• Title/Summary/Keyword: Multi-beam

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Stochastic Radar Beam Scheduling Using Simulated Annealing (Simulated Annealing을 이용한 추계적 레이더 빔 스케줄링 알고리즘)

  • Roh, Ji-Eun;Ahn, Chang-Soo;Kim, Seon-Joo;Jang, Dae-Sung;Choi, Han-Lim
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.2
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    • pp.196-206
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    • 2012
  • AESA radar is able to instantaneously and adaptively position and control the beam, and such adaptive beam pointing of AESA radar enables to remarkably improve the multi-mission capability, compared with mechanically scanned array radar. AESA radar brings a new challenges, radar resource management(RRM), which is a technique efficiently allocating finite resources, such as energy and time to each task in an optimal and intelligent way. Especially radar beam scheduling is the most critical component for the success of RRM. In this paper, we proposed stochastic radar beam scheduling algorithm using simulated annealing(SA), and evaluated the performance on the multi-function radar scenario. As a result, we showed that our proposed algorithm is superior to previous dispatching rule based scheduling algorithm from the viewpoint of beam processing latency and the number of scheduled beams, with real time capability.

Underwater Telemetering by Ultrasonic Multi-Beam Transducer (Multi-Beam 초음파진동자의 수중원격제어에 관한 연구)

  • Choe, Han-Gyu;Sin, Hyeong-Il
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.27 no.1
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    • pp.31-40
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    • 1991
  • This paper described on the availability fo the underwater telemetering by the ulterasonic multi-beam system made as a trial to expand detectable range of the fish school. The ultrasonic multi-beam system consisted of four transducers which reconstructed with the existing net recorder. The experiment for the telemetering carried out in the set net fishing ground. The results obtained are summerized as follows: 1. The detectable distance of a target by the linear arrangement of four transducers increased according to the sea depth and the interval between transducers. 2. When the fish school in the entrance of set net was measured by linear arrangement of transducers it was entered in depth of 2.5~3.5m at near position of leader, and in depth of 3.5~4.5m at near position of door net. 3. The deviations of error between the actual position and the position by transducer in case of the target depth 1m, 1.5m, 2m were 5.9~27.1cm, 3.2~28.9cm, 3.5~25.8cm respectively, and 68.3% probability radius of them were 14.6cm, 17.7cm, 17.0cm respectively. 4. When the fish school in the fish court of set net was measured by plane arrangement of transducer it was entered toward the opposite direction of tide current. 5. The available distance of telemetering by the multi-beam transducer was 1.8km and the telemetering was possible to control everywhere in case of sea depth more than three meters.

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Estimation Method of Strain Distribution for Safety Monitoring of Multi-span Steel Beam Using FBG Sensor (FBG센서를 이용한 다경간 강재 보 구조물의 안전성 모니터링을 위한 변형률 분포 추정 기법)

  • Oh, Byung-Kwan;Lee, Ji-Hoon;Choi, Se-Woon;Park, Hyo-Seon;Kim, You-Sok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.1
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    • pp.138-149
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    • 2014
  • This study proposes an estimation method of strain distribution for multi-span steel beam structure under unspecific loading conditions. The estimation method in this paper employs the curve fitting using the least square method from measured strain data, not analytical method. To verify the proposed estimation method, a static loading test for multi-span steel beam on which distributed and concentrated loads act was conducted. The strain data for verification was measured by FBG sensors that have multiplexing technology. The analysis of the accuracy of strain estimation for distributed and concentrated loads and the errors by considering the number of measured points used in the estimation were conducted. In the maximum strain points, the strains could be estimated with the errors of 5.89% (loading step 1) and 6.26% (loading step 2). In case of decreasing the number of sensors, it was also confirmed that the errors increased (0.26~0.37%). Through the curve fitting method, it is possible to estimate the strain distribution (maximum strains and their locations) of multi-span beam for unspecific loads and go over the limit of the analytical estimation method which is suitable for specific distributed loads.

A study on the design of the laser marking system using galvanometer scanner (갈바노미터 스캐너를 이용한 레이저 마킹 시스템 설계 제작에 관한 연구)

  • 조태익;이건이
    • 제어로봇시스템학회:학술대회논문집
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    • 1986.10a
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    • pp.145-148
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    • 1986
  • To perform the marking on metal with high speed and non-contact using the laser beam of high energy, laser marking system is designed and fabricated applying the galvanometer scanner capable of high speed-precise beam positioning controlled by microprocessor. Laser is a Q-switched Nd:YAG producing multi-mode, wavelength, 1060nm. Optical system is composed of beam expander, scanning mirror and flat field lens. Consequently, the laser marking is satisfactorily achieved regardless of kinds of metal.

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Formation of PDP cell structure using Nd:YAG laser beam (Nd:YAG 레이저빔에 의한 PDP 방전셀의 구조 형성)

  • Ahn, Min-Young;Lee, Kyoung-Cheol;Lee, Hong-Kyu;Lee, Cheon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04a
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    • pp.129-132
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    • 2000
  • The PDP(Plasma Display Panel) barrier rib material on the glass substrate was patterned for fabrication of the PDP cell using Nd:YAG laser(1064 nm) which can generate the second(532 nm) and forth(266 nm) harmonic wave by HGM(harmonic generation modules). At a scan speed of 20 ${\mu}m/s$ with the second harmonic wave(532 nm) of Nd:YAG laser, the etching threshold laser fluence of the PDP material was 6.5 $mJ/cm^2$ and a sample(thickness = 180 ${\mu}m$) on the glass substrate was removed clearly at a laser fluence of 19.5 $mJ/cm^2$. In order to increase the throughput of the fabrication we divided a single-beam into multi-beams by using a metal mask between the sample and the focusing lens. As a result, 10 lines of PDP cell were formed by one laser beam scanning at a scan speed of 200 ${\mu}m/s$ and a laser fluence of 2.86 $J/cm^2$.

