• Kyungpook Mathematical Journal
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• 제49권3호
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• pp.425-433
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• 2009

In this paper, we give the internal characterizations of compact-covering s-(resp., ${\pi}$-)images of locally separable metric spaces. As applications of these results, we obtain characterizations of compact-covering quotient s-(resp., ${\pi}$-)images of locally separable metric spaces.

• Korean Journal of Mathematics
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• 제10권1호
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• pp.19-23
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• 2002

Let X be a Banach space satisfying Opial's condition, C a weakly compact convex subset of $X,F:C{\rightarrow}X$ a nonexpansive map, and let $G:C{\rightarrow}X$ be a compact and demiclosed map. We prove that F + G has a fixed point in C if $F+G:C{\rightarrow}X$ is a weakly inward map.

• 대한수학회보
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• 제35권4호
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• pp.683-687
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• 1998

Suppose X is a subspace of $(\sum_{n=1} ^{\infty} X_n)_{c_0}$, dim $X_n<{\infty}$, which has the metric compact approximation property. It is proved that if Y is a Banach space of cotype q for some $2{\leq}1<{\infty}$ then K(X,Y) is an M-ideal in L(X,Y).

• 대한수학회보
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• 제54권4호
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• pp.1229-1240
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• 2017

This paper presents a systematic study of the abstract harmonic analysis over spaces of complex measures on homogeneous spaces of compact groups. Let G be a compact group and H be a closed subgroup of G. Then we study abstract harmonic analysis of complex measures over the left coset space G/H.

• 대한수학회보
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• 제55권1호
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• pp.1-8
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• 2018

In this paper, we study some topological structure of a compact domain in ${\mathbb{R}}^n$ in terms of the curvature conditions and develop a geometric inequality involving the volume and the integral of mean curvatures over the boundary of the compact domain.

• Kyungpook Mathematical Journal
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• 제47권2호
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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.

• Journal of applied mathematics & informatics
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• 제14권1_2호
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• pp.423-427
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• 2004

For any completely regular Hausdorff space weighted operator on $C_{b}(X)$ is not necessarily compact. In this paper we find both necessary and sufficient conditions for a weighted operator on $C_{b}(X)$ to be compact. And known results in $uC_{\Phi}$ are shown to emerge as special cases.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2005년도 춘계학술대회 학술발표 논문집 제15권 제1호
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• pp.170-173
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• 2005

We note that Jang et at. studied closed set-valued Choquet integrals with respect to fuzzy measures. In this paper, we consider Choquet integrals of compact set-valued functions, and prove some properties of them. In particular, using compact set-valued functions, instead of interval valued we investigate characterization of compact set-valued Choquet integrals.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.327-330
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• 2003

A novel compact circular polarization operation of the microstrip antenna with four-slits and T-slits is proposed. The mechanism for compact size antenna is investigated with the behavior of the currents on the radiating patch. The equivalent surface current path due to the slits is lengthened, reducing the resonant frequency at a fixed patch size. The proposed compact CP design can have an antenna size reduction of about 33 ∼ 45％ as compared to the conventional microstrip antenna. Details of the experimental and measured results are presented and analysed.

• 호남수학학술지
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• 제22권1호
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• pp.47-52
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• 2000

We determine the Shilov and Choquet boundaries and the set of peak points of Lipschitz algebras $Lip(X,\;{\alpha})$ for $0<{\alpha}{\leq}1$, and $lip(X,\;{\alpha})$ for $0<{\alpha}<1$, on a compact metric space X. Then, when X is a compact subset of $\mathbb{C}^n$, we define some subalgebras of these Lipschitz algebras and characterize their Shilov and Choquet boundaries. Moreover, for compact plane sets X, we determine the Shilove boundary of them. We also determine the set of peak points of these subalgebras on certain compact subsets X of $\mathbb{C}^n$.