• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.226-237
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• 1998

In recent SATCOM systems, transparent transponders are widely used. The transponder is, however, the most vulnerable part in SATCOM systems against jamming interference. All signals within the transponder bandwidth are frequency-converted and retransmitted with IM(intermodulation) products. In this paper, the method is proposed that makes the SJR(Signal-to-Jammer ratio) better. The bandwidth spreading of the user signal can reduce the jammers effects. The geostationary satellite system is modeled to simulate and to certificate the capability of suppression of jammers by DSSS. If signal is partially-overlapped by jammer and PG(processing gain) is 16.9 [dB] for 2ASK jammer and about 16.8 [dB] for QPSK jammer, when BER is $10^{-3}$.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.237-242
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• 2006

Currently, the settlement system which is used at credit card settlement from the member store of the off-line credit card is composed of the credit card settlement terminal, the VAN company which does a settlement relay service and the credit card company. When the obstacle occurs from the credit card company, the VAN company which does a settlement relay service conducts an approval vicarious execution, but when the obstacle occurs from the VAN company, the credit card settlement service is not accomplished smoothly. The dissertation implement the credit card settlement system which receives a settlement relay service that credit card settlement terminal uses a Telegram Conversion Agent from the other VAN company when the VAN company obstacle occurs.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1423-1428
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• 2012

In this paper, we investigated an implementation of anti-fire monitoring system based on the RS-485 communication to support local area coverage within a range of 1 Km range. We developed a Multi Point Communication Protocol supporting input/output information processing and control up to 8128 terminal check points, which provides an interface between the anti-fire monitoring system receiver and multiplex transponders. Additionally, a multiplex transponders controller has been designed for the implemented system to comply with the government regulation on fire protection, especially to monitor, report and control 1016 terminal check points within the time limit.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.339-344
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• 2005

Currently the credit card settlement system which is used from off-line credit card joining point is composed of the credit card settlement terminal, the VAN company which do settlement relay service and the credit card company. When the credit card company occurs obstacle, the service VAN company executes as proxy an approval and it controls. When the service VAN company occurs obstacle, the credit card settlement service does not become accomplished in the normality. The dissertation which it sees when the service VAN company occurs obstacle, the possibility of doing a settlement relay service from the different VAN company in order to be, proposed the credit card settlement system which uses the Switching Agent.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.47-53
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• 2007

The purpose of IEEE 802.16j is to extend coverage and to enhance throughput by using relay station additionally to conventional IEEE 802.16e . The cellular system experiences performance degradation at the cell edge due to pathloss, shadow and multipath fading. We can get advantage of spatial diversity gain by using relays more than two cooperatively in the IEEE 802.16j system. Cooperative relaying using space-time code provides better performance under multipath fading and has more robustness against the shadow fading than single relaying. In this paper, we investigate the performance of IEEE 802.16j using cooperative relaying by link level simulation. We also show that the cooperative relaying system achieves better performance than the conventional single relaying system. We apply realistic shadow model considering correlations between shadow fadings of different relaying paths. It is shown that the performance of the system depends highly on the spatial location of relay stations.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.110-116
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• 2013

The amplification rate of a RF repeater is limited by the feedbacked signals from the same repeater. And an ICS (Interference Cancellation System) repeater has been developed to remove the feedbacked signals. The ICS repeater estimates the amplitudes and the phases of the feedbacked signals and removes the estimated feedback signals from the received input signal of the repeater. However, it requires lots of hardware complexity and this leads to the increase the cost of the repeater. Moreover, the ICS repeater can not solve the pilot pollution problems. To solve these problems, we have studied the implementation and adaptation of smart antenna system for RF repeaters. We have designed a smart antenna system with a switching beam structure in order to reduce the hardware and computational complexity. After analyzing the proposed smart antenna system, we found out that the amplification rate of the proposed repeater increases 23dB compare to the amplification rate of ICS repeater and the output SINR increases 6dB compare to the ICS repeater.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.106-112
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• 2007

A new space-time cooperative communication relaying strategy with assistant or management terminals is proposed in multi-hop wireless communication systems. More than one relaying terminals are included in one cooperative group to share the state information such as frame error rate and channel information. Among the cooperative group, the best ones are selected to send bit information using space-time codes. An implementation for the proposed scheme is also presented using a TDMA cooperative protocol. Receive signal to transmit signal ratio($E_r/E_s$) and computer simulation show the strategy outperform the conventional cooperative system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.109-114
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• 2007

A new space-time cooperative communication relaying strategy with assistant or management terminals is proposed in multi-hop wireless communication systems. More than one relaying terminals are included in one cooperative group to share the state information such as frame error rate and channel information. Among the cooperative group, the best ones are selected to send bit information using space-time codes. An implementation for the proposed scheme is also presented using a TDMA cooperative protocol. Receive signal to transmit signal ratio($E_r/E_s$) and computer simulation show the strategy outperform the conventional cooperative system.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.147-152
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• 2022

This study describes the design and implementation of EGSE for Dehop/Rehop Transponder. The EGSE is a equipment that evaluates Dehop/Rehop Transponder and requires precise and accurate measurement. EGSE consists of a PLDIU and IIU(Instrument Interface Unit), Up/Down converter for L band, Modems to verify the Dehop/Rehop Transponder. The EGSE was used for performance verification and space environment test such as thermal vacuum after developing Dehop/Rehop Transponder.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.52-54
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• 2002

최근 하루가 다르게 증가하는 이동전화 가입자의 통화 품질을 보장하기 위해CDMA중계기의 중요도가 증가하고 있으며 자동화된 모니터링 시스템의 필요성이 대두되었다. Embedded Internet하에 CDMA중계기를 임베디드 리눅스 시스템과 연동하여 리눅스 커널 레벨에서의 모니터링 방안으로 EKMM(Embedded internet based Kernel level Monitoring Modules)시스템을 제시한다. 본 시스템은 SA-1110 마이크로 프로세스로 구현된 하드웨어에 시리얼 디바이스 드라이브와 네트웍 디바이스 드라이브를 설계하였다. 또한 리눅스 커널을 재구성하며 동적 로딩 방식으로 EKMM이 탑재되어 기존의 중계기 임베디드 시스템 보다 기능 확장성이 뛰어나고 성능이 향상된 중계기 모니터링 시스템을 설계 구현하였다.