• Title/Summary/Keyword: Phase Shift Method

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Measurement Method of the Vibration Mode Shapes Using Electro-Optic Holographic Interferometry (전자 광학적 훌로그래픽 간섭법을 이용한 진동물체의 모드형태 계측법)

  • Choi, Jang-Seob;Kang, Young-June
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.2
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    • pp.564-574
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    • 1996
  • This paper describes as Electronic Speckle Pattern Interferometry system which has been designed for measuring vibration patterns and quantitative measurement of vibration amplitude fields by using the time average method on a object. Visbility of fringe patterns is more improved by using the phase stepping and frame average method to reduce speckle and electric noise. And a bias vibration is introduced into the reference beam to shift the $\frac{2}{0}$ fringes so that fringe shift algorithms can be used to determine vibration amplitude. The experimental results are compared to those of the FFT analyzer and the FEM model analysis.

Phase unwrapping enhancement of phase shift interferometry by using lateral scanning (횡방향 주사를 이용한 광위상 간섭계의 페이즈 언래핑 향상에 대한 연구)

  • Park, Do-Min;Park, Sung-Lim;Gweon, Dae-Gab
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.3
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    • pp.684-687
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    • 1998
  • The biggest problem common on to all forms of Phase Shift Interferometer is unwrapping the phase. Simple phase unwrapping algorithms assume that every pixel is within radians of its neighbors. If this is true, any reasonable algorithm will return the correct unwrapped phase. If not, correct unwrapped phase will not be obtained. In rough surface, frequently, neighboring pixels have phase steps greater than. This paper proposes the new method which makes phase steps smaller than by sub-pixel movement.

Underwater mobile communication scheme based on the direct sequence spread spectrum transmission using Doppler estimation and its sea trial results with the pseudo-moving transmission (도플러 추정을 적용한 직접수열 대역확산 전송 기반 수중 이동통신 방법 및 가상 이동신호를 이용한 해상시험 결과)

  • Kim, Seung-Geun
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.1
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    • pp.16-29
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    • 2022
  • This paper presents a Doppler shift estimation method and signal processing schemes for Direct Sequence Spread Spectrum (DSSS) transmission to overcome the Doppler shift due to the moving of the underwater communication unit. The proposed method estimates a Doppler shift via 2 step procedures using the preamble with the two 64-length Frank sequences which has a good self-correlation characteristic and is insensitive to the Doppler shift. Furthermore, a packet of DSSS underwater mobile communication and a RAKE receiver are designed using the proposed Doppler shift estimation method. Due to the modulation scheme of the designed DSSS underwater mobile communication using Differential-Quadrature Phase Shift Keying (DQPSK) for the data symbol transmission, the RAKE receiver dose not need a phase tracking and easily makes coherent signals among the combining RAKE branches. The designed RAKE receiving scheme including the proposed Doppler shift estimation method successfully decides information data using the DSSS signal transmitted from the pseudo-moving transmitter with velocity upto about 17.5 m/s.

ZVS Phase Shift Full-Bridge Converter's Small Signal Modeling and Digital Controller Design (ZVS 위상천이 풀브리지 컨버터의 소신호 모델링 및 디지털 제어기 설계)

  • Kim, Jeong-Woo;Cho, Younghoon;Choe, Gyu-Ha
    • Proceedings of the KIPE Conference
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    • 2014.07a
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    • pp.321-322
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    • 2014
  • In this paper, a zero-voltage switching (ZVS) phase shift full-bridge converter is analyzed. The small-signal model is derived to design a digital controller. PLECS simulation shows how sampling method effects on transfer function of ZVS phase shift full-bridge converter.

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An Improved Phase Estimation Method for AM Range Measurement System (진폭 변조 거리 측정 시스템에 적용 가능한 개선된 위상 추정 기법)

  • Kim, Dae-Joong;Oh, Taek-Hwan;Hwang, Sun-Young
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.6C
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    • pp.453-461
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    • 2012
  • This paper proposes an improved phase estimation method for AM(Amplitude Modulation) range measurement system. The previous phase estimation method induces errors by Doppler shift of a moving target. The proposed method compensates phase estimation error through the ADC(Adaptive Doppler Correction) to take the Doppler shift, thus can improve distance measurement accuracy. When compared with the previous method through simulation results, the Doppler shift compensation and accuracy are improved by 94.7% and 50%, respectively. Target distance error in an acoustic tank is estimated to be 7.7cm, which confirms that the proposed method can be used to estimate the distance in the marine environment.

Review on the Determination of Frumkin, Langmuir, and Temkin Adsorption Isotherms at Electrode/Solution Interfaces Using the Phase-Shift Method and Correlation Constants

  • Chun, Jinyoung;Chun, Jang H.
    • Korean Chemical Engineering Research
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    • v.54 no.6
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    • pp.734-745
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    • 2016
  • This review article described the electrochemical Frumkin, Langmuir, and Temkin adsorption isotherms of over-potentially deposited hydrogen (OPD H) and deuterium (OPD D) for the cathodic $H_2$ and $D_2$ evolution reactions (HER, DER) at Pt, Ir, Pt-Ir alloy, Pd, Au, and Re/normal ($H_2O$) and heavy water ($D_2O$) solution interfaces. The Frumkin, Langmuir, and Temkin adsorption isotherms of intermediates (OPD H, OPD D, etc.) for sequential reactions (HER, DER, etc.) at electrode/solution interfaces are determined using the phase-shift method and correlation constants, which have been suggested and developed by Chun et al. The basic procedure of the phase-shift method, the Frumkin, Langmuir, and Temkin adsorption isotherms of OPD H and OPD D and related electrode kinetic and thermodynamic parameters, i.e., the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. potential (E) behavior (${\theta}$ vs. E), equilibrium constant (K), interaction parameter (g), standard Gibbs energy (${\Delta}G_{\theta}{^{\circ}}$) of adsorption, and rate (r) of change of ${\Delta}G_{\theta}{^{\circ}}$ with ${\theta}$ ($0{\leq}{\theta}{\leq}1$), at the interfaces are briefly interpreted and summarized. The phase-shift method and correlation constants are useful and effective techniques to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and related electrode kinetic and thermodynamic parameters (${\theta}$ vs. E, K, g, ${\Delta}G_{\theta}{^{\circ}}$, r) at electrode/solution interfaces.

