• 대한수학회논문집
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• 제11권3호
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• pp.797-805
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• 1996

We provide a new proof of the following fact using least area surfaces : If the fundamental group of a $P^2$-irreducible closed 3-manifold M contains a finitely generated nontrivial normal subgroup of infinite index, then M has a finite cover which is a closed surface bundle over $S^1$ , unless N is free.

• 충청수학회지
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• 제19권2호
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• pp.153-158
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• 2006

In this paper, we present an elementary proof for the existence of almost periodic solutions of linear nonhomogeneous difference systems.

• 대한수학회논문집
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• 제10권2호
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• pp.471-482
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• 1995

We give a simple unified proof of various characterizations of discrete classical orthogonal polynomials including two new ones.

• 한국보건교육건강증진학회:학술대회논문집
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• 한국보건교육건강증진학회 2009년도 추계학술대회 자료집
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• pp.269-269
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• 2009

• East Asian mathematical journal
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• 제16권2호
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• pp.169-174
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• 2000

We give an easy proof that ${\phi}(z)=\frac{z^2_1}{1-z^2_2}$ induces the bounded composition operator $C_{\phi}:\mathcal{B}{\rightarrow}{\bigcap}H^p(B_2)$ defined by $C_{\phi}f=f\;o\;{\phi}$.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제4권2호
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• pp.111-113
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• 1997

A simple proof for the special case of the McMillan and Pommerenke Theorem on the asymptotic values of meromorphic functions without Koebe arcs is derived from the author's result on the boundary behavior of meromorphic functions without Koebe arcs.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제22권1호
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• pp.13-23
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• 2015

We introduce a decomposition on a symplectic subspace determined by symplectic structure and study its properties. As a consequence, we give an elementary proof of the deformation of the Grassmannians of symplectic subspaces to the complex Grassmannians.

• 대한수학회지
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• 제39권3호
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• pp.439-460
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• 2002

We prove the multiplicity of ordered positive radial solutions for a semilinear elliptic problem defined on an exterior domain. The key argument is to prove the existence of the third solution in presence of two known solutions. For this, we obtain some partial results related to three solutions theorem for certain singular boundary value problems. Proof are mainly based on the upper and lower solutions method and degree theory.

• East Asian mathematical journal
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• 제24권1호
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• pp.97-103
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• 2008

New fixed point theorems for permissible maps between $Fr{\acute{e}}chet$ spaces are presented. The proof relies on index theory developed by Dzedzej and on viewing a $Fr{\acute{e}}chet$ space as the projective limit of a sequence of Banach spaces.

• Kyungpook Mathematical Journal
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• 제52권3호
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• pp.299-306
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• 2012

We will give a new proof of the Lebesgue-Radon-Nikodym theorem with respect to weighted p-adic q-measure on $Z_p$, using Mahler expansion of continuous functions, studied by the authors in 2012. In the special case, q = 1, we can derive the same result as in Kim, 2012, Kim et al, 2011.