• Title/Summary/Keyword: Method reference frequency

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Study on Measurements of the In-Plane Vibration Intensity In a Beam With a Damped End (감쇠 단을 갖는 보의 면내 진동인텐시티 측정에 관한 연구)

  • Kim Chang-Yeol;Kil Hyun-Gwon;Hong Suk-Yoon
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.7
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    • pp.371-378
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    • 2005
  • The objective or this paper is to measure the in-plane vibration intensity of a beam with a damped end that means the magnitude and direction of vibration power. Three experimental methods have been implemented to measure the in-plane vibration intensity over the beam. The first method is the accelerometer array method using two accelerometers. The second method is the frequency response function method using the only one accelerometer. The third method is the reference accelerometer method using a fixed reference accelerometer and another moving accelerometer. Those methods have been used to measure the spatial distribution of in-plane vibration intensity over the beam. The results obtained with those methods have been compared with each other. The results have been compared with an input power. It showed that the frequency response function method and the reference accelerometer method as well as the accelerometer array method can be effectively used to measure the in-plane vibration intensity in beams.

Modal Analysis of Rotating Beam Structures Having Complex Configurations Employing Multi-Reference Frames

  • Kim, Jung-Min;Yoo, Hong-Hee
    • Journal of Mechanical Science and Technology
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    • v.20 no.1
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    • pp.66-75
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    • 2006
  • A modeling method for the modal analysis of rotating beam structures having complex configurations employing multi-reference frames is presented in the present study. In most structural analysis methods, single reference frame is employed for the modal analysis. For simple structures such as single beam or single plate, the method of employing single reference frame usually provides rapidly converging accurate results. However, for general structures having complex configurations, such a method provides slowly converging, and often erroneous, results. In the present study, the effects of employing multi-reference frames on the convergence and the accuracy of the modal analysis of rotating beam structures having complex configurations are investigated.

A method for eliminating periodic interference by sampling frequency control of discrete-time notch filter (이산-시간 노치 여파기의 표본화 주파수 제어에 의한 주기성 간섭의 제거방법)

  • 염동홍;안수길
    • 전기의세계
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    • v.31 no.6
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    • pp.450-456
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    • 1982
  • This paper proposes a new method for eliminating periodic interference corrupting a signal. The method proposed herein uses a variable notch filter by sampling frequency control to eliminate the interference. This method is applicable when an auxiliary reference input is available containing the interference alone. The sampling frequency is determined by the fundamental frequency of the periodic interference. Also, this paper proposes a design procedure so that it can be easily applied.

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Experimental Structural Dynamic Modification of Fixture for Vibration Testing (진동시험용 치구의 실험적 구조변경 설계)

  • 정의봉;오영세;김준엽
    • Journal of KSNVE
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    • v.8 no.1
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    • pp.180-186
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    • 1998
  • Vibration test fixture is used in random vibration control testing. The specified reference spectrum should be transmitted equally to the specimen attachment points on the fixture. In most practical cases, however, spectrum at each of specimen attachment points may be quite different from the specified reference spectrum because of the dynamic characteristics of vibration test fixture. This paper proposes the method of experimental dynamic modification of fixture system for vibration test so that the reference spectrum can be transmitted to the specimen attachment points without distortion. The stiffness of mounts of specimen and the thickness of fixture are considered as design variables. The frequency response functions of specimen used for input data are obtained from vibration testing, and the frequency response functions of fixture are obtained from finite element modeling. The sensitivities of frequency response functions at specimen attachment points to the mount stiffness are derived from synthesis method of transfer function. And the sensitivities to the thickness of fixture are also derived from finite element modeling. The presented method is verified by computer simulation and vibration testing.

