• Title/Summary/Keyword: 반사기

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A High Radiation Efficiency and Narrow Beam Width of Optical Beam Steering Using a Silicon-based Grating Structure Integrated with Distributed Bragg Reflectors (분배 브래그 반사기가 집적된 실리콘 기반 격자 구조를 이용한 광학 빔 방사 효율 및 조향 선폭 성능 향상)

  • Hong, Yoo-Seung;Cho, Jun-Hyung;Sung, Hyuk-Kee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.23 no.3
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    • pp.311-317
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    • 2019
  • We first numerically analyzed the characteristics of a silicon-based grating structure for beam steering. The analysis includes the basic principle of the grating structure according to the wavelength, peak radiation angle, radiation efficiency, and full-width at the half maximum(FWHM) of the radiation angle. Based on the analysis, we propose a silicon-based grating structure integrated with distributed Bragg reflector(DBR) to obtain a high radiation efficiency and narrow beam width simultaneously. We performed the numerical optimization of the radiation efficiency and FWHM of the radiation angle according to the DBR position. By the design optimization using the proposed grating structure compatible with the complementary metal-oxide semiconductor(CMOS) process, we achieved a maximum radiation efficiency of 87.1% and minimum FWHM of radiation angle of $4.68^{\circ}$.

A Study on the X-Band Active Radar Reflector for safety at the Sea (해상 안전을 위한 X밴드 능동형 레이더 반사기에 관한 연구)

  • 정종혁;김남호;양규식
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.3 no.4
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    • pp.849-858
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    • 1999
  • There are several improved designs of passive radar reflector available, but their performance is ultimately limited by the cross-section area and this is governed by the size of the buoy and the acceptable windage. Therefore it is needed to investigate the low-cost, low power, a active device that can be improve the reliability of response. Active Radar Reflector(AAR) consists of a microwave amplifier with separate receive and transmit antennas. It is a device which automatically transmits a signal in response to an interrogating signal received. It was intended to improve the consistency of the radar return from the buoy and the small craft, particularly in poor sea conditions. And it directly improves safety of navigation at sea.

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Reverse-time Migration using Surface-related Multiples (자유면 기인 겹반사파를 이용한 거꿀시간 참반사 보정)

  • Lee, Ganghoon;Pyun, Sukjoon
    • Geophysics and Geophysical Exploration
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    • v.21 no.1
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    • pp.41-53
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    • 2018
  • In the traditional seismic processing, multiple reflections are treated as noise and therefore they are eliminated during data processing. Recently, however, many studies have begun to consider multiples as signals rather than noise for seismic imaging. Multiple reflections can illuminate an area where primary reflections are not able to cover, thus it is allowed that a smaller number of shots and receivers are used for imaging large areas. In order to verify this, surface-related multiples were used for reverse-time migration (RTM), and then we compared the results with conventional RTM images which are generated from primary reflections. To utilize multiples, we separated multiples from whole seismic data using surface-related multiple elimination (SRME) method. Numerical examples confirmed that the migration using multiples can image wider area than the conventional migration, particularly in the shallow subsurface layers. In addition, the migration of multiples could eliminate the acquisition footprints.

Effective measurement of high facet reflectivity using the variation longitudinal modes spacing of semiconductor external cavity ring lasers (반도체 외부 공진기 링 레이저의 종 모드 간격 변화를 이용한 고반사율을 갖는 Etalon Coating Reflectivity의 정밀 측정)

  • 엄진섭;안상호
    • Korean Journal of Optics and Photonics
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    • v.10 no.6
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    • pp.524-526
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    • 1999
  • It is observed that the mode spacing of an cxternal cavity semiconducror laser can be altered dramatically by the insertion of an intracavity etalon. 111e mode spacing is decreased as a function of etalon's reflectivity and this effect is quantitatively explained by an analysis of resonant modes. We abo show that this effect provides a precise and convenient alternative for determining the coating reflectivity of a high reflectivity etalon. talon.

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Analysis of Radar Cross Section for Naval Vessels with Metamaterials and Radar Absorbing Materials (메타물질 및 전파흡수체를 적용한 함정의 레이다 반사면적 해석)

  • Hwang, Joon-Tae;Hong, Suk-Yoon;Kwon, Hyun-Wung;Kim, Jong-Chul;Song, Jee-Hun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.21 no.6
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    • pp.737-743
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    • 2015
  • This paper are mainly focusing on the facts influencing on RCS reductions, appling radar absorbing materials by using RCS contributions of elements and appling a metamaterials which is high-tech radar absorbing materials. RCS analysis results are given for a simplified ship model, with radar absorbing materials and metamaterials cause RCS reduction in terms of mean values.

