• Title/Summary/Keyword: General odd correlation

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Polyphase Signature Sequences for M-ary Phase Signaling (M진 위상 신호 방식에 효과적인 다상 서명 수열)

  • Park, So-Ryoung;Song, Iick-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.11C
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    • pp.1059-1065
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    • 2007
  • In this paper, we propose a class of polyphase signature sequences, whose general odd correlation properties are useful for M-ary phase signaling systems. The maximum magnitude of the general odd correlation functions of the proposed sequences are investigated and compared with those of FZC (Frank-Zadoff-Chu) sequences and those of EOE (equivalent odd and even correlation) sequences. The performance of the asynchronous M-ary phase signaling systems using the proposed sequences is simulated and compared with that using FZC sequences in direct sequence code division multiple access (DS/CDMA) systems. The performance of the system using the proposed sequence is shown to be better than that using FZC sequences when the multipath fading is in existence.

DS/CDMA Signature Sequences for 4-phase Signaling (4-위상 신호 방식에 알맞은 직접수열 부호분할 다중접속 서명수열)

  • Park So Ryoung;Song Iickho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.5C
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    • pp.313-319
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    • 2005
  • In this paper, we propose a class of polyphase signature sequences, whose general odd correlation properties are useful for 4-phase signaling systems. The performance of the direct sequence code division multiple access (DS/CDMA) systems using the proposed sequences is compared with that using binary pseudo-noise sequences. The performance of the system using the proposed sequence is shown to be better than that using other conventional sequences both from the worst-case analysis and bit error rate simulations.

Leakage Current Waveforms of Outdoor Polymeric Insulators and Possibility of Application for Diagnostics of Insulator Conditions

  • Suwarno Suwarno
    • Journal of Electrical Engineering and Technology
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    • v.1 no.1
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    • pp.114-119
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    • 2006
  • This paper reports the investigation results on the leakage currents (LC) on polymeric outdoor insulators. The samples used were EPDM (ethylene prophylene diene monomer) insulators used at 20 kV distribution lines. AC voltage was applied and the LC waveforms were measured under various environmental conditions (humidity and pollution). Digital data of the LC was transferred from a digital storage oscilloscope to a computer for further analysis. The LC waveform parameters such as magnitude and harmonic content (as indicated by the total harmonic distortion (THD)) were analyzed. The experimental results showed that 3rd, 5th and 7th harmonics and higher odd harmonics were observed for symmetrical-distorted LC waveforms while for unsymmetrical-distorted LC waveforms, odd and even harmonics were observed. The LC analysis indicated that there are 5 stages of insulator conditions from normal condition up to flashover correlated with different kind of LC waveforms. The results also showed that in general the magnitude of LC was good enough to show the condition of the insulators. However, under discharge condition (for example as a result of dry band arching) the LC magnitude should be combined by the THD to show a better correlation with the insulator condition. The product between THD and LC magnitude may be used as a diagnostic parameter.

New Families of p-ary Sequences With Low Correlation and Large Linear Span (낮은 상관 특성과 큰 선형 복잡도를 갖는 새로운 p-진 수열군)

  • Kim, Young-Sik;Chung, Jung-Soo;No, Jong-Seon;Shin, Dong-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.7C
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    • pp.534-539
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    • 2008
  • For an odd prime p, n=4k, and $d=((p^{2k}+1)/2)^2$, Seo, Kim, No, and Shin derived the correlation distribution of p-ary m-sequence of period $p^n-1$ and its decimated sequences by d. In this paper, two new families of p-ary sequences with family size $p^{2k}$ and maximum correlation magnitude $[2]sqrt{p^n}-1$ are constructed. The linear complexity of new p-ary sequences in the families are derived in the some cases and the upper and lower bounds of their linear complexity for general cases are presented.

Photochemical Analysis of Ozone Levels in the Gulf of Gwangyang in the Spring and Summer of 2009 (2009년 봄, 여름철 광양만 지역 오존의 광화학적 특성 분석)

  • Shon, Zang-Ho;Song, Sang-Keun;Lee, Gang-Woong
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.2
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    • pp.161-176
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    • 2010
  • We examined high ozone episodes observed during the intensive measurement periods (11 May~21 June and 30 July~11 August 2009) in the Gulf of Gwangyang. During that period, there were a few events (or days) in which 1 hr averaged ozone concentrations were greater than 100 ppbv. The analysis of ozone budget and photochemical characteristics related to the ozone production was carried out using a photochemical box model. Ozone sensitivity to $NO_x$ and VOCs was also examined in the study area during the measurement period. Diurnal variation of ozone during the episodes was similar to that of odd hydrogen radicals ($HO_2,CH_3O_2$, and $RO_2$), suggesting significant correlation with photochemical production of ozone during the episodes. In general, ozone concentration in the study area during the measurement period was sensitive to VOCs, whereas ozone was sensitive to $NO_x$ under certain conditions. Ozone sensitivity assessment using a radical budget analysis and $NO_x$/VOCs-control strategy was consistent with that using indicator species ($H_2O_2/HNO_3$ ratio).