• Title/Summary/Keyword: Circular pattern

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Radiation Characteristics of a Circular Loop Antenna in Moving Media. (운동매질내에서의 Circula Loop Antenna의 방사특성(II))

  • 최병하
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.9 no.2
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    • pp.17-23
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    • 1972
  • In this paper, the radiation characteristics of a large circular loop antenna with sinusoidal current distribution is studded in a moving media with a constant velocity much less than the speed of light. The diameter of the circular loop antenna is comparable with or larger than wave length. In studing the radiation characteristics, vector potential for the antenna is derived and relative field pattern is plotted from the vector potentials. Finally the field patterns are compared with those of stationary media. It is found that maximum directivities are shifted to the direction of the velocity of the media, and the field intensities are decreased in that direction and increased in opposite direction by the velocity component paralell to the loop plane. It is also found that the deviations for the pattern are proportional to the velocity of the media, the frequency of the distributed current, the diameter of the loop antenna, and the daviation depends only upon the parallel component of the velocity to the loop plane.

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Rotation-Invariant Pattern Recognition of the Multiple Circular Harmonic Filter Using Proper Center (적정의 중심점을 이용한 다중 원형 고조 필터의 회전 불변적 형태 인식)

  • 김종찬;도양회;김수중
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.1
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    • pp.130-136
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    • 1990
  • For the rotation-invariant pattern recognition, we propose multiple circular harmonic filter which is expanded about the proper center. The proper centerm when input image is given, is the circular harmonic expansion center of the filter which yields a maximum center correlation peak in the output plane. In this paper, we founded the circular harmonic components that the proper center superposes on the same position and then designed multiple circular harmonic filter using these components. Also the proposed filter is compared with conventional multiple circular harmonic filter and shows that it can maximize the center correlation peak for the rotated input image by the computer simulation.

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attenuation pattern of the electromagnetic fields scattered by two empty circular cylinders in a dielectric medium (유전체 내의 두개의 빈 원기둥에 의해 산란된 전자파의 감쇄패턴)

  • 이택경;김세윤;라정웅
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.4
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    • pp.92-97
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    • 1996
  • The attenuation pattern of the E-polarized electromagnetic fields scattered by two empty circular cylinders in a dielectric medium is analyzed to calculate the effects of the inhomogenuity in hte background medium. Inthe amplitude pattern of the electromagnetic field scattered by one cylinder, double dips occur at the locations corresponding to its top and bottom boundaries. The distorton of the original double dip pattern is calculated when other air cavity approaches or its size increases.

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An Indoor Pose Estimation System Based on Recognition of Circular Ring Patterns (원형 링 패턴 인식에 기반한 실내용 자세추정 시스템)

  • Kim, Heon-Hui;Ha, Yun-Su
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.4
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    • pp.512-519
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    • 2012
  • This paper proposes a 3-D pose (positions and orientations) estimation system based on the recognition of circular ring patterns. To deal with monocular vision-based pose estimation problem, we specially design a circular ring pattern that has a simplicity merit in view of object recognition. A pose estimation procedure is described in detail, which utilizes the geometric transformation of a circular ring pattern in 2-D perspective projection space. The proposed method is evaluated through the analysis of accuracy and precision with respect to 3-D pose estimation of a quadrotor-type vehicle in 3-D space.

Radiation characteristics of A Circular Loop antenna In Moving Media (운동매질내에서의 Circular Loop Antenna의 개체특성)

  • 최병하
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.7 no.3
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    • pp.12-18
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    • 1970
  • In this paper, the radiation characteristics of a Circular Loop Antenna is studied in a moving homogeneous, isotropic and linear media with a constant velocity much less than the speed of light. In Stuffing the radiation characteristics, Srst vector potential on the loop antenna is derived in the moving media by appling Maxwell-Minkowaski's theory. Next, using the derived relations, the electric and magnetic Seld is calculated for the spec-i Sed wave length ana velocity of the media. The Seld patterns in the moving media are compared with those of stationary media. We find that the intensity of the field is reduced in the direction of the media velocity and increased in the opposite direction only for the component parallel with the plane of the antenna. The deviation from the stationary media is proportional to the velocity of the media and the frequency of source current.

