• Korean Journal of Mathematics
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• v.16 no.4
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• pp.495-498
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• 2008

Every totally disconnected space is hereditarily disconnected. In this note, we provide an example of a hereditarily disconnected which is not a totally disconnected space. We further provide an example that not homogeneous space is the product of a totally disconnected and a connected.

• Communications of the Korean Mathematical Society
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• v.34 no.1
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• pp.351-359
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• 2019

In this paper, we introduce a modification of extremally disconnected spaces which is said to be m-extremally disconnected. And we obtain many characterizations of m-extremally disconnected spaces. The concepts of ${\ast}$-extremally disconnected spaces, ${\ast}$-hyperconnected spaces, and generalized hyperconnectedness are as examples for this paper.

• Communications of the Korean Mathematical Society
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• v.21 no.2
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• pp.347-353
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• 2006

In this paper, we show that if the minimal basically disconnected cover ${\wedge}X_\imath\;of\;X_\imath$ is given by the space of fixed a $Z(X)^#$-ultrafilters on $X_\imath\;(\imath=1,2)\;and\;{\wedge}X_1\;{\times}\;{\wedge}X_2$ is a basically disconnected space, then ${\wedge}X_1\;{\times}\;{\wedge}X_2$ is the minimal basically disconnected cover of $X_1\;{\times}\;X_2$. Moreover, observing that the product space of a P-space and a countably locally weakly Lindelof basically disconnected space is basically disconnected, we show that if X is a weakly Lindelof almost P-space and Y is a countably locally weakly Lindelof space, then (${\wedge}X\;{\times}\;{\wedge}Y,\;{\wedge}_X\;{\times}\;{\wedge}_Y$) is the minimal basically disconnected cover of $X\;{\times}\;Y$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.104-110
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• 2011

There are over 30[%] of electric fires in Korea happened at wire or wiring devices. For its prevention many safety devices are set up electric equipments. These safety devices are not working in a rated current's condition of electric equipment. But when wire is partially disconnected, electric fire is able to be happened even though current is smaller than a rated current value. This paper studied thermal characteristics and fire ability when wire in plug is partially disconnected. The experiment is progressed a method that inner wire of plug is partially disconnected and after that current that is less than a rated current is flowed. As the result, heating occurred in near of partially disconnected wire makes that outer sheath is melted, plug cover is carbonized, and even sometimes wire is fused. And results of analysis of thermal image of partially disconnected wire happened in plug, it shows a difference to heating distribution and temperature appeared surface of plug depend on a progress of a partially disconnected wire.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3B
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• pp.202-211
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• 2002

Because wireless links are subject to disturbances and failures, it is important to support disconnected operations in mobile computing. Many schemes have been proposed to support the efficient disconnected operations. In this paper, we analyze and measure the computation time including disconnected operations to evaluate the performance of mobile computing on error prone wireless links. Mobile computation consists of three states: data hoarding, disconnected operation, and block states. We estimate the computation time using various parameters; error rate and recovery rate of wireless link, hoarding overhead, logging overhead, and reintegration overhead, etc. We can choose efficient strategies for disconnected operations and predict the performance using the results of this analysis.

• Journal of the Korean Mathematical Society
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• v.34 no.4
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• pp.1009-1018
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• 1997

Observing that for any $\beta_c$-Wallman functor $A$ and any Tychonoff space X, there is a cover $(C_1(A(X), X), c_1)$ of X such that X is $A$-disconnected if and only if $c_1 : C_1(A(X), X) \longrightarrow X$ is a homeomorphism, we show that every Tychonoff space has the minimal $A$-disconnected cover. We also show that if X is weakly Lindelof or locally compact zero-dimensional space, then the minimal G-disconnected (equivalently, cloz)-cover is given by the space $C_1(A(X), X)$ which is a dense subspace of $E_cc(\betaX)$.

• East Asian mathematical journal
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• v.23 no.2
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• pp.159-174
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• 2007

In this paper, the concepts of pairwise fuzzy $G_{\delta}$-connected spaces and pairwise fuzzy $G_{\delta}$-extremally disconnected spaces are introduced. The concept of pairwise fuzzy $G_{\delta}$-basically disconnected spaces is defined. Characterizations of the above spaces are given besides giving several examples. Interrelations among the spaces introduced are discussed and some relevant counter examples are given.

• East Asian mathematical journal
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• v.24 no.3
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• pp.213-221
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• 2008

In this paper, a new class of fuzzy topological spaces called ordered fuzzy pre-extremally disconnected spaces is introduced. Tietze extension theorem for ordered fuzzy pre-extremally disconnected spaces has been discussed as in [9] besides proving several other propositions and lemmas.

• Journal for History of Mathematics
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• v.16 no.1
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• pp.73-78
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• 2003

Observing that if f: $Y{\leftrightarro}$Χ is a covering map and Χ is a countably locally weakly Lindelof space, then Y is countably locally weakly Lindelof and that every dense countably weakly Lindelof subspace of a basically disconnected space is basically disconnected, we show that for a countably weakly Lindelof space Χ, its minimal basically disconnected cover ${\bigwedge}$Χ is given by the filter space of fixed ${\sigma}Ζ(Χ)^#$- ultrafilters.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.691-699
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• 2008

In the design of a foundation, settlement of the foundation may exceed allowable design criteria even with a competent bearing stratum. In such a case, a piled-raft foundation system may be adopted using piles as settlement reducing component. In this paper, Disconnected Piled Raft Foundation (DPRF) system, which installs disconnected piles underneath the raft and uses the piles as ground reinforcements, is studied as a cost effective design method against the classical piled-raft foundation system. To this end, large size loading tests were carried out on weathered ground changing area replacement ratio and length of piles. The results indicated that the settlement of the reinforced ground was reduced by 34~87% and the allowable bearing pressure increased by 70% on average from those of the unreinforced original ground, respectively. The correlating formula between the area replacement ratio and the load bearing ratio of piles were derived from the test results and numerical analysis. From the correlation, a design method determining the size and the quantity of the disconnected piles to enhance the bearing capacity of original ground to the desired value was proposed based on one inch settlement criteria.