• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.115-125
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• 2003

To analyze the applications of all types of mechanical systems, general purpose analysis programs have been developed and commercialized. However, it is customary to develop and use customized programs even though they sometimes require more work than a general purpose program. A customized program is simplified to adapt to a particular application from the beginning, is designed for small computers, and developed with hardware-in-the-loop in mind so it can be applied effectively. By adding design knowledge and bundling know-how to an analysis program, analysis time can be reduced. And because an analysis has to work in conjunction with other analysis programs, a proprietary program that the user can easily modify can be useful. In this thesis, a multi-body dynamics analysis system is presented using one of the most useful programming techniques, object-oriented concept. The object-oriented concept defines a problem from the physical world as an abstract object, an abstract model. The object becomes encapsulated with the data and method. Simulation is performed using the object's interface. It is then possible for the user and the developer to modify and upgrade the program without having particular knowledge of the analysis program. The method presented in this thesis has the following advantages. Since the mechanical components of the multi-body system converts independent modeling into a class, the modification, exchange, distribution, and reuse of elements are increased. It becomes easier to employ a new analysis method and interface with other S/W and H/W systems. To employ a new analysis method, there is no need to modify elements of the main solver and the Library. In addition, information can be communicated to each object through messaging. It makes the modeling of new elements easier using inheritance. When developing a S/W for the computer simulation of physical system, it is reasonable to use object-oriented modeling. Also, for multi-body dynamics analysis, it is possible to develop a solver that is user-oriented.

• Journal of the Korean School Mathematics Society
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• v.23 no.1
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• pp.45-65
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• 2020

This research is an analysis of communication that occurs during the quadratic function teaching and learning process of middle school students, which reflects mathematical modeling. For an in-depth analysis of the communication, Sfard(2008)'s discourse theory and language analysis framework were applied. A quadratic function mathematical modeling teaching and learning were conducted for the week second (1 hour) in June 2019 for students who studied the concept of a quadratic function and who passed a specified period (3 months). The results are as follows. First, The commo-gnitive conflict occurred because of differences in prior knowledge other than quadratic function among students. Second, in the course of communication, knowledge was expanded through problem-solving from different perspectives. These results can be interpreted as allowing students to clearly reveal problems in the communication process based on their understanding of the concept of quadratic functions and to facilitate cooperation among students. of the concept of quadratic functions and to facilitate cooperation among students.

• Journal of the Korean Home Economics Association
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• v.48 no.6
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• pp.71-82
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• 2010

This study examined the effects of parent-, peer-, and teacher-attachment on development of career maturity via the mediating effects of self concept. There were 2844 elementary school students, ages 12 to 13 years old, who participated in the Korean Youth Panel Survey. All data were used for the analyses. Gender differences were found in most of the variables, including attachment, self concept, and career maturity. The Structural Equation Modeling technique applied to the data revealed that there were both concurrent and lagged effects of attachment and self concept on career maturity. It was found that self concept played a mediating role on career maturity.

• The Mathematical Education
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• v.61 no.1
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• pp.127-156
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• 2022

This study used the data of students from the 6th grade to the 3rd grade of middle schoolin the Korean Educational Longitudinal Study 2013 and classified them into subgroups with similar longitudinal changes in math academic achievement. In addition, the influence of longitudinal changes in the group's academic self-concept and teachers and parents academic support on the longitudinal changes in math academic achievement were analyzed, either directly or indirectly. As a result of the analysis, it was found that the academic self-concept of each group had a positive influence on the academic achievement in mathematics. In addition, the academic support of teachers and parents was found to have a positive influence on the academic achievement in mathematics through the mediating of the academic self-concept. In terms of direct and indirect influence on academic self-concept and math vertical scale scores, it was found that teachers' academic support had more influence than parents' academic support. The educational implications of these points were discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1604-1618
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• 1995

In the process of mechanical assembly design, assembly modeling systems have been used mainly for the design verification before manufacturing by enabling to check the interference and/ or the dynamic and kinematic performance. However, the conventional assembly modeling systems have a shortcoming that they can not be used in the initial design stage but can be used only after the design is fully completed. In other words conventional assembly modeling systems provide bottom-up modeling which means that the detailed modeling of components must precede the definition of relationships between them. To resolve this problem, an assembly modeling system is proposed to provide a top-down modeling environment in which components and assembly can be modeled simultaneously. To this end, an assembly data structure suitable for top-down assembly modeling has been established. Feature positioning Module(FPM) using geometric constraints has been also developed. The Sekective Solving Method proposed for FPM is based on the priority between the constraint equations and enables the designer's intent expressed by geometric constraints to be maintained throughout the whole modeling process. Finally, the feature based modeling technique using two-level features has been developed. Two-level features include an abstract model and a detailed model in a merged form in non-manifold data frame.

