• Journal of Korean Elementary Science Education
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• v.19 no.2
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• pp.43-56
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• 2000

Main feature of portfolio assessments is the integration between assessment and instruction. Based on this feature, we developed portfolio assessment regarding feedback fitted into elementary school science classes. The portfolio assessment model is consisted with three steps; the plan of assessment, the practice of portfolio assessment, and the application of assessment result. In the last step, feedbacks of the assessment result were represented to students. From this model, we inspect the possibility of application in elementary school science.

• Management Science and Financial Engineering
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• v.10 no.1
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• pp.25-41
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• 2004

There have been many studies to build a model that can help investors construct optimal portfolio. Most of the previous models, however, are based upon the path-breaking Markowitz model (1959) which is a quantitative model. One of the most important problems with that kind of quantitative model is that, in reality, most of the investors use not only quantitative, but also qualitative information when they select their optimal portfolio. Since collecting both types of information from the markets are time consuming and expensive, making a set of target assets smaller, without suffering heavy loss in the rate of return, would attract investors. To extract only desired assets among all available assets, we need knowledge that identifies investors' preference for the risk of the assets. This study suggests two-layer decision-making rules capable of identifying an investor's risk preference and an architecture applying them to a quantitative portfolio model based on risk and expected return. Our knowledge-based portfolio system is to build an investor's preference-oriented portfolio. The empirical tests using the data from Korean capital markets show the results that our model contributes significantly to the construction of a better portfolio in the perspective of an investor's benefit/cost ratio than that produced by the existing portfolio models.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.3
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• pp.1-21
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• 2016

The Markowitz portfolio selection model uses estimators to deduce input parameters. However, the estimation errors of input parameters negatively influence the performance of portfolios. Therefore, this model cannot be reliably applied to real-world investments. To overcome this problem, we suggest an algorithm that can exclude stocks with large estimation error from the portfolio by applying a tracking signal to the Markowitz portfolio selection model. By calculating the tracking signal of each stock, we can monitor whether unexpected departures occur on the outcomes of the forecasts on rate of returns. Thereafter, unreliable stocks are removed. By using this approach, portfolios can comprise relatively reliable stocks that have comparatively small estimation errors. To evaluate the performance of the proposed approach, a 10-year investment experiment was conducted using historical stock returns data from 6 different stock markets around the world. Performance was assessed and compared by the Markowitz portfolio selection model with additional constraints and other benchmarks such as minimum variance portfolio and the index of each stock market. Results showed that a portfolio using the proposed approach exhibited a better Sharpe ratio and rate of return than other benchmarks.

• Journal of Construction Engineering and Project Management
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• v.1 no.3
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• pp.28-37
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• 2011

Domestic construction companies are suffering from financing difficulties in the wake of the economic slump in Korea and abroad. During this economic slump, real estate investment trusts (REITs), facilitators for improving financing and stimulating construction businesses, have increasingly expanded since their introduction in 2001. However, in terms of growth speed and marketing size, Korean REITs are falling behind those of other nations. The purpose of this study is to suggest a method for composing a portfolio using the Markowitz portfolio selection model to stimulate REITs. The main contents are as follows. First, a comparative analysis was conducted of increased REIT profit with the application of the Markowitz model and the average REIT profit rate from July 3, 2007, to July 21, 2008, during the investment analysis periods. The results showed that the total profit rate from the Markowitz model was about 10% higher than the average REIT profit rate. Second, the sensitivity was analyzed according to the portfolio's data-gathering and replacement cycle to measure the optimum cycle and yield. The six-mouth profit data collection period showed about 16% higher profits with the Markowitz model than with the REITs. The two-week portfolio change period resulted in about 11% higher profits with the Markowitz model than with the REITs.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.37-44
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• 2008

In recent years, e-portfolios and webfolios have been highly vaunted as the next great innovation in education. Hundreds of academic institutions are variously studying, using, or innovating e-portfolio systems. Despite the presumed goodness of e-portfolios, some problems remain. In this paper we review the existing e-portfolio management systems, and propose and implement a novel system to overcome the limits of the existing e-portfolio management systems. The propose e-portfolio management system has a structure of competition with others. All of the student's activities are accomplished and preserved within the same personal web space like a blog with mutual engagements and recommendations.

• Human Ecology Research
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• v.61 no.2
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• pp.195-218
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• 2023

The purpose of this study was to present a class case that verified the validity, reliability, and usefulness of a portfolio assessment in a cohousing class in the housing area of home economics. To achieve this objective, 241 male and female students in eight classes of the third grade of a junior high school in Gyeonggi-do, Korea, were enrolled in a project class on establishing a cohousing village in which the portfolio assessment method was applied for a total of 10 sessions for approximately four weeks from May 24 to June 16, 2021. To ensure the validity of the portfolio assessment, we designed the lesson after presenting the curriculum goals in detail using the backward design model and developed a specific rubric and conducted all evaluations and feedback based on the rubric to ensure objectivity and reliability. The online tool Padlet was used as a portfolio, which allowed students to easily upload their work, receive feedback from the teacher, and interact with their peers. After the class, the students reflected on the rubric and were generally satisfied with the class using portfolio assessment. This study is expected to facilitate the use of the portfolio assessment method in the classroom, while also supporting student growth and development.

