• Kyungpook Mathematical Journal
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• v.49 no.3
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• pp.425-433
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• 2009

In this paper, we give the internal characterizations of compact-covering s-(resp., ${\pi}$-)images of locally separable metric spaces. As applications of these results, we obtain characterizations of compact-covering quotient s-(resp., ${\pi}$-)images of locally separable metric spaces.

• Kyungpook Mathematical Journal
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• v.33 no.2
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• pp.221-230
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• 1993

• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.365-374
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• 1995

On a compact manifold without conjugate points, the volume entropy can be obtained as the average mean curvature of the horospheres in the universal covering space. In the case when the volume entropy is zero, we prove that the universal covering space is diffeomorphic to a product space with a line factor. This fact can be considered as a surporting evidence for the Mane's conjecture, which claims the flatness of the mainfold.

• Journal of the Korean Mathematical Society
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• v.53 no.2
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• pp.263-286
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• 2016

We discuss relations between Galois coverings of compact Riemann surfaces and their Jacobi varieties. We prove a theorem of a kind of Galois correspondence for Abelian subvarieties of Jacobi varieties. We also prove a theorem on the sets of points in Jacobi varieties fixed by Galois group actions.

• Korean Journal of Mathematics
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• v.25 no.1
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• pp.61-70
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• 2017

In this paper, we introduce the concept of statistically sequentially quotient map which is a generalization of sequence covering map and discuss the relation with covering maps by some examples. Using this concept, we give an affirmative answer for a question by Fucai Lin and Shou Lin.

• Bulletin of the Korean Mathematical Society
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• v.40 no.4
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• pp.723-731
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• 2003

In this paper, we study topological operations of iterated star covering properties, i.e., subspaces, products, and images and preimages of iterated starcompact spaces.

• Bulletin of the Korean Mathematical Society
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• v.39 no.2
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• pp.347-357
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• 2002

In this paper, we study the concepts of isocompactness and cl-isocompactness. We generalize a pure space defined by Arhangelskii and get some results on initially K-compact spaces. We also consider open problems related to isocompactness and cl-isocompactness.

• Journal of applied mathematics & informatics
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• v.7 no.1
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• pp.335-346
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• 2000

This paper discusses the relation of fuzzy sets satisfying some types of fuzzy covering properties. We give some characterizations of such fuzzy sets and investigate a few properties.

• The Pure and Applied Mathematics
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• v.18 no.3
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• pp.261-268
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• 2011

For a compact Hausdorff space X with its p-fold covering map ${\sigma}$, we construct its corresponding topological groupoid ${\Gamma}$, and show that there is a strong relation between the dynamical structures of (X, ${\sigma}$) and the groupoid structures of ${\Gamma}$.

• Communications of the Korean Mathematical Society
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• v.8 no.4
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• pp.755-766
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• 1993