• Bulletin of the Korean Mathematical Society
• /
• v.48 no.3
• /
• pp.637-646
• /
• 2011

Cho and Kim [4] and Kim [6] introduced the concept of the competition index of a digraph. Cho and Kim [4] and Akelbek and Kirkland [1] also studied the upper bound of competition indices of primitive digraphs. In this paper, we study the upper bound of competition indices of strongly connected digraphs. We also study the relation between competition index and ordinary index for a symmetric strongly connected digraph.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.330-334
• /
• 2000

This paper proposes a new double-connected 3-phase voltage source inverter with improved output voltage waveform. An auxiliary single-phase inverter injects a ripple voltage into the double- connected inverter to convert 12-step operation to 36-step operation. The KVA rating of the output phase-shifting transformer is reduced by employing a harmonic canceling reactor. The whole rectifier-inverter system including the proposed technique is introduced and the experimental results are provided.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.248-251
• /
• 1999

Recently, according to developing industry and life style, power consumption have been increased year after year. Currently these much power demand from power consumer is weakening the allowable power reverse margin in summer. As on of the remedies about this problem, the small scale grid-connected photovoltaic system is considered for auxiliary power source. Generally, grid-connected inverter have a isolation transformer for electrical isolation from utility. This paper propose transformerless system topology an inquiry the validity using simulation.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.346-349
• /
• 1999

This paper proposes a new series-connected diode rectifier which draws sinusoidal input currents. The proposed rectifier system is configured by adding an auxiliary circuit to the conventional 12-pulse series-connected diode rectifier and employing a current injection technique. A low kVA (0.02Po (PU) ) active current source injects a triangular current results in near sinusoidal input current from the utility with less than 1% THD. The resulting system is suitable for high voltage and high power applications. Experimental results is provided from a 220VA rectifier system.

• Journal of the Korean Mathematical Society
• /
• v.40 no.3
• /
• pp.447-460
• /
• 2003

In this paper we study the non-degenerate n-connected canonical domains with n>1 related to the conjecture of S. Bell in [4]. They are connected to the algebraic property of the Bergman kernel and the Szego kernel. We characterize the non-degenerate doubly connected canonical domains.

• Bulletin of the Korean Mathematical Society
• /
• v.55 no.5
• /
• pp.1419-1431
• /
• 2018

Let $f=h+{\bar{g}}$ be a harmonic mapping of the unit disk ${\mathbb{D}}$ with the holomorphic part h satisfying that h is injective and $h({\mathbb{D}})$ is an M-linearly connected domain. In this paper, we obtain the sufficient and necessary conditions for f to be bi-Lipschitz, which is in particular, quasiconformal. Moreover, some distortion theorems are also obtained.

• Journal of applied mathematics & informatics
• /
• v.28 no.3_4
• /
• pp.893-908
• /
• 2010

In this paper we prove the existence of spanning 3-trees in a 3-connected infinite locally finite VAP-free plane graph. Together with the results of Barnette and the author, this yields that every finite or infinite 3-connected locally finite VAP-free plane graph contains a spanning 3-tree.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.455-459
• /
• 1998

In this paper input Series-Output Parallel connected converter configuration for high voltage power conversion applications is proposed and a control method to solve the problems of Input Series-Output Paralles connected converter configuration is introduced. In this configuration snubber circuit or voltage balancing controller that is necessary for the series connection of switching devices is not needed. The effectiveness of this proposed configuration is verified by simulation.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.405-408
• /
• 1998

In this paper, a predictive current control of 12-pulse parallel connected dual converter system with interphase transfromer(IPT) is presented. Firstly, 12-pulse parallel connected dual converter system and the predictive current control of this system is discussed. And the validity of the presented system and the excellence of the predictive current control response is proved through the simyulation and experiment result.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.3 no.2
• /
• pp.258-261
• /
• 2003

The aim of this paper is to introduce the concept $\gamma$-connectedness in fuzzy topological spaces. We also investigate some interre lations between this types of fuzzy connectedness together with the preservation properties under some types of fuzzy continuity. A comparison between some types of connectedness in fuzzy topological spaces is of interest.