• Title/Summary/Keyword: challenging problems

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Nonlinear programming approach for a class of inverse problems in elastoplasticity

  • Ferris, M.C.;Tin-Loi, F.
    • Structural Engineering and Mechanics
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    • v.6 no.8
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    • pp.857-870
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    • 1998
  • This paper deals with a special class of inverse problems in discrete structural plasticity involving the identification of elastic limits and hardening moduli on the basis of information on displacements. The governing equations lead naturally to a special and challenging optimization problem known as a Mathematical Program with Equilibrium Constraints (MPEC), a key feature of which is the orthogonality of two sign-constrained vectors or so-called "complementarity" condition. We investigate numerically the application of two simple algorithms, both based on the use of the general purpose nonlinear programming code CONOPT accessed via the GAMS modeling language, for solving the suitably reformulated problem. Application is illustrated by means of two numerical examples.

RECENT ADVANCES IN DOMAIN DECOMPOSITION METHODS FOR TOTAL VARIATION MINIMIZATION

  • LEE, CHANG-OCK;PARK, JONGHO
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.24 no.2
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    • pp.161-197
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    • 2020
  • Total variation minimization is standard in mathematical imaging and there have been numerous researches over the last decades. In order to process large-scale images in real-time, it is essential to design parallel algorithms that utilize distributed memory computers efficiently. The aim of this paper is to illustrate recent advances of domain decomposition methods for total variation minimization as parallel algorithms. Domain decomposition methods are suitable for parallel computation since they solve a large-scale problem by dividing it into smaller problems and treating them in parallel, and they already have been widely used in structural mechanics. Differently from problems arising in structural mechanics, energy functionals of total variation minimization problems are in general nonlinear, nonsmooth, and nonseparable. Hence, designing efficient domain decomposition methods for total variation minimization is a quite challenging issue. We describe various existing approaches on domain decomposition methods for total variation minimization in a unified view. We address how the direction of research on the subject has changed over the past few years, and suggest several interesting topics for further research.

Efficient Elitist Genetic Algorithm for Resource-Constrained Project Scheduling

  • Kim, Jin-Lee
    • Korean Journal of Construction Engineering and Management
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    • v.8 no.6
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    • pp.235-245
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    • 2007
  • This research study presents the development and application of an Elitist Genetic Algorithm (Elitist GA) for solving the resource-constrained project scheduling problem, which is one of the most challenging problems in construction engineering. Main features of the developed algorithm are that the elitist roulette selection operator is developed to preserve the best individual solution for the next generation so as to obtain the improved solution, and that parallel schedule generation scheme is used to generate a feasible solution to the problem. The experimental results on standard problem sets indicate that the proposed algorithm not only produces reasonably good solutions to the problems over the heuristic method and other GA, but also can find the optimal and/or near optimal solutions for the large-sized problems with multiple resources within a reasonable amount of time that will be applicable to the construction industry. This paper will help researchers and/or practitioners in the construction project scheduling software area with alternative means to find the optimal schedules by utilizing the advantages of the Elitist GA.

Navigation algorithm for a mobile robot by using the hybrid structure (하이브리드 구조를 사용한 이동 로봇의 주행 방법)

  • Park, Il;Kwon, Young D.;Lee, Jin S.
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.7
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    • pp.1-10
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    • 1996
  • There are many challenging problems in mobile robot navigation. As an example, a mobile robot may wander around in local minimum and may wiggle when it moves through a narrow corridor. In addition, the real time obstacle avoidance and the posture control of mobile robot are also very improtant problems. To address these problems, a navigation algorithm which is composed o freal time obstacle avoidance algorithm and a global path planner (GPP) that genrates the shortest path is presented. In this paper, the global path planner reduce the calculation time by reducing the dta to be handled. Also it can make a real time obstacle avoidance by using the fuzzy logic inference. So the presented algorithm provide a stable navigastion for the mobile robot when it fall into the unstable navigation.

