• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.3
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• pp.215-225
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• 1996

For an undirected stochastic network G, the 2-terminal reliability of G, R(G) is the probability that the specific two nodes (called as terminal nodes) are connected in G. A. typical network reliability problem is to compute R(G). It has been shown that the computation problem of R(G) is NP-hard. So, any algorithm to compute R(G) has a runngin time which is exponential in the size of G. If by some means, the problem size, G is reduced, it can result in immense savings. The means to reduce the size of the problem are the reliability preserving reductions and graph decompositions. We introduce a net set of reliability preserving reductions : the $K^{4}$ (complete graph of 4-nodes)-chain reductions. The total number of the different $K^{4}$ types in R(G), is 6. We present the reduction formula for each $K^{4}$ type. But in computing R(G), it is possible that homeomorphic graphs from $K^{4}$ occur. We devide the homemorphic graphs from $K^{4}$ into 3 types. We develop the reliability preserving reductions for s types, and show that the remaining one is divided into two subgraphs which can be reduced by $K^{4}$-chain reductions 7 polygon-to-chain reductions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1429-1433
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• 2008

In this paper, we consider the design method of robust guaranteed cost controller for discrete-time singular systems with norm-bounded time-varying parameter uncertainty. In order to get the optimum(minimum) value of guaranteed cost, an optimization problem is given by linear matrix inequality (LMI) approach. The sufficient condition for the existence of controller and the upper bound of guaranteed cost function are proposed in terms of strict LMIs without decompositions of system matrices. Numerical examples are provided to show the validity of the presented method.

• ETRI Journal
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• v.45 no.1
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• pp.138-149
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• 2023

In this study, the problem of blind signal separation for coprime planar arrays is investigated. For coprime planar arrays comprising two uniform rectangular subarrays, we link the signal separation to the tensor-based model called coupled canonical polyadic decomposition (CPD) and propose an improved coupled trilinear decomposition approach. The output data of coprime planar arrays are modeled as a coupled tensor set that can be further interpreted as a coupled CPD model, allowing a signal separation to be achieved using coupled trilinear alternating least squares (TALS). Furthermore, in the procedure of the coupled TALS, a Vandermonde structure enforcing approach is explicitly applied, which is shown to ensure fast convergence. The results of Monto Carlo simulations show that our proposed algorithm has the same separation accuracy as the basic coupled TALS but with a faster convergence speed.

• 한국노년학
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• v.32 no.3
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• pp.759-776
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• 2012

This study analysed the income-related health inequality of the aged in Korea applied to EQ-5D. Two decompositions were used in analysis. One was the decomposition of income-related health inequality into six different dimensions of EQ-5D, and the other was to decompose it by sub-group such as sex, region, existence of spouse. The results are summarized as follows. First, the health concentration index(CI) of the aged was .0254, which meant that there were pro-rich inequality in elderly people's health levels. The same patterns were also seen in the analysis of different dimensions of EQ-5D such as mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Second, mobility accounted for 35.8% of total EQ-5D score, most contributing to CI of the dimensions of EQ-5D. The CIs by the dimensions ranged from .0091 for mobility to .0013 for self-care. Third, The decompositions by sub-groups showed that the contributions of sex, region, and existence of spouse to health inequality was similar to each other, all of three sub-groups accounted for 10 % of inequality respectively. Fourth, the inequality within group was higher in female group, rural area, and the aged without spouse. The average health level of these groups was lower than that of the other ones, too. These facts indicated that old women, the aged without spouse, and the elderly in rural area were the most vulnerable groups in health problems. Therefore, it is necessary to pay more attention to health problems of these groups in the policy making of health security and social welfare services.