• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
• /
• pp.84-91
• /
• 1998

A numerically stable technique to remove tile limitation in choosing a shift in the subspace iteration method with shift is presented. A major difficulty of the subspace iteration method with shift is that because of singularity problem, a shift close to an eigenvalue can not be used, resulting in slower convergence. This study selves the above singularity problem using side conditions without sacrifice of convergence. The method is always nonsingular even if a shiht is an eigenvalue itself. This is one of tile significant characteristics of the proposed method. The nonsingularity is proved analytically. The convergence of the proposed method is at least equal to that of the subspace iteration method with shift, and the operation counts of above two methods are almost the same when a large number of eigenpairs are required. To show the effectiveness of the proposed method, two numerical examples are considered

• Journal of electromagnetic engineering and science
• /
• 제12권3호
• /
• pp.203-209
• /
• 2012

In order to improve sensing performance when the noise variance is not known, this paper considers a so-called blind spectrum sensing technique that is based on eigenvalue models. In this paper, we employed the spiked population models in order to identify the miss detection probability. At first, we try to estimate the unknown noise variance based on the blind measurements at a secondary location. We then investigate the performance of detection, in terms of both theoretical and empirical aspects, after applying this estimated noise variance result. In addition, we study the effects of the number of SUs and the number of samples on the spectrum sensing performance.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 A
• /
• pp.110-112
• /
• 2003

This paper presents an alleviant technique for solving ill-conditioned linear systems using spectral adaptive mapping, which is based on spectral mapping theorem. The conventional approaches to solve the ill-conditioned linear systems are divided into reformulation and alleviant technique. So far, the alleviant technique is evaluated the most effective one. In this paper, an adaptive mapping of spectrum is adopted to alleviate the condition number of ill-conditioned linear systems. A shift constant, which is a dominant factor of the spectral adaptive mapping that are proposed, is assessed by the system spectrum. The proposed spectral adaptive mapping technique is tested to demonstrated the validation on several size Hilbert matrices and small scale power systems, which are provide the promising results.

• 한국음향학회지
• /
• 제32권6호
• /
• pp.548-555
• /
• 2013

음원 위치 추정은 여러 방면에서 쓰임이 있는 응용 기술이다. 음원의 위치를 추정하기 위한 기본 기법 중에는 시간 지연 추정 기법이 있다. 이 기법에선 음원의 위치를 추정하기 위해서 두 개 또는 그 이상의 수신기에 들어오는 신호간의 상대적 시간 지연을 알아내야 한다. 시간 지연 추정 기법에는 GCC (Generalized Cross-Correlation) 대표적이지만, 최소 고유치에 대응하는 고유 벡터를 이용하는 방법도 많이 쓰인다. 이 방법은 최소 고유치에 해당하는 고유벡터를 이용한다. 최소 고유치에 대응하는 고유 벡터를 이용하는 방법은 낮은 신호 대 잡음비 환경에서나 상관도가 있는 잡음환경에서, 최소 고유치에 해당하는 고유 벡터를 추정하는데 어려움이 있어서, 성능이 떨어진다. 본 논문에서는 정준형 상관 분석 (CCA)를 이용한 새 기법을 제안한다. 이 방법은 일반 고유치 분해 중에서 최대 고유치에 대응하는 고유벡터를 사용한다. 따라서 추정에 사용하는 고유벡터는 시간 지연 추정에 필요한 정보가 충분히 들어있다. 본 논문에서는 여러 서로 다른 신호 대 잡음비 환경 하에서 상관도가 없는 경우와 상관도가 있는 경우의 잡음 에 대해 비교 모의실험을 하였고, 이 비교 실험을 통하여 얻는 데이터를 통해서 제안한 CCA 기반 알고리즘이 기존 최소 고유치에 해당하는 고유벡터를 사용하는 시간 지연 추정법의 성능보다 더 우수하다는 것을 보인다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
• /
• pp.133-140
• /
• 2002

This paper investigates the applicability of the modified Lanczos method using the power technique, which was developed in the field of quantum physics, to the eigenproblem in the field of engineering mechanics by introducing matrix-powered Lanczos recursion and numerically evaluating the suitable power value. The matrix-powered Lanczos method has better convergence and less operation count than the conventional Lanczos method. By analyzing four numerical examples, the effectiveness of the matrix-powered Lanczos method is verified and the appropriate matrix power is also recommended.

• Journal of applied mathematics & informatics
• /
• 제11권1_2호
• /
• pp.305-316
• /
• 2003

Recently, an iterative algorithm for finding the interior eigenvalues of a definite matrix by CG-type method has been proposed. This method compares to the inverse power method. The given matrices A, and B are assumed to be large and sparse, and SPD( Symmetric Positive Definite) The CG scheme for the optimization of the Rayleigh quotient has been proven a very attractive and promising technique for large sparse eigenproblems for smallest eigenvalue. Also, it is very amenable to parallel computations, like the CG method for the linear systems. A proper choice of the preconditioner significantly improves the convergence of the CG scheme. But for parallel computations we need to find an efficient parallel preconditioner. Our candidates we ILU(0) in the wave-front order, ILU(0) in the multi-coloring order, Point-SSOR(Symmetric Successive Overrelaxation), and Multi-Color Block SSOR preconditioner. Wavefront order is a simple way to increase parallelism in the natural order, and Multi-coloring realizes a parallelism of order(N), where N is the order of the matrix. Another choice is the Multi-Color Block SSOR(Symmetric Successive OverRelaxation) preconditioning. Block SSOR is a symmetric preconditioner which is expected to minimize the interprocessor communication due to the blocking. We implemented the results on the CRAY-T3E with 128 nodes. The MPI (Message Passing Interface) library was adopted for the interprocessor communications. The test problem was drawn from the discretizations of partial differential equations by finite difference methods. The results show that for small number of processors Multi-Color ILU(0) has the best performance, while for large number of processors Multi-Color Block SSOR performs the best.

