• Title/Summary/Keyword: 힐버트

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Development of Abnormal Behavior Monitoring of Structure using HHT (HHT를 이용한 이상거동 시점 추정 기법 개발)

  • Kim, Tae-Heon;Park, Ki-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.2
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    • pp.92-98
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    • 2015
  • Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring (SHM) technique is increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and influenced by various external loads. "Abnormal behavior point" is a moment when the structure starts vibrating abnormally and this can be detected by comparing between before and after abnormal behavior point. In other words, anomalous behavior is a sign of damage on structures and estimating the abnormal behavior point can be directly related to the safety of structure. Abnormal behavior causes damage on structures and this leads to enormous economic damage as well as damage for humans. This study proposes an estimating technique to find abnormal behavior point using Hilber-Huang Transform which is a time-frequency signal analysis technique and the proposed algorithm has been examined through laboratory tests with a bridge model using a shaking table.

History of Transcendental numbers and Open Problems (초월수의 역사와 미해결 문제)

  • Park, Choon-Sung;Ahn, Soo-Yeop
    • Journal for History of Mathematics
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    • v.23 no.3
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    • pp.57-73
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    • 2010
  • Transcendental numbers are important in the history of mathematics because their study provided that circle squaring, one of the geometric problems of antiquity that had baffled mathematicians for more than 2000 years was insoluble. Liouville established in 1844 that transcendental numbers exist. In 1874, Cantor published his first proof of the existence of transcendentals in article [10]. Louville's theorem basically can be used to prove the existence of Transcendental number as well as produce a class of transcendental numbers. The number e was proved to be transcendental by Hermite in 1873, and $\pi$ by Lindemann in 1882. In 1934, Gelfond published a complete solution to the entire seventh problem of Hilbert. Within six weeks, Schneider found another independent solution. In 1966, A. Baker established the generalization of the Gelfond-Schneider theorem. He proved that any non-vanishing linear combination of logarithms of algebraic numbers with algebraic coefficients is transcendental. This study aims to examine the concept and development of transcendental numbers and to present students with its open problems promoting a research on it any further.

Speech Dereverberation using Improved Linear Prediction Residual (개선된 선형예측 잔여를 이용한 음성의 잔향음 제거)

  • Park, Chan-Sub;Kim, Ki-Man;Kang, Suk-Youb
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.10
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    • pp.1845-1851
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    • 2007
  • Background noise and room reverberation are two causes of degradation in speech in listening situations. Many algorithms developed to enhance reverberant speech. In this paper we propose a dereverberation method for enhancement of speech using modified the linear prediction(LP) residual in reverberant room condition. The proposed dereberberation method based on the fact that the signification excitation of the vocal tract system takes place at the instant of glottal closure in voiced speech. Our method used delay information form each sensor, and we need reverberant signals from 3 sensors. We obtain a new LP residual signal using modified IP residual combination which derived form weighting of the LP residual and the Hilbert transform of LP residual. The nature of the coherently added Hilbert envelop has several large amplitude spikes because of the effects of noise and reverberation. This residual of the clean speech is used to excite the time-varying all-pole filter to obtain the enhanced speech. We achieved simulation of proposed algorithm for performance analysis in reverberation environment. The proposed algorithm improves substantially the quality of reverberant speech.

[ B+ ]-Tree based Indexing Method for Moving Object (B+-트리 기반의 이동객체 색인 기법)

  • Seo, Dong-Min;Yoo, Jae-Soo;Song, Seok-Il
    • The Journal of the Korea Contents Association
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    • v.7 no.7
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    • pp.11-23
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    • 2007
  • Applications involving moving objects require index structures to handle frequent updates of objects' locations efficiently. Several methods to index the current, the past and the future positions of moving objects have been proposed for the applications. Most of them are based on R-tree like index structures. Some researches have made efforts to improve update performance of R-trees that are actually focused on query performance. Even though the update performance is improved by researchers' efforts, the overhead and immaturity of concurrency control algorithms of R-trees makes us hesitate to choose them for moving objects. In this paper, we propose an update efficient indexing method that can be applicable for indexing the past, the current and the future locations. The proposed index is based on B+-Trees and Hilbert curve. We present an advanced Hilbert curve that adjusts automatically the order of Hilbert curve in subregions according to the data distribution and the number of data objects. Through empirical studies, we show that our strategy achieves higher response time and throughput.

