• Title/Summary/Keyword: 힐버트 변환

Search Result 72, Processing Time 0.038 seconds

Application of Minimum Phase Condition to Acoustic Impedance Measurement (최소 위상 조건을 적용한 음향 임피던스 측정)

  • Lim, Byoung-Duk;Heo, Jun-Hyeok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.05a
    • /
    • pp.855-860
    • /
    • 2005
  • For the accurate measurement of acoustic properties of a surface, efforts have been made to reduce errors caused by external disturbance. If the reflection coefficient is considered as a transfer function between reflected wave and incident wave, causality is required between them and the reflection coefficient should be of minimum phase. In this thesis, the minimum phase condition is applied to measure correct reflection coefficient. The reflection coefficient is approximated as a rational function in the Z domain by minimizing the sum square error. Then the minimum phase reflection coefficient is reconstructed using the distribution of poles and zeros of the reflection coefficient model. The incident wave, the reflected wave and the impulse response function of causality are recalculated from the minimum phase reflection coefficient for further applications.

  • PDF

A Study on Vibration Reduction Timing Selection in the Mobile Pointing System (기동장비용 지향구조물의 진동 감소 상태선정 연구)

  • Yoo, Jin-Ho;Lee, Dong-Ju
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.16 no.2
    • /
    • pp.112-119
    • /
    • 2007
  • In order to predict vibration trends occurred during vehicle drive, acceleration data was processed by using data processing algorithm with moving average and Hilbert transform. Specific mode constants of acceleration were obtained under various disturbance. Vehicle velocity, road condition, property of pointing structure were considered as factors which make change of vibration trend in vehicle dynamics. Results of signal processing were compared and analysed. Advanced performance of the timing selection algorithm from this study was verified by using simple equipment comparing with the deflection measurement laser system(Muzzle Reference System).

Mode Shape Reconstruction of an impulse excited structure using HHT and CSLDV (HHT와 연속스캐닝 진동계를 이용한 임펄스가진된 구조물의 모드 형상 복원)

  • Kyong, Yong-Soo;Kim, Dae-Sung;Dayou, Jedol;Park, Kyi-Hwan;Wang, Se-Myung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2008.04a
    • /
    • pp.484-490
    • /
    • 2008
  • For CSLDV, the Chebyshev demodulation (or polynomial) technique and Hilbert transform approach have been used for mode shape reconstruction with harmonic excitation. In this paper, the Hilbert-Huang transform approach was applied as an alternative to impact excitation cases in terms of a numerical approach. The vibration of the tested structure is modeled using impulse response functions. In order to verify this technique, a simply supported beam was chosen as the test rig. With additional innovative steps which are the ideal-band pass filter and the nodal point determination, Hilbert-Huang transformation can be used for a good mode shape reconstruction even in the impact excitation case.

  • PDF

Evaluating Efficacy of Hilbert-Huang Transform in Analyzing Manufacturing Time Series Data with Periodic Components (제조업의 주기성 시계열분석에서 힐버트 황 변환의 효용성 평가)

  • Lee, Sae-Jae;Suh, Jung-Yul
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.35 no.2
    • /
    • pp.106-112
    • /
    • 2012
  • Real-life time series characteristic data has significant amount of non-stationary components, especially periodic components in nature. Extracting such components has required many ad-hoc techniques with external parameters set by users in case-by-case manner. In our study, we evaluate whether Hilbert-Huang Transform, a new tool of time-series analysis can be used for effective analysis of such data. It is divided into two points : 1) how effective it is in finding periodic components, 2) whether we can use its results directly in detecting values outside control limits, for which a traditional method such as ARIMA had been used. We use glass furnace temperature data to illustrate the method.

Investigating of a Floor-Impact Isolation System Using Damping Materials In Apartment Buildings (공동주택에서 완충재를 이용한 바닥충격음 저감 System 연구)

  • 송희수;정영;정정호;전진용
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2004.05a
    • /
    • pp.499-504
    • /
    • 2004
  • The purpose of this study is to investigate a investigating of a floor-impact isolation system using damping materials in apartment buildings. The stiffness elastic modulus(k) by puls impact forces were calculated loss factor by Hilbert transforms. It is absolved that natural frequency was moved floor shock-absorbing materials and the impact force was reduced by floor panel. The slab was constructed by damping materials. As towards a result, the system showed inverse A 45dB by heavy weight-impact noise and inverse A 52dB by light-impact noise. High frequencies impact-noise can be reduced by upgrading naturial frequency of vibration and noise in the system.

