• Title/Summary/Keyword: coupling beam

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Mode Size Converter based on Muitimode Fiber Taper (다중모드 광섬유 테이퍼를 이용한 모드 크기 변환기)

  • Kim, Kwang-Taek;Park, Kiu-Ha;Hyun, Woong-Keun;Jung, Yong-Min;Lee, Byeong-Ha
    • Korean Journal of Optics and Photonics
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    • v.18 no.4
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    • pp.280-285
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    • 2007
  • Based on the multimode fiber taper, a mode size converter for effective optical beam coupling between laser and optical fiber or between the two different optical fibers has been proposed and demonstrated. The device has a multimode input end and a single mode output end. The influence of various parameters, including device structure and launching conditions, on the coupling efficiency has been theoretically analyzed. The theoretical results revealed that the gaussian beam can be coupled into a single mode fiber without considerable insertion loss. The proposed multimode fiber taper has been fabricated using heating and pulling equipment incorporating two micro-torches. Experimental results showed that an optical beam with $50\;{\mu}m$ of large beam size was effectively coupled into single mode fiber through the multimode fiber taper. The insertion loss of the device was 1.3 dB.

The Design of a Broadband E-plane H Sectoral Horn Phased Array Antenna Using Mutual Coupling (상호 결합을 이용한 광대역 E-면 H 섹터 혼 위상 배열 안테나 설계)

  • Lee, Cheol-Soo;Pack, Jeong-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.6 s.121
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    • pp.620-628
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    • 2007
  • An H-sector horn antenna has a constant beam coverage characteristic and it can be useful for application to a wide band phased array antenna system. In this paper, we designed a broadband E-plane H-sector horn phased-array antenna, which has a 3:1 bandwidth and ${\pm}60^{\circ}$ beam steering capability. An H-sector hem antenna was designed to have $30{\sim}50^{\circ}$ half-power beam width in the principal H-plane. The active reflection coefficient including mutual coupling was calculated using a waveguide simulator, and the active reflection characteristic was improved by mutual coupling over wide frequency range. Using these results, an $8{\times}1$ H-sector phased array antenna was fabricated. The measurement results for the half-power beam width in the principal H-plane and the active reflection coefficient showed a good agreement with the simulation results. The peak-value pattern in the steered radiation beams also agreed well with the active element pattern. The measured active reflection coefficients within the beam steering range are mostly less than 0.3 over the 3:1 frequency range.

Development of photothermal mirage technique for measuring thermal diffusivity (열확산도 측정을 위한 광열 신기루 기법 개발)

  • Kim, Dong-Sik;Choi, Sun-Rock;Lee, Joo-Chul
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1395-1400
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    • 2003
  • This paper introduces a novel scheme for determining the thermal diffusivity of solids using the photothermal mirage technique. The suggested scheme extends the thermal-wave coupling method, employing the solution to the heat conduction equation in close proximity to the pump beam. Therefore, determination of thermal diffusivity is possible by detecting the mirage signal with small separation between the probe and pump beams, with enhanced intensity of the mirage signal. Though the method requires information about the probe-beam height, the absolute transverse position of the probe beam need not be known as it is automatically evaluated by the iterative-computation procedure. The thermal diffusivity of Ni is measured by the proposed scheme and the result demonstrates good agreement with the literature value to within 5 %.

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Fabrication of Polarization Gratings on the Sol-gel Film Bearing Silylated Chalcone and Disperse red 1

  • Park, Dong-Hoon;Kwon, Young-Ha
    • Macromolecular Research
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    • v.9 no.3
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    • pp.171-178
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    • 2001
  • We report the diffraction behavior of the functionalized sol-gel film composed of two different silanes. One silane (SGDR1) contains disperse red 1 (DR1) that is composed of an azobenzene unit. The other silane (SGCHC) bears a chalcone derivative that is photocrosslinkable under UV irradiation. Two-beam coupling method was employed for fabricating the diffraction gratings. The dynamics of formation and erasure of the gratings was studied in term of the variation of the diffraction efficiency. The decaying behavior of the polarization efficiency was also observed after turning off the two pump beams. For complete erasure of the diffraction gratings, we irradiated the linearly polarized single beam. During two-beam coupling, we irradiated UV light on the film surface. The effects of the photocrosslink between the double bonds in chalcone units on the value and dynamic properties of diffraction efficiency are mainly studied in this work.