A Novel Interleaving Control Scheme for Boost Converters Operating in Critical Conduction Mode

  • Yang, Xu;Ying, Yanping;Chen, Wenjie
    • Journal of Power Electronics
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    • v.10 no.2
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    • pp.132-137
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    • 2010
  • Interleaving techniques are widely used to reduce input/output ripples and to increase the power capacity of boost converters operating in critical conduction mode. Two types of phase-shift control schemes are studied in this paper, the turn-on time shifting method and the turn-off time shifting method. It is found that although the turn-off time shifting method exhibits better performance, it suffers from sub-harmonic oscillations at high input voltages. To solve this problem, an intensive quantitative analysis of the sub-harmonic oscillation phenomenon is made in this paper. Based upon that, a novel modified turn off time shifting control scheme for interleaved boost converters operating in critical conduction mode is proposed. An important advantage of this scheme is that both the master phase and the slave phase can operate stably in critical conduction mode without any oscillations in the full input voltage range. This method is implemented with a FPGA based digital PWM control platform, and tests were carried out on a two-phase interleaved boost PFC converter prototype. Experimental results demonstrated the feasibility and performance of the proposed phase-shift control scheme.

The Phase-Shift Method for the Langmuir Adsorption Isotherms at the Noble Metal (Au, Rh) Electrode Interfaces (귀금속(Au, Rh) 전극계면에서 Langmuir 흡착등온식에 관한 위상이동방법)

  • Chun, Jang H.;Jeon, Sang K.;Lee, Jae H.
    • Journal of the Korean Electrochemical Society
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    • v.6 no.2
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    • pp.119-129
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    • 2003
  • The Langmuir adsorption isotherms of the over-potentially deposited hydrogen (OPD H) fur the cathodic $H_2$ evolution reaction (HER) at the poly-Au and $Rh|0.5M\;H_2SO_4$ aqueous electrolyte interfaces have been studied using cyclic voltammetric and ac impedance techniques. The behavior of the phase shift $(0^{\circ}{\leq}{-\phi}{\leq}90^{\circ})$ for the optimum intermediate frequency corresponds well to that of the fractional surface coverage $(1{\geq}{\theta}{\geq}0)$ at the interfaces. The phase-shift profile $({-\phi}\;vs.\;E)$ for the optimum intermediate frequency, i.e., the phase-shift method, can be used as a new electrochemical method to determine the Langmuir adsorption isotherm $({\theta}\;vs.\;E)$ of the OPD H for the cathodic HER at the interfaces. At the poly-Au|0.5M $H_2SO_4$ aqueous electrolyte interface, the equilibrium constant (K) and the standard free energy $({\Delta}G_{ads})$ of the OPD H are $2.3\times10^{-6}$ and 32.2kJ/mol, respectively. At the poly-Rh|0.5M $H_2SO_4$ aqueous electrolyte interface, K and ${\Delta}G_{ads}$ of the OPD H are $4.1\times10^4\;or\;1.2\times10^{-2}$ and 19.3 or 11.0kJ/mol depending on E, respectively. In contrast to the poly-Au electrode interface, the two different Langmuir adsorption isotherms of the OPD H are observed at the poly-Rh electrode interface. The two different Langmuir adsorption isotherms of the OPD H correspond to the two different adsorption sites of the OPD H on the poly-Rh electrode surface.

Software PLL Based Speed Control of High Speed Miniature BLDC (소프트웨어 PLL 기반 소형 고속 BLDC의 속도 제어)

  • Park, Tae-Hub;Seok, Seung-Hun;Lee, Dong-Hee;Ahn, Jin-Woo
    • Proceedings of the KIEE Conference
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    • 2008.10c
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    • pp.132-135
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    • 2008
  • This paper presents a PLL(Phase Lock Loop) control method for speed control of high speed miniature BLDCM(Brushless DC Motor) using hall sensor. The Proposed PLL based speed control method uses a only phase shift between reference pulse signal according to speed reference and actual pulse signal from hall sensor. It doesn't use any speed calculation, and calculates a direct current reference from phase shift. The current reference is changed to reduce the phase shift between reference and actual pulse. So the actual speed can keep the reference speed. The proposed control scheme is very simple but effective speed control is possible.

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Single Phase-Shift Modulation with Variable-Frequency to Reduce Conduction Losses of DAB Converters (DAB 컨버터의 전도 손실 저감을 위한 가변 주파수의 단일 위상 시프트 변조기법)

  • Dao, Ngoc Dat;Lee, Dong-Choon
    • Proceedings of the KIPE Conference
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    • 2019.11a
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    • pp.124-125
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    • 2019
  • This paper proposes a novel control method to minimize conduction losses of dual active bridge (DAB) converters for on-board chargers of electric vehicles (EVs). In the control method, two variables are regulated, which are the phase-shift angle between the primary and secondary full bridges and the switching frequency. From time-domain analysis, an optimal phase-shift angle is derived to achieve the minimum RMS value of the transformer current. The proposed method was implemented for a 3.6-kW SiC-based prototype to validate its effectiveness. A high efficiency over 97.3% has been achieved for a wide output voltage range.

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