• Management Science and Financial Engineering
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• v.5 no.1
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• pp.27-49
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• 1999

WebME is an Web-based integrated modeling environment that implements a multi-facetted modeling approach to mathematical model representation and management. Key features of WebME include the following: (i) sharing of modeling knowledge on the Web, (ii) a user-friendly interface for creating, maintaining, and solving models, (iii) independent management of mathematical models from conceptual models, (iv) object-oriented conceptual blackboard concept, (v) multi-facetted mathematical modeling modeling, and (vi) declarative representation of mathematical knowledge. This paper presents details of design and implementation issues that were encountered in the development of WebME.

• Human Ecology Research
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• v.55 no.6
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• pp.625-635
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• 2017

This study examined the mediating effect of self-concept on the relationship of peer victimization and social anxiety in middle school students. Study participants consisted of 235 (122 boys and 113 girls) first to third graders from three middle schools located in Seoul and Gyung-gi province. The School Violence Experience Scale and the Self-Concept Scale were used to measure research variables in the Korean version of Social Anxiety Scale for adolescents. Descriptive statistics and Pearson's correlation coefficients were calculated to examine the general tendency of study variables. In addition, structural equation modeling(SEM) was used to examine the mediating model. The study results were as follows. First, the level of peer victimization of the middle school students decreased the self-concept level; in addition, the self-concept level had a significant negative effect on the social anxiety level. Second, the self-concept level fully mediated the peer victimization and social anxiety relationship. In conclusion, a higher peer victimization level resulted in a lower self-concept level, that produced a higher social anxiety level in middle school students. The results suggested that implementing effective interventions to prevent peer victimization and encouraging a positive self-concept in middle school students would make a significant contribution to reducing social anxiety.

• Journal of the Korean Home Economics Association
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• v.43 no.9 s.211
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• pp.109-127
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• 2005

The present study examined the relationships among maternal attachment, self-concept, peer relationship, and school adjustment. The subjects were 293 Korean-Chinese elementary school students living in Yanji and Shenyang, China. The Inventory of Parent and Peer Attachment (Armsden & Greenberg, 1987), Social Competence Inventory(Doh & Falbo, 1999), and Self-Perception Profile for Adolesents(Harter, 1988) were used to measure the subjects' maternal attachment, and peer relationship, school adjustment, and self-concept, respectively. When structural equation modeling was applied, the results supported not only the model that maternal attachment and self-concept exert an influence on peer relationship, but also the model that they exert an influence on school adjustment. The results of this study suggest that the secure maternal attachment of Korean-Chinese works as an important mechanism that explains their peer relationship and adjustment at elementary school.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.166.2-166.2
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• 2011

Incheon Bay of Korea is one of the most famous regions for high tidal range. Ministry of Land, Transport and Maritime Affairs(MLTM) has implemented preliminary investigation for tidal power energy development in this area since 2006. Through field observations, various kinds of marine data consisting of depth and geography, marine weather, tidal currents, wave, seawater characteristics, geology, marine ecosystem and marine environment were gathered. To use these data efficiently for the determining of feasibility of developing and appropriateness of project scale, spatial data management and application system is essential. Therefore, in this study, the concept, methodology and procedure of spatial data modeling are defined for tidal energy development. Spatial data modeling consists of essential model relating to tidal energy directly and optional model including environmental factors. Essential model is composed with fundamental elements like as depth, geography, and several numerical modeling results(tide, tidal current, wave).

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.67-76
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• 2012

This paper proposes the aggregated modeling and control of integated boost-flyback converter (IBFC) for understanding of dynamics characteristic and designing of relevant controller. The basic concept of the aggregated modeling is to substitute the boost or the flyback converter with an equivalent current source. Since each converter with equivalent current source corresponds to the basic boost and flyback converters, the overall mathematical process is significantly simplified for the modeling. Afterwards each result is combined to construct the complete model of the IBFC, and the relevant controller is designed through the achieved small-signal model. Simulation and experimental results show excellent agreement with the theoretical expectations.