• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.902-905
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• 2006

This paper presents a new RF testing scheme based on a design-for-testability (DFT) method for measuring functional specifications of RF integrated circuits (IC). The proposed method provides input impedance. gain, noise figure. input voltage standing wave ratio (VSWR) and output signal-to-noise ratio (SNR) of a low noise amplifier (LNA). The RF test scheme is based on theoretical expressions that produce the actual RF device specifications by output DC voltages from the DR chip.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.72-77
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• 2004

The purpose of this study is to develop temperature measurement system with Rf sensors on shoes dry process. The experimental results showed that the developed system successfully could be applied on real dry process to reduce defective shoes caused from insufficient dry with scientific data management.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1567-1570
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• 2022

This paper, we presents a RF protection technique of antenna switch by improving the power handling capability in worst case environment mode for mobile phone applications without critical payment of circuit performances such as insertion loss, isolation and ACBV (AC breakdown voltage). By applying a additional capacitive path located in front of the antenna in cell-phone, it performs the effective reduction of input power in high voltage standing wave ratio (VSWR) condition. Under the all-path off condition which causes a high VSWR, it achieved 37.7dBm power handling level as high as 5.7dB compared to that of conventional one at 2GHz. In addition, insertion loss and isolation performances were 0.31dB and 42.72dB at 2 GHz, respectively which were almost similar to that of the conventional circuit. The proposed antenna switch was fabricated in 130nm CMOS SOI technology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.638-646
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• 2005

In recent wireless communications, direct conversion transceiver or If sampling SDR-based receivers have being designed as an alternative to conventional transceiver topologies. In direct conversion receiver a.chitectu.e, the 1.equency/phase offset between the RF input signal and the local oscillator signal is a major impairment factor even though the conventional AFC/APC compensates the service deterioration due to the offset. To rover the limited tracking range of the conventional method and effectively aid compensation scheme in terms of I/Q channel imbalances, the frequency/phase offset compensation in RF-front end signal stage is proposed in this paper. In RF-front end, the varying phase offset besides the fixed large frequency/phase offset are corrected by using early-late phase compensator. A more simple frequency and phase tacking function in digital signal processing stage of direct conversion receiver is effectively available by an ingenious frequency/phase offset tracking method in RF front-end stage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.970-976
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• 2010

Platform convergence originated from the convergence of broadcast and telecommunication is making rapid progress including IT and not-IT fields in order to provide a variety of converged services, S/W eco-system construction, and so on. With the advent of convergence environment, IEEE 802.15.4-based RF4CE technology is rising because of creating momentum for the market using converged connectivity between home and office devices as well as all around located devices. In this paper, we present enhanced RF4CE key seed distribution approach in order to provide efficient connection and control between devices. The proposed approach consists of device mutual authentication, initial vector assignment, and two-phase key seed distribution. Moreover, we make a development real RF4CE test board and its key agreement simulator to verify the proposed approach.

• 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.