  • PDF

작용소의 틈이론

  • 정일봉;이우영
    • Communications of the Korean Mathematical Society
    • /
    • v.16 no.1
    • /
    • pp.25-66
    • /
    • 2001
  • 복소힐버트 공간상에서 정의된 작용소 중에서 최근 많이 연구되는 분야는 부분정규작용소와 초정규작용소들 들 수 있다. 본 논문에서는 작용소의 부분정규성과 초정규성 사이에 있는 작용소의 여러 성질을 살펴보고 특히 $\textsc{k}$차초정규, 이차약초정규, 삼차약초정규, 다항초정규, 토에플리츠작용소 및 약부분정규작용소에 관한 최근의 연구 결과들을 살펴보며 이와 관련되 미해결 문제들을 제시한다. 마지막으로 틈이론의 응용으로서 작용소이론의 큰 문제인 불변공간문제와의 관련성을 살펴보고 틈이론의 전망과 기타 관련정보를 소개한다.

  • PDF

Control Limits of Time Series Data using Hilbert-Huang Transform : Dealing with Nested Periods (힐버트-황 변환을 이용한 시계열 데이터 관리한계 : 중첩주기의 사례)

  • Suh, Jung-Yul;Lee, Sae Jae
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.37 no.4
    • /
    • pp.35-41
    • /
    • 2014
  • Real-life time series characteristic data has significant amount of non-stationary components, especially periodic components in nature. Extracting such components has required many ad-hoc techniques with external parameters set by users in a case-by-case manner. In this study, we used Empirical Mode Decomposition Method from Hilbert-Huang Transform to extract them in a systematic manner with least number of ad-hoc parameters set by users. After the periodic components are removed, the remaining time-series data can be analyzed with traditional methods such as ARIMA model. Then we suggest a different way of setting control chart limits for characteristic data with periodic components in addition to ARIMA components.

A Study on Improvement of Aiming Ability using Disturbance Measurement in the Ground Military Vehicle (지상무기체계에서의 외란측정을 이용한 정밀 지향성 향상 연구)

  • Yoo, Jin-Ho;Park, Byung-Hun
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.10 no.2
    • /
    • pp.12-20
    • /
    • 2007
  • The aiming ability is a key to improve the accuracy performance of the gun pointing system in the ground military vehicle. This paper describes the new detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis the vibration trends of the pointing system occurred while the vehicle driving, acceleration data obtained from vehicle was processed by using data processing algorithm with moving average and Hilbert transform. The specific mode constants of acceleration were obtained from various disturbances. Vehicle velocity, road condition and property of pointing structure were considered as factors which make the change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition of the classification of vibration signal in various driving conditions. Results of signal processing were compared with other condition result and analysed.

Signal Processing Technology for Rotating Machinery Fault Signal Diagnosis (회전기계 결함신호 진단을 위한 신호처리 기술 개발)

  • Choi, Byeong-Keun;Ahn, Byung-Hyun;Kim, Yong-Hwi;Lee, Jong-Myeong;Lee, Jeong-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2013.10a
    • /
    • pp.331-337
    • /
    • 2013
  • Acoustic Emission technique is widely applied to develop the early fault detection system, and the problem about a signal processing method for AE signal is mainly focused on. In the signal processing method, envelope analysis is a useful method to evaluate the bearing problems and Wavelet transform is a powerful method to detect faults occurred on rotating machinery. However, exact method for AE signal is not developed yet. Therefore, in this paper two methods which are Hilbert transform and DET for feature extraction. In addition, we evaluate the classification performance with varying the parameter from 2 to 15 for feature selection DET, 0.01 to 1.0 for the RBF kernel function of SVR, and the proposed algorithm achieved 94% classification accuracy with the parameter of the RBF 0.08, 12 feature selection.

  • PDF

PERIODIC DISTURBANCE AND NOISE REJECTION METHOD USING HIRBERT TRANSFORM (힐버트 변환을 이용한 주기적인 외란 및 잡음제거)

  • Na, Hee-Seung;Park, Young-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2000.11a
    • /
    • pp.443-448
    • /
    • 2000
  • In this paper, we propose a novel adaptive feedforward controller for periodic disturbance and noise cancellation, with a frequency tracking capability. It can be added to an existing feedback control system without altering the original closed-loop characteristics, which is based on adaptive algorithm. We introduce novel algorithm "Constrained AFC(adaptive feedforward controller) algorithm" that increase the convergence region regardless of the delay in the closed loop system. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the coefficients become time invariant. The proposed algorithm not only estimate the magnitude and phase of the tonal disturbance and noise but also track the frequency of the tone, which changes in quasi-static manner. The frequency tracking algorithm uses the instantaneous frequency approach based on Hilbert transform. A number of computer simulations have been carried out in order to demonstrate the effectiveness of proposed method under various conditions.

  • PDF