• Title, Summary, Keyword: 변위

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Reliability Analysis of the Three-Dimensional Deformation Measurement by Terrestrial Photogrammetry (지상사진에 의한 삼차원변형측량의 신뢰성 분석(기이))

  • 유복모;유환희;이용희
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.6 no.1
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    • pp.35-41
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    • 1988
  • In the three dimensional deformation analysis by terrestrial photographs, iterative reweighted similarity transformation method is used for more accurate displacement computation. Also, Bayesian Inference method is used in the detection of unstable points and the analytical method for displacement patterns analysis is proposed in this study. In results, the accuracy of displacement estimation was improved by applying the weights of least absolute method ($\Sigma$|d|⇒min) and more accurate detection of displaced points could be achieved by Bayesian Inference. The analytical method in the patterns of displacement proposed in this study could be adapted to the movement analysis of objects wholly or partly.

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A Study on Behavior of the Earth Retaining Structure by Field Measurement and Numerical Analysis (현장계측과 수치해석에 의한 흙막이구조물의 거동 비교분석)

  • Wo, Jongtae
    • Journal of the Society of Disaster Information
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    • v.13 no.3
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    • pp.286-295
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    • 2017
  • In this study, it is compared various coefficients of subgrade reaction for application of numerical analysis based on measured data by using various theories and empirical formula. The ratio of the maximum and minimum value is 6.80 at the top of wall but it is 1.06 at the maximum displacement point depends on change of calculated coefficient of subgrade reaction. The data of displacement were generally similar considering an increment of a coefficient of subgrade reaction. And the results of comparison of the displacement at the maximum displacement point by numerical analysis and measured data show similar displacement shape.

Displacement Based Seismic Performance Improved Design of RC Column Retrofitted Steel Jacket (변위기반 설계법에 의한 RC 기둥의 Steel Jacket 보강 내진성능개선 설계법)

  • Jung, In-Kju;Cho, Chang-Geun;Park, Soon-Eung
    • Journal of Korean Association for Spatial Structures
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    • v.10 no.4
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    • pp.49-57
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    • 2010
  • This study is the research appling the representative Displacement-Based Design which is the basic concept of Direct Displacement Based Design proposed by Chopra and Goel to original Reinforced Concrete structure and determining the thickness of retrofit Steel Jacket about the Maximum design ground acceleration, and developing the more improved Algorithm as well as program by the Retrofit Design method and Nonlinear analysis by the Performance design method before and after reinforcement appling the determined retrofit thickness. To predict the target displacement of retrofitted columns, a nonlinear analysis model of reinforced concrete columns has been developed to be based on the nonlinear fiber cross-sectional and segmental analysis model, and the seismic displacement level of retrofitted columns is estimated by two procedures, the direct displacement-based design method and the displacement coefficient method. In examples of seismic retrofit design, the current seismic improved design method gives good results in improvements of displacement levels and displacement ductilities of retrofitted columns.

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A Probe of Fiber Optic OTDR Displacement Sensor (광섬유 OTDR변위 센서의 탐촉자)

  • Kwon, Il-Bum;Kim, Chi-Yeop;Seo, Dae-Cheol
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.5
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    • pp.350-355
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    • 2005
  • The probes of fiber optic OTDR (Optical Time Domain Reflectometry) sensor was developed to measure displacements of social infrastructures. This probe was simply constructed with two conventional optical fiber connectors, and a fiber bending part, which transforms displacement to optical loss. When the displacement was affected on the bending loss part, the reflected light intensity of one optical connector was changed. The displacement was determined from this reflected light intensity change of the connector. fiber optic OTDR displacement sensor was developed as the multiplexed type of one fiber line with 5 sensor probes. Multiplexing operation was tested by these 5 sensor probes.

Development of Performance-Based Seismic Design of RC Column Retrofitted By FRP Jacket using Direct Displacement-Based Design (직접변위기반설계법에 의한 철근콘크리트 기둥의 FRP 피복보강 내진성능설계법의 개발)

  • Cho, Chang-Geun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.2
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    • pp.105-113
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    • 2007
  • In the current research, an algorithm of performance-based seismic retrofit design of reinforced concrete columns using FRP jacket has been proposed. For exact prediction of the nonlinear flexural analysis or FRP composite RC members, multiaxial constitutive laws of concrete and composite materials have been presented. For seismic retrofit design, an algorithm of direct displacement-based design method (DDM) proposed by Chopra and Goel (2001) has been newly applied to determine the design thickness of FRP jacket in seismic retrofit of reinforced concrete columns. To compare with the displacement coefficient method (DCM), the DDM gives an accurate prediction of the target displacement in highly nonlinear region, since the DCM uses the elastic stiffness before reaching the yield load as the effective stiffness but the DDM uses the secant stiffness.

