• 제목/요약/키워드: Proper Orthogonal Decomposition (POD)

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

  • 이수일;홍상혁
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2008년도 춘계학술대회논문집
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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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Proper Orthogonal Decomposition 기법을 이용한 세장한 구조물의 모드인자 파악 (Modal Identification of a Slender Structure using the Proper Orthogonal Decomposition Method)

  • 함희정
    • 산업기술연구
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    • 제28권B호
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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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Proper Orthogonal Decomposition을 이용한 공력축소모델 연구 (A Study on Aerodynamic Reduced Order Model Using Proper Orthogonal Decomposition)

  • 전상욱;박경현;강승온;이동호
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2009년도 정기 학술대회
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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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Proper orthogonal decomposition in wind engineering - Part 1: A state-of-the-art and some prospects

  • Solari, Giovanni;Carassale, Luigi;Tubino, Federica
    • Wind and Structures
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    • 제10권2호
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    • pp.153-176
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    • 2007
  • The Proper Orthogonal Decomposition (POD) is a statistical method particularly suitable and versatile for dealing with many problems concerning wind engineering and several other scientific and humanist fields. POD represents a random process as a linear combination of deterministic functions, the POD modes, modulated by uncorrelated random coefficients, the principal components. It owes its popularity to the property that only few terms of the series are usually needed to capture the most energetic coherent structures of the process, and a link often exists between each dominant mode and the main mechanisms of the phenomenon. For this reason, POD modes are normally used to identify low-dimensional subspaces appropriate for the construction of reduced models. This paper provides a state-of-the-art and some prospects on POD, with special regard to its framework and applications in wind engineering. A wide bibliography is also reported.

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

  • 홍상혁;조홍모;이수일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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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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적합직교분해법을 이용한 AFM 마이크로캔틸레버의 진동해석 (Vibration Analysis of the Tapping AFM Microcantilevers Using Proper Orthogonal Decomposition)

  • 홍상혁;이수일
    • 한국소음진동공학회논문집
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    • 제20권4호
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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.

POD를 사용한 3차원 후향계단 유동장 분석 예제 (EXAMPLES OF REDUCED ORDER MODELLING FOR A 3D BACKWARD FACING STEP FLOW USING POD TECHNIQUE)

  • 이광섭;이은석
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2010년 춘계학술대회논문집
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    • pp.40-42
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    • 2010
  • Unsteady CFD results of the backward facing step (BFS) flow field is reconstructed by the low-dimenstional modes using the POD (Proper Orthogonal Decomposition) technique. Flow responses to the blowing or suction with various frequencies and amplitudes applied at the edge of the BFS can also be analysed using the same technique. The present technique can be effectively applied to the feedback flow control device.

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

  • 박찬우;김영상
    • 한국항공우주학회지
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    • 제47권7호
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    • pp.535-540
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    • 2019
  • MDO(Multi-disciplinary Optimization)를 위한 서로 다른 모델 간의 결합은 계산 프레임 워크의 복잡성을 크게 증가시키는 동시에 CPU 시간과 메모리 사용을 증가시킨다. 이러한 어려움을 극복하기 위해 POD(Proper Orthogonal Decomposition)와 RBF(Radial Basis Function)를 사용하여 복합 샌드위치 구조가 항공기 날개 스킨 재료로 사용될 때 복합재와 샌드위치 코어의 두께를 결정하는 최적화 문제의 해를 구했다. POD와 RBF를 사용하여 날개 형상과 하중 데이터에 대한 대리 모델을 만들었으며 대리 모델에 의해 얻어진 목적 함수 및 제약 함수 값을 사용하여 최적해를 구하였다.

Separation-hybrid models for simulating nonstationary stochastic turbulent wind fields

  • Long Yan;Zhangjun Liu;Xinxin Ruan;Bohang Xu
    • Wind and Structures
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    • 제38권1호
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    • pp.1-13
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    • 2024
  • In order to effectively simulate nonstationary stochastic turbulent wind fields, four separation hybrid (SEP-H) models are proposed in the present study. Based on the assumption that the lateral turbulence component at one single-point is uncorrelated with the longitudinal and vertical turbulence components, the fluctuating wind is separated into 2nV-1D and nV1D nonstationary stochastic vector processes. The first process can be expressed as double proper orthogonal decomposition (DPOD) or proper orthogonal decomposition and spectral representation method (POD-SRM), and the second process can be expressed as POD or SRM. On this basis, four SEP-H models of nonstationary stochastic turbulent wind fields are developed. In addition, the orthogonal random variables in the SEP-H models are presented as random orthogonal functions of elementary random variables. Meanwhile, the number theoretical method (NTM) is conveniently adopted to select representative points set of the elementary random variables. The POD-FFT (Fast Fourier transform) technique is introduced in frequency to give full play to the computational efficiency of the SEP-H models. Finally, taking a long-span bridge as the engineering background, the SEP-H models are compared with the dimension-reduction DPOD (DR-DPOD) model to verify the effectiveness and superiority of the proposed models.

고층 타워에 작용하는 동적 풍압력의 POD 방법을 이용한 시공간적 특성 해석 (Proper Orthogonal Decomposition Analysis of Dynamic Wind Pressures Acting on a Tall Tower Model)

  • 이미화;함희정
    • 산업기술연구
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    • 제24권B호
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    • pp.29-36
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    • 2004
  • The wind and wind-induced dynamic wind pressures fluctuate irregularly according to time and space. In this study, the proper orthogonal decomposition(POD) technique is applied to wind pressures acting on a tall tower model, and the following results are found: the along-wind and across-wind forces can be reconstructed by only four dominant POD modes, and the reconstructed errors are 4.71% and 22%, respectively for across-wind and along-wind directions. The physical meanings for dominant modes are also presented in the paper. The POD analysis can compress complex wind pressure data only by a few dominant modes and interpret spatio-temporal characteristics of wind pressure by novel way while existing statistical methods do not have such benefits.

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