• Title/Summary/Keyword: DS-SS

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A study of noise reduction for reliable data transmisstion in PLC (전력선 통신 환경에서의 신뢰성 있는 데이터 전송을 위한 잡음제거에 관한 연구)

  • Lee, Hong-Hee;Kim, Gwan-Su
    • Proceedings of the KIPE Conference
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    • 2001.07a
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    • pp.642-645
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    • 2001
  • 본 논문에서는 전력전달 매체인 전력선을 이용하여 신뢰성 있는 통신환경을 구축하기 위해 필요한 전력선 통신 시스템에서의 임피던스, 잡음, 특성 등을 고찰했다. 이를 바탕으로 기존 네트워크에 사용 되어온 DS-SS(Direct sequence-Spread Spectrum) 기법을 전력선 통신에 적용하여 전력선통신 시스템을 구성하고 다중 액세스 기법인 CSMA를 적용하여 시스템 효율에 대한 성능 평가를 하였다.

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Code synchronization technique for spread spectrum transmission based on DVB-RCS +M standard (DVB-RCS +M 표준기반의 대역확산기술 부호동기기법)

  • Kim, Pan-Soo;Chang, Dae-Ig;Lee, Ho-Jin
    • Journal of Satellite, Information and Communications
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    • v.4 no.2
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    • pp.39-45
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    • 2009
  • This paper proposes the specific code synchronization technique for DS-SS(Direct Sequence-Spread Spectrum transmission in the DVB-RCS +M standard. DS-SS is better than multi-carrier transmission method under nonlinear channel but imposes a long acquisition time. To improve the synchronization aspect, the robust correlation structure is introduced for acquisition and the nonlinear delay lock loop is done for tracking. MAT(Mean Acquisition Time) performances is shown to validate its superiority. In addition, code tracking and jitter performances are done when code tracking algorithm based on 2 oversamples which is not influenced by sampling clock timing offset and carrier freq. offset is used.

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Decision Statistics for Noncoherent Serial PN Code Acquisition In Chip-Asynchronous DS/SS Systems (칩비동기 직접수열 대역확산 시스템에서 비동기 직렬 의사잡음코드 포착을 위한 결정통계량)

  • 윤석호;김선용
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.5
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    • pp.19-25
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    • 2004
  • In this paper, we propose optimal and suboptimal serial code acquisition schemes for chip-asynchronous direct-sequence spread-spectrum systems. The conventional serial code acquisition scheme is to compare each value of correlator outputs with a threshold individually. However, such a scheme is optimum only under the chip-synchronous assumption which is actually very difficult to be held prior to acquisition at the receiver because the signal-to-noise ratios before despreading are very low. In this paper, an optimal serial code acquisition scheme is derived based on the maximum-likelihood criterion under the more realistic and general chip-asynchronous environments. A suboptimal scheme, which is simpler but yields comparable performance to the optimal one, is also derived based on the criterion of local detection power Numerical results show that, under the chip-asynchronous environments, both the optimal and suboptimal serial code acquisition schemes outperform the conventional serial code acquisition scheme.

Performance of Adaptive Correlator using Recursive Least Square Backpropagation Neural Network in DS/SS Mobile Communication Systems (DS/SS 이동 통신에서 반복적 최소 자승 역전파 신경망을 이용한 적응 상관기)

  • Jeong, Woo-Yeol;Kim, Hwan-Yong
    • The Journal of the Acoustical Society of Korea
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    • v.15 no.2
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    • pp.79-84
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    • 1996
  • In this paper, adaptive correlator model using backpropagation neural network based on complex multilayer perceptron is presented for suppressing interference of narrow-band of direct sequence spread spectrum receiver in CDMA mobile communication systems. Recursive least square backpropagation algorithm with backpropagation error is used for fast convergence and better performance in adaptive correlator scheme. According to signal noise ratio and transmission power ratio, computer simulation results show that bit error ratio of adaptive correlator uswing backpropagation neural network improved than that of adaptive transversal filter of direct sequence spread spectrum considering of co-channel and narrow-band interference. Bit error ratio of adaptive correlator using backpropagation neural network is reduced about $10^{-1}$ than that of adaptive transversal filter where interference versus signal ratio is 5 dB.

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A Study on Filtration Effect of Anaerobic Digestion Wastewater by Composition of Filtration Layer Materials (퇴비단 여과재 구성에 따른 혐기소화액 여과 효과)

  • Lee, Dong-Hyun;Jeong, Kwang-Hwa;Khan, Modabber Ahmed;Kim, Jung-Gon;Kwak, Jung-Hun;Ahn, Heekwon;Kim, Eun-Jong
    • Journal of Animal Environmental Science
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    • v.19 no.1
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    • pp.39-46
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    • 2013
  • This study was carried out to compare the filtration effect of anaerobic digestion waste water by compost filtration bed. Three types of filtration systems were set for filtration test following to composition of bedding materials. Two filtration systems were filled with sawdust, rice-hull and wood-chip. And the other was filled with sawdust and rice-hull. Anaerobic digestion waste water was applied evenly on the surface of the filtration bed with spraying nozzle. The concentration of nitrogen, biochemical oxygen demand (BOD), suspended solids (SS) of anaerobic digestion waste water was decreased by filtration treatment. The total nitrogen content was decreased from 1,313 mg/L to 1,090~1,293 mg/L and BOD concentration was decreased from 529.7 mg/L to 125~162.3 mg/L, respectively. The SS content was decreased from 69~79% by filtration process. In addition, the electrical conductivity (EC) was decreased from 10.22 ds/m to 7.91~8.31 ds/m.

