• The Korean Journal of Rheology
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• v.9 no.2
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• pp.60-65
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• 1997

PFP성형기술은 사출성형시 수지를 금형내에 환전히 채운후 저압의 공기를 이용하여 기포를 발생시켜 수지의 체적수축분을 기포의 성장에 의해 보상해주는 기술이다. 이방법은 일반 사출성형에서 많이 발생하는 싱크마크나 휨과 같은 변형문제를 해결하여 줄수 있으며 높은 압력을 필요로하지 않는다는 잇점을 가지고 있으나 이러한 최신공정에 대한 체계적인 연구는 미흡한 실정이다. 최근에 제시된 PFP성형공정의 모델링은 기포의 성장이 수지의 체 적수축에 의한 것이라는 가정을 근거로 기포핵이 생성된 이후의 기포성장을 모사하였으며 모델링에 해석결과는 몇가지 가정에도 불구하고 실험결과를 잘 설명하였다. 본 연구에서는 모델링이 가지는 문제점을 분석하고 기포성장의 메카니즘을 보다 체계적으로 이해하기 위하 여 실험적인 방법을 적용하였다. 많은 인자들을 효과적으로 고려하기 위하여 실험계획법을 적용하였으며 이를통하여 기포핵의 생성과 기포의 성장에 공기압 등이 매우 중요한 역할을 한다는 사실을 확인하였다. 이러한 결과는 모델링과 함께 PFP공정에 대한 체계적인 이해 뿐만 아니라 금형설계 및 성형조건의 설정등의 실제적인 문제해결에도 도움이 될것으로 기 대된다.

• Computational Structural Engineering
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• v.3 no.3
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• pp.125-131
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• 1990

A finite element technique for the time dependent large structural problems is presented. It is based on the error estimation for the bases of solution spaces. An a-posteriori energy norm of residual error serves as the error indicator. Mode shapes which are calculated by scaling the Ritz vectors are applied to discretize the continuous spatial domain. Finally, the performance of the proposed methods is demonstrated by solving simple examples.

• Journal of the Korean Geographical Society
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• v.39 no.3
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• pp.444-456
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• 2004

Recently spatial modeling that combined GIS and Cellular Automata(CA) which are based on dynamic process modeling has been discussed and investigated. However, CA-based spatial modeling in previous research only provides the general modeling framework and environment, but lacks of providing simulation or transition rules for modeling. This study aims to propose a methodology for extracting spatial relation rules using GIS and Knowledge Discovery in Database(KDD) methods. This new methodology has great potentials to improve CA-based spatial modeling and is expected to be applied into several examples including urban growth simulation modeling.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.634-636
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• 2010

소비자의 행동이론은 경영학의 주된 관심사이다. 소비자의 소비 행동패턴 이론은 소비자의 합리적 소비에 근거한 선호도로써, 선택의 문제를 주요한 연구대상으로 삼고 있다. 하지만 본 모델링은 소비자의 선택을 선호의 문제로 취급하는 기호에 의존하기 보다는, 상권의 측정가능한 크기에 의존하는 수동적 의미의 소비패턴을 산정하게 된다. 단순한 몇 가지 가정을 기반으로 하여 상권이 미치는 영향력을 상권의 거리와 상권의 크기로만 한정할 경우, 최적 경로에 따른 합리적인 소비함수 모델링을 만들 수있다. 상권의 거리 및 상권의 크기로 상권의 범위를 제한 할 경우, 물리학 분야인 전기자기학 중에서 쿨롱의 법칙으로부터 유도된 전기장의 개념을 도입하여 상권의 의미를 재해석할 수 있다. 향후 본 모델링에 대한 소비자 행동패턴의 실질적인 검증 및 추가 도입변수 및 에러항을 도입한 일반적인 모델링으로 발전시킬 수 있고, 그 또한 추가 연구주제가 될 수 있다.

• Education of Primary School Mathematics
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• v.21 no.3
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• pp.351-374
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• 2018

The purpose of this study is to support the understandings of teachers about the instructional strategies of collaborative problem solving and mathematical modeling as presented in the 2015 revised mathematics curriculum. For this, tasks of the Cubes unit from six grader's and lesson plans were developed. The specific problem solving processes of students and the practices of teachers which appeared in the classes were analyzed. In the course of solving a series of problems, students have formed a mathematical model of their own, modifying and complementing models in the process of sharing solutions. In particular, it was more effective when teachers explicitly taught students how to share and discuss problem-solving. Based on these results this study is expected to suggest implications on how to foster students' problem solving ability as mathematical subject competency in elementary classrooms.

