• School Mathematics
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• v.10 no.4
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• pp.557-571
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• 2008

The objective of this paper is to study De Morgan's thoughts on teaching and learning negative numbers. We studied De Morgan's point of view on negative numbers, and analyzed his didactical approaches for negative numbers. De Morgan make students explore impossible subtractions, investigate the rule of the impossible subtractions, and construct the signification of the impossible subtractions in succession. In De Morgan' approach, teaching and learning negative numbers are connected with that of linear equations, the signs of impossible subtractions are used, and the concept of negative numbers is developed gradually following the historic genesis of negative numbers. Also, we analyzed the strengths and weaknesses of the De Morgan's approaches compared with the mathematics curriculum.

• The Journal of the Korea Contents Association
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• v.15 no.10
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• pp.46-55
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• 2015

This study is to re-read Yun, Baek-nam(1888-1954)'s editorial "Theatre and Society" from the perspective of postcolonial criticism. He was a man of the theatre who pursued practical interests in compliance with the colonial reality under the rule of the Japanese imperialism. His advocacy of theatre development work was based on the Japan-directional reformism and on Japan-friendly in following after Japan's improvement policy. His general discussion on Western theatre history had considerable errors as a result of focus on the social role and utility of the theatre. But his vindication of theatre-actor opened an era of interaction between theatre and intelligence in Korea. In addition, his enlightening view of a theatre became such as one of the cornerstones for the Shinkug Movement during Japanese colonial period in Korea.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.2
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• pp.75-93
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• 2013

In applying Markowitz's portfolio selection model to the stock market, we developed a comprehensive investment decision-making framework including key inputs for portfolio theory (i.e., individual stocks' expected rate of return and covariance) and minimum required expected return. For estimating the key inputs of our decision-making framework, we utilized an exponentially weighted moving average (EWMA) which places more emphasis on recent data than the conventional simple moving average (SMA). We empirically analyzed the investment results of the decision-making framework with the same 15 stocks in Samsung Group Funds found in the Korean stock market between 2007 and 2011. This five-year investment horizon is marked by global financial crises including the U.S. subprime mortgage crisis, the collapse of Lehman Brothers, and the European sovereign-debt crisis. We measure portfolio performance in terms of rate of return, standard deviation of returns, and Sharpe ratio. Results are compared with the following benchmarks : 1) KOSPI, 2) Samsung Group Funds, 3) Talmudic portfolio based on the na$\ddot{i}$ve 1/N rule, and 4) Markowitz's model with SMA. We performed sensitivity analyses on all the input parameters that are necessary for designing an investment decision-making framework : smoothing constant for EWMA, minimum required expected return for the portfolio, and portfolio rebalancing period. In conclusion, appropriate use of the comprehensive investment decision-making framework based on the Markowitz's model integrated with EWMA proves to achieve outstanding performance compared to the benchmarks.

• Bulletin of the Korean Mathematical Society
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• v.25 no.2
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• pp.203-209
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• 1988

In this paper, we define a g-regular semigroup which is a generalization of a regular semigroup. And we want to find some properties of g-regular semigroup. G-regular semigroups contains the variety of all regular semigroup and the variety of all periodic semigroup. If a is an element of a semigroup S, the smallest left ideal containing a is Sa.cup.{a}, which we may conveniently write as $S^{I}$a, and which we shall call the principal left ideal generated by a. An equivalence relation l on S is then defined by the rule alb if and only if a and b generate the same principal left ideal, i.e. if and only if $S^{I}$a= $S^{I}$b. Similarly, we can define the relation R. The equivalence relation D is R.L and the principal two sided ideal generated by an element a of S is $S^{1}$a $S^{1}$. We write aqb if $S^{1}$a $S^{1}$= $S^{1}$b $S^{1}$, i.e. if there exist x,y,u,v in $S^{1}$ for which xay=b, ubv=a. It is immediate that D.contnd.q. A semigroup S is called periodic if all its elements are of finite order. A finite semigroup is necessarily periodic semigroup. It is well known that in a periodic semigroup, D=q. An element a of a semigroup S is called regular if there exists x in S such that axa=a. The semigroup S is called regular if all its elements are regular. The following is the property of D-classes of regular semigroup.group.

