• Title, Summary, Keyword: Resonance

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Adaptive Suppression of Mechanical Resonance in High-Density Disk Drives (고밀도 디스크 드라이브의 적응형 공진 보상 알고리즘)

  • 강창익;김창환
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.9
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    • pp.679-691
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    • 2003
  • The band-width of disk drive servo system is rapidly increasing for the robustness to external disturbance as the track density is increasing. The increase of the band-width may cause mechanical resonance of an actuator. In disk drive servo system, a notch filter is usually used to suppress the mechanical resonance of the actuator. However, the resonance frequency differs from drive to drive because of manufacturing tolerance and varies with temperature even within a single drive. The variation of resonance frequency degrades the suppression performance of the notch filter. In this paper, we present an adaptive digital notch filter that identifies the resonance frequency of the disk drive servo actutaor precisely and adjusts automatically its center frequency. For this, we design an adaptive FIR digital filter for the estimation of the resonance frequency. The estimation filter identifies the resonance frequency adaptively using the output signal generated from the servo system, which is excited with an excitation signal including all the expected resonance frequency components. We prove mathematically the convergence of the resonance frequency estimation filter. Furthermore, in order to demonstrate the practical use of our work, we present some experimental results using a commercially available disk drive.

Resonance Characteristics Analysis of Grid-connected Inverter Systems based on Sensitivity Theory

  • Wu, Jian;Han, Wanqin;Chen, Tao;Zhao, Jiaqi;Li, Binbin;Xu, Dianguo
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.746-756
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    • 2018
  • Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

Synthesis and Characterization of a Receptor-Targeting Contrast Agent

  • Yang, Taegyun;Park, Ji-Hyung;Lee, Seung-Cheol;Kim, Cheol-Su;Cho, Jee-Hyun;Lee, Chul-Hyun;Cheong, Chae-Joon
    • Journal of the Korean Magnetic Resonance Society
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    • v.7 no.1
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    • pp.46-54
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    • 2003
  • We synthesized a contrast agent for MRI that is capable of binding to the ABP-1 receptor and enhancing the contrast of the targeted cells. We used a lysine dendrimer (G=3)DTPA[Gd] as the contrast agent and synthesized a biotinylated polyclonal antibody for ABP-1 as the first antibody. Lysine dendrimers were prepared using the solid phase peptide synthesis method.$^3$ Amino-terminated lysine dendrimers were then coupled to DTPA using the anhydride method. Gd was complexed with the DTPA-lysine dendrimer in an acidic solution of 3 eq GdCl$_3$ to one of DTPA. The lysine dendrimer-DTPA[Gd] and avidin were conjugated in MES solution, pH 6.0, using EDC as the coupling reagent. The biotin-avidin system was used to link the polyclonal antibody and contrast agent. K562 cells were used for imaging.

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A Study on the Optimal Span Length Selection of Conventional Railway Bridges considering Resonance Suppression (공진소멸 현상을 이용한 기존선 철도교량의 지간 최적화를 위한 연구)

  • Kim Sungil;Chung Wonseok;Choi Eunsoo
    • Journal of the Korean Society for Railway
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    • v.8 no.2
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    • pp.137-144
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    • 2005
  • The possibility of resonance exists always in railway bridges unlike highway bridges because railway bridges are loaded repeatedly by specific trains which has equidistant wheel loads. Resonance phenomenon of the bridge can be broken out when exciting frequencies by tram determined from the speed and effective beating internal coincides with natural frequencies of the bridge Excessive fluctuations of dynamic displacements and accelerations by resonance cause unpleasant passenger comfort and instability of railway structures. On the other hand, resonance suppression phenomenon that all the previous loads which pass through the bridge sum to zero can be occurred. In case we apply this resonance suppression properly, design of stable railway bridge from dynamics point of view can be made. In the present study, most dominant beating internal of conventional trams will be find. A(ter that. specific span length of the bridge which derives resonance suppression can be selected for railway bridges which accomplishes superior dynamic behavior.

Non-Lorentzian Resonance Due to the Detuning in One-Color Two-Photon Photodissociation

  • Lee, Seong Yul
    • Bulletin of the Korean Chemical Society
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    • v.21 no.7
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    • pp.712-714
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    • 2000
  • Non-Lorentyian resonance is predicted to occur in two-photon photoabsorption processes due to the detuning off the intermediate levels. This type of non-Lorentzian resonance is distinct from the asymmetric resonance resulting from the effects of q uantum interference between competing indistinguishable dynamic pathways. The product distributions are shown to be constant near this type of resonance.

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HIGH RESOLUTION IMAGING IN 37 MRI SYSTEM

  • Park, Jeong-Il;Choi, Kim-S.;Choe, Bo-Young;Suh, Tae-Suk;Lee, Hyoung-Koo;Shin, Kyung-Sub;Lee, Heung-Kyu
    • Proceedings of the Korean Society of Medical Physics Conference
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    • pp.423-424
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    • 1999
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