• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.217-224
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• 2013

This paper presents a diagnostic method for a sparse matrix converter that detects faults in any single switch or a pair of switches. The sparse matrix converter is functionally equivalent to the standard matrix converter but has a reduced number of switches. The proposed diagnostic method is based in the measurement of input and output currents. The currents have respective characteristic according to the location of faulty switches. This method not only detects the switches of open-circuit fault but identifies the location of the faulty switching devices without complicated calculations. The simulation and experimental results verify that, based on the proposed method, the fault of sparse matrix converter can be easily and fast detected.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.12
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• pp.1-11
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• 1991

Multi rate circuit switching ISDN which assumes a star topology consisting of LANs(local area networks) interconnected through a backbone MAN (metropolitan area network) is considered. The stations are classified into two categories data and voice stations they are characterized by different arrival rate and session-length (holding time) statistics. We first model the data and voice terminals as finite-source stations and derive analytically exact expressions for the end-to-end blocking probabilities. For more exact evaluation, these probabilities are calculated in terms of three components:circuit blocking probability, destination busy probability and concurrent busy probability. For large size systems, we develop an develop an iterative algorithm that provides a computationally efficient and fast method for the calculation of the end-to-end blocking probabilities.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.78-80
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• 2006

A new low-cost asymmetric current-fed energy-recovery circuit (ERC) for a plasma display panel (PDP) is proposed. LC resonant circuit biased by $V_s/2$ and composed of single switch is used as ERC on both sides of the PDP, slow discharging and fast charging times can be employed, and inductor currents are built up before the PDP is charged and discharged. Therefore, it features a low cost, fully charged/discharged PDP, zero voltage switching (ZVS), low electromagnetic interference (EMI), low current stress, no severe voltage notch, and high energy-recovery capability.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2597-2600
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• 1999

Semiconductor devices can be series stacked for the application of high voltage switching. It can provide high reliability and long lifetime by the safe design with a reasonable margin. The equal voltage distribution at solid-state switches in series should be guaranteed. Static and dynamic voltage division, over current protection must be considered carefully in the design stage. A fast switching thyristor is a good candidate for the high power pulse applications. A high voltage switching module is designed and tested. Its specifications are working voltage of 70 kV, switching pulse width of 120${\mu}s$, peak switching current of 220A, maximum repetition rate of 200pps. The module can be series connected to get higher working voltage. This paper presents the design details and the test results are compared with expected circuit simulations.

• 전기의세계
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• v.28 no.12
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• pp.41-45
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• 1979

Improvement of power factor is achieved by reactive-current compensation, connecting power condenser to the circuit. This paper describes a method of reactive-current compensation, employing thyristor switching of capacitor banks without any breaker. This method reduces supply transients to the minimum by means of connecting condenser, because thyristor is triggered at zero point in condenser current. The reactive current detection and the experimental system to trigger thyristor at appropriate moment are given. IThe results show the fast reactive-current compensation on the condition of minimum transient.

• Journal of Power Electronics
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• v.5 no.4
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• pp.257-263
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• 2005

This paper describes the development and testing results of a high density High Voltage Power Supply (HVPS) that drives microwave Traveling Wave Tubes (TWTs) of phased array transmitters for airborne EW systems. The HVPS is designed to consist of a number of modules connected in series. Among them, especially, the high-density pulse transformer module including the resonant circuit is newly designed to make the HVPS much more reliable. In addition, this paper describes the development of high voltage solid-state modulation using fast switching devices (FETs) and also represents the test results of a modulator module.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.72-78
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• 2008

The speed variation of SRM is fulfilled throughout a transition from chopping control to single pulse operation. (i,e., low speed to high speed operation). It is unsatisfied with performance at all operational regimes. In this paper, the operational performance of SRM can be improved by using current hysteresis control method. This method maintains a generally flat current waveform. At the high speed, the current chopping capability is lost due to the development of the back-EMF. Therefore SRM operates in single pulse mode. By using zero-current switching and zero-voltage switching technique, the stress of power switches can be reduce in chopping mode. When the commutation from one phase winding to another phase winding, the current can be zero as fast as possible in this period because several times negative voltage of DC-source voltage produce in phase winding. This paper is compared to performance based on conventional C-dump converter topology and the proposed resonant C-dump converter topology. Simulation and experimental results are presented to verify the effectiveness of the proposed circuit.

• Progress in Superconductivity and Cryogenics
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• v.19 no.3
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• pp.49-53
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• 2017

The superconducting magnets have a large inductance as well as high operating current. Therefore, mega-joule scale energy can be stored in the magnet. The energy stored in the magnet is sufficient to damage the magnet when a quench occurs. Quench heater and dump resistor can be used to protect the magnet. However, using quench heater to create quench resistors through heat transfer can be slower than instantly switching resistors. Also, electrical short, overheating and breakdown can occur due to quench heater. Moreover, the number of dump resistor should be limited to avoid large terminal voltage. Therefore, in this paper, we propose a quench protection method for extracting the energy stored in a magnet by charging and discharging energy through a capacitor switching without increasing resistance. The simulation results show that the proposed system has a faster current decay within the allowable voltage level.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.55-65
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• 2004

ATM was recommended by the ITU and ATM Forum as a means of transportation for B-ISDN. At this time, due to the comprehensive mature of ATM protocol, ATM has been adapted as the backbone system for carrying Internet traffi $c^{[1,2,3,4]}$. But major conceptsregarding the ATN protocol will be used on future technology. This paper presents preventive congestion control mechanisms for detecting HTR(Hard-To Reach) code in ATM systems, in particular for an improved HTR call registration method using network signaling information will discussed. In high speed circuit switching system environments, a fast HTR control mechanism is necessary. We present research results for improving HTR call registration and control methods using network signaling information and fuzzy control mechanisms. We concluded that it showed fast congestion avoidance mechanisms with a fewer system load maximized the efficiency of network resources by restricting ineffective machine attempts.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.107-117
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• 1998

In this paper, a deadbeat controller design technique is developed for the recently introduced PFC(Power Factor Correction) circuit named as a QBSRR(Quantum Boost Series Resonant Rectifier) to achieve the fast dynamic responses of the output voltage in the presense of any load variations. And, in order to monitor the load information without employing the current sensor, the load estimation method is also derived. By using the information of the load estimation method, the proposed controller gain is automatically adjusted to have the system always keep the very fast dynamic responses. To verify these superior performances, the simulation and the experiment are carried out.