• Title/Summary/Keyword: 육각 배열

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A Study on Optimization of Structure for Hexagon Tile Sub-array Antenna System (Hexagon 타일 부배열 안테나 시스템 구조 최적화에 관한 연구)

  • Jung, Jinwoo;Pyo, Seongmin
    • Journal of IKEEE
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    • v.26 no.1
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    • pp.129-132
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    • 2022
  • In this paper, a technique for optimizing the sub-array system structure that can minimize the side lobe level of the phased-array antenna is proposed. Optimization of the proposed array antenna structure is to adjust the spacing between sub-arrays and sub-arrays by using a hexagonal array structure of one sub-array and a hexagonal sub-array for six hexagonal arrays, and thus the entire phased array antenna system of the radiation pattern was optimized. Compared to the 2-dimensional planar antenna system, the proposed technique maintains a gain of 24.3 dBi and a half-power beam-width of 8.46 degrees without change, and only reduces -3.4 dB and -6.5 dB in the x-axis and y-axis directions, respectively.

Fabrication of Hexagonally Assembled Gold Nonodots Based on Anodization of Aluminum (알루미늄 양극산화를 이용한 육각구조로 규칙적으로 배열된 금 나노구조 제조)

  • Lee, Joon Ho;Lee, Han Sub;Choi, Jinsub
    • Applied Chemistry for Engineering
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    • v.20 no.2
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    • pp.191-194
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    • 2009
  • Porous alumina prepared by anodization has been widely studied since it shows very regular nanostructures at inexpensive prices. In this article, porous alumina is obtained by anodization of aluminum in the oxalic acid. After the first formed oxide is selectively removed from the aluminum substrate, the hexagonal nanostructures on the fresh aluminum are converted to nanodots by the second anodization in boric acid. Nanodots are arrayed in the convex of the hexagonal nanostructures. The optimization condition for the fabrication of nanodots with a height of 20 nm is investigated in detail. Subsequently, a gold film is deposited on the nanodots, resulting in the formation of gold nanodots arrays which are probably interesting substrate for biosensor applications.

Prediction of Mechanical Property of Biomorphic Composites (Biomorphic C/SiC 복합재료의 기계적 물성 연구)

  • Jeong, Jae-Yeon;Woo, Kyeong-Sik;Lee, Dong-Ju;Hong, Soon-Hyung;Kim, Yun-Chul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.8
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    • pp.670-677
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    • 2012
  • In this paper, mechanical property of biomorphic C/SiC composite was calculated by unit cell analysis. The microstructural arrangements of carbonized pine and radiata pine which were impregnated with silicon, were idealized as square and hexagonal arrays. Unit cell was then defined and equivalent elastic constants were calculated. A single and double unit cell structures were considered. The effect of void distribution was also studied by monte carlo simulation.

Prediction of Non-linear Behavior of Flexible Matrix Composites (유연수지를 기지재료로 하는 복합재료의 비선형거동 예측)

  • 서영욱;우경식
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.10
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    • pp.24-31
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    • 2006
  • In this paper, mechanical behavior of unidirectional composites with flexible matrix was predicted by geometrical non-linear finite element analysis. Two typical idealized unit cells of square and hexagonal fiber arrays were modeled and these were subjected to different loadings. The stress-strain behavior of composites was predicted from which the effective properties were calculated. The hyperelasticity of polyurethane matrix was considered using Mooney-Rivlin model. In result, the stress-strain behavior of flexible composites shows non-linearity, especially it is remarkable under transverse normal and shear loading conditions. In this cases, there are great difference between square and hexagonal fiber array models.

Adaptive Beamforming System Based on Combined Array Antenna (혼합 배열 안테나 기반의 적응 빔형성 시스템)

  • Kim, Tae-Yun;Hwang, Suk-Seung
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.1
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    • pp.9-18
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    • 2021
  • The 5G communication system employs the millimeter wave with the extremely high frequency. Since the high frequency signal has the strong straightness, the beamforming technology based on the multiple base stations is required for services covering wide range. The beamformer needs the angle-of-arrival(AOA) information of the signal incident to the antenna, and it is generally estimated through the high resolution AOA estimation algorithm such as Multiple Signal Classification (MUSIC) or Estimation of Signal Parameters via Rotational Invariacne Technique (ESPRIT). Although various antenna array shapes can be employed for the beamformer, a single shape (square, circle, or hexagonal) is typically utilized. In this paper, we introduce a transmitting/receiving beamforming system based on the combined array antenna with square and circular shapes, which is proper to various frequency signals, and evaluate its performance. For evaluating the performance of the proposed beamforming system based on the combined array antenna, we implement the computer simulation employing various scenarios.

