• Title, Summary, Keyword: analysis and computation

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Efficiency of a Symbolic Computation Method for the Real Time Simulation (실시간 시뮬레이션을 위한 기호연산기법의 유용성 검증에 관한 연구)

  • Choe, Dae-Han;Yu, Wan-Seok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.7
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    • pp.1878-1884
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    • 2000
  • In multibody dynamic analysis, one of the most important problems is to reduce computation times for real time simulation. In this paper, a symbolic computation method is implemented and tested for each dynamic analysis step. Applying symbolic formulations to the vehicle dynamics program AutoDyn7, the effectiveness of the symbolic computation method is verified.

DEVELOPMENT OF A CORE THERMO-FLUID ANALYSIS CODE FOR PRISMATIC GAS COOLED REACTORS

  • Tak, Nam-Il;Lee, Sung Nam;Kim, Min-Hwan;Lim, Hong Sik;Noh, Jae Man
    • Nuclear Engineering and Technology
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    • v.46 no.5
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    • pp.641-654
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    • 2014
  • A new computer code, named CORONA (Core Reliable Optimization and thermo-fluid Network Analysis), was developed for the core thermo-fluid analysis of a prismatic gas cooled reactor. The CORONA code is targeted for whole-core thermo-fluid analysis of a prismatic gas cooled reactor, with fast computation and reasonable accuracy. In order to achieve this target, the development of CORONA focused on (1) an efficient numerical method, (2) efficient grid generation, and (3) parallel computation. The key idea for the efficient numerical method of CORONA is to solve a three-dimensional solid heat conduction equation combined with one-dimensional fluid flow network equations. The typical difficulties in generating computational grids for a whole core analysis were overcome by using a basic unit cell concept. A fast calculation was finally achieved by a block-wise parallel computation method. The objective of the present paper is to summarize the motivation and strategy, numerical approaches, verification and validation, parallel computation, and perspective of the CORONA code.

A Study on the Time Required and Error Tolerance Limits for Flight Data Computation (비행자료산출을 위한 소요시간과 정답오차범위에 관한 연구)

  • Kim, Chil-Young;Han, Kyoung-Keun
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.6 no.1
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    • pp.21-29
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    • 1998
  • The purpose of the present paper is to determine the time required and error tolerance limits for flight data computation. The results of statistical analysis showed that the calculator side computation required about 50 seconds for each question and wind side computation needed about 115 seconds for each question. In case of error tolerance limits, it was found that the error tolerance limit for altitude computation war 90 feet and two knots of interval was recommanded for the speed computation in calculator side, and one degree of interval for heading computation and five knots interval for speed computation in wind side.

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Transient Response Analysis of Frame Structures Using the Finite Element-transfer Stiffness Coefficient Method (FE-TSCM) (유한요소-전달강성계수법을 이용한 골조 구조물의 과도응답해석)

  • 최명수;문덕홍;김성진
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.9
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    • pp.674-684
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    • 2002
  • In order to decrease remarkably the computation time and storage used in the direct integration method without the loss of accuracy, authors suggest a new transient analysis algorithm. This algorithm is derived from the combination of three techniques, that is, the transfer technique of the transfer stiffness coefficient method, the modeling technique of the finite element method, and the numerical integration technique of the Newmark method. In this paper, the transient analysis algorithm of a frame structure is formulated by the proposed method. The accuracy and computation efficiency of the proposed method are demonstrated through the comparing with the computation results by the direct integration method for three computation models under various excitations.

Analysis of Three-dimensional Nonaxisymmetric Spin-up by Using Parallel Computation (병렬계산에 의한 비축대칭 3차원 스핀업 유동해석)

  • Park, Jae-Hyoun;Choi, Yoon-Hwan;Suh, Yong-Kweon
    • Proceedings of the KSME Conference
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    • pp.512-517
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    • 2001
  • In this study, spin-up flows in a rectangular container are analysed by using three-dimensional computation. In the numerical computation, we use the parallel computer system of PC-cluster type. We compared our results with those obtained by two-dimensional computation. Effect of velocity and vorticity on the flow is studied. The result shows that two-dimensional solution is in good agreement with the 3-D result. Attention is given to the region where the 3-D flow is significant.

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A Fast Computation Method of Power Ground Plane Impedance using the Mobius Transform (Mobius변환을 이용한 전력접지층 임피던스의 빠른 계산방법)

  • Suh Youngsuk;Kim In-Sung;Song Jae-Sung;Eum Tae-Su
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.1
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    • pp.41-44
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    • 2005
  • A new method to reduce the computation time in power/ground-plane analysis is proposed. The existing method using the two dimensional infinite series summation take a lot of computation time. The proposed method is based on the approximation of impedance in the frequency domain through the Mobius transform. This method shows the good accuracy and the high speed in computing. In the case of impedance calculation for 9'x4' board, the proposed method takes 0.16 second of computing time whereas the existing method takes 2.2 second. This method can be applied to the analysis and design of power/ground-plane that need a lot of computation steps.

