• 제목/요약/키워드: amplitude field

검색결과 636건 처리시간 0.026초

SIL 응용 광 기록계에서 발생하는 위상 및 진폭 Apodization 해석 (Analysis on Phase and Amplitude Apodization in SIL Based Near-Field Recording Optics)

  • 김완진;최현;송태선;박노철;박영필
    • 정보저장시스템학회:학술대회논문집
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    • 정보저장시스템학회 2005년도 추계학술대회 논문집
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    • pp.14-15
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    • 2005
  • In near-field recording (NFR) optics using solid immersion lens (SIL), near-field air gap induces unwanted spherical aberration, defocus and astigmatism. This phenomenon can be explained with the apodization of phase and amplitude between each linearly polarized light. In this paper, we analyzed the effect of phase and amplitude apodization with the fundamental multiple beam interference theory, and we compared resultant diffracted patterns on the image plane for the Si-disk first surface media structure and cover-layer incident media structure.

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The study of thick cell gap on the alignment of a ferroelectric liquid crystal cell

  • Wu, Jin-Jei;Wu, Po-Chang;Sie, Fu-Cheng
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.862-863
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    • 2006
  • According to the experiment results, the alignment of FLC cell can become more uniform at thick cell gap by adjusting the amplitude of the aligned AC electric field which is applying to the FLC cell during $N^{\ast}-SmC^{\ast}$ phase transition. If the amplitude of AC electric field is high enough, the FLC molecules forced with the amplitude and aligned to a particular direction.

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2차원 경계요소법에 의한 초음파 산란음장의 해석과 응용 (Analysis of Ultrasonic Scattering Fields by 2-D Boundary Element Method and Its Application)

  • 정현조
    • 대한기계학회논문집A
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    • 제29권11호
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    • pp.1439-1444
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    • 2005
  • A two-dimensional boundary element method was used for the scattering analysis of side-drilled hole(SDH). The far-field scattering amplitude was calculated for shear vertical(SV) wave, and their frequency and time-domain results were presented. The time-domain scattering amplitude showed the directly reflected wave from the SDH leading edge as well as the creeping wave. In an immersion, pulse-echo testing, two measurement models were introduced to predict the response from SDHs. The 2-D boundary element scattering amplitude was converted to the 3-D amplitude to be used in the measurement model. The receiver voltage was calculated fer SV wave incidence at 45$^{\circ}C$ on the 1 m diameter SDH, and the result was compared with experiment.

Three-Dimensional Magnetohydrodynamic Simulations of Nonlinear Field Line Resonances

  • Kim, Kyung-Im;Lee, Dong-Hun;Ryu, Dong-Su
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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    • pp.39.2-39.2
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    • 2010
  • Field line resonances (FLRs) observed in the magnetosphere often have the amplitude of a few nT, which indicates that dB/B roughly satisfies ~0.01. It is well known that the FLRs are excited by compressional waves via mode conversion, but there has been no apparent criterion on the maximum amplitude in the regime of linear approximations. Such limited range of amplitude should be understood by including nonlinear saturation of FLRs, which has not been examined until now. In this study, using a three-dimensional magnetohydrodynamic (MHD) simulation code, we examine the evolution of nonlinear field line resonances (FLRs) in the cold plasmas. The MHD code used in this study allows a full nonlinear description and enables us to study the maximum amplitude of FLRs. When the disturbance is sufficiently small, it is shown that linear properties of MHD wave coupling are well reproduced. In order to examine a nonlinear excitation of FLRs, it is shown how these FLRs become saturated as the initial magnitude of disturbances is assumed to increase. Our results suggest that the maximum amplitude of FLRs become saturated at the level of the same order of dB/B as in observations. In addition, we discuss the role of both linear terms and nonlinear terms in the MHD wave equations.

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신경조직 재활치료를 위한Crossing High-Amplitude Magneto-Therapy 자기신경 시스템의 설계 및 제작에 관한 연구 (Research about design and manufacture of Crossing High-Amplitude Magneto-Therapy own nerve system for nervous tissue rehalibitation treatment)

  • 김휘영
    • 한국컴퓨터산업학회논문지
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    • 제7권3호
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    • pp.263-270
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    • 2006
  • 자계신경 자극치료는 다른 분야에 비해 많이 낙후된 실정이다. 특히, 자기장(MF)의 성공적인 의료도입이 Avicenna의 연구에서 오래전에 언급되었고, 최근에 의학 magnetology 발달의 시대로 생각될 수 있다. 이러한 발달은 공학자와 생물학자 그리고 임상의의 접합부분 노력을 통하여 이루어지고 있으며, 새로운 장비들과 BT기술은 꾸준히 발전되고 있다. 자계신경 자극치료분야는 CMF, VMF, PMF분야 등이 대표적이나 본 연구에서는 HPMT기술인 장파 high-amplitude(전통적인 magneto-therapy의 크게 대단한 강렬) 짧은시간 치료용 시스템을 각 기능별로 설계하고 제작하여 특성을 비교분석 하였다.

