• Title/Summary/Keyword: Travelling Wave

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Digital Active Noise Control System Used Inverse Model (역모델을 이용한 디지털 능동 소음제어 시스템)

  • 정찬수;이강욱;정양응
    • The Journal of the Acoustical Society of Korea
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    • v.11 no.1E
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    • pp.56-63
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    • 1992
  • The poblem of active oise control has been analysed using a adaptive signal processing technique. In this methods, the adaptive signal processor or model predicts the primary sound wave travelling along the acoustic plant and generates the secondary source 180° out of phase which attempts to attempts to attenuate the undesired noise by destructive interference. In the solutions presented here, acoustic propagation delay is considered as a part of the model which used the FIR filter. The effects of error path and auxiliary path transfer functioin are anayzed and a new on=-line technique for error path modeling, adaptive delayed inverse modeling is presented. In this study, using these new concepts, our system can more reduce the noise level in duct to 5dB-15dB than only using LMS algorithm system.

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Design and Analysis of a L shape two touch point ultrasonic rotary motor (L형 2타점 회전모터의 설계와 해석)

  • Kim, Sung-Hyun;Park, Tae-Gone
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.85-88
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    • 2004
  • The piezoelectric ceramic is attached between 'L' type guide and 'L' type stator, This motor has rotary motion which is operated by longitudinal and bending mode. The basic structure of the two kinds of type motor that called one stator motor, two stator motor is same but we suggested a few parameters for considering their stator design and characteristics. As a result, the two stator type motor is much more useful than one stator type motor for hi-direction rotation.

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The Ultimate Pattern of Shock-Vortex Interaction

  • Chang, Keun-Shik;Barik, Hrushikesh;Chang, Se-Myong
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.337-339
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    • 2008
  • As a shock impinges into a vortex of variable strength, complex shock diffraction can occur. Since a vortex has a fixed rotating direction, the shock wave travelling in one direction creates strong asymmetry in the vortex flow field. The process is that first the shock is divided into two parts by the vortex. One part is moving in the adverse direction opposite to the vortex flow which is captured by the vortex center. The other part is moving in the favorable direction, namely, in the direction same as the vortex flow; it is swung around the vortex, accelerating the vortex flow. In this paper we have investigated numerically using ENO scheme how and why the shock-vortex interaction patterns appear so different for different parametric values. Conclusion is that there are three different types of shock-vortex interaction depending on two related parameters: shock Mach number and vortex Mach number. We present a parameter map by which we can discern what type of interaction pattern appears as a shock impinges into a vortex.

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APPLICATIONS OF THE WEIGHTED SCHEME FOR GNLS EQUATIONS IN SOLVING SOLITON SOLUTIONS

  • Zhang, Tiande;Cao, Qingjie;Price, G.W.;Djidjeli, K.;Twizell, E.H.
    • Journal of applied mathematics & informatics
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    • v.5 no.3
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    • pp.615-632
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    • 1998
  • Soliton solutions of a class of generalized nonlinear evo-lution equations are discussed analytically and numerically which is achieved using a travelling wave method to formulate one-soliton solution and the finite difference method to the numerical dolutions and the interactions between the solitons for the generalized nonlinear Schrodinger equations. The characteristic behavior of the nonlinear-ity admitted in the system has been investigated and the soliton state of the system in the limit of $\alpha\;\longrightarrow\;0$ and $\alpha\;\longrightarrow\;\infty$ has been studied. The results presented show that soliton phenomena are character-istics associated with the nonlinearities of the dynamical systems.

The Ultimate Pattern of Shock-Vortex Interaction

  • Chang, Keun-Shik;Barik, Hrushikesh;Chang, Se-Myong
    • 한국전산유체공학회:학술대회논문집
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    • 2008.10a
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    • pp.337-339
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    • 2008
  • Abstract: As a shock impinges into a vortex of variable strength, complex shock diffraction can occur. Since a vortex has a fixed rotating direction, the shock wave travelling in one direction creates strong asymmetry in the vortex flow field. The process is that first the shock is divided into two parts by the vortex. One part is moving in the adverse direction opposite to the vortex flow which is captured by the vortex center. The other part is moving in the favorable direction, namely, in the direction same as the vortex flow; it is swung around the vortex, accelerating the vortex flow. In this paper we have investigated numerically using ENO scheme how and why the shock-vortex interaction patterns appear so different for different parametric values. Conclusion is that there are three different types of shock-vortex interaction depending on two related parameters: shock Mach number and vortex Mach number. We present a parameter map by which we can discern what type of interaction pattern appears as a shock impinges into a vortex.

