• Korean Journal of Mathematics
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• v.28 no.3
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• pp.573-585
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• 2020

We introduced the concepts of the generalized accumulation points and the generalized density of a subset of the Euclidean space in [1] and [2]. Using those concepts, we introduce the concepts of the generalized closure, the generalized interior, the generalized exterior and the generalized boundary of a subset and investigate some properties of these sets. The generalized boundary of a subset is closely related to the classical boundary. Finally, we also introduce and study a concept of the thickness of a subset.

• Korean Journal of Mathematics
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• v.17 no.3
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• pp.249-255
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• 2009

In [5], we introduced the concepts of IVF m-preopen sets and IVF m-precontinuous mappings on interval-valued fuzzy minimal spaces. In this paper, we introduce the concept of IVF m-preopen mapping and investigate characterizations for IVF mprecontinuous mappings and IVF m-preopen mappings.

• Korean Journal of Mathematics
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• v.18 no.1
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• pp.37-43
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• 2010

Let D be an integral domain, X be an indeterminate over D, and $N_v=\{f{\in}D[X]{\mid}(A_f)_v=D\}$. In this paper, we introduce the concept of t-locally divided domains, and we then prove that $D[X]_{N_v}$ is a locally divided domain if and only if D is a t-locally divided UMT-domain, if and only if D[X] is a t-locally divided domain.

• Korean Journal of Mathematics
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• v.28 no.2
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• pp.391-403
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• 2020

In this paper, we initiate the concept of almost ζ- contractions via Simulation functions to find fixed points on M- metric spaces, and prove some related fixed points results for such mappings. Moreover an illustration is provided to show the applicability of our obtained results.

• Korean Journal of Mathematics
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• v.28 no.1
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• pp.31-47
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• 2020

In this paper, we discuss in detail some of the properties of the new kind of (∈, ∈ ∨q)-fuzzy ideals in Near-ring. The concept of (∈, ∈ ∨q^δ₀)-fuzzy ideal of Near-ring is introduced and some of its related properties are investigated.

• Communications for Statistical Applications and Methods
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• v.12 no.1
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• pp.253-264
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• 2005

Hader and Park(l978) suggested the concept of slope-rotatability in axial directions for second order response surface designs. In this paper, the moment conditions for slope-rotatability in axial directions are shown and the measures for evaluating slope-rotatability in axial directions are proposed.

• Kyungpook Mathematical Journal
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• v.45 no.1
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• pp.87-87
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• 2005

Using the belongs to relation $({\in})$ and quasi-coincidence with relation (q) between intuitionistic fuzzy points and intuitionistic fuzzy sets, the concept of (${\Phi},\;{\Psi}$)-intuitionistic fuzzy subgroup where ${\Phi},\;{\Psi}$ are any two of {${\in},\;q,\;{\in}{\vee}q,\;{\in}{\wedge}q$} with ${\Phi}\;{\neq}\;{\in}{\wedge}q$ is introduced, and related properties are investigated.

• Kyungpook Mathematical Journal
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• v.45 no.1
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• pp.137-152
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• 2005

We introduce the concept of what we call "regular difference covers" and prove many nonexistence results and provide some new constructions. Although the techniques employed mirror those used to investigate difference sets, the end results in this new setting are quite different.

• Kyungpook Mathematical Journal
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• v.54 no.2
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• pp.211-220
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• 2014

In the present investigation, by making use of the familiar concept of neighborhoods of analytic and multivalent functions, we prove several inclusion relations associated with the (n, ${\delta}$)-neighborhoods of certain subclasses of analytic functions of complex order, which are introduced here by means of the Al-Oboudi derivative. Several special cases of the main results are mentioned.

• Kyungpook Mathematical Journal
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• v.47 no.2
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• pp.221-226
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• 2007

In this note we set forth three possible definitions of the property of "almost commuting with a compact operator" and discuss an old result of W. Arveson that says that every operator on Hilbert space has the weakest of the three properties. Finally, we discuss some recent progress on the hyperinvariant subspace problem (see the bibliography), and relate it to the concept of almost commuting with a compact operator.