• Title, Summary, Keyword: phase error

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Phase error compensation for three-dimensional shape measurement based on a phase-shifting method (위상천이법을 이용한 삼차원 형상측정에서 위상오차 보정)

  • Park, Yoon-Chang;Ahn, Seong-Joon;Kang, Moon-Ho;Kwon, Young-Chul;Ahn, Seung-Joon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.11
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    • pp.3023-3030
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    • 2009
  • In this paper, a prediction and compensation method for the error in the phase measured by using the proportionality between two wavelengths in the TW-PMP (Two-wavelength Phase Measuring Profilometry) is proposed and experimental results are shown to verify the usefulness of the proposed method. For sample object, firstly, a phase-shifting with a quite large number of steps is adopted in measurement, compared with the conventional phase-shifting method, secondly, a 3-3 step phase-shifting method is used to measure the same object which is applied to high-speed 3D shape measurement, and then, measured results from these two phase-shifting methods are compared to calculate measurement noises. From the experimental results applying the proposed compensation method to the measured beat phase and absolute phase, it has proven that noises are decreased by 90% and 17.2% for each case.

Analysis of Optical Transfer Function and Phase Error of the Modified Triangular Interferometer

  • Kim, Soo-Gil;Ryeom, Jeong-Duk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.1
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    • pp.10-18
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    • 2007
  • We synthesize and analyze the optical transfer function(OTF) of the modified triangular interferometer(MTI) using two-pupil synthesis method and we present the optimal MTI, which can obtain any bipolar function by combining a wave plate and a linear polarizer. Also, we analyze its potential phase error sources caused by polarization components.

Digital Control of a Single-Phase UPS Inverter for Robust AC-Voltage Tracking

  • Woo Young-Tae;Kim Young-Chol
    • International Journal of Control, Automation, and Systems
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    • v.3 no.4
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    • pp.620-630
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    • 2005
  • This paper presents a digital controller for a single phase UPS inverter under two main considerations: (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load conditions, and (ii) the digital controller shall be employed at a fixed sampling time. We propose that the former can be achieved by the proposed controller using the error-state approach and the latter can be dealt with by the socalled characteristics ration assignment.

Analysis of Phase Error Due to the Azimuth Angle of the Wave Plates in the Shearography Using Wollaston Prism (Wollaston prism을 이용한 스펙클패턴 전단간섭법에 있어서 파장판의 방위각에 의한 위상오차 해석)

  • Kim, Soo-Gil;Kim, Ki-Soo;Ko, Myung-Sook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.8
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    • pp.1-7
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    • 2005
  • We introduced the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by the polarizing elements, and calculate the phase at each point of the speckle pattern in shearography using Wollaston prism and polarizing elements. Ant we analyzed the phase error caused by the azimuth angles of wave plates used in the proposed method by Jones matrix.

Phase Error Analysis in Shearography Using Wave Plates (파장판를 이용한 스펙클패턴 전단간섭법에 있어서의 위상오차 해석)

  • Kim, Soo-Gil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.1
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    • pp.34-39
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    • 2005
  • We presented the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by passive devices such as wave plate and polarizer, and calculate the phase at each point of the speckle pattern in shearography using Wollaston prism. And, we analyzed the phase error caused by wave plates used in the proposed method by Jones matrix.

Compensation Method of Current Measurement Error for Vector-Controlled Inverter of 2-Phase Induction Motor (2상 유도전동기용 벡터제어 인버터를 위한 전류측정 오차 보상 방법)

  • Lee, Ho-Jun;Yoon, Duck-Yong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.7
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    • pp.1204-1210
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    • 2016
  • The phase currents must be accurately measured to achieve the instantaneous torque control of AC motors. In general, those are measured using the current sensors. However, the measured current signals can include the offset errors and scaling errors by several components such as current sensors, analog amplifiers, noise filter circuits, and analog-to-digital converters. Therefore, the torque-controlled performance can be deteriorated by the current measurement errors. In this paper we have analyzed the influence caused by vector control of 2-phase induction motor when two errors are included in measured phase currents. Based on analyzed results, the compensation method is proposed without additional hardware. The proposed compensation method was applied vector-controlled inverter for 2-phase induction motor of 360[W] class and verified through computer simulations and experiments.

Bit Error Probability of $\pi$/4-DQPSK with Stepped Phase over a Frequency Selective Fading Channel (주파수선택성 페이딩전송로에서 스텝형 위상을 갖는 $\pi$/4-DQPSK의 비트오율)

  • 이철성;이재홍
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.9
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    • pp.1177-1183
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    • 1995
  • This paper proposes a new modulation scheme of $\pi$/4-DQPSK with stepped phase for a frequency selective fading channel. In the proposed modulation scheme, the phase of transmitted signal is shifted in the mid of a symbol duration in order to reduce the effect of multipath delay spread. It reduces the irreducible error of $\pi$/4-DQPSK over a frequency selective fading channel. It is shown that $\pi$/4-DQPSK with stepped phase achieves smaller average bit error probability than regular $\pi$/4- DQPSK by simulation. The former achieves much smaller average bit error probability than the latter for small TEX>${\tau}/T_{s}$.

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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.

Performance Analysis of DS-CDMA System of Phase Estimation Error for Mobile Satellite Wireless Communication Channel (이동위성 무선통신 채널에서 위상추정 에러가 있는 DS-CDMA 시스템의 성능 해석)

  • Kang, Heau-Jo
    • The Journal of Advanced Navigation Technology
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    • v.11 no.2
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    • pp.170-176
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    • 2007
  • In this paper, we improve performance for system when the carrier recovery signal is not perfect in the multipath mobile wireless communication fast fading channel based on DS-CDMA system. In the case, we use the phase estimation, diversity and adaptive FEC code technique in order to overcome this carrier phase error and mobile wireless fading. As a results in DS-CDMA system, we know that the appropriate use of diversity and adaptive FEC code technique reduced considerably performance degradation due to phase error.

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The Phase Shift and Phase Error Analysis in the Shearographic System (Shearographic system에서의 위상천이 및 위상오차 분석)

  • Kim, Soo-Gil;Ko, Myung-Sook
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.143-145
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    • 2005
  • We present the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ passive devices such as wave plate and polarizer, and calculate the phase at each point of the speckle pattern in shearographic system using Wollaston pin And, we analyzed the phase error caused by wave plates used in the proposed method by Jones matrix.

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