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Buckling analysis of tapered BDFGM nano-beam under variable axial compression resting on elastic medium

  • Heydari, Abbas;Shariati, Mahdi
    • Structural Engineering and Mechanics
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    • v.66 no.6
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    • pp.737-748
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    • 2018
  • The current study presents a new technique in the framework of the nonlocal elasticity theory for a comprehensive buckling analysis of Euler-Bernoulli nano-beams made up of bidirectional functionally graded material (BDFGM). The mechanical properties are considered by exponential and arbitrary variations for axial and transverse directions, respectively. The various circumstances including tapering, resting on two-parameter elastic foundation, step-wise or continuous variations of axial loading, various shapes of sections with various distribution laws of mechanical properties and various boundary conditions like the multi-span beams are taken into account. As far as we know, for the first time in the current work, the buckling analyses of BDFGM nano-beams are carried out under mentioned circumstances. The critical buckling loads and mode shapes are calculated by using energy method and a new technique based on calculus of variations and collocation method. Fast convergence and excellent agreement with the known data in literature, wherever possible, presents the efficiency of proposed technique. The effects of boundary conditions, material and taper constants, foundation moduli, variable axial compression and small-scale of nano-beam on the buckling loads and mode shapes are investigated. Moreover the analytical solutions, for the simpler cases are provided in appendices.

3D Depth Measurement System based on Parameter Calibration of the Mu1ti-Sensors (실거리 파라미터 교정식 복합센서 기반 3차원 거리측정 시스템)

  • Kim, Jong-Man;Kim, Won-Sop;Hwang, Jong-Sun;Kim, Yeong-Min
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.05a
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    • pp.125-129
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    • 2006
  • The analysis of the depth measurement system with multi-sensors (laser, camera, mirror) has been done and the parameter calibration technique has been proposed. In the proposed depth measurement system, the laser beam is reflected to the object by the rotating mirror and again the position of the laser beam is observed through the same mirror by the camera. The depth of the object pointed by the laser beam is computed depending on the pixel position on the CCD. There involved several number of internal and external parameters such as inter-pixel distance, focal length, position and orientation of the system components in the depth measurement error. In this paper, it is shown through the error sensitivity analysis of the parameters that the most important parameters in the sense of error sources are the angle of the laser beam and the inter pixel distance.

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Development of neutron time-of-flight measurement system for 1.7-MV tandem proton accelerator with lithium target

  • Lim, Soobin;Kim, Donghwan;Kang, Jin-Goo;Dang, Jeong-Jeung;Lee, Pilsoo;Kim, Geehyun;Chung, Kyoung-Jae;Hwang, Y.S.
    • Nuclear Engineering and Technology
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    • v.54 no.2
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    • pp.437-441
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    • 2022
  • In this study, we developed a neutron time-of-flight (nTOF) measurement system for a 1.7-MV tandem proton accelerator with a target covered with 300-nm-thick lithium (Li) layer. With implementation of beam chopping module after its ion source, the accelerator is configured to operate in pulsed-beam mode with a pulse width <50 ns at 20-kHz repetition rate. This enables the gamma flash-type nTOF measurement system to identify the neutron generated with 3-MeV proton beam energy. The nTOF system consists of a 30" cylindrical NaI(Tl) and four stilbene scintillation detectors. The NaI(Tl) scintillator is placed 50 cm from the Li target to measure the time of beam irradiation on the target, and the stilbene detectors are placed 2 and 2.4 m away to measure nTOF at each location. The nTOF system successfully measured the generated neutron energy at irradiated proton energies of 2.6 and 3.0 MeV with an average energy resolution of 15%.

An energy-based vibration model for beam bridges with multiple constraints

  • Huang, Shiping;Zhang, Huijian;Chen, Piaohua;Zhu, Yazhi;Zuazua, Enrique
    • Structural Engineering and Mechanics
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    • v.82 no.1
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    • pp.41-53
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    • 2022
  • We developed an accurate and simple vibration model to calculate the natural frequencies and their corresponding vibration modes for multi-span beam bridges with non-uniform cross-sections. A closed set of characteristic functions of a single-span beam was used to construct the vibration modes of the multi-span bridges, which were considered single-span beams with multiple constraints. To simplify the boundary conditions, the restraints were converted into spring constraints. Then the functional of the total energy has the same form as the penalty method. Compared to the conventional penalty method, the penalty coefficients in the proposed approach can be calculated directly, which can avoid the iteration process and convergence problem. The natural frequencies and corresponding vibration modes were obtained via the minimum total potential energy principle. By using the symmetry of the eigenfunctions or structure, the matrix size can be further reduced, which increases the computational efficiency of the proposed model. The accuracy and efficiency of the proposed approach were validated by the finite element method.