• Title/Summary/Keyword: moment matrix

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Dielectric Cover effect of Rectangular Microstrip Patch Antenna on Uniaxial Substrates with Airgap (공기 갭을 갖는 일축성 매질 위에 마이크로스트립 패치 안테나의 덮개층 영향)

  • Yoon, Joong-Han;An, Gyoo-Chul;Kwak, Kyung-Sup
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.38 no.9
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    • pp.29-39
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    • 2001
  • Dielectric cover effect of rectangular microstrip patch antenna on uniaxial substrates with airgap are studied. First, we derive Dyadic Green function for selected anisotropic material by constitutive relation and then formulate integral equations of electric fields using Fourier transform in space region. Using Galerkin's moment method, we discretize the electric field integral equations into the matrix form and select sinusoidal functions as basis functions. We verify the validity of numerical results and compare the results with existing ones in showing a good agreement between them. When the dielectric cover thickness is varied, the resonant frequencies and input impedances in the variation of air gap, patch length and thickness and permittivity of superstrate are presented and analyzed.

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Autopilot Design of an Autonomous Underwater Vehicle Using Robust Control

  • Jung, Keum-Young;Kim, In-Soo;Yang, Seung-Yun;Lee, Man-Hyung
    • Transactions on Control, Automation and Systems Engineering
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    • v.4 no.4
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    • pp.264-269
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    • 2002
  • In this paper, Η$_{\infty}$ depth and course controller of an AUV(Autonomous Underwater Vehicle) using Η$_{\infty}$ servo control is proposed. The Η$_{\infty}$ servo problem is formulated to design the controllers satisfying a robust tracking property with modeling errors and disturbances. The solution of the Η$_{\infty}$ servo problem is as fellows: first, this problem is modified as an Η$_{\infty}$ control problem for the generalized plant that includes a reference input mode, and then a sub-optimal solution that satisfies a given performance criteria is calculated by LMI(Linear Matrix Inequality) approach. The Η$_{\infty}$ depth and course controller are designed to satisfy with the robust stability about the modeling error generated from the perturbation of the hydrodynamic coefficients and the robust tracking property under disturbances(wave force, wave moment, tide). The performances of the designed controllers are evaluated with computer simulations, and finally these simulation results show the usefulness and application of the proposed Η$_{\infty}$ depth and course control system.

$H_\infty$ Depth Controller Design for Underwater Vehicles (수중운동체의 $H_\infty$ 심도제어기 설계)

  • 이만형;정금영;김인수;주효남;양승윤
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.5
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    • pp.345-355
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    • 2000
  • In this paper, the depth controller of an underwater vehicle based on an $H_\infty$ servo control is designed for the depth keeping of the underwater vehicle under wave disturbances. The depth controller is designed in the form of the $H_\infty$ servo controller, which has robust tracking property, and an $H_\infty$ servo problem is considered for the $H_\infty$ servo controller design. In order to solve the $H_\infty$ servo problem for the underwater vehicle, this problem is modified as an $H_\infty$ control problem for the generalized plant that includes a reference input mode, and a suboptimal solution that satisfies a given performance criteria is calculated with the LMI (Linear Matrix Inequality) approach. The $H_\infty$ servo controller is designed to have robust stability about the perturbation of the parameters of the underwater vehicle and the robust tracking property of the underwater vehicle depth under wave force and moment disturbances. The performance, robustness about the uncertainties, and depth tracking property, of the designed depth controller is evaluated by computer simulation, and finally these simulation results show the usefulness and applicability of the proposed $H_\infty$ depth control system.

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Depth and Course Controller Design of Autonomous Underwater Vehicles using H$_\infty$ Servo Control (H$_\infty$ 서보제어를 이용한 무인 수중운동체의 심도 및 방향제어기 설계)

  • 김인수;정금영;양승윤;조상훈;정찬희;이만형
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.215-215
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    • 2000
  • In this paper, depth and course controllers of autonomous underwater vehicles using H$_{\infty}$ servo control are proposed. An H$_{\infty}$ servo problem is formulated to design the controllers satisfying a robust tracking property with modeling errors and disturbances. The solution of the H$_{\infty}$ servo problem is as follows: first, this problem is modified as an H$_{\infty}$ control problem for the generalized plant that includes a reference input mode, and then a sub-optimal solution that satisfies a given performance criteria is calculated by LMI(Linear Matrix Inequality) approach. The H$_{\infty}$ depth and course controllers ate designed to satisfy with the robust stability about the modeling error generated from the perturbation of the hydrodynamic coefficients and the robust tracking property under disturbances(wave force, wave moment, tide). The performances(the robustness to the uncertainties, depth and course tracking properties) of the designed controllers are evaluated with computer simulations, and finally these simulation results show the usefulness and application of the proposed H$_{\infty}$ depth and course control systems.

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Penetration Fracture Characteristics of Orthotropic CFRP Laminates Shells according to Curvature (곡률이 다른 직교이방성 CFRP 적층쉘의 관통파괴특성)

  • Yang, Yong Jun;Pyeon, Seok Beom;Cha, Cheon Seok;Yang, In Young
    • Journal of the Korean Society of Safety
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    • v.31 no.6
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    • pp.6-11
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    • 2016
  • CFRP composite laminates are widely used as structural materials for airplanes, automobile and aerospace vehicles because of their high strength and stiffness. This study aims to examine an effect of curvature on the penetration fracture characteristic of an orthotropic composite laminated shell. For the purpose, we manufactured orthotropic CFRP shell specimen with different curvatures, and conducted a penetration test using an air-gun. Those specimens were prepared to varied curvature radius(${\infty}$, 200mm, 150mm and 100mm)and were stacked to $[O^{\circ}{_3}/90^{\circ}{_3}]_s$. When the specimen is subjected to transverse impact by a steel sphere(${\Phi}10$), the velocity of steel sphere was measured both before and after impact by determining the time for it to pass two ball-screen sensors located a known distance apart. As the curvature increases, the absorption energy and the critical penetration energy increased linearly because the resistance to the bending moment. Patterns of cracks caused by the penetration of CFRP laminated shells included fiber breakage, lamina fracture, matrix crack interlaminar crack and intralaminar crack.