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-A Study on the Sexist Problems in Korean Family and Feminist Family Therapy- (한국가적에서의 성불평등적 문제들과 여권론적 가족치료에 관한 고찰)

  • 최연실
    • Journal of the Korean Home Economics Association
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    • v.32 no.2
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    • pp.145-160
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    • 1994
  • This paper reviews the feminist approach in family therapy field as a proper intervention for the sexist problems in Korean family. First this paper identifies the sexist problems according to the traditional family ideology structure and value conflicts due to the change of society in Korean family and analyses those problems referred to the actual situation of family counseling and therapy. Second this paper introduces the background for the emergence of the feminist family therapy. The feminist approach in family therapy had been emerged since the woman's psychology and feminist therapy appeared in psychology by the influence of women's movement in late 1960s Third the critiques to the existed family therapy from the viewpoint of feminist family therapy are raised. this approach which is challenging the existed family therapy and criticizing the main theoretical models especially emphasizes gender as a primary factor in the approaches of family problems and includes all the aspects of feminism an awareness of sexism and attempts to counteract the ways in which family therapy may reinforce women's surbodinate position. Fourth the techniques of feminist family therapy and the training methods for feminist family therapists are explained. this approach attempts to develop the clinical skills teaching tools and techniques to incorporate the feminist perspective into family therapy practices and proposes the various education and training methods. Finally this paper reviews interests in the feminist family therapy in Korea an has good prospects of increase of it.

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A Study on Optimal Power Flow Using Interior Point Method (Interior Point Method를 이용한 최적조류계산 알고리듬 개발에 관한 연구)

  • Kim Balho H.
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.9
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    • pp.457-460
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    • 2005
  • This paper proposes a new Interior Point Method algorithm to improve the computation speed and solution stability, which have been challenging problems for employing the nonlinear Optimal Power Flow. The proposed algorithm is different from the tradition Interior Point Methods in that it adopts the Predictor-Corrector Method. It also accommodates the five minute dispatch, which is highly recommenced in modern electricity market. Finally, the efficiency and applicability of the proposed algorithm is demonstrated with a case study.

An Analysis of Personal Computer Productivity Improvement through Factory Automation (생산자동화에 따른 컴퓨터공장의 생산성 변화)

  • Yoo, In-Sun;Kim, Byung-Jin
    • IE interfaces
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    • v.7 no.2
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    • pp.133-144
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    • 1994
  • The problem of productivity improvement is one of the most challenging problems facing the world economy. This paper studies an analysis of improving personal-computer(PC) company productivity through factory automation. It attempts to analyze value added productivity at the company level. The index measured will effectively help managers supervise their companys. This study justifies that the proposed approach will stimulate manager's profit-motivation by providing them with value-oriented management instead of quantity-oriented method.

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A Process Improvement of the SMPS Assembly Line Using Motion Study and Line Balancing Techniques (동작 연구 및 라인 발란싱을 활용한 SMPS 조립라인의 공정개선 사례)

  • Lee, Sang-Young;Hong, Sung-Hoon;Kim, Jin-Hwan
    • IE interfaces
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    • v.11 no.3
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    • pp.155-166
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    • 1998
  • The productivity and quality are most challenging problems facing all companies. This paper presents a process improvement of the SMPS(switching mode power supply) assembly line through elimination of unnecessary operations, a proper factory layout, motion study, and line balancing techniques. The proposed assembly line increases the productivity by 23.9%, and decrease the proportion of nonconforming items by 48.9%.

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A Study on Optimal Power Flow Using Interior Point Method (Interior Point Method를 이용한 최적조류계산 알고리듬 개발에 관한 연구)

  • Kim, Bal-Ho H.;Song, Kyung-Bin
    • Proceedings of the KIEE Conference
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    • 2005.07a
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    • pp.852-854
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    • 2005
  • This paper proposes a new Interior Point Method algorithm to improve the computation speed and solution stability, which have been challenging problems for employing the nonlinear Optimal Power Flow. The proposed algorithm is different from the traditional Interior Point Methods in that it adopts the Predictor-Corrector Method. It also accommodates the five minute dispatch, which is highly recommended in modern electricity market. Finally, the efficiency and applicability of the proposed algorithm is demonstrated with a case study.

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Study for the reliability indices in the distribution system (배전선로 공급 신뢰도에 관한 연구)

  • Cho, Nam-Hun;Yoon, Tae-Sang;Ha, Bok-Nam
    • Proceedings of the KIEE Conference
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    • 2000.11a
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    • pp.70-72
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    • 2000
  • The basic function of a modern electric power system is to provide electric power to its customers at the lowest possible cost with acceptable reliability levels. The two aspects of economics and reliability often conflict and present power system managers, planners and operators with a wide range of challenging problems. Utilities may also be willing to provide higher reliability of power supply at no increased customer cost. Decision-making is a difficult task. In this paper, we present a method to calculate the optimal values of reliability indices for sectionalizing distribution line.

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