• Journal of the military operations research society of Korea
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• v.34 no.3
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• pp.107-116
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• 2008

This paper deals with modelling and introducing of the project portfolio construction and evaluation problem under uncertainty. The common way in industry of managing project portfolio is construction of initial portfolio considering uncertainties which exist inside and outside of portfolio, and periodic revision of portfolio due to the deviation from plans. In this paper, we introduce algorithm which reflecting the industrial common practice of initial planning and periodic revision. With this simulation method, probabilistic distribution of portfolio's performance in consideration can be found.

• IE interfaces
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• v.20 no.2
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• pp.94-102
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• 2007

Portfolio management deals with decision making on 'when' and 'how' to revise an existing portfolio. In this paper, we show that a classical statistical process control (SPC) chart for normal data, a wellestablished tool in quality engineering, can effectively be used for signaling times for revising a portfolio. Noting that the day-to-day performance of a portfolio may be auto-correlated, we use the exponentially weighted moving average center-line chart to develop an automatic portfolio management procedure. The portfolio management procedure is extensively tested on historical data of equities traded in the Korea Exchange (KRX), the American Stock Exchange (AMEX), and the New York Stock Exchange (NYSE). In comparison with the performances of the KOSPI, XAX, and NYA indices during the same time periods, results from these experiments show that SPC chart-based portfolio revision presents itself a convenient and reliable method for optimally managing portfolios.

• IE interfaces
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• v.25 no.2
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• pp.163-169
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• 2012

This paper proposes an efficient portfolio management methodology named sSPPM with consideration of risk and required return. sSPPM employs Markowitz's portfolio model to select securities and adopts ($s$, $S$) policy that is a well-known technique in the inventory control area to revise the current portfolio. Computational experiments using virtual stock prices generated by monte carlo simulation method as well as real stock ones of KOSPI for recent 4 years are conducted to show the excellence of the portfolio management under ($s$, $S$) policy framework. The result shows that sSPPM is remarkably superior to both 6 or 12 months based periodic portfolio revision method and market (KOSPI index).

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.10-10
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• 2003

Option pricing theory developed by Black and Sholes depends on an arbitrage opportunity argument. An investor can exactly replicate the returns to any option on that stock by continuously adjusting a portfolio consisting of a stock and a riskless bond. The value of the option equal the value of the replicating portfolio. However, transactions costs invalidate the Black-Sholes arbitrage argument for option pricing, since continuous revision implies infinite trading, Discrete revision using Black-Sholes deltas generates errors which are correlated with the market, and do not approach zero with more frequent revision when transactions costs are included. Stochastic calculus serves as a fundamental tool in the mathematical finance. We closely look at the utility maximization theory which is one of the main option valuation methods. We also see that how the stochastic optimal control problems and their solution methods are applied to the theory.

• Journal of Korean Elementary Science Education
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• v.17 no.1
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• pp.11-21
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• 1998

Portfolio assessment provides many opportunities to foster children's creativity and to increase their responsibility for learning. few research study has been conducted in this area, and this assessment method has scarcely been administered in primary science class, Proper and effective use of portfolio assessment in our primary science class requires basic research on how to design and administer the method. Based on the earlier study on typical structures and components of portfolio assessment, the assessment instrument was developed on various primary science topics, The development team was consisted of one science education specialist and nine pre-service elementary school teachers. It takes ten months to develop instruments for 27 class hours. The development process was reciprocal in that development and revision cycle was repeated more than 7 times. The portfolio assessment instruments consist of instructional objectives, developers' evidence for the objectives, and assessment criteria. Adopting a new way of assessment into science class inevitably causes lots of confusions to teachers and children. The absence of basic research studies must be a critical barrier for successful administration of a new assessment method such as portfolio assessment. further research is required in the preparation and administration of portfolio assessment in our primary science classroom.

• Fashion, Industry and Education
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• v.14 no.2
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• pp.60-69
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• 2016

Visual literacy, a key element of a design portfolio, is achieved by communicating a consistent visual aesthetic with respect to design elements, design principles and individual style. Yet, students often feel challenged in articulating their personal aesthetic or design philosophy in order to create a unifying design identity within a body of artifacts. This paper shares some best practices on overcoming this challenge through students' engagement in self-reflection and identity formation processes. The implemented innovative strategy in a senior-level portfolio development course for apparel designers involved four different phases: 1) one-on-one meetings to self-reflect on previous design work, 2) selection and revision of artifacts, 3) peer-review and critiques of revised portfolio artifacts, and 4) development of a final ePortfolio to showcase a unified design identity. It was evident that recording students' initial self-reflection in the form of a metacognitive oral report encouraged and motivated identity development in their portfolio. Further, students expressed their satisfaction in the ability to participate in the selection process of artifacts by self-reflecting about what they wanted to highlight about themselves and why. Overall, student outcomes from this strategy exceeded expectations and the portfolios developed were successful in creating a cohesive design identity.

