• Transactions of Materials Processing
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• v.9 no.3
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• pp.274-283
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• 2000

A dynamic explicit finite element code for simulating sheet forming processes has been developed. The code utilizes the discrete Kirchhoff shell element and contact force is treated by a conventional penalty method. In order to reduce the computational cost, a new and robust contact searching algorithm has been developed and implemented into the code. In the method, a hierarchical structure of tool segments is built for each tool at the initial stage of the analysis. hierarchical structure is built in a way to divide a box to 8 sub-boxes, 2 in each direction, until the lowest level of the hierarchical structure contains exactly one segment of the tool or empty. Then at each time step, contact is checked from the box to sub-boxes hierarchically for each node. Comparisons of computational results of various examples with the existing ones show the validity of the method.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2007.11a
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• pp.316-321
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• 2007

The hierarchical covering location problem emphasizes the issue of locating of hierarchical facilities in order to maximize the number of customers that can be covered. In the classical HCLP(Hierarchical Covering Location Problem), it is assumed that the customers are covered completely if they are located within a specific distance from the facility, and not covered otherwise. The generalized HCLP is introduced that the coverage of customers is measured to be any real value rather than 0 or 1, where the service level may decrease according to the distance. Mixed integer programming formulation for the generalized HCLP is suggested with a partial coverage of service. Solutions are found using OPL Studio, and are evaluated for various cases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.6
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• pp.933-941
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• 1997

In the analysis of thin elastic structures such as plate and shell-like structures, classical lower-order theories like Kirchhoff and Reissner-Mindin theories are insufficient to describe the behavior of such structures in the region where the state of stresses is complex. On the other hand, the fully three dimensional theory of linear elasticity can provide desired analysis accuracy, but requires expensive computational implementation compared to the classical theories. This paper is concerned with the development of hierarchical models for elastic structures which can be used for hierarchical modeling for the analysis of such structures. Derivation and limit model analysis (when the thickness of structures tends to zero) of hierarchical models are presented together with a introduction of modeling error estimation. Also, numerical results supporting theoretical results are given.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.1
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• pp.161-181
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• 1998

Translating expert knowledge into production rules has been the most difficult and time-consuming when building expert systems (Buchanan et al. 1983). Especially, buidling hierarchical structure, i. e. developing sequential or dominant relationship among production rules is one of the most important and difficult processes. Hierarchical relationship among rules has been typically determined in the course of interviewing human experts. Since this interviewing procedure is rather subjective, however, the hierarchically structured rules produced in terms of interviewing is widely exposed to the severe discussion about their validity (Nisbett and Wilson 1977 : Ericsson and Simon 1980 : Kellog 1982). We thus need an objective method to effectively translate human expert knowledge into structured rules. As such a method, this paper suggests the order anlaysis technique that has been studied in psychometries (Cliff 1977 : Reynolds 1981 : Wise 1983). In this paper we briefly introduce the order analysis and explain how it can be applied to building hierarchical structure of production rules. We also illustrate how bankrupcy prediction rules of small-medium companies can be developed using this order analysis technique. Further, we validata the effectiveness of these rules developed by the order analysis, in comparison with those built by other methods. The rules developed by the proposed outperform those of the other traditional methods in effectively screening the bankrupted firms.

• Health Policy and Management
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• v.21 no.2
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• pp.263-278
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• 2011

As the competition among hospitals become intensified, hospital management is required to carry out more effective marketing and positioning of the hospital. Successful positioning of a hospital requires the knowledge about how the concrete attributes inherent in the medical service associated with the customer values that customers seek eventually in the medical service. Thus, it is required for hospital management to understand which hospital attributes should be emphasized in order to improve the customer values. The hierarchical structure of service attributes can provide valuable information about effective positioning and advertising. To obtain such knowledge, we employed the order analysis technique as an objective means-end chain method. Order analysis is useful for identifying the causal structure among attributes. Thus, we can examine the underlying causal relationship and eventually the vertical structure of hospital selection attributes. For this study, we conducted a survey to obtain 370 responses for the analysis. The result suggests that hospital management had better increase the scale of hospital, improve the services of health care providers, and modernize the hospital facilities and equipments so as to enhance customer values and eventually to lead them to recommend the hospital to others. Our findings would provide the valuable information for hospital management to develop the more effective hospital positioning and marketing strategies.

• Journal of Information Technology Applications and Management
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• v.25 no.4
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• pp.79-114
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• 2018

Although former scholarly studies mostly focus on exploring leadership effectiveness under the traditional hierarchical leader-subordinate relationship, the research of leadership performance for non-hierarchical organizational structures, particularly the mediating factors of higher-order goals, trust-in-leader, and self-efficacy have been ignored. This study, therefore, makes an attempt to ascertain the impacts of transformational leadership on the performance of subordinates through the mediating effects of higher-order goals, trust-in-leader, and self-efficacy and the differences of these effects in the context of multi-level marketing (MLM). Like the small-sample studies adopted by Barling, Weber, and Kelloway [1996], Barling, Slater, and Kelloway [2000] and Bass, Avolio, Jung, and Berson [2003], this study adopts a sample of 123 MLM distributors of an MLM company in Hong Kong, with a high response rate of 80.4%. The results indicate that the mediating effect of self-efficacy between transformational leadership and performance is significant under non-hierarchical organizational structures such as MLM in China.

• ETRI Journal
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• v.5 no.2
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• pp.17-28
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• 1983

This paper deals with the problem of optimally controlling traffic flows in urban transportation traffic networks. For this, a nonlinear discrete-time model of urban traffic network is first suggested in order to handle the phenomenon of traffic flows such as oversaturatedness and/or undersaturatedness. Then an optimal control problem is formulated and a hierarchical optimization technique is applied, which is based upon a prediction-type two-level method of Hirvonen and Hakkala.

• Communications for Statistical Applications and Methods
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• v.2 no.1
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• pp.137-144
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• 1995

Hierarchical Bayes estimations of exchangeable mean vector of a multivariate Poisson distribution are obtained. Since sophiscated analytic integration procedures are needed, the Laplace method is employed in order tocompute these estimations approximately. An example is presented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.22-25
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• 1999

A dynamic explicit finite element code for simulating sheet forming processes has been developed The code utilises the discrete Kirchhoff shell element and contact force is treated by a conventional penalty method. In order to reduce the computational cost a new and robust contact searching algorithm has been developed and implemented into the code. in the method a hierarchical structure of tool segments called a tree structure is built for each tool at the initial stage of the analysis Tree is built in a way to divide a trunk to 8 sub-trunk 2 in each direction until the lowest level of the tree(leaf) contains exactly one segment of the tool. In order to have a well-balanced tree each box on each sub level contains one eighth of the segments. Then at each time step contact line from a node comes out of the surface of the tool. Simulation of various sheet forming processes were performed to verify the validity of the developed code with main focus on he usefulness of the developed contact searching algorithm.

• Journal of the Korean Data and Information Science Society
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• v.12 no.1
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• pp.19-25
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• 2001

Random effects models which describe the dependence via random effects in various correlated data have recently received considerable attention in the biomedical literature. They include mixed linear models (MLMs), generatized linear mixed models (GLMMS) and hierarchical generalized linear models (HGLMs). For the inference Lee and Nelder (2000) proposed the first-and second-order REML (restricted maximum likelihood) methods based on hierarchical-likelihood of tee and Welder (1996). In this paper, for Poisson-gamma HGLMs the new methods are theoretically compared with marginal likelihood methods and both methods are illustrated by two practical examples.