• 한국정보처리학회논문지
• /
• 제7권8호
• /
• pp.2484-2496
• /
• 2000

네트워크 연결을 위한 고속 스위치는 계속해서 발달하여 왔으며, 스위치가 필요한 성능을 내는가를 여러 조건으로 분석하는 것은 중요한 일이다. 하지만, 복잡한 구조를 가진 시스템을 모델링하여 그 성능을 측정하는 것은 쉬운 일이 아니다. 큐잉이론을 이용한 모델링은 큰 상태 공간을 고려해야 됨은 물론이고 성능평가에 있어서도 복잡한 계산과정을 수행해야 하지만, SAN(Stochastic Activity Networks)에 의한 모델링과 성능평가는 그에 비해 간단하다는 장점이 있다. 본 논문의 목적은 출력포트에 큐를 갖는 고속 ATM 스위치를 확장된 SPN(Stochastic Petri Net)인 SAN을 이용해 모델링하고, 셀 도착 과정은 실제 트래픽과 유사한 특징을 가지고 있는 MMPP(Markov Modulated Poisson Process)로 모델링하여 그 성능을 평가하는데 있다. MMPP 모델을 이용한 버스티 트래픽을 고겨한 성능측정과 아울러 SAN의 장점을 이용한 확장이 용이한 스위치 모델을 보이고자 한다. 제한된 버퍼 크기를 갖는 출력 큐잉 ATM 스위치에 도착하은 셀은 포아송 도착 과정에서는 정확히 표현할 수 없는 버스티 특징을 표현할 수 있어 좀더 실제 트래픽에 가까운 MMPP로 모델링한다. SAN 모델은 UltraSAN 소프트웨어 패키지를 이용해 대기행렬의크기, 지연시간 그리고 셀 손실률에 대한 성능을 측정한다.

• Journal of the Optical Society of Korea
• /
• 제7권4호
• /
• pp.253-257
• /
• 2003

We propose and demonstrate a novel polarization- and wavelength-independent digital electrooptic switch in $Ti:LiNbO_3$ with switching voltage of ${\pm}$32V at $1.55{\mu}m$ wavelength. This $2{\times}2$ integrated optic switch is characterized by a step-like response to the applied voltage. Switching is achieved through adiabatic mode evolution in an asymmetric waveguide junction. An average insertion loss of ∼4.5dB and polarization independent switching with average crosstalk of -12dB are achieved.

• 전자공학회논문지B
• /
• 제33B권11호
• /
• pp.167-174
• /
• 1996

For the decreasing of switching loss, this paper designs the improved buck converter circuit and then compare with the conventional buck converter and finally analyzes the performance. When the switch is turn-off, in the buck converter using the smoothing capacitor, the flow of transient current and peak voltage having the high frequency components was generated because of the instantaneous open-state in the teminals of the switch. However, the buck converter presented in this paper eliminated this disadvantage by using the L-C circuit. Therefore, the higher PF in 0.85 is achieved than that of the buck converter using the smoothing capacitor. Also, due to the decreasing of the harmonic contain rate, the current usage rate is to be higher than that of the conventional buck converter by 4.48dB and the output voltage varient rate for the step response is to be lower 1.32 times than that of the conventional buck converter.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제1권4호
• /
• pp.448-456
• /
• 2012

This paper presents a multilevel inverter configuration which is designed by insertion of a bidirectional switch between capacitive voltage sources and a conventional H-bridge module. The modified inverter can produce a better sinusoidal waveform by increasing the number of output voltage levels. By serial connection of two modified H-bridge modules, it is possible to produce 9 output voltage levels including zero. There are 24 basic switching patterns with the 9 output voltage levels. Among the patterns, we select the 2 most efficient switching patterns to get a lower switching loss and minimum dv/dt stress. We then analyze characteristics of Total Harmonic Distortion (THD) of the output voltage with variation of input voltage by computer-aided simulations and experiments.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.799-802
• /
• 1998

As we know, gigabit ethernet is a new technology to be substituted for current fast ethernet used widely in local area network. The switch used in gigabit ethernet should deal with frames in giga-bps. To do such a fast switching, we need that serveral processes meet the budgets, such as MAC address table lookup, several giga speed path setup, fast scheduling, and etc. Especially MAC address table lookup has to be processed in the same speed with speed of incoming packets, thus the bottleneck in the process can cause packet loss by the overflow in the input buffer. We devise new practical hardware hashing method to perform fast table lookup by minimizing the number of external memory access and accelerating with hardware.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.385-387
• /
• 1996

A novel two stage soft-switching ac-to-dc convener with power factor correction is proposed. The proposed convener provides zero-voltage-switching (ZVS) condition to main switch of boost pre-regulator without auxiliary switch. Comparing to the conventional two stage approach(ZVS-PWM boost rectifier followed by off-line ZVS dc-dc step down converter), the proposed approach is simple and reducing EMI noise problem. A new simple DC-linked energy feedback circuit provides zero-voltage-switching condition to boost pre-regulator without imposing additional voltage and current stresses and loss of PWM capability. Operational principle, analysis, control of the proposed converter together with the simulation results of 1KW prototype are presented.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.187-193
• /
• 2007

This paper presents the Efficiency Characteristic of Three-Level Converter. Three-Level DC/DC Converter Presented in this paper is used a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switch. This converter reduces the voltage stress across the main switch to half of input voltage. This paper analyses the loss of each component and the various losses for efficiency variation. The result of the analysis are verified using 3kW prototype.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제50권8호
• /
• pp.392-401
• /
• 2001

This paper presents the single-stage high power factor AC to DC converter operated in active-clamp mode. The proposed converter is added active-clamping circuit to boost-flyback single-stage power factor corrected power supply. The active-clamping circuit limits voltage spikes, recycles the energy trapped in the leakage inductance, and provides a mechanism for achieving soft switching of the electronic switches to reduce the switching loss. The auxiliary switch of active-clamping circuit uses the same control and driver circuit as the main switch to reduce the additional cost and size. To verify the performance of the proposed converter, a 100W converter has been designed. The proposed converter gives good power factor correction, low line current harmonic distortions, and tight output voltage regulation, as used unity power factor.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1999년도 전력전자학술대회 논문집
• /
• pp.323-326
• /
• 1999

For decrease the harmonic current components of the power source, a first method is insert the choke coil that used the choke input type rectifier, the booster chopper circuit and buck chopper circuit. And the several method are studying like as the PWM(Pulse Width Modulation) converter and the active filter type which is used the high frequency switching and the sinusoidal wave formed input current. In this type, there are many problem as a low efficiency, increased the noise, the high leakage current and cost up by the high frequency switching. For improve this problems, the partial resonan method is used on the booster inducter and lossles snubber condenser. This method decreased the distortion factor has lower harmonic components than the hard switching and there is no switching loss by the ZCS(Zero Current Switching) at switch turn-on and the ZVS(Zero Voltage Swithcing) at switch turn-off

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1530-1535
• /
• 2003

The automatic load transfer switch (ALTS) typically automatically transfers electrical loads from a normal electrical power source to an emergency electrical power source upon reduction or loss of normal power source voltage. It can also automatically re-transfer the load to the normal power source when the normal voltage has been restored within acceptable limits. The transfer operation of ALTS is accomplished by a spring-driven linkage mechanism. In this paper we build a dynamic model of driving mechanism for ALTS using ADAMS and checked the characteristics of the transfer operation. Finally we performed a detailed design of the driving mechanism through results of analysis and confirmed it to satisfy design requirements.