• Journal of Digital Contents Society
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• v.14 no.4
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• pp.545-555
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• 2013

Recently student portfolio is widely used as an evaluation method for self-directed performance in engineering education of the university. Especially, as many of the Innovation Centers for Engineering Education and ABEEK held student portfolio competitions, a lot of students in engineering college participate in student portfolio includes the contents and careers of the entire process of university. However, except for courses related to capstone design, there are few regular courses applied to Learning Portfolio in engineering education. Through using Learning Portfolio in courses, students take opportunities of organized collection of learning contents and critical reflection. Under these background study, the regular course in engineering education is may be appropriate for using Learing Portfolio in lecture. In this paper, we present the case study for the Data Structure course opened in the first semester of 2013 which is organized as a Learning Portfolio. According to the results of applying Learning Portfolio to the regular course, it turns out that learners can develope self-directed learning ability in exploring the learning process, and manage a learning process systematically through self-reflection in learning process.

• Journal of Korean Elementary Science Education
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• v.20 no.1
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• pp.107-122
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• 2001

The Purpose of this study is to find the effects of the portfolio assessment on elementary students' scientific knowledge, inquiry process skill, scientific attitudes in the teaching of science. And finally the parents' response to the portfolio assessment is also investigated. In order to reach the goal of this study, the investigator developed the evaluation instrument such as an experimental report and a cumulative observation sheet for the 4th-grade Unit-1 'Light Propagation' and Unit-3 'Separating Mixtures', and then these were administered to 42 4th-grade elementary students in Inchon. Based upon the findings and within the limitations of this study, several conclusions can be drawn regarding the problems investigated. First, as the portfolio assessment offers enough information about individual student's performance, it has a highly positive effect on evaluating the students' scientific knowledges. It can also make possible to grasp the several aspects of the student's progress. Second, the portfolio assessment can be implemented without giving students any psychological pressure from testing itself. Therefore, the portfolio assessment is an effective means of appraising inquiry process skills. Third, the portfolio assessment is effective to evaluate the students' attitude toward science by means of individual records which include such aspects that is hardly found by the teacher who teaches science in the class. Fourth, as most parents showed a positive response to this portfolio assessment, it is considered to be effective method of appraising the result of teaching science at elementary school. Accordingly, this study demonstrated that the portfolio assessment is an effective method that can assess students' scientific knowledges, inquiry process skills, and scientific attitudes gained from science teaching-learning. Therefore, it is necessary to implement the portfolio assessment to other grade students as well in the following study where teacher may give more encouragements and suggestions to sti dents for the better learning motives. Also teachers should suggest more definite evaluation criteria to students so that they may improve the students' self and peer evaluation skills.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.4
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• pp.35-52
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• 2013

Markowitz's portfolio selection model is used to construct an optimal portfolio which has minimum variance, while satisfying a minimum required expected return. The model uses estimators based on analysis of historical data to estimate the returns, standard deviations, and correlation coefficients of individual stocks being considered for investment. However, due to the inaccuracies involved in estimations, the true optimality of a portfolio constructed using the model is questionable. To investigate the effect of estimation inaccuracy on actual portfolio performance, we study the changes in a portfolio's realized return and standard deviation as the accuracy of the estimations for each stock's return, standard deviation, and correlation coefficient is increased. Furthermore, we empirically analyze the portfolio's performance by comparing it with the performance of active mutual funds that are being traded in the Korean stock market and the KOSPI benchmark index, in terms of portfolio returns, standard deviations of returns, and Sharpe ratios. Our results suggest that, among the three input parameters, the accuracy of the estimated returns of individual stocks has the largest effect on performance, while the accuracy of the estimates of the standard deviation of each stock's returns and the correlation coefficient between different stocks have smaller effects. In addition, it is shown that even a small increase in the accuracy of the estimated return of individual stocks improves the portfolio's performance substantially, suggesting that Markowitz's model can be more effectively applied in real-life investments with just an incremental effort to increase estimation accuracy.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.2
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• pp.83-95
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• 2014

In this paper, we develop a portfolio selection model that can be used to invest in markets with margin requirements such as the foreign exchange market. An investment algorithm to implement the proposed portfolio selection model based on objective historical data is also presented. We further conduct empirical analysis on the performance of a hypothetical investment in the foreign exchange market, using the proposed portfolio selection model and investment algorithm. Using 7 currency pairs that recorded the highest trading volume in the foreign exchange market during the most recent 10 years, we compare the performance of 1) the Dollar Index, 2) a 1/N Portfolio which equally allocates capital to all N assets considered for investment, and 3) a hypothetical investment portfolio selected and managed according to the portfolio selection model and investment algorithm proposed in this paper. Performance is compared in terms of accumulated returns and Sharpe ratios for the 10-year period from January 2003 to December 2012. The results show that the hypothetical investment portfolio outperforms both benchmarks, with superior performance especially during the period following financial crisis. Overall, this paper suggests that a mathematical approach for selecting and managing an optimal investment portfolio based on objective data can achieve outstanding performance in the foreign exchange market.