• 한국정밀공학회지
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• 제20권8호
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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.

• 한국학교수학회논문집
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• 제23권1호
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• pp.45-65
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• 2020

이 연구는 수학적 모델링이 반영된 중학생 이차함수 교수·학습 과정에서 발생하는 의사소통을 분석한 것이다. 의사소통의 심층 분석을 위해 Sfard(2008)의 담화 이론과 언어 분석 틀(장현석, 김명창, 이봉주, 2019)을 적용하였다. 이차함수 개념을 학습하고 3개월이 지난 학생을 대상으로, 이차함수 수학적 모델링 교수·학습이 2019년 6월 둘째 주에(1차시) 실시되었다. 그 결과는 다음과 같다. 첫째, 학생 간 이차함수 이외의 선행 지식의 차이로 인해 의사소통-인지적 갈등이 발생하였다. 둘째, 의사소통 과정에서 서로 다른 관점의 문제 해결을 통해 지식을 확장하였다. 이러한 결과는 학생이 이차함수 개념의 이해를 기반으로 의사소통 과정에서 문제점을 명료히 드러내고 학생 간 협동을 촉진할 수 있었던 것으로 해석 가능하다.

• 대한가정학회지
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• 제48권6호
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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.

• 한국수학교육학회지시리즈A:수학교육
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• 제61권1호
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• pp.127-156
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• 2022

본 연구는 한국교육종단연구2013의 초등학교 6학년부터 중학교 3학년까지의 학생 데이터들을 활용하여 수학 학업성취도의 종단적인 변화양상에 따른 학업적 자아개념 및 교사와 부모의 학업적 지원이 수학 학업성취도에 미치는 직·간접적인 영향력을 종단적으로 살펴보았다. 분석결과, 그룹별 학업적 자아개념은 수학 학업성취도에 긍정적인 영향력을 미치는 것으로 나타났으며, 교사와 부모의 학업적 지원은 학업적 자아개념을 매개로 하여 수학 학업성취도에 긍정적인 영향력을 미치는 것으로 나타났다. 또한, 학업적 자아개념과 수학 수직척도점수에 미치는 직·간접적인 영향력은 부모의 학업적 지원 보다 교사의 학업적 지원이 더 많은 영향력을 미치는 것으로 나타났다. 이러한 점에 따른 교육적인 함의점을 논의하였다.

• 대한기계학회논문집
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• 제19권7호
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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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• 제5권1호
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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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• 제55권6호
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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.

• 대한가정학회지
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• 제43권9호
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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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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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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).

• 전력전자학회논문지
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• 제17권1호
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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.