• Journal of the Korea Computer Industry Society
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• v.2 no.7
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• pp.895-904
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• 2001

In this study, gain can be high because an active double balance mixer was used. Receiving system II was made with receiving system I of low IIP3, a passive double balance mixer which has low gain and high IIP3, and an intermediate frequency amplifier for enhancing the low gain. The result of simulating receiving parameter is as follows： the total NF of receiving system I was 6.4382dB, gain was 53.5dB, and IIP3 was -6.6352dB m. As for the receiving system II, the total NF was 9.70672dB, gain was 47dB, and IIP3 was 3.66729dB m.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1402-1409
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• 2007

In this paper, we propose various types of AGC algorithms for implementing the OFDM communication systems. For the high-speed packet transmission, in this paper, we assume the OFDM system with relatively long and repeated preambles. We propose the maximum sample value counter for counting the number of maximum sample. In the maximum sample value counter, we use the buffer for the digital signal buffering. Finally, the counting value of the maximum sample value counter controls the gain control signal generator by using gain control table automatically.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.105-113
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• 2009

In this paper, a vehicle antenna for AM, FM, TDMB, GPS systems was designed and implemented. AM antenna loaded into small space of shark shape was designed by ferrite turn style antenna. For the FM and TDMB antenna, folded monopole antenna which helical is folded was applied. GPS antenna for achieving characteristics both bandwidth and gain improvement was designed microstrip patch that has air substrate and fractal structure. Receiving signal strengths by the measurement were presented for the AM, FM and TDMB antenna. AM signal strength was -65.7dBm, this strength is almost as same conventional pole antenna as -63.4dBm. It can be replaced conventional pole or glass antenna by the studied antenna. Signal strengths for FM and TDMB were -55.66 and -43.50dBm at center frequency, they are 5~10dB higher than conventional antenna. Measurements of bandwidth and gain for the GPS antenna showed 135 MHz under VSWR 2 : 1 and 4.31dBi, gains over GPS band were 3~5dB higher than ceramic patch antenna.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.74-76
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• 2012

In order to design Transceiver/Receiver antenna with high gain in Ka band, Fresnel zone plate lend(FZPL) antenna is considered and analyzed. Physical optics is applied to demonstrate the FZPL. The FZPL is configured to 11 elements diffraction zones and drived at 20GHz. As a result, calculated received gain using PO method is 33.01dB.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.247-250
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• 2008

본 논문에서는 다중안테나-직교 주파수 분할 다중화(multiple input multiple output orthogonal frequency division multiplexing, MIMO-OFDM)시스템 중 공간 다중화와 전송 다이버시티 이득을 동시에 얻기 위해 제안된 double space-time block code(D-STBC) OFDM 시스템에 대해 기존 수신 기법인 그룹단위 간섭 제거 기법의 문제점을 보완하는 새로운 간섭 제거 기법을 제안한다. 또한 STBC의 다이버시티 이득을 극대화 할 수 있는 컴포넌트 인터리버 구조를 송수신단에 추가함으로써 수신 성능을 크게 향상시킨다. 이동방송 수신을 고려한 빠른 시변 채널환경에서의 전산 모의 실험을 통해 STBC의 부호직교성 상실로 인한 성능열화 현상이 개선됨을 보이고 다비어시티 이득에 의해 수신 성능 향상을 확인한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.35-38
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• 2009

본 논문에서는 신호 공간 다이버시티 (Signal Space Diversity) 기법이 적용된 시스템에서 최대비 합성 (Maximal Ratio Combining) 수신시 성능 이득에 대해서 분석하였다. 먼저 심볼 오류율(Symbol Error Rate)을 수학적으로 유도하였다. 유도된 공식으로부터 상한(Upper Bound) 분석을 통해 공간 신호 다이버시티 기법이 결합될 경우 기존 대비 2배, 즉 '$2{\times}$수신안테나수' 만큼의 다이버시티 이득을 가짐을 증명하였다. 그리고 모의실험 결과와 유도된 공식 결과 값이 서로 일치함을 보여 정확성을 입증하였으며, 유도된 공식을 기반으로 신호 대 잡음비(SNR; Signal-to-Noise Ratio), 수신 안테나 개수 등 주어진 시스템 변수에 따른 최적 회전 각도를 정확히 도출할 수 있음을 보였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.57-62
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• 2008

In this paper, a folded helical monopole antenna for TDMB receiving and a trapezoidal fractal microstrip patch antenna for GPS were designed and fabricated for the vehicle shark antenna. To minimize null which is generating toward antenna axis direction and to receive both vertical polarization and horizontal polarization for TDMB antenna, we fold 90 degree helical monopole element. GPS antenna to get wide bandwidth and gain improvement was designed an air substrate trapezoidal microstrip patch antenna. Fabricated TDMB and GPS antenna were measured for S11 and radiation pattern, and compared with a commercialized antenna. TDMB antenna shows 3 dB higher antenna gain and receiving signal strength than the commercial one. GPS antenna shows the gain of 4.31 dBi at the resonant frequency, which is $3{\sim}5\;dB$ higher gain over whole operating band and 135MHz wide bandwidth at 2:1 VSWR than the conventional ceramic antenna.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.31-38
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• 1990

An antenna gain measurement system using an extrapolation technique is described. The technique is similar to the usual two-antenna method for absolute gain measurement system, but involves the measurement of the received signal as a function of seperation in short distances, and the signal-versus-seperation data is processed in a way that allows an extrapolation of the signal to "infinite" seperation. In this technique it is possible to obtain the near field gain as function of distance by combining the far field gain and a proximity correction factor. The results of gain measurements of standard gain horn antennas and OEG (open ended waveguide) antennas are also presented.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.182-185
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• 1996

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.609-611
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• 1998

본 고에서는 분산 통신망 환경에서 여러 지역에 분산되어 있는 이기종의 각종 시스템들에게 효율적으로 정보보호 서비스를 제공하기 위해 수행중인 프로젝트인 일부분으로서, 송신자가 송신자의 이득을 위해, 수신자가 수신자의 이득을 위해 메시지를 보낸적이 없다고 부인하는 것을 방지하는 발신처 부인방지와 수신처 부인방지 서비스의 제공과 통신망에서 오류에 의한 전송 실패와 수신자의 파일의 수신자부인을 구분해 주는 전송 부인방지 서비스를 제공해주는 FTP를 설계하였다. GSS-APTI를 사용하여 소스 수준에서 호환성을 갖도록 안전성 서비스들에 대해 일관된 인터페이스를 제공하도록 하였고, 응용 클라이언트와 응용 서버간의 안전한 문맥을 확립하기 위해 세션키를 사용하여 효율적인 키 사용으로 공개키 시스템에서의 오버헤드를 축소하였다. 논문서 설계된 안전한 FTP는 전자상거래 등의 여러 응용에서 활용될 수 있을 것이다.