• Journal of the Korean School Mathematics Society
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• v.21 no.1
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• pp.63-89
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• 2018

In this study, the researcher developed a course integrated mathematical problem posing activities in order to enhance pre-service mathematics teachers' ability to carry out problem posing activities in mathematics classroom, and examined the changes of pre-service mathematics teachers' perceptions about problem posing through the course. The problem posing course developed in this study consisted of three stages: education on the theories regarding problem posing; activities with problem posing; development and implementation of problem posing tasks. According to the results of the questionnaires, interviews, and class journals data analysis, the problem posing experiences provided in this study were very effective in improving pre-service mathematics teachers' understanding of the problem posing strategies and the benefit of problem posing activities to student learning. Particularly, the experience in various problem posing activities and the implementation experience of problem posing provided in the course played a key role in the improvement of pre-service mathematics teachers' understanding of problem posing and PCK.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1838-1845
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• 2011

This paper deals with coupled electromagnetic-thermal field analysis for thermal fluid analysis of oil immersed power transformer. Electric power losses are calculated from electromagnetic field analysis and are used as input source of thermal field analysis based on computational fluid dynamics(CFD). Particularly, In order to accurately predict the temperature rise in oil immersed power transformer, the thermal problem should be coupled with the electromagnetic problem. Moreover, to reduce analysis region, the heat transfer coefficient is applied to boundary surface of the power transformer model. The coupling method results are compared with the experimental values for verifying the validity of the analysis. The predicted temperature rises show good agreements with the experimental values.

• Journal of The Korean Association For Science Education
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• v.11 no.2
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• pp.67-77
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• 1991

In this paper, current research papers on Physics Problem Solving were analyzed according to the types of research purpose, method, subject and content of Physics, by using 3 Proceedings and 4 kinds of Journal, that is, the International Workshop(1983, Paris, France) and Conference (1983, Utrecht, The Netherlands) and Seminar(1987, Cornell University, U. S. A.) on Physics Education, and Journal of Research in Science Teaching (1984-1990) and Science Education (1986-1990). and Inter national Journal of Science Education(l987-1988) and Cognitive Science(1989-1990). There were 98 research papers on Problem Solving and among them 37 papers on Physics Problem Solving were selected for analyzing. The results of analysis are as follows; 1) The studies on Model of Novice Student were 22(59%), And those on Model of Desired Preformance, on Model of learning and on Model of Teaching were all much the same. 2) The theoretical studies were 10(27%), and the experimental ones 27(73%). Among the experimental studies, there were 16(59%) by using the written test, and 7(26%) by using the thinking aloud method. 3) The studies about university students as subjects were 20(54%). Probably, it seems the reason that most of researchers on Physics Problem Solving were professors of university or graduate students. 4) Among the various fields of Physics, the studies on Mechanics were 24(63%) and those on E1ectromagnetics 6(16%). or graduate students.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.3 s.258
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• pp.355-364
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• 2007

Multidisciplinary design optimization based on independent subspaces (MDOIS) is a simple and practical method that can be applied to the practical engineering MDO problems. However, the current version of MDOIS does not handle the common design variables. A new version of MDOIS is proposed and named as MDOIS/2006. It is a two-level MDO method while the original MDOIS is a single-level method. At first, system analysis is performed to solve the coupling in the analysis. If the termination criteria are not satisfied, each discipline solves its own design problem. Each discipline in the lower level solves the problem with common design variables while they are constrained by equality constraints. In the upper level, the common design variables of related disciplines are determined by using the optimum sensitivity of the objective function. To validate MDOIS/2006, mathematical problem and NASA test bed problem are solved. The results are compared with those from other MDO methods. Finally, MDOIS/2006 is applied to flow patterner design and shows that it can be successfully applied to the practical engineering MDO problem.

• Human Ecology Research
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• v.51 no.4
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• pp.371-382
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• 2013

The purpose of this study is to investigate children's emotional problems (attention problem, aggression, somatic symptom, social withdrawal, depression) and to examine the relationship between children's emotional problems with family characteristics (parent education, parent job, family income), life-styles (gaming times, TV times, sleep time). The sample was 2,140 collections of second grade children and their parents who participated in Korea Youth Panel Survey on 2011. We analyzed the data which were collected by means of questionnaires and the data were analyzed with t -test, ANOVA, Pearson correlation analysis, and regression analysis with SPSS ver. 19.0. The results were summarized as follows. The level of children's emotional problem was relatively low on average. There is a significant difference in the children's emotional problems according to family characteristics and life-styles. There was a relationship between children's emotional problems (attention problem, aggression, somatic symptom, social withdrawal, depression) and life-styles (gaming times, TV times). The significant factors influencing the children's emotional problems are connected with father's education, mother's job, family income, family characteristics, gaming time and TV time of life style. It is noted that parent education level was an important factor for children's attention problem and aggression. Amongst children's life-styles, gaming time and TV time are negative factors for social withdrawal and depression.