Improvement of DS Simple Reception System for Advance of Duty Rate on Meteor Burst Transmission Path (유성 버스트 전송로의 도통을 향상을 위한 DS 간이 수신시스템의 개선)

  • Kwon Hyeog-Soong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.11A
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    • pp.1073-1080
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    • 2005
  • In spite of many advantages of Meteor Burst Communications(MBC) on its transmission channel, the fact that its duty rate is less than 10 percents is a considerable deficiency of MBC. To overcome with this deficiency without paying large cost, we use a direct sequence(DS) simple reception system. This method doesn't need to add the components for acquisition or tracking the signal so that it keeps the cost efficiency of the MBC. But it has a disadvantage that its duty rate shows a large decline by noise. For this problem, we adopt the proposed system applying a positive feedback circuit. The improvement by this method is more significant when the received signal is weak. Simulation results show as tl is l00ms, then the burst length would be increased by $35\%$ when the initial value of the received signal power increases by 3 dB, t2 is 135ms. If the power increases by 6dB the burst length would be 170ms thus increased by $70\%$, which shows a great enhancement. Suppose now that tl is 50ms and the power is increased by 3dB, then t2 would be increased by $70\%$ to 85ms, and increasing the power by 6dB it would be increased by $130\%$ to 115ms.

Molecular Analysis of Geminigirus ORFs on Symptom Development

  • Park, Eulyong;Hyunsik Hwang;Lee, Sukchan
    • The Plant Pathology Journal
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    • v.15 no.1
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    • pp.38-43
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    • 1999
  • Mutants of the monopartite geminivirus beet curly top virus (BCTV) have been screened for infectivity, systemic movement, replication and symptom development in Arabidopsis thaliana. As known by coding for coat protein, R1 mutant was not infectious and did not move systemically. R2, R3 and L2/L3 mutants produced milder symptoms compared to wild type BCTV but the infectivity was reduced by 40% to 60%. R2 ORF is thought to be involved in the regulation of ssDNA and dsDNA accumulation because only dsDNA was accumulated on R2-infected organs. Disruption of ORF L4 resulted in reduced infections, but the viral DNA was accumulated in infected organs from roots to shoot tips as much as wild type BCTV on Sei-O. In addition, 4 mutants did not produce callus-like tissues on infected organs, suggesting that L4 ORF may play a role in the induction of host cell divisions by virus infection. This result was supported by the patterns of mRNA expression and promoter analysis of the cell cycle marker gene, cycl, on Arabidopsis. cycl mRNA was accumulated on symptomatic organs by wild type BCTV infections but not by L4 mutant. We conclude that the BCTV L4 ORF is essential for symptom developments, specially callus-like formation on infected organs.

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Cohesion Establishment Factors Stimulate Endonuclease Activity of hFen1 Independently and Cooperatively

  • Kim, Do-Hyung;Kim, Jeong-Hoon;Park, Byoung Chul;Cho, Sayeon;Park, Sung Goo
    • Journal of Microbiology and Biotechnology
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    • v.25 no.10
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    • pp.1768-1771
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    • 2015
  • Human Fen1 protein (hFen1) plays an important role in Okazaki fragment processing by cleaving the flap structure at the junction between single-stranded (ss) DNA and doublestranded (ds) DNA, an intermediate formed during Okazaki fragment processing, resulting in ligatable nicked dsDNA. It was reported that hChlR1, a member of the cohesion establishment factor family, stimulates hFen1 nuclease activity regardless of its ATPase activity. In this study, we found that cohesion establishment factors cooperatively stimulate endonuclease activity of hFen1 in in vivo mimic condition, including replication protein-A-coated DNA and high salt. Our findings are helpful to explain how a DNA replication machinery larger than the cohesion complex goes through the cohesin ring structure on DNA during S phase in the cell cycle.

The effect of negative bias stress stability in high mobility In-Ga-O TFTs

  • Jo, Kwang-Min;Sung, Sang-Yun;You, Jae-Lok;Kim, Se-Yun;Lee, Joon-Hyung;Kim, Jeong-Joo;Heo, Young-Woo
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2013.05a
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    • pp.154-154
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    • 2013
  • In this work, we investigated the characteristics and the effects of light on the negative gate bias stress stability (NBS) in high mobility polycrystalline IGO TFTs. IGO TFT showed a high drain current on/off ratio of ${\sim}10^9$, a field-effect mobility of $114cm^2/Vs$, a threshold voltage of -4V, and a subthresholdslpe(SS) of 0.28V/decade from log($I_{DS}$) vs $V_{GS}$. IGO TFTs showed large negative $V_{TH}$ shift(17V) at light power of $5mW/cm^2$ with negative gate bias stress of -10V for 10000seconds, at a fixed drain voltage ($V_{DS}$) of 0.5V.

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Orthogonal Reception Characteristics for the DS/SS Signals with Time-shifted m-Sequences

  • Baek Kyung Hoon;Hyun Kwang Min;Yoon Dong Weon;Park Sang Kyu
    • Proceedings of the IEEK Conference
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    • 2004.08c
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    • pp.658-662
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    • 2004
  • This paper proposes an orthogonal reception structure for OS/SS communication with time-shifted m-sequences, and compares the performances of the proposed and conventional receiver. This structure provides two important characteristics to reference user signal with not only increment of auto-correlation value but also cancel of the cross-correlation value out to zero between the reference user and other user signals. In addition, the structure can be easily implemented with the conventional receiver adding an additional integrator path in parallel and an adder that sums the conventional path output and the new path output signal. Hence, the proposed structure can be applied for channel impulse response measurement, and efficiently used for multi-user interference signal cancellation and channel capacity increment by flexible structural inter-working operation, connection or disconnection, of the new path to conventional receiver structure.

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