• Bulletin of the Korean Mathematical Society
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• v.34 no.3
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• pp.447-457
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• 1997

Let A be a $C^*$-algebra and $A^**$ its enveloping von Neumann algebra. Pedersen and Akemann developed four concepts of lower semicontinuity for elements of $A^**$. Later, Brown suggested using only three classes: strongly lsc, middle lsc, and weakly lsc. In this paper, we generalize the concept of weak semicontinuity [1, 3] to the case of unbounded operators affiliated with $A^**$. Also we consider the generalized version of the conditions of the Brown's theorem [3, Proposition 2.2 & 3.27] for unbounded operators.

• Journal of the Chungcheong Mathematical Society
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• v.16 no.1
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• pp.49-60
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• 2003

In this note, we introduce the concept of the extremal length of a curve family in the complex plane and apply the extremal length to the boundary behavior of analytic functions. We consider some geometric applications of extremal length and establish applications connected with the logarithmic capacity.

• Journal of the Chungcheong Mathematical Society
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• v.20 no.2
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• pp.183-190
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• 2007

In this paper, we will introduce the noetherian quotients in R-groups, and then investigate the related substructures of the near-ring R and G and the R-group G. Also, applying the annihilator concept in R-groups and d.g. near-rings, we will survey some properties of the substructures of R and G in monogenic R-groups and faithful R-groups.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.4
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• pp.691-702
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• 2013

We introduce the concepts of double bitopological spaces as a generalization of intuitionistic fuzzy topological spaces in $\check{S}$ostak's sense and Kandil's fuzzy bitopological spaces. Also we introduce the concept of (${\tau}^{{\mu}{\gamma}}$, $U^{{\mu}{\gamma}}$)-double (r, s)(u, v)-semiopen sets and double pairwise (r, s)(u, v)-semicontinuous mappings in double bitopological spaces and investigate some of their characteristic properties.

• Journal of the Chungcheong Mathematical Society
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• v.4 no.1
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• pp.75-84
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• 1991

In this paper, we introduce the concept of the fibrewise convergence space as a generalization of both the notion of fibrewise topology and that of convergence. Furthermore we observe the adjoint ness and Galois correspondence between the category of fibrewise topological spaces and the category of fibrewise convergence spaces. Finally we investigate the limit and colimit structures in these categories.

• Honam Mathematical Journal
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• v.34 no.4
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• pp.571-584
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• 2012

In this study, we investigate the concept of zero-divisor graphs of multiplication modules over commutative rings as a natural generalization of zero-divisor graphs of commutative rings. In particular, we study the zero-divisor graphs of the module $\mathbb{Z}_n$ over the ring $\mathbb{Z}$ of integers, where $n$ is a positive integer greater than 1.

• Honam Mathematical Journal
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• v.34 no.4
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• pp.559-570
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• 2012

We construct a new definition of a base for ordinary smooth topological spaces and introduce the concept of a neighborhood structure in ordinary smooth topological spaces. Then, we state some of their properties which are generalizations of some results in classical topological spaces.

• Honam Mathematical Journal
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• v.28 no.1
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• pp.57-67
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• 2006

we apply the hyperstructures to BCC-algebras, and introduce the concept of a hyper BCC-algebra which is a generalization of a BCC-algebra, and investigates some related properties. We also introduce the notion of a hyper BCC-subalgebra, BCC-scalar element and a hyper BCC-ideal, and discuss related properties.

• Honam Mathematical Journal
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• v.28 no.1
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• pp.1-22
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• 2006

First, we obtain some results of intuitionistic fuzzy congruences on a regular semigroups contained in ($XH,\;XH^c$). Secondly, we introduce the concept of intuitionistic fuzzy idempotent separating congruences on a semigroup and investigate some of it's properties.

• Honam Mathematical Journal
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• v.35 no.3
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• pp.525-540
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• 2013

We introduce the concept of level subgroups of an interval-valued fuzzy subgroup and study some of its properties. These level subgroups in turn play an important role in the characterization of all interval-valued fuzzy subgroup of a prime cyclic group.