• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.856-867
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• 2018

This paper presents the applicability of MIMO joint decoding to dual-contact satellite systems in which two LEO satellites using X-band frequency band are transmitting each image data to two ground station antennas, simultaneously. When two satellites are closely positioned within the looking angle of the two antennas, each satellite interferes with each other by the relative antenna gain corresponding to an offset angle and this might cause the performance degradation without interference mitigation. To mitigate the performance degradation, SM MIMO techniques for joint decoding are applied. Especially, the relative antenna gain of ground station depending on the angle difference between two satellites in ground station antenna plays an important role in modelling the dual-contact satellite systems. The condition number of MIMO channel including the antenna gain calculated from the mathematical gain pattern model was primarily analyzed. Simulation results showed that the SM MIMO techniques using detection schemes such as ZF-SIC, MMSE-SIC, and ML can be applicable to dual-contact satellite systems.

• Journal of the Korea Computer Industry Society
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• v.2 no.10
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• pp.1253-1260
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• 2001

In this paper, a new voltage-controlled tunable analog active element for low-voltage applications and information protection is proposed. The proposed active element is composed of the CMOS complementary cascode circuit which can extend transconductance of an element. Therefore, the unity gain frequency which is determined transconductance is increased than that of the conventional element. And then these results are verified by the $0.25\mutextrm{m}$ CMOS n-well parameter HSPICE simulation. As a result, the gain and the unity gain frequency are 42㏈ and 200MHz respectively in the element on 2V supply voltage. And power dissipation of the designed circuit is 0.32mW.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.826-829
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• 2007

In this paper, we proposed two systems, STTC scheme and STBC based on STTC scheme, to enhance the reliability of HDR-WPAN system and analyzed BER(bit error rate) performance of the proposed systems over the slow fading channel. The proposed systems obtained a diversity gain and coding gain without increasing an additional channel bandwidth. However, in terms of reliability, about 4dB improvement at $BER=10^{-3}$ was obtained by the STBC based on STTC scheme because of the additional diversity gain of STBC. From these results, STBC based on STTC scheme was more appropriate to improve the reliability and channel efficiency of HDR-WPAN system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.617-623
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• 2005

In this paper, new space-time block codes achieving full rate and full diversity for QAM and quasi-static Rayleigh fading channels when using 3 transmit antennas are proposed. These codes are constructed by serially concatenating the constellation rotating precoders with the Alamouti scheme like the conventional A-ST-CR code Computer simulations show that all of the proposed codes achieve the coding gains greater than the existing ST-CR code, in which the best has approximately 1.5dB and 3dB larger coding gains than the ST-CR code for QPSK and 16-QAM, respectively, at average SER= 10$^{-5}$.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.319-324
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• 2003

In this paper, a new wideband tunable analog element for multimedia system is proposed. The proposed active element is composed of the complementary cascode circuit which can extend transconductance of an element. Therefore, the unity gain frequency which is determined transconductance is increased than that of the conventional element. And then these results are verified by the 0.22$\mu\textrm{m}$ CMOS n-well parameter simulation. As a result, the gam and the unity gam frequency are 42dB and 200MHz on 2V supply voltage. And power dissipation of the designed element is 0.32mW.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.555-556
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• 2015

MPEG 의 Royalty-Free 비디오 코덱의 하나로 표준화 중인 IVC(Internet Video Coding)에서는 화면내(intra) 예측부호화에서 부호화 이득을 위하여 $4{\times}4$ 블록 예측 및 $4{\times}4$ 블록 변환을 포함하고 있다. 반면, 화면간(inter) 예측부호화에서는 $16{\times}16$ 블록에서 최소 $8{\times}8$ 블록까지의 가변크기 블록에 대한 예측만 가능하다. 보다 복잡한 영상의 경우 보다 작은 블록에 대한 화면간 예측을 통하여 부호화의 성능 개선을 개선할 수 있다. 본 논문에서는 기존의 화면간 예측의 블록 크기를 $4{\times}4$ 블록까지 확장하여 화면간 예측부호화 성능을 개선한다. 실험결과 제안기법은 기존의 ITM 12.0 대비 다양한 테스트 시퀀스의 휘도성분에서 평균적으로 비트율 절감의 이득은 없으나 대부분의 클래스에서 성능개선을 보였고 추가적인 최적화가 필요함을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.10
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• pp.956-964
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• 2012

An opportunistic interference alignment based on dynamic cell selection is proposed. Since the proposed method can switch the desired signal space and the interference space of received signals, an additional selective diversity gain increases. The performance analysis using probabilistic models provides a mathematical expression for the sum-rate capacity. Simulation examples show that the proposed method achieves the higher sum-rate capacity than that of the conventional opportunistic interference alignment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.301-303
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• 2016

This paper proposes a method providing diversity gain using small base stations in a cell coverage in order to improve diversity gain. The small base stations and the conventional base station consist a virtual MIMO array by using the cooperative communication scheme. Also, transmission diversity scheme is applied. A mobile user can receive the signals having the improved reliability by the applied transmission diversity scheme and the cooperative communication scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.913-916
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• 2005

In this study, an additional microstrip patch with a comb-pattern slot is positioned on the conventional single layer microstrip patch antenna. Numerical results of the antenna bandwidth and the antenna gain are increased compared with those of the conventional single layer microstrip patch antenna.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.707-707
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• 2012

현재 농업용저수지 둑 높이기 사업이 전국 110개 저수지를 대상으로 추진되고 있다. 다양한 효과가 기대되고 있는 둑 높이기 사업과 더불어 농업생산기반시설 및 주변지역 활용에 관한 특별법의 시행으로 저수지 등 농업기반시설 및 그 주변지역을 본래의 기능을 유지하는 범위에서 개발할 수 있게 됨에 따라 다양한 시설물의 설치와 운영을 통해 지역의 수익창출이 가능하게 되었다. 그러나 저수지 수변지역으로 개발계획이 집중되어 있고 추가확보 되는 용수는 하천유지와 농업용수 공급에 주로 활용될 계획이므로 추가확보 용수의 보다 다양한 활용방안을 제고하여 더 많은 이익을 창출할 수 있는 방안이 요구되고 있다. 그 중 하나로 둑 하류지역 농경지의 관개배수체계를 정비하여 추가용수 이용의 효율을 향상시키고 농촌마을과 연계하여 친수공간을 조성함으로서 둑하류 농촌마을 주민의 삶의 질 향상과 경제적 이득을 창출할 수 있는 기회를 제공할 수 있을 것이다. 이와 같은 친수공간 개발은 둑높이기 저수지의 추가용수 확보규모 및 지역의 지형, 토지이용, 사회경제적 특성에 따라 달라질 수 있으나 유형화를 통해 대표적 특성에 대한 표준안을 개발 할 수 있을 것이다. 따라서 본 연구에서는 기초연구로서 둑 높이기 저수지의 특성 및 주변 현황자료를 수집하고 통계적인 기법을 이용하여 5개의 둑하류 농촌지역 친수공간 개발유형을 분류하였으며 지역 및 공간적 분포를 제시하였다.