• Title/Summary/Keyword: Normal element

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The Finite element with Normal Rotational Degree Freedoms (유한요소의 Normal rotation 연구)

  • Cho, Soon-Bo
    • Journal of Korean Association for Spatial Structures
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    • v.4 no.4 s.14
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    • pp.85-89
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    • 2004
  • A frame element embedded normal to a shear wall or slab (shell element) is common in the structural systems. In that case there is a need for a membrane or shell element to have a normal rotation degree of freedom at each node in order to have a good result of stresses. Even if Many other people studied this area, All man, Cook and Sabir are representative investigators in this area. In this research paper, Sabir's methods of vertex rotation stiffness matrix in a membrane element are studied. New stiffness of vertex rotation are proposed by taking advantage of beam stiffness theory. Rectangular elements stiffness with rotational degree of freedom are compared in accuracy ratio each other.

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An Efficient Algorithm for Computing Multiplicative Inverses in GF($2^m$) Using Optimal Normal Bases (최적 정규기저를 이용한 효율적인 역수연산 알고리즘에 관한 연구)

  • 윤석웅;유형선
    • The Journal of Society for e-Business Studies
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    • v.8 no.1
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    • pp.113-119
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    • 2003
  • This paper proposes a new multiplicative inverse algorithm for the Galois field GF (2/sup m/) whose elements are represented by optimal normal basis type Ⅱ. One advantage of the normal basis is that the squaring of an element is computed by a cyclic shift of the binary representation. A normal basis element is always possible to rewrite canonical basis form. The proposed algorithm combines normal basis and canonical basis. The new algorithm is more suitable for implementation than conventional algorithm.

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A Novel Electrochemical Method for Sensitive Detection of Melamine in Infant Formula and Milk using Ascorbic Acid as Recognition Element

  • Li, Junhua;Kuang, Daizhi;Feng, Yonglan;Zhang, Fuxing;Xu, Zhifeng;Liu, Mengqin
    • Bulletin of the Korean Chemical Society
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    • v.33 no.8
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    • pp.2499-2507
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    • 2012
  • A novel and convenient electrochemical method has been developed for sensitive determination of melamine (MEL) using ascorbic acid (AA) as the recognition element. The working electrode employed in this method was modified with the nanocomposite of hydroxyapatite/carbon nanotubes to enhance the current signal of recognition element. The interaction between MEL and AA was investigated by fourier transform infrared spectroscopy and cyclic voltammetry, and the experimental results indicated that hydrogen bonding was formed between MEL and AA. Because of the existing hydrogen bonding and electrostatic interaction, the anodic peak current of AA was decreased obviously while the non-electroactive MEL added in. It illustrated that the MEL acted as an inhibitor to the oxidation of AA and the decreasing signals can be used to detect MEL. Under the optimal conditions, the decrease in anodic peak current of AA was proportional to the MEL concentrations ranging from 10 to 350 nM, with a detection limit of 1.5 nM. Finally this newly-proposed method was successfully employed to detect MEL in infant formula and milk, and good recovery was achieved.

Exterior Acoustic Holography Reconstruction of a Tuning Fork Using Inverse Non-singular BEM

  • Jarng, Soon-Suck
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.1E
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    • pp.11-18
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    • 2003
  • Non-singular boundary element method (BEM) codes are developed in acoustics application. The BEM code is then used to calculate unknown boundary surface normal displacements and surface pressures from known exterior near field pressures. And then the calculated surface normal displacements and surface pressures are again applied to the BEM in forward in order to calculate reconstructed field pressures. The initial exterior near field pressures are very well agreed with the later reconstructed field pressures. Only the same number of boundary surface nodes (1178) are used for the initial exterior pressures which are at first calculated by Finite Element Method (FEM) and BEM. Pseudo-inverse technique is, used for the calculation of the unknown boundary surface normal displacements. The structural object is a tuning fork with 128.4 ㎐ resonant. The boundary element is a quadratic hexahedral element (eight nodes per element).

Exterior Acoustic Holography Reconstruction of a Tuning Fork using Inverse Non-singular BEM (역 비고유치 BEM을 사용한 소리 굽쇠의 외부 음향 홀로그래픽 재현)

  • Jarng, Soon-Suck;Lee, Je-Hyeong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.306-311
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    • 2002
  • Non-singular boundary element method (BEM) codes are developed in acoustics application. The BEM code is then used to calculate unknown boundary surface normal displacements and surface pressures from known exterior near Held pressures. And then the calculated surface normal displacements and surface pressures are again applied to the BEM in forward in order to calculate reconstructed field pressures. The initial exterior near field pressures are very well agreed with the later reconstructed field pressures. Only the same number of boundary surface nodes (1178) are used far the initial exterior pressures which are initially calculated by Finite Element Method (FEM) and BEM. Pseudo-inverse technique is used for the calculation of the unknown boundary surface normal displacements. The structural object is a tuning fork with 128.4 Hz resonant. The boundary element is a quadratic hexahedral element (eight nodes per element).