• Journal of The Korean Association For Science Education
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• v.34 no.5
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• pp.479-490
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• 2014

The purpose of this study is to develop an argument-based modeling strategy, utilizing writing and argumentation for communication in science education. We need to support students and teachers who have difficulty in modeling in science education, this strategy focuses on development of four kinds of factors as follows: First, awareness of problems, recognizing in association with problems by observing several problematic situations. Second is science concept structuralization suggesting enough science concepts by organization for scientific explanation. The third is claim-evidence appropriateness that suggests appropriate representation as evidence for assertions. Last, the use of various representations and multimodal representations that converts and integrates these representations in evidence suggestion. For the development of these four factors, this study organized three stages. 'Recognition process' for understanding of multimodal representations, and 'Interpretation process' for understanding of activity according to multimodal representations, 'Application process' for understanding of modeling through argumentation. This application process has been done with eight stages of 'Asking questions or problems - Planning experiment - Investigation through observation on experiment - Analyzing and interpreting data - Constructing pre-model - Presenting model - Expressing model using multimodal representations - Evaluating model - Revising model'. After this application process, students could have opportunity to form scientific knowledge by making their own model as scientific explanation system for the phenomenon of the natural world they observed during a series of courses of modeling.

• Education of Primary School Mathematics
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• v.26 no.3
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• pp.141-162
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• 2023

Recently, in school mathematics, classes using mathematical modeling are attracting attention to improve students' mathematical problem-solving skills. However, existing preceding studies have been conducted mainly on elementary, middle, and high school or in-service teachers, so it may be limited to apply the contents and results of the research as it is to pre-service teachers, who are future professors. Therefore, this study examined the school days' experiences of mathematical modeling for pre-service elementary school teachers. In addition, in order to provide a positive experience for mathematical modeling, mathematical modeling problem creation activities were conducted through group activities, and the results and their perceptions were examined. As a result of the study, elementary school preservice teachers had very little experience with mathematical modeling activities during their elementary, middle, and high school days. It was found that there is a deficiency in creating an appropriate mathematical modeling problem suitable for the level of elementary school students. In addition, it was found that they had a positive perception of mathematical modeling after participating in the study. Based on these results, implications for the training process for preservice teachers were suggested.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.1
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• pp.93-117
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• 2019

Considering precedent studies in which research subjects are mainly confined to secondary school students or higher grade students of elementary schools, we can notice that there has been implicit agreement that instruction of mathematical modeling is quite difficult to lower grade students of elementary schools. Compared to this tendency, this study aims to examine the possibility of instruction of mathematical modeling for all of school ages, and more specifically, the applicability of mathematical modeling tasks to lower graders. To do this, we developed a mathematical modeling task proper to cognitive characteristics of lower graders and applied this task to the second graders. Based on the research results by lesson observation and the teacher's reflection, some didactical suggestions were induced for teaching the lower grade elementary school students mathematical modeling.

• Communications of Mathematical Education
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• v.37 no.2
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• pp.257-276
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• 2023

Mathematical modeling can be described as a series of processes in which real-world problem situations are understood, interpreted using mathematical methods, and solved based on mathematical models. The effectiveness of mathematics instruction using mathematical modeling has been demonstrated through prior research. This study aims to explore insights for mathematical modeling instruction by analyzing the metacognitive characteristics shown in the mathematical modeling cycle, according to the mathematical thinking styles of elementary math gifted students. To achieve this, a mathematical thinking style assessment was conducted with 39 elementary math gifted students from University-affiliated Science Gifted Education Center, and based on the assessment results, they were classified into visual, analytical, and mixed groups. The metacognition manifested during the process of mathematical modeling for each group was analyzed. The analysis results revealed that metacognitive elements varied depending on the phases of modeling cycle and their mathematical thinking styles. Based on these findings, didactical implications for mathematical modeling instruction were derived.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.2
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• pp.138-149
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• 2000

Various modeling techniques for ultrasonic wave propagation and scattering problems in finite solid media are presented. Elastodynamic boundary value problems in inhomogeneous multi-layered plate-like structures are set up for modal analysis of guided wave propagation and numerically solved to obtain dispersion curves which show propagation characteristics of guided waves. As a powerful modeling tool to overcome such numerical difficulties in wave scattering problems as the geometrical complexity and mode conversion, the Boundary Element Method(BEM) is introduced and is combined with the normal mode expansion technique to develop the hybrid BEM, an efficient technique for modeling multi mode conversion of guided wave scattering problems. Time dependent wave forms are obtained through the inverse Fourier transformation of the numerical solutions in the frequency domain. 3D BEM program development is underway to model more practical ultrasonic wave signals. Some encouraging numerical results have recently been obtained in comparison with the analytical solutions for wave propagation in a bar subjected to time harmonic longitudinal excitation. It is expected that the presented modeling techniques for elastic wave propagation and scattering can be applied to establish quantitative nondestructive evaluation techniques in various ways.