Friction Characteristics of Hexagonal Array Micro-scale Dimple Pattern by Density (Hexagonal Array Micro-Scale Dimple Pattern의 밀도에 따른 마찰특성)

  • Chae, Young-Hoon;Jang, Chung-Sun;Choi, Won-Sik
    • Tribology and Lubricants
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    • v.24 no.6
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    • pp.368-373
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    • 2008
  • This paper will investigate the friction characteristics of a 100m Hexagonal Array, Micro-scale Dimple Pattern, on bearing steel. These characteristics are researched by utilizing a pin-on-disk wear test machine, under various test conditions. The reduction of friction is a necessary requirement for the improved efficiency of this machine. As the speed increases, there is a decrease in the effect of the dimple of friction characteristic, with substantially little change to density. Conversely, as the load increases, the dimple pattern grows larger, resulting in a difference in the texture of these two components. At a dimple density of 10% the friction characteristic is easily demonstrated, with a consistent change in both speed and load.

Surface characteristics change of natural crystalline graphite powders by adsorption (유기물 흡착에 의한 인상흑연 분체의 표면특성변환 연구)

  • 김병곤;최상근;정헌생;이재장
    • Proceedings of the KSEEG Conference
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    • 2001.04a
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    • pp.308-310
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    • 2001
  • 유기물질이 오랜 기간동안 고온 고압하에서 탄화작용을 받아 생성된 천연흑연은 단위구조가 탄소육각망평면(炭素六角網平面)이 평행하게 배열된 층상으로 전기전도도 및 윤할성이 우수하나 소수성이 매우 강하며 표변화학적 특성이 거의 없기 때문에 다른 물질과 표면흡착이 매우 어려운 물질이다. 따라서 본 연구에서는 흑연의 표면특성을 변화시키고자 유기물(ABDM)을 흡착시키고 표면흡착 매커니즘 및 표면특성을 해석하였다. 흑연 입자 표면 위의 ABDM흡착은 두 단계의 서로 다른 게에서 이루어졌다. 첫 번째 단계는 흡착 초기 흑연입자와 ABDM의 표면전위 특성차이에 의한 1차 흡착으로 흑연표면 소수성이 더욱 증가하는 상태이고, 두 번째 단계는 1차 흡착된 ABDM 과 용액중의 ABDM chain 상호간의 steric 작용에 의한 2차 흡착이었다. 2차 흡착이 완료된 흑연입자 표면은 ABDM 이중층을 형성하게 되고 이에 따라 흑연의 표면전위 특성을 변화시킬 수 있었다.

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Effects of Fiber Arrangements on Stress Distributions over the Transverse Cross Section of Unidirectionally Continuous Fiber-reinforced Composites (단방향 연속 섬유 복합재 횡단면에서 섬유 배열에 따른 응력 분포 변화)

  • Choi, Soohoon;Ji, Wooseok
    • Composites Research
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    • v.33 no.1
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    • pp.30-37
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    • 2020
  • Stress distributions dependent on fiber arrangements are studied using the two-dimensional representative volume element (RVE) model for uni-directionally continuous fiber-reinforced composites subjected to transverse tensile loading. It is easily expected that the stresses around the fibers are concentrated mainly due to the stiffness mismatch between the fiber and matrix materials. In this presentation, it is shown that the stresses are not always increased although the distance between two fibers is shortened. The 2D RVE models, originally having a regular hexagonal fiber array, is utilized to study the effect of the fiber locations on the stress distributions. As the central fiber is relocated, the stress distributions around the fiber are obtained through finite element analysis. It is found that the stresses around the fiber are strongly dependent on the fiber distance as well as the angle between the loading direction and the line connecting two fibers.

Added Mass of Regular Polygonal Cylinders with Fluid Gap (유체 의 틈 이 있는 정다각형 실린더 의 부가질량)

  • 김만회;김문언;조형석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.1
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    • pp.56-63
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    • 1985
  • Methods for evaluating the added masses of square and hexagonal structures with fluid gap are presented. For a sufficiently small fluid gap, an analytical expression for the added mass is found using the method of matched asymptotic expansion. Experimental data and numerical results using finite element method are also obtained for various sizes of fluid gap. It is shown that added masses increase in inverse proportion to the fluid gap as it becomes smaller. Experimental data, theoretical and numerical results are in good agreement.

Optimization of Parallel-Hole Collimator for Small Gamma Camera Based on Pixellated Crystal Array (배열형 섬광결정을 이용한 소형 감마카메라의 평행구멍형 조준기 최적화 연구)

  • Chung, Yong-Hyun;Beak, Cheol-Ha;Lee, Seung-Jae;Park, Jin-Hyung
    • Progress in Medical Physics
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    • v.19 no.4
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    • pp.291-297
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    • 2008
  • The purpose of this study is to optimize a parallel-hole collimator for small gamma camera having the pixellated crystal array and evaluate the effect of crystal-collimator misalignment on the image quality using a simulation tool GATE (Geant4 Application for Tomographic Emission). The spatial resolution and sensitivity were measured for the various size of hexagonal-hole and matched square-hole collimators with a Tc-99m point source and the uniformity of flood image was estimated as a function of the angle between crystal array and collimator by misalignment. The results showed that the spatial resolution and sensitivity were greatly improved by using the matched collimator and the uniformity was reduced by crystal-collimator misalignment.

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