• Title, Summary, Keyword: Resonance

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Fluid-structure interaction analysis of micromechanical resonance sensor (마이크로기계 공진 센서의 유체-구조물 상호 작용 해석)

  • Kang, In-Goo;Shin, Yoon-Hyuk;Yim, Hong-Jae;Lim, Si-Hyung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.309-313
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    • 2009
  • A micromechanical resonance sensor detects the resonance frequency shift due to mass or adsorption induced surface stress change during molecular adsorption or interaction on its surface. The resonance sensor is surrounded by gas or liquid solution during operation. To study the resonance shift phenomena depending on its surrounding environment, fluid-structure interaction of the resonance sensor has been analyzed for the different fluid environment and boundary conditions using finite element analysis.

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A Wide-band Multi-layer Antenna Design using Double Resonance (이중공진을 사용한 적층기판용 광대역 안테나 설계)

  • Lee, Kook-Joo;Zhang, Mei-Shan;Lee, Jung-Aun;Han, Myeong-Woo;Kim, Moon-Il
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.2
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    • pp.431-434
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    • 2011
  • In this paper, bandwidth enhanced design of dielectric resonator antenna fabricated in multi-layer substrate is introduced. The proposed dielectric resonator antenna is operating with fundamental TE101 mode and higher-order TM111 mode. Each resonance frequency is dependent on resonator dimensions. As increasing the height of radiating aperture, the higher-order TM111 mode resonance frequency approach the fundamental TE101 mode resonance frequency and the antenna bandwidth increase by double resonance. Three different aperture height size antennas that operated at 7GHz are fabricated in FR4 multi-layer substrate. Measured 10 dB matching bandwidth is 8 percent for single resonace antenna and 18 percent for double resonance antenna.

Energy Calibration for Neutron Capture Resonance of Natural Sm by Using 46-MeV Electron Linear Accelerator

  • Lee, Jae-Hong;Lee, Sam-Yol
    • Journal of the Korean Society of Radiology
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    • v.1 no.2
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    • pp.31-35
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    • 2007
  • Energy calibration is important to identify accurate neutron capture resonance energy in the neutron TOF (Time-of-Flight) experiment. In present study, the accurate neutron capture resonance energies of natural Sm were measured by using a 46-MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University(KURRI). The BGO spectrometer were adopted for measurement the prompt capture gamma-ray of the sample. To obtain energy calibration curve, resonance energy of a gold sample used as standard resonance energy Mughabghab's data (From neutron resonance parameters data). Previous data (by Mughabghab) of natural Sm sample have been compared with the present result.

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Resonance avoidance and Safety Evaluation of Vertical Pump (입형펌프의 공진회피와 안전성 평가)

  • Jeong, Wooyoung;Song, Jindae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.698-702
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    • 2013
  • This paper considers the vertical pumps resonance and soundness. Normally large vertical pump's rotating speed is low, so the low natural mode can make a resonance on the motor and motor stand assembly. The pump resonance makes a very high vibration and trouble on the pump systems. Thus to avoid pump resonance when the pump is on the resonance region, we give the added mass method and evaluate the structure soundness by computer simulation and test on the site. Furthermore we evaluate the modal sensitivity and expect running conditions by the using ISO10814.

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Impedance Matching Based Control for the Resonance Damping of Microgrids with Multiple Grid Connected Converters

  • Tan, Shulong;Geng, Hua;Yang, Geng
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2338-2349
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    • 2016
  • This paper presents an impedance-matching-based control scheme for the harmonic resonance damping of multiple grid-connected-converters (GCCs) with LCL filters. As indicated in this paper, harmonic resonance occurs if a GCC possesses an output impedance that is not matched with the rest of the network in some specific frequency bands. It is also revealed that the resonance frequency is associated with the number of GCCs, the grid impedance and even the capacitive loads. By controlling the grid-side current instead of the converter-side current, the critical LCL filter is restricted as an internal component. Thus, the closed-loop output impedance of the GCC within the filter can be configured. The proposed scheme actively regulates the output impedance of the GCC to match the impedance of the external network, based on the detected resonance frequency. As a result, the resonance risk of multiple GCCs can be avoided, which is beneficial for the plug-and-play property of the GCCs in microgrids. Simulation and experimental results validate the effectiveness of the proposed method.

Magnetic Resonance Imaging with Intermolecular Double Quantum Coherences

  • Ahn, Sang-Doo
    • Journal of the Korean Magnetic Resonance Society
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    • v.8 no.2
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    • pp.108-114
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    • 2004
  • Recently a new method for magnetic resonance imaging based on the detection of relatively strong signal from intermolecular multiple quantum coherences (iMQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; it originates in long-range dipolar couplings that are traditionally ignored. In this paper, we present the results of experimental studies to assess the feasibility of intermolecular double quantum coherences (iDQCs) imaging in humans. We show that the iDQC images are readily observable at 4T and that they do indeed provide different contrast than appears in conventional images.

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Resonance Frequency and Bandwidth of the Negative/Positive nth Mode of a Composite Right-/Left-Handed Transmission Line

  • Kim, Seong-Jung;Lee, Jeong-Hae
    • Journal of electromagnetic engineering and science
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    • v.18 no.1
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    • pp.1-6
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    • 2018
  • In this study, the analytic expression for the positive/negative $n^{th}-Mode$ resonance frequency of an N unit cell composite right-/lefthanded (CRLH) transmission line is derived. To explain the resonance mechanism of the $n^{th}$ mode, especially for the negative mode, the current distribution of the N unit cell CRLH transmission line is investigated with a circuit simulation. Results show that both positive and negative $n^{th}$ resonance modes have n times current variations, but their phase difference is $180^{\circ}$ as expected. Moreover, the positive $n^{th}$ resonance occurs at a high frequency, whereas the negative $n^{th}$ resonance transpires at a low frequency, thus indicating that the negative resonance mode can be utilized for a small resonator. The correlation between the slope of the dispersion curve and the bandwidth is also observed. In sum, the balanced condition of the CRLH transmission line provides a broader bandwidth than the unbalanced condition.