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A Study on a Wideband Helical Antenna for Mobile Handset using Parasitic Element Effect (기생소자 효과를 이용한 이동 단말기용 광대역 헬리컬 안테나 연구)

  • 성원모;양묘근;전용승;이치우;박진희;최학근
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.9
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    • pp.899-903
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    • 2003
  • In this paper, a wide band helical antenna for mobile handset using parasitic element effect has been investigated. To obtain the effect of parasitic element, we utilized the cylindrical conductor which is not feed. As thickness of cylindrical conductor is increasing, second and third resonance frequency become abruptly variable. In case of that 4.5mm diameter parasitic element cylindrical conductor is inserted, normal mode helical antenna obtained bandwidth of around 900 MHz on the limit of R. L., - 5 dB.

Automatic Quadrilateral Element Mesh Generation Using Boundary Normal Offsetting In Various Two Dimensional Objects (다양한 2차원 형상에서의 외부 경계 절점 오프셋 방법을 이용한 자동 사각 요소 및 요소망 생성)

  • 김도헌;양현익
    • Korean Journal of Computational Design and Engineering
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    • v.8 no.4
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    • pp.270-277
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    • 2003
  • In two dimensional mechanical design analysis, quadrilateral element mesh is preferred because it provides more accurate result than triangular element mesh. However, automation of quadrilateral element mesh generation is much more complex because of its geometrical complexities. In this study, an automatic quadrilateral element mesh generation algorithm based on the boundary normal offsetting method and the boundary decomposition method is developed. In so doing, nodes are automatically placed using the boundary normal offsetting method and the decomposition method is applied to decompose the designed domain into a set of convex subdomains. The generated elements are improved by relocation of the existing nodes based on the four criteria - uniformity, aspect ratio, skewness and taper degree. The developed algorithm requires minimal user inputs such as boundary data and the distance between nodes.

Finite Element Simulation of Axisymmetric Sheet Hydroforming Processes (축대칭 박판 액압 성형 공정의 유한요소 시뮬레이션)

  • 구본영;김용석;금영탁
    • Transactions of Materials Processing
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    • v.9 no.6
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    • pp.590-597
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    • 2000
  • A finite element formulation lot the simulation of axisymmetric sheet hydroforming is proposed, and an implicit program is coded. In order to describe normal anisotropy of steel sheet, Hill's non-quadratic yield function (Hill, 1979) is employed. Frictional contacts among sheet surface, rigid tool surface, and flexible hydrostatic pressure are considered using mesh normal vectors based on finite element of the sheet. Applied hydraulic pressure is also considered as a function of forming rate and time and treated as an external loading. The complete set of the governing relations comprising equilibrium and interfacial equations is approximately linearized for Newton-Raphson algorithm. In order to verify the validity of the developed finite element formulation, the axisymmetric bulge test is simulated. Simulation results are compared with other FEM results and experimental measurements and showed good agreements. In axisymmetric hydroforming processes of a disk cover, formability changes are observed according to the hydraulic pressure curve changes.

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FINITE VOLUME ELEMENT METHODS FOR NONLINEAR PARABOLIC PROBLEMS

  • LI, QIAN;LIU, ZHONGYAN
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.6 no.2
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    • pp.85-97
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    • 2002
  • In this paper, finite volume element methods for nonlinear parabolic problems are proposed and analyzed. Optimal order error estimates in $W^{1,p}$ and $L_p$ are derived for $2{\leq}p{\leq}{\infty}$. In addition, superconvergence for the error between the approximation solution and the generalized elliptic projection of the exact solution (or and the finite element solution) is also obtained.

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Development of the Direct Boundary Element Method for Thin Bodies with General bBundary Conditions (일반 경계 조건을 가진 얇은 물체에 대한 직접 경계 요소법의 개발)

  • 이강덕;이덕주
    • Journal of KSNVE
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    • v.7 no.6
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    • pp.975-984
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    • 1997
  • A direct boundary element method (DBEM) is developed for thin bodies whose surfaces are rigid or compliant. The Helmholtz integral equation and its normal derivative integral equation are adoped simultaneously to calculate the pressure on both sides of the thin body, instead of the jump values across it, to account for the different surface conditions of each side. Unlike the usual assumption, the normal velocity is assumed to be discontinuous across the thin body. In this approach, only the neutral surface of the thin body has to be discretized. The method is validated by comparison with analytic and/or numerical results for acoustic scattering and radiation from several surface conditions of the thin body; the surfaces are rigid when stationary or vibrating, and part of the interior surface is lined with a sound-absoring material.

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