• Honam Mathematical Journal
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• v.26 no.2
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• pp.237-246
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• 2004

In this paper, three kinds of minimal digital pseudotori $DT_6$, $DT^{\prime}_{18}$, $DT^{{\prime}{\prime}}_{26}$, which are derived from the minimal simple 4- and 8-curves, $MSC_4$ and $MSC^{\prime}_8$, are shown and are proved not to be digitally ${\kappa}$-homotopy equivalent to each other, where ${\kappa}{\in}\{6,\;18,\;26\}$. Furthermore, the digital topological properties of the minimal digital ${\kappa}$-pseudotori are investigated in the digital homotopical point of view, where ${\kappa}{\in}\{6,\;18,\;26\}$.

• Kyungpook Mathematical Journal
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• v.48 no.3
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• pp.487-493
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• 2008

A. Di Nola & S.Sessa [8] showed that two compact spaces X and Y are homeomorphic iff the MV -algebras C(X, I) and C(Y, I) of continuous functions defined on X and Y respectively are isomorphic. And they proved that A is a semisimple MV -algebra iff A is a subalgebra of C(X) for some compact Hausdorff space X. In this paper, firstly by use of functorial argument, we show these characterization theorems. Furthermore we obtain some other functorial results between topological spaces and MV -algebras. Secondly as a classical problem, we find a necessary and sufficient condition on a given residuated l-monoid that it is segmenently embedded into an l-group with order unit.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1552-1557
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• 2015

The paper unleashes a new idea to arrive at reduced switch count topological structures configured in the form of a matrix for a cascaded Multi level inverter (CMLI). The theory encircles to minimize the number of switches involved in the conduction path and there from acclaim reduced input current distortion, lower switching losses and electromagnetic interference. The focus extends to standardize the number of power devices required for reaching different levels of output voltage from the same architecture. It includes appropriate pulse width modulation (PWM) strategy to generate firing pulses and ensure the desired operation of the power modules. The investigative study carries with it MATLAB based simulation and experimental results obtained using suitable prototypes to illustrate the viability of the proposed concept. The promising nature of the performance projects a new dimension in the use of single phase MLIs for renewable energy related applications.

• Communications of the Korean Mathematical Society
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• v.9 no.4
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• pp.945-950
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• 1994

Although the study of the limit points of discrete groups of M$\ddot{o}$bius transformations has been a fertile area for many decades, there are some very natural topological properties of the limit points which appear not to have been previously examined. Let $\Gamma$ be a nonelementary discrete group of hyperbolic isometries acting on the Poincare disc $B^m, m \geq 2$, and let $p \in \partial B^m$ be a limit point of $\Gamma$. By a neighborhood of p, we will always mean an open neighborhood of p in $\partial B^m$.

• Journal of the Korean Mathematical Society
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• v.54 no.2
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• pp.399-415
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• 2017

Given a topological space X and a non-negative integer k, we study the self-homotopy equivalences of X that do not change maps from X to n-sphere $S^n$ homotopically by the composition for all $n{\geq}k$. We denote by ${\varepsilon}^{\sharp}_k(X)$ the set of all homotopy classes of such self-homotopy equivalences. This set is a dual concept of ${\varepsilon}^{\sharp}_k(X)$, which has been studied by several authors. We prove that if X is a finite CW complex, there are at most a finite number of distinguishing homotopy classes ${\varepsilon}^{\sharp}_k(X)$, whereas ${\varepsilon}^{\sharp}_k(X)$ may not be finite. Moreover, we obtain concrete computations of ${\varepsilon}^{\sharp}_k(X)$ to show that the cardinal of ${\varepsilon}^{\sharp}_k(X)$ is finite when X is either a Moore space or co-Moore space by using the self-closeness numbers.

• Bulletin of the Korean Mathematical Society
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• v.41 no.3
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• pp.541-557
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• 2004

In this paper we prove the Hyers-Ulam-Rassias stability by considering the cases that the approximate remainder ${\varphi}$ is defined by (x * y) ＋ (x * $y^{-1}$) - 2 (x) - 2 (y) =<${\varphi}$(x,y), (x*y*z)＋ (x)＋ (y)＋ (z)－ (x*y)－ (y*z)－ (z*x)＝${\varphi}$(x, y, z), where (G,*) is a group, X is a real or complex Hausdorff topological vector space, and is a function from G into X.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1598-1601
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• 1987

This paper proposes a new set of topological features (primitives) for use with a syntactic recognizer for high-accuracy recognition of printed alphanumeric characters. The recognition is accomplished on nine character groups, where each group has different combinations of four feature points. A skeleton enhancement eliminating isolated points and smoothing irregular points is developed. The tree automata processed in parallel enables the realization of high-recognition speeds and font-type independent recognition. The proposed character recognition system is tested for alphanumeric character fonts of dot matrix printer and plotter using IBM-PC/XT.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.33-43
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• 2004

A carbon budget model was constructed and analyzed for the Bangjukpo surf zone ecosystem in southern Korea by using the NETWRK. The model consists of 11 living and 1 non-living groups. Using boxes and arrows, a topological map was created to depict biomasses of each group and exchange rates between them. The system includes primary producers of phytoplankton and benthic algae, primary consumers of particle feeding zooplankton, carnivorous zooplankton, meiobenthos, malacostracans and bivalves, and top consumers of detrivorous, omnivorous, carnivorous and piscivorous fishes. The surf zone ecosystem was analyzed by means of network analysis, showing total system throughput of $574\;gCm^{-2}yr^{-1},$ development capacity of $1,876\;gCm^{-2}yr^{-1},$ ascendancy value of $768\;gCm^{-2}yr^{-1},$ Finn cycling index of $4.4\%$ and internal relative ascendancy of $27\%.$ These results were compared with similar data from other systems.

• Bulletin of the Korean Mathematical Society
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• v.31 no.2
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• pp.167-172
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• 1994

For a given $C^{*}$-dynamical system (A, G, .alpha.) with a G-simple $C^{*}$-algebra A (that is A has no proper .alpha.-invariant ideal) many authors have studied the simplicity of a $C^{*}$-crossed product A $x_{\alpha{r}}$ G. In [1] topological freeness of an action is shown to guarantee the simplicity of the reduced $C^{*}$-crossed product A $x_{\alpha{r}}$ G when A is G-simple. In this paper we investigate the pure infiniteness of a simple $C^{*}$-crossed product A $x_{\alpha}$ G of a purely infinite simple $C^{*}$-algebra A and a topologically free action .alpha. of a finite group G, and find a sufficient condition in terms of the action on the spectrum of the multiplier algebra M(A) of A. Showing this we also prove that some extension of a topologically free action is still topologically free.

• Communications of the Korean Mathematical Society
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• v.23 no.2
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• pp.257-268
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• 2008

Let G and K be compact subgroups of orthogonal groups and $0{\leq}r<x<{\infty}$. We prove that every topological fiber bundle over a definable $C^r$ manifold whose structure group is K admits a unique strongly definable $C^r$ fiber bundle structure up to definable $C^r$ fiber bundle isomorphism. We prove that every G vector bundle over an affine definable $C^rG$ manifold admits a unique strongly definable $C^rG$ vector bundle structure up to definable $C^rG$ vector bundle isomorphism.