Stylized Specular Reflections Using Projective Textures based on Principal Curvature Analysis (주곡률 해석 기반의 투영 텍스처를 이용한 스타일 반사 효과)

  • Lee, Hwan-Jik;Choi, Jung-Ju
    • Journal of the HCI Society of Korea
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    • v.1 no.1
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    • pp.37-44
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    • 2006
  • Specular reflections provide the visual feedback that describes the material type of an object, its local shape, and lighting environment. In photorealistic rendering, there have been a number of research available to render specular reflections effectively based on a local reflection model. In traditional cel animations and cartoons, specular reflections plays important role in representing artistic intentions for an object and its related environment reflections, so the shapes of highlights are quite stylistic. In this paper, we present a method to render and control stylized specular reflections using projective textures based on principal curvature analysis. Specifying a texture as a pattern of a highlight and projecting the texture on the specular region of a given 3D model, we can obtain a stylized representation of specular reflections. For a given polygonal model, a view point, and a light source, we first find the maximum specular intensity point, and then locate the texture projector along the line parallel to the normal vector and passing through the point. The orientation of the projector is determined by the principal directions at the point. Finally, the size of the projection frustum is determined by the principal curvatures corresponding to the principal directions. The proposed method can control the position, orientation, and size of the specular reflection efficiently by translating the projector along the principal directions, rotating the projector about the normal vector, and scaling the principal curvatures, respectively. The method is be applicable to real-time applications such as cartoon style 3D games. We implement the method by Microsoft DirectX 9.0c SDK and programmable vertex/pixel shaders on Nvidia GeForce FX 7800 graphics subsystems. According to our experimental results, we can render and control the stylized specular reflections for a 3D model of several ten thousands of triangles in real-time.

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Effect of Foot Reflexology on the Vital Signs, Blood Cortisol, Lymphocytes and Natural Killer Cell of Female Cancer Patients (발반사마사지가 여성암환자의 활력징후, 코티졸, 면역반응에 미치는 효과)

  • Kim, Keum-Soon;Won, Jong-Soon;Jeong, Ihn-Sook;Choi, Wan-Hee;Kang, Ji-Yeon
    • Journal of Korean Biological Nursing Science
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    • v.6 no.1
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    • pp.5-15
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    • 2004
  • 목적 : 이 연구는 항암제를 투여받는 여성암환자에서 발반사마사지가 스트레스반응(활력징후, 코티졸)과 면역반응에 미치는 효과를 평가하기 위함이다. 방법 : 11명의 여성암 환자를 임의로 표출한 후 단일군 전후실험설계로 진행하였다. 종속변수는 스트레스 반응으로 활력징후(수축기 혈압, 이완기 혈압, 맥박수, 호흡수)와 혈중 코티졸, 면역반응으로 림프구 아군(CD3, CD4, CD8, CD19)과 자연살세포(NK cells)이며, 독립변수는 발반사마사지이었다. 중재 전후 종속변수의 변화를 보기 위해 Wilcoxon signed rank test를 실시하였다. 결과 : 중재 전에 비해 중재 후 수축기 혈압, 이완기 혈압, 맥박수, 혈중 코티졸치, CD4와 CD19는 유의한 변화를 보였으나 호흡수, CD3, CD8, 그리고 자연살세포는 유의한 변화를 보이지 않았다. 결론 : 이러한 연구결과는 발반사마사지가 항암화학요법을 받는 여성암 환자의 스트레스 호르몬과 면역관련세포에 영향을 보였지만 표본수가 작고 중재가 1회에 그쳤기 때문에 이러한 단점을 보완한 추후연구를 통해 발반사마사지의 효과를 좀더 잘 규명할 수 있을 것이다.

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Design of Patch Array Antenna for UAV with Horn Reflector (혼 반사기를 적용한 UAV용 패치배열 안테나 설계)

  • Seong-hun Kim;Ji-hwan Ko
    • Journal of Advanced Navigation Technology
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    • v.27 no.6
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    • pp.828-834
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    • 2023
  • In this paper, we studied an antenna that forms a wide beam width by applying a horn-shaped reflector to a patch array antenna. To implement a wide beam width, three patches were arranged in each of the four directions on a square microstrip substrate, and a horn-shaped reflector was applied to the rear of the array antenna. Through this structure, the vertical beam pattern formed from the patch was converted to a diagonal direction, and as a result, the beam widths formed in each of the four sectors were added to create a wide beam width close to a hemisphere. The proposed antenna was studied for application to UAV(unmanned aerial vehicle), and the simulation test results confirmed that the 4.5 dBi beam width was 146.8°.

Analysis of the Radar Cross Section of an X-band Active Transponder (X-밴드 대역 능동 전파반사기 RCS 분석 연구)

  • Hwang, Ji-Hwan;Kwon, Soon-Gu;Won, Joong-Sun;Oh, Yi-Sok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.3
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    • pp.327-335
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    • 2011
  • A study on the RCS of a self-manufactured active transponder, which has a manually adjustable RCS, for SAR(Synthetic Aperture Radar) external calibration and image analysis at X-band is presented in this paper. The RCS of the active transponder was comparably analyzed using the lab-test and the COSMO-SkyMed SAR system, and also precisely analyzed the difference between the adjusted and estimated RCSs. A maximum RCS of the designed and manufactured active transponder is 60 dBsm. The active transponders with 60 dBsm and the adjusted RCS of 40 dBsm were measured using the single target calibration technique(STCT) and 2D target scanning technique(2DTST). And the extracted RCS using power-spill integration technique in a SAR image was compared with the measured RCS of active transponder. The comparison results show that the measured and extracted RCSs are 59.7 dBsm, 40.2 dBsm and 57.3 dBsm, 39.2 dBsm, respectively.