• Title, Summary, Keyword: 주파수 응답

Search Result 1,346, Processing Time 0.045 seconds

Design Sensitivity Analysis of Frequency Response Using Krylov Subspace Based Model Reduction (Krylov 부공간 축소기법을 이용한 주파수응답의 설계민감도 해석)

  • Han, Jeong-Sam
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.131-134
    • /
    • 2009
  • Krylov 부공간 모델차수축소법은 초기 유한요소모델과 축소모델의 전달함수의 계수인 모멘트를 일치시키는 방법을 이용하는 축소기법으로 이미 대형 유한요소모델의 주파수응답 해석의 효율적인 계산에 많이 사용되고 있는 방법 중의 하나이다. 본 논문에서는 Krylov 부공간 축소기법을 이용한 관심 주파수영역에 대한 주파수응답 해석 및 이를 통하여 계산된 주파수응답의 여러 가지 설계변수에 대한 설계민감도 해석방법을 제안하였다. 일반적으로 구조물의 주파수응답을 고려한 최적설계를 위해서는 설계변수에 대한 관심 주파수영역에서의 주파수응답 및 그의 민감도 정보가 요구되므로, 고려하는 유한요소모델이 대형일 경우에 관심 주파수영역에서의 반복적인 해석으로 인한 계산비용의 문제가 대두된다. 본 논문에서는 축소모델을 이용하여 주파수응답과 주파수응답의 설계민감도 해석을 수행하여 계산의 효율성을 극대화하였다. 민감도 계산에는 시간측면과 구현의 용이성 측면에서 장점이 있는 준해석적 방법을 이용하였다. 수치 예제를 통하여 축소기법을 이용한 주파수응답의 설계민감도 해석 결과를 유한차분법에 근거한 민감도 결과와 비교하였다. 본 논문에서 제안된 방법을 이용하는 경우, 주파수응답을 고려한 최적설계를 계산비용 측면에서 매우 효율적으로 수행할 수 있을 것이다.

  • PDF

Fast Graphic Visualization of Frequency Response for Audio Equalizer (오디오 이퀄라이저를 위한 주파수 응답의 고속 그래픽 표현 방법)

  • Kim, Ki-Jun;Park, Hochong
    • Journal of Broadcast Engineering
    • /
    • v.20 no.4
    • /
    • pp.632-640
    • /
    • 2015
  • This paper proposes a new method for fast graphic visualization of accurate frequency response of audio equalizer (EQ). When a logarithmic frequency scale is used, a frequency response in high resolution is required for accurate low-band frequency response. However, the high-resolution frequency response requires a huge amount of computational load, which makes the real-time graphic visualization of frequency response impossible. In order to solve the problem of computational load, the proposed method utilizes a low-resolution virtual frequency response in the mid band. It first computes the virtual frequency response of each filter of EQ in the mid band, and then moves it to the target band so that the result corresponds to the desired filter response. Then, it determines the final frequency response of EQ by combining all filter responses. The experiments confirm that the proposed method provides the frequency response of EQ which has an equivalent shape to that computed in high frequency resolution with huge computational load.

The Measurement Algorithm for Microphone's Frequency Character Response Using OATSP (OATSP를 이용한 마이크로폰의 주파수 특성 응답 측정 알고리즘)

  • Park, Byoung-Uk;Kim, Hack-Yoon
    • The Journal of the Acoustical Society of Korea
    • /
    • v.26 no.2
    • /
    • pp.61-68
    • /
    • 2007
  • The frequency response of a microphone, which indicates the frequency range that a microphone can output within the approved level, is one of the most significant standards used to measure the characteristics of a microphone. At present, conventional methods of measuring the frequency response are complicated and involve the use of expensive equipment. To complement the disadvantages, this paper suggests a new algorithm that can measure the frequency response of a microphone in a simple manner. The algorithm suggested in this paper generates the Optimized Aoshima's Time Stretched Pulse(OATSP) signal from a computer via a standard speaker and measures the impulse response of a microphone by convolution the inverse OATSP signal and the received by the microphone to be measured. Then, the frequency response of the microphone to be measured is calculated using the signals. The performance test for the algorithm suggested in the study was conducted through a comparative analysis of the frequency response data and the measures of frequency response of the microphone measured by the algorithm. It proved that the algorithm is suitable for measuring the frequency response of a microphone, and that despite a few errors they are all within the error tolerance.

