• Title/Summary/Keyword: Coupled Mode Theory

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Modeling and Characteristics of $K^{+}$ Ion-exchanged Waveguide-type Optical Coupler ($K^{+}$ 이온교환 도파로형 광결합기의 모델링 및 특성)

  • 천석표;박태성;정홍배
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.11a
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    • pp.194-197
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    • 1995
  • In this study, we performed a modeling for $K^{+}$ ion-exchanged diffused channel waveguide and waveguide-type optical coupler by WKB(Wentzel-Kramer-Brillouim) dispersion equation, field distribution equation of mode and coupled mode theory, and examined the optical-power-dividing of the optical coupler fabricated by using the modeling condition. The optical-power-dividing was observed at the waveguide-type optical coupler with 3[$\mu\textrm{m}$] line-width, 6[$\mu\textrm{m}$] space between channel waveguides, and 3[mm] interaction length.

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Dynamical transition of Josephson vortex lattice in serially stacked ${Bi_2}{Sr_2}{CaCu_2}{O_{8+x}}$ intrinsic Josephson junctions

  • Myung-Ho;Hu-Jong
    • Progress in Superconductivity
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    • v.6 no.1
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    • pp.52-55
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    • 2004
  • The inductive coupling theory in serially stacked $Bi_2$$Sr_2$$CaCu_2$$O_{8+x}$ intrinsic Josephson junctions predicts that the lattice structure of the Josephson vortices along the c axis gradually changes from the triangular to the rectangular lattice with increasing the vortex velocity. This lattice transition appears as voltage jumps or sub-branch splitting in the Josephson vortex-flow region of current-voltage characteristics (IVC). We report the IVC in external magnetic fields from 2 to 4 T. The stack, with the lateral size of 1.4${\times}$15 $u\m^2$, was fabricated by using the double-side cleaving technique. The sub-branches in the Josephson vortex-flow region, corresponding to a plasma propagation mode in serially coupled intrinsic Josephson junctions, were also observed in the range of 2∼4T. Switching from one branch to another in Josephson vortex-flow region suggests the structural transition of the moving Josephson vortex lattice.

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Stability Analysis of Pipe Conveying Fluid with Crack (크랙을 가진 유체유동 파이프의 안정성 해석)

  • Son, In-Soo;Ahn, Tae-Su;Yoon, Han-Ik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.1 s.118
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    • pp.10-16
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    • 2007
  • In this paper, the dynamic stability of a cracked simply supported pipe conveying fluid is investigated. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid due to the coupled mode(modes combined) is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Galerkin method. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The stiffness of the spring depends on the crack severity and the geometry of the cracked section. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. This results of study will contribute to the safety test and a stability estimation of the structures of a cracked pipe conveying fluid.

Optical coupling between a side polished fiber and planar waveguide including a thin metal film (측면 연마 광섬유가 금속 박막이 포함된 평면 도파로 사이의 광 결합)

  • 김광택;황중호;이준옥;김상우;강신원;서동일;손재원
    • Korean Journal of Optics and Photonics
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    • v.12 no.5
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    • pp.406-413
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    • 2001
  • We report theoretical and experimental results for the wavelength and polarization selectivity of a fiber-to-planar waveguide coupler made of a side polished single mode fiber covered with a planer waveguide incorporating a thin metal film. A simple but exact approach to obtain the modal properties of multilayer planar waveguide with a thin metal film is described. The device was modeled into equivalent 1 dimensional structure and its behaviour was analyzed based on coupled mode theory. The effects of metal film thickness and refractive index of superstrate on the device properties were measured and explained.

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A state space method for coupled flutter analysis of long-span bridges

  • Ding, Quanshun;Chen, Airong;Xiang, Haifan
    • Structural Engineering and Mechanics
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    • v.14 no.4
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    • pp.491-504
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    • 2002
  • A state-space method is proposed to analyze the aerodynamically coupled flutter problems of long-span bridges based on the modal coordinates of structure. The theory about complex modes is applied in this paper. The general governing equation of the system is converted into a complex standard characteristic equation in a state space format, which contains only two variables. The proposed method is a single-parameter searching method about reduced velocity, and it need not choose the participating modes beforehand and has no requirement for the form of structure damping matrix. The information about variations of system characteristics with reduced velocity and wind velocity can be provided. The method is able to find automatically the lowest critical flutter velocity and give relative amplitudes, phases and energy ratios of the participating modes in the flutter motion. Moreover, the flutter analysis of Jiangyin Yangtse suspension bridge with 1385 m main span is performed. The proposed method has proved reliable in its methodology and efficient in its use.

