• Proceedings of the IEEK Conference
• /
• 2001.06e
• /
• pp.103-106
• /
• 2001

In this paper, a soft switching half-bridge converter using secondary switches for output control and conduction loss reduction is proposed. The conventional half-bridge converter must be fixed on duty cycle for soft switching. The proposed converter was consisted of two added switches in series of the secondary rectifier diodes. The main switches with constant duty cycle are operated ZVS. The secondary switches are operated ZV-ZCS. Especially, the primary switches were fixed duty cycle for maximum voltage conversion ratio. Output of converter is controlled by duty cycle or phase-shifted time of secondary switches. The conduction loss of the proposed converter can be reduced by the secondary switches. The operation characteristic, analysis, simulation and experimental results of the proposed converter are presented.

• Proceedings of the KIEE Conference
• /
• 2001.10a
• /
• pp.205-207
• /
• 2001

In response to this inverter microwave oven has been developed to improve high speed cooking time & energy saving performance. The voltage resonating inverter has a defect in switching element that works at 5 or 6times higher than input voltage. Especially, it is very difficult to choose the switching device is very high for the 220 (V) commercial voltage. In this paper, it is proposed the optimum method to realize the turbo 1200(W) output power for microwave oven that is employed the 900(V) IGBT with decreasing operating voltage of the switching component by making the 220(V), 1000(W) inverter through the active clamp voltage resonating inverter.

• Journal of the Korean Data and Information Science Society
• /
• v.23 no.4
• /
• pp.859-866
• /
• 2012

Some switching properties of multivariate control charts are investigated when the interval between two consecutive sample selections is not fixed but changes according to the result of the previous sample observation. Many articles showed that the performances of variable sampling interval control charts are more efficient than those of fixed sampling interval control charts in terms of average run length (ARL) and average time to signal (ATS). Unfortunately, the ARL and the ATS do not provide any information on how frequent a switch is being made. We evaluate several switching properties of two sampling interval Shewhart and CUSUM procedures for controlling mean vector of correlated quality variables.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.58-62
• /
• 2004

The PWM inverter drive my cause motor terminals voltage surge and oscillation(ringing), which impose severe electric stresses on inter-turn insulation of motor windings. This paper describes the technique used to simulate the problems associated with the use of PWM ASD's(Adjustable Speed Drive) to drive induction motor. The characteristic of switching surge was analyzed by EMTP(Electromagnetic transient program) model. The effects of switching surge by surge impedance, rise-time and cable lengths are also discussed.

• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.188-189
• /
• 2017

There has been a growing demand for power semiconductor switches equipped with high-voltage blocking capability of kV range and fast-switching characteristics of ns range in various plasma application. This paper investigates the application of SiC MOSFETs in the particular plasma application which requires the blocking voltage of 4.5kV and the switching transient time of less than 100ns. In order to meet the required blocking voltage, the series connection of multiple SiC MOSFETs is adopted in this paper. Also, snubber capacitors are employed to equalize the voltage sharing among the series connected SiC MOSFETs. The simulation and experimental result successfully verifies the application of SiC MOSFETs and snubber capacitors in the plasma application requiring high-voltage and fast-switching load dynamics.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.163-166
• /
• 2001

In this paper, a two-level switching algorithm ov the deadbeat to control PWM inverter is proposed. A modified algorithm of the deadbeat is suitable for the UPS system. Two levels in the pulse pattern are used. This scheme allows the use of higher switching frequency for a given computation time delay, which results in lower total harmonic distortion at the output. The proposed control scheme is implemented using TMS320F240 DSP for controlling on inverter.

• Proceedings of the KIEE Conference
• /
• 2001.10a
• /
• pp.57-60
• /
• 2001

This paper presents a new method for removing reaching phase in variable structure control systems using Bell type switching function. By proposed method, during the entire control process reaching phase is removed. For effective speed control of trapezoidal type brushless DC motor, a time varying switching function based speed controller is developed as illustration.

• ETRI Journal
• /
• v.44 no.2
• /
• pp.274-285
• /
• 2022

Retransmission in optical burst switching networks is a solution to recover data loss by retransmitting the dropped burst. The ingress node temporarily stores a copy of the complete burst and sends it each time it receives a retransmission request from the core node. Some retransmission schemes have been suggested, but uncontrolled retransmission often increases the network load, consumes more bandwidth, and consequently, increases the probability of contention. Controlled retransmission is therefore essential. This paper proposes a new controlled retransmission scheme for loss recovery, where the available bandwidth of wavelength channels and the burst lifetime are referred to as network conditions to determine whether to transmit a dropped burst. A retrial queue-based analysis model is also constructed to validate the proposed retransmission scheme. The simulation and analysis results show that the controlled retransmission scheme is more efficient than the previously suggested schemes regarding byte loss probability, successful retransmission rate, and network throughput.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.28 no.1
• /
• pp.48-58
• /
• 2023

This paper presents the digital control techniques of a bidirectional CRM(critical-conduction mode) buck(boost) converter, a dead-time design method that optimizes ZVS(zero-voltage switching) and valley-switching operation, and a switching-frequency limitation that ensures stable converter operation. To verify the feasibility of the design, a Si-MOSFET-based bidirectional CRM buck(boost) converter is built with 260-430 V input, 160-240 V output, and 1.0 kW rated capacity. The bidirectional CRM converter achieves an efficiency of up to 99.6% at buck mode and 98.7% at boost mode under rated load conditions.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.729-738
• /
• 1995

We consider a priority-based packet-switching system with three phases of the packet transmission time. Each packet belongs to one of several priority classes, and the packets of each class arrive at a switch in a Poison process. The switch transmits queued packets on a priority basis with three phases of preemption mechanism. Namely, the transmission time of each packet consists of a preemptive-repeat part for the header, a preemptive-resume part for the information field, and a nonpreemptive part for the trailer. By an exact analysis of the associated queueing model, we obtain the Laplace-Stieltjes transform of the distribution function for the delay, i.e., the time from arrival to transmission completion, of a packet for each class. We derive a set of equations that calculates the mean response time for each class recursively. Based on this result, we plot the numerical values of the mean response times for several parameter settings. The probability generating function and the mean for the number of packets of each class present in the system at an arbitrary time are also given.