• 한국산학기술학회논문지
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• 제20권2호
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• pp.26-35
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• 2019

데이터센터는 서버, 스토리지, 네트워킹 기기 등을 운영하는 과정에서 냉각시설, 공조시설, 비상발전시설 등 많은 전력이 소비된다. 미국의 경우에는 2004년 데이터센터에서 소비하는 전력은 전체 전력 소비량의 1.8% 정도를 차지하기도 하였다. 데이터센터 산업은 큰 규모로 점진적으로 발전해왔으며, 향후에는 규모가 큰 하이퍼스케일 데이터센터의 수가 늘어날 것으로 전망되고 있다. 하지만 데이터센터의 서버 점유율을 조사해 본 결과, 평균 점유율이 15~20% 정도 밖에 되지 않는 등 서버가 효율적으로 사용되지 않는 문제가 존재하였다. 이러한 현상 및 문제점을 개선하고자 가상머신 마이그레이션 기능을 활용하여 가상머신 재배치 연구를 제안하고자 한다. 본 연구에서는 효과적인 가상머신 재배치를 위해 메타 휴리스틱 기법 중 하나인 화음 탐색법을 활용하였다. 유휴 서버 최대화를 목표로 하는 가상머신 재배치 문제를 설계하였으며 실험을 통해 풀이하였다. 본 연구는 가상머신 재배치를 통해 데이터센터 서버의 절전을 유도하여, 데이터센터의 운영비용을 절감하는 것을 목적으로 한다.

• 국제지역연구
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• 제21권1호
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• pp.25-57
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• 2017

본 연구에서는 R&D 투자를 바탕으로 대규모기업집단 소속 기업의 대리인 문제와 정보비대칭성을 분석한다. 본 연구의 분석을 위하여 우선 대규모기업집단 소속 기업과 독립기업에 대한 R&D 투자의 성과를 비교한 결과, R&D 투자의 성과는 전반적으로 기업가치에 정(+)의 영향을 미치지만 그 긍정적 효과는 독립기업에 비해 대규모기업집단 소속 기업에서 더 저조한 것으로 분석되었다. 이에 대한 원인을 분석하기 위하여 대규모기업집단 소속 기업과 독립기업의 표본을 소속시장과 대주주 지분율에 따라 나누어 분석하였다. 그러한 분석의 결과, 이에 대한 원인은 대규모기업집단 소속 기업의 정보비대칭성보다는 주로 대리인 문제에 기인하는 것으로 여겨졌다. 본 연구의 표본을 소속시장에 따라 나누어 분석해 본 결과, 정보비대칭성의 영향이 일부 관찰되기는 하였으나 이에 대한 증거는 상대적으로 미약한 반면, 대규모기업집단 소속 기업의 표본을 대주주 지분율에 따라 나누어 분석한 결과, 상위지분율 기업보다는 대리인 문제가 더 심각할 것으로 믿어지는 하위지분율 기업에서 R&D 투자가 기업가치에 미치는 긍정적 영향이 훨씬 더 저조하게 나타났다. 그리고 이러한 현상은 연구방법을 변경하거나 대주주의 소유지분율에 따라 대규모기업집단 소속 기업의 표본을 더욱 세분화하였을 때에도 일관성 있게 관찰되었다.

• Journal of Information Technology Applications and Management
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• 제13권3호
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• pp.145-179
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• 2006

The measurement of informatization program effectiveness continues to be a central concern of both academics and practitioners. However, most studies of it have been inclined too heavily toward testing validity and reliability of evaluation measure to strengthen the theoretical rigor. Drawbacks of this approach have been pointed out as being unsuitable for evaluating the effectiveness of informatization program due to lack of practical relevance. The paper comprises four sections to solve the problem. 1) Through literature review of theoretical conceptual models in IS effectiveness and the domestic and foreign cases on informatization program, we establish the evaluation framework which consists of evaluation phases, 6 evaluation areas, and 22 evaluation items, and developed evaluation measures of each items. 2) Different researchers have addressed different aspects of attribute of measure. With comparing them to each other, 3 mutually exclusive criteria on coincidence analysis(usability of measurement. reliability of measurement. and validity of content) are identified. 3) Data are gathered from respondents in informatizaiton program-related organizations such as policy agency, management agency, support agency, and recipient agency. 4) The degree of coincidence of each evaluation measure are analyzed by course of an coincidence analysis procedure, which includes the reliability test, arithmetical test, and criteria validity test. The academic implication of this study is that researchers can gain an insight into the coincidence analysis to approach the problem of deciding on an indicator of performance for informatization program. There is also practical implication for applying the potential means of improving the practical relevance of conducting evaluating the informatization program.

• 산업경영시스템학회지
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• 제12권20호
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• pp.123-138
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• 1989

The primary objective of the agency research in the game theory lives in the maintenance of Pareto is optimal condition for the optimal incentive contract. The basic concepts which are related to this objective are reviewed in connection with the general assumptions to model it, the moral hazard and adverse selection which arised from the information asymmetry, and finally the problem of risk distribution. The demand for auditing and the role of auditor have been addressed by ASOBAC. Issues which an auditor is explicitly introduced in a principal-agent framework have been addressed in this paper. These issues must be confronted to appropriately with the auditor, and to achieve an adequate understanding of optimal confronting arrangement with the auditor. The first step in introducing an auditor into this analysis is to examine the game-theoretic foundation of such a expended agency model. The Mathematical program formulated may not yield solution that are resonable. This arises because the program may call for the auditor and manager to play dominated Nash equilibra in some subgame. The nontrivial natures of the subgame implies that randomized strategies by the auditor and manager nay be of crucial importance. The possibilities for overcoming the randomized strategy problem were suggested; change the rule of the game and or impose covexity condition. The former seems unjustifiable in on auditing context, and the latter promising but difficult to achieve. The discussion ended with an extension of the revelation principle to the owner manager-auditor game, assuming strategies. An examination of the restriction and improvement direction of the basic concept of agency theory was addressed in the later part of this paper. Many important aspects of auditor incentives are inherently multiple-agent, multiple-period, multiple-objectine, phenomena and require further analyses and researches.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.128-141
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• 2015

