• Journal of the Chungcheong Mathematical Society
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• v.8 no.1
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• pp.119-130
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• 1995

I study the extension of the definition of the analytic operator-valued Feynman integral to potentials given by a class of signed measures described in terms of additive functionals associated with regular Dirichlet forms.

• Communications of the Korean Mathematical Society
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• v.12 no.4
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• pp.905-909
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• 1997

A characterization of Hilbert spaces is given in terms of four boundary points and two interior points of the unit sphere.

• Bulletin of the Korean Mathematical Society
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• v.46 no.3
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• pp.489-498
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• 2009

We obtain two new characterizations of separativity of refinement monoids, in terms of comparability-type conditions. As applications, we get several equivalent conditions of separativity for exchange ideals.

• Bulletin of the Korean Mathematical Society
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• v.33 no.1
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• pp.35-38
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• 1996

The aim of this paper is to present a characterization of Hilbert spaces in terms of the lengths of four sides and two diagonals of a parallelogram.

• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.623-632
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• 1997

In this paper, the nonexistence of the global solutions of semilinear wave equations with damping terms in the boundary conditions is investigated.

• East Asian mathematical journal
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• v.19 no.2
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• pp.207-212
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• 2003

Some new characterization of best approximants from level sets of convex functions in normed linear spaces in terms of norm derivatives are given.

• East Asian mathematical journal
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• v.10 no.1
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• pp.25-34
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• 1994

• The Mathematical Education
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• v.55 no.2
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• pp.209-232
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• 2016

This study analyzed the process of steps in a program introducing Renzulli's enrichment triad model and various levels of posing open-ended problems of those who participated in the program for mathematics-gifted elementary students. As results, participants showed their abilities of problem posing related to real life in a program introducing Renzulli's enrichment triad model. From eighteen mathematical responses, gifted students were generally outstanding in terms of producing problems that demonstrated high quality completion, communication, and solvability. Amongst these responses from fifteen open-ended problems, all of which showed that the level of students' ability to devise questions was varied in terms of the problems' openness (varied possible outcomes), complexity, and relevance. Meanwhile, some of them didn't show their ability of composing problem with concepts, principle and rules in complex level. In addition, there are high or very high correlations among factors of mathematical problems themselves as well as open-ended problems themselves, and between mathematical problems and open-ended problems. In particular, factors of mathematical problems such as completion, communication, and solvability showed very high correlation with relevance of the problems' openness perspectives.

• Journal of the Korean Mathematical Society
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• v.37 no.6
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• pp.1007-1019
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• 2000

In this paper, we discuss a uniqueness problem for the Cauchy problem of the Euler equation. W give a sufficient condition on the vorticity to show the uniqueness of a class of generalized solution in terms of the generalized solution in terms o the generalized Besov space. The condition allows the iterated logarithmic singularity to the vorticity of the solution. We also discuss the break down (or blow up) condition for a smooth solution to the Euler equation under the related assumption.

• Communications of the Korean Mathematical Society
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• v.30 no.3
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• pp.277-282
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• 2015

We obtain some conditions for disconnectedness of a topological space in terms of maximal and minimal open sets, and some similar results in terms of maximal and minimal closed sets along with interrelations between them. In particular, we show that if a space has a set which is both maximal and minimal open, then either this set is the only nontrivial open set in the space or the space is disconnected. We also obtain a result concerning a minimal open set on a subspace.