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Load Frequency Control by Optimal Linear Tracking (최적선형 추적법에 의한 부하-주파수제어)

  • 김훈기;곽노홍;문영현
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.38 no.2
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    • pp.83-92
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    • 1989
  • This paper presents a load frequency control by optimal linear tracking, which can be well adapted to practical power systems with successive load disturbances. Conventional Load Frequency Controls (LEC's) have a feedback control scheme of the state error deviated from the post-disturbance steady state. This requires the modification of reference everytime the system encounters load changes. In this study, a new feedback scheme of LEC is developed by using the optimal linear tracking method with a fixed reference. As a result, the proposed LFC, which requires no reference modification, can be efficiently applied to power systems with successive disturbances such as load changes due to the on-off operations of reclosers or feeder switches. Another feature of the proposed LFC is that it adopts an algorithm to calculate an optimal post-fault steady state with the consideration of control input changes. The proposed LFC has been tested for a 2-area power system, which shows that it can be well adapted to successive load disturbances with good frequency response.

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Vibration Analysis of Rotating Structures Employing Multi-Reference Frames (다중 기준틀을 사용한 회전 구조물의 진동해석)

  • 김정민;유홍희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.814-819
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    • 2004
  • In this paper, a modeling method for the vibration analysis of rotating structures employing multi-reference frames is presented. The geometric stiffening effect that results from centrifugal inertia force is considered. In most previous studies single reference frame has been employed for the analysis. In the present study, a modeling method employing multi-reference frames is presented, and the effects of employing multi-reference frames on the analysis accuracy are investigated through solving numerical examples.

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Vibration Analysis of Rotating Structures Employing Multi-reference Frames (다중 기준틀을 사용한 회전 구조물의 진동해석)

  • 김정민;유홍희
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.10
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    • pp.983-989
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    • 2004
  • In this paper, a modeling method for the vibration analysis of rotating structures employing multi-reference frames is presented. The geometric stiffening effect that results from centrifugal inertia force is considered. In most previous studies single reference frame has been employed for the analysis. In the present study, a modeling method employing multi-reference frames is presented, and the effects of employing multi-reference frames on the analysis accuracy are investigated through solving numerical examples.

A New Synchronous Reference Frame-Based Method for Single-Phase Shunt Active Power Filters

  • Monfared, Mohammad;Golestan, Saeed;Guerrero, Josep M.
    • Journal of Power Electronics
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    • v.13 no.4
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    • pp.692-700
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    • 2013
  • This paper discusses the design of a novel synchronous reference frame (SRF) method that can extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous SRF studies, the proposed method has an innovative feature that does not require a fictitious current signal. Other key features of the proposed strategy include frequency-independent operation, accurate reference current extraction, and relatively fast transient response. The effectiveness of the proposed method is investigated by conducting a detailed mathematical analysis. Results of the analysis confirm the superior performance of the suggested approach. Theoretical evaluations are confirmed by the experimental results.

Estimation of Fault Location on a Power Line using the Time-Frequency Domain Reflectometry (절연전선 결함 위치 추정에 대한 시간-주파수 영역 반사파 계측법의 적용)

  • Doo, Seung-Ho;Kwak, Ki-Seok;Park, Jin-Bae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.2
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    • pp.268-275
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    • 2008
  • In this paper, we introduce a new method for detecting and estimating faults on a power line using the time-frequency domain reflectometry system. The system rests upon time-frequency signal analysis and uses a chirp signal which is multiplied by Gaussian envelope. The chirp signal is used as a reference signal, and we can get the reflected signal from a fault on a wire. To detect and estimate faults, we analyze the reflected signal by Wigner time-frequency distribution function and normalized time-frequency cross correlation function. In this paper we design an optimal reference signal for power line and implement a system for estimating fault distance on a power line with the TFDR implemented by PXI equipments. This approach is verified by some experiments with HIV 2.25mm power lines.

The Effect of Internal Tetramethylsilane Reference in Determination of $^{13}C$ NMR Chemical Shifts ($^{13}C$ NMR 화학 Shift 측정에 미치는 TMS의 거동)

  • Youm, Jeong-Rok
    • YAKHAK HOEJI
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    • v.33 no.3
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    • pp.203-205
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    • 1989
  • A method is presented for calculating the $^{13}C$ chemical shifts produced in liquid solution by referenced relative to RF frequency. The method is useful to get the real variations of chemical shifts in magnetic field by eliminating the affects of the variation of a reference substance.

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