• Title/Summary/Keyword: power transducers

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DESIGN OF A VIBRATION AND STRESS MEASUREMENT SYSTEM FOR AN ADVANCED POWER REACTOR 1400 REACTOR VESSEL INTERNALS COMPREHENSIVE VIBRATION ASSESSMENT PROGRAM

  • Ko, Do-Young;Kim, Kyu-Hyung
    • Nuclear Engineering and Technology
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    • v.45 no.2
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    • pp.249-256
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    • 2013
  • In accordance with the US Nuclear Regulatory Commission (US NRC), Regulatory Guide 1.20, the reactor vessel internals comprehensive vibration assessment program (RVI CVAP) has been developed for an Advanced Power Reactor 1400 (APR1400). The purpose of the RVI CVAP is to verify the structural integrity of the reactor internals to flow-induced loads prior to commercial operation. The APR1400 RVI CVAP consists of four programs (analysis, measurement, inspection, and assessment). Thoughtful preparation is essential to the measurement program, because data acquisition must be performed only once. The optimized design of a vibration and stress measurement system for the RVI CVAP is essential to verify the integrity of the APR1400 RVI. We successfully designed a vibration and stress measurement system for the APR1400 RVI CVAP based on the design materials, the hydraulic and structural analysis results, and performance tests of transducers in an extreme environment. The measurement system designed in this paper will be utilized for the APR1400 RVI CVAP as part of the first construction project in Korea.

Classification of Acoustic Emission Signals from Fatigue Crack Propagation in 2024 and 5052 Aluminum Alloys

  • Nam, Ki-Woo;Moon, Chang-Kwon
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.4 no.1
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    • pp.51-55
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    • 2001
  • The characteristics of elastic waves emanating from crack initiation in 2024 and 5052 aluminum alloys subject to static and fatigue loading are investigated through laboratory experiments. The objective of the study is to determine difference in the properties of the signals generated from static and fatigue tests and also to examine if the sources of the waves could be identified from the temporal and spectral characteristics of the acoustic emission (AE) waveforms. The signals are recoded using non-resonant, flat, broadband transducers attached to the surface of the alloy specimens. The time dependence and power spectra of the signals recorded during the tests were examined and classified according to their special features. Three distinct types of signals were observed. The waveforms and their power spectra were found to be dependent on the material and the type of fracture associated with the signals. Analysis of the waveforms indicated that some signals could be attributed to plastic deformation associated with static tests. The potential application of the approach in health monitoring of aging aircraft structures using a network of surface mounted broadband sensors is discussed.

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Wideband and 2D vibration energy harvester using multiple magnetoelectric transducers

  • Yang, Jin;Yu, Qiangmo;Zhao, Jiangxin;Zhao, Nian;Wen, Yumei;Li, Ping
    • Smart Structures and Systems
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    • v.16 no.4
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    • pp.579-591
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    • 2015
  • This paper investigates a magnetoelectric (ME) vibration energy harvester that can scavenge energy in arbitrary directions in a plane as well as wide working bandwidth. In this harvester, a circular cross-section cantilever rod is adopted to extract the external vibration energy due to the capability of it's free end oscillating in arbitrary in-plane directions. And permanent magnets are fixed to the free end of the cantilever rod, causing it to experience a non-linear force as it moves with respect to stationary ME transducers and magnets. The magnetically coupled cantilever rod exhibits a nonlinear and two-mode motion, and responds to vibration over a much broader frequency range than a standard cantilever. The effects of the magnetic field distribution and the magnetic force on the harvester's voltage response are investigated with the aim to obtain the optimal vibration energy harvesting performances. A prototype harvester was fabricated and experimentally tested, and the experimental results verified that the harvester can extract energy from arbitrary in-plane directions, and had maximum bandwidth of 5.5 Hz, and output power of 0.13 mW at an acceleration of 0.6 g (with $g=9.8ms^{-2}$).

A Resonant-type Step-up DC/DC Converters with Piezoelectric Transducer (압전 트랜스듀서를 이용한 승압형 공진형 직류-직류 컨버터)

  • Park, Joung-Hu;Seo, Gab-Su;Cho, Bo-Hyung;Yi, Kyung-Pyo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.14 no.5
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    • pp.343-354
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    • 2009
  • In this paper, a magnetic-less dc-dc switching converter realizing an integrable power conversion system is described. Instead of magnetic devices, the inductive impedance range of piezoelectric transducers is utilized to store and resonate the energy for soft-switching. Piezoelectric devices have no windings and deliver the power by the electrodes, which lead to mass product through semiconductor-manufacturing process. This paper presents a resonant-type step-up dc-dc power converter employing a disk-type piezoelectric transducer, analyzing the operation principles and the frequency control characteristics. Also, a topology extension of the single stage converter into cascaded multi-stage is presented and analyzed with the operation principles and control characteristics. For verification of the analysis, a 10W output dc-dc power converter hardware was implemented. The hardware experiments shows a good frequency control and power efficiency greater than 96% in the single stage. A hardware prototype of the extended multi-stage one was also realized and tested. The results shows that the converter has the same frequency control performance and high efficiency such as 93%.