Independent Component Analysis (ICA), one of the blind source separation methods, can be applied for extracting unknown source signals only from received signals. This is accomplished by finding statistical independence of signal mixtures and has been successfully applied to myriad fields such as medical science, image processing, and numerous others. Nevertheless, there are inherent problems that have been reported when using this technique: instability and invalid ordering of separated signals, particularly when using a conventional ICA technique in vibratory source signal identification of complex structures. In this study, a simple iterative algorithm of the conventional ICA has been proposed to mitigate these problems. The proposed method to extract more stable source signals having valid order includes an iterative and reordering process of extracted mixing matrix to reconstruct finally converged source signals, referring to the magnitudes of correlation coefficients between the intermediately separated signals and the signals measured on or nearby sources. In order to review the problems of the conventional ICA technique and to validate the proposed method, numerical analyses have been carried out for a virtual response model and a 30 m class submarine model. Moreover, in order to investigate applicability of the proposed method to real problem of complex structure, an experiment has been carried out for a scaled submarine mockup. The results show that the proposed method could resolve the inherent problems of a conventional ICA technique.

• 산업공학
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• 제24권4호
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• pp.341-350
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• 2011

This paper considers a problem of locating both distribution centers and retailers in a zone-dependent two-level distribution network where either a distribution center or a retailer should be located in each zone. Customer demands of each zone should be satisfied directly from either its own distribution center or its own retailer being supplied from a distribution center of another zone. The objective of the proposed problem is to minimize total cost being composed of distribution center/retailer setup costs and transportation costs. In the analysis, the problem is proved to be NP-hard, so that a branch-and-bound algorithm is derived for the problem. Numerical experiments show that the proposed branch-and-bound algorithm provides the optimal solution efficiently for some small problems.

• International Journal of Advanced Culture Technology
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• 제7권4호
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• pp.222-228
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• 2019

In recent years, in order to enhance the problem-solving skills required by the industrial field, universities have introduced the Problem-Based Learning(PBL) method to solve the problems caused by the lack of creativity, problem solving ability and self-directed learning. This study applied PBL class methods such as 'learning based on individual specific problems', 'self-directed learning', and 'small-group learning of small members' to practical design of fashion design. To do this, I conducted a questionnaire after conducting research based on the PBL module for one semester in a practical class of fashion design major at P University. As a result of the survey, the satisfaction and achievement of the class conducted by PBL learning method was improved than the existing teaching method. As such, if PBL class is used as a way of solving problems through close communication between professors and learners, it is expected to be established as a learner-centered education method that can improve creativity and professionalism.

• International Journal of Advanced Culture Technology
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• 제8권2호
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• pp.239-245
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• 2020

With the recent revised curriculum, the importance of exploring children's play through new teaching media is increasing in kindergarten. In this study, it is to use the robot 'Bee-bot' for early children to uncover the changes that children have through free exploration and play. As a result of comparing the change of scientific problem-solving ability of 3, 4, and 5-year-olds, there were significant changes in all three sub-elements. We propose to us scientific problem-solving ability test tools, propose and apply ideas for problem-solving, conclusion on problem-solving Building. Through this, it was found that unplugged play using 'Bee-bot' is meaningful as a play environment and as a teaching medium for children aged 3, 4 and 5 years old.

• Journal of Communications and Networks
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• 제18권4호
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• pp.629-638
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• 2016

In this paper, we investigate an energy-efficient resource allocation problem in a two-way relay (TWR) network consisting of multiple user pairs and an amplify-and-forward (AF) relay. As the users and relay have individual energy efficiencies (EE), we formulate a multi-objective optimization problem (MOOP). A single-objective optimization problem (SOOP) of the MOOP is introduced using a weighted-sum method, which achieves a single Pareto optimal point of the MOOP. To derive the algorithm for the SOOP, we propose a more tractable equivalent problem using the Karush-Kuhn-Tucker conditions of the SOOP, which guarantees convergence at the local optimal points. The proposed equivalent problem can be efficiently solved by the proposed iterative algorithm. Numerical results demonstrate the effectiveness of the proposed algorithm in achieving the optimal EE in multi-user AF TWR networks.

• International Journal of Advanced Culture Technology
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• 제7권3호
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• pp.79-85
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• 2019

This study examined the effects of a robotics curriculum based on "Bee-Bot" on the scientific problem-solving ability on 5-year-old children. A robotics curriculum was also designed to enhance their scientific problem-solving ability. This study examined a 4-week robotics curriculum was conducted 12 times for 4 weeks. For this study, 14 children in kindergarten A in Korea were set up as a treatment group and 18 children in kindergarten B in Korea as a control group. It was found that children in the treatment group who engaged in the robotics curriculum using "Bee-Bot" performed better on scientific problem-solving tests. This finding indicates that an enhanced planning experience using "Bee-Bot" was beneficial for improving young children's scientific problem-solving ability. The implications for designing appropriate curricula using "Bee-Bot" robots for kindergarteners are addressed.