• Structural Engineering and Mechanics
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• v.45 no.4
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• pp.495-519
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• 2013

This paper investigates properties of integral operators in complex variable boundary integral equation in plane elasticity, which is derived from the Somigliana identity in the complex variable form. The generalized Sokhotski-Plemelj's formulae are used to obtain the BIE in complex variable. The properties of some integral operators in the interior problem are studied in detail. The Neumann and Dirichlet problems are analyzed. The prior condition for solution is studied. The solvability of the formulated problems is addressed. Similar analysis is carried out for the exterior problem. It is found that the properties of some integral operators in the exterior boundary value problem (BVP) are quite different from their counterparts in the interior BVP.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.3
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• pp.145-156
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• 2002

Business managers are often required to use LP problems to deal with uncertainty inherent in decision making due to rapid changes in today＇s business environments. Uncertain parameters can be easily formulated in the two-stage stochastic LP problems. However, since solution methods are complex and time-consuming, a common approach has been to use modified formulations to provide upper and lower bounds on the two-stage stochastic LP problem. One approach is to use an expected value problem, which provides upper and lower bounds. Another approach is to use “walt-and-see” problem to provide upper and lower bounds. The objective of this paper is to propose a modified approach of “wait-and-see” problem to provide an upper bound and to compare the relative error of optimal value with various upper and lower bounds. A computing experiment is implemented to show the relative error of optimal value with various upper and lower bounds and computing times.

• The Research Journal of the Costume Culture
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• v.5 no.1
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• pp.71-83
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• 1997

It is the important situation that the fashion industry is faced to enormous changes in the nation and worldwide market. To cope with this situations, it is necessary to clarify that the concept of fashion design and its process. This study was conducted as followings : 1. Fashion design is the process of problem solving including the steps of understanding problem, visualizing the image of a design concept. 2. The systematic and intuitive approach is harmonized to solve the process of fashion design. 3. The step of understanding problem is consist of the analysis of environments, the explanation of problem, the determination of purposes, the definition of problem and the visualizing the image of a design concept. 4. In the step of the visualizing the image of a design concept, the intuitive approaches can be clarifies as the importance of start, the step by step process, the determination of a design concept, the fixations of an image, the image realization through real objects, the diminution a difference between a concept and a visualizing the image and the necessity of exercises.

• 한국데이터정보과학회:학술대회논문집
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• 2005.10a
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• pp.71-84
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• 2005

The Fieller-Creasy problem involves statistical inference about the ratio of two independent normal means. It is difficult problem from either a frequentist or a likelihood perspective. As an alternatives, a Bayesian analysis with noninformative priors may provide a solution to this problem. In this paper, we extend the results of Yin and Ghosh (2001) to unbalanced sample case. We find various noninformative priors such as first and second order matching priors, reference and Jeffreys' priors. The posterior propriety under the proposed noninformative priors will be given. Using real data, we provide illustrative examples. Through simulation study, we compute the frequentist coverage probabilities for probability matching and reference priors. Some simulation results will be given.

• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.85-97
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• 2003

An indefinite stochastic linear-quadratic(LQ) optimal control problem with cross term over an infinite time horizon is studied, allowing the weighting matrices to be indefinite. A systematic approach to the problem based on semidefinite programming (SDP) and .elated duality analysis is developed. Several implication relations among the SDP complementary duality, the existence of the solution to the generalized Riccati equation and the optimality of LQ problem are discussed. Based on these relations, a numerical procedure that provides a thorough treatment of the LQ problem via primal-dual SDP is given: it identifies a stabilizing optimal feedback control or determines the problem has no optimal solution. An example is provided to illustrate the results obtained.

• Journal of The Korean Association For Science Education
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• v.30 no.3
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• pp.366-374
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• 2010

The purpose of this study was grouping students' perception types on the unexpected results in experiments, and looking into how the problem-solving experiment affected the change of these perception types. In order to answer this, interview data were analyzed in terms of perception types, and through analysis of questionnaires carried out at the beginning and the end of the semester, the change of perception types was researched. As a result, perception types of students divided into 'the difference between theory and practice,' 'inexperience of experiment skill,' and 'No reading between lines in manual.' After performing the problem-solving experiment for one semester, the perception of 'the difference between theory and practice' declined, and the desire for 'reading between lines' increased, so the problem-solving experiment influenced on the change of perception positively.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.505-513
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• 2017

In this paper, a receding contact problem for an elastic layer resting on a half plane is considered. The layer is pressed by two rectangular stamps placed symmetrically. It is assumed that the contact surfaces are frictionless and only compressive traction can be transmitted through the contact surfaces. In addition the effect of body forces is neglected. Firstly, the problem is solved analytically based on theory of elasticity. In this solution, the problem is reduced into a system of singular integral equations in which half contact length and contact pressures are unknowns using boundary conditions and integral transform techniques. This system is solved numerically using Gauss-Jacobi integral formulation. Secondly, two dimensional finite element analysis of the problem is carried out using ANSYS. The dimensionless quantities for the contact length and the contact pressures are calculated under various stamp size, stamp position and material properties using both solutions. The analytic results are verified by comparison with finite element results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.231-239
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• 1987

Distribution system is one of large and complicated sytem, consisted of a great number of components. Therefore efficient operation based on precise analysis and computation methods is indispensable accommodating growing loads. This paper describes an optimal operation problem to relieve overload flow in radial distribution systems by using modified block model. The problem is formulated as a network problem of synthesizing the optimal spanning tree in a graph, branch and bound method is used for the optimization. Especially modified block model proposed in this paper is validated more practical than conventional model. These methods can be applied to two types of distribution system problems such as, 1) planning problem to check the capability of relieving overload at normal rating, 2) emergency operation problem to determine switching scheme for minimizing customer loads affected by a fault. Examples of application to these problems are discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.04a
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• pp.48-51
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• 2009

Excessive wavy surfaces formed by a cold or hot-rolling process in a thin plate degrade the value of the plate significantly, which is called flatness problem in the industry. It is a result of post-buckling due to the residual stress caused by the rolling process. A unique difficulty of the problem as a buckling problem is that the buckling length is not given but has to be found. a new approach is developed to solve the flatness problem by extending a classic post-buckling analysis method based on the energy principle. The approach determines the buckling length and amplitude. The new solution approach can be used to determine the condition for the maximum rolling production that does not cause the flatness problem.

• Communications of Mathematical Education
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• v.23 no.2
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• pp.175-196
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• 2009

In this paper we analyze Ziv's geometrical differentiated teaching and learning materials using inner structure of mathematics problems. In order to analyze inner structure of mathematics problems we in detail describe problem solving process, and extract main frame from problem solving process. We represent inner structure of mathematics problems as tree including induced relations. As a result, we characterize low-level problems and middle-level problems, and find some differences between low-level problems and middle-level problems.