• Communications for Statistical Applications and Methods
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• 제10권2호
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• pp.387-397
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• 2003

Generally, most of researches that need a variable-clustering process use an exploratory factor analysis technique or a divisive hierarchical variable-clustering method based on a correlation matrix. And some researchers apply a object-clustering method to a distance matrix transformed from a correlation matrix, though this approach is known to be improper. On this paper an agglomerative hierarchical variable-clustering method based on a correlation matrix itself is suggested. It is derived from a geometric concept by using variate-spaces and a characterizing variate.

• 한국주조공학회지
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• 제13권5호
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• pp.441-449
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• 1993

SiC particulate reinforced magnesium matrix composites were fabricated by melt stirring method. The effet of several factors on mechanical properties and the efficiency of melt stirring method from the viewpoint of these properties were investigated. The tensile strength increased and the elongation decreased with decrease of the particle size or the increase of the paticulate volume fraction for pure magnesium matrix and Mg-5%Zn alloy matrix composites. A longer stirring time improved the tensile strength of these composites. The tensile strength of Mg-5%Ca alloy matrix composites which shows no uniform paticulate distribution was a little lower than that of matrix alloy. Rapid solidification rate is preferred for the improved tensile strength of these composites. The pure magnesium matrix and Mg-5%Zn alloy matrix composites have tensile strength of about 400MPa. This value agrees with the tensile strength of some magnesium matrix composites fabricated by liquid infiltration method or powder metallurgy method at the same volume fraction of reinforcements of whisker or particle. Therefore, the melt stirring method which has the advantages of simple process is considered to be efficient in fabricating magnesium matrix composites.

• International Journal of Automotive Technology
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• 제2권3호
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• pp.117-122
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• 2001

For a dynamic analysis of a constrained multibody system, it is necessary to have a routine for satisfying kinematic constraints. LU decomposition scheme, which is used to divide coordinates into dependent and independent coordinates, is efficient but has great difficulty near the singular configuration. Other method such as the projection matrix, which is more stable near a singular configuration, takes longer simulation time due to the large amount of calculation for decomposition. In this paper, the row space and the null space of the Jacobian matrix are proposed by using the pseudo-inverse method and the projection matrix. The equations of the motion of a system are replaced with independent acceleration components using the null space of the Jacobian matrix. Also a new hybrid method is proposed, combining the LU decomposition and the projection matrix. The proposed hybrid method has following advantages. (1) The simulation efficiency is preserved by the LU method during the simulation. (2) The accuracy of the solution is also achieved by the projection method near the singular configuration.

• Journal of applied mathematics & informatics
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• 제26권3_4호
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• pp.501-510
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• 2008

In this paper, we first provide a convergence result of the generalized two-stage splitting method for solving a linear system whose coefficient matrix is an H-matrix, and then we provide convergence results of the generalized multisplitting and two-stage multisplitting methods for both a monotone matrix and an H-matrix.

• Journal of applied mathematics & informatics
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• 제18권1_2호
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• pp.59-72
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• 2005

We study convergence of symmetric multisplitting method associated with many different multisplittings for solving a linear system whose coefficient matrix is a symmetric positive definite matrix which is not an H-matrix.

• 대한수학회지
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• 제50권4호
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• pp.755-770
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• 2013

One of the interesting nonlinear matrix equations is the quadratic matrix equation defined by $$Q(X)=AX^2+BX+C=0$$, where X is a $n{\times}n$ unknown real matrix, and A, B and C are $n{\times}n$ given matrices with real elements. Another one is the matrix polynomial $$P(X)=A_0X^m+A_1X^{m-1}+{\cdots}+A_m=0,\;X,\;A_i{\in}\mathbb{R}^{n{\times}n}$$. Newton's method is used to find the symmetric and bisymmetric solvents of the nonlinear matrix equations Q(X) and P(X). The method does not depend on the singularity of the Fr$\acute{e}$chet derivative. Finally, we give some numerical examples.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 1997년도 제11회 하계학술발표회 논문집
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• pp.175-194
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• 1997

The competitive power of technologies is required for survival of enterprises in the social environments that change rapidly. So the strategy of technology development becomes more and more important. For the establishment of strategy, the situational analysis and the forecasting analysis are executed and they include the technology assessment and the technological forecasting. The technology assessment is systematical examination and analysis of the present status of technology. Among the various methods of technology assessment, Matrix Method is one of the usual methods. This research is intended to find out the problems and the difficulties in the current Matrix Method, and to improve the method, finally to help the R&D departments of enterprises applying the method. This suggested matrix(TSM Technology Shift Matrix) method is designed so that one can judge the current situation of technology and future expectation, by moving the matrix which is placed to the upside of the basic matrix.

• 대한전기학회논문지
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• 제32권12호
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• pp.435-440
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• 1983

The methods of forming the bus impedance matrix, which is mainly employed in fault analysis of power system, can be generally classified in catagories, (1) the one being the inverse matrix of bus admittance matrix, and (2) the other the bus impedance matrix succesive formation method by particular algorithms. The former method is theouetically elegant, but the formation and inverse of complex bus admittance matrix for large power system requires too much amounts of computer memory space and computing time. The latter method also requires too much memory space. Therefore, in this paper, an algorithm and computer program is introduced for the formation of a sparse bus impedance matrix which generates only the matching terms of the admittance matrix. So, this method can reduce the computer memory and computing time, and can be applied to fault analysis of large power system by small digital computer.

• 수산해양기술연구
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• 제27권2호
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• pp.125-131
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• 1991

Electrolyte matrix fabrication process can be classifed as hot pressing, tape casting, callendering, electrophoretic deposition. however, these have limits in practice. Hot pressing is cumbersome method, because of careful heating and cooling. Furthermore, the perfected tile is so fragile that it is difficult to fit in a cell. Therefore this method is not adequate for mass production of the electrolyte matrix. Using electrophoretic deposition method, a very thin matrix can be made, but many attempts of the electrolyte embeding were found to be failure. Tape casting and callendering methods are employed in most of the matrix fabrication for the present. But these methods require lots of water as a solvent, so that coating of the LiAlO sub(2) with electrolyte is difficult. Recently, hot roll milling method has been developed and the perfected matrix was proved to be free from crack. The method, however, needs a roller to make a matrix and a perfected matrix is carefully striped off from the cooled roller. Therefore, this method requires a long time due to the cooling process. The author proposes a cold rolling process. On this method, heated slurry of the LiAlO sub(2) mixed with binder, is rolled with a cold roller. The heated slurry dose not adhere to the roller, since contacted hot slurry is rapidly solidified. Therefore fabrication speed is increased, without getting rid of merits of the hot rolling process.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.77-84
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• 2011

연속보를 대상으로 한 재료비선형 전달행렬법을 제시하였으며, Gauss-Lobatto 적분법을 사용하여 보의 강성행렬로부터 전달행렬을 도출한다. 전달행렬법에서는 유한요소해석법과는 달리 각 절점의 자유도 수에 상관없이 일정한 미지값만을 가지게 되므로 선형해석뿐만 아니라 비선형해석에서도 빠른 연산속도를 보인다. 연속보에 대한 비선형 해석의 적용 예를 통한 비교 결과, 재료비선형 전달행렬법이 변위-모멘트, 변위-하중, 곡률-모멘트의 관계에서 유한요소해석법에 비해 효율적인 것으로 평가되었다.