalized saddle point problems to generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. Numerical experiments show the effectiveness of the iterative methods.

• Coupled systems mechanics
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• 제1권4호
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• pp.325-343
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• 2012

We present different numerical methods for solving the shallow shelf equations with basal drag (SSAB). An alternative approach of splitting the SSAB equation into a Laplacian and diagonal shift operator is discussed with respect to the underlying eigenvalue problem. First, we solve the equations using standard methods. Then, the coupled equations are decomposed into operators for membranes stresses, basal shear stress and driving stress. Applying reasonable parameter values, we demonstrate that the operator of the membrane stresses is much stiffer than the operator of the basal shear stress. Here, we could apply a new splitting method, which alternates between the iteration on the membrane-stress operator and the basal-shear operator, with a more frequent iteration on the operator of the membrane stresses. We show that this splitting accelerates and stabilize the computational performance of the numerical method, although an appropriate choice of the standard method used to solve for all operators in one step speeds up the scheme as well.

• 화약ㆍ발파
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• 제28권1호
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• pp.63-70
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• 2010

본 연구는 유압력을 이용한 할암공법의 진동 및 소음크기에 대한 현장 적용성 판단을 위해 축사와 노후된 주택구조물 근접지역에서 진동과 소음의 크기를 검토하였다. 검토는 할암공법의 작업과정별로 천공, 절개, 집토 및 상차에 따라 발생되는 진동과 소음의 크기를 근접된 위치(10m~80m)에서 측정 분석하여 대상지역에 설정된 진동과 소음의 허용수준과 비교 하였다. 그 결과 국토해양부의 발파공법 분류에 의해 미진동굴착공법으로 할암 공법을 적용하여도 소음도의 영향은 고려되어야 하는 것으로 확인되었다.