• Proceedings of the Korea Society of Mathematical Education Conference
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• 2010.04a
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• pp.225-225
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• 2010

몇 가지 교구를 사용하여 여러 대상의 무게중심을 찾아보고 수학적으로 정리한다. (1) 피노키오의 늘어나는 코 실험: 막대를 가장 길게 쌓는 방법 (2) 점 무게중심 실험: 일렬로 매단 추들의 무게중심, 삼각형, 사각형의 꼭짓점에 매단 추들에 대한 무게중심 (3) 선 무게중심 실험 : 삼각형, 사각형의 변에 대한 무게중심 (4) 면무게중심 실험 : 삼각형, 사각형, 오각형의 면의 무게중심

• Journal of Science Education
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• v.34 no.1
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• pp.175-184
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• 2010

We agree with Hanna and Jahnke's assertion on the use of arguments from physics in mathematical proofs and analyze their educational example of the use of arguments from physics in the proof of the center of gravity of a triangle. Moreover, we suggest practical models for the center of gravity of a triangle for the demonstration in a classroom. Comparing with the traditional mathematical arguments, the role of concepts and models from physics in arguments from physics will be clearly pointed out. Also, the necessity for arguments from physics in the classroom will be discussed in this paper.

• Journal of the Korean School Mathematics Society
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• v.9 no.1
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• pp.93-104
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• 2006

The centroid of triangle is physical property but almost mathematics teachers do not teach centroid by the help of experiments an so they have misconception on principle of centroid. In this paper we investigate whether teachers have made an experiment on centroid of triangle, and we check up on the level of understanding on centroid for mathematics teachers. We introduce the method of teaching centroid and study the process of generalization about centroid of triangle for gifted students.

• Communications of Mathematical Education
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• v.13 no.1
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• pp.305-316
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• 2002

벡터는 수학 문제해결을 위한 중요한 도구로써, 벡터를 이용한 문제해결 과정에서 학생들은 수학적 탐구 활동에 관련된 풍부한 경험을 가질 수 있다. 본 연구에서는 벡터를 이용하여 삼각형의 무게중심에 관한 정리를 증명하기 위한 수학적 탐구 능력이나 아이디어를 학생들이 준비할 수 있도록 정리 증명과 관련된 몇몇 문제들을 체계화하여 제시하였다. 이 문제들을 해결하는 과정에 관련된 탐구 능력을 추출하였으며, 체계화된 문제에 바탕을 둔 무게중심에 관한 정리 증명을 제시하였고, 증명 과정과 관련된 수학적 탐구 능력을 제시하였다.

• Communications of Mathematical Education
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• v.19 no.3 s.23
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• pp.471-484
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• 2005

무게중심에 관련된 연구는 수학과 물리, 수학과 공학 분야에서 폭넓은 활용을 가지는 간학문적 접근의 한 예이며, 실생활에서의 경험을 수학적 개념 및 방법에 관련시킬 수 있는 흥미로운 영역이라 할 수 있다. 본 연구에서는 문헌연구를 통해 균일한 다각형판의 무게중심 개념을 소개하고, 삼각형판과 볼록사각형판의 무게중심의 위치 및 성질을 조사하고, 이를 확장하여 볼록n각형판에서 무게중심의 위치를 탐구하였다.

• Journal of Educational Research in Mathematics
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• v.26 no.3
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• pp.421-442
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• 2016

This study analyzed characteristics which emerged while 38 secondary school teachers observed a video clip about a centroid of triangles instruction. The aim of this study based on the analysis was to deduce implications in terms of the various means which would enhance teachers' knowledge in teaching mathematics and assist in designing mathematics education programs for teachers and professional development initiatives. To achieve this goal, this research firstly reviewed previous studies relevant to the 'Knowledge Quartet' as a framework of analyzing teachers' knowledge in mathematics instructions. Secondly, this study probed the observation results from the teachers in the light of the KQ. Therefore, some issues in the teacher education program for teaching mathematics were thirdly identified in the categories of 'Foundation', 'Transformation', 'Connection', and 'Contingency' based on the analysis. This research inspires the elaboration of what features have with regard to effective teachers' knowledge in teaching mathematics through the analyzing process and additionally the elucidation of essential matters related to mathematics education on the basis of the analyzed results.

• Communications of Mathematical Education
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• v.25 no.4
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• pp.681-691
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• 2011

Mathematics curriculum according to 2009 Revised National Curriculum suggests that school mathematics must cultivate interest and curiosity about mathematics in addition to creative thinking ability of students, and ability and attitude of observing and analyzing many things happening around. Centroid of a triangle in 2007 Revised National Curriculum is defined as 'an intersection point of three median lines of a triangle' and it has been instructed focusing on proof study that uses characteristic of parallel lines and similarity of a triangle. This could not teach by focusing on the centroid itself and there is a problem of planting a miss concept to students. And therefore this writing suggests centroid must be taught according to its essence that centroid is 'a dot that forms equilibrium', and a justification method about this could be different.

• Communications of Mathematical Education
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• v.23 no.4
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• pp.1059-1078
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• 2009

In this paper we study metric equalities related with distance between excenter and other points of triangle. Especially we find metric equalities between excenter and incenter, circumcenter, center of mass, orthocenter, vertex, prove these formulas, and transform these formulas into new formula containing another elements of triangle. We in detail describe proof process of these equalities, indicate references of some formulas that don't exist within secondary school curriculum.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1174-1182
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• 1999

Recently the shape information of the visual object in the scene is more important, as the completion of the MPEG-4 standard and the progress of the MPEG-7 standard. This paper represents the study of effective coding method of vertices that are used in the polygonal approximation to represent the feature of visual object. In the proposed method, we make the centers of gravity of triangles that are made using the vertices of polygonal approximation and encode them sequentially We can get a coding gain because the centers of the gravity of triangles have narrower dynamic ranges.

• School Mathematics
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• v.7 no.4
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• pp.391-402
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• 2005

The purpose of this study is to resolve misunderstanding for centroid of a triangle and to clarify several logical problems in finding the centroid of a Polygon. The conclusions are the followings. For a triangle, the misunderstanding that the centroid of a figure is the intersection of two lines that divide the area of the figure into two equal part is more easily accepted caused by the misinterpretation of a median. Concerning the equilibrium of a triangle, the median of it has the meaning that it makes the torques of both regions it divides to be equal, not the areas. The errors in students' strategies aiming for finding the centroid of a polygon fundamentally lie in the lack of their understanding of the mathematical investigation of physical phenomena. To investigate physical phenomena mathematically, we should abstract some mathematical principals from the phenomena which can provide the appropriate explanations for then. This abstraction is crucial because the development of mathematical theories for physical phenomena begins with those principals. However, the students weren't conscious of this process. Generally, we use the law of lever, the reciprocal proportionality of mass and distance, to explain the equilibrium of an object. But some self-evident principles in symmetry may also be logically sufficient to fix the centroid of a polygon. One of the studies by Archimedes, the famous ancient Greek mathematician, gives a solution to this rather awkward situation. He had developed the general theory of a centroid from a few axioms which concerns symmetry. But it should be noticed that these axioms are achieved from the abstraction of physical phenomena as well.