• 제목/요약/키워드: Gram-Schmidt orthogonal

검색결과 22건 처리시간 0.023초

Gram-Schmidt 직교화를 이용한 다중 워터마킹 (Multiple Watermarking Using Gram-Schmidt Orthogonal Processing)

  • 오윤희;강현호;박지환
    • 정보처리학회논문지C
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    • 제8C권6호
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    • pp.703-710
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    • 2001
  • 본 논문에서는 영상의 저작권 보호를 위하여 하나의 컨텐츠에 복수개의 서로 다른 워터마크를 삽입하는 다중 워터마킹(multiple watermarking)에 대하여 고찰한다. 대역확산(spread spectrum)을 이용한 다중 워터마킹에서 워터마크 삽입시 사용되는 키 사이의 직교성(orthogonality)이 유지되어야 삽입된 워터마크의 정확한 추출이 가능하게 된다. 랜덤계열 사이의 직교성을 유지하기 위하여 Gram-schmidt 직교화를 이용하여 워터마크를 삽입하는 방식을 제안한다. 제안 방식은 삽입된 워터마크를 정확하게 추출할 수 있을 뿐 아니라, 가우시안 노이즈 추가, 히스토그램 평활화, 감마 보정, 샤프닝, 명도/대비조정 등의 다양한 공격에 대하여 강인함을 보인다.

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직교화 기법을 이용한 앙상블 경험적 모드 분해법의 고유 모드 함수와 모드 직교성 (Intrinsic Mode Function and its Orthogonality of the Ensemble Empirical Mode Decomposition Using Orthogonalization Method)

  • 손수덕;하준홍;비자야 P. 포크렐;이승재
    • 한국공간구조학회논문집
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    • 제19권2호
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    • pp.101-108
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    • 2019
  • In this paper, the characteristic of intrinsic mode function(IMF) and its orthogonalization of ensemble empirical mode decomposition(EEMD), which is often used in the analysis of the non-linear or non-stationary signal, has been studied. In the decomposition process, the orthogonal IMF of EEMD was obtained by applying the Gram-Schmidt(G-S) orthogonalization method, and was compared with the IMF of orthogonal EMD(OEMD). Two signals for comparison analysis are adopted as the analytical test function and El Centro seismic wave. These target signals were compared by calculating the index of orthogonality(IO) and the spectral energy of the IMF. As a result of the analysis, an IMF with a high IO was obtained by GSO method, and the orthogonal EEMD using white noise was decomposed into orthogonal IMF with energy closer to the original signal than conventional OEMD.

직교 투사를 이용한 최적 레이다 신호 검출기 (An Optimum Radar Signal Detector using Orthogonal Projection)

  • 김영훈;김기만;이종길;박영찬;곽영길;윤대희
    • 한국통신학회논문지
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    • 제19권7호
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    • pp.1407-1413
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    • 1994
  • 레이다에서 정확한 표적 정보를 얻기 위해서는 우선 클러터나 간섭 신호를 효율적으로 제거하고 표적을 검출하여야 한다. 본 논문에서는 신호를 제한 조건에 의해 구별되는 직교 부공간으로 투사함으로써 최분산 기분을 갖는 최적 검출기를 제한 조건을 갖지 않는 검출기로 변형하였다. 제안된 방법은 기존의 최적검출 알고리듬과 등가이며, 역행렬을 구하지 않고서도 빠른 수렴속도를 얻기위한 Gram-Schmidt 적교화가 가능한 구조를 가지게 된다. 모의 실험을 통해 제안된 검출기가 공간과 주파수 영역에서 적응적으로 잘 동작하고 있음을 보였다.

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미지의 선형 시스템에 대한 실시감 회귀 모델링 (Real-time recursive identification of unknown linear systems)

  • 최수일;김병국
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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    • pp.548-553
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    • 1992
  • In this paper and recursive version of orthogonal ARMA identification algorithm is proposed. The basic algorithm is based on Gram-Schmidt orthogonalization of automatically selected basis functions from specified function space, but does not require explicit creation of orthogonal functions. By using two dimensional autocorrelations and crosscorrelations of input and output with constant data length, identification algorithm is extended to cope slowly time-varying or order-varying delayed system.

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MMSE based Wiener-Hopf Equation

  • Cho, Juphil;Lee, Il Kyu;Cha, Jae Sang
    • International Journal of Internet, Broadcasting and Communication
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    • 제4권1호
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    • pp.18-22
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    • 2012
  • In this paper, we propose an equivalent Wiener-Hopf equation. The proposed algorithm can obtain the weight vector of a TDL(tapped-delay-line) filter and the error simultaneously if the inputs are orthogonal to each other. The equivalent Wiener-Hopf equation was analyzed theoretically based on the MMSE(minimum mean square error) method. The results present that the proposed algorithm is equivalent to original Wiener-Hopf equation. In conclusion, our method can find the coefficient of the TDL (tapped-delay-line) filter where a lattice filter is used, and also when the process of Gram-Schmidt orthogonalization is used. Furthermore, a new cost function is suggested which may facilitate research in the adaptive signal processing area.

