• Title/Summary/Keyword: 십자형

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Forming Limit of AZ31B Magnesium Alloy Sheet in the Deep Drawing with Cross Shaped Die (십자 형상 금형의 디프 드로잉에서 AZ31B 마그네슘 합금판재의 성형 한계)

  • Hwang, S.H.;Choi, S.C.;Kim, H.Y.;Kim, H.J.;Hong, S.M.;Shin, Y.S.;Lee, G.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.374-377
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    • 2008
  • Magnesium alloy sheets are usually formed at temperatures between $150^{\circ}C$and $300^{\circ}C$ because of their poor formability at room temperature. In the present study, the formability of AZ31B magnesium alloy sheets was investigated by the analytical and experimental approaches. First, tensile tests and the limit dome height test were carried out at elevated temperatures to get the mechanical properties and forming limit diagram, respectively. And then deep drawing of cross shaped die was tried to get the minimum corner radius and forming limit at specific temperature. Blank shape, punch velocity, minimum corner radius, fillet size, etc, were determined by finite element analysis physical try-outs. Especially, optimum punch and die temperature were suggested through the temperature-deformation analysis using Pam-stamp.

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Transmission Cross Section of the Small Aperture in an Infinite Conducting Plane (도체 평판에서 소형 개구의 투과 단면적)

  • Ko, Ji-Hwan;Park, Soon-Woo;Cho, Young-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.30 no.4
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    • pp.300-306
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    • 2019
  • Transmission cross section(TCS) is described analytically as $2G{\lambda}^2/4{\pi}$ irrespective of the aperture shapes for various transmission resonant apertures, such as small ridged circular or H-shaped, U-shaped, or Jerusalem cross-shaped apertures in an infinite thin conducting plane. The proposed expression is validated by comparison with the numerical results obtained from the method of moments(MOM). The TCS characteristics of the transmission resonant cavity structure in a thick conducting plane are also studied and the equivalence between the two small aperture structures is reported from the viewpoint of transmission efficiency.

A Low Profile Dual-Microstripline-Fed 4-Arrayed Meander Monopole Antenna (소형 2중-급전 4-배열 미앤더 모노폴 안테나)

  • Jang, Yong-Woong;Lee, Sang-Woo
    • Journal of Broadcast Engineering
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    • v.23 no.6
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    • pp.925-930
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    • 2018
  • In this paper, we present a low profile dual-microstripline-fed double 4-arrayed meander monopole antenna with a cross-type element back by separated four-segments mesh-type reflector. The cross-type element and separated four-segments mesh-type reflector leads to enhance radiation patterns and antenna gain characteristics. The measurement value of the proposed antenna show that it has dipole-like radiation pattern characteristics. The experimental peak gain of fabricated antenna is about 2.89 dBi, which presents relatively high gain characteristics for a low profile(small-size) one. This antenna can be applied mobile RFID(radio frequency identification) readers, small medical instruments, broadcasting and home-networking operations, and other low profile high-gain systems.

Application of LFM Reverberation Suppression Using Difference of Singular Values in the Underwater Obstacle Detection (수중 장애물 탐지에서의 특이 값 차이를 이용한 LFM 잔향 감소 기법 적용 연구)

  • Lee, Hyung-Soo;Kwon, Bum-Soo;Cho, Chom-Gun;Lee, Kyun-Kyung
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.8
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    • pp.755-760
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    • 2009
  • In this paper, we apply a reverberation suppression method using difference of singular values to improve the short-distance underwater obstacle detection probability in reverberation environment induced by a linear frequency modulation signal. The reverberation suppression method using difference of singular values suppresses LFM reverberation based on subtracting the singular values for a reference beam, assumed to contain only the reverberation, from those for the current beam of interest, assumed to contain the reverberation and target echo. For the validation, the reverberation suppression method using difference of singular values is applied to real oceanic data, which are acquired using the cross type array.

Development of an SIS(Superconductor-Insulator-Superconductor) Junction Mixer over 120∼180 GHz Band (120∼180 GHz 대역 SIS (Superconductor-Insulator-Superconductor) 접합 믹서의 개발)

  • Chung, Moon-Hee;Lee, Changhoon;Kim, Kwang-Dong;Kim, Hyo-Ryoung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.8
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    • pp.737-743
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    • 2004
  • A fixed-tuned SIS(Superconductor-Insulator-Superconductor) mixer across 120∼180 GHz band has been developed. This mixer employs an SIS chip fabricated by Nobeyama radio observatory which consists of a series array of 6 Nb/Al-Al$_2$O$_3$/Nb junctions in a microstrip line on a fused quartz substrate. The SIS chip is placed at the center of the half-height waveguide mixer mount to have a good incoming signal coupling over the whole frequency band. No mechanical tuner was used in the SIS mixer and the RF signal and local oscillator power are injected to the mixer via a cooled cross-guide coupler. In order to prevent the IF signal loss, the If output impedance of the SIS mixer was matched to the 50 $\Omega$ input impedance of the IF chain. Measured double sideband noise temperatures of a receiver using the SIS mixer are 32∼131 K over 120∼180 GHz band. The developed SIS mixer is now in use for radio astronomical observations on the TRAO 14 m radio telescope.