Improved Structural Identification Method in Frequency Domain (구조물의 동특성추정을 위한 개선된 주파수영역 기법)

  • Hong, Kyu Seon;Yun, Chung Bang
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.13 no.2
    • /
    • pp.1-10
    • /
    • 1993
  • Frequency response functions(FRF) are the most fundamental data for the frequency domain identifications of structural systems. In this paper, an improved method for estimating FRF's is presented. The new FRF estimator takes the weighted average of two conventional estimators, $H_1$(f) and $H_2$(f), utilizing the fact that $H_2$(f) gives more accurate estimate at resonance, while $H_1$(f) yields better results at antiresonances. Based on the estimated FRF's, the modal parameters of the structures, such as, natural frequencies, damping ratios and mode shapes, are also estimated. The effectiveness of the proposed method is investigated through numerical and experimental studies. The estimated results indicate that the proposed estimator gives more accurate results than other estimators.

  • PDF

Direct Design Sensitivity Analysis of Frequency Response Function Using Krylov Subspace Based Model Order Reduction (Krylov 부공간 모델차수축소법을 이용한 주파수응답함수의 직접 설계민감도 해석)

  • Han, Jeong-Sam
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.23 no.2
    • /
    • pp.153-163
    • /
    • 2010
  • In this paper a frequency response analysis using Krylov subspace-based model reduction and its design sensitivity analysis with respect to design variables are presented. Since the frequency response and its design sensitivity information are necessary for a gradient-based optimization, problems of high computational cost and resource may occur in the case that frequency response of a large sized finite element model is involved in the optimization iterations. In the suggested method model order reduction of finite element models are used to calculate both frequency response and frequency response sensitivity, therefore one can maximize the speed of numerical computation for the frequency response and its design sensitivity. As numerical examples, a semi-monocoque shell and an array-type $4{\times}4$ MEMS resonator are adopted to show the accuracy and efficiency of the suggested approach in calculating the FRF and its design sensitivity. The frequency response sensitivity through the model reduction shows a great time reduction in numerical computation and a good agreement with that from the initial full finite element model.

Multiple Audio Watermarking using Quantization Index Modulation on Frequency Phase and Magnitude Response (주파수 위상 응답과 크기 응답에 QIM을 이용한 다중 오디오 워터마킹)

  • Seo, Yejin;Cho, Sangjin;Chong, Uipil
    • The Journal of the Acoustical Society of Korea
    • /
    • v.32 no.1
    • /
    • pp.71-78
    • /
    • 2013
  • This paper describes a multiple audio watermarking using Quantization Index Modulation (QIM) on frequency phase and magnitude response. Proposed embedding procedure is composed of two stage. At the first stage, the watermark is embedded on the frequency phase response using QIM. In the second stage, the watermark is embedded using adaptive QIM with the step-size that is adaptively determined using the maximum value of the frequency magnitude response of every frame. The watermark is extracted by calculating the Euclidean distance as the blind detection. The proposed method is robust against most of attacks of audio watermark benchmarking. For the Fourier attacks, the proposed method shows over 95% recovery rate.

Nonproportional viscous damping matrix identification using frequency response functions (주파수 응답 데이터를 이용한 비비례 점성감쇠행렬 추정)

  • Min, Cheon-Hong;Kim, Hyung-Woo
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.40 no.4
    • /
    • pp.369-373
    • /
    • 2016
  • Accurate identification of damping matrix in structures is very important for predicting vibration responses and estimating parameters or other characteristics affected by energy dissipation. In this paper, damping matrix identification method that use normal frequency response functions, which were estimated from complex frequency response functions, is proposed. The complex frequency response functions were obtained from the experimental data of the structure. The nonproportional damping matrix was identified through the proposed method. Two numerical examples (lumped-mass model and cantilever beam model) were considered to verify the performance of the proposed method. As a result, the damping matrix of the nonproportional system was accurately identified.