On the Design of Orthogonal Pulse-Shape Modulation for UWB Systems Using Hermite Pulses

  • Giuseppe, Thadeu Freitas de Abreu;Mitchell, Craig-John;Kohno, Ryuji
    • Journal of Communications and Networks
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    • 제5권4호
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    • pp.328-343
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    • 2003
  • Orthogonal pulse-shape modulation using Hermite pulses for ultra-wideband communications is reviewed. Closedform expressions of cross-correlations among Hermite pulses and their corresponding transmit and receive waveforms are provided. These show that the pulses lose orthogonality at the receiver in the presence of differentiating antennas. Using these expressions, an algebraic model is established based on the projections of distorted receive waveforms onto the orthonormal basis given by the set of normalized orthogonal Hermite pulses. Using this new matrix model, a number of pulse-shape modulation schemes are analyzed and a novel orthogonal design is proposed. In the proposed orthogonal design, transmit waveforms are constructed as combinations of elementary Hermites with weighting coefficients derived by employing the Gram-Schmidt (QR) factorization of the differentiating distortion model’s matrix. The design ensures orthogonality of the vectors at the output of the receiver bank of correlators, without requiring compensation for the distortion introduced by the antennas. In addition, a new set of elementary Hermite Pulses is proposed which further enhances the performance of the new design while enabling a simplified hardware implementation.

THE EXISTENCE THEOREM OF ORTHOGONAL MATRICES WITH p NONZERO ENTRIES

  • CHEON, GI-SANG;LEE, SANG-GU;SONG, SEOK-ZUN
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • 제4권1호
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    • pp.109-119
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    • 2000
  • It was shown that if Q is a fully indecomposable $n{\times}n$ orthogonal matrix then Q has at least 4n-4 nonzero entries in 1993. In this paper, we show that for each integer p with $4n-4{\leq}p{\leq}n^2$, there exist a fully indecomposable $n{\times}n$ orthogonal matrix with exactly p nonzero entries. Furthermore, we obtain a method of construction of a fully indecomposable $n{\times}n$ orthogonal matrix which has exactly 4n-4 nonzero entries. This is a part of the study in sparse matrices.

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탄성체 경계 트랙션을 구하는 문제에서 상호 수직 기저 함수를 사용한 역문제 해석 방법의 개발 (Development of an Inverse Method Using Orthogonal Basis Functions for the Evaluation of Boundary Tractions on an Elastic Body)

  • 김사영;김현규
    • 대한기계학회논문집A
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    • 제34권4호
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    • pp.487-493
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    • 2010
  • 대부분의 구조해석 문제는 외부에서 주어진 하중에 대한 변형과 응력에 관심을 두고 있지만 많은 경우에서 표면 또는 내부에 주어진 응력이나 트랙션을 구하는 역문제 해석이 필요하게 된다. 본 연구에서는 구하고자 하는 트랙션에서 멀리 떨어진 영역의 변위를 측정하여 미지의 트랙션을 평가하는데 유한요소법을 사용한 역문제 수식화를 적용하였다. 일반적으로 역시스템의 불안정으로 인하여 측정 변위의 작은 오차는 해석 결과에 큰 영향을 주게 된다. 이와 같은 역시스템의 불안정성을 개선하기 위하여 본 연구에서는 구하고자 하는 트랙션에 가까운 단면의 변위를 Gram-Schmidt 수직화 기법을 통한 수직기저함수 사용하여 예측하고 보다 안정된 역문제를 해석하는 방법을 개발하였고 장점들을 수치 예제를 통하여 보여주었다.

Codebook-Based Precoding for SDMA-OFDMA with Spectrum Sharing

  • Jo, Han-Shin
    • ETRI Journal
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    • 제33권6호
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    • pp.831-840
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    • 2011
  • This paper focuses on codebook-based precoding for space-division multiple access/orthogonal frequency-division multiple access (SDMA-OFDMA) systems aiming to guarantee high throughput for their users as well as to mitigate interference to fixed satellite service (FSS). A systematic design of SDMA codebook for subband-based OFDMA is proposed, which forms multiple orthogonal beams with common spatial null in the direction of a victim FSS earth station (ES). The design enables both transmitter and receiver to independently construct identical codebook by sharing only on the direction angle of an FSS ES, which takes fewer overhead bits than Gram-Schmidt process, a general method satisfying our design criterion. A system-level throughput evaluation shows that the proposed precoding provides superior performance over existing spectrum sharing method, that is, subband deactivation. The spectrum sharing analysis shows that the proposed precoding, even with an estimation error of the direction angles of an FSS ES, causes lower interference than existing precoding, knockdown precoding.

미지의 선형 MIMO 시스템에 대한 On-Line 모델링 알고리즘 (On-Line Identification Algorithm for Unknown Linear MIMO Systems)

  • 최수일;김병국
    • 전자공학회논문지B
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    • 제31B권7호
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    • pp.58-65
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    • 1994
  • A recursive on-line algorithm for orthogonal ARMA identification is proposed for linear MIMO systems with unknown parameters time delay and order. This algorithm is based on the Gram-Schmidt orthogonalization of basis functions, and extended to a recursiveform by using new functions of two dimensional autocorrelations and crosscorrelations of inputs and outputs. This proposed algorithm can also cope with slowly time-varying or order-varying systems. Various simulations reveal the performance of the algorithm.

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