Welding Characteristics of 400MPa Grade Hot Rolled H-beam(SHN400) for Building Structure (400MPa급 건축구조용 열간압연 H형강(SHN400)의 용접특성)

  • Kim, Hee-Dong;Yang, Jae-Geun;Lee, Eun-Taik;Kim, Woo-Bum;Oh, Young-Suk
    • Journal of Korean Society of Steel Construction
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    • v.24 no.1
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    • pp.129-136
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    • 2012
  • This study seeks to evaluate the welding characteristics of SHN400 steel, which is suitable for the steel material used in building structures in KS. For this purpose, the Y-groove weld crack test and hardness, tensile, bending, cross tensile, and charpy V notch tests at the welding point were conducted with specimens taken from the highest, the thickest and the commonly used H-beams for girder or beam members. Each test was conducted under the KS test conditions. All tests results satisfied the requirements of KS and the welding requirements for the proper inelastic behavior of structure, indicating that SHN400 can be used for the building structure as a structural material.

Behavior of Concrete-Filled Tube Column to H-Beam Connections with External Stiffeners and Reinforcing Bar (외부스티프너와 철근으로 보강한 CFT 기둥-H형강 보 접합부의 거동)

  • Kang, Chang-Hoon;Shin, Kyung-Jae;Oh, Young-Suk;Moon, Tae-Sup
    • Journal of Korean Society of Steel Construction
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    • v.12 no.1 s.44
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    • pp.55-63
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    • 2000
  • This paper is a study on the behavior of Concrete-Filled Square Tubular(CFST) column to H-beam connections reinforced with external stiffeners and reinforcing bar. The cyclic loading tests of 5 test specimens were carried out. The main Parameters are as follows; 1)the length of the stiffener: 200mm, 250mm, 2)the diameter of reinforcing bar: HD16, 19. The results of the researches demonstrate that the increase of the stiffener length was more effective than the increase of the area of reinforcing bar in the point of both strength and stiffness. By reinforcing external stiffeners, stable hysteretic behavior was shown and plastic hinge was formed on the beam flange. Cold-formed tube sections should be used carefully to avoid the welding fracture at the round corners of section, and the proposed welding methods are suitable for this connections.

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Design of Flexible Reconfigurable Frequency Selective Surface for X-Band Applications (유연한 구조를 갖는 X-Band 재구성 주파수 선택구조 설계)

  • Lee, In-Gon;Park, Chan-Sun;Yook, Jong-Gwan;Park, Yong-Bae;Chun, Heung-Jae;Kim, Yoon-Jae;Hong, Ic-Pyo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.1
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    • pp.80-83
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    • 2017
  • In this paper, the X-band reconfigurable frequency selective surface having flexible geometry was proposed. The proposed RFSS is composed of patterns of cross-shaped loop with inductive stub, which can control the frequency response for C-Band and X-band by ON/OFF state of PIN diode. To minimize the parasitic effect and to obtain the high level of isolation between the unit cell of FSS and the bias circuit, we designed the grid type bias line on bottom layer through via hole. The measured transmission characteristics show good agreement with the simulation results and good stability of frequency response for different incident angles and curvatures of surface.

Preparation of Electronic Paper using $TiO_2$ Nanoparticles ($TiO_2$ 나노입자를 이용한 전자종이 제조)

  • Lee, Nam-Hee;Kim, Joong-Hee;Hong, Wan-Sik;Jang, Moon-Ik;Ahn, Jin-Ho;Hwang, Jong-Sun;Kim, Sun-Jae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.97-102
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    • 2004
  • 용액 중에서 나노입자의 전기영동 특성을 이용한 전자종이용 잉크 제조를 위해 $TiO_2$ 나노입자를 저유전율 용매인 cyclohexane에 혼합한 후 용매와 용질의 비중차를 줄이기 위해 분말 상 polyethylen을 첨가하여 high energy milling의 방법으로 입자분쇄와 동시에 입자 표면에 고분자 풍을 코팅하였다. 용액내의 입자 분산성 향상과 용매 착색을 위하여 계면활성제와 oil-blue N을 첨가한 후 전자종이용 잉크를 제조하여 측정한 제타 전위 결과 cyclohexane 내에서 $TiO_2$의 제타전위는 -40mV 정도였으나 polyethylene으로 코팅한 후 계면활성제를 첨가하였을 경우 최대 -110mV 이상의 높은 값을 나타내었다. 실제 디스플레이 특성을 평가하기 위해 포토리소그래피를 이용하여 3인치 크기의 ITO glass 위에 $10{\mu}m$의 크기를 갖는 십자형의 격벽을 $40{\mu}m$의 높이로 균일하게 형성한 후 합성된 전자잉크로 주입하여 상부전극과 하부전극사이에 UV 경화제를 도포하여 UV 접합을 실시하였다. 격벽 내에서 입자의 mobility를 측정하여 환산된 전자잉크의 응답속도는 0.1cm/sec로 측정되었으나, 전기영동시 입자들의 움직임에 따른 반사광의 파형을 측정한 경우 0.07cm/sec의 응답속도를 나타내었다.

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DOA(Direction of Arrival) Estimation based Beamforming technique for VBeam Reception Performance Enhancement (VBeam 수신 성능 개선을 위한 입사각 추정 기반의 빔형성 알고리즘 연구)

  • Lee, Jae-Eun;Shim, Tae-Bo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.47 no.5
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    • pp.212-221
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    • 2010
  • The bubbles could be created from multiple source in the surface of ocean. The bubbles which are created like this affect to the intensity and the sound speed of acoustic wave which are used from the ocean. From the research, it observed Reverberation from the sea surface, using Vbeam transmission and reception equipment that was a cross-shaped Array, from 2008 July 2nd to July 3rd at 4Km from the East Sea Mookho port. It is difficult to analyze data because the received signal has ambient noise and occurrence ISI(Inter Symbol Interference) for multipath. This paper remove that ambient noise and ISI using the directions of arrival beamforming and the filter and sum beamforming. After beamforming, a following DFE(Decision Feedback Equalizer) removes the remaining multipath components. Experimental results show that the proposed technique reduce the errors caused by ISI.