• Journal of the Daesoon Academy of Sciences
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• v.22
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• pp.471-507
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• 2014

Edification in Daesoonjinrihoe is not only a phenomenon that occurs following the differences of religious experience or spiritual development among the community members, which enables the members to share teaching and learning experiences with one another, but also an issue determined as one of the major activities of the religious order and a plan for achieving the purpose of the religious order-Podeokchenha(Wordly Propagation), Gujechansaeng (Salvation of all mankind) and Jisangcheonguk Geonseol(Building of earthly paradise). The purpose of this article is to clarify its concept and provide an example of edification, through considering the historical model for edification to help the cultivators with their work of edification. The archetype of edification of Daesoonjinrihoe was formed and gradually developed in phases by Sangje, Kang Jeungsan, the Supreme God(姜甑山, 1871-1909), Doju, Jo Jeongsan(趙鼎山, 1895-1958) and Dojeon, Park Wudang(朴牛堂, 1917-1995), by the three of whom the Religious Authority was succeeded. Sangje descended to the human world and preached to people to live by the rule of Haewon Sangsaeng(Resolution of grievances for the mutual beneficences of all life) and set an example of abolishing the old customs, living in mutual beneficences and having respect for human being. Doju, in revering the last will of Sangje, established the religious order by setting its creed, rituals and activities, which formed most contents of the archetype of edification. Dojeon set up a religious faith system by firmly establishing the Religious Authority and performed the True Law in accordance with Sangje's program of heaven to educate the cultivators to achieve the goal of self-cultivation following the last will of Doju. Through this, a perfect method to reach the state of Dotong(The Truly Unified State of Dao) is fulfilled. In this way, the archetype of edification was formed in the process of succession of Religious Authority. In conclusion, edification in Daesoonjinrihoe contributes to a 'systematic conveyance and understanding' through the historical archetype of edification, and it can be described as a concept that becomes a model to put into practice the 'True Law' of teachings given by two Sangjes for Dotong. Therefore, edification of Daesoonjinrihoe is drawing attention of its development as an important activity that realizes the ultimate value of the religious order because it solves the problems of immorality(absence of Dao), disorder and disregard of human value generated from the other side of this material civilization, with the truth of Haewon Sangsaeng, and has a function of rebuilding and leading the individuals and the society to the Truly Unified State of Dao through performing of the True Law.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.1
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• pp.33-38
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• 2011

Now a days, there's many change over for PACS among the most of hospital and it standard for DICOM 3.0. These kind of using of DICOM 3.0 improves increasing of medical imaging exchange and service for patient. However, there's some problems of compatibility caused during carry out CD and DVD from hospital. For this reason, this thesis analyzed patients image targeting those storages requested to hospitals in Seoul by using Validation Toolkit which is recommended from KFDA. The analyze type is like this. Make 100 data, total 500, each of MRI CT Plain x-ray Ultrasound PET-CT images and analyzed type of error occurred and loyalty of information. If express percentage of error occurred statistically, we can get a result as follows MRI 5%, Plain x-ray 11%, CT 18%, US 25%, PET-CT 30%. The reson why percentage of error occurred in PET-CT is because of imperfective support and we could notice that we weren't devoted to information. Even though, PET-CT showed highest percentage of error occurred, currently DICOM data improved a lot compare to past. Moreover, it should be devoted to rule of IHE TOOL or DICOM. In conclusion, we can help radiographer to analyze information of image by providing clues for solving primary problem and further more, each of PACS company or equipment company can enhance fidelity for following standard of image information through realizing the actual problem during transfer of image information.

• Journal of the Korean Society of Earth Science Education
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• v.8 no.3
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• pp.346-354
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• 2015

The purpose of this study was to be a help with designing science curriculum and developing science programs for the science gifted students by comparing their preferences about science class forms and class environments between science gifted students and normal students. For this study, 2 classes of science gifted students and 5 classes of normal students in 4th, 5th grade joined in this survey and their preferences about science class forms and class environments were checked using questionnaire. As a result, the following findings were obtained. First, in the area of class form, from comparing their preferences about teaching content domain, science gifted students showed meaningful higher preferences in all factors such as clarification, structuralization, thinking of high level and diversification. In comparing their preferences about teaching process domain, science gifted students also showed meaningful higher preferences in all factors such as diversification and self directed learning. Second, in the area of class environment, from comparing their preferences about classroom domain, science gifted students showed meaningful higher preferences in all factors such as teacher's support and rule and organization. In comparing their preferences about mentality domain, science gifted students also showed meaningful higher preferences in all factors such as influence of friends and parents. Third, in science gifted students, from comparing their preferences by gender about science class forms and class environments, female students showed meaningful higher preferences in factors of clarification. And in other factors females showed similar preference tendency with male students. In normal students' comparing, female students showed meaningful higher preferences in factors of teacher's support. And male students showed meaningful higher preferences in factors of high level thinking and influence of friend and influence of parents.

