• Structural Engineering and Mechanics
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• v.54 no.1
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• pp.69-85
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• 2015

In this paper, a receding contact problem for an elastic layer resting on two quarter planes is considered. The layer is pressed by a stamp and distributed loads. It is assumed that the contact surfaces are frictionless and only compressive traction can be transmitted through the contact surfaces. In addition the effect of body forces are neglected. Firstly, the problem is solved analytically based on theory of elasticity. In this solution, the problem is reduced into a system of singular integral equations in which contact areas and contact stresses are unknowns using boundary conditions and integral transform techniques. This system is solved numerically using Gauss-Jacobi integral formulation. Secondly, two dimensional finite element analysis of the problem is carried out using ANSYS. The dimensionless quantities for the contact areas and the contact pressures are calculated under various distributed load conditions using both solutions. It is concluded that the position and the magnitude of the distributed load have an important role on the contact area and contact pressure distribution between layer and quarter plane contact surface. The analytic results are verified by comparison with finite element results.

• Korean Journal of Human Ecology
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• v.22 no.3
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• pp.391-404
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• 2013

This study examined the moderating role of teacher-child relationship on the relation between children's problem behavior and peer victimization. Participants were 198 children(97 boys, 101 girls; recruited from classes with 5-6 year olds) and their kindergarten teachers. The teachers completed the rating scales to measure the children's peer victimization, problem behavior and teacher-child relationship. The collected data were analyzed using descriptive statistics, t-tests, correlations, and hierarchical multiple regressions. Boys and girls were analyzed separately. Results showed that children's problem behavior had positive relation to their peer victimization. Teacher-child relationship significantly related to children's peer victimization. Hierarchical regression analysis indicated that the interaction of boys' withdrawal behavior and teacher-child closeness predicted boy's peer victimization. Boys' withdrawal behavior, whose teachers demonstrated the lowest level of teacher-child closeness, associated significantly with their peer victimization. Boys' withdrawal and aggressive behavior had significant relation to their peer victimization, especially for the highest level of teacher-child conflictual relationship. Findings suggested the importance of teacher-child relationship in the context of intervention planning for peer victimization.

• Journal of Korean Society of Rural Planning
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• v.5 no.2 s.10
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• pp.14-23
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• 1999

This studys concerns with a critical issues of urban and rural integration for rurban development. Todays, many of urban-rural integrated cities are confronted with the negative effects of administrative boundary integration. The first problem is induced from the developmental gaps and different residential demands between the core-city and peripheral-county. The second problem is social-economic and administrative unification costs neglected. The third problem is the environmental pollutions and degradations in peripheral-county by rapid urbanization. The forth problem is the inequality of the public services and regional investments in the urban-rural Integrated cities. The fifth problem is the administrative relation and financial distribution between core-city and residual province when the urban-rural integrated core-city becomes large urban city. The results of the questionnaire analysis as follows. The first point, the preference of administrative boundary integration is different in intra-areas of urban-rural integrated county by it's location. The second point, the diversity of preference of residents depends on theirs job, age, resdential period, education and income level. So, administrative boundary integration must consider the many important factors which affect the socio-economic situations between the core-city and peripheral-county. In conclusion, residents' preference for the admistrative boundary integration depends on their situation without rational approach for macro regional development. In this contexts, comprehensive approach for the urban-rural administrative boundary integration is needed in consistent with rapid change of local government's functions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.412-418
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• 2007

An inverse optimal problem for homing guidance with angular constraint is addressed. The gains of BPN(Biased PN) are investigated by duality analysis related to the weighting matrices of the performance index in the LQ control problem. Moreover, the criteria for the existence of optimal gains are derived from the generalized Riccati equation. Based on the conditions we achieve the gain set of BPN to be optimal solution to the LQ problem with terminal constraints. To validate and demonstrate the proposed approach 3-DOF simulations are carried out.

• School Mathematics
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• v.12 no.3
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• pp.259-271
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• 2010

This study involves investigating problem posing practices for mathematically gifted first year middle school students in Korea. The overall purpose of this study is twofold: to examine the students' preferences on problem posing resources on the division algorithm and to analyze the approaches of the students' posing problems related to specific solution methods. To this end, the patterns of the problems are classified into 6 types such as 'routine' and 'nonroutine' problems associated with 3 levels of the original version of problems. Based on the analysis on the problems, we provide some implications about the nature of mathematically gifted students' problem posing practices in gifted education.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.397-414
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• 2005

