• Title/Summary/Keyword: peak set

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On the Near Optimal PRT Set of TR Scheme for PAPR Reduction in OFDM System (OFDM 시스템의 PAPR 감소를 위한 TR 방법의 준 최적 PRT 집합 선택에 관한 연구)

  • Lim, Dae-Woon;Noh, Hyung-Suk;No, Jong-Seon;Shin, Dong-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.2C
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    • pp.174-180
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    • 2007
  • In the tone reservation (TR) scheme, it is known that the set of randomly selected peak reduction tones (PRT's) performs better than the contiguous PRT set and the interleaved PRT set in the PAPR reduction of orthogonal frequency division multiplexing (OFDM). It is also known that finding the optimal PRT set corresponds to the secondary peak minimization problem in the TR scheme. However, the problem cannot be solved for the practical number of tones since it is NP-hard. In this paper, a new search algorithm for the near optimal PRT set is proposed based on the fact that the secondary peak value of the PRT set statistically tends to decrease asthe variance of the PRT set decreases.

A NOTE ON THE CHOQUET BOUNDARY OF TENSOR PRODUCTS

  • Hwang, Sun-Wook;Kwon, Oh-Sang
    • The Pure and Applied Mathematics
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    • v.11 no.2
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    • pp.149-154
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    • 2004
  • We show that the Choquet boundary of the tensor product of two real function algebras is the product of their Choquet boundaries.

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BOUNDARIES AND PEAK POINTS OF LIPSCHITZ ALGEBRAS

  • MAHYAR, H.
    • Honam Mathematical Journal
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    • v.22 no.1
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    • pp.47-52
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    • 2000
  • We determine the Shilov and Choquet boundaries and the set of peak points of Lipschitz algebras $Lip(X,\;{\alpha})$ for $0<{\alpha}{\leq}1$, and $lip(X,\;{\alpha})$ for $0<{\alpha}<1$, on a compact metric space X. Then, when X is a compact subset of $\mathbb{C}^n$, we define some subalgebras of these Lipschitz algebras and characterize their Shilov and Choquet boundaries. Moreover, for compact plane sets X, we determine the Shilove boundary of them. We also determine the set of peak points of these subalgebras on certain compact subsets X of $\mathbb{C}^n$.

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Development of daily solar flare peak flux forecast models for strong flares

  • Shin, Seulki;Lee, Jin-Yi;Chu, Hyoung-Seok;Moon, Yong-Jae;Park, JongYeob
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.1
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    • pp.64.3-64.3
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    • 2015
  • We have developed a set of daily solar flare peak flux forecast models for strong flares using multiple linear regression and artificial neural network methods. We consider input parameters as solar activity data from January 1996 to December 2013 such as sunspot area, X-ray flare peak flux and weighted total flux of previous day, and mean flare rates of McIntosh sunspot group (Zpc) and Mount Wilson magnetic classification. For a training data set, we use the same number of 61 events for each C-, M-, and X-class from Jan. 1996 to Dec. 2004, while other previous models use all flares. For a testing data set, we use all flares from Jan. 2005 to Nov. 2013. The best three parameters related to the observed flare peak flux are weighted total flare flux of previous day (r = 0.51), X-ray flare peak flux (r = 0.48), and Mount Wilson magnetic classification (r = 0.47). A comparison between our neural network models and the previous models based on Heidke Skill Score (HSS) shows that our model for X-class flare is much better than the models and that for M-class flares is similar to them. Since all input parameters for our models are easily available, the models can be operated steadily and automatically in near-real time for space weather service.

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Electric property changes of Gravure Off-set solar cells according to firing conditions (소성조건에 따른 Gravure Off-set 태양전지의 전기적 특성변화)

  • Kim, Jung-Mo;Kim, Dong-Ju;Bae, So-Ik
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1382-1383
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    • 2011
  • 결정질 실리콘 태양전지에서 전극 형성 공정은 Voc(Open-circuit voltage), Isc(Short-circuit current), Rser(Series resistance), Rshunt(Shunt resistance), FF(Fill factor) 특성에 영향을 주기 때문에 매우 중요하다. 하지만 paste와 선 공정에서의 조건에 따라 특성이 바뀌기 때문에 소성 공정을 최적화하기는 쉽지 않다. 본 연구에서는 Gravure Off-set printing 방식을 이용하여 결정질 실리콘 기판 표면에 미세 전극 형성 공정을 하고 소성 조건 최적화를 위해 peak 온도와 ramp-up 속도를 변화시켜 각 조건별 특성을 비교하였다. Peak 온도가 커질수록, contact resistance의 감소에 따라 Rser가 줄어들었다. 본 연구를 통해 Voc는 619mV, FF는 77.9%로 측정되는 Gravure Off-set 태양전지에 최적화된 소성 공정 조건을 확보하였다.

