• Title/Summary/Keyword: proper orthogonal decomposition

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Linearized Modeling Technique for Complex Dynamic Responses Using Proper Orthogonal Decomposition (적합직교분해법을 이용한 복잡한 동적응답의 선형화 모델링 기법)

  • Lee, Soo-Il;Hong, Sang-Hyuk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.156-159
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    • 2008
  • Proper orthogonal decomposition is a statistical pattern analysis technique for finding the dominant components, called the proper orthogonal modes, in ensembles of spatially distributed data. We present recent ideas based on proper orthogonal decomposition (POD) and detailed experiments that yield new perspectives into the microscale structures. The linearized modeling technique based on POD is very useful to show the principal characteristics of the complex dynamic responses.

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A Study on Aerodynamic Reduced Order Model Using Proper Orthogonal Decomposition (Proper Orthogonal Decomposition을 이용한 공력축소모델 연구)

  • Jun, Sang-Ook;Park, Kyung-Hyun;Kang, Seung-On;Lee, Dong-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2009.04a
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    • pp.151-154
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    • 2009
  • 본 연구에서는 Proper Orthogonal Decomposition (POD)를 이용하여 공력축소모델을 구축하였다. 일반적으로 Euler equations과 같은 높은 정확도를 가지는 공력해석을 수행할 경우 많은 계산 비용이 발생하게 된다. 특히 공탄성 해석과 같이 수차례의 공력해석이 필요한 경우 그 비용은 더 증가하게 된다. 이러한 문제를 줄이기 위해서 축소모델(Reduced Order Model; ROM)의 개발은 반드시 필요하다. 공력축소모델을 구하는 방법 중 하나인 POD는 snapshot 데이터로부터 기저벡터를 구하고, 이들의 선형결합을 통하여 축소된 공간에서 해를 찾는 방법이다. 본 연구에서는 POD 기저벡터를 이용한 공력축소모델을 구축하고, 이를 전투기 날개문제에 적용하여 구하여진 정상상태 해와 Euler 해석 결과를 비교해 보았다. 또한 진동하는 익형문제에 적용하여 봄으로써 공탄성 해석에 적용 가능성 여부를 확인하였다.

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Modal Identification of a Slender Structure using the Proper Orthogonal Decomposition Method (Proper Orthogonal Decomposition 기법을 이용한 세장한 구조물의 모드인자 파악)

  • Ham, Hee-Jung
    • Journal of Industrial Technology
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    • v.28 no.B
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    • pp.135-141
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    • 2008
  • In this paper, the Proper Orthogonal Decomposition (POD) method, which is a statistical analysis technique to find the modal characteristics of a structure, is adapted to identify the modal parameters of a tall chimney structure. A wind force time history, which is applied to the structure, is obtained by a wind tunnel test of a scale down model. The POD method is applied on the wind force induced responses of the structure, and the true normal modes of the structure can be obtained. The modal parameters including, natural frequency, mode shape, damping ratio and kinetic energy of the structure can be estimated accurately. With these results, it may be concluded that the POD method can be applied to obtain accurate modal parameters from the wind-induced building responses.

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Understanding of the High-speed Flame Movement of Gas Turbine Combustion Instability using a Proper Orthogonal Decomposition Method (정규직교분해법을 이용한 가스터빈 연소불안정 고속 화염거동의 이해)

  • Yoon, Seokhyun;Park, Hyemi;Lee, Min Chul
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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    • pp.117-119
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    • 2015
  • This paper presents the methods and examples of proper orthogonal decomposition analysis for the understanding of high speed flame movements induced by combustion instabilities in a gas turbine. Phase resolved high-speed flame images were obtained from the combustion test of an industrial gas turbine at the rate of 2000 frame per second, and were utilized for the proper orthogonal decomposition. This analyzing method provided useful information regarding combustion instability characteristics bringing alleviation idea of the instabilities, such as principle modes of flame movement and their energy fractions which mean by which modes and how much the flame coherent structures are composed.

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Understanding of unsteady pressure fields on prisms based on covariance and spectral proper orthogonal decompositions

  • Hoa, Le Thai;Tamura, Yukio;Matsumoto, Masaru;Shirato, Hiromichi
    • Wind and Structures
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    • v.16 no.5
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    • pp.517-540
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    • 2013
  • This paper presents applications of proper orthogonal decomposition in both the time and frequency domains based on both cross spectral matrix and covariance matrix branches to analyze multi-variate unsteady pressure fields on prisms and to study spanwise and chordwise pressure distribution. Furthermore, modification of proper orthogonal decomposition is applied to a rectangular spanwise coherence matrix in order to investigate the spanwise correlation and coherence of the unsteady pressure fields. The unsteady pressure fields have been directly measured in wind tunnel tests on some typical prisms with slenderness ratios B/D=1, B/D=1 with a splitter plate in the wake, and B/D=5. Significance and contribution of the first covariance mode associated with the first principal coordinates as well as those of the first spectral eigenvalue and associated spectral mode are clarified by synthesis of the unsteady pressure fields and identification of intrinsic events inside the unsteady pressure fields. Spanwise coherence of the unsteady pressure fields has been mapped the first time ever for better understanding of their intrinsic characteristics.

