• Title/Summary/Keyword: matrix domain

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An Implementation of Inverse Filter for Sound Reproduction of Non-Minimum Phase System. (비최소 위상 시스템에서 음재생을 위한 역변환 필터의 구현)

  • 노경래;이상권
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.997-1002
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    • 2001
  • This paper describes an implementation of inverse filter using SVD in order to recover the input in multi-channel system. The matrix formulation in SISO system is extended to MIMO system. In time and frequency domain we investigates the inversion of minimum phase system and non-minimum phase system. To execute an effective inversion of non-minimum phase system, SVD is introduced. First of all we computes singular values of system matrix and then investigates the phase property of system. In case of overall system is non-minimum phase, system matrix has one (or more) very small singular value(s). The very small singular value(s) carries information about phase properties of system. Using this property, approximate inverse filter of overall system is founded. The numerical simulation shows potentials in use of the inverse filter.

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Vibration Analysis of the Moving Plates Subjected to the Force of Gravity

  • Jooyong Cho;Kim, Doyeon;Lee, Usik
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.3-10
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    • 2003
  • The use of frequency-dependent dynamic stiffness matrix (or spectral element matrix) in structural dynamics may provide very accurate solutions, while it reduces the number of degrees-of-freedom to improve the computational efficiency and cost problems. Thus, this paper develops a spectral element model for the thin plates moving with constant speed under uniform in-plane tension and gravity. The concept of Kantorovich method and the principle of virtual displacement is used in the frequency-domain to formulate the dynamic stiffness matrix. The present spectral element model is evaluated by comparing its solutions with the exact analytical solutions. The effects of moving speed, in-plane tension and gravity on the natural frequencies of the plate are numerically investigated.

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Modal Analysis of One Dimensional Distributed Parameter Systems by Using the Digital Modeling Technique (디지털 모델링 기법에 의한 1차원 연속계의 모드 해석)

  • 홍성욱;조종환
    • Journal of KSNVE
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    • v.9 no.1
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    • pp.103-112
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    • 1999
  • A new modeling and analysis technique for one-dimensional distributed parameter systems is presented. First. discretized equations of motion in Laplace domain are derived by applying discretization methods for partial differential equations of a one-dimensional structure with respect to spatial coordinate. Secondly. the z and inverse z transformations are applied to the discretized equations of motion for obtaining a dynamic matrix for a uniform element. Four different discretization methods are tested with an example. Finally, taking infinite on the number of step for a uniform element leads to an exact dynamic matrix for the uniform element. A generalized modal analysis procedure for eigenvalue analysis and modal expansion is also presented. The resulting element dynamic matrix is tested with a numerical example. Another application example is provided to demonstrate the applicability of the proposed method.

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Low Pilot Ratio Channel Estimation for OFDM Systems Based on GCE-BEM

  • Wang, Lidong;Lim, Dong-Min
    • Journal of electromagnetic engineering and science
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    • v.7 no.4
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    • pp.195-200
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    • 2007
  • Doubly-selective channel estimator for orthogonal frequency division multiplexing(OFDM) systems is proposed in this paper. Based on the generalized complex exponential basis expansion model(GCE-BEM), we describe the time-variant channel with time-invariant coefficients over multiple OFDM blocks. The time variation of the channel destroys the orthogonality between subcarriers, and the resulting channel matrix in the frequency domain is no longer diagonal, but the main interference comes from the near subcarriers. Based on this, we propose a channel estimator with low pilot ratio. We first develop a least-square(LS) estimator under the assumption that only the maximum Doppler frequency and the channel order are known at the receiver, and then verify that the correlation matrix of inter-channel interference(ICI) is a scaled identity matrix based on which we derive an optimal pilot insertion scheme for the LS estimator in the sense of minimum mean square error. The proposed estimator has the advantages of low pilot ratio and robustness against inter-carrier interference.

Image Data Processing by Lee Weighted Hadamard Transform (이 웨이티드 아다마르 변환을 이용한 영상신호 처리에 관한 연구)

  • 이문호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.10 no.2
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    • pp.93-103
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    • 1985
  • The digital signal processing technique by bandwidth compression has been grown up ragidly owing to integrated circuit developments. In this project, we have proposed the Lee Weighted Hadamard (LWH) transform which retains the main properties of Hadamard matirx. The LWH matrix was weighted in the center of the spatial domain. The human visual of the mid spatial are emphasized more than the low and high spatial frequencies. The fast algorithms of the LWH transform has been studied for hardware realization. The result of this project are availabel to airplane photograph, X-Ray, CATV and the artificial satellite of the digital image processing.

