• 제목/요약/키워드: Frequency-weighted

검색결과 473건 처리시간 0.023초

A Low Frequency Band Watermarking with Weighted Correction in the Combined Cosine and Wavelet Transform Domain

  • Deb, Kaushik;Al-Seraj, Md. Sajib;Chong, Ui-Pil
    • 융합신호처리학회논문지
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    • 제14권1호
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    • pp.13-20
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    • 2013
  • A combined DWT and DCT based watermarking technique of low frequency watermarking with weighted correction is proposed. The DWT has excellent spatial localization, frequency spread and multi-resolution characteristics, which are similar to the theoretical models of the human visual system (HVS). The DCT based watermarking techniques offer compression while DWT based watermarking techniques offer scalability. These desirable properties are used in this combined watermarking technique. In the proposed method watermark bits are embedded in the low frequency band of each DCT block of selected DWT sub-band. The weighted correction is also used to improve the imperceptibility. The extracting procedure reverses the embedding operations without the reference of the original image. Compared with the similar approach by DCT based approach and DWT based approach, the experimental results show that the proposed algorithm apparently preserves superiori mage quality and robustness under various attacks such as JPEG compression, cropping, sharping, contrast adjustments and so on.

가중된 직교 선형 FM신호를 이용한 송신 동시 다중 빔집속 기반의 초음파 영상 기법 (Simultaneous Multiple Transmit Focusing Using Orthogonal Weighted Linear FM Chirp)

  • 정영관;송태경
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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    • pp.155-158
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    • 2001
  • A new method for simultaneous multiple transmit focusing using orthogonal weighted FM chirp is proposed. Weighted chirp signals focused at different depths are transmitted at the same time. These chirp signals are mutually orthogonal in the approximate sense that the autocorrelation function of each signal has a narrow mainlobe width and low sidelobe levels, and the crosscorrellation function of any pair of the signals has smaller values than the sidelobe levels of each autocorrelation function. This means that each weighted chirp signal can be separately compressed into a short pulse, focused individually and combined with other focused beams to form a frame of image. Theoretically, any two chirp signals defined in two nonoverlapped frequency bands are mutually orthogonal. In the present work, however, a fractional overlap of adjacent frequency bands, by up to 25%, were permitted to design more chirp signals within a given transducer bandwidth. The crosscorrelation values due to the frequency overlap could be reduced by alternating the direction of frequency sweep of the adjacent chirp signals. The simulation results show that this method can improve the lateral resolution of image without sacrifice in the frame rate compared with the conventional pulse system.

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식이섭취조사방법과 조사일수에 따른 한국 젊은 여성의 영양소 섭취 수준의 비교 (Comparison of the Levels of Nutrient Intakes by Different Dietary Methods and Days of Dietary Studies Among Young Females in Korea)

  • 오세영
    • Journal of Nutrition and Health
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    • 제29권9호
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    • pp.1021-1027
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    • 1996
  • This study examined the patterns of nutrient intakes measured by 1-, 3-, 7-day recalls and records as well as food frequency questionnaire among 59 females volunteers enrolled in the university in Seoul, Korea. Over a 4 month period, a modified Willett food frequency questionnaire was administered once, and a 24-hour dietary recall was conducted 12 times and a weighted dietary record 14 times. From these 12 recalls and 14 records, 1-, 3-, 7-day data were randomly selected. For energy and 11 nutrients, group mean intakes derived from food frequency questionnaire were higher than from recalls and records. Group mean intakes from recalls and records showed little differences depending on days of dietary studies and dietary methods. Measures of agreement were calculated by weighted kappa and intraclass correlation coefficient values calculated for quintile categories while comparing to the results of 26 days recalls and records. Weighted kappa values ranged from 0.11 for riboflavin to 0.36 for vitamin C for and 1-day recall, and from 0.21 for iron to 0.31 for energy for the 1-day record. Weighted kappa values were increased as the number of days of dietary studies increased (0.34-0.57 for the 3-day recalls, 0.27-0.50 for the 3-day records, 0.50-0.68 for the 7-day recalls, and 0.50-0.65 for the 7-day records). Weighted kappa values for food frequency questionnaire were higher than the 1-day data, but lower than the 3-and-7day data(0.34 for energy, 0.31 for iron and 0.22 for vitamin C). Intraclass correlation coefficients ranged from 0.21 for vitamin A to 0.57 for calcium. The degrees of agreement by different methods and days of dietary study are lower in our study compared to agreement by different methods and days of dietary study are lower in our study compared to those in previously published studies for Western populations, partly due to the differences of data analysis methods as well as of dietary patterns between those samples and ours.

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주파수 영역에서 통과대역 오차 감소를 갖는 모델 저차수화 (Model order reduction with pass band error reduction in frequency domain)

  • 김정화;정찬수
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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    • pp.1219-1219
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    • 1991
  • This paper proposes the model order reduction with pass band error reduction in the frequency domain of discrete time linear systems. The algorithm is the new method of reduced order model which reduces passband error by changing controllability and observability gramian used with weighted functions. A numerical example shows that this algorithm has lower passband error than balanced w&l and weighted function characteristics in frequency domain.