Dual-phase-lag model on microstretch thermoelastic medium with diffusion under the influence of gravity and laser pulse

  • Othman, Mohamed I.A.;Abd-Elaziz, Elsayed M.;Mohamed, Ibrahim E.A.
    • Structural Engineering and Mechanics
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    • v.75 no.2
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    • pp.133-144
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    • 2020
  • This investigation is to study the effect of gravitational field and diffusion on a microstretch thermoelastic medium heating by a non-Gaussian laser beam. The problem was studied in the context of the dual-phase-lag model. The normal mode analysis is used to solve the problem to obtain the exact expressions for the non-dimensional displacement components, the micro-rotation, the stresses, and the temperature distribution. The effect of time parameter, heat flux parameter and gravity response of three theories of thermoelasticity i.e. dual-phase-lag model (DPL), Lord and Shulman theory (L-S) and coupled theory (CT) on these quantities have been depicted graphically for a particular model.

Free Vibration Analysis of a Rotating Cantilever Beam Made-up of Functionally Graded Materials (경사기능재료를 사용한 회전하는 외팔보의 진동해석)

  • Lee, Ki Bok;Yoo, Hong Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.8
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    • pp.742-751
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    • 2013
  • The vibration analysis of a rotating cantilever beam made-up of functionally graded materials is presented based on Timoshenko beam theory. The material properties of the beams are assumed to be varied through the thickness direction following a simple power-law form. The frequency equations, which are coupled through gyroscopic coupling terms, are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. In this study, resulting system of ordinary differential equations shows the effects of power-law exponent, angular speed, length to height ratio and Young's modulus ratio. It is believed that the results will be a reference with which other researchers and commercial FE analysis program, ANSYS can compare their results.

Vibration Analysis of Rotating Inward Cantilever Beams With a Tip-Mass (집중질량을 갖는 회전중심방향 자유단 외팔보의 진동해석)

  • Lee, Gun Ho;Yoo, Hong Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.389-391
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    • 2014
  • The Vibration Analysis of Rotating Inward Beams Considering The Tip-Mass is presented based on Euler-Bernoulli beam theory. The frequency equations, which are coupled through gyroscopic coupling terms, are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. In this study, resulting system of ordinary differential equations shows the effects of angular speed, and Young's modulus ratio. It is believed that the results will be a reference with which other researchers and commercial FE analysis program, ANSYS can compare their results.

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Theoretical Studies of Surface Diffusion : Multidimensional TST and Effect of Surface Vibrations

  • 곽기정;신석민;이상엽;신국조
    • Bulletin of the Korean Chemical Society
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    • v.17 no.2
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    • pp.192-198
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    • 1996
  • We present a theoretical formulation of diffusion process on solid surface based on multidimensional transition state theory (TST). Surface diffusion of single adatom results from hopping processes on corrugated potential surface and is affected by surface vibrations of surface atoms. The rate of rare events such as hopping between lattice sites can be calculated by transition state theory. In order to include the interactions of the adatom with surface vibrations, it is assumed that the coordinates of adatom are coupled to the bath of harmonic oscillators whose frequencies are those of surface phonon modes. When nearest neighbor surface atoms are considered, we can construct Hamiltonians which contain terms for interactions of adatom with surface vibrations for the well minimum and the saddle point configurations, respectively. The escape rate constants, thus the surface diffusion parameters, are obtained by normal mode analysis of the force constant matrix based on the Hamiltonian. The analysis is applied to the diffusion coefficients of W, Ir, Pt and Ta atoms on the bcc(110) plane of W in the zero-coverage limit. The results of the calculations are encouraging considering the limitations of the model considered in the study.

Light Coupling and Propagation Between a Fiber and a Dielectric Slab with a Conductor Cladding (측면 연마된 광섬유와 완전도체면 아래의 유전체 사이에서의 결합과 전파특성의 해석)

  • Kwon, Kwang-Hee;Yoon, Ki-Hong;Kim, Jeong-Hoon;Song, Jae-Won;Park, Euy-Dong;Son, Seok-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.2A
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    • pp.70-79
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    • 2003
  • A theoretical presentation of evanescent coupling is offered with respect to the refractive indexes between a side polished optical fiber and an infinitely planar waveguide with a conductor cladding(PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with the perfect conductor(PEC) on one side. The behavior of the distributed coupler is examined using a coupled mode model, which takes account of the two dimensions of the waveguide configuration. The coupling and propagation of light were found to depend on both the relationship between the refractive index values of each structure and the configuration of the side polished fiber used in the PWGCC. The spreading of light in the unconfined direction of the PWGCC is described in terms of a simple geometrical interpretation of the synchromization condition that is in agreement with a previous investigation of the problem based on the coupled-mode theory(CMT). The power of the light propagation in the fiber decreased exponentially along the fiber axis as it was transferred to the PWGCC.