• Title, Summary, Keyword: Matching Frequency

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A New Stereo Matching Algorithm based on Variable Windows using Frequency Information in DWT Domain (DWT 영역에서의 주파수 정보를 활용한 가변 윈도우 기반의 스테레오 정합 알고리즘)

  • Seo, Young-Ho;Koo, Ja-Myung;Kim, Dong-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.7
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    • pp.1437-1446
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    • 2012
  • In this paper we propose a new stereo matching algorithm which is suitable for application to obtain depth information with high-speed in stereoscopic camera environment. For satisfying these condition we propose a new adaptive stereo matching technique using frequency information in discrete wavelet (DWT) domain and variable matching window. The size of the matching window is selected by analysis of the local property of the image in spatial domain and the feature and scaling factor of the matching window is selected by the frequency property in the frequency domain. For using frequency information we use local DWT and global DWT. We identified that the proposed technique has better peak noise to signal ratio (PSNR) than the fixed matching techniques with similar complexity.

Control of Matching Frequency of Ferrite Composite Microwave Absorber Consisted of Two Kinds of Ferrites (2종의 Ferrite가 혼합된 복합 Ferrite 전파흡수체의 정합주파수 제어)

  • 권형주;신재영;오재희
    • Journal of the Korean Ceramic Society
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    • v.30 no.10
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    • pp.823-828
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    • 1993
  • The performance of ferrite composite microwave absorber has been evaluated as the matching frequency, the matching thickness and the band width. Especially, matching frequency is very important in application of microwave absorber because it determines operating frequency range. In this study, the ferrite composite microwave absorbers consisted Ni-Zn ferrite and Zn2Y ferroxplana were prepared in order to control matching frequency. Then, the variation of the material constants and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite composite microwave absorber could be controlled by variation ferrite mixing ratio. Therefore, it was confirm that matching frequency of microwave absorber could be shifted by control of material constants.

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THE COMPLEX PERMEABILITY AND MATCHING FREQUENCY OF FERRITE MICROWAVE ABSORBER

  • Shin, Jae-Young;Oh, Jae-Hee
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.800-804
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    • 1995
  • The complex permeability dispersions and the microwave absorbing phenomena are investigated in ferrite microwave absorber. The complex permeability of NiZn ferrite, NiZnCo ferrite, and Y-type hexagonal ferrite were measured in 200MHz-14GHz range. Two types of resonances, the domain wall and the spin rotational resonance, were observed. With a ferrite particle with a diameter of about $1\;\mu\textrm{m}$, only spin rotational resonance were observed. The theoretical matching frequency is determined by plotting the measured complex permeability locus on the impedance matching solution map. One or two impedance matching phenomena are observed in the ferrite absorbers according to their complex permeability loci on the impedance matching solution map. The first matching frequency, found in the ferrite-rubber composites, which was higher than that of spin rotational resonance, increased with spin rotational resonance frequency.

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Improved Impedance Matching of Dual-Frequency Microstrip Printed-Dipole Antenna with Conductor Back

  • Tangjitjesada, M.;Anantrasirichai, N.;Wakabayashi, T.
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1668-1671
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    • 2003
  • A novel dual-frequency microstrip printed-dipole antenna operating at 5 GHz and 10 GHz is presented. This antenna is designed for wireless and mobile communication. The balance step coplanar strip is used to be a transmission line at the center of dipole with matching impedance at 50 ohm. Using the conductor strip align on the other side of antenna and adjust the width of step coplanar strip line to improved input impedance matching. By modification for matching impedance of dual frequency antenna are not affected to the radiation patterns. The Finite Difference Time Domain (FDTD) technique is applying to analyze the basic characteristic properties such as $S_{11}$ , input impedance , VSWR and radiation patterns. And these parameters are discussed. The analyze problem space are $51{\times}197{\times}175$ cells and cell dimension are ${\Delta}x=0.3\;mm$ and ${\Delta}y={\Delta}z=0.15\;mm$.

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Frequency Tuning Characteristics of a THz-wave Parametric Oscillator

  • Li, Zhongyang;Bing, Pibin;Xu, Degang;Yao, Jianquan
    • Journal of the Optical Society of Korea
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    • v.17 no.1
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    • pp.97-102
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    • 2013
  • Frequency tuning characteristics of a THz-wave by varying phase-matching angle and pump wavelength in a noncollinear phase-matching THz-wave parametric oscillator (TPO) are analyzed. A novel scheme to realize the tuning of a THz-wave by moving the cavity mirror forwards and backwards is proposed in a noncollinear phase-matching TPO. The parametric gain coefficients of the THz-wave in a $LiNbO_3$ crystal are explored under different working temperatures. The relationship between the poling period of periodically poled $LiNbO_3$ (PPLN) and the THz-wave frequency under the condition of a quasi-phase-matching configuration is deduced. Such analyses have an impact on the experiments of the TPO.