• 전산구조공학
• /
• 제4권2호
• /
• pp.111-117
• /
• 1991

구조 공학에서의 고유치 문제는 좌굴해석, 진동해석 등 여러분야에 응용되고 있다. 일반적으로 구조물의 좌굴강도 해석에 사용되는 대부분의 변수들은 불확실성을 내포하고 있으므로 확률론적 해석을 수행해야 하지만, 구조물의 좌굴 신뢰성 해석을 위한 극한상태 방정식은 확률변수의 함수로 명확히 표현되지 않으므로 확률 유한 요소법의 사용이 필요하다. 따라서 본 논문에서는 직접미분법에 의해 정식화된 확률 유한요소법을 사용하여 고유치 문제의 신뢰성 해석방법을 정식화 하고, 이를 바탕으로 좌굴 신뢰성 해석을 수행하였으며, 결과의 타당성을 검증하기 위하여 Crude Monte Carlo Method 및 이 방법의 단점을 대폭 보완한 Importance Sampling Method를 사용하였다. 본 논문에 의해 좌굴 신뢰성 해석 방법이 정립됨으로서 신뢰성에 기초한 최적 설계를 수행하는 경우, 시스템 파괴확률로서 소성 파괴확률과 더불어 좌굴 파괴확률의 고려가 가능해졌다.

• Journal of Information Processing Systems
• /
• 제16권5호
• /
• pp.1064-1073
• /
• 2020

The general situation of system composition and safety management of high-speed railway terminal is investigated and a comprehensive evaluation index system of operational security is established on the basis of railway laws and regulations and previous research results to evaluate the operational security management of the high-speed railway terminal objectively and scientifically. Index weight is determined by introducing interval eigenvalue method (IEM), which aims to reduce the dependence of judgment matrix on consistency test and improve judgment accuracy. Operational security status of a high-speed railway terminal in northwest China is analyzed using the traditional model of fuzzy comprehensive evaluation, and a general technique idea and references for the operational security evaluation of the high-speed railway terminal are provided. IEM is introduced to determine the weight of each index, overcomes shortcomings of traditional analytic hierarchy process (AHP) method, and improves the accuracy and scientificity of the comprehensive evaluation. Risk factors, such as terrorist attacks, bad weather, and building fires, are intentionally avoided in the selection of evaluation indicators due to the complexity of risk factors in the operation of high-speed railway passenger stations and limitation of the length of the paper. However, such risk factors should be considered in the follow-up studies.

• Computers and Concrete
• /
• 제25권4호
• /
• pp.303-310
• /
• 2020

In this research, a hybrid mathematical model is derived using the higher-order polynomial kinematic model in association with soft computing technique for the prediction of best fiber volume fractions and the minimal mass of the layered composite structure. The optimal values are predicted further by taking the frequency parameter as the constraint and the projected values utilized for the computation of the eigenvalue and deflections. The optimal mass of the total layered composite and the corresponding optimal volume fractions are evaluated using the particle swarm optimization by constraining the arbitrary frequency value as mass/volume minimization functions. The degree of accuracy of the optimal model has been proven through the comparison study with published well-known research data. Further, the predicted values of volume fractions are incurred for the evaluation of the eigenvalue and the deflection data of the composite structure. To obtain the structural responses i.e. vibrational frequency and the central deflections the proposed higher-order polynomial FE model adopted. Finally, a series of numerical experimentations are carried out using the optimal fibre volume fraction for the prediction of the optimal frequencies and deflections including associated structural parameter.

• 한국소음진동공학회논문집
• /
• 제16권4호
• /
• pp.394-403
• /
• 2006

A new equivalent linearization technique is proposed for a friction damper-brace system (FDBS) idealized as a elastoplastic system. The equivalent linearization technique utilizes secant stiffness and dissipated energy defined by the probability distribution of the extremal displacement of the FDBS. In addition, a conversion scheme is proposed so that an equivalent linear system is designed first and converted to the FDBS. For comparative study, an existing model update technique based on system identification is modified in a form appropriate to update single element. For the purpose of verification, shaking table tests of a small scale three-story shear building model, in which a rotational FDBS is installed, are conducted and equivalent linear systems are obtained using the proposed technique and the model update technique. Complex eigenvalue analysis is conducted for those equivalent linear systems, and the natural frequencies and modal damping ratios are compared with those obtained from system identification. Additionally, RMS and peak responses obtained from time history analysis of the equivalent linear systems are compared with measured ones.