• Journal of the Chungcheong Mathematical Society
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• v.25 no.4
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• pp.643-653
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• 2012

Let $f\;:\;M\;{\rightarrow}\;M$ be a diffeomorphism on a closed $C^{\infty}$ manifold. Let $\Lambda$ be a transitive set. In this paper, we show that (i) $C^1$-generically, $f$ has the shadowing property on a locally maximal $\Lambda$ if and only if $\Lambda$ is hyperbolic, (ii) f has the $C^1$-stably shadowing property on $\Lambda$ if and only if $\Lambda$ is hyperbolic.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.241-244
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• 2000

In this paper, we investigate performance of OFDM employing macrodiversity selection on a shadowed multipath channel to reduce the effects of long-term shadowing. Three different situations are considered： independent shadowing with equidistant ports, independent shadowing with non-equidistant ports, and correlated shadowing. Numerical results show that OFDM performance is improved as the number of macrodiversity ports increases. In the situation where the user is much closer to certain port(s), performance becomes worse compared to that of the equidistant situation. In addition, as the correlation increases among the ports, the advantage of macrodiversity is reduced.

• Communications of the Korean Mathematical Society
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• v.19 no.4
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• pp.759-764
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• 2004

Let X = {a} ${\cup}$ {$a_{i}$ ${$\mid$}$i $\in$ N} be a subspace of Euclidean space $E^2$ such that $lim_{{i}{\longrightarrow}{$\infty}}a_{i}$ = a and $a_{i}\;{\neq}\;a_{j}$ for $i{\neq}j$. Then it is well known that the space X has no expansive homeomorphisms with the shadowing property. In this paper we show that the set of all expansive homeomorphisms with the shadowing property on the space Y is dense in the space H(Y) of all homeomorphisms on Y, where Y = {a, b} ${\cup}$ {$a_{i}{$\mid$}i{\in}Z$} is a subspace of $E^2$ such that $lim_{i}$-$\infty$ $a_{i}$ = b and $lim_{{i}{\longrightarrow}{$\infty}}a_{i}$ = a with the following properties; $a_{i}{\neq}a_{j}$ for $i{\neq}j$ and $a{\neq}b$.

• Bulletin of the Korean Mathematical Society
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• v.59 no.2
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• pp.319-343
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• 2022

We discuss the notions of positive expansivity, chain transitivity, uniform rigidity, chain mixing, weak specification, and pseudo orbital specification in terms of finite open covers for Hausdorff topological spaces and entourages for uniform spaces. We show that the two definitions for each notion are equivalent in compact Hausdorff spaces and further they are equivalent to their standard definitions in compact metric spaces. We show that a homeomorphism on a Hausdorff uniform space has uniform h-shadowing if and only if it has uniform shadowing and its inverse is uniformly equicontinuous. We also show that a Hausdorff positively expansive system with a Hausdorff shadowing property has Hausdorff h-shadowing.

• Journal of the Chungcheong Mathematical Society
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• v.35 no.3
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• pp.269-275
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• 2022

In this note, we verify that the bounded shadowing property and quasi-hyperbolicity of bounded linear operators on Hilbert spaces are preserved under Aluthge transforms.

• Journal of the Chungcheong Mathematical Society
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• v.23 no.1
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• pp.65-71
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• 2010

Let $\Lambda$ be a transitive set for f. In this paper, we show that if a f-invariant set $\Lambda$ has the $C^{1}$-stably shadowing property, then $\Lambda$ admits a dominated splitting.

• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.613-619
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• 2012

In this paper, we prove that locally maximal transitive set of a $C^1$-generic diffeomorphism is hyperbolic if and only if it is limit weak shadowable.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.4
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• pp.631-638
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• 2011

In this paper, we prove that for $C^1$ generically, if every hyperbolic periodic point in a chain component is uniformly far away from being nonhyperbolic, and it is $C^1$-robustly average shadowable, then the chain component is hyperbolic.

• Journal of Yeungnam Medical Science
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• v.15 no.1
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• pp.151-158
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• 1998

Traditionally posterior shadowing is regarded as a malignant criterion in the evaluation of breast mass by sonogram. But on the basis of our clinical experiences of breast sonogram, we often met a breast mass without posterior shadowing later confirmed breast carcinoma through pathologic examination. For the focus of what character of pathologic breast tissue influence the posterior shadowing in breast sonogram, we analyzed retrospectively the sonographic findings of 26 histologically proven invasive ductal carcinomas. Even though invasive ductal carcinoma is the only one of the many breast cancers, it represents the greater part of breast malignancy. The posterior echo pattern was compared with various histologic characteristics, such as the amount of connective tissue, degree of elastosis, necrosis, gross circumscription, accompanying inflammation, histologic differentiation, and mitotic index. Nine breast masses (35%) demonstrated posterior echo shadowing, while 17 masses (65%) showed enhancement. The tumors with posterior echo shadowing had more abundant connective tissue, increased elastosis, and poorly demarcated margin (p<0.05). Other histologic characteristics are not influence in posterior shadowing with significant in stastically. On the basis of our study, the phenomenon of posterior shadowing by sonogram is difficult to accept as a specific criterion for malignancy. It is only a phenomenon influenced by the amount of connective tissue volume and elastosis.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.4
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• pp.45-54
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• 2001

It is necessary to control security management consistently and respond to an intrusion automatically in order to use the network securely in the single administrative domain. This paper presents a Shadowing Mechanism supporting a dynamic extension of security scheme and proposes an ARTEMIS(Advanced Realtime Emergency Management and Intruder Identification System), which is designed and implemented based on the suggested technique. It is possible for security management system developed on the basis of the Shadowing Mechanism to make all network components working under the same security scheme. It enhances the accuracy of intrusion tracing and automatic response through dynamic extension of space and time for security management.