• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.71-72
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• 2013

최근 철도시스템 분야에서도 기존의 접촉식 가공 전차선 급전 방식을 벗어나 새로운 개념의 에너지 전송시스템으로써 무선급전시스템의 다양한 응용 연구가 진행되고 있다. 본 논문에서는 전자기 유도방식의 일종인 무선급전시스템을 철도차량에 적용시키기 위해 운전조건에 따른 특성 연구를 수행 하였다. 전력 전송의 효율을 높이기 위해 유도급집전체(IPT, Inductive Power Transformer)의 누설 자속(Leakage Flux)을 보상할 수 있는 6-kW 60-kHz 시제품(Laboratory Prototype)을 제작하여 급전체와 집전체간 위치 변화에 따른 무선급전시스템의 전력전송량 변화를 알아보았다. 또한. 급전체와 집전체간 위치 변화에 따라 변하는 누설 자속을 측정하고 운전주파수를 변경하여 무선급전시스템의 전력전송량의 변화를 알아보았다.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.49-54
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• 2017

In this paper, we propose magnetic field wireless power transfer antenna using Ferrite. It is possible to transfer magnetic field wireless power without independent ground by using characteristic of ferrite in the point that conventional magnetic field wireless power transfer was possible with independent grounding. Ferrite has a shielding effect of magnetic field and reduces leakage power, thereby improving transfer efficiency. We propose an antenna for magnetic field wireless power transfer using ferrite and confirmed that it is transmitted by 5W magnetic field wireless power through experiments. The wireless power transfer proposed in this paper can be applied variously to the Internet of things by using the magnetic field wireless power transfer through the metal.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.186-187
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• 2010

현재 국내 기준 약 40만대의 승강기가 운행중이며, 승강기 전력의 약 40%가 회생되고 있다. 본 논문에서는 승강기의 회생전력을 계통연계형 태양광 연계형 인버터에 추가 함으로써 일사량에의존한 태양광 발전의 효율을 개선하고자한다. 제안된 시스템의 동작모드는 크게 연계형 태양광 인버터 발전 및 승강기 회생 전력 부분으로 나누어지며 인터페이스 장치에의하여 승강기 회생 전력을 태양광 발전용 전력 변환 장치로 전송한다. 본 연구에서는 제안한 시스템의 유용성을 확인하기위하여 시뮬레이션 및 실험을 수행하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.23-28
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• 2008

In this paper, we propose location-aided cooperative routing protocol (LACARP) for supporting power saving and stable route lifetime in mobile ad-hoc wireless sensor networks. The main ideas and features of the proposed routing protocol are as follows. First, the definition of the area of route search using location-based information to support power saving transmission. Second, the expect zone-based establishment of routing route within the area of route search. Third, the cooperative-aided transmission method. In the operation of data transmission over the established rout the datas are transmitted via both the established route and cooperative route aided by neighbor nodes. The performance evaluation using OPNET(Optimized Network Engineering Tool) shows the LACARP can improve the packet delivery ratio and power saving transmission efficiently.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.52-56
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• 2014

In this paper, a high-efficiency power amplifier is implemented using a gate and drain bias control circuit for WPT (Wireless Power Transmission). This control circuit has been employed to improve the PAE (Power Added Efficiency). The gate and drain bias control circuits consists of a directional coupler, power detector, and operation amplifier. A high gain two-stage amplifier using a drive amplifier is used for the low input stage of the power amplifier. The proposed power amplifier that uses a gate and drain bias control circuit can have high efficiency at a low and high power level. The PAE has been improved up to 80.5%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.559-568
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• 2002

In this paper, we studied on combining the control of transmission fates and power for the real system where a finite set of transmission rates are used. In [1], the combined control of transmission rates and power was first researched, and suggested the Selective Power Control (SPC) algorithm. However, it can't guarantee the minimum rate to each user and results in frequent changes of rate due to oscillation of the SIR (Signal to Interference Ratio) values. As a main purpose of this paper, we derive a formulation model and propose a distributed iteration algorithm to solve these problems. To evaluate the performance of the proposed algorithm, we carried out numerical analysis and computational experiments. The results indicate that the proposed algorithm achieves better throughput than conventional one by keeping the low average transmission power.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.203-204
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• 2016

무선전력전송은 특성상 수신부에 수신되는 전압이 일정하지 않기 때문에 수신부에 넓은 입력 범위를 갖는 정전압 컨버터가 요구된다. 그 중 Buck-Boost 컨버터는 넓은 입력 범위를 갖기 때문에 무선전력전송 수신부의 정전압 컨버터로 많이 사용 되었다, 본 논문에서는 기존의 Buck-Boost 컨버터의 효율 향상을 위해 Synchronous Buck-Boost 컨버터를 제안하고 시뮬레이션을 통해 두 컨버터를 비교하여 개선된 결과를 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.247-260
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• 2007

This paper solves the problem of finding a suitable sub-channel and power joint allocation method for multiple users in 802.16e OFDMA/TDD cellular systems. The joint allocation is thatfirstly the sub-channel is allocated to the users and then suitable power is allocated. We propose a FASA (Fairness insured Aggressive Sub-channel Allocation) algorithm which is a dynamic channel allocation algorithm considering all users' channel state information conditionally to maximize fairness and throughput. The improved CHC algorithm, which is dynamic power allocation algorithm, is also proposed in this paper The Improved CHC algorithm collects the extra of the downlink transmit power and then re-allocates it to other users. Simulation results show that the proposed improved CHC algorithm additionally increases the fairness and sector throughput.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.78-83
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• 2010

In this paper, a novel dual-band power amplifier using metamaterials has been realized with one RF GaN HEMT diffusion metal-oxide-semiconductor field effect transistor. The CRLH TL can lead to metamaterial transmission line with the dual-band tuning capability. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. We have managed only the second- and third-harmonics to obtain the high efficiency with the CRLH TL in dual-band. Also, the proposed power amplifier has been realized by using the harmonic control circuit for not only the output matching network, but also the input matching network for better efficiency. Two operating frequencies are chosen at 900 MHz and 2140 MHz in this work. The measured results show that the output power of 39.83 dBm and 35.17 dBm was obtained at 900 MHz and 2140 MHz, respectively. At this point, we have obtained the power-added efficiency (PAE) and IMD of 60.2 %, -23.17dBc and 67.3 %, -25.67dBc at two operation frequencies, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.285-289
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• 2018

In this paper, we demonstrate electromagnetic wave focusing and rectification based on time reversal as a smart method for far-field wireless power transfer. Time reversal in a complex propagation environment allows for transmission of high peak power pulses by focusing the electromagnetic waves selectively regardless of the receiver position. We demonstrate wave focusing and radio frequency (RF) to direct current (DC) rectification via numerical simulation of a complex propagation environment. The results reveal that time reversal can ensure peak power up to 12 dB greater compared to a narrowband continuous wave signal, thereby enhancing the rectified DC voltage with better efficiency.