Weathering Characteristics of On-Yang Gneiss using Ground Penetrating Radar (지표투과레이다(Ground Penetrating Radar)를 이용한 온양편마암의 풍화특성 고찰)

  • Shin, Sung-Ryul;Park, Boo-Seong;Jang, Won-Il
    • Geophysics and Geophysical Exploration
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    • v.2 no.1
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    • pp.1-7
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    • 1999
  • We investigated the weathering characteristics of On-Yang gneiss by means of geological survey and Ground Penetrating Radar(GPR). The results of geological survey and boring show the two sets of vertical joint and horizontal joint developed by foliation which is composed of salic and melanic layers. GPR section evidently shows foliation direction and differential weathering due to discontinuity and mineral composition of metamorphic rock. The GPR section for instantaneous phase attribute based on complex trace analysis evidently shows continuity and foliation direction of metamorphic rock. The strong reflection amplitude which is derived from the banded structure of weathered rock can be incorrectly interpreted as a reflection of bedrock. The depth of rock basement should be estimated from the overall exploration result such as boring, seismic method, and electrical resistivity method.

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Research on Channel Estimation Method in the modified ATSC system Using PN-Sequence for the Terrestrial 3D-TV broadcasting (지상파 3D-HDTV 전송을 위한 수정된 ATSC 전송 시스템에서 PN구조를 이용한 채널 추정 기법에 관한 연구)

  • Han, Jae-Shin;Ham, Na-Rye;Kim, Jung-Ho;Oh, Jong-Gyu;Kim, Joon-Tae
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.63-66
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    • 2010
  • 본 논문은 차세데 3D-TV 방송을 위해 수정된 ATSC (Modified Advanced Television Systems Committee) 시스템 [1]에서 파일럿 (Pilot)을 이용한 채널 추정 대신, PN 시퀀스 (Pseudo-Noise Sequence)를 이용한 채널 추정 방식의 문제점에 대하여 2가지 방법으로 연구하였다. PN 시퀀스를 이용하여 채널을 추정하는 TDS-OFDM (Time Domain Synchronous - Orthogonal Frequency Division Multiplexing)시스템은 QAM (Quadrature Amplitude Modulation) 변조 방식을 사용하기 때문에 수신측 PN 시퀀스의 위상 변화가 일어나지 않는다. 하지만 수정된 ATSC 시스템에서 사용하는 VSB (Vestigial Side Band)변조 방식에서 직교위상 (Quadrature) 채널을 통해 전송되는 값은 동위상 (In-Phase) 채널을 통해 전송되는 값의 단순한 힐버트 변환 (Hilbert Transform)에 의해 생성되어 불규칙한 위상 변화가 발생한다. 따라서 수정된 ATSC 시스템에서 채널 추정을 위해 PN 시퀀스를 사용하게 된다면 상관 (Correlation) 특성을 잃어버릴 것이며 올바른 채널 임펄스 응답 (Channel Impulse Response)을 얻을 수 없다.

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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 the Society of Korea Industrial and Systems Engineering
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    • v.35 no.2
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    • pp.106-112
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    • 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.

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 the Society of Korea Industrial and Systems Engineering
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    • v.37 no.4
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    • pp.35-41
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    • 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.

An Improved Algorithm for Respiration Signal Extraction from Electrocardiogram Using Instantaneous Frequency Estimation based on Hilbert Transform (힐버트 변환에 기반한 순간주파수 추정을 이용한 개선된 심전도 유도 호흡신호 추출 알고리즘)

  • Park Sung-Bin;Yi Kye-Hyoung;Kim Kyung-Hwan;Yoon Hyoung-Ro
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.10
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    • pp.733-740
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    • 2004
  • In this paper, an improved algorithm for the extraction of respiration signal from the electrocardiogram (ECG) is proposed. The whole system consists of two-lead electrocardiogram acquisition (lead Ⅰ and Ⅱ), baseline fluctuation elimination, R-wave detection, adjustment of sudden change in R-wave area using moving average, and optimal lead selection. In order to solve the problem of previous algorithms for the ECG-derived respiration (EDR) signal acquisition, we proposed a method for the optimal lead selection. An optimal EDR signal among the three EDR signals derived from each lead (and arctangent of their ratio) is selected by estimating the instantaneous frequency using the Hilbert transform, and then choosing the signal with minimum variation of the instantaneous frequency. The proposed algorithm was tested on 15 subjects, and we could obtain satisfactory respiration signals that shows high correlation (r>0.9) with the signal acquired from the chest-belt respiration sensor.

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
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    • pp.499-504
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    • 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.

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