• Journal of Korean Society of Rural Planning
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• v.11 no.2 s.27
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• pp.51-57
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• 2005

It has been well known that soil erosion and sediments from alpine agricultural fields are causing severe water quality and turbidity problems in receiving waters. Also these result in the loss of money because farmers have to buy top soils to provide enough root zone in the following year. Thus, there have been needs to reduce soil erosion and sediment discharge into the stream networks. To accomplish this end, an effective erosion control plans should be developed based on scientific research, not by rule of thumb. The Universal Soil Loss Equation (USLE) has been widely used to estimate the soil erosion in many countries over the years. In this study, the USLE was used to estimate soil erosion potential under different cropping scenarios in HongCheon County, Kangwon. The soil erosion potential for continuous corn cropping was the highest compared with those from continuous potato find average cropping scenarios. This indicates the soil erosion plans need to be established considering cropping system in the field. The Unit Stream Power Erosion-Deposition (USPED) was applied for HongCheon County to estimate soil erosion and deposition areas. The USPED estimated results can be used to complement USLE results in developing effective erosion control plans.

• Journal of Korea Multimedia Society
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• v.7 no.2
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• pp.145-155
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• 2004

It is very important for Internet searching systems to have user-friendly and rapid searching functions at the managers'point of view. The former finds optimized input parameters to support the various searching requirements of user. The latter has fast searching results which are effectively normalized to various input parameters having different attributes. In this paper we basically focus on optimized database construction not only to have searching functions with multiple attributes to support maximal various input requirements of the user but also to have more rapid searching functions. For this research, we suggest a modified association algorithm that takes into consideration to the support and confidence that is the criteria of the association mining rule in order to reflect the searching characteristics of internet shopping malls. We also propose the model management systems for rapid searching functions. The following results are from a processed simulation: the more the number of searching transactions of the users increase, the less the total relative average searching time becomes.

• Journal of The Korean Association For Science Education
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• v.13 no.3
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• pp.389-395
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• 1993

Science textbooks which were compiled by CHOSUN Government General are known as books which appeared after 'Science Textbook for Common School' (1923-) compiled by CHOSUN Government General which are almost similar to state authorized textbooks and are also known as leaving the effect on 'Science Textbook for Elementary School' (1931-) which were focused on the subjects being issued since then and 'Science Text for Elementary Course' (1942-) being compiled by the Education Ministry, However in this research it was found out that there were publications in 1911, 1913 and 1921 and they were harbingers for 'Science Textbook for Elementary School' 0931-). For this reason it was decided to report overall picture on the science textbooks being compiled by CHOSUN Government General. And it was possible to illustrate that such textbooks can be classified into following 5 periods ; The 1st period:The time for search--'Science Textbook for Students of Common school' 1911 compiled by CHOSUN Government General. The 2nd period:Commencing separate compilation--'Science Textbook for Common School' 1913 compiled by CHOSUN Government General. (The 2'nd period:Final Separate Compilation-- Reissue after corrections of 'Science Textbook for Common School' compiled by CHOSUN Government General, 1921.) The 3rd period:Same as the state authorized science textbook of Japan--' Science Textbook for Common School' compiled by CHOSUN Government General, totally 3 books 1923-. The 4th period:Separate compilation, centered on subjects--'Science Textbook for Elementary School' compiled by CHOSUN Government General, 1931-. (The 4'th period:Changers of subjects--'Science Text for Elementary School' compiled by CHOSUN Government General, 1937-. The 5th period:Matched to compiled by the Education Ministry--'Observation of Nature' compiled by CHOSUN Government General, 1942-'Science Text for Elementary School'(Writing laterally) 1943-.