• Title/Summary/Keyword: Finite Field Division

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Heat Transfer Analysis for Asphalt Mixture Temperature Variation due to Wind Speed (풍속에 따른 포설 아스팔트 혼합물의 온도변화에 대한 열전달 해석)

  • Yun, Tae Young;Yoo, Pyeong Jun
    • International Journal of Highway Engineering
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    • v.17 no.4
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    • pp.33-40
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    • 2015
  • PURPOSES: Evaluation of the wind speed effect on the temperature drop of an asphalt mixture during construction, by using the transient heat transfer theory and dominant convective heat transfer coefficient model. METHODS: Finite difference method (FDM) is used to solve the transient heat transfer difference equation numerically for various wind speeds and initial temperature conditions. The Blasius convective heat transfer coefficient model is adapted to account for the effect of wind speed in the temperature predictions of the asphalt mixture, and the Beaufort number is used to select a reasonable wind speed for the analysis. As a function of time and depth, the temperature of the pavement structure is predicted and analyzed for the given initial conditions. RESULTS : The effect of wind speed on the temperature drop of asphalt mixture is found to be significant. It seems that wind speed is another parameter to be accounted for in the construction specifications for obtaining a better quality of the asphalt mixture. CONCLUSIONS: It is concluded that wind speed has a significant effect on the temperature drop of the asphalt layer. Although additional field observations have to be made to reflect the effect of wind speed on the construction specifications, it appears that wind speed is a dominant variable to be considered, in addition to the atmospheric temperature.

System identification of a super high-rise building via a stochastic subspace approach

  • Faravelli, Lucia;Ubertini, Filippo;Fuggini, Clemente
    • Smart Structures and Systems
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    • v.7 no.2
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    • pp.133-152
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    • 2011
  • System identification is a fundamental step towards the application of structural health monitoring and damage detection techniques. On this respect, the development of evolved identification strategies is a priority for obtaining reliable and repeatable baseline modal parameters of an undamaged structure to be adopted as references for future structural health assessments. The paper presents the identification of the modal parameters of the Guangzhou New Television Tower, China, using a data-driven stochastic subspace identification (SSI-data) approach complemented with an appropriate automatic mode selection strategy which proved to be successful in previous literature studies. This well-known approach is based on a clustering technique which is adopted to discriminate structural modes from spurious noise ones. The method is applied to the acceleration measurements made available within the task I of the ANCRiSST benchmark problem, which cover 24 hours of continuous monitoring of the structural response under ambient excitation. These records are then subdivided into a convenient number of data sets and the variability of modal parameter estimates with ambient temperature and mean wind velocity are pointed out. Both 10 minutes and 1 hour long records are considered for this purpose. A comparison with finite element model predictions is finally carried out, using the structural matrices provided within the benchmark, in order to check that all the structural modes contained in the considered frequency interval are effectively identified via SSI-data.

Ambient Vibration measurements and finite element modelling for the Hong Kong Ting Kau Bridge

  • Au, F.T.K.;Tham, L.G.;Lee, P.K.K.;Su, C.;Han, D.J.;Yan, Q.S.;Wong, K.Y.
    • Structural Engineering and Mechanics
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    • v.15 no.1
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    • pp.115-134
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    • 2003
  • The Ting Kau Bridge in Hong Kong is a cable-stayed bridge comprising two main spans and two side spans. The bridge deck is supported by three towers, an end pier and an abutment. Each of the three towers consists of a single reinforced concrete mast which reduces its section in steps, and it is strengthened by transverse cables and struts in the transverse vertical plane. The bridge deck is supported by four inclined planes of cables emanating from anchorages at the tower tops. In view of the threat from typhoons, the dynamic behaviour of long-span cable-supported bridges in the region is always an important consideration in their design. This paper is devoted to the ambient vibration measurements of the bridge for evaluation of dynamic characteristics including the natural frequencies and mode shapes. It also describes the modelling of the bridge. A few finite element models are developed and calibrated to match with the field data and the results of subsequent structural health monitoring of the bridge.