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Amplitude dependency of damping of tall structures by the random decrement technique

  • Xu, An;Xie, Zhuangning;Gu, Ming;Wu, Jiurong
    • Wind and Structures
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    • 제21권2호
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    • pp.159-182
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    • 2015
  • This study focuses on the amplitude dependency of damping of tall structures by the random decrement technique (RDT). Many researchers have adopted RDT to establish the amplitude dependency of damping ratios in super-tall buildings under strong wind loads. In this study, a series of simulated examples were analyzed to examine the reliability of this method. Results show that damping ratios increase as vibration amplitudes increase in several cases; however, the damping ratios in the simulated signals were preset as constants. This finding reveals that this method and the derived amplitude-dependent damping ratio characteristics are unreliable. Moreover, this method would obviously yield misleading results if the simulated signals contain Gaussian white noise. Full-scale measurements on a super-tall building were conducted during four typhoons, and the recorded data were analyzed to observe the amplitude dependency of damping ratio. Relatively wide scatter is observed in the resulting damping ratios, and the damping ratios do not appear to have an obvious nonlinear relationship with vibration amplitude. Numerical simulation and field measurement results indicate that the widely-used method for establishing the amplitude-dependent damping characteristics of super-tall buildings and the conclusions derived from it might be questionable at the least. More field-measured data must be collected under strong wind loads, and the damping characteristics of super-tall buildings should be investigated further.

Design of Low Field RF Coil for Open MRI System by Electric Dipole Radiation

  • 김경락;양형진;오창현
    • 대한자기공명의과학회:학술대회논문집
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    • 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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    • pp.174-174
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    • 2001
  • Purpose: Dimensions of body RF coil composed of 4 rectangular loops for low field open MRI hav been optimized. The design result shows the field inhomogeneity of B1 field below 1.5 dB in the 25 cm DSV can be achieved. Method: Our low field RF coil is composed of 4 rectangular strip loops that assumed to b located at both the bottom and top sides of permanent magnet. All the loops have identica dimensions and current amplitude. First, the inductance of a loop is calculated. Second, the current distribution on the coil strip is calculated by using finite difference time doma method (FDTD). It takes as much as 4 days in FDTD simulation for low frequency RF field That's why the electrical dipole radiation method is used for simulation. With the curren distribution obtained using the FDTD simulation, for various dimensional parameters th magnetic field has been calculated by electric dipole radiation method, where the curren elements are regarded as electric dipole radiation sources. The field pattern from electri dipole radiation is almost same as that from FDTD simulation. Also, it is same as that fro the result using the Viot-Savart equation, for far tone radiation term becomes zero and th Bl field amplitude of near one radiation is the same as the B field due to static current The field homogeneity is calculated in the 25 cm BSV.

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맥동류에 놓인 구로부터의 열전달 (Heat Transfer from a Sphere in Fluctuating Flow)

  • 권영필;이계철
    • 대한설비공학회지:설비저널
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    • 제16권2호
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    • pp.185-193
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    • 1987
  • The heat transfer characteristics from a solid sphere in a fluctuating air flow is simulated numerically in the range of the Reynolds numbers, $1\;{\leqslant}\;Re\;{\leqslant}\;40.$ Such a situation may be encountered in forced convection from a heated spherical particle in a sound field or oscillat-ing flow. The amplitude and phase delay in the heat transfer response to the flow oscillation are computed for a small amplitude flow. The instantaneous response of heat transfer is simulated for the large amplitude oscillation and compared with the quasi-steady response. The effect of the oscillation on the time - mean value in the local and overall heat transfer rate is discussed along with the change in the flow .field.

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근조직 재활치료를 위한 자계신경 자극시스템의 설계 및 구현 (Research about design and manufacture of Crossing High-Amplitude Magneto-Therapy own nerve system for Muscuoskeltal tissue rehalibitation treatment)

  • 김휘영
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2006년도 하계종합학술대회
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    • pp.855-856
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    • 2006
  • Magnetic nerve stimulation treatment is much backward real condition than other field. Specially, successful medical treatment introduction of magnetic field (MF) can was refered long ago in Avicenna's work, and is thought as age of medicine magnetology development recently. These development is achieved through biologist and biophysicist and clinician's joint effort, but, new mountings and relationship air tassel are developed steadily. Magnetic nerve stimulation treatment field designs treatment system by each function during long wave high-amplitude (traditional magneto therapy of greatly great that strong that) short time that CMF, VMF, PMF field etc. are representative but are HPMT technology in this research and manufacture and special quality did comparative analysis.

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고속철도 유리애자 파손원인을 위한 현장 진동 연구 (A Study on Field Vibration for Fault Cause Analysis of Glass Insulator on High-speed Railway)

  • 김영석;송길목;방선배;김선구;류영태
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 Techno-Fair 및 합동춘계학술대회 논문집 전기물성,응용부문
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    • pp.189-190
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    • 2008
  • This study was investigated a possibility of fault of glass insulator due to vibration on high-speed railway. The proper vibration of 1-glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The proper vibration of strut tube insulator was lowest 170Hz, highest 1.5kHz. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. The surface vibration(V3) amplitude of strut tube insulator was biggest. From the FFT analysis of viaduct and open route, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in comparison with the proper vibration of strut tube insulator, the resonance was not observed. Although the amplitude of insulator is high, the possibility of fault is low because the glass insulator deterioration by the accumulation of vibration do not happen.

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