• Journal of the Chungcheong Mathematical Society
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• v.22 no.1
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• pp.101-116
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• 2009

In 1940 S.M. Ulam proposed the famous Ulam stability problem. In 1941 D.H. Hyers solved the well-known Ulam stability problem for additive mappings subject to the Hyers condition on approximately additive mappings. In this paper we improve results for Jensen type mappings and establish new theorems about the Ulam stability of additive and alternative Jensen type mappings.

• Journal for History of Mathematics
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• v.18 no.1
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• pp.75-84
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• 2005

In this paper, we know the historical background in group representations and prove the properties such that a finite group G has non-trivial abelian normal subgroup in some condition for the irreducible character G and prove the properties of product of irreducible characters of finite groups.

• Journal of applied mathematics & informatics
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• v.7 no.1
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• pp.125-137
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• 2000

A solution of the findpath problem in which a moving object in required to avoid moving obstacles and move to the designated target in the plane is porcided via the second method of Lyapunov. This paper presents an new control designed by a family of piecewise Lyapunov functions to solve a findpath problem and gives some simultion results of that.

• Journal of applied mathematics & informatics
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• v.32 no.3_4
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• pp.455-464
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• 2014

We establish some new criteria for the oscillation of mth order nonlinear difference equations. We study the case of strongly superlinear and the case of strongly sublinear equations subject to various conditions. We also present a sufficient condition for every solution to be asymptotic at ${\infty}$ to a factorial expression $(t)^{(m-1)}$.

• Journal of the Korean Mathematical Society
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• v.43 no.1
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• pp.133-145
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• 2006

We study Riemannian or pseudo-Riemannian manifolds which admit a closed conformal vector field. Subject to the condition that at each point $p{\in}M^n$ the set of conformal gradient vector fields spans a non-degenerate subspace of TpM, using a warped product structure theorem we give a complete description of the space of conformal vector fields on arbitrary non-Ricci flat Einstein spaces.

• Kyungpook Mathematical Journal
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• v.50 no.3
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• pp.419-431
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• 2010

A low-order finite element preconditioner is analyzed for a cubic spline collocation method which is used for discretizations of coupled elliptic problems derived from an optimal control problrm subject to an elliptic equation. Some numerical evidences are also provided.

• Korean Journal of Mathematics
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• v.14 no.1
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• pp.113-123
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• 2006

The arches may buckle in a symmetrical snap-through mode or in an asymmetry bifurcation mode if the load reaches a certain value. Each bifurcation curve develops as pressure increases. The governing equation is derived according to the bending theory. The balance of forces provides a nonlinear equilibrium equation. Bifurcation theory near trivial solution of the equation is developed, and the buckling pressures are investigated for various spring constants and opening angles.

• Journal for History of Mathematics
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• v.11 no.1
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• pp.27-35
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• 1998

As Chinese philosophy has developed by commentary for the original texts, the Nine Chapters has been greatly improved by the commentary given by Liu Hui and it was transformed from an arithmetic text to Mathematics. Comparing his commentary and Chinese philosophical development up to his date, we conclude that Liu Hui was able to make such a great leap by his thorough understanding of philosophical development.

• Journal for History of Mathematics
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• v.18 no.1
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• pp.85-92
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• 2005

We review the well known analogizes between variations and harmonic maps. Second section contains rapid summary of the harmonic maps. In the third section we establish some basic properties of the Laplacian on Sphere. In particular we compute its spectrum and eigenfunctions.

• Bulletin of the Korean Mathematical Society
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• v.33 no.1
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• pp.135-170
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• 1996

Recently many people have studied the Sobolev orthogonal polynomials, that is, polynomials which are orthogonal relative to a symmetric bilinear form $\phi(\cdot,\cdot)$ defined by $$ (1.1) $\phi(p,q) := (p,q)_N = \sum_{k=0}^{N} \int_{R}p^(k) (x)q^(k) (x) d\mu_k, $$ where each $d\mu_k$ is a signed Borel measure on the real line $R$ with finite moments of all orders. For the brief history on this subject, we refer to the survey article Ronveaux [13] and Marcellan and et al [10].