• International Journal of Contents
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• 제17권1호
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• pp.54-60
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• 2021

The aim of this study was to identify factors influencing problem drinking among the Echo Generation in South Korea and provide basic data for early intervention and mediation of problem drinking among the Echo Generation. This descriptive study performed a secondary analysis of raw data from the 2018 Korean National Health and Nutrition Examination Survey and used responses for problem drinking items from 999 Echo Generation participants born between 1979 and 1992. This study comprehensively investigated sociodemographic and health-related factors influencing problem drinking among the Echo Generation. SPSS WIN program (version 26.0) was used for data analysis. Gender (β=-.32, p<.001), education level (β=.10, p=.002), white-collar workers out of job (β=-.09, p=.041), and depression (β=.11, p<.001) were identified as factors that influenced problem drinking among the Echo Generation. Results of this study suggest that in order to prevent problem drinking among the Echo Generation, there should be user-customized prevention education and intervention programs.

• Industrial Engineering and Management Systems
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• 제8권1호
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• pp.22-28
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• 2009

We consider facility layout problems, where mn facility units are assigned into mn cells. These cells are arranged into a rectangular pattern with m rows and n columns. In order to solve this cell type facility layout problem, many approximation algorithms with improved local search methods were studied because it was quite difficult to find exact optimum of such problem in case of large size problem. In this paper, new algorithms based on Simulated Annealing (SA) method with two neighborhood generation methods are proposed. The new neighborhood generation method adopts the exchanging operation of facility units in accordance with adjacent preference. For evaluating the performance of the neighborhood generation method, three algorithms, previous SA algorithm with random 2-opt neighborhood generation method, the SA-based algorithm with the new neighborhood generation method (SA1) and the SA-based algorithm with probabilistic selection of random 2-opt and the new neighborhood generation method (SA2), are developed and compared by experiment of solving same example problem. In case of numeric examples with problem type 1 (the optimum layout is given), SA1 algorithm could find excellent layout than other algorithms. However, in case of problem type 2 (random-prepared and optimum-unknown problem), SA2 was excellent more than other algorithms.

• 산업공학
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• 제20권2호
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• pp.186-194
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• 2007

Recent deregulation of Korean electricity industry has made each power generation company pay more attention to maximizing its own profit instead of minimizing the overall system operation cost while guaranteeing system security. Electricity power generation problem is typically defined as the problem of determining both the on and off status and the power generation level of each generator under the given fuel constraints, which has been known as Profit-Based Unit Commitment (PBUC) problem. To solve the PBUC problem, the previous research mostly focused on devising Lagrangian Relaxation (LR) based heuristic algorithms due to the complexity of the problem and the nonlinearity of constraints and objectives. However, these heuristic approaches have been reported as less practical in real world applications since the computational run time is usually quite high and it may take a while to implement the devised heuristic algorithms as software applications. Especially when considering long-term planning problem which spans at least one year, the complexity becomes higher. Therefore, this paper proposes an explicit column generation algorithm using power generation patterns and the proposed algorithm is successfully applied to a Korean power generation company. The proposed scheme has a robust structure so that it is expected to extend general PBUC problems.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제29권3호
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• pp.533-551
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• 2015

본 연구에서는 '동일한' 문제 조건으로부터 생성과 재구성을 모두 경험할 수 있는 문제제기 활동을 적용하되, 활동을 세분화하여 학생들의 자주적인 활동을 강조한 활동과 학생들의 보편적 사고를 유도하며 교사 안내가 수반되는 활동으로 구분하여 이에 대한 두 절차를 구안하고, 이 두 활동에 의거하여 문제생성과 재구성 활동에 관해 탐색하고자 한다. 이를 위하여, 본 연구에서는 예비교사들을 대상으로 연구자가 구안한 문제제기 활동을 적용한 실험 수업 후 설문조사를 통하여 문제생성과 재구성에 대한 난이도 및 흥미도, 인지적 정의적 측면에서의 효과, 그리고 수학 수업 및 평가에서의 활용성 등을 탐색하였다. 그 결과, 문제생성은 창의력을 증진시키고 수학에 대한 흥미를 유발하며, 문제 재구성은 문제 해결력 향상에 도움이 되고 자신감을 길러주는 것으로 나타났다. 또한 수업 상황에서는 문제생성 활동이 더 효과적이고, 평가 상황에서는 문제재구성 활동이 더 효과적인 것으로 나타났으나 각 상황에서 문제생성과 재구성에 대한 응답의 차이가 크지 않았으므로 두 활동 모두 수업 및 평가에 적용이 가능할 것으로 판단된다. 따라서 교사는 학습자의 수준, 가르칠 영역, 진도 등을 고려하여 수업 및 평가 상황에서 문제생성과 재구성 활동을 적절한 시기에 알맞게 적용함으로써 학습자의 인지적, 정의적 성취의 함양을 돕도록 해야 할 것이다.