In the existing literature, most of the purchasing models were developed only for retailers problem ignoring the constraint of storage capacity of retailers shop/showroom. In this paper, we have developed a deterministic model of wholesaler-retailers' problem of single product. The storage capacity of wholesaler's warehouse/showroom and retailers' showroom/shop are assumed to be finite. The items are transported from wholesaler's warehouse to retailers' Own Warehouse (OW) in a lot. The customer's demand is assumed to be displayed inventory level dependent. Demands are met from OW and that spaces of OW will immediately be filled by shifting the same amount from the Rented Warehouse (RW) till the RW is empty. The time duration between selling from OW and filling up its space by new ones from RW is negligible. According to relative size of the retailers' existing (own) warehouse capacity and the demand factors, different scenarios are identified. Our objectives are to optimize the cost functions of wholesaler and two retailers separately. To solve this problem, a real coded Genetic Algorithm (GA) with roulette wheel selection/reproduction, whole arithmetic crossover and non-uniform mutation is developed. Finally a numerical example is presented to illustrate the results for different scenarios. To compare the results of GA, Generalised Reduced Gradient Method has been used for the problem. Also, a sensitivity analysis has been performed to study the variations of the optimal average cost with respect to the different parameters.

• The Mathematical Education
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• v.57 no.3
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• pp.271-287
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• 2018

This is a case study that defined collaborative utterances and analyzed how they appear in the problem-solving process when 5th-grade students solved problems in groups. As a result, collaborative utterances consist of an interchange type and a deliver type and the interchange type is comprised of two process: the verification process and the modification process. Also, in groups where interchange type collaborative utterances were generated actively and students could reach an agreement easily, students applied the teacher's help to their problem-solving process right after it was provided and could solve problems even though they had some mathematics errors. In interchange-type collaborative utterances, each student's participation varies with their individual achievement. In deliver-type collaborative utterances, students who solved problems by themselves participated dominantly. The conclusions of this paper are as follows. First, interchange-type collaborative utterances fostered students' active participation and accelerated students' arguments. Second, interchange-type collaborative utterances positively influenced the problem-solving process and it is necessary to provide problems that consider students' achievement in each group. Third, groups should be comprised of students whose individual achievements are similar because students' participation in collaborative utterances varies with their achievement.

• Journal of Gifted/Talented Education
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• v.12 no.4
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• pp.120-130
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• 2002

We have analyzed students' reports on a problem for 'adhesive tape' and 'fractal diffraction' among ten assigned problems in the first Korean youth physics tournament (KYPT). There were three high school team' s reports and one middle school team' s report on this problem. However, many students failed to solve the 'fractal diffraction' problem correctly due to having no idea of fractal. This problem was found to be most difficult one for the participated students among ten assigned problems given in the first KYPT.

• Journal of Korean society of Dental Hygiene
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• v.14 no.4
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• pp.555-561
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• 2014

Objectives : The aim of this study was to investigate the factors related to stress perception. Methods : A self-reported questionnaire was filled out by 109 people living in Gimpo city from January 16 to April 15, 2013. The data were analyzed using SPSS window ver. 19.0(IBM CO., Armonk, NY, USA) for t-test, one-way ANOVA, and multiple linear regression analysis. Results : Men and group of 59 years old tended to have higher stress perception than women and those who over 60 years old, but the results were not statistically significant. Stress perception was higher among the group with systemic dryness and oral dryness(each${\geq}1$) and the group reporting high difficulty in daily living due to oral problem(${\geq}2$)(p<0.05). Especially, the factor that was most correlated to stress perception was systemic dryness(${\beta}$=0.347) followed by problem of daily living for oral problem(${\beta}$=0.278, p<0.01). Conclusions : Systemic dryness and oral problem can increase the level of stress perception, mouth dryness and oral problems are a part of stress responses. Therefore, the regular health checkup must be done and early treatment to reduce stress perception as well as negative aspects caused by stress. It will contribute to the enhancement of public health and life of quality.

• Journal of the Korean Home Economics Association
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• v.50 no.1
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• pp.103-119
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• 2012

The purpose of this study was to explore the mediating effects of preschooler's effortful control on the relationship between maternal emotional availability and preschooler's social skills and problem behaviors. One hundred-thirty six 5-year-old preschoolers and their mothers participated in this study. Instruments for this study were the Emotional Availability Scale for maternal emotional availability, the Delay task, and the Child Behavior Questionnaire for preschooler's effortful control, and the Social Skill Rating Scale, K-CBCL 1.5-5 and K-TRF for preschooler's social skills and problem behaviors. The resulting data were analyzed using descriptive statistics, partial correlation, and structural equation modeling analysis. As predicted, the preschooler's effortful control mediated the effects of maternal emotional availability on preschooler's social skills and problem behaviors. In conclusion, the preschooler's effortful control mediates the effects of emotion related socialization behavior on the preschooler's socio-emotional adjustment.