A Nonlinear Filtered-X LMS Algorithm for the Nonlinear Compensation of the Secondary Path in Active Noise Control (능동 소음 제어 시스템의 2차 경로 비선형 특성을 보상하기 위한 적응 비선형 Filtered-X Least Mean Square (FX-LMS) 알고리듬)

  • Jeong, I.S.;Kim, D.H.;Nam, S.W.
    • Proceedings of the KIEE Conference
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    • 2004.11c
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    • pp.565-567
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    • 2004
  • In active noise control (ANC) systems, the convergence behavior of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path (e.g., in the power amplifiers, loudspeakers, transducers, etc.), which may lead to degradation of the error-reduction performance of the ANC systems. In this paper, a stable FXLMS algorithm with fast convergence is proposed to compensate for undesirable nonlinear distortions in the secondary-path of ANC systems by employing the Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better convergence behavior In the nonlinear ANC systems than the conventional FXLMS.

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Active-Sensing Lamb Wave Propagations for Damage Identification in Honeycomb Aluminum Panels

  • Flynn, Eric B.;Swartz, R.Andrew;Backman, Daniel E.;Park, Gyu-Hae;Farrar, Charles R.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.29 no.4
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    • pp.269-282
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    • 2009
  • This paper presents a novel approach for Lamb wave based structural health monitoring(SHM) in honeycomb aluminum panels. In this study, a suite of three signal processing algorithms are employed to improve the damage detection capability. The signal processing algorithms used include wavelet attenuation, correlation coefficients of power density spectra, and triangulation of reflected waves. Piezoelectric transducers are utilized as both sensors and actuators for Lamb wave propagation. These SHM algorithms are built into a MatLab interface that integrates and automates the hardware and software operations and displays the results for each algorithm to the analyst for side by side comparison. The effectiveness of each of these signal processing algorithms for SHM in honeycomb aluminum panels under a variety of damage conditions is then demonstrated.

Simulation of a piezoelectric flextentional sonar transducer using a coupled FE-BEM (결합형 유한요소-경계요소 기법을 사용한 압전체 유연형 쏘나 변환기 시뮬레이션)

  • Jarng, Soon-Suck
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.05a
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    • pp.307-312
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    • 1999
  • A piezoelectric flextentional sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state displacement modes, underwater directivity patterns. It is shown that the present barrel-stave sonar transducer of the piezoelectric material produces flextentional displacements which could be related with higher output power, lower quality factor and more omnidirectional beam pattern than other types of sonar transducers.

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Nonlinearity Compensation in the Secondary Path of Active Noise Control Systems Using An Inverse Adaptive Volterra Filtering (역 적응 볼테라 필터링을 이용한 능동 소음 제어 시스템의 2차 경로 비선형 특성 적응 보상)

  • Jeong I.S.;Lee I.H.;Nam S.W.
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.12
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    • pp.827-833
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    • 2004
  • In active noise control (ANC) systems, the error-reduction performance of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path such as in the power amplifiers, loudspeakers and transducers. In this paper, a nonlinear FXLMS algorithm with high error-reduction performance is proposed to compensate for undesirable nonlinearities in the secondary-path of ANC systems by employing the inverse Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better nonlinearity compensation performance for the ANC systems with a nonlinear secondary path than the conventional FXLMS.

Gradual pipe wall thinning diagnosis through the variation of dispersion characteristics of SH waves (SH파 분산특성 변화를 이용한 배관 점진감육 진단 기법)

  • Cho, Seung-Hyun;Kwon, Hyu-Sang;Ahn, Bong-Young;Lee, Seung-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.258-259
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    • 2009
  • Pipe wall thinning is one of severe problems on structural safety in nuclear power plants. A guided wave can be a proper tool for the fast evaluation or monitoring. As for gradual wall thinnings, however, low sensitivity caused by the low reflection coefficient limits the use of the guided wave. In this work, instead of the guided wave reflection at the wall thinning, the variation of dispersion characteristics is concerned. SH waves were employed due to several advantages and the magnetostrictive patch transducers were used for the excitation and sensing of the SH waves. The proposed method were verified with some experiments and showed the feasibility as an effective tool for the inspection of gradual wall thinning.

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Acoustic Analysis of High-Frequency Ultrasonic Cleaner

  • Choi, Sunghoon;Kim, Jin Oh;Kim, Yong-Hoon
    • The Journal of the Acoustical Society of Korea
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    • v.16 no.1E
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    • pp.49-56
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    • 1997
  • Ultrasonic cleaning at high frequency around 1 MHz, called megasonic cleaning, is commonly used to remove particles less than 1 ㎛ by generating high frequency accelerations on the cleaning objects. Cleaning is performed in an ultrasonically-excited liquid contained in a double-structured container. Ultrasonic waves generated by piezoelectric transducers propagate in the outer container and are transmitted through the inner container. The bottom of the inner container is inclined to make oblique incidence of the ultrasonic wave in order to raise the efficiency of the transmission through the bottom plate. This work deals with the efficiency of the transmission, which directly affects the cleaning performance. The transmission characteristics of the ultrasonic wave in the megasonic cleaner have been obtained analytically and numerically for the variations of some parameters, such as the thickness and inclined angle of the bottom plate of the inner container and the chemical ratio and temperature of the cleaning liquid. The calculated results have yielded the optimum cleaning condition in terms of the sound power transmitted into the cleaning liquid.

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