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Adaptive TR Scheme for PAPR Reduction in OFDM Systems (OFDM 시스템의 PAPR 감소를 위한 적응적 TR 기법)

  • Lim, Dae-Woon;Noh, Hyung-Suk;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.554-561
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    • 2008
  • For the tone reservation (TR) scheme in orthogonal frequency division multiplexing (OFDM), there exists a trade-off between peak to average power ration (PAPR) reduction performance and data transmission rate. While PRT set is fixed in the conventional TR scheme, the proposed scheme adaptively select the PRT set according to the PAPR of the input OFDM symbol. It is shown that the PAPR reduction performance of the proposed scheme is better than that of the conventional scheme when the data transmission rate is the same.

A PSNR Estimation Method Exploiting the Visual Rhythm for Reconstructed Video Frames at IPTV Set-top Box (비쥬얼리듬을 이용한 IPTV Set-top Box 재생영상에 대한 PSNR 추정 기법)

  • Kwon, Jae-Cheol;Suh, Chang-Ryul
    • Journal of Broadcast Engineering
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    • v.14 no.2
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    • pp.114-126
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    • 2009
  • In this paper, we propose a PSNR(peak-to-peak signal to noise ratio) estimation method exploiting visual rhythm information for the reconstructed video frames at the customer's STB(Set-top Box). Key idea is that we can estimate the PSNR by using VR(visual rhythm) information even though a VR consists of the pixels in a vertical direction of a 2D(2-dimensional) video frame, because VR is the 1D projected version of a 2D video frame approximately. Simulation results show that the estimated PSNR from VR information is closely related to the PSNR from 2D video frames. The advantages of the proposed scheme includes that it can monitor the video quality efficiently while minimizing the computation load of STB, and show the location, duration and occurrence count of severe picture degradation.

A physically consistent stress-strain model for actively confined concrete

  • Shahbeyk, Sharif;Moghaddam, Mahshid Z.;Safarnejad, Mohammad
    • Computers and Concrete
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    • v.20 no.1
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    • pp.85-97
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    • 2017
  • With a special attention to the different stages of a typical loading path travelled in a fluid confined concrete test, this paper introduces a physically consistent model for the stress-strain curve of actively confined normal-strength concrete in the axial direction. The model comprises of the five elements of: (1) a criterion for the peak or failure strength, (2) an equation for the peak strain, (3) a backbone hydrostatic curve, (4) a transient hardening curve linking the point of departure from the hydrostatic curve to the failure point, and finally (5) a set of formulas for the post-peak region. Alongside, relevant details and shortcomings of existing models will be discussed in each part. Finally, the accuracy and efficiency of the proposed model have been verified in a set of simulations which compare well with the experimental results from the literature.

ON THE SOLAR OSCILLATOR STRENGTH OF SiH+

  • TRIVEDI CHETNA;SINHA K.
    • Journal of The Korean Astronomical Society
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    • v.29 no.spc1
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    • pp.345-346
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    • 1996
  • The contrasting values of the oscillator strengths for the (0,0) band of SiH+ molecules for the $A\;^1II-X\;^1{\sum}+$ transition reported in literature, motivated us to reinvestigate the same with the help of a new set of well accepted solar photospheric models, elemental abundances and dissociation energy.

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A Study on Uncertainty and Sensitivity of Operational and Modelling Parameters for Feedwater Line Break Analysis (급수관 파열사고 해석에 대한 운전변수와 모형변수의 불확실성 및 민감도 연구)

  • Lee, Seung-Hyuk;Kim, Jin-Soo;Chang, Soon-Heung
    • Nuclear Engineering and Technology
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    • v.19 no.1
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    • pp.10-21
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    • 1987
  • Uncertainty analysis of the FLB accident is performed for KNU-1 using the response surface methodology and Monte Carlo simulation. The FLB analyses using the RELAP4/Mod6 were performed a number of times to generate the data base for the uncertainty analysis, along with the EM calculation for comparison purpose. Two kinds of input sets are utilized for response surface method to investigate and compare the effects of the uncertainty of input variables on the RCS peak pressure following a FLB. The first set is composed of six major plant operational parameters and the second set is composed of five major modelling parameters. It is found through the analysis of results that the uncertainties of modelling parameters have more influence on the RCS peak pressure than the uncertainties of plant operational parameters and that the extra margin of 9% of peak pressure is gained. And one of the assumptions of EM calculation, which is usually accepted as conservative is found to be erroneous, that is, the initial core inlet temperature is found to act negatively on the RCS pressure following a FLB.

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