• Journal of Korean Elementary Science Education
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• v.24 no.3
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• pp.301-309
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• 2005

The purpose of this study was to investigate the measuring range of portfolio assessment on students' abilities, using correlation coefficients of portfolio assessment with four other assessment methods. A portfolio system was developed based on low units of elementary fourth grade science, and applied to three fourth-grade science classes in Daejeon Metropolitan area and Gyunggi-do. Four different assessment methods, multiple-choice (short answer type), essay-type item, mind-mapping and laboratory assessment were also administered and scored by two elementary teachers attending graduate school. Correlation coefficients between portfolio assessment and four assessment methods were calculated with SPSS. Portfolio assessment showed moderate correlation with multiplechoice (short answer), essay-type, and mind-mapping, and low correlation with laboratory assessment. Portfolio assessment showed high correlation with multiple-choice assessment in 'understanding' and 'application' domains, but showed low correlation in 'recall' and 'inquiry' domains. In conclusion, portfolio assessment could measure various abilities measured by other assessment methods.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.17 no.2
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• pp.115-128
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• 2013

The optimal portfolio selection problem under inflation risk and subsistence constraints is considered. There are index bonds to invest in financial market and it helps to hedge the inflation risk. By applying the martingale method, the optimal consumption rate and the optimal portfolios are obtained explicitly. Furthermore, the quantitative effect of inflation risk and subsistence constraints on the optimal polices are also described.

• Journal of the Chungcheong Mathematical Society
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• v.29 no.2
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• pp.329-336
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• 2016

The optimal portfolio choice problem with a stochastic income is considered in continuous-time framework. We provide a novel approach to treat the stochastic income when the market is complete. The developed method is useful to obtain closed-form solutions of the problems under borrowing constraints.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.2
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• pp.293-300
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• 2020

In this paper we study an optimal consumption, investment and retirement time choice problem of an investor who receives labor income before her voluntary retirement. And we assume that there is a negative wealth constraint which is a general version of borrowing constraint. Using convex-duality method, we provide the closed-form solutions of the optimization problem.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.1
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• pp.103-112
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• 2020

This paper investigates the portfolio selection problem with flexible labor choice and stochastic income flow where the unit wage flow is governed by a stochastic process. The agent optimally chooses consumption, investment, and labor supply. We derive the closed-form solution by applying a martingale method even with the stochastic income flow.

• Bulletin of the Korean Mathematical Society
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• v.60 no.4
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• pp.1101-1129
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• 2023

In this study we propose a model of optimal retirement, consumption and portfolio choice of an individual agent, which encompasses a large class of the models in the literature, and provide a methodology to solve the model. Different from the traditional approach, we consider the problems before and after retirement simultaneously and identify the difference in the dual value functions as the utility value of lifetime labor. The utility value has an option nature, namely, it is the maximized value of choosing the retirement time optimally and we discover it by solving a variational inequality. Then, we discover the dual value functions by using the utility value. We discover the value function and optimal policies by establishing a duality between the value function and the dual value function. The model and approach offer a significant advantage for computation of optimal policies for a large class of problems.

• Journal of Information Processing Systems
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• v.18 no.5
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• pp.637-649
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• 2022

Investors aim to increase their profitability by investing in the stock market. An adroit strategy for minimizing related risk lies through diversifying portfolio operationalization. In this paper, we propose a six-step stocks portfolio selection model. This model is based on data mining clustering techniques that reflect the ensuing impact of the political, economic, legal, and corporate governance in Mongolia. As a dataset, we have selected stock exchange trading price, financial statements, and operational reports of top-20 highly capitalized stocks that were traded at the Mongolian Stock Exchange from 2013 to 2017. In order to cluster the stock returns and risks, we have used k-means clustering techniques. We have combined both k-means clustering with Markowitz's portfolio theory to create an optimal and efficient portfolio. We constructed an efficient frontier, creating 15 portfolios, and computed the weight of stocks in each portfolio. From these portfolio options, the investor is given a choice to choose any one option.

• Journal of the Korean Statistical Society
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• v.3 no.1
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• pp.31-57
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• 1974

The economic behavior of individuals' selection of particular kye and positions in a kye is based upon choice criteria. The selection of a kye or a position in a kye is not the same as an investor's portfolio selection. A kye member combines in varying degrees the characteristics of both a borrower and a lender of funds. In the following sections we shall first propose choice criteria for borrowers and lenders of funds, then we will try to test various hypotheses derived from the choice criteria by empirical data.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.2
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• pp.343-349
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• 2013

The optimal portfolio selection problem under inflation risk is considered in this paper. There are three assets the economic agent can invest, which are a risk free bond, an index bond and a risky asset. By applying the martingale method, the optimal consumption rate and the optimal portfolios for each asset are obtained explicitly.

• East Asian Economic Review
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• v.25 no.4
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• pp.339-360
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• 2021

More donors are formally assessing their multilateral aid disbursement policies as well as the multilateral institutions that they contribute to. Analyzing OECD Creditor Reporting System data from 2011 to 2019 of 23 donors and 34 multilateral organizations, we find evidence of institutional portfolio building of donors to align multilateral and bilateral aid channels. Such tendency is more pronounced for core-funding than multi-bi funding and much stronger at the recipient country level than at the sectoral level. Smaller donors that operate from a limited multilateral budget show greater preferences for geographical similarity. When donors give to institutions with sectoral specialization, they seek sectoral similarity with their bilateral aid.