• Journal of Families and Better Life
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• v.29 no.4
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• pp.175-186
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• 2011

The purpose of this study was to explore the differences in interactive peer play according to the type of problem behavior. The subjects were 112(67 boys, 45 girls) S-year-old children at 25 daycare centers in Seoul, Gyeonggi, and Gyeongsang areas. Instruments included the Preschool Behavior Questionnaire(PBQ; Behar & Stringfield, 1974) and the Penn Interactive Peer Play Scale(PIPPS) in both the teacher version(Choi & Shin, 2008) and the parent version(Fantuzzo, Mendez, & Tighe, 1998). The data were analyzed with descriptive statistics, cluster analysis, t-test, and one-way ANOVA using the SPSS 18.0 software program. The results showed that the clusters of problem behaviors on the PBQ could be grouped into four categories; 'hostility-aggressiveness', 'hyperactivity- distractibility', 'anxiety-fear', and 'combined'. In addition, group differences among the problem behaviors were significantly found in 'play disruption' and 'play disconnection' but not in 'play interaction' of the PIPPS on teachers' and parents' ratings. Specifically, group differences were not found in the parental reports, while significant group differences were noted in the 'play disconnection on PIPPS component of the teachers' reports.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.827-833
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• 2011

Directional MAC protocols have drawn great attentions recently in super high speed wireless local/personal area networks due to their higher antenna gain, better spatial reuse, longer transmission range, and lower interference. Despite of these merits, directional MAC protocols suffer from deafness problem. The deafness problem occurs if a node does not answer an RTS frame addressed to it. To overcome this problem, directional MAC protocols have aimed at avoiding the deafness problem using multiple control frames or advance notice techniques or distinguishing deafness from collision. In this paper, we analyze the performance of these schemes in deafness environments with some scenarios. Through performance analysis, we compare the performance of these schemes through evaluating actual network throughput.

• The Mathematical Education
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• v.49 no.4
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• pp.523-540
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• 2010

The purpose of the study were to analyze MathThematics textbooks and Korean middle school mathematics and to investigate the difference among the textbooks in the view of mathematical communication. According to the results, the textbook developers made a variety of efforts to develope students' mathematical communication ability. Students were encouraged to communicate with others about their mathematical ideas or problem solving processes in words or writing by means of discussion, oral report, presentation, journal, etc. MathThematics textbooks provided student self-assessment opportunity to improve student performance in problem solving, reasoning, and communication. In communication assessment, students can assess their use of mathematical vocabulary, notation, and symbols, the use of graphs, tables, models, diagrams and equation to solve problem and their presentation skills. The assessment activities would make a positive impact on the development of students' mathematical communication ability. MathThematics textbooks provided a variety of problem situation including history, science, sports, culture, art, and real world as a topic for communication, however, the researcher found that some of Korean textbooks depends heavily on mathematical problem situations.

• Computers and Concrete
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• v.29 no.4
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• pp.247-253
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• 2022

In this study, the problem of discontinuous contact in two functionally graded (FG) layers resting on a rigid plane and loaded by two rigid blocks is solved by the finite element method (FEM). Separate analyzes are made for the cases where the top surfaces of the problem layers are metal, the bottom surfaces are ceramic and the top surfaces are ceramic and the bottom surfaces are metal. For the problem, it is accepted that all surfaces are frictionless. A two-dimensional FEM analysis of the problem is made by using a special macro added to the ANSYS package program The solution of this study, which has no analytical solution in the literature, is given with FEM. Analyzes are made by loading different Q and P loads on the blocks. The normal stress (σy) distributions at the interfaces of FG layers and between the substrate and the rigid plane interface are obtained. In addition, the starting and ending points of the separations between these surfaces are determined. The normal stresses (σx, σy) and shear stresses (τxy) at the point of separation are obtained along the depth. The results obtained are shown in graphics and tables. With this method, effective results are obtained in a very short time. In addition, analytically complex and long problems can be solved with this method.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.4
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• pp.198-204
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• 2009

It is one of important and interesting topics in mathematics education to study the process of the logical thinking and the intuitive thinking in mathematical problem-solving abilities from the viewpoint of mathematical thinking. The main purpose of the present paper is to investigate on this problem with reference to secondary talented students (students aged 16~17 years). In particular, we focus on the relationship between the preference of mathematical thinking and their problem-solving abilities for logical-type problems by applying logistic regression analysis.