• Honam Mathematical Journal
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• v.31 no.1
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• pp.87-95
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• 2009

In this paper, we introduce the concepts of IVF ${\alpha}$-irresolute mappings and IVF ${\alpha}$-irresolute open mappings and investigate some characterizations for them on the interval-valued fuzzy topological spaces.

• Honam Mathematical Journal
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• v.30 no.3
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• pp.557-566
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• 2008

In this paper, we introduce the concept of IVF weakly continuity and investigate some characterizations for IVF weakly continuous mappings on the interval-valued fuzzy topological spaces. We introduce and study the concepts of almost IVF compactness and nearly IVF compactness.

• Communications of the Korean Mathematical Society
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• v.16 no.4
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• pp.659-666
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• 2001

The aim of this paper is to derive the analytical so-lution of the queue: H$_{r}$/M/c/k/N for machine interference with balking and reneging, and FIFO (first in, first out) service disci-pline.e.

• Communications of the Korean Mathematical Society
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• v.18 no.4
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• pp.643-652
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• 2003

In this paper we introduce the concepts of the Mc-Shane-Stieltjes integral and the Denjoy-McShane-Stieltjes integral for Banach-valued functions and give a characterization of the Mc-Shane-Stieltjes integrability and investigate some properties of the Denjoy-McShane-Stieltjes integral.

• Communications of the Korean Mathematical Society
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• v.23 no.1
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• pp.125-131
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• 2008

We introduce and study the concepts of strong generalized neighborhood systems, SGNS and sg-open sets. We also introduce and investigate the concept of (${\psi},\;{\psi}^'$)-continuity and sg-continuity on SGNS's.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.2
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• pp.351-357
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• 2011

In this paper, we introduce certain concepts which we will provide us with a perspective and insight into the problem of calculating best approximations. The material of this paper will be mainly, but not only, used in developing algorithms for the one-sided and two-sided sided approximation problem.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.4
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• pp.849-862
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• 2011

In this paper, we introduce certain concepts which provide us with a perspective and insight into the generalization of orthogonality with the normalized duality mapping. The material of this paper will be mainly, but not only, used in developing algorithms for the best approximation problem in a Banach space.

• Journal of the Chungcheong Mathematical Society
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• v.32 no.3
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• pp.309-318
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• 2019

We introduce the concepts of double pairwise strongly (r, s)(u, v)-semiopen mappings and double pairwise strongly (r, s)(u, v)-semiclosed mappings, and investigate some of their characteristic properties.

• Communications of Mathematical Education
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• v.25 no.2
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• pp.403-430
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• 2011

The purpose of the study was to investigate how the use of graphing calculators influence on forming students' mathematical concept of algebra, students' mathematical connection, and attitude toward mathematics. First, graphing calculators give instant feedback to students as they make students compare their written answers with the results, which helps students learn equations and linear inequalities for themselves. In respect of quadratic inequalities they help students to correct wrong concepts and understand fundamental concepts, and with regard to functions students can draw graphs more easily using graphing calculators, which means that the difficulty of drawing graphs can not be hindrance to student's learning functions. Moreover students could understand functions intuitively by using graphing calculators and explored math problems volunteerly. As a result, students were able to perceive faster the concepts of functions that they considered difficult and remain the concepts in their mind for a long time. Second, most of students could not think of connection among equations, equalities and functions. However, they could understand the connection among equations, equalities and functions more easily. Additionally students could focus on changing the real life into the algebraic expression by modeling without the fear of calculating, which made students relieve the burden of calculating and realize the usefulness of mathematics through the experience of solving the real-life problems. Third, we identified the change of six students' attitude through preliminary and an ex post facto attitude test. Five of six students came to have positive attitude toward mathematics, but only one student came to have negative attitude. However, all of the students showed positive attitude toward using graphing calculators in math class. That's because they could have more interest in mathematics by the strengthened and visualization of graphing calculators which helped them understand difficult algebraic concepts, which gave them a sense of achievement. Also, students could relieve the burden of calculating and have confidence. In a conclusion, using graphing calculators in algebra and function class has many advantages : formulating mathematics concepts, mathematical connection, and enhancing positive attitude toward mathematics. Therefore we need more research of the effect of using calculators, practical classroom materials, instruction models and assessment tools for graphing calculators. Lastly We need to make the classroom environment more adequate for using graphing calculators in math classes.

• East Asian mathematical journal
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• v.27 no.4
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• pp.381-389
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• 2011

The flexible mathematical thinking - the ability to generate and connect various representations of concepts - is useful in understanding mathematical structure and variation in problem solving. In particular, the flexible mathematical thinking with the inventive mathematical thinking, the original mathematical problem solving ability and the mathematical invention is a core concept, which must be emphasized in all branches of mathematical education. In this paper, the author considered a case of flexible mathematical thinking with an inventive problem solving ability shown by his student via real analysis courses. The case is on the proofs of the equivalences of three different definitions on the concept of limit superior shown in three different real analysis books. Proving the equivalences of the three definitions, the student tried to keep the flexible mathematical thinking steadily.