• 신재생에너지
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• 제2권3호
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• pp.23-30
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• 2006

Need developments of substitute energy to solve problem of global warming by excess use of fossil energy, excess discharge of carbon dioxide. wind power generation system is all-important energy in next generation as clean energy. Environmental pollution of wind power generation system is not exhausted entirely. And, electric-power generation system cost is cheap than other energy. Wind Generation system that is supplied much present is most horizontality style blade structure. But, Horizontal style structure is serious noise and there is problem in stability of blade. We designed special blade solve to this problem. And, manufactured vertical axis wind power generation system because using blade. Also, developed assistance power generator to increase driving efficiency ago wind power generation. We expect this devices that is such cover shortcoming of wind power generation system.

• 한국경영과학회지
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• 제25권3호
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• pp.1-15
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• 2000

In this paper, we propose a practical cut generation method based on the Chvatal-Gomory procedure for the (0, 1)-Knapsack problem with a variable capacity. For a given set N of n items each of which has a positive integral weight and a facility of positive integral capacity, a feasible solution of the problem is defined as a subset S of N along with the number of facilities that can satisfy the sum of weights of all the items in S. We first derive a class of valid inequalities for the problem using Chvatal-Gomory procedure, then analyze the associated separation problem. Based on the results, we develop an affective cut generation method. We then analyze the theoretical strength of the inequalities which can be generated by the proposed cut generation method. Preliminary computational results are also presented which show the effectiveness of the proposed cut generation method.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.613-616
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• 2000

This paper considers the problem of subway crew scheduling. Crew scheduling is concerned with finding a minimum number of assignments of crews to a given timetable satisfying various restrictions. Traditionally, crew scheduling problem has been formulated as a set covering or set partitioning problem possessing exponentially many variables, but even the LP relaxation of the problem is hard to solve due to the exponential number of variables. In this paper, we propose two basic techniques that solve the problem in a reasonable time, though the optimality of the solution is not guaranteed. To reduce the number of variables, we adopt column-generation technique. We could develop an algorithm that solves column-generation problem in polynomial time. In addition, the integrality of the solution is accomplished by variable-fixing technique. Computational results show column-generation makes the problem of treatable size, and variable fixing enables us to solve LP relaxation in shorter time without a considerable increase in the optimal value. Finally, we were able to obtain an integer optimal solution of a real instance within a reasonable time.

• Management Science and Financial Engineering
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• 제10권1호
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• pp.97-106
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• 2004

In this paper, we propose an effective cut generation method based on the Chvatal-Gomory procedure for a variable-capacity (0,l)-Knapsack problem with two general integer variables. We first derive a class of valid inequalities for the problem using Chvatal-Gomory procedure, then analyze the associated separation problem. Based on the results, we show that there exists a pseudo-polynomial time algorithm to solve the separation problem. By analyzing the theoretical strength of the inequalities which can be generated by the proposed cut generation method, we show that generated inequalties define facets under mild conditions. We also extend the result to the case in which a nontrivial upper bound is imposed on a general integer variable.

• 공학교육연구
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• 제2권1호
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• pp.17-23
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• 1999

인터넷을 이용한 여러 가지의 서비스 중에서도 학습 관리를 인터넷에서 처리할 수 있도록 하는 시스템이 속속 개발되고 있다. 본 논문에서는 현재 상용화 된 인터넷용 문제 출제 및 평가시스템의 성능을 비교 분석하고 이를 학습에 적용하기 위한 구체적인 방법들을 제시한 후 국내의 독자적인 기술력으로 저자가 개발한 JPGEM(Java Problem Generation and Evaluation Module) 에 대하여 간략히 설명하고자 한다. JPGEM 은 종합 문제 출제 및 평가 시스템으로 자바를 이용하여 개발되었으며, 개별 교과목에 관한 문제를 임의로 출제할 수 있다. 총 5가지의 문제 출제 유형을 지원하고 시험 결과를 서버에 저장하여 학습자의 학습 및 능력을 평가할 수 있도록 지원한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.252-254
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• 2004

This paper studies power quality problem of utility interconnected distributed generation. Recently, electronic devices that are sensitive to power quality have been increasing. Both utility and customer are interested in power quality problem. Therefore, we studied an effect of utility power quality caused by distributed generation. We detect and analysis voltage sag which is one of power quality indicator. Also, we used Matlab to simulate power quality problem.