• Journal of the Korean Society of Marine Environment & Safety
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• v.6 no.1
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• pp.23-33
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• 2000

This paper is concerned with finding the global optimal solutions for the redundancy optimization problems in series-parallel systems related with system safety. This study transforms the difficult problem, which is classified as a nonlinear integer problem, into a 0/1 IP(Integer Programming) by using binary integer variables. And the global optimal solution to this problem can be easily obtained by applying GAMS (General Algebraic Modeling System) to the transformed 0/1 IP. From computational results, we notice that GA(Genetic Algorithm) to this problem, which is, to our knowledge, known as a best algorithm, is poor in many cases.

• Korean Journal of Human Ecology
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• v.13 no.6
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• pp.875-889
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• 2004

The purpose of this study Is to analyze the homepage contents of an auction site on the Internet. This study collected 459 cases of purchasing and selling notes, and classified them into three types. The finding showed that some of the most frequently-occurring consumer problems are concerned with delivery and return, and sellers manner. On the other hand, consumers' manner is important to sellers. The auction site itself has problems with consultation and its own system.

• Advances in Computational Design
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• v.1 no.1
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• pp.87-103
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• 2016

This paper adopts and investigates the non-dominated sorting approach for extending the single-objective Cuckoo Search (CS) into a multi-objective framework. The proposed approach uses an archive composed of primary and secondary population to select and keep the non-dominated solutions at each generation instead of pairwise analogy used in the original Multi-objective Cuckoo Search (MOCS). Our simulations show that such a low computational complexity approach can enrich CS to incorporate multi-objective needs instead of considering multiple eggs for cuckoos used in the original MOCS. The proposed MOCS is tested on a set of multi-objective optimization problems and two well-studied engineering design optimization problems. Compared to MOCS and some other available multi-objective algorithms such as NSGA-II, our approach is found to be competitive while benefiting simplicity. Moreover, the proposed approach is simpler and is capable of finding a wide spread of solutions with good coverage and convergence to true Pareto optimal fronts.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.299-303
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• 2008

In this paper, we discuss the schedule problems for Korean Professional Baseball League (KPBL) and propose approaches to solve these problems by applying Integer Programming. A schedule in a sport league must satisfy lots of constraints on timing such as organizational, attractiveness, and fairness requirements. Organizational requirements cover a set of rules which have to guarantee that all the games can be scheduled according to the regulations imposed by Korean Baseball Organization (KBO). Attractiveness requirements focus on what stadium visitors, television spectators, and the clubs expect, that is, a varied, eventful, and exciting season. Fairness requirements have to guarantee that no team is handicapped or favored in comparison with the others. In addition to finding a feasible schedule that meets all the constraints, the problem addressed in this paper has the additional complexity of having the objective of minimizing the travel costs and every team has the balancing number of the games in home. We formalize the KPBL problem into an optimization problem and adopt the concept of evolution strategy to solve it. Using the method proposed, it is efficient to find better results than approaches developed before.

• Communications of the Korean Mathematical Society
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• v.25 no.1
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• pp.69-82
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• 2010

In this paper, we propose an iterative scheme for finding a common element of the set of solutions of an equilibrium problem and the set of fixed points of an asymptotically k-strict pseudo-contractive mapping in the setting of real Hilbert spaces. We establish some weak and strong convergence theorems of the sequences generated by our proposed scheme. Our results are more general than the known results which are given by many authors. In particular, necessary and sufficient conditions for strong convergence of our iterative scheme are obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.3
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• pp.38-44
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• 2009

This paper presents a new windows application based on 3-D graphics and Text-To-Speech (TTS) for effective management of substation equipment. When problems in a power system occur, inexperienced power system operators may have difficulty in understanding the situation as well as finding suitable countermeasures quickly. This paper addresses an effective scheme to visualizing power system equipment under normal and abnormal conditions using 3-D graphics and animations. In addition, the state variations and the order of maintenance priority of substation equipment are represented by TTS and intuitive methods. The proposed system can help power system operators to more quickly understand the state of power system equipment, and it can provide operators with the suitable countermeasures for minimizing damage caused by equipment problems.

• Journal of the Korean Mathematical Society
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• v.46 no.3
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• pp.561-576
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• 2009

We introduce two iterative algorithms for finding a common element of the set of fixed points of an asymptotically k-strict pseudo-contraction and the set of solutions of a mixed equilibrium problem in a Hilbert space. We obtain some weak and strong convergence theorems by using the proposed iterative algorithms. Our results extend and improve the corresponding results of Tada and Takahashi [16] and Kim and Xu [8, 9].

• Communications of the Korean Mathematical Society
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• v.32 no.3
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• pp.765-778
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• 2017

Finding an initial feasible solution on the central path is the main difficulty of feasible interior-point methods. Although, some algorithms have been suggested to remedy this difficulty, many practical implementations often do not use perfectly centered starting points. Therefore, it is worth to analyze the case that the starting point is not exactly on the central path. In this paper, we propose a weighted-path following interior-point algorithm for solving the Cartesian $P_{\ast}({\kappa})$-linear complementarity problems (LCPs) over symmetric cones. The convergence analysis of the algorithm is shown and it is proved that the algorithm terminates after at most $O\((1+4{\kappa}){\sqrt{r}}{\log}{\frac{x^0{\diamond}s^0}{\varepsilon}}\)$ iterations.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.3
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• pp.163-168
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• 2000

The problems of mixed $H_2/H_{\infty}$ filtering design fer continuous and discrete time linear systems with time delay are investigated. The main purpose is to design a stable mixed $H_2/H_{\infty}$ filter which minimizes the H$_2$Performance measure satisfying a prescribed H$_{\infty}$ norm bound on the closed loop system in continuous-time case and discrete-time case, respectively. The sufficient conditions of existence of filter, the mixed $H_2/H_{\infty}$ filter design method, and the upper bound of performance measure are proposed by LMI(linear matrix inequality) techniques in terms of all finding variables. Also, we present optimization problems in order to get the optimal mixed $H_2/H_{\infty}$ filter in continuous and discrete time case, respectively.

• Korean Journal of Computational Design and Engineering
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• v.17 no.4
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• pp.262-273
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• 2012

We present a novel GPU algorithm to compute outer cell boundaries of 3D arrangement subdivided by a given set of triangles. An outer cell boundary is defined as a 2-manifold surface consisting of subdivided polygons facing outward. Many geometric problems, such as Minkowski sum, sweep volume, lower/upper envelop, Bool operations, can be reduced to finding outer cell boundaries with specific properties. Computing outer cell boundaries, however, is a very time-consuming job and also is susceptible to numerical errors. To address these problems, we develop an algorithm based on GPU with a robust scheme combining interval arithmetic and multi-level precisions. The proposed algorithm is tested on Minkowski sum of several polygonal models, and shows 5-20 times speedup over an existing algorithm running on CPU.