3 Channel Measurement Technique Applied to Measure the Low Frequency Region Frequency Response Function (저주파수 영역 주파수 응답함수 측정에 대한 3채널 측정법의 적용)

  • 김경호;한상보
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.74-79
    • /
    • 1995
  • 모우드 밀도의 산정을 정확하게 구하기 위해 고주파수 영역에서 흔히 적용되는 3채널 측정법이 저주파수대 영역에서도 2채널법에 의한 방법보다 주파수 응답함수의 크기 및 공전주파수의 위치를 보다 더 잘 나타내 주고 있다는 것을 실험적으로 제시하였다. 2채널 측정법에 비하여 3채널 측정법이 모우드 밀도가 균일한 보의 경우에 있어서도 주파수 응답함수의 크기를 실제의 경우와 근접하게 추정해 줄 수 있을 뿐 아니라, 상대적으로 모우드 밀도가 높은 평판의 경우에 있어서도 공진주파수 대에서의 주파수 응답함수의 형태를 보다 분명히 나타내어 줄 수 있는 것으로 나타났다. 한편, 구조물과 가진기의 상호작용에 의한 고유진동수의 변동량 측정의 관점에서는 2채널 측정법과 3채널 측정법의 경우 모두 주파수 응답함수를 적절히 나타내어 주고 있는 것으로 나타났다.

  • PDF

Response Characteristics of Forced Vibration Model with Sinusoidal Exciting Force (정현파로 가진한 강제진동 해석과 응답특성)

  • Kim, Jong-Do;Yoon, Moon-Chul
    • Journal of Convergence for Information Technology
    • /
    • v.10 no.7
    • /
    • pp.131-137
    • /
    • 2020
  • The characteristics of forced vibration with excited sinusoidal force was introduced. Also, numerical analyses and FRF in frequency domain were performed in detail. In this regard, the responses of displacement, velocity and acceleration were investigated in a forced vibration model. The FRF characteristics in real and imaginary part around natural frequency are also discussed. This response approach of forced vibration in time domain is used for the identification and monitoring of sinusoidal forced vibration. For acquiring a displacement, velocity and acceleration, a numerical technique of Runge-Kutta-Gill method was performed. For the FRF(frequency response function), These responses are used. Also, the FRF can represent the intrinsic characteristics of the forced vibration. These performed results and analysis are successful in each damped condition for the forced vibration model. After numerical analysis of the different mass, damping and stiffness, the forced vibration response characteristics with sinusoidal force was discriminated considering its amplitude and frequency simultaneously.

Derivation the Correction of the Component of the Recorder and the Application of Hilbert Transformation to Calculating the Frequency Response of the Sensor (지진기록계 보정과 힐버트 변환 적용에 의한 센서 주파수 응답 계산)

  • Cho, Chang Soo
    • Geophysics and Geophysical Exploration
    • /
    • v.19 no.2
    • /
    • pp.84-90
    • /
    • 2016
  • The validation of performance test for newly developed or old-used sensor is very important in the earthquake monitoring and seismology using earthquake data. Especially the frequency response of the sensor is mainly used to correct the earthquake data. The technique of the calculation of phase and amplitude with Hilbert transformation for earthquake data that is filtered with band limited frequency in time domain is applied to calculate the frequency response of the sensor. This technique was tested for the acceleration sensors, CMG-5T of 1g and 2g installed on the vibration table at the laboratory and we could obtain satisfactory result. Tohoku large earthquake in 2011 observed at the station SNU that has accelerometer, ES-T and seismometer, STS-2 operated by KIGAM was also used to test the field data applicability. We could successfully get the low frequency response of broad band sensor, STS-2. The technique by using band limited frequency filter and Hilbert transformation showed the superior frequency response to the frequency spectrum ratio method for noisy part in data.