• International Journal of Industrial Entomology and Biomaterials
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• 제13권2호
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• pp.73-77
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• 2006

Combining ability and hybrid vigour analysis was carried out in hybrids between newly developed non-susceptible lines to BmDNV1 and popular bivoltine breeds for certain quantitative traits viz. Pupation rate, Cocoon yield, Cocoon weight, Cocoon shell weight and Cocoon shell ratio, Survival rate against BmIFV and BmNPV. General combining ability (GCA) effects revealed that among the lines CSR2DR was found good general combiner exhibiting significant GCA effects for six characters, out of seven traits evaluated. Among testers CSR28DR was found as good combiner exhibiting significant GCA effects for six traits. Out of 36 hybrids made between $resistant{\times}resistant,\;resistant{\times}susceptible\;and\;susceptible{\times}susceptible$ breeds, one hybrid $CSR21DR{\times}CSR28DR$ exhibited significant SCA effects for six traits. The selected hybrid $CSR21DR{\times}CSR28DR$ also exhibited significant positive heterosis and heterobeltiosis expressions for maximum traits and could be exploited as commercial silkworm hybrid resistant to important viral diseases.

• 한국인터넷방송통신학회논문지
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• 제14권5호
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• pp.67-72
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• 2014

본 논문에서는 협력 통신에 에너지 하베스팅 기법을 적용할 경우 발생되는 잡음을 최소화하고 성능을 개선시킬 수 있는 방안을 제안하였다. 제안된 기법은 에너지 하베스팅 노드에서 수집된 전력을 저장하고 저장된 전력을 바탕으로 중계기를 사용한다. 이때, 중계기에서는 복호 후 전송(Decode and Forward) 기법을 적용하여 잡음의 영향을 최소화하였고, 수신단에서는 최대비 결합(Maximal Ratio Combining) 기법을 적용하여 다이버시티 이득을 얻었다. 따라서 제안된 기법을 일반적인 네트워크 환경에 적용할 경우 중소형 중계기의 구동에 필요한 전력을 제거할 수 있으며, 전력의 수집으로 인해 단말기 및 네트워크의 효율성을 증가시킬 수 있다. 마지막으로, 제안한 프로토콜을 레일리 페이딩 환경에서 전력 수집 효율 및 비트오류율(Bit Error Rate), 아웃티지 확률(Outage Probability)을 통해 시스템의 성능을 평가한다.

• 대한전자공학회논문지TC
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• 제40권4호
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• pp.45-53
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• 2003

본 논문에서는 공간 푸리에 변환과 최대비 결합 알고리즘을 사용한 새로운 방식의 스마트 안테나 수신기를 제안한다. 제안된 방식은 공간 푸리에 변환을 채용하여 수신 신호를 여러 개의 입사각 방향성분으로 분리하였고, 최대비 결합 알고리즘을 사용하여 원하는 사용자 신호 성분의 신호대 잡음비가 극대화 될 수 있도록 하였다. 제안된 알고리즘을 CDMA 역방향 링크의 수신기와 결합하여 성능 개선 효과를 확인하기 위한 모의 실험을 실시하였으며 그 결과 빔 패턴에 대한 집중화 효과를 확인할 수 있었다. 이로써 제안된 방식의 스마트 안테나 시스템이 기존의 스마트 안테나 시스템과 동일한 성능 개선 효과를 가져다 줄 수 있음을 확인할 수 있었다. 모의 실험은 백색잡음 환경에서 수행되었으며 신호의 입사각에 따른 빔 패턴의 집중화 정도와 최대비 결합의 수에 따른 비트 오류 성능 개선 정도를 확인해 보았다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.650-655
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• 2001

Wind speeds can vary rapidly and wind turbines cannot easily follow these variations because of their inertia and aerodynamic characteristics. For maximum energy extraction. the turbine blades should operate at their optimum tip speed ratio, but with rapid changes in wind speed. this is usually not possible. To improve the energy extraction from turbulent wind, it is necessary to establish an effective measure of the high frequency component of the wind. and then to use this measure to optimise the operation of the turbine controller for maximum energy extraction. This paper presents an approach for combining readings from three anemometers into a composite wind speed measurement. and using this signal to control the operation of a permanent magnet generator to achieve maximum energy extraction. The method combines simulation and experimental investigations into a heuristic algorithm. and demonstrates its effectiveness with field trials.