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Flow pattern in the presence of two nearby circular cylinders (두 개의 원형 실린더 주위의 유동 패턴)

  • Lee, Kyong-Jun;Yang, Kyung-Soo
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2851-2856
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    • 2007
  • Flow patterns in the presence of two identical nearby circular cylinders at =100 were numerically studied. We considered all possible arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. Eight distinct flow patterns were identified based on vorticity contours and streamlines, which are Base-Bleed, Biased-Base-Bleed, Shear- Layer-Reattachment, Induced-Separation, Vortex-Impingement, Flip-Flopping, Modulated Periodic, and Synchronized-Vortex-Shedding. Collecting all the numerical results, we propose a general flow pattern diagram for flows past the two cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use this diagram to distinguish flow patterns in the presence of two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.

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Flow Pattern in the Presence of Two Nearby Circular Cylinders (두 개의 원형 실린더 주위의 유동 패턴)

  • Lee, Kyong-Jun;Yang, Kyung-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.8
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    • pp.724-732
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    • 2007
  • Flow patterns in the presence of two identical nearby circular cylinders at Re=100 were numerically studied. We considered all possible arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. Eight distinct flow patterns were identified based on vorticity contours and streamlines, which are Base-Bleed, Biased-Base-Bleed, Shear-Layer-Reattachment, Induced-Separation, Vortex-Impingement, Flip-Flopping, Modulated Periodic, and Synchronized-Vortex-Shedding. Collecting all the numerical results, we propose a general flow pattern diagram for flows past two nearby cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use this diagram to distinguish flow patterns in the presence of two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.

The Design and Manufacture of Ku-Band Circular Waveguide with Circular Polarizaed Wave Characteristic (원편파 특성을 갖는 Ku-밴드 원형도파관 안테나 설계 및 제작)

  • 이성재
    • Journal of the Korea Institute of Military Science and Technology
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    • v.4 no.1
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    • pp.124-136
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    • 2001
  • In this paper, we designed and manufactured the Ku-band circular waveguide antenna to do wireless communication with a ground radar as on-board antenna of missile. Using the MATLAB and the HFSS, we designed the circular polarizer which has a characteristic of circular polarization and broadband using the capacitive pin method, the feeder to feed coaxial line to circular waveguide, and a stopper to prevent a conductor material from being inserted. Then we simulated the designed antenna using the HFSS, obtained the gain and the radiation pattern. Because of a difficulty of manufacture, we established a manufacture process procedure. Antenna is manufactured with this procedure, test results of the manufactured antenna are the axial ratio of 1.37 ~ 1.72, the 3 ㏈ beamwidth of $72.23^{\circ}{\sim}78.54^{\circ},$ and the gain of 3.26 ~ 4.61 ㏈ within frequency band. We knew that these results are similar with simulation results. Also, we confirmed that the manufactured antenna is satisfied with requirement conditions through performance test, environmental test and flight test.

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Analysis of Dynamic Characteristics and Improvement of Vibration Table for Expendable Pattern Casting Process (소실모형주조용 진동장치의 동특성 분석 및 개선)

  • 이은경;설진수;이경환;최경환;임경화
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.3
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    • pp.185-192
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    • 2004
  • Vibration table is required to obtain high packing density in expendable pattern casting process. Packing density. which is an important manufacture factor, depends on the vibration pattern induced by vibration table. In general, circular vibration pattern is recognized as the best pattern. The existing vibration table is investigated to identify current vibration pattern and consider a countermeasure. Modal test is utilized to identify the dynamic characteristics of vibration table, and finite element method is used to propose the improved design. In simulation using finite element method, the position of stiffeners is obtained to satisfy the required dynamic characteristics.

Performance Evaluation Of Vibrating Table for Expendable Pattern Casting Process (소실모형주조용 진동장치의 성능평가)

  • Lee, Eun-Kung;Rim, Kyung-Hwa;Lee, Kyung-Whoan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.160-165
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    • 2002
  • Vibration table is required to obtain high packing density in expendable pattern casting process. Packing density, which is an important manufacture factor, depends on the vibration pattern induced by vibration table. In general, circular vibration pattern is recognized as the best pattern. The existing vibration table is investigated to identify current vibration pattern and consider a countermeasure. Modal test is utilized to identify the dynamic characteristics of vibration table, and finite element method is used to present the improved design.

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