Modal Analysis of the Tapping AFM Microcantilevers Using Proper Orthogonal Decomposition (적합직교분해법을 이용한 AFM 마이크로캔틸레버의 모드해석)

  • Hong, Sang-Hyuk;Cho, Hong-Mo;Lee, Soo-Il
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1773-1777
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    • 2008
  • The proper orthogonal decomposition(POD) is used to the modal analysis of microcantilever of dynamic mode atomic force microscopy(AFM). The proper orthogonal modes(POM) are extracted from vibrating signals of microcantilever when it resonates and taps the sample. We present recent ideas based on POD and detailed experiments that yield new perspectives into the microscale structures. The linearized modeling technique based on POD is very useful to show the principal characteristics of the complex dynamic responses.

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Vibration Analysis of the Tapping AFM Microcantilevers Using Proper Orthogonal Decomposition (적합직교분해법을 이용한 AFM 마이크로캔틸레버의 진동해석)

  • Hong, Sang-Hyuk;Lee, Soo-Il
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.4
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    • pp.414-421
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    • 2010
  • The proper orthogonal decomposition(POD) is used to the vibration analysis of microcantilever in tapping mode atomic force microscopy(AFM). The proper orthogonal modes (POM) are extracted from vibrating signals of microcantilever when it resonates and taps the sample. We present recent ideas based on POD and detailed experiments that yield new perspectives into the microscale structures such as the tapping cantilever. The linearized modeling technique based on POD is very useful to show the principal characteristics of the complex dynamic responses of the AFM microcantilever.

Extraction of the mode shapes of a segmented ship model with a hydroelastic response

  • Kim, Yooil;Ahn, In-Gyu;Park, Sung-Gun
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.6
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    • pp.979-994
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    • 2015
  • The mode shapes of a segmented hull model towed in a model basin were predicted using both the Proper Orthogonal Decomposition (POD) and cross random decrement technique. The proper orthogonal decomposition, which is also known as Karhunen-Loeve decomposition, is an emerging technology as a useful signal processing technique in structural dynamics. The technique is based on the fact that the eigenvectors of a spatial coherence matrix become the mode shapes of the system under free and randomly excited forced vibration conditions. Taking advantage of the simplicity of POD, efforts have been made to reveal the mode shapes of vibrating flexible hull under random wave excitation. First, the segmented hull model of a 400 K ore carrier with 3 flexible connections was towed in a model basin under different sea states and the time histories of the vertical bending moment at three different locations were measured. The measured response time histories were processed using the proper orthogonal decomposition, eventually to obtain both the first and second vertical vibration modes of the flexible hull. A comparison of the obtained mode shapes with those obtained using the cross random decrement technique showed excellent correspondence between the two results.

Proper Orthogonal Mode Analysis of AFM Microcantilevers in Dynamic Mode (동적모드 AFM 마이크로캔틸레버의 적합직교모드 해석)

  • Cho, Hong-Mo;Lee, Soo-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.606-611
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    • 2007
  • Proper orthogonal decomposition (POD) is a method for extracting bases for modal decomposition from the ensemble of dynamic signals. Using the POD method, we analyzed the proper orthogonal modes (POMs) of AFM microcantilevers in dynamic mode operations such as Tapping Mode. The POMs and POVs (proper orthogonal values) were computed through MATLAB simulation for the 5-mode model of the microcantilever. We found that the POV portion of the higher POMs of the tapping microcanilever slightly increased in comparison with no tapping. This implies that the modal energy in the fundamental mode can be transferred to the higher modes during tapping.

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Multi-disciplinary Optimization of Composite Sandwich Structure for an Aircraft Wing Skin Using Proper Orthogonal Decomposition (적합직교분해법을 이용한 항공기 날개 스킨 복합재 샌드위치 구조의 다분야 최적화)

  • Park, Chanwoo;Kim, Young Sang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.7
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    • pp.535-540
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    • 2019
  • The coupling between different models for MDO (Multi-disciplinary Optimization) greatly increases the complexity of the computational framework, while at the same time increasing CPU time and memory usage. To overcome these difficulties, POD (Proper Orthogonal Decomposition) and RBF (Radial Basis Function) are used to solve the optimization problem of determining the thickness of composites and sandwich cores when composite sandwich structures are used as aircraft wing skin materials. POD and RBF are used to construct surrogate models for the wing shape and the load data. Optimization is performed using the objective function and constraint function values which are obtained from the surrogate models.