• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.687-692
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• 2013

This paper presents a compact power divider using microstrip-slotline transition technology. By using the microstrip-slotline transition, the ${\lambda}/4$ transmission lines of the divider can be changed to two ${\lambda}/8$ transmission lines in the multilayer structure. In the microstrip-slotline transition, we have used via holes to make a short circuit at the microstrip line and embedded spiral configuration stubs to reduce the electrical length of an open circuit at the slotline end point. For validating the microstrip-slotline technique, we have simulated and implemented the power divider with embedded spiral and via hole configuration circuits at a frequency of 2 GHz. Good agreement between the simulation and the measurement results is obtained at the operating frequency.

• Journal of Power Electronics
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• v.7 no.1
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• pp.55-63
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• 2007

This paper proposes a simple unity power factor zero-voltage-transition (ZVT) pulse-width-modulated (PWM) single-phase rectifier, which features reduced switching and conduction losses. The switching loss reduction is achieved by a simple auxiliary commutation circuit, and the conduction loss reduction is achieved by employing a single-stage converter, rather than a typical double-stage converter comprising of a front-end rectifier and a boost rectifier. Furthermore, thanks to good features such as a simple PWM control at constant frequency, low switch stress, low Var rating of commutation circuits, and simple power circuit structure, it is suitable for high power applications. The principles of operation are explained in detail, and a major characteristics analysis and the experimental results of the new converter are also included in this paper.

• The Transactions of the Korea Information Processing Society
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• v.6 no.3
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• pp.766-772
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• 1999

With the increase of portable system and high-density IC, power consumption of VLSI circuits is very important factor in design process. Power estimation is required in order to estimate the power consumption. A simple and correct solution of power estimation is to use circuit simulation. But it is very time consuming and inefficient way. Probabilistic method has been proposed to overcome this problem. Transition density using probability was an efficient method to estimate power consumption using BDD and Boolean difference. But it is difficult to build the BDD and compute complex Boolean difference. In this paper, we proposed Propowest. Propowest is building a digraph of circuit, and easy and fast in computing transition density by using modified COP algorithm. Propowest provides an efficient way for power estimation.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.698-704
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• 2005

Power consumption for paddle impeller in spherical and cylindrical agitated vessel was measured over a wide range of Reynolds number from laminar to turbulent flow regions. The power correlation was obtained for both spherical and cylindrical vessels, where the apparent diameter of the spherical vessel was equal to the diameter of the cylindrical vessel (height equal to its diameter and had the same volume as the spherical vessel). The power consumption well correlated with the experimental results of Nagata, et al. and Hixson-Baum. Also the critical Reynolds numbers was directly related to the transition coefficient $C_{tr}$ characterizing the transition from a laminar to a turbulent flow region in the correlation proposed here.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.297-303
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• 2005

We present the double resonance optical pumping(DROP) spectra according to the laser power, the polarization combination of lasers, and the alignment of lasers in the transition $5P_{3/2}-4D_{5/2}\;and\;5P_{3/2}-4D_{5/2}$ of $^{87}Rb.$ We observed obviously changing DROP spectrum according to the laser power in the transition $5P_{3/2}-4D_{5/2}$ involved the cycling transition. The laser power effects are attributed to the low optical-pumping-effect in the cycling transition. We observed changing DROP spectrum depending on the polarizations of the lasers. The laser polarization effects are attributed to the changing transition probability according to the polarizations of lasers. We compared the co-propagation with the counter-propagation and the spectral linewidths were 12.2 MHz and 6.9 MHz, respectively.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.619-620
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• 2008

Reactor starting method has the advantage of simplicity and closed transition in spite of lower starting torque per kVA. This method allows a smooth start with almost no observable disturbance on transition and is suitable for applications such as centrifugal pumps or fans. Starting power factor is specially low. Power factor application is needed to compensate for the lower power factor of induction motor. This power factor compensation systems is being hit by the effects of the starting reactor connection position. This paper describes voltage and current stress affected by the installation position of power factor compensation application at the reactor starting method.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.55-66
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• 2019

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5B
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• pp.317-326
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• 2012

Recently, many researchers have studied to solve the energy consumption of network equipments since the interest of Green IT has been increased. In this paper, we apply Low Power Idle (LPI) to OBS network to reduce energy consumption of network devices. Many previous researches have focused on maximizing the sleep time of network equipments to increase the energy saving efficiency of LPI. But transition overhead caused by LPI might not only depreciate the performance of energy saving but also increase packet delay. In this paper, Transition Decision (TD) algorithm is proposed to improve energy saving efficiency by reducing the number of unnecessary transition and guarantee the required QoS such as packet delay. To evaluate the performance of proposed algorithm, we model OBS edge router with LPI by OPNET and analyze the performance of the proposed algorithm in views of energy saving, transition count and average packet delay.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.21-26
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• 2016

In this paper we proposed a new structure of spatial combining power amplifier working in 60GHz global unlicensed band(56-64GHz) for the backhaul in the 5 generation mobile systems. The proposed structure is suitable to realize an antipodal finline transition in millimeter wave band, in which the size of cross section of waveguide becomes about a few mm ${\times}$ a few mm, due to its compact structure of the transition and shows effective heat sinking characteristics because its ground plane can contact to the body metal. However, the HFSS simulation results showed the return loss improvement by 1.27dB and the same insertion loss of -1.65dB compared with the conventional structure, which said nevertheless the advantages, there was no deterioration in the performance.

• Journal of Power Electronics
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• v.17 no.1
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• pp.41-55
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• 2017

This study proposes a novel zero voltage transition (ZVT) pulse width modulation (PWM) DC-DC interleaved boost converter with an active snubber cell. All the semiconductor devices in the converter turn on and off with soft switching to reduce the switching power losses and improve the overall efficiency. Through the interleaved approach, the current stresses of the main devices and the ripple of the output voltage and input current are reduced. The main switches turn on with ZVT and turn off with zero voltage switching (ZVS). The auxiliary switch turns on with zero current switching (ZCS) and turns off with ZVS. In addition, the snubber cell does not create additional current or voltage stress on the main switches and main diodes. The proposed converter can smoothly achieve soft switching characteristics even under light load conditions. The theoretical analysis and operating stages of the proposed converter are made for the D > 50% and D < 50% modes. Finally, a prototype of the proposed converter is implemented, and the experimental results are given in detail for 500 W and 50 kHz. The overall efficiency of the proposed converter reached 95.5% at nominal output power.