• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.98-102
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• 2017

In this paper, we study RF-powered backscatter cognitive radio networks to improve the performance for the secondary user which is backscatter radio based wireless sensors. In our proposed model, we consider an avoiding the doubly round-trip attenuation to add a carrier emitter and utilization of spectrum sensing information. When the primary channel is busy, the secondary user is able to harvest RF energy from the channel through a hybrid-access point (H-AP) and a carrier emitter. When the channel becomes idle, the secondary user will be use the harvested energy to operate wireless sensors, to use the sensing and to backscatter through the carrier emitter. We model mathematically the deterministic and multisource elements of a number of tagged channels. In the proposed communication environment, we show the BER performance of the backscatter communication using WiFi signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.8-16
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• 2012

In order for the support of the ETCS (Electronic Toll Collection System) model, which have been operated successfully till now, with multi-lane service, the wireless communication system of the multi-lane-supported ETCS based on RF-DSRC (Radio Frequency - Dedicated Short Range Communication) was used. In this paper, the SME algorithm attaching data flow and form into RFID communication technology was newly suggested to overcome technical problems on RF-DSRC communication system. In addition, in order to verify the SME algorithm, experiments based on ETCS and 900Mhz RFID were carried out. From the result of realization experiment of RFID dependent on the velocity and precision experiment of information inside of RFID, we can see that RFID is detected below 70Km/h and the precision of estimation is more than 90%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1289-1295
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• 2007

In this paper, we implemented high-performance concurrent control system which manages whole RF systems with digital type and communicates with remote station on both wire and wireless networking. It consists of FPGA (Field Programmable Gate Array) part which controls forward/reverse LPA (Linear Power Amplifier), forward/reverse LNA (Low Noise Amplifier), channel cut wire/wireless TCP/IP, etc, master microprocessor (AVR), which manages the whole control system, Slave microprocessor which communicates SA (Spectrum Analyzer) and observes frequency spectrum of each channel with the resolution of 5KHz, 10 channel card microprocessor which independently observes each channel card and sets frequency synthesizer in channel cut and other peripherals and logics. The whole system is divided to two parts of H/W (hardware) and S/W (software) considering operational efficiency and concurrency, and implementation and cost. H/W consists of FPGA and microprocessor. We expected the optimized operation through H/W and SW co-design and hybrid H/W architecture.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.109-114
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• 2011

Ka-band payload of COMS (Communication, Ocean and Meteorological Satellite) launched in June 2010 was developed by ETRI with Korean local companies and also the in-orbit test (IOT) for the Ka-band payload was carried out entirely with domestic technology. The Ka-band payload IOT consisted of the antenna pattern measurements and the payload RF performance test was performed during about 40 days from 10 days after the launch. In this paper, the IOT methods and the results for the Ka-band payload are described in detail. According to the comparisons of each IOT test result with the corresponding ground test result, we can show that the Ka-band payload IOT and verification was successfully achieved and that all Ka-band channels of COMS are to be normal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.231-238
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• 2015

In this paper, we have studied a sheet resistance property of N- and P-type thin films deposited on ITO glass by use of RF magnetron sputtering. The N-type samples which has the deposition condition of 150W RF power, shows the highest current value, and the samples deposited for 15 minutes shows a better Ohmic contact property. As the substrate temperature, RF power and deposition time are increased, the sheet resistance of the samples is increased, and the low sheet resistance sample shows a better I-V property. The P-type samples shows the highest current value by 150W RF power condition as similar as N-type samples. and the samples deposited for 20 minutes shows a better ohmic contact property. The sheet resistance of the both types samples is increased as increasing RF power and deposition time.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.88-91
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• 2015

Wireless power transmission (WPT) is a technology using free space as a conductor for transmitting electric power, which aims to transfer not just the transmission signal but also the electrical energy itself. This paper takes issue with the microwave wireless transmission technology utilizing in long-distance transmission. To construct the WPT system, several components are needed, such as RF Oscillator which converts AC power to RF through DC status, high gain antenna and RF rectifier that converts RF back to DC. The array topology is good a candidate for wide use. The objective of this research is to study the efect of the WPT systmem on electric power system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.49-53
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• 2018

Parabolic offset antenna is widely used for wireless communication system. The general structure of parabolic offset antenna system is composed of supporting stand and RF devices under parabolic reflector. However sidelobe distortion in gain pattern is occurred by supporting stand and RF devices. Depending on position of subsidiary devices, angle of sidelobe distortion can be changed. In this paper we describe method for sidelobe distortion suppression using raytracing. We calculate 3D vector for sidelobe distortion suppression zone by raytracing method and compare when subsidiary device is in sidelobe distortion suppression zone or not. By comparison, we show method for parabolic antenna sidelobe distortion suppression.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2669-2671
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• 2003

본 논문에서는 변위 손상 현상을 이용하는 중성자 탐지소자와 선량계 모듈에 RF 통신 기능을 추가하여 방사선 환경 내에서 내 방사선화 된 로봇에 의해 가동 중인 원자력 밭전소등의 특정 부분에 대하여 실시간에 측정된 방사선량 데이터의 취득이 가능한 모듈을 개발하였다. 기존의 운용중인 발전소에 대한 방사선량은 휴지기간에 탐지소자를 설치하여 다음 휴지기간에 그 탐지소자를 가지고 나와 누적방사선량을 측정하거나, 설치된 탐지소자에서 유선으로 안전한 곳까지 데이터를 취득해 와서 그 값을 분석하여 왔으나, RF 통신 기능이 추가된 모듈은 내 방사선화 된 로봇에 탑재하여 로봇이 가동 중인 발전소 곳곳을 누비며, 설치된 탐지소자로부터 그 방사선량을 취득한 수 있다. 이는 기존의 취득방식에 비해 많은 부분 효율적인 측면이 있으며, 유지보수 비용의 절감을 가져 올 수 있을 것으로 기대된다. 본 연구에서는 RF 통신을 하기 위한 안테나 회로의 설계 기법과 취득한 정보를 EEPROM에 저장하고, 그 저장 데이터를 로봇에 부착된 Reader에 의해 읽을 수 있는 일련의 흐름을 구성하는데 있어 필요한 여러 가지 기술 혹은 기법에 대하여 살펴보았다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.377-377
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.333-333
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• 2004