• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.519-522
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• 2010

본 논문에서는 RF 송수신기를 이용하여 데이터를 전송하고, 전송받은 데이터를 이용하는 가운데 안전하게 통신하기 위한 방법으로 RFID 통신 프로토콜을 이용한 암호화 방법을 연구한다. 그리고 이러한 통신 프로토콜을 이용하여 안전하고 편리한 PC 보안 방법을 연구한다. 이러한 PC 보안 방법은 PC 가까이에 Tag를 소지한 사용자가 있는지 유무 판단을 하여 자동으로 PC를 보호한다. 또한 위조 변조가 불가능하며, 스니핑 공격과 스푸핑 공격에 대해 안전하다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.8
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• pp.1813-1819
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• 2011

In this research, the location positioning system supposed is concerned with range recognition technology using phase and magnitude of radio wave and adding technology of image histogram by vision. By the proposed technology, we design the radio transmitter and receiver and realize the measurement system, and save the data in disk that is earned from 900Mhz RF signal, middle frequency 450Khz of analog signal. Range information is earned the data through digital signal processing of IF signal. For the estimation of range measured, we analyze the difference between real range and measurement range, and also suggest the method to improve the measurement error using average processing and amplitude properties.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.7
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• pp.24-30
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• 2000

In this paper, we proposed an fiber-optic transceivers based on the analog optical transmission techniques of incorporating the SCM (subcarrier multiplexing) and WDM (wavelength-division multiplexing ) method, which can be used to transmission of IMT-2000 and PCS wireless frequency band and analyzed overall those parameters related with fabrication. Especially in the impedance matching network between RF signal and LD, we proposed the method of deriving optimal performance using simulation techniques. In the frequency band of 1.7GHz∼2.25GHz, experimental data for the gain flatness and the noise floor of the optical link were also presented $\pm$1.5dB and -130dBm respectively when the link Rain was 0dB.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.413-418
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• 2009

The S-band Transponder for telemetry and command of small satellite is designed and fabricated as prototype model using COTS(Commercial Off-The-Shelf) components. QPSK modulator and demodulator of transponder is implemented by using FPGA for system extension. The transponder consists of RF Front End, RF Modulator, RF Demodulator, and MODEM. The measured results of fabricated transponder show BER of less than $1.1{\times}10^{-6}$ at -105 dBm input power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.889-891
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• 2017

Visible light communication technology, which is a communication using LED lighting, is defined by IEEE 802.15.7 WG and active research is under way. Visible light communication is advantageous not only to avoid interference with existing RF communication but also to provide location based service through accurate positioning by utilizing LOS (Line of Sight) characteristic. Therefore, it is very easy and efficient to locate and track the user's location. In this paper, we implemented a visible light communication transceiver using USB interface for easy application to portable devices. It supports the mobility of mobile devices through internet protocol and showed BER performance of less than $10^{-3}dBm$ at over 1m, which is the height of lighting and smart device during walking.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.70-75
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• 2014

This paper presents a IR-UWB(Impulse Radio Ultra-Wide Band) transceiver circuit for data communication and real time location system. The UWB receiver is designed to OOK(On-Off Keying) modulation for energy detection. The UWB pulse generator is designed by digital logic. And the Gaussian filter is adopted to reject side lobe in transmitter. The measured sensitivity of the receiver is -65 dBm at 4 GHz with 1 Mbps PRF(Pulse Repetition Frequency). And the measured energy efficiency per pulse is 20.6 pJ/bit. The current consumption of the receiver and transmitter including DA is 27.5 mA and 25.5 mA, respectively, at 1.8 V supply.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.53-57
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• 2001

본 논문에서는 WCDMA 규격[1,2]에 근거하여 WCDMA 기지국 무선부 설계 파라미터들로서, 수신기 잡음 지수(NF:Noise Figure), IIP3(Input 3$^{rd}$ order Intercept Point), ACS(Adjacent Channel Selectivity) 와 Blocking 특성을 만족하기 위한 여파기의 감쇠 특성 및 송신기 전체의 ACLR 특성을 만족하기 위한 송신기 구성 소자의 ACLR 특성 등을 고찰하였으며, 이와 같은 무선부 설계 파라미터를 기본으로 구현한 무선부의 시험 결과를 기술하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1165-1171
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• 2006

In this paper, we designed radio data transceiver to control the machine or equipments for automation in local areas. The designed module can transmit data with 153.6Kbps and uses 424MHz RF carrier to transmit data in the ISM band regulation. It has a processor, CPLD chip of the Altera Company, to control the data in transmitting and receiving. The processor is implemented by programming with VHDL. We will make this module with compact in dimension and higher data rate and apply to RFID technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.139-146
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• 2009

This paper presents an average internal loop-back antenna calibration method for array antenna in TDD(Time Division Duplex) systems. The proposed method calibrates the amplitude and the phase of RF systems using into mal coupler and switches without aids of external calibration systems. The average calibration scheme of the proposed method also increases reliability of calibration performance. Computer simulation demonstrates that the proposed method corrects beamforming angles of DOA estimation algorithm and BER performance in transmit power allocation scheme.

• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.337-343
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• 2016

In this paper, we newly introduce a wireless identification system using a solar cell and RF transceivers. The reader sends interrogating signal to a transponder using LED visible light, and the transponder responds to the reader using RF signal. The transponder consists of a solar cell, an amplifier, a microprocessor, and an RF transmitter. The solar cell receives the visible light from the reader and generates current to supply electric power to the other devices in the transponder. At the same time, the solar cell detects interrogating signal in the reader light. The microprocessor senses the interrogating signal and generates a responding signal. The RF transmitter radiates the responding signal to the reader. The transponder is a passive circuit because it operates without external power. In experiments, the maximum read distance between a reader and a transponder was about 1.6 meter.