• English Language & Literature Teaching
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• v.9 no.2
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• pp.17-33
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• 2003

College going students who are non-native speakers of English enrolled in English language programmes are not acquiring the needed academic writing skills. Many of these students do not have positive attitudes towards writing, thus forcing language instructors to look for ways of motivating students to write in order to improve writing skills. This action research project investigates the use of portfolio writing to improve writing ability among pre-university students. Research on the use of portfolio writing suggests that it is a useful way for developing interest in writing and for developing effective writing skills over a period of time. Portfolios support the best thinking in composition pedagogy in that it encourages process writing. Although the portfolio is considered a writing product, as a whole it is evidence of the students writing process. An important feature in using portfolios is that students are able to focus on their writing without constantly worrying about grades. Instructors have noticed that students make greater improvement in their writing when their focus is shifted from punitive feedback through letter grades to constructive feedback in the form of suggestions for further revision. This paper describes the use of writing portfolios as an effective means of teaching writing. The findings revealed that writing portfolios helped develop confidence in writing and decreased anxiety towards writing. (217 words)

• Journal of the Korea Convergence Society
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• v.12 no.6
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• pp.139-150
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• 2021

Currently, the RPS(Renewable Portfolio Standard) is the policy which supplies new and renewable energy. Power generation companies with large capacity should produce renewable energy or secure through the purchase of REC (Renewable Energy Certificates) as mandatory. The government has revised the REC weight several times, which weights each energy source by evaluating the economic and social value of renewable energy sources, and revised the mandatory supply ratio to gradually increase. This study helps to find the impact of policies on related industries. In this study, time-series analysis and regression analysis on the capacity of PV(Photovoltaics) facilities as a dependent variable were performed to analyze the effect of the revision of the REC weight for photovoltaic power generation and the amount of mandatory supply for renewable energy. As a result, it was statistically assessed that the revision of the REC weight and the increase in the mandatory supply has a significant effect on the increase in the amount of PV facilities.

• 대한공업교육학회지
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• v.43 no.1
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• pp.94-113
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• 2018

The purpose of this study is to develop a using various convex lenses 'VR glasses' instructional materials for area of communication technology of the 2015 Revision Curriculum in middle school. This study was progressed depend on ADDIE model. In the analysis step, a necessity of developing the instructional materials was confirmed through social needs and leaner's needs and literature researches were reviewed about the 2015 Revision Curriculum and virtual reality and confirmed the area of communication technology related to VR glasses. The communication process of information was selected as a communication technology area related to VR glass. In the design step, Based on the analysis stage, instructional objectives were set and instructional method and medium were selected. In the development step was developed instructional materials, what are teaching-learning guidance, power-point presentations, the paper for group learning activities, Individual portfolio, and using various convex lenses VR glasses example. As a result of 'VR glasses' using various convex lenses, the viewing angle was enlarged when the diameter of the convex lens was large, but it was difficult to quantify it. In the implementation step, the instructional materials developed for middle school students was applied. In the evaluation step, instructional materials were modified and improved through a students evaluation, experts evaluation.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.525-529
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• 2016

Biomass co-firing to existing thermal power plants is one of the most economical and efficient way to reduce $CO_2$ emission from the plant. There are several methods of co-firing and it can be categorized into (1) Parallel co-firing, (2) Indirect co-firing, and (3) Direct co-firing. Parallel co-firing is the most expensive way to high-ratio co-firing because it requires biomass dedicated boiler. Direct co-firing is widely used because it does not need high capital cost compared with the other two methods. Regarding the direct co-firing, it can be classified into three methods- Method 1 does not need retrofit of the facilities because it uses existing coal mills for pulverizing biomass fuels. In this case high-ratio co-firing cannot be achieved because of poor grindability of biomass fuels. Method 2 needs biomass-dedicated mills and revision of fuel streams for the combustion system, and Method 3 needs additional retrofit of the boiler as well as biomass mills. It can achieve highest share of the biomass co-firing compared with other two methods. In Korea, many coal power plants have been adopting Method 1 for coping with RPS(Renewable portfolio standards). Higher co-firing ratio (> 5% thermal share) has not been considered in Korean power plants due to policy of limitation in biomass co-firing for securing REC(Renewable Energy Certificate). On the other hand, higher-share co-firing of biomass is widely used in Europe and US using biomass dedicated mills, following their policy to enhance utilization of renewable energy in those countries. Technical problems which can be caused by increasing share of the biomass in coal power plants are summarized and discussed in this report. $CO_2$ abatement will become more and more critical issues for coal power plants since Paris agreement(2015) and demand of higher share of biomass in the coal power plants will be rapidly increased in Korea as well. Torrefaction of the biomass can be one of the best options because torrefied biomass has higher heating value and grindability than other biomass fuels. Perspective of the biomass torrefaction for co-firing is discussed, and economic feasibility of biomass torrefaction will be crucial for implementation of this technology.