• Title/Summary/Keyword: Spectrum Analysis

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Study on the Improvement of Response Spectrum Analysis of Pile-supported Wharf with Virtual Fixed Point (가상고정점기법이 적용된 잔교식 구조물의 응답스펙트 럼해석법 개선사항 도출 연구)

  • Yun, Jung Won;Han, Jin Tae
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.6
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    • pp.311-322
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    • 2018
  • As a method of seismic-design for pile-supported wharves, equivalent static analysis, response spectrum analysis, and time history analysis method are applied. Among them, the response spectrum analysis is widely used to obtain the maximum response of a structure. Because the ground is not modeled in the response spectrum analysis of pile-supported wharves, the amplified input ground acceleration should be calculated by ground classification or seismic response analysis. However, it is difficult to calculate the input ground acceleration through ground classification because the pile-supported wharf is build on inclined ground, the methods to calculate the input ground acceleration proposed in the standards are different. Therefore, in this study, the dynamic centrifuge model tests and the response spectrum analysis were carried out to calculate the appropriate input ground acceleration. The pile moment in response spectrum analysis and the dynamic centrifuge model tests were compared. As a result of comparison, it was shown that the response spectrum analysis results using the amplified acceleration in the ground surface were appropriate.

Basic ]Requirements for Spectrum Analysis of Electroencephalographic Effects of Central Acting Drugs (중추성 작용 약물의 뇌파 효과의 정량화를 위한 스펙트럼 분석에 필요한 기본적 조건의 검토)

  • 임선희;권지숙;김기민;박상진;정성훈;이만기
    • Biomolecules & Therapeutics
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    • v.8 no.1
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    • pp.63-72
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    • 2000
  • We intended to show some basic requirements for spectrum analysis of electroencephalogram (EEG) by visualizing the differences of the results according to different values of some parameters for analysis. Spectrum analysis is the most popular technique applied for the quantitative analysis of the electroen- cephalographic signals. Each step from signal acquisition through spectrum analysis to presentation of parameters was examined with providing some different values of parameters. The steps are:(1) signal acquisition; (2) spectrum analysis; (3) parameter extractions; and (4) presentation of results. In the step of signal acquisition, filtering and amplification of signal should be considered and sampling rate for analog-to-digital conversion is two-time faster than highest frequency component of signal. For the spectrum analysis, the length of signal or epoch size transformed to a function on frequency domain by courier transform is important. Win dowing method applied for the pre-processing before the analysis should be considered for reducing leakage problem. In the step of parameter extraction, data reduction has to be considered so that statistical comparison can be used in appropriate number of parameters. Generally, the log of power of all bands is derived from the spectrum. For good visualization and quantitative evaluation of time course of the parameters are presented in chronospectrogram.

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Mobility-Spectrum Analysis of an Anisotropic Material System with a Single-Valley Indirect-Band-Gap Semiconductor Quantum-Well

  • Joung, Hodoug;Ahn, Il-Ho;Yang, Woochul;Kim, Deuk Young
    • Electronic Materials Letters
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    • v.14 no.6
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    • pp.774-783
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    • 2018
  • Full maximum-entropy mobility-spectrum analysis (FMEMSA) is the best algorithm among mobility spectrum analyses by which we can obtain a set of partial-conductivities associated with mobility values (mobility spectrum) by analyzing magnetic-field-dependent conductivity-tensors. However, it is restricted to a direct band-gap semiconductor and should be modified for materials with other band structures. We developed the modified version of FMEMSA which is appropriate for a material with a single anisotropic valley, or an indirect-band-gap semiconductor quantum-well with a single non-degenerate conduction-band valley e.g., (110)-oriented AlAs quantum wells with a single anisotropic valley. To demonstrate the reliability of the modified version, we applied it to several sets of synthetic measurement datasets. The results demonstrated that, unlike existing FMEMSA, the modified version could produce accurate mobility spectra of materials with a single anisotropic valley.

The Estimation of the Floor Vibration in Structure for Application of Response Spectrum Analysis Method (응답스펙트럼 해석법을 이용한 건축 구조물의 바닥진동해석)

  • 이동근;김태호
    • Journal of the Earthquake Engineering Society of Korea
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    • v.2 no.4
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    • pp.169-178
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    • 1998
  • In general, the response spectrum analysis method is widely used for seismic analysis of building structures, and the time history analysis is applied for computation of structural vibration caused by equipments, machines and moving loads, etc. However, compared with the response spectrum analysis method, the time history method is very complex, difficult and time consuming. In this study, the maximum responses for the vertical vibration are calculated conveniently by the response spectrum method. At first, Response spectrum and time history analysis for some earthquake excitations are carried out, and the accuracy of maximum displacements obtained from response spectrum analysis is investigated. Secondly, the process for the response spectrum analysis in excitation is calculated, and the maximum modal responses are combined by CQC method. Finally, results of the proposed method are compared with those of the time history analysis.

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Simulation of a Non-Directional Wave Spectrum Analysis with Welch's Method

  • Park, Soo-Hong
    • Journal of information and communication convergence engineering
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    • v.6 no.2
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    • pp.146-149
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    • 2008
  • Simulation and signal conditioning on the time domain surface elevation records are conducted to verify the proposed Welch's method in non-directional ocean wave spectrum analysis. These spectrum data are further conditioned to provide wave characteristic that better describe the sea states. Comparison of significant wave height and zero crossing period between the proposed method and a reference toolkit are presented.

