• 한국초등과학교육학회지:초등과학교육
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• 제26권4호
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• pp.372-384
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• 2007

The purposes of this study was to analyze qualitatively changes in students' experience and perceptions in relation to studying science using portfolios and any resultant effects on the portfolio itself. Five fourth-grade elementary students from one small city participated in this study. Data was collected through interviews as well as through student portfolios containing the science content matter of two units over two weeks. Observational diaries recorded by a teacher were also used to test the reliability of data collection. All interviews with students were transcribed to develop a suitable network to categorize students' responses. Students' portfolios were analyzed in order to reveal their essential characteristics in combination with their teacher's observational diaries. The results were as follows. First, student perceptions of their portfolios were categorized into three different levels; superficial, extended, and moderate perceptions. The changes in perception could also be divided into three levels; consistent-superficial, unstable, and a progressive-extended pattern. Second, the experience of students with their portfolio were investigated in terms of the following; successfully completing the elements of the portfolio, development of evidence, interaction with peers, teachers, and parents, and the standards of evaluation used for the portfolios. Third, the perceptions and experience of working on the portfolio by students had a number of direct effects on the way in which students actually created and developed their portfolios. Finally, students with positive attitudes towards their portfolios actively participated in the portfolio experience and finally understood what it meant completely. However, students with negative attitudes regarding portfolio based work, did not leave the experience with any heightened awareness of the utility or indeed, purpose of portfolio based work.

• 한국콘텐츠학회논문지
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• 제13권11호
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• pp.48-58
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• 2013

주식시장은 시간에 따라 계속 변하고 특별한 이유 없이 주가가 급등하거나 급락하는 사건들이 발생하기도 한다. 이런 이유로 주식시장은 복잡계로 인식되고 있으며 주가 변동을 예측하는 것은 어려운 일이다. 이 논문에서는 주식시장을 개별 주식들의 네트워크로 이해하고 시간에 따라 변하는 한국 주식시장 네트워크를 분석하였다. 코스피200 지수를 구성하는 137개 회사의 주식들을 대상으로 주식 사이의 상관관계를 측정한 결과 주식 간 상관관계가 매우 높을 때 주가가 급락하는 경향이 있는 것으로 나타났다. 또한, 우리는 이러한 네트워크 분석 결과를 바탕으로 주식 포트폴리오를 구성하는 방법을 제안한다. 제안 방법으로 구성된 포트폴리오의 효율성을 보이기 위해 실제 주식들을 대상으로 모의 투자 실험을 수행하였고, 마코위츠의 효율적 포트폴리오 구성 알고리즘을 이용해 구성한 포트폴리오의 수익률과 비교하였다. 실험 결과 제안 방법으로 구성된 포트폴리오는 평균적으로 약 10.6%의 수익률을 보였으며, 같은 기간 마코위츠의 효율적 포트폴리오의 수익률보다 약 3.7% 높으며, 코스피200 수익률보다 약 5.6% 정도 높게 나타났다.

• 유통과학연구
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• 제17권9호
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• pp.117-125
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• 2019

Purpose - We investigate how to increase consumer incentives to buy public offering funds, resulting in activating the public offering fund market. In particular, this study aims to find ways to expand diversity and to improve efficiency of public offering fund. The public fund market of Korea has been stagnant in recent years. However, the public offering fund market plays a very significant role in terms of consumer welfare. Since only a few wealthy investors can participate in the private equity market, the stagnation in the public offering fund market usually reduces the opportunity of consumer's buying funds thus ultimately affecting their future wealth. Research design, data, and methodology - To attain our purpose, the 'factor-based portfolio strategy' has been considered. It is an alternative portfolio strategy, which composites the advantages of the passive management and active management. For our empirical anaylsis, we used global stock distribution market data over the period of 1991 and 2016. Then we constructed portfolios based on firm-size, firm-value, and momentum. Finally, a regression model was set, then hypotheses were tested, analyzing the performances. Results - First, among the 15 factor-based portfolios of global, Europe, Asia-Pacific(ex Japan), US and Japan, in eight portfolios, positive excess returns are observed at 5% significance level. Further, there is another portfolio with positive excess return at 10% significance level. Second, most of the portfolios with significant excess performance show positive relationship with the market portfolio. However, the firm-value based portfolio in Asia-Pacific region shows no relationship, and the firm-value based portfolio in US shows negative relationship. Third, we confirmed that the two firm-value factor portfolios in Asia-Pacific region and US, not having positive relationship with market portfolio, provide significant excess returns. Conclusions - In this paper, we provide empirical evidences supporting that the factor-based portfolios expand the diversity of funds and improve the efficiency of investment performance. However, there is no guarantee that the efficiency will continue in the future. In addition, various constraints and costs must be considered. Nevertheless, our novel findings in the advanced financial market such as US and Asia-Pacific are very interesting and offers important implications.