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Closed-form and numerical solution of the static and dynamic analysis of coupled shear walls by the continuous method and the modified transfer matrix method

  • Mao C. Pinto
    • Structural Engineering and Mechanics
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    • v.86 no.1
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    • pp.49-68
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    • 2023
  • This study investigates the static and dynamic structural analysis of symmetrical and asymmetrical coupled shear walls using the continuous and modified transfer matrix methods by idealizing the coupled shear wall as a three-field CTB-type replacement beam. The coupled shear wall is modeled as a continuous structure consisting of the parallel coupling of a Timoshenko beam in tension (with axial extensibility in the shear walls) and a shear beam (replacing the beam coupling effect between the shear walls). The variational method using the Hamilton principle is used to obtain the coupled differential equations and the boundary conditions associated with the model. Using the continuous method, closed-form analytical solutions to the differential equation for the coupled shear wall with uniform properties along the height are derived and a numerical solution using the modified transfer matrix is proposed to overcome the difficulty of coupled shear walls with non-uniform properties along height. The computational advantage of the modified transfer matrix method compared to the classical method is shown. The results of the numerical examples and the parametric analysis show that the proposed analytical and numerical model and method is accurate, reliable and involves reduced processing time for generalized static and dynamic structural analysis of coupled shear walls at a preliminary stage and can used as a verification method in the final stage of the project.

Design Strength of Coupled Shear Wall System according to Variation of Strength and Stiffness of Coupled Shear Wall (병렬전단벽의 강도와 강성이 커플링보의 설계내력에 미치는 영향)

  • Yoon, Tae-Ho;Kim, Jin-Sang
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.10
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    • pp.743-750
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    • 2016
  • In this research, the effects of the strength and stiffness of shear walls on the design strength of coupling beams are studied in the shear wall-coupling beam structural system widely used as the lateral-drift resistant system of high-rise buildings. The results show that the design strength of the coupling beams decreases with decreasing concrete strength and core wall thickness, but the shape remains unchanged. In all six models, the design strength of the coupling beams has the largest value at the 10~15th floors in a 40-story building. In other words, the design strength of the coupling beams has the largest value at 0.25H~0.375H where the inflection point exists. The thicker the walls, the smaller the change in the member forces. The thickness of the coupled shear walls has more influence on the design strength of the coupling beams than the concrete strength.

Design of a Tilted Beam Microstrip Patch Array Antenna using Parasitic Patch Coupling Characteristics (기생 패치의 결합 특성을 이용한 빔 틸팅 마이크로스트립 패치 배열 안테나 설계)

  • 하재권;박동철
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.2
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    • pp.202-208
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    • 2003
  • In this paper, we proposed a microstrip patch array antenna for DBS reception which had high gain and high tilted angle through mutual coupling driver patch to parasitic patch in H-plane edge and broadside direction in different layers. It was designed and fabricated in 16$\times$8 array by using low cost polyester based copper-clad laminate and foam instead of high cost dielectric substrate. It had gain of 22.9 dBi, beamwidth of 4.6$^{\circ}$, and tilted angle from broadside direction of 43.9$^{\circ}$.

Real-time Optical Logic Processors by Two-Wave Mixing in $BaTiO_3$ Crystal ($BaTiO_3$ 결정에서의 두 광파 혼합현상을 이용한 광 논리처리기)

  • 김기홍;권원현;오창석;박한규
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.10
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    • pp.1571-1575
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    • 1989
  • Nonlinear beam coupling phenomena in photorefractive materials are analyzed as a function of the input beam intensities. Signal beam saturation and pump beam depletion are shown to be the intensity-dependent functions of these materials. Utilizing these phenomena in a photorefractive BaTiO3 crystal, optical logic processors such as AND, OR, NOT, etc., are implemented.

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Beam cone analysis and its applications for the beams obliquely input to dielectric boundaries (유전체 경계면에 경사지게 입사하는 beam cone의 해석과 그 응용)

  • 이병호;민성욱
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.5
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    • pp.142-148
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    • 1996
  • It is shown that a simple vector analysis method can provide beam cone shapes for laser bemas non-paraxially input to dielectric boundaries with inclination. Acceptance coen shapes for angled-endface fibers are calculated by the method. Beam cone shapes inside InP substrates are also calculated by the method for the coupling of an optical fiber and an InP-based photodiode using a Si v-groove. The effectiveness and errors of the recently suggested matrix method for inclined boundaries are also studied.

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Design of Cylindrical Composite Shell for Optimal Dimensions (최적 단면 치수를 가지는 복합재료 중공 빔의 설계)

  • 최용진;전흥재;박혁성
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.127-133
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    • 2003
  • In this study, a problem formulation and solution for design optimization of laminate composite cylindrical beam section is presented. The objective of this research is to determine the optimal dimension of the laminated composite cylindrical beam sections which has the equivalent flexural rigidities to those of the steel cylindrical beam sections. The analytical model is based on the laminate theory and accounts for the material coupling for arbitrary laminate stacking sequence configuration. The outer diameter and thickness of the beam are design variables. The solutions described are found using a global search algorithm, Genetic Algorithms (GA).

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