• Honam Mathematical Journal
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• v.36 no.4
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• pp.885-893
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• 2014

In this paper, we introduce the concept of a right f-derivation in incline algebras and give some properties of incline algebras. Also, the concept of d-ideal is introduced in an incline algebra with respect to right f-derivations.

• Honam Mathematical Journal
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• v.40 no.1
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• pp.109-124
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• 2018

In this paper, structure of involution ${\Gamma}$-semihypergroup is introduced and some theorems about this concept are stated and proved. The concept of ${\Gamma}$-hyperideal in involution ${\Gamma}$-semihypergroup is defined and some of their properties are studied. Some results on regular ${\Gamma}^*$-semihypergroups and fuzzy ${\Gamma}^*$-semihypergroups are also provided.

• Journal of the Chungcheong Mathematical Society
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• v.18 no.2
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• pp.175-193
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• 2005

In [1], the concept of generalized (${\theta}$, ${\phi}$)-derivations on rings was introduced. In this paper, we introduce the concept of generalized (${\theta}$, ${\phi}$)-derivations on Poisson Banach algebras and of generalizd (${\theta}$, ${\phi}$)-derivations on Jordan Banach algebras, and prove the Cauchy-Rassias stability of generalized (${\theta}$, ${\phi}$)-derivations on Poisson Banach algebras and of generalized (${\theta}$, ${\phi}$)-derivations on Jordan Banach algebras.

• Journal of the Chungcheong Mathematical Society
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• v.28 no.2
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• pp.187-194
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• 2015

The concept of sub-independence is based on the convolution of the distributions of the random variables. It is much weaker than that of independence, but is shown to be sufficient to yield the conclusions of important theorems and results in probability and statistics. It also provides a measure of dissociation between two random variables which is much stronger than uncorrelatedness. Inspired by the excellent work of Jin and Lee (2014), we present certain characterizations of gamma distribution based on the concept of sub-independence.

• Journal of applied mathematics & informatics
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• v.7 no.3
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• pp.1059-1068
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• 2000

In this paper we introduce a new concept of weakly positive upper orthant dependence POD of hitting times of stochastic processes. This concept is weaker than the positively orthant dependent and it is closed under a certain statistical operations of W POD ordering. Examples are given to illustrate these concepts.

• Bulletin of the Korean Mathematical Society
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• v.45 no.3
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• pp.601-606
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• 2008

The purpose of this paper is to introduce and discuss the concept of ${\omega}$-Chebyshev subspaces in Banach spaces. The concept of quasi Chebyshev in Banach space is defined. We show that ${\omega}$-Chebyshevity of subspaces are a new class in approximation theory. In this paper, also we consider orthogonality in normed spaces.

• East Asian mathematical journal
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• v.23 no.2
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• pp.151-158
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• 2007

In this paper we introduce the concept of fuzzy ${\beta}-compact^*$ spaces. Besides giving some interesting properties of fuzzy ${\beta}-compact^*$ spaces we also give a characterization on fuzzy $\beta$-compact spaces by making use of newly introduced concept of fuzzy $\beta$-filters.

• Honam Mathematical Journal
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• v.27 no.1
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• pp.101-113
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• 2005

We define and study a concept of $T_A$-space which is closely related to the generalized Gottlieb group. We know that X is a $T_A$-space if and only if there is a map $r:L(A,\;X){\rightarrow}L_0(A,\;X)$ called a $T_A$-structure such that $ri{\sim}1_{L_0(A,\;X)}$. The concepts of $T_{{\Sigma}B}$-spaces are preserved by retraction and product. We also introduce and study a dual concept of $T_A$-space.

• Journal of the Chungcheong Mathematical Society
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• v.32 no.4
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• pp.393-400
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• 2019

Pajoohesh introduced the concept of k-metric spaces and Hiltzler and Seda defined the concept of metric-like spaces. Recently, Kopperman and Pajoohesh proved a fixed point theorem in complete k-metric spaces for a Lipschitz map with bound. In this paper, we prove a fixed point theorem in complete metric-like spaces for a Lipschitz map with bound.

• Bulletin of the Korean Mathematical Society
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• v.49 no.1
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• pp.99-107
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• 2012

The concept of Hilbert space dissipative norm was introduced in [8] to obtain necessary and sufficient conditions for exponential stability of contraction semigroups. In the present paper we show that the same concept can also be used to derive further properties of contraction semigroups, as well as to characterize strongly stable semigroups that are not exponentially stable.