Evaluation of the Seismic Integrity of a Centrifugal Pump using Response Spectrum Analysis (응답 스펙트럼 해석을 이용한 원심펌프의 내진 건전성 평가)

  • Choi, Myung-Jin;Yoo, Ji-Woo
    • Journal of the Korean Institute of Gas
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    • v.14 no.6
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    • pp.44-50
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    • 2010
  • Vibration responses of a centrifugal pump required dynamic analysis for seismic qualification, were calculated by using spectrum analysis, which is known to be very simple compared with time domain analysis. Modal analysis was performed and the results were utilized in the spectrum analysis. The vibration responses calculated from the spectrum analysis were more conservative than those from the time domain analysis, that is, the former can be used as safer in design process. The pump was qualified for the specified seismic service conditions as specified in IEEE 344-1987. The maximum stresses were less than allowable stress limits. Based on the analysis results, it is concluded that the pump meets all the dynamic requirements of the applicable codes, standards, and technical specification.

FREQUENCY SPECTRUM ANALYSIS OF ACOUSTIC EMISSION OF HARD DISK DRIVE HEAD/DISK INTERACTION

  • Chung, K.H.;Oh, J.K.;Moon, J.T.;Kim, D.E.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.273-274
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    • 2002
  • In order to evaluate the flying characteristics of slider, the acoustic emission (AE) as well as friction signals are typically utilized. In this work the frequency spectrum analysis is performed using the AE signal obtained during the head/disk interaction such as load/unload mechanism using ramp, impact situation in the presence of a bump on disk surface and other contact phenomena including particle interaction. It was shown that the influence of impact can be characterized effectively in the AE frequency spectrum. As a result of this work, frequency spectrum analysis will be utilized with better understanding for studying the head/disk interface (HDI) characteristics and monitoring the particle interaction in HDI effectively.

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Nondestructive Evaluation of Creep Damage Materials by using Ultrasonic Spectrum Analysis (초음파 Spectrum 해석에 의한 Creep 손상재의 비파괴평가)

  • Kim, C.I.;Yi, W.;Lim, Y.H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.11 no.2
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    • pp.42-47
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    • 1991
  • Nondestructive evaluation study was made on creep damage materials by ultrasonic spectrum analysis. The evaluation methods was developed in order to predict the change of ultrasonic attenuation with increasing creep damage. A new algorithm for the improvement of measuring accuracy of ultrasonic attenuation using a spectrum analysis has been developed. Normally, the ultrasonic attenuation is evaluated from 1st and 2nd peak values of the pulse-echo ultrasonic wave. The algorithm developed is incorporated in a measuring system which consists of a personal computer with ultrasonic apparatus and a digital storage oscilloscope. By the spectrum analysis method, it become popssible to describe approximately the attenuation change with increassing creep damage in Cr-Mo-V forging.

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Efficient Seismic Analysis of Bridge by Single Mode Spectrum Analysis Method (단일모드 스펙트럼해석법에 의한 교량의 효율적 내진해석)

  • 박윤봉;국무성;유승운;김선훈
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.487-494
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    • 2003
  • Recently it is used seismic analysis like single mode spectrum analysis, multi mode spectrum analysis and time history analysis in Korea. Because bridges are not special form of them but regular and simple form of them in our country, we must develope seismic analysis program of bridge based on single nude spectrum analysis. The program developed by this study reduces a Quantity and a time of calculation compared to SAP90 and gives accurate answers without errors. In the case of commercial program if we look for seismic load(P/sub e/(x)), we must increase the number of node and the larger the number of node the more a quantity and a time of calculation. But this program is exactly solved with basic node compared to commercial program.

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Spectrum analysis for assessing red blood cell aggregation using high-frequency ultrasound array transducer

  • Yoon, Changhan
    • Biomedical Engineering Letters
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    • v.7 no.4
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    • pp.273-279
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    • 2017
  • The purpose of this study is to investigate a spectrum analysis technique for detecting and monitoring red blood cell (RBC) aggregation using a high-frequency array transducer. To assess the feasibility of this approach, the backscattered radio-frequency signal from non-aggregated and aggregated RBC samples with two hematocrit levels were acquired by using a 30-MHz linear array transducer and analyzed in frequency domain. Three parameters such as spectral slope, midband fit and Y intercept were extracted in a static condition. Fresh porcine blood was used and degrees of aggregation were changed by diluting plasma concentration. From the experiments, it was demonstrated that the spectral slope related to a size of scatterer progressively declined as the level of aggregation increased; its mean values at hematocrit of 40% were 1.10 and -0.22 dB/MHz for RBCs suspended in isotonic phosphate buffered saline and solution with 70% plasma concentrations, respectively. For the midband fit and Y intercept, the mean values were increased by 9.1 and 46.4 dB, respectively. These results indicated that the spectrum analysis technique is useful for monitoring RBC aggregation and can be potentially developed for assessing aggregation in clinical applications.