• Communications for Statistical Applications and Methods
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• v.15 no.1
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• pp.117-124
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• 2008

The liquidity risk is defined as an additional risk in the market due to the timing and size of a trade. A recent work by Cetin et ai. (2003) proposes a rigorous mathematical model incorporating this liquidity risk into the arbitrage pricing theory. A practical problem arising in a real market application is an estimation problem of a liquidity cost. In this paper, we propose to estimate the liquidity cost function in the context of Cetin et al. (2003) using the constrained least square (LS) method, and illustrate it by analyzing the Kellogg company data.

• Bulletin of the Korean Mathematical Society
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• v.50 no.2
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• pp.353-373
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• 2013

In this paper, a class of delayed predator-prey models of prey migration and predator switching is considered. By analyzing the associated characteristic transcendental equation, its linear stability is investigated and Hopf bifurcation is demonstrated. Some explicit formulae for determining the stability and the direction of the Hopf bifurcation periodic solutions bifurcating from Hopf bifurcations are obtained by using the normal form theory and center manifold theory. Some numerical simulations for justifying the theoretical analysis are also provided. Finally, biological explanations and main conclusions are given.

• Communications for Statistical Applications and Methods
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• v.12 no.1
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• pp.217-227
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• 2005

The data mining is a new approach to extract useful information through effective analysis of huge data in numerous fields. We utilized this data mining technique to analyze medical record of 35,671 people. Whole data were assorted by BMI score and divided into two groups. We tried to find out BMI risk factor from overweight group by analyzing the raw data with data mining approach. The result extracted by C5.0 decision tree method showed that important risk factors for BMI score are triglyceride, gender, age and HDL cholesterol. Odds ratio of major risk factors were calculated to show individual effect of each factors.

• East Asian mathematical journal
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• v.28 no.2
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• pp.173-195
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• 2012

The purpose of this study is to help for an in-depth understanding of their thinking process by observing and analyzing the response found by two elementary school students, Through this study, the following findings could be obtained. First, two students have a tendency trying to solve the complex situation at first. Second, we could know that it is an important factor in discovering the pattern to predict it. Third, we could know that the activity of reconstructing the data meaningfully is an important factor in discovering the pattern. Fourth, it is an important factor in finding the pattern to work organically the activity of predicting it with the activity of reconstructing the data meaningfully. We hope that this study offers the help for an in-depth understanding of students's thinking process.

• Communications of Mathematical Education
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• v.26 no.2
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• pp.155-176
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• 2012

In this paper, we present a practical and essential method of using team projects for calculus. We, specifically, take into account the team project that calculate the volume of lung represented on CT scan images. We have demonstrated that the process of analyzing the images in a team project encourage studying numerical methods of integration for calculus. Also, we have used various technological programs(MATLAB, MATHEMATICA, MS Excel) to solve the team project.

• East Asian mathematical journal
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• v.23 no.3
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• pp.271-302
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• 2007

The purpose of this study is to study how effective teachers' self reflectiveness are on enhancing mathematics teaching activities. Researcher is the object of the study and relating preceding researches, establish some instruments for study. This research was examined for six times from fifth week of March to second week of May. In order to accomplish this study, one class of the first grade of high school in Ulsan was selected. In order to define the changes of teaching activity, the first lecture was practiced without analyzing or reflective activity. From the second lecture, analyze and reflect own teaching activity with recording. After finishing all lecture, distribute the recordings to observers and other teachers and then, get measured. Based on the results, self reflective teaching makes great effects on enhancing teachers' teaching activities. Through teachers' own reflective teaching, they can know their advantages and disadvantages, repeatable was of speaking, and the acknowledgement of objectives. And, finally, they can enhance their teaching activity by reflective teaching.

• Communications for Statistical Applications and Methods
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• v.27 no.5
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• pp.569-578
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• 2020

Various graph clustering methods have been introduced to identify communities in social or biological networks. This paper studies the entropy-based and the Markov chain-based methods in clustering the undirected graph. We examine the performance of two clustering methods with conventional methods based on quality measures of clustering. For the real applications, we collect the mathematical subject classification (MSC) codes of research papers from published mathematical databases and construct the weighted code-to-document matrix for applying graph clustering methods. We pursue to group MSC codes into the same cluster if the corresponding MSC codes appear in many papers simultaneously. We compare the MSC clustering results based on the several assessment measures and conclude that the Markov chain-based method is suitable for clustering the MSC codes.

• Communications of Mathematical Education
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• v.20 no.3 s.27
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• pp.483-502
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• 2006

In this research, we try to accomplish the main purpose of managing the special supplementary curriculum and set a model for its organization and management to the other schools by analyzing the result from the management of the special supplementary curriculum through mentoring lessons that are proposed in the 7th curriculum to provide the underachieved students with opportunities to study the subjects they couldn't understand during the regular curriculum.

• Journal of Korean Institute of Industrial Engineers
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• v.13 no.2
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• pp.105-115
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• 1987

Although there are many theoretical methods for the transformation of random variables. it is difficult to find probability density functions for the new random variables because of the complexity in mathematics. The author developed a simulation model solving the above difficulties using FBI (Fortran Based Interpreter) routines. The FBI is a kind of language Interpreter analyzing the arithmetic statement in character data forms. In this paper. the FBI routines will be explained and the structure and applications of simulation model will be also demonstrated. Polynomial curve fitting method is applied to define the probability density function which can not be defined by well-known pdf. This program can also be used for instructing mathematical statistics and identifying distribution of the simulated data.

• The Mathematical Education
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• v.49 no.2
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• pp.267-279
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• 2010

Mathematics is the subject which is distinctive in logical hierarchy, so the dificiency of prior learning or lack of understanding can result in learning disabilities of follow-up study. To minimize the learning disabilities, we should percieve student's problems and correct them through "Error Analysis" so that they can make up meaningful learning. Especially, in the case of division, its meaning is various, and the interpretation of the quotient and the remainder is the difference according to the caculation results, so students are likely to make errors often. Therefore, in this study, I presented the measures of how to instruct them under the circumstances in which division is applied by analyzing examples of incorrect answers.