• Journal of Communications and Networks
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• 제18권3호
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• pp.288-298
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• 2016

Proactive relay selection in cognitive radio networks has recently received considerable attention. However, its outage probability analysis is limited to partially-identical fading distributions, uncorrelation among received signal-to-noise ratios (SNRs), and no direct channel. This paper completes this literature deficiency by generalizing the existing analysis for non-identical fading distributions, correlation among received SNRs, and with direct channel. Numerous results demonstrate that relay selection with a direct channel achieves a higher diversity order and superior performance than that without a direct channel at virtually no cost of power and bandwidth. Further, proactive relay selection suffers an error floor at either a large maximum transmit power or large maximum interference power; however, the error floor level can be significantly remedied with an increase in the number of relays.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.41-44
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• 2002

Alamouti proposes a two branch transmit diver-sity scheme that provides the same diversity order as maximal ratio combining at the receiver. It has many advantages of no bandwidth expansion, not requiring channel information at the transmitter and simple maximum likelihood decoding at the receiver. Papadias and Foschini extend this sch-eme to four transmit antennas and suggest several schemes to decrease the interference component and allow the attainment of the open-loop capacity. This paper shows the performance of ZF and MM-SE schemes comparing with ideal case on 4xl sy-stem over BER and 10% outage capacity.

• Journal of Communications and Networks
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• 제8권1호
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• pp.38-48
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• 2006

A synchronous multicarrier (MC) code-division multiple access (CDMA) system using inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) for the downlink mobile communication system operating in a frequency selective Rayleigh fading channel is analyzed. Both carrier frequency offset and timing offset are considered in the analysis. Bit error rate performance of the system with both equal gain combining and maximum ratio combining are obtained. The performance is compared to that of the conventional system using correlation receiver. It is shown that when subcarrier number is large, the system using IFFT/FFT has nearly the same performance as the conventional one, while when the sub carrier number is small, the system using IFFT/FFT will suffer slightly worse performance in the presence of carrier frequency offset.

• Journal of electromagnetic engineering and science
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• 제7권4호
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• pp.201-206
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• 2007

When the M-ary signal experiences the Rayleigh fading, the diversity schemes can reduce the effects of fading since the probability that all the signals components will fade simultaneously are reduced considerably. The symbol error probabilities for various M-ary signals, such as MDPSK, MPSK and MQAM, are mathematically derived for the SC-2(Selection Combining 2) demodulation system, whereby the two signals with the two largest amplitudes are coherently combined among the L branches. On the other hand, maximum ratio combining(MRC) requires the individual signals from each path to be time-aligned, cophased, optimally weighted by their own fading amplitude, and then summed. The propagation model used in this paper is the frequency-nonselective slow Rayleigh fading channel corrupted by the Additive White Gaussian Noise(AWGN). The numerical results presented in this paper are expected to provide information for the design of radio system using M-ary modulation method for above mentioned channel environment.

• 한국전자파학회지:전자파기술
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• 제6권3호
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• pp.75-79
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• 1995

This paper derives the symbol error rate (SER) for quadrature amplitude modulation (QAM) with L-fold selection combining (SC) space diversity in Rayleigh fading channel. No analysis has been reported yet for theoretical SER performance of QAM with SC space diversity in Rayleigh fading channels. The formula is obtained by averaging the symbol error probability of M-ary QAM in an additive white Gaussian noise channel over the distribution of the maximum signal-to-noise ratio among all of the diversity channels. By giving the order of diversity, L, and the number of signal points, M, we have been able to obtain the SER performance of QAM with general SC space diversity. Analytical results show that the probability of error decreases with the order of diversity. We can also see that the incremental diversity gain per additional diversity decreases as the number of branches becomes larger.

• 대한전자공학회논문지TC
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• 제44권12호
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• pp.28-33
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• 2007

느린 페이딩 패널에서 공간-시간 트렐리스 부호화된 OFDM 시스템을 제안하고, 시간 영역에서 제안된 principal ratio combining(PRC)와 일반화된 PRE(GPRC)의 수식을 이론적으로 주파수 영역에서 새롭게 분석한다. 시간영역에서와 마찬가지로 GPRC 기법은 ML 및 PRC 기법을 분할하여 성능과 수신기 복잡도 간의 유연한 tradeoff를 활용할 수 있다. M진 PSK 변조 방식을 이용하는 컴퓨터 시뮬레이션을 통해 주파수 플랫 및 주파수 선택적 페이딩에서 성능을 검증한다. 또한 세 가지 수신 기법간의 수신기 복잡도와 시뮬레이션 시간을 비교 검토한다.