• Bulletin of the Korean Mathematical Society
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• v.34 no.2
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• pp.199-204
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• 1997

To develope the theory of BCI-algebras, the idel theory plays an important role. The first author [4] introduced the notion of T-ideal in BCI-algebras. In this paper, we first construct a special set, called T-part, in a BCI-algebra X. We show that the T-part of X is a subalgebra of X. We give equivalent conditions that the T-part of X is an ideal. By using T-part, we provide an equivalent condition that every ideal is a T-ideal.

• Korean Journal of Mathematics
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• v.17 no.3
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• pp.331-340
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• 2009

We show the existence of nonconstant periodic solution for the nonlinear Hamiltonian systems with some nonlinearity. We approach the variational method. We use the critical point theory and the variational linking theory for strongly indefinite functional.

• Bulletin of the Korean Mathematical Society
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• v.52 no.4
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• pp.1149-1167
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• 2015

We get a theorem which shows the existence of at least four $2{\pi}$-periodic weak solutions for the bifurcation problem of the Hamiltonian system with the superquadratic nonlinearity. We obtain this result by using the variational method, the critical point theory induced from the limit relative category theory.

• The Mathematical Education
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• v.47 no.2
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• pp.155-168
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• 2008

The theory of representation, which has been an important topic of epistemology, has long history of study. But it has diverse meaning according to the fields of argument. In this paper the author set the meaning of mathematical representation as the interrelation of internal and external representations. With this concept, the following items were studied. 1. Survey on the concepts of mathematical representations. 2. Investigation of pedagogical significance of the mathematical representations, taking into account the characteristics of school mathematics. 3. Recommendation of principles for teaching representation to cope with the problems that are related with cause of disliking each domain of the secondary school mathematics. This study is expected to enable the development of teaching methods to help students strengthening their ability to comprehend mathematical sentences.

• The Mathematical Education
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• v.42 no.2
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• pp.229-245
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• 2003

In this paper, we present a review of research perspectives and investigations in collegiate mathematics education from the four decades of development in the journal published by Korea Society of Mathematical Education. Research of mathematics education at the tertiary level, which had been a minor area in mathematics education, has made a significant development in the last decade in Europe md U.S.A. In this context, international journals for research in mathematics education were selected to comparatively examine and identify research trends and tasks in collegiate mathematics education. Based on the analysis of domestic at international journals, we present recommendations for further the development of Korean collegiate mathematics education research. First it is necessary to diversify the topics of educational research. Korean research of mathematics education at the tertiary level has been limited to the issues of curriculum developments, teacher education and computer technology. It is necessary to pursue more various topics such as conceptual development mathematical attitude and belief gender, socio-cultural aspect of teaching and teaming mathematics. Second, it is necessary to apply research methods for systematic investigations. It is important to note that international research of mathematics education introduces variety of research methods such as observation, interview, and survey in order to develop grounded theory of mathematics education. We end with pedagogical implications of the analyses presented and general conclusions concerning the perspectives for the future in collegiate mathematics education.

• Communications of Mathematical Education
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• v.35 no.4
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• pp.413-423
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• 2021

This study investigated the empty set which is one of the mathematical objects. We inquired some misconceptions about empty set and the background of imposing empty set. Also we studied historical background of the introduction of empty set and the axiomatic system of Set theory. We investigated the nature of mathematical object through studying empty set, pure conceptual entity. In this study we study about the existence of empty set by investigating Alian Badiou's ontology known as based on the axiomatic set theory. we attempted to explain the relation between simultaneous equations and sets. Thus we pondered the meaning of the existence of empty set. Finally we commented about the thoughts of sets from a different standpoint and presented the meaning of axiomatic and philosophical aspect of mathematics.

• Communications of Mathematical Education
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• v.31 no.3
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• pp.279-290
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• 2017

This study proposes a self learning material for understanding the key contents of Galois theory. This material is for teachers who have learned algebraic structures like group, field, and vector space which are related with Galois theory but do not clearly understand how algebraic structures are related with the solvability of polynomials and school mathematics. This material is likely to help them to overcome such difficulties. Even though proposed material is used mainly for self learning, the teachers may be helped once or twice by some professionals. In this article, two expressions 'solvability of polynomial' and 'solvability of equation' have the same meaning and 'teacher' means in-service mathematics teacher.

• The Mathematical Education
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• v.57 no.3
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• pp.231-246
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• 2018

In this paper, we applied Sfard's reification theory to analyze the secondary students' level of conceptualization with regard to the formula of quadratic equation. Through the generation and development of mathematical concepts from a historical perspective, Sfard classified the formulation process into three stages of interiorization, condensation, and reification, and proposed levels of formulation. Based on this theory, we constructed a test tool reflecting the reversibility of the nature of manipulation of Piaget's theory as a criterion of content judgement in order to grasp students' conceptualization level of the formula of quadratic equation. By applying this tool, we analyzed the conceptualization level of the formula of quadratic equation of the $9^{th}$ and $10^{th}$ graders. The main results are as follows. First, approximately 45% of $9^{th}$ graders can not memorize the formula of quadratic equation, or even if they memorize, they do not have the ability of accurate calculation to apply for it. Second, high school curriculum requires for students to use the formula of the quadratic equation, but about 60% of $10^{th}$ graders have not reached at the level of reification that they can use the formula of quadratic equation. Third, as a result of imaginarily correcting the error of the previous concept, there was a change in the levels of $9^{th}$ graders, and there was no change in $10^{th}$ graders.

• Research in Mathematical Education
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• v.20 no.1
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• pp.1-9
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• 2016

An accurate evaluation of educational process is a promise for the progress of education, because evaluation provides a meticulous idea of what has actually been achieved as a result of education. However, for all its significance in the educational fields, there are not many discussions about evaluation in South Korea. We believe that in order to overcome this discrepancy, diverse evaluation theories along with a discussion about the merits or demerits or each theory should be introduced in South Korea. We propose that Eisner's educational evaluation model may suggest alternative ways of perceiving evaluation. Eisner's educational evaluation model, named educational connoisseurship and criticism, emerged as an approach to educational evaluation from the methods used in art and literary criticism.

• The Mathematical Education
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• v.50 no.2
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• pp.135-148
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• 2011

We can say that the history of mathematics is the history on the development of the number system. The number starts from Natural number and is constructed to Integer number and Rational number. The Rational number is not the complete number analytically so that Real number is completed by the idea of the nested interval method. Real number is completed analytically, however, is not by algebra, so the algebraically completed type of the rational number, through the way that similar to the process of completing real number, is Complex number. The purpose of this study is to show the most appropriate way for the development of the human being thinking about the teaching and leaning of Complex number. To do this, We have to consider the proof of the existence of Complex number, the background of the introduction of Complex number and the background knowledge that the teachers to teach Complex number should have. Also, this study analyzes the knowledge to be taught of Complex number based on the anthropological theory of didactics and finally presents the teaching method of Complex number based on this theory.