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Multi-Frame Super-Resolution of High Frequency with Spatially Weighted Bilateral Total Variance Regularization

  • Lee, Oh-Young;Park, Sae-Jin;Kim, Jae-Woo;Kim, Jong-Ok
    • IEIE Transactions on Smart Processing and Computing
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    • 제3권5호
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    • pp.271-274
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    • 2014
  • Bayesian based Multi-Frame Super-Resolution (MF-SR) has been used as a popular and effective SR model. On the other hand, the texture region is not reconstructed sufficiently because it works on the spatial domain. In this study, the MF-SR method was extended to operate on the frequency domain to improve HF information as much as possible. For this, a spatially weighted bilateral total variation model was proposed as a regularization term for a Bayesian estimation. The experimental results showed that the proposed method can recover the texture region more realistically with reduced noise, compared to conventional methods.

On Narrowband Interference Suppression in OFDM-based Systems with CDMA and Weighted-type Fractional Fourier Transform Domain Preprocessing

  • Liang, Yuan;Da, Xinyu;Wang, Shu
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제11권11호
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    • pp.5377-5391
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    • 2017
  • In this paper, we propose a new scheme to suppress the narrowband interference (NBI) in OFDM-based systems. The scheme utilizes code division multiple access (CDMA) and weighted-type fractional Fourier transform (WFRFT) domain preprocessing technologies. Through setting the WFRFT order, the scheme can switch into a single carrier (SC) or a multi-carrier (MC) frequency division multiple access block transmission system. The residual NBI can be eliminated to the maximum extent when the WFRFT order is selected properly. Final simulation results show that the proposed system can outperform MC and SC with CDMA and frequency domain preprocessing in terms of the narrowband interference suppression.

Frequency Control of in Hybrid Wind Power System using Flywheel Energy Storage System

  • Lee, Jeong-Phil;Kim, Han-Guen
    • Journal of international Conference on Electrical Machines and Systems
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    • 제3권2호
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    • pp.229-234
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    • 2014
  • In this paper, a design problem of the flywheel energy storage system controller using genetic algorithm (GA) is investigated for a frequency control of the wind diesel hybrid power generation system in an isolated power system. In order to select parameters of the FESS controller, two performance indexes are used. We evaluated a frequency control effect for the wind diesel hybrid power system according to change of the weighted values of a performance index. To verify performance of the FESS controller according to the weighted value of the performance index, the frequency domain analysis using a singular value bode diagram and the dynamic simulations for various weighted values of performance index were performed. To verify control performance of the designed FESS controller, the eigenvalue analysis and the dynamic simulations were performed. The control characteristics with the two designed FESS controller were compared with that of the conventional pitch controller. The simulation results showed that the FESS controller provided better dynamic responses in comparison with the conventional controller.

고빈도 금융 시계열 실현 변동성을 이용한 가중 융합 변동성의 가중치 선택 (Choice of weights in a hybrid volatility based on high-frequency realized volatility)

  • 윤재은;황선영
    • 응용통계연구
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    • 제29권3호
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    • pp.505-512
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    • 2016
  • 본 연구에서는 금융시계열의 일간 변동성 측정을 위해 가중 융합 방법을 제안하고 있다. 고빈도(high frequency)자료에 기반을 둔 조정된 실현변동성을 계산하고 이를 참 값으로 간주하여 제안된 가중 융합 변동성에서 최적 가중치를 결정하는 과정을 서술하였다. 국내 KOSPI200자료의 1분 단위 고빈도 주가로부터 조정된 실현변동성을 구한 후 최적의 가중 융합 변동성을 제안해 보았다.

평활화 된 의사거리 및 전리층 지연 추정을 위한 GPS 측정치 잡음 모델링 (Modeling of GPS measurement noise for estimating smoothed pseudorange and ionospheric delay)

  • 한덕화;윤호;기창돈
    • 한국항행학회논문지
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    • 제16권4호
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    • pp.602-610
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    • 2012
  • GPS 신호의 주요 오차 요인 중 전리층 지연 오차는 신호 주파수에 따라 지연량이 달라지는 특성을 가진다. 이중 주파수 사용자는 L1, L2 주파수의 의사거리 측정치의 차이 값을 이용하여 보정하게 되는데, 이렇게 추정된 전리층 지연 추정치에는 의사거리 잡음에 의한 오차가 포함되게 되므로 일반적으로 필터를 통해 의사거리 측정치를 평활화 시킨 후 전리층 지연을 계산하게 된다. Weighted hatch filter는 측정치의 잡음 수준을 고려하여 최적의 평활화 된 의사거리 측정치를 계산해 낼 수 있으나, 이를 이용하기 위해서는 측정치 잡음에 대한 모델링이 필요하다. 본 논문에서는 NDGPS 기준국들에 대하여 측정치 잡음 모델링을 수행하였다. 그리고 모델링 결과를 바탕으로 weighted hatch filter를 구성하여 평활화 된 의사거리 측정치 및 전리층 지연을 추정한 결과 필터를 적용하지 않은 것에 비하여 전리층 지연 오차의 표준편차가 1/25 가량으로 줄어드는 것을 확인하였다.

가중치 합을 이용한 웨이블릿 영역의 디모자이킹 (Demosaicking Using Weighted Sum in Wavelet domain)

  • 정보규;엄일규
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2008년도 하계종합학술대회
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    • pp.821-822
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    • 2008
  • This paper presents a new demosaicking method based on weighted sum in the wavelet domain. In our method, the missing wavelet coefficients in lowest frequency subband are obtained by weighted sum. Since detail coefficients have large values at the edge region, these values are used as weighting factors. Detail coefficients are replaced by the coefficients in the corresponding subbands. Experimental results show that the proposed method generates good performance.

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