• 대한수학교육학회지:수학교육학연구
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• 제11권1호
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• pp.157-177
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• 2001

Modern society's technological and economical changes require high-level education that involve critical thinking, problem solving, and communication with others. Thus, today's perspective of mathematics and mathematics learning recognizes a potential symbolic relationship between concrete and abstract mathematics. If the problems engage students' interests and aspiration, mathematical problems can serve as a source of their motivation. In addition, if the problems stimulate students'thinking, mathematical problems can also serve as a source of meaning and understanding. From these perspectives, the purpose of my study is to prove that mathematical modeling tasks can provide opportunities for students to attach meanings to mathematical calculations and procedures, and to manipulate symbols so that they may draw out the meanings out of the conclusion to which the symbolic manipulations lead. The review of related literature regarding mathematical modeling and model are performed as a theoretical study. I especially concentrated on the study results of Freudenthal, Fischbein, Lesh, Disessea, Blum, and Niss's model systems. We also investigate the emphasis of mathematising, the classified method of mathematical modeling, and the cognitive nature of mathematical model. And We investigate the purposes of model construction and the instructive meaning of mathematical modeling. In conclusion, we have presented the methods that promote students' effective model construction ability. First, the teaching and the learning begins with problems that reflect reality. Second, if students face problems that have too much or not enough information, they will construct useful models in the process of justifying important conjecture by attempting diverse models. Lastly, the teachers must understand the modeling cycle of the students and evaluate the effectiveness of the models that the students have constructed from their classroom observations, case study, and interaction between the learner and the teacher.

• 대한수학교육학회지:수학교육학연구
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• 제20권1호
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• pp.73-84
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• 2010

학교수학에서 다루는 수학적 모델링의 일반적인 특성은 하나의 실제적인 문제를 해결하기 위하여 수학적 모델을 도입하고 이를 풀어서 실제적인 문제에 답을 제시하는 일회적인 경우가 많다. 그러나 실제적인 문제는 일회적인 모델링으로는 해결되지 않거나 그 해가 충분히 정밀하지 못한 경우가 있다. 본 연구는 여러 가지 변인을 가진 실제적인 문제를 해결하기 위해 수학적 모델을 구성할 경우, 구성한 수학적 모델의 해의 의미성을 분석해 보고 필요하면 더욱 정교한 해를 구할 수 있는 모델로 나아가는 수학적 모델링의 정교화 과정 모형을 구안하였다. 또한 그것을 수학교실에서 활용할 수 있는 수학적 모델링의 예를 제시함으로써 학교수학에서 수학적 모델링의 정교화를 다룰 수 있게 하였다.

• 대한수학회보
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• 제48권3호
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• pp.555-574
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• 2011

It is well known that the mathematical models provide very important information for the research of human immunodeciency virus type. However, the infection rate of almost all mathematical models is linear. The linearity shows the simple interaction between the T-cells and the viral particles. In this paper, a differential equation model of HIV infection of $CD4^+$ T-cells with Crowley-Martin function response is studied. We prove that if the basic reproduction number $R_0$ < 1, the HIV infection is cleared from the T-cell population and the disease dies out; if $R_0$ > 1, the HIV infection persists in the host. We find that the chronic disease steady state is globally asymptotically stable if $R_0$ > 1. Numerical simulations are presented to illustrate the results.

• Design & Manufacturing
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• 제13권2호
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• pp.6-11
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• 2019

In this study, we constructed the mathematical model to evaluate the roundness for plastic injection mold parts with complicated 3D curvatures. Mathematically we started off from the equation of circle and successfully derived an analytical solution so as to minimize the area of the residuals. On the other hand, we employed the numerical method the similar optimization process for the comparison. To verify the mathematical models, we manufactured and used a ball valve type plastic parts to apply the derived model. The plastic parts was fabricated under the process conditions of 220-ton injection mold machine with a raw material of polyester. we experimentally measured (x, y) position using 3D contact automated system and applied two mathematical methods to evaluated the accuracy of the mathematical models. We found that the analytical solution gives better accuracy of 0.4036 compared to 0.4872 of the numerical solution. The numerical method however may give adaptiveness and versatility for optional simulations such as a fixed center.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.71-74
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• 2001

In general, the PSS/E program based on RMS mathematical models is used for analyzing the steady state and transient stability phenomena of full-scale large power system. Whereas, the EMTDC program unlike PSS/E, studies the specific reduced small-scale power systems as a basis of instantaneous value mathematical models and used to analyze the Electro-Magnetic transient characteristics. The PSS/E provides various control models such as exciter, governor and PSS models, But there are few control models in EMTDC. In this paper, we developed EMTDC models for governor which have been applied in KEPCO system. The EMTDC models are developed by examining PSS/E control block and using User Define Model in addition to default.lib provided by EMTDC. we verify the correctness of developed governor models with PSS/E and EMTDC simulation results using Governor Step(GSTEP) method.