Boltzmann machine using Stochastic Computation (확률 연산을 이용한 볼츠만 머신)

  • 이일완;채수익
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.6
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    • pp.159-168
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    • 1994
  • Stochastic computation is adopted to reduce the silicon area of the multipliers in implementing neural network in VLSI. In addition to this advantage, the stochastic computation has inherent random errors which is required for implementing Boltzmann machine. This random noise is useful for the simulated annealing which is employed to achieve the global minimum for the Boltzmann Machine. In this paper, we propose a method to implement the Boltzmann machine with stochastic computation and discuss the addition problem in stochastic computation and its simulated annealing in detail. According to this analysis Boltzmann machine using stochastic computation is suitable for the pattern recognition/completion problems. We have verified these results through the simulations for XOR, full adder and digit recognition problems, which are typical of the pattern recognition/completion problems.

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A Study on the Real-Time Analysis of a 6×6 Autonomous Vehicle (6×6 자율주행 차량의 실시간 해석을 위한 연구)

  • Cho, Du-Ho;Lee, Jung-Han;Yi, Ki-Chang;Yoo, Wan-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.12
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    • pp.1433-1441
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    • 2009
  • In multibody dynamic analysis, one of the most important problems is to reduce computation times for real-time simulation. This paper presents the derivation procedure of equations of motion of a 6${\times}$6 autonomous vehicle in terms of chassis local coordinates which do not require coordinates transformation matrix to enhance efficiency for real-time dynamic analysis. Also, equations of motion are derived using the VT(velocity transformation) technique and symbolic computation method coded by MATLAB. The Jacobian matrix of the equations of motion of a system is derived from symbolic operations to apply the implicit integration method. The analysis results were compared with ADAMS results to verify the accuracy and approve the feasibility of real time analysis.

Symbolic computation and differential quadrature method - A boon to engineering analysis

  • Rajasekaran, S.
    • Structural Engineering and Mechanics
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    • v.27 no.6
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    • pp.713-739
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    • 2007
  • Nowadays computers can perform symbolic computations in addition to mere number crunching operations for which they were originally designed. Symbolic computation opens up exciting possibilities in Structural Mechanics and engineering. Classical areas have been increasingly neglected due to the advent of computers as well as general purpose finite element software. But now, classical analysis has reemerged as an attractive computer option due to the capabilities of symbolic computation. The repetitive cycles of simultaneous - equation sets required by the finite element technique can be eliminated by solving a single set in symbolic form, thus generating a truly closed-form solution. This consequently saves in data preparation, storage and execution time. The power of Symbolic computation is demonstrated by six examples by applying symbolic computation 1) to solve coupled shear wall 2) to generate beam element matrices 3) to find the natural frequency of a shear frame using transfer matrix method 4) to find the stresses of a plate subjected to in-plane loading using Levy's approach 5) to draw the influence surface for deflection of an isotropic plate simply supported on all sides 6) to get dynamic equilibrium equations from Lagrange equation. This paper also presents yet another computationally efficient and accurate numerical method which is based on the concept of derivative of a function expressed as a weighted linear sum of the function values at all the mesh points. Again this method is applied to solve the problems of 1) coupled shear wall 2) lateral buckling of thin-walled beams due to moment gradient 3) buckling of a column and 4) static and buckling analysis of circular plates of uniform or non-uniform thickness. The numerical results obtained are compared with those available in existing literature in order to verify their accuracy.

Computation and Communication Efficient Key Distribution Protocol for Secure Multicast Communication

  • Vijayakumar, P.;Bose, S.;Kannan, A.;Jegatha Deborah, L.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.4
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    • pp.878-894
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    • 2013
  • Secure multimedia multicast applications involve group communications where group membership requires secured dynamic key generation and updating operations. Such operations usually consume high computation time and therefore designing a key distribution protocol with reduced computation time is necessary for multicast applications. In this paper, we propose a new key distribution protocol that focuses on two aspects. The first one aims at the reduction of computation complexity by performing lesser numbers of multiplication operations using a ternary-tree approach during key updating. Moreover, it aims to optimize the number of multiplication operations by using the existing Karatsuba divide and conquer approach for fast multiplication. The second aspect aims at reducing the amount of information communicated to the group members during the update operations in the key content. The proposed algorithm has been evaluated based on computation and communication complexity and a comparative performance analysis of various key distribution protocols is provided. Moreover, it has been observed that the proposed algorithm reduces the computation and communication time significantly.