• 한국IT서비스학회지
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• 제17권4호
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• pp.101-117
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• 2018

Companies are responding appropriately to the rapidly changing business environment and striving to lead those changes. As part of that, we are meeting our strategic goals through IT projects, which increase the number of simultaneous projects and the importance of project portfolio management for successful project execution. It also strives for efficient deployment of human resources that have the greatest impact on project portfolio management. In the early stages of project portfolio management, it is very important to establish a reasonable manpower plan and allocate performance personnel. This problem is a problem that can not be solved by linear programming because it is calculated through the standard deviation of the input ratio of professional manpower considering the uniformity of load allocated to the input development manpower and the importance of each project. In this study, genetic algorithm, one of the heuristic methods, was applied to solve this problem. As the objective function, we used the proper input ratio of projects, the input rate of specialist manpower for important projects, and the equal load of workload by manpower. Constraints were not able to input duplicate manpower, Was used as a condition. We also developed a program for efficient application of genetic algorithms and confirmed the execution results. In addition, the parameters of the genetic algorithm were variously changed and repeated test results were selected through the independent sample t test to select optimal parameters, and the improvement effect of about 31.2% was confirmed.

• 산업경영시스템학회지
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• 제32권4호
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• pp.63-71
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• 2009

The traditional portfolio optimization problem is to find an investment plan for securities with reasonable trade-off between the rate of return and the risk. The seminal work in this field is the mean-variance model by Markowitz, which is a quadratic programming problem. Since it is now computationally practical to solve the model, a number of alternative models to overcome this complexity have been proposed. In this paper, among the alternatives, we focus on the Mean Absolute Deviation (MAD) model. More specifically, we developed an algorithm to obtain an optimal portfolio from the MAD model. We showed mathematically that the algorithm can solve the problem to optimality. We tested it using the real data from the Korean Stock Market. The results coincide with our expectation that the method can solve a variety of problems in a reasonable computational time.

• 산업융합연구
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• 제20권2호
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• pp.45-50
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• 2022

본 연구에서는 비대면 교육 환경에서의 질적 개선을 위하여 교수-학습 활동 전반적인 과정을 데이터로 처리하면서 학생들과 소통할 수 있는 e-포트폴리오 시스템을 구성하고 활용하였다. e-포트폴리오는 교수자의 수업 계획부터 성찰의 전 과정을 지원하면서, 수업 운영 과정에서 학습자의 이해도를 정기적으로 확인하고, 온라인상에서 의사소통하며 학습자 중심의 교육 활동을 지원할 수 있도록 구성하였다. 비전공 학생들이 어려워할 수 있는 교양의 프로그래밍 수업에서 e-포트폴리오를 활용한 교수자와 학습자의 의사소통 기반의 학습 효과인 효용성을 분석한 결과, 문제해결력 기반의 과제와 중간고사와 기말고사에서 유의미한 상관이 나타났다. 또한, e-포트폴리오의 만족도를 나타내는 확대 적용성을 분석한 결과, 학생들의 컴퓨팅사고력 검사 결과와 함께 과제, 학업 성적 등과 유의미한 상관이 나타났고, 컴퓨팅사고력의 향상에 유의미한 영향을 주는 것으로 나타났다. 제안하는 e-포트폴리오 시스템 형태를 활용하여 비대면 교육을 실시한다면, 학생들과 효율적으로 소통하면서 비대면 교육의 품질을 향상시킬 수 있을 것이다.