• Computers and Concrete
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• 제8권6호
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• pp.647-675
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• 2011

Our ability to predict hydration behavior is becoming increasingly relevant to the concrete community as modelers begin to link material performance to the dynamics of material properties and chemistry. At early ages, the properties of concrete are changing rapidly due to chemical transformations that affect mechanical, thermal and transport responses of the composite. At later ages, the resulting, nano-, micro-, meso- and macroscopic structure generated by hydration will control the life-cycle performance of the material in the field. Ultimately, creep, shrinkage, chemical and physical durability, and all manner of mechanical response are linked to hydration. As a way to enable the modeling community to better understand hydration, a review of hydration models is presented offering insights into their mathematical origins and relationships one-to-the-other. The quest for a universal model begins in the 1920's and continues to the present, and is marked by a number of critical milestones. Unfortunately, the origins and physical interpretation of many of the most commonly used models have been lost in their overuse and the trail of citations that vaguely lead to the original manuscripts. To help restore some organization, models were sorted into four categories based primarily on their mathematical and theoretical basis: (1) mass continuity-based, (2) nucleation-based, (3) particle ensembles, and (4) complex multi-physical and simulation environments. This review provides a concise catalogue of models and in most cases enough detail to derive their mathematical form. Furthermore, classes of models are unified by linking them to their theoretical origins, thereby making their derivations and physical interpretations more transparent. Models are also used to fit experimental data so that their characteristics and ability to predict hydration calorimetry curves can be compared. A sort of evolutionary tree showing the progression of models is given along with some insights into the nature of future work yet needed to develop the next generation of cement hydration models.

• 한국CDE학회논문집
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• 제20권2호
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• pp.93-103
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• 2015

In this study, we organize and explain various ways to construct 3D models in the 2D plane using Geogebra, mathematical education software that enables us to visualize dynamically the interaction between algebra and geometry. In these ways, we construct three unit vectors for 3 dimensions at a point on the Cartesian coordinates, on the basis of which we can build up the 3D models by putting together basic mathematical objects like points, lines or planes. We can apply the ways of constructing the 3 dimensions on the Cartesian coordinates to modeling of various structures in the real world, and have chances to translate, rotate, zoom, and even animate the structures by means of slider, one of the very important functions in Geogebra features. This study suggests that the visualizing and dynamic features of Geogebra help for sure to make understood and maximize learning effectiveness on mechanical modeling or the 3D CAD.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제7권2호
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• pp.101-117
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• 2003

In this paper, we give examples of models we have created for use in university mathematics courses. We explain the concept of linear transformation, investigate the roles of each component of 2 ${\times}$ 2 and 3 ${\times}$ 3 transformation matrices, consider the relation between sound and trigonometry, visualize the Riemann sum, the volume of surfaces of revolution and the area of unit circle. This paper illustrates how one can use Mathematica to visualize abstract mathematical concepts, thus enabling students to understand mathematics problems effectively in class. Development of these kinds of teaching and learning models can stimulate the students' curiosity about mathematics and increase their interest.

• 산업공학
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• 제15권1호
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• pp.40-48
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• 2002

Recently, in the competitive environments, every company recognizes the importance of supply network planning models. However, there are so many problems in correctly applying mathematical model to the real world. Because mathematical modeling packages charge planning managers with understanding the models and responsibility for generating plans, fast and accurate model cannot be generated with ease. In this paper, we design the model management system that helps planning managers flexibly create and modify mathematical models and manage model versions. We implement the system with model base concept.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제1권1호
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• pp.13-22
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• 1997

Cognitive psychology has provided valuable theoretical perspectives on learning mathematics. Based on the metaphor of the mind as an information processing device, educators and psychologists have developed detailed models of competence in a variety of areas of mathematical skill and understanding. Unquestionably, these models are an asset in thinking about the curriculum we want our students to follow. But any psychological paradigm has aspects of learning and knowledge that it accounts for well, and others that it accounts for less well. For instance, the paradigm of cognitive science gives us valuable models of the knowledge we want our students to acquire; but in picturing the mind as a computational device it reduces us to conceiving of learning in individualist terms. It is less useful in helping us develop effective learning communities in our classrooms. In this paper I review some of the significant accomplishments of cognitive psychology for mathematics education, and some of the directions that situated cognition theorists are taking in trying to understand knowing and learning in terms that blend individual and social perspectives.