The Characteristics of Electromagnetic Wave Absorption in Sintered and Composite Ni-Zn Ferrites (니켈-아연 페라이트 소결체와 복합체의 전파흡수특성)

  • 조성백;오재희
    • Journal of the Korean Ceramic Society
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    • v.32 no.1
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    • pp.25-30
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    • 1995
  • The frequenc dependence of magnetic permeability($\mu$r) and dielectric constant($\varepsilon$r) in MHz-GHz frequency range and their relationships with microwave absorbing properties were investigated in sintered and composite Ni-Zn ferrites, respectively. It was confirmed that zero reflection condition was required the real parts of permeability and permittivity in sintered specimen, and the complex permeability, permittivity and dielectric loss tangent in composite specimen. The real part of permittivity varied with the replacement of nickel by manganese in sintered Ni-Zn ferrite. Therefore, we could control the matching frequency and matching thickness.

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Model Order Reduction Using Moment-Matching Method Based on Krylov Subspace and Its Application to FRF Calculation for Array-Type MEMS Resonators (Krylov 부공간에 근거한 모멘트일치법을 이용한 모델차수축소법 및 배열형 MEMS 공진기 주파수응답함수 계산에의 응용)

  • Han, Jeong-Sam;Ko, Jin-Hwan
    • Proceedings of the KSME Conference
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    • pp.436-441
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    • 2008
  • One of important factors in designing array-type MEMS resonators is obtaining a desired frequency response function (FRF) within a specific range. In this paper Krylov subspace-based model order reduction using moment-matching with non-zero expansion points is represented to calculate the FRF of array-type resonators. By matching moments at a frequency around a specific range of the array-type resonators, required FRFs can be efficiently calculated with significantly reduced systems regardless of their operating frequencies. In addition, because of the characteristics of moment-matching method, a minimal order of reduced system with a specified accuracy can be determined through an error indicator using successive reduced models, which is very useful to automate the order reduction process and FRF calculation for structural optimization iterations.

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Design of the Novel DVB-H Antenna for the Folder-Type Mobile Handheld Terminal

  • Lee, Jung-Nam;Park, Jong-Kweon;Kim, Jin-Suk
    • Journal of electromagnetic engineering and science
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    • v.8 no.1
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    • pp.28-33
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    • 2008
  • We have proposed a novel DVB-H(Digital Video Broadcast for Handheld) antenna for folder-type mobile handheld terminal by using a coupling element, a stub, and an L-type matching circuit. The L-type matching circuit consisting of two chip inductors is used for achieving an improved impedance matching over the DVB-H frequency band ($470{\sim}702\;MHz$). Simulated results showed the stub worked to more knot the lower and upper frequency ends of the input impedance curve. The antenna exhibits a flat gain characteristic from 2 to 2.8 dBi over the DVB-H frequency band. The radiation patterns are a stable Figure-of-eight radiation pattern in the frequency range.

Joint Subcarrier Matching and Power Allocation in OFDM Two-Way Relay Systems

  • Vu, Ha Nguyen;Kong, Hyung-Yun
    • Journal of Communications and Networks
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    • v.14 no.3
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    • pp.257-266
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    • 2012
  • A decode-and-forward two-way relay system benefits from orthogonal frequency division multiplexing (OFDM) and relay transmission. In this paper, we consider a decode-and-forward two-way relay system over OFDMwith two strategies: A joint subcarrier matching algorithm and a power allocation algorithm operating with a total power constraint for all subcarriers. The two strategies are studied based on average capacity using numerical analysis by uniformly allocating power constraints for each subcarrier matching group. An optimal subcarrier matching algorithm is proposed to match subcarriers in order of channel power gain for both transmission sides. Power allocation is defined based on equally distributing the capacity of each hop in each matching group. Afterward, a modified water-filling algorithm is also considered to allocate the power among all matching groups in order to increase the overall capacity of the network. Finally, Monte Carlo simulations are completed to confirm the numerical results and show the advantages of the joint subcarrier matching, power allocation and water filling algorithms, respectively.

Investigation of Terahertz Generation from Bulk and Periodically Poled LiTaO3 Crystal with a Cherenkov Phase Matching Scheme

  • Li, Zhongyang;Bing, Pibin;Yuan, Sheng;Xu, Degang;Yao, Jianquan
    • Journal of the Optical Society of Korea
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    • v.19 no.3
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    • pp.297-302
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    • 2015
  • Terahertz (THz) wave generation from bulk and periodically poled $LiTaO_3$ (PPLT) with a Cherenkov phase matching scheme is numerically investigated. It is shown that by using the crystal birefringence of bulk $LiTaO_3$ and a grating vector of PPLT, THz waves can be efficiently generated by difference frequency generation (DFG) with a Cherenkov phase matching scheme. The frequency tuning characteristics of the THz wave via varying wavelength of difference frequency waves, phase matching angle, poling period of PPLT and working temperature are theoretically analyzed. The parametric gain coefficient in the low-loss limit and the absorption coefficient of the THz wave during the DFG process in the vicinity of polariton resonances are numerically analyzed. A THz wave can be efficiently generated by utilizing the giant second order nonlinearities of $LiTaO_3$ in the vicinity of polariton resonances.