• Computational Structural Engineering
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• v.5 no.2
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• pp.37-42
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• 1992

크레이 리서치(Cray Research Inc.)는 1972년 미국의 Seymour Cary가 슈퍼컴퓨터의 설계, 제작, 판매 및 기술지원을 목표로 Wisconsin주 Chippew Fall에 설립한 회사로, 혀재까지 세계 각지에서 300여 시스템을 공급한 슈퍼컴퓨터의 선두주자이다. 슈퍼컴퓨터의 역사를 이야기 할 때 크레이의 역사를 빼놓을 수 없을 정도로, 크레이 리서치는 1976년 세계최초의 슈퍼컴퓨터인 CRAY-1 시스템을 발표한 이래 끊임없는 연구노력을 경주하여, 1982년에 CRAY X-MP 시스템, 1985년에 CARY-2 시스템, 1988년에 CRAY Y-MP 시스템, 1992년에 CRAY C-90 시스템을 발표하였으며, 이들 시스템들은 각각 당 시대에 세계 최고의 성능을 지닌 슈퍼컴퓨터로 공인되어져 왔다.

• Computational Structural Engineering
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• v.5 no.2
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• pp.18-27
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• 1992

88년 9월중에 한국과학기술연구원 시스템공학연구소가 당시의 슈퍼컴퓨터 중 최상위 성능을 가진 Cray-2S(4 CPU, 1GB)를 설치함에 따라 국내에도 슈퍼컴퓨터 시대가 열리게 되었으며, 90년 10월에 산업계에서는 최초로 기아자동차에서 Cray Y/MP(1CPU)를 설치한 이래 최근에 국방과학연구소, 삼성그룹에서도 Cray Y/MP계열의 슈퍼컴퓨터를 설치하여 과학기술 계산 및 공학해석에 폭넓게 활용할 전망이다. 따라서 본 고에서는 슈퍼컴퓨터의 정의 및 분류, 특징과 보급현황에 대하여 알아보고 슈퍼컴퓨터 및 병렬처리기술을 이용한 유한요소해석에 관하여 간략히 기술하고저 한다.

• Structural Engineering and Mechanics
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• v.2 no.2
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• pp.125-139
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• 1994

A vector algorithm for calculating the stiffness matrices of reinforced concrete shell elements is presented. The algorithm is based on establishing vector lengths equal to the number of elements. The computational efficiency of the proposed algorithm is assessed on a Cray Y-MP supercomputer. It is shown that the vector algorithm achieves scalar-to-vector speedup of 1.7 to 7.6 on three moderate sized inelastic problems.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.4
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• pp.26-30
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• 2003

The Lanczos algorithm is the most commonly used in approximating a small number of extreme eigenvalues for symmetric large sparse matrices. Global communications in MP(Message Passing) parallel computer decrease the computation speed. In this paper, we introduce the s-step Lanczos method, and s-step method generates reduction matrices which are similar to reduction matrices generated by the standard Lanczos method. One iteration of the s-step Lanczos algorithm corresponds to s iterations of the standard Lanczos algorithm. The s-step method has the minimized global communication and has the superior parallel properties to the standard method. These algorithms are implemented on Cray T3E and performance results are presented.

• Structural Engineering and Mechanics
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• v.3 no.2
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• pp.173-183
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• 1995

A new vector algorithm is presented for computing the stiffness matrices of layered reinforced concrete shell elements. Each element stiffness matrix is represented in terms of three vector arrays of lengths 78, 96 and 36, respectively. One element stiffness matrix is calculated at a time without interruption in the vector calculations for the uncracked or cracked elements. It is shown that the present algorithm is 1.1 to 7.3 times more efficient then a previous algorithm developed by us on a Cray Y-MP supercomputer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.132-141
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• 1998

A parallel version of sheet forming analysis program was developed. This version is compatible with any parallel computers which support MPI that is one of the most recent and popular message passing libraries. For this purpose, SERI-SFA, a vector version which runs on Cray Y-MP C90, a sequential vector computer, was used as a source code. For the sake of the effectiveness of the work, the parallelization was focused on the selected part after checking the rank of CPU consumed from the exemplary calculation on Cray Y-MP C90. The subroutines associated with contact algorithm was selected as targe parts. For this work, MPI was used as a message passing library. For the performance verification, an oil pan and an S-rail forming simulation were carried out. The performance check was carried out by the kernel and total CPU time along with theoretical performance using Amdahl's Law. The results showed some performance improvement within the limit of the selective paralellization.

• Computers and Concrete
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• v.2 no.5
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• pp.345-366
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• 2005

This work presents an assessment of the computational performance of a vector-parallel implementation of probabilistic model for concrete cracking in 3D. This paper shows the continuing efforts towards code optimization as reported in earlier works Paz, et al. (2002a,b and 2003). The probabilistic crack approach is based on the direct Monte Carlo method. Cracking is accounted by means of 3D interface elements. This approach considers that all nonlinearities are restricted to interface elements modeling cracks. The heterogeneity governs the overall cracking behavior and related size effects on concrete fracture. Computational kernels in the implementation are the inexact Newton iterative driver to solve the non-linear problem and a preconditioned conjugate gradient (PCG) driver to solve linearized equations, using an element by element (EBE) strategy to compute matrix-vector products. In particular the paper analyzes code behavior using OpenMP directives in parallel vector processors (PVP), such as the CRAY SV1 and CRAY T94. The impact of the memory architecture on code performance, and also some strategies devised to circumvent this issue are addressed by numerical experiment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.25-30
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• 1994

A vector algorithm for calculating the stiffness matrices of reinforced concrete shell elements is presented. The algorithm is based on establishing vector lengths equal to the number of elements. The computational efficiency of the proposed algorithm is assessed on a Cray Y-MP supercomputer. It is shown that the vector algorithm achieves scalar-to-vector speedup of 1.7 to 7.6 on three inelastic problems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.59-70
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• 1992

Inelastic nonlinear behavior of a hyperbolic cooling tower under wind loading is studied using a finite element program developed on a Cray Y-MP. Convergence studies for the elastic and inelastic analyses are performed using three mesh models. It is shown that the mesh convergence plays an important role in accurately predicting the inelastic behavior of a cooling tower. Even though the cooling tower resists the applied forces through membrane stresses, it is found that the bending stresses play an important role in the failure and behavior of the cooling tower. The present analysis gives a shape factor of 1.48, which indicates a significant redistribution of meridional stresses. It is further evidenced by the distribution of meridional reinforcement yielding which reaches up to $30^{\circ}$ from the windward meridian. The present practice of using elastic analysis for calculating the design stresses appears to be at least safe and conservative. A more comprehensive study should lead to conclusions that would allow use of a higher-than-one shape factor, thus requiring less meridional reinforcement than the present design method does.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.11-20
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• 1993

Nonlinear inelastic behavior of an HP saddle shell has been examined by a finite element computer program developed on a Cray Y-MP. The mesh convergence is studied using three progressively refined finite element mesh models, $16{\times}16$, $32{\times}32$ and $64{\times}64$, for the elastic and inelastic analyses. It is shown that the $32{\times}32$ mesh model gives a solution that is very close to that given by the $64{\times}64$ mesh model, thus, showing a convergence. The inelastic analysis shows that the shell has a tremendous capacity to redistribute the stresses. At the ultimate, the concrete cracks and the reinforcement yieldings are spread out all over the shell, indicating that the stress distribution in the shell is approaching that given by the classical membrane theory. The present computer program provides a very useful tool for evaluating the nonlinear ultimate behavior of concrete shells during the design process.