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A Study on the Vibration of an Annular Piezoelectric Motor Stator (압전 모터 스테이터의 진동 해석)

  • 최종운;송오섭
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 1999.11a
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    • pp.15-21
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    • 1999
  • This study investigates the free and forced vibration characteristics of an annular piezoelectric motor stator constructed of two piezoelectric material layers and one stainless steel layer. The annular piezoelectric motor stator is subjected to a travelling load produced by piezo drive electrical voltage input to the two piezoelectric layers. The stator is modeled as an annular laminated plate based on the classical plate theory and the governing equations are derived via Hamilton's variational principle. Variation of the free vibration characteristics as a function of several design parameters has been studied and based on this result, the forced vibration responses to the input electricity of various frequencies and magnitudes are investigated. The obtained results will provide an important criterion, a priori, in the design of piezoelectric motors.

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Travelling wave Type Ultrasonic Linear Motor Design and Fabrication (진행파형 초음파 리니어 모터 설계 및 제작)

  • Han Woo Seok;Kim Yeon Bo;Roh Yongrae
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.371-374
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    • 1999
  • 현재까지 초음파 모터는 소형 경량이면서도 저속에서 큰 출력을 가지며 정확한 위치 제어가 가능하다는 점에서 큰 관심을 끌고 있다. 대부분 회전형 로우터리 모터가 주종을 이루고 있으며 특수한 용도로 초음파 리니어 모터가 일부 사용되고 있다. 본 연구에서는 진행파를 이용하여 쌍방향으로 움직일 수 있는 새로운 구조의 진행파형 초음파 리니어 모터를 설계하고 제작하였다. 설계는 유한요소해석법을 이용하여 구조의 가능성과 진행파가 왜곡되지 않는 최적구조, 계질, 크기, 경계조건을 결정하였다. 그 결과에 따라 리니어 모터를 실제로 제작하여 알루미늄판 위에서 주파수 변화 및 부하질량 변화에 대한 모터의 성능을 측정하였는데, 제작된 모터는 부하질량이 100 g일 때 14.6cm/s로 가장 빠른 속도특성을 보였다. 본 모터는 다양한 정밀위치제어 및 이동 소자로서 활용될 수 있을 것이다.

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Analysis of Rectangular Microstrip Patch Antennas with the Multilayered Structure and the Electromagnetically Coupled Feed Structure (다층구조와 전자장결합 급전구조를 갖는 사각형 마이크로스트립 패치안테나의 해석)

  • 정문희;남상욱
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.2
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    • pp.18-25
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    • 1994
  • In this papaer, the input impedance of the rectangular microstrip patch antennas with the multilayered structure is analysed by using the moment method technique in the spectral domain. The analysis is carried out for two different feeding structures : directfeeding structure and electromagnetic-feeding structure. In order to obtain the accurate input impedance, the current distribution on the microstrip feed line is modeled by the quasi-TEM travelling wave and the PWS(piecewise sinusoidal) mode. The input impedances of the designed microstrip antennas are measured and compared with the calculation. which shows a good agreement.

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Numerical Study of Wavy Taylor-Couette Flow(I) -Without an Axial Flow- (Wavy Taylor-Couette 유동에 대한 전산해석 (I) -축방향 유동이 없는 경우-)

  • Hwang, Jong-Yeon;Yang, Gyeong-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.5
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    • pp.697-704
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    • 2001
  • The flow between two concentric cylinders, with the inner one rotating, is studied using numerical simulation. This study considers the identical flow geometry as in the experiments of Wereley and Lueptow[J. Fluid Mech., 364, 1998]. They carried out experiment using PIV to measure the velocity fields in a meridional plane of the annulus in detail. When Taylor number increases over the critical one, the flow instability caused by curved streamlines of the tangential flow induces Taylor vortices in the flow direction. As Taylor number further increases over another critical one, the steady Taylor vortices become unsteady and non-axisymmetrically wavy. The velocity vector fields obtained also show the same flow features found in the experiments of Wereley and Lueptow.

Verification and validation of ShipMo3D ship motion predictions in the time and frequency domains

  • Mctaggart, Kevin A.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.3 no.1
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    • pp.86-94
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    • 2011
  • This paper compares frequency domain and time domain predictions from the ShipMo3D ship motion library with observed motions from model tests and sea trials. ShipMo3D evaluates hull radiation and diffraction forces using the frequency domain Green function for zero forward speed, which is a suitable approach for ships travelling at moderate speed (e.g., Froude numbers up to 0.4). Numerical predictions give generally good agreement with experiments. Frequency domain and linear time domain predictions are almost identical. Evaluation of nonlinear buoyancy and incident wave forces using the instantaneous wetted hull surface gives no improvement in numerical predictions. Consistent prediction of roll motions remains a challenge for seakeeping codes due to the associated viscous effects.