• 품질경영학회지
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• 제41권4호
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• pp.637-648
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• 2013

Purpose: The objective of this study is to provide a methodology that can facilitate efficient development of a product portfolio by utilizing Korean Standards(KS) networks. Methods: A case study on a steel manufacturing company is provided. Social network analysis h as been conducted on KS network and KS certification information of the company. Core test standards of a company have been identified. The core standards, then, used to construct a product-standard network of a corresponding industry. Results: As a result of analyzing product-standard networks, a product portfolio of a company has been developed. It has been shown that the candidate product portfolio is a cost-effective alternative in terms of standard maintenance cost. Conclusion: By using social network analysis, standards information can be used to support new product development process.

• 산업공학
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• 제23권4호
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• pp.300-310
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• 2010

This paper is about an optimal investment portfolio strategy. Financial data of stocks, bonds, and savings from January 2. 2001 through October 30. 2009 were utilized in order to suggest the optimal portfolio strategies. Fundamental analysis and technical analysis were used in stocks-related strategy, whereas passive investment strategy and active investment strategy were used in bond-related strategy. The score is assigned to each stock index according to the suggested strategies and set trading rules are based on the scores. The simulation has been executed about each 29,400-portfolios and we figured out with the simulation result that 26.75% of 7,864 portfolios are more profitable than average stock market profit (22.6%, Annualized). The outcome of this research is summarized in two parts. First, it's the rebalancing strategy of portfolio. The result shows that value-oriented investment(long-term investment) strategy yields much higher than short-term investment strategies of stocks or active investment of bonds. Second, it's about the rebalancing cycle forming the portfolios. The result shows that the rate of return for the portfolio is the best when rebalancing cycle is 12 or 18 months.

• 응용통계연구
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• 제34권1호
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• pp.39-56
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• 2021

Markowitz (1952)의 분산투자 모형 발표 이후 포트폴리오 최적화에 대한 많은 연구가 이루어졌다. 마코위츠의 평균-분산 포트폴리오 최적화 모형은 수익 분포가 정규분포를 따른다는 가정하에서 성립한다. 그러나 실생활에서는 수익 분포가 정규분포를 따르지 않는 경우가 존재한다. 또한 분산은 이상치의 영향을 많이 받는 민감한 지표이다. 이런 분산의 단점을 보완할 수 있는 하방위험인 숏폴(Shortfall)을 위험 지표로 적용함으로써 수익 분포에 대해 최적화가 가능한 평균-숏폴 포트폴리오 모형이 제안되었다. 또한 Jorion (2003)과 Park(2019)은 포트폴리오의 위험도를 최소화하는 동시에 적은 수의 자산으로 구성(sparse)되고 안정적(stable)인 포트폴리오를 얻는 퍼터베이션 방법을 제안하였다. 본 논문에서는 평균-숏폴 포트폴리오 모형에 퍼터베이션 방법과 adaptive Lasso를 적용하여 사용되는 자산의 수가 적으면서 안정적이고 쉽게 적용 가능한 포트폴리오 모형을 제안한다. 그리고 실증 데이터 분석을 통하여 모형의 타당성을 입증한다.

• Agribusiness and Information Management
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• 제8권2호
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• pp.9-15
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• 2016

In several industries, including the agriculture industry, information and communication technology (ICT) expenditure has been gradually increasing. This study explores the ICT investment of Korean agricultural corporations, and examines the effect of ICT investment on their profitability using an IT portfolio framework. As the organizational capabilities and environment in which ICT is used is critical in examining its impact, the IT-savvy level is used as a moderator. An increase in ICT investment size results in a significantly positive effect on profitability in organizations with higher IT-savvy levels, whereas there is no effect in organizations with lower IT-savvy levels. This study shows the necessity of understanding the structure of ICT investments in the agriculture industry, and suggests the importance of organizational capabilities and environment in making best use of ICT.