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Model Updating Using the Closed-loop Natural Frequency (폐루프 공진 주파수를 이용한 모델 개선법)

  • Jung Hunsang;Park Youngjin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.9 s.90
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    • pp.801-810
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    • 2004
  • Parameter modification of a linear finite element model(FEM) based on modal sensitivity matrix is usually performed through an effort to match FEM modal data to experimental ones. However, there are cases where this method can't be applied successfully; lack of reliable modal data and ill-conditioning of the modal sensitivity matrix constitute such cases. In this research, a novel concept of introducing feedback loops to the conventional modal test setup is proposed. This method uses closed-loop natural frequency data for parameter modification to overcome the problems associated with the conventional method based on modal sensitivity matrix. We proposed the whole procedure of parameter modification using the closed-loop natural frequency data including the modal sensitivity modification and controller design method. Proposed controller design method is efficient in changing modes. Numerical simulation of parameter estimation based on time-domain input/output data is provided to demonstrate the estimation performance of the proposed method.

Viscoelastic Analysis of Stress Intensity Factor for Interface Edge Crack in a Unidirectional Liminate (단일방향 복합재료의 공유면에 존재하는 계면 모서리균열의 점탄성 해석)

  • 이상순;김범식
    • Computational Structural Engineering
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    • v.10 no.1
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    • pp.129-134
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    • 1997
  • Interfacial stress singularity in a unidirectional two-dimensional laminate model consisting of an elastic fiber and a viscoelastic matrix has been investigated using the time-domain boundary element method. First, the interfacial singular stresses between the fiber and the matrix of a unidirectional laminate subjected to a uniform transverse tensile strain have been investigated near the free surface, but without any defect or any edge crack. Such a stress singularity might lead to fiber-matrix debonding or interfacial edge cracks. Then, the overall stress intensity factor for the case of a small interfacial edge crack of length a has been computed.

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Spectral Element Analysis of the Vibrations of Moving Plates Subjected to Axial Tension (장력을 받는 이동 평판이 갖는 진동의 스펙트럴 요소해석)

  • 조주용;김주홍;이우식;박상덕
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.192-199
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    • 2002
  • The use of frequency-dependent dynamic stiffness matrix (or spectral element matrix) in structural dynamics may provide very accurate solutions, while it reduces the number of degrees-of-freedom to improve the computational efficiency and cost problems. Thus, this paper develops a spectral element model for the thin plates moving with constant speed under uniform in-plane tension. The concept of Kantorovich method is used in the frequency-domain to formulate the dynamic stiffness matrix. The present spectral element model is evaluated by comparing its solutions with the exact analytical solutions. The effects of moving speed and in-plane tension on the flexural wave dispersion characteristics and natural frequencies of the plate are numerically investigated.

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Wave propagation in unbounded elastic domains using the spectral element method: formulation

  • Meza Fajardo, Kristel C.;Papageorgiou, Apostolos S.
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.383-411
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    • 2012
  • The objective of the present paper is to review and implement the most recent developments in the Spectral Element Method (SEM), as well as improve aspects of its implementation in the study of wave propagation by numerical simulation in elastic unbounded domains. The classical formulation of the method is reviewed, and the construction of the mass matrix, stiffness matrix and the external force vector is expressed in terms of matrix operations that are familiar to earthquake engineers. To account for the radiation condition at the external boundaries of the domain, a new absorbing boundary condition, based on the Perfectly Matched Layer (PML) is proposed and implemented. The new formulation, referred to as the Multi-Axial Perfectly Matched Layer (M-PML), results from generalizing the classical Perfectly Matched Layer to a medium in which damping profiles are specified in more than one direction.

Casein kinase 2 promotes the TGF-β-induced activation of α-tubulin acetyltransferase 1 in fibroblasts cultured on a soft matrix

  • You, Eunae;Jeong, Jangho;Lee, Jieun;Keum, Seula;Hwang, Ye Eun;Choi, Jee-Hye;Rhee, Sangmyung
    • BMB Reports
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    • v.55 no.4
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    • pp.192-197
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    • 2022
  • Cell signals for growth factors depend on the mechanical properties of the extracellular matrix (ECM) surrounding the cells. Microtubule acetylation is involved in the transforming growth factor (TGF)-β-induced myofibroblast differentiation in the soft ECM. However, the mechanism of activation of α-tubulin acetyltransferase 1 (α-TAT1), a major α-tubulin acetyltransferase, in the soft ECM is not well defined. Here, we found that casein kinase 2 (CK2) is required for the TGF-β-induced activation of α-TAT1 that promotes microtubule acetylation in the soft matrix. Genetic mutation and pharmacological inhibition of CK2 catalytic activity specifically reduced microtubule acetylation in the cells cultured on a soft matrix rather than those cultured on a stiff matrix. Immunoprecipitation analysis showed that CK2α, a catalytic subunit of CK2, directly bound to the C-terminal domain of α-TAT1, and this interaction was more prominent in the cells cultured on the soft matrix. Moreover, the substitution of alanine with serine, the 236th amino acid located at the C-terminus, which contains the CK2-binding site of α-TAT1, significantly abrogated the TGF-β-induced microtubule acetylation in the soft matrix, indicating that the successful binding of CK2 and the C-terminus of α-TAT1 led to the phosphorylation of serine at the 236th position of amino acids in α-TAT1 and regulation of its catalytic activity. Taken together, our findings provide novel insights into the molecular mechanisms underlying the TGF-β-induced activation of α-TAT1 in a soft matrix.