2.5 Dimensional EM Modeling considering Horizontal Magnetic Dipole Source (수평 자기쌍극자 송신원을 이용한 2.5차원 전자탐사 모델링)

  • Kwon Hyoung-Seok;Song Yoonho;Son Jeong-Sul;Suh Jung-Hee
    • Geophysics and Geophysical Exploration
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    • v.5 no.2
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    • pp.84-92
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    • 2002
  • In this study, the new modeling scheme has been developed for recently designed and tested electromagnetic survey, which adapts horizontal magnetic dipole with $1\;kHz\~1\;MHz$ frequency range as a source. The 2.5-D secondary field formulation in wavenumber domain was constructed using finite element method and verified through comparing results with layered-earth solutions calculated by integral equations. 2-D conductive- and resistive-block models were constructed for calculating electric field, magnetic field and impedance - the ratio of electric and magnetic fields which are orthogonal each other. This study showed that electric field and impedance are superior in identifying 2-D isolated-body model to magnetic field. In particular, impedance gives more stable results than electric field with similar spatial resolving power, because electric field is divided by magnetic field in impedance. Thus the impedance analysis which uses electric and magnetic fields together would give better result in imaging the shallow anomalies than conventional EM method.

Spark Plasma Sintering Method to Replace Carburizing Process (침탄 공정 대체를 위한 방전 플라즈마 소결 방법)

  • Jeon, Junhyub;Lee, Junho;Seo, Namhyuk;Son, Seung Bae;Jung, Jae-Gil;Lee, Seok-Jae
    • Journal of Powder Materials
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    • v.29 no.3
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    • pp.219-225
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    • 2022
  • An alternative fabrication method for carburizing steel using spark plasma sintering (SPS) is investigated. The sintered carburized sample, which exhibits surface modification effects such as carburizing, sintered Fe, and sintered Fe-0.8 wt.%C alloys, is fabricated using SPS. X-ray diffraction and micro Vickers tests are employed to confirm the phase and properties. Finite element analysis is performed to evaluate the change in hardness and analyze the carbon content and residual stress of the carburized sample. The change in the hardness of the carburized sample has the same tendency to predict hardness. The difference in hardness between the carburized sample and the predicted value is also discussed. The carburized sample exhibits a compressive residual stress at the surface. These results indicate that the carburized sample experiences a surface modification effect without carburization. Field emission scanning electron microscopy is employed to verify the change in phase. A novel fabrication method for altering the carburization is successfully proposed. We expect this fabrication method to solve the problems associated with carburization.

Hardware Design of Elliptic Curve processor Resistant against Simple Power Analysis Attack (단순 전력분석 공격에 대처하는 타원곡선 암호프로세서의 하드웨어 설계)

  • Choi, Byeong-Yoon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.1
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    • pp.143-152
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    • 2012
  • In this paper hardware implementation of GF($2^{191}$) elliptic curve cryptographic coprocessor which supports 7 operations such as scalar multiplication(kP), Menezes-Vanstone(MV) elliptic curve cipher/decipher algorithms, point addition(P+Q), point doubling(2P), finite-field multiplication/division is described. To meet structure resistant against simple power analysis, the ECC processor adopts the Montgomery scalar multiplication scheme which main loop operation consists of the key-independent operations. It has operational characteristics that arithmetic units, such GF_ALU, GF_MUL, and GF_DIV, which have 1, (m/8), and (m-1) fixed operation cycles in GF($2^m$), respectively, can be executed in parallel. The processor has about 68,000 gates and its simulated worst case delay time is about 7.8 ns under 0.35um CMOS technology. Because it has about 320 kbps cipher and 640 kbps rate and supports 7 finite-field operations, it can be efficiently applied to the various cryptographic and communication applications.

