• Title/Summary/Keyword: Displacement Error

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Evaluation Technique for Ratio Error and Phase Displacement of Current Transformer Comparator (전류변성기 비교기의 비오차 및 위상오차 평가기술)

  • Kim, Yoon-Hyoung;Han, Sang-Gil;Jung, Jae-Kap;Han, Sang-Ok
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.4
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    • pp.437-443
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    • 2008
  • We have developed an evaluation technique for both ratio error and phase displacement of current transformer (CT) comparator by using the precise standard capacitors and resistors. By applying this technique to equivalent circuit of CT comparator evaluation system, we can obtain the calculated and measured ratio errors (or phase displacements) in the CT comparator. Thus we can evaluate ratio errors and phase displacement of CT comparator by comparing the calculated and measured ratio errors (or phase displacements). The method was applied to CT comparator under test with the ratio errors and phase displacement ranges of $0{\sim}{\pm}10%$ and $0{\sim}{\pm}7.5$ crad, respectively. Finally we have compared the ratio error and phase displacement of the CT comparator obtained in this method with specifications of two companies.

Effects of Geometric Errors on the Measurement of Error Motions of Rotor with the Cylindrical Capacitive Displacement Sensor (형상오차가 원통형 정전용량 변위센서의 축 회전오차의 측정에 미치는 영향)

  • 안형준;장인배;한동철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.487-490
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    • 1995
  • This paper discisses the effects geometric errors on the measurement of error motions of rotor with the cylindrical capacitive displacement sensor. Analytic model of the measuring process with this sensor is derived and this model shows that the effect of geometric errors of sensor is larger than that of rator on the measurement of error motions of rotor. The computer simulation shows effect of periodic errors in this sensor on the measuring orbit.

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Extension of Absolute Evaluation Technique for Ratio Error and Phase Displacement of Core Type Current Transformers: Ip =$5\;kA{\sim}40\;kA$ (철심형 전류변성기의 비오차 및 위상오차 절대 평가 기술의 확장 : 1차 전류 = $5\;kA{\sim}40\;kA$)

  • Kim, Yoon-Hyoung;Han, Sang-Gil;Jung, Jae-Kap;Han, Sang-Ok
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.4
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    • pp.431-436
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    • 2008
  • We have extended an absolute evaluation method to obtain the ratio error and phase displacement of a current transformer (CT) up to primary current of 40,000 A by measuring four parameters of equivalent circuit in CT. The method was applied to CTs under test with the current ratios in the range of 5,000 A / 5 A - 40,000 A / 5 A. The ratio error and phase displacement of the CTs under test obtained in this study are consistent with those measured at the national institutes in Canada and Germany using the same CTs under test within an expanded uncertainty (k = 2) in the overall current ratios.

Moving Pixel Displacement Detection using Correlation Functions on CIS Image

  • Ryu, Kwang-Ryol;Kim, Young-Bin
    • Journal of information and communication convergence engineering
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    • v.8 no.4
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    • pp.349-354
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    • 2010
  • Moving pixel displacement detection algorithm using correlation functions for making panorama image on the continuous images is presented in this paper. The input images get from a CMOS image sensor (CIS). The camera is maintained by constant brightness and uniform sensing area in test input pattern. For simple navigation and capture image has to 70% overlapped region. A correlation rate in two image data is evaluated by using reference image with first captures, and compare image with next captures. The displacement of the two images are expressed to second order function of x, y and solved with finding the coefficient in second order function. That results in the change in the peak correlation displacement from the reference to the compare image, is moving to pixel length. The navigating error is reduced by varying the path because the error is shown in the difference of the positioning vector between the true pixel position and the navigated pixel position. The algorithm performance is evaluated to be different from the error vector to vary the navigating path grid.

Probability-based prediction of residual displacement for SDOF using nonlinear static analysis

  • Feng, Zhibin;Gong, Jinxin
    • Earthquakes and Structures
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    • v.22 no.6
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    • pp.571-584
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    • 2022
  • The residual displacement ratio (RDRs) response spectra have been generally used as an important means to evaluate the post-earthquake repairability, and the ratios of residual to maximum inelastic displacement are considered to be more appropriate for development of the spectra. This methodology, however, assumes that the expected residual displacement can be computed as the product of the RDRs and maximum inelastic displacement, without considering the correlation between these two variables, which inevitably introduces potential systematic error. For providing an adequately accurate estimate of residual displacement, while accounting for the collapse resistance performance prior to the repairability evaluation, a probability-based procedure to estimate the residual displacement demands using the nonlinear static analysis (NSA) is developed for single-degree-of-freedom (SDOF) systems. To this end, the energy-based equivalent damping ratio used for NSA is revised to obtain the maximum displacement coincident with the nonlinear time history analysis (NTHA) results in the mean sense. Then, the possible systematic error resulted from RDRs spectra methodology is examined based on the NTHA results of SDOF systems. Finally, the statistical relation between the residual displacement and the NSA-based maximum displacement is established. The results indicate that the energy-based equivalent damping ratio will underestimate the damping for short period ranges, and overestimate the damping for longer period ranges. The RDRs spectra methodology generally leads to the results being non-conservative, depending on post-yield stiffness. The proposed approach emphasizes that the repairability evaluation should be based on the premise of no collapse, which matches with the current performance-based seismic assessment procedure.

Influence of Zero Reading on Predicting Crown Displacement of Tunnel (초기계측 시점이 터널 내공변위 예측에 미치는 영향분석)

  • Kim, Kwang-Yeom;Kim, Ho-Geun;Seo, Youg-Seok
    • Tunnel and Underground Space
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    • v.22 no.3
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    • pp.214-220
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    • 2012
  • Deformation behaviour of rock mass around an opening measured during tunnel excavation is very important in order to assess the stability of the tunnel. Unfortunately displacement measured only after the installation of displacement measuring device can be acquired, which results in inevitably excluding the pre-displacement occurred and accumulated before the displacement measuring devices are installed. So it is very important to consider the pre-displacement based on the elapsed time before zero reading after deformation behaviour started. In this study, the accuracy of total estimated displacement depending on the distance between face and measurement position is calculated by statistical non-linear fitting on measurable displacement data. Besides, the influence of the unavoidable measurement error is considered by using Monte-Carlo simulation. As a result, the faster the initial reading started and the smaller the measurement error is, the higher the accuracy of estimating total displacement is obtained.

Development of Computer Aided Measurement and Compensation System for Linear Pitch Error Correction in CNC Machine Tools Implementing a New Optimal Correction Algorithm (CNC 공작기계 선형피치오차의 최적 보정알고리즘을 구현하는 자동 측정 및 보정 시스템의 개발)

  • 이석원;박희재;주종남
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.1
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    • pp.69-77
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    • 1998
  • Linear displacement accuracy is one of the most important factors that determine machine tool accuracy The laser interferometer has been usually recommended for the measurement of linear displacement accuracy. In this paper, microcomputer aided measurement and compensation system has been developed for the pitch error in a CNC machine tool. For accurate pitch error calculation. the analysis code for the pitch error has been also implemented according to the international standards (ISO). The PC based automatic compensation system for the pitch error is also implemented. A new algorithm for calculating optimum value for pitch error compensation is proposed, minimizing the deviation at each target points. The development system has been applied to a practical CNC maching center and the performance has been demonstrated.

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