MULTISPECTRAL IMAGING APPLICATION FOR FOOD INSPECTION

  • Park, Bosoon;Y.R.Chen
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 1996.06c
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    • pp.755-764
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    • 1996
  • A multispectral imaging system with selected wavelength optical filter was demonstrated feasible for food safety inspection. Intensified multispectral images of carcasses were obtained with visible/near-infrared optical filters(542-847 nm wavelengths) and analyzed. The analysis of textural features based on co-occurrence matrices was conducted to determine the feasibility of a multispectral image analyses for discriminating unwholesome poultry carcasses from wholesome carcasses. The mean angular second moment of the wholesome carcasses scanned at 542 nm wavelength was lower than that of septicemic (P$\leq$0.0005) and cadaver(P$\leq$0.0005) carcasses. On the other hand, for the carcasses scanned at 700nm wavelength , the feature values of septicemic and cadaver carcasses were significantly (P$\leq$0.0005) different from wholesome carcasses. The discriminant functions for classifying poultry carcasses into three classes (wholesome, septicemic , cadaver) were developed using linear and quadr tic covariance matrix analysis method. The accuracy of the quadratic discriminant models, expressed in rates of correct classification, were over 90% for the classification of wholesome, septicemic, and cadaver carcasses when textural features from the spectral images scanned at the wavelength of 542 and 700nm were utilized.

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A Robust Content-Based Image Retrieval Technique for Distorted Query Image (변형된 질의 영상에 강한 내용 기반 영상 검색 기법)

  • 김익재;이제호;권용무;박상희
    • Journal of Broadcast Engineering
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    • v.2 no.1
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    • pp.74-83
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    • 1997
  • We have proposed a composite feature measure which combines the color and shape features of an image for image retrieval. We improved the performance of retrieval based on the efficient color quantization using the Lloyd-Max quanizer and on the Histogram matrix matching method which considers the spatial correlation of quantized color group. We also supplemented the color information using shape information with the Improved Moment Invarlants. We have tested our technique on Image database consisting of 200 actual trademark images. Our experimental results showed that our approach improved the performance compared to the previous method under the various situations such as rotation images, translation images, noise added images, gamma corrected images and so on. The efficiency of retrieval is found to be very high and experimental results are

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Dynamic Analysis of Spindle Supported by Multiple Bearings of Different Types (복합베어링으로 지지된 스핀들의 동적 해석)

  • Tong, Van-Canh;Bae, Gyu-Hyun;Hong, Seong-Wook
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.2
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    • pp.117-125
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    • 2015
  • This paper presents a dynamic modeling method for the indeterminate spindle-bearing system supported by multiple bearings of different types. A spindle-bearing system supported by ball and cylindrical roller bearings is considered. The de Mul's bearing model is extended for calculating ball and cylindrical roller bearing stiffness matrices with inclusion of centrifugal force and gyroscopic moment. The dependence between spindle shaft reaction forces and bearing stiffness is effectively resolved using an iterative approach. The spindle rotor dynamics is established with the Timoshenko beam theory based finite elements. The spindle reaction forces, bearings stiffness and spindle natural frequencies are obtained with taking into account spindle radial load, ball bearing axial preload and rotational speed effects. The developed method is verified by comparing the simulation results with those from a commercial program.

A Study on Connection Ductility of Steel Structures Subjected to Monotonic Loading (단조하중을 받는 철골구조물의 접합부 연성도에 관한 연구)

  • Kang, Suk-Bong;Kim, Jin-Hyoung
    • Journal of Korean Society of Steel Construction
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    • v.12 no.4 s.47
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    • pp.375-385
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    • 2000
  • The required connection ductility has been evaluated, considering geometric, material and connection nonlinearity, for 6-story unbraced and 20-story braced steel structures subjected to ultimate lateral load. For material nonlinearity, section moment-curvature relationship and member stiffness matrix have been derived utilizing fiber model and linear flexibility distribution model. In 6-story structure with semi-rigid connections for rigid connection, the required connection ductility is less than that for rigid connection. In 20-story structure, the required connection ductility for semi-rigid connection is almost the same as that for shear connection and the required ductility for rigid connection is larger than that for semi-rigid or shear connection.

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A Multiresolution Wavelet Scattering Analysis of Microstrip Patch antennas (마이크로스트립 패치 안테나의 다중 분해능 웨이블릿 산란해석법)

  • 강병용;주세훈;빈영부;김형훈;김형동
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.5
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    • pp.640-647
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    • 1998
  • Microstrip patch antennas are analyzed by a multiresolution wavelet method. The spectral Green's dyad of the structure is obtained and its joint spatial-spectral domain representations are presented. Based on the joint spatial-spectral domain representation, we show that the spectral-domain wavelets are useful in the analysis of this problem. We obtain the matrix equations of the integral equations of this Green's dyad by using the method of moment(MoM), and efficiently solve the problem using the spectral domain wavelet transform concepts in conjuction with the conjugate gradient method. The results for a single-layered square patch are compared with those of conventional MoM and CG-FFT.

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