Characteristic Analysis of Double sided Slotless Halbach Array Permanent Magnet Linear Generator with Three Phases Concentrated Winding of Cored Type by using Analytical Method (해석적 방법을 이용한 3상 집중권 권선을 갖는 양측식 슬롯리스 고정자 Halbach 배열 영구자석 선형 발전기의 특성해석)

  • Seo, Sung-Won;Choi, Jang-Young;Hong, Keyyong;Kim, Kyong-Hwan
    • Journal of the Korean Magnetics Society
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    • v.25 no.2
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    • pp.58-65
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    • 2015
  • This paper deals with the generating characteristic analysis of permanent magnet linear generator (PMLG) with double-sided Halbach magnet array mover and three phases concentrated stator windings by using analytical method. On the basis of a magnetic vector potential and Maxwell's equations, governing equations are obtained, and magnetization modeling for Halbach magnet array is performed analytically by using the Fourier series. And then, we obtain electrical parameters such as back-EMF constant, resistance, and coil inductance based on magnetic field calculations. Finally, analytical results for generating performance are confirmed by comparing with finite element analysis results.

Efficient bit-parallel multiplier for GF(2$^m$) defined by irreducible all-one polynomials (기약인 all-one 다항식에 의해 정의된 GF(2$^m$)에서의 효율적인 비트-병렬 곱셈기)

  • Chang Ku-Young;Park Sun-Mi;Hong Do-Won
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.7 s.349
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    • pp.115-121
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    • 2006
  • The efficiency of the multiplier largely depends on the representation of finite filed elements such as normal basis, polynomial basis, dual basis, and redundant representation, and so on. In particular, the redundant representation is attractive since it can simply implement squaring and modular reduction. In this paper, we propose an efficient bit-parallel multiplier for GF(2m) defined by an irreducible all-one polynomial using a redundant representation. We modify the well-known multiplication method which was proposed by Karatsuba to improve the efficiency of the proposed bit-parallel multiplier. As a result, the proposed multiplier has a lower space complexity compared to the previously known multipliers using all-one polynomials. On the other hand, its time complexity is similar to the previously proposed ones.

Development of quasi-static analysis program for catenary mooring system using OpenFOAM (OpenFOAM을 이용한 catenary 계류시스템의 준정적 해석 프로그램 개발)

  • Choi, Jun Hyeok;Lee, Seung Jae
    • Journal of Ocean Engineering and Technology
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    • v.31 no.4
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    • pp.274-280
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    • 2017
  • Generally, global performance analysis in offshore platforms is performed using potential-based numerical tools, which neglect hydrodynamic viscous effects. In comparison with the potential theory, computational fluid dynamics (CFD) methods can take into account the viscous effects by solving the Navier-Stokes equation using the finite-volume method. The open-source field operation and manipulation (OpenFOAM) C++ libraries are employed for a finite volume method (FVM) numerical analysis. In this study, in order to apply CFD to the global performance analysis of a hull-mooring coupled system, we developed a numerical wave basin to analyze the global performance problem of a floating body with a catenary mooring system under regular wave conditions. The mooring system was modeled using a catenary equation and solved in a quasi-static condition, which excluded the dynamics of the mooring lines such as the inertia and drag effects. To demonstrate the capability of the numerical basin, the global performance of a barge with four mooring lines was simulated under regular wave conditions. The simulation results were compared to the analysis results from a commercial mooring analysis program, Orcaflex. The comparison included the motion of the barge, catenary shape, and tension in the mooring lines. The study found good agreement between the results from the developed CFD-based numerical calculation and commercial software.

Finite Element Analysis based on the Macroelement Method for the Design of Vacuum Consolidation (진공압밀공법 설계를 위한 Macro-element법 기반 유한요소해석)

  • Kim, Hayoung;Kim, Kyu-Sun
    • Journal of the Korean Geotechnical Society
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    • v.38 no.8
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    • pp.29-37
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    • 2022
  • A three-dimensional analysis is required to interpret the drainage behavior of an improved ground with vertical drains, and the macroelement method enables efficient interpretation considering the three-dimensional drainage effect of vertical drains under two-dimensional plane strain condition. In this study, a novel finite element analysis program was developed by applying the macroelement method to the vacuum consolidation method used in ground improvement practice. The conventional macroelement method was used to calculate the amount of drainage from the vertical drain by setting the excess porewater pressure in the drainage material to zero; however, the program developed in this study was improved to consider negative excess porewater pressure as an actual vacuum consolidation condition. To verify the performance of the program, because of a comparison with the measurement values at the site where the vacuum consolidation method was applied, results predicted by the program and field measurement data showed similar settlement behavior.