Effect of the Incident Optical Spot Size Upon the Quadrant Photodetector on the Optical Displacement Detection Sensitivity (4분할 광 검출기 상의 광점 크기가 변위 측정감도에 미치는 영향)

  • Lee, Eun-Joong;Lee, Jin-Woo;Kouh, Tae-Joon
    • Journal of the Korean Magnetics Society
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    • v.18 no.2
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    • pp.71-74
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    • 2008
  • In this paper, we have measured the effect of the optical spot size, incident upon the quadrant photodetector, on the optical displacement sensitivity of the optical beam deflection technique. We have built an optical displacement detection system based on the optical beam deflection method using 3 mW He-Ne laser and measured the displacement sensitivity with changing the optical spot size on the quadrant photodetector. We have also calculated the changes in the optical displacement sensitivity as a function of the incident laser spot size by modeling a circular optical spot with constant laser intensity. Our experimental and theoretical studies show that the optical displacement sensitivity increases with the decrease in the optical spot size. This suggests that in the design of the optical motion detection systems with sub-nanometer sensitivity, the displacement sensitivity can be optimized by reducing the size of the incident optical spot on the detector.

Improvement of Medical Ultrasound Strain Image Using Lateral Motion Compensation (측방향 움직임 보상을 이용한 초음파 의료용 변형률 영상의 화질개선)

  • Park, Myung-Ki;Kwon, Sung-Jae;Jeong, Mok-Kun
    • The Journal of the Acoustical Society of Korea
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    • v.30 no.5
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    • pp.239-248
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    • 2011
  • In order to improve the quality of strain images in medical ultrasound imaging, displacements need to be accurately estimated. In this paper, in order to apply one-dimensional displacement estimation methods to two-dimensional motion estimation, the axial and lateral displacements are separately estimated. In order to estimate lateral displacements, one-dimensional signals aligned in the lateral direction are converted to analytic signals, which are then crosscorrelated. Strain images are produced by first compensating two-dimensional displacements for lateral motion with lateral motion displacement estimates obtained from the proposed lateral displacement estimation algorithm and then estimating axial displacements. Both phantom and human data experiments show that the proposed method provides better signal-to-noise ratio and contrast-to-noise ratio characteristics than a conventional strain imaging method that utilizes axial displacement estimates only.

Determination of Optimal Locations for Measuring Displacements to Adjust Cable Tension Forces of Cable-Stayed Bridges (사장교 시공 중 케이블 장력 보정을 위한 최적 변위계측 위치 결정)

  • Shin, Soobong;Lee, Jung-Yong;Kim, Jae-Cheon;Jung, Kil-Je
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.2
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    • pp.129-136
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    • 2009
  • The paper presents an algorithm of selecting optimal locations for measuring displacements(OLD) to adjust cable tension forces during the construction of cable-stayed bridges. The rank for optimal locations can be determined from the effective independence distribution vectors(EIDV) that are computed from the Fisher Information Matrices(FIM) formulated with the displacement sensitivities. To examine the efficiency and reliability of the proposed algorithm for determining OLD, a simulation study on a cable-stayed bridge has been carried out. The results using FIM formulated with displacements are compared with those using FIM with displacement sensitivities through the simulation study. The effects of measurement noise and error in cable length on the adjustment of cable tension forces are evaluated statistically by applying the Monte Carlo scheme.

Measurement of Absolute Displacement-Amplitude of Ultrasonic Wave Using Piezo-Electric Detection Method (압전형 수신 기법을 이용한 초음파 절대변위진폭 측정)

  • Park, Seong-Hyun;Kim, Jongbeom;Jhang, Kyung-Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.37 no.1
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    • pp.7-12
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    • 2017
  • A nonlinear ultrasonic parameter is defined by the ratio of displacement amplitude of the fundamental frequency component to that of the second-order harmonic frequency component. In this study, the ultrasonic displacement amplitude of an SUS316 specimen was measured via a piezo-electric-based method to identify the validity of piezo-electric detection method. For comparison, the ultrasonic displacement was also determined via a laser-based Fabry-Pérot interferometer. The experimental results for both measurements were in good agreement. Additionally, the stability of the repeated test results from the piezo-electric method exceeded that of the laser-interferometric method. This result indicated that the piezo-electric detection method can be utilized to measure a nonlinear ultrasonic parameter due to its excellent stability although it involves a complicated process.

Development of Resizing Techniques for Drift Designs of High-rise Buildings subjected to Lateral and Vertical Loads (횡하중과 연직하중을 받는 고층건물의 변위설계를 위한 재분배기법 개발)

  • 서지현;박효선
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.17 no.1
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    • pp.49-58
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    • 2004
  • Drift design of a high-rise building is a governing factor in the determination of structural weights and lateral resisting systems. However, high-rise buildings are composed of tens of thousands of structural member, designer can not know which members are active to lateral drift control and how much they contribute to lateral drifts. Resizing technique was proved to be a practical method for drift design of high-rise buildings. However, no resizing algorithm has been considered the effect of vertical loads in drift designs. Thus, in this paper, a resizing algorithm has been developed for drift designs of high-rise buildings subjected to both lateral and vertical loads. The drift design model has been applied to drift designs of two high-rise building examples.