• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.133-140
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• 2018

In this paper, we develop an automated software for in-plane structural analysis of composite laminated structures. The developed software supports various failure criteria and reports the analysis results considering user's convenience. It also provides batch job analysis function based on parallel processing technique. To verify the performance of the software, we compared margin of safety(MS) calculated in the software to those obtained from in-house method and the specimen experiment. As a result of comparisons, there was an error of less than 0.01 in the in-house method and it is within about ${\pm}10%$ with the specimen experiment. In addition, we confirmed the improvement of execution speed of batch job analysis based on parallel processing technique.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.335-336
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• 2007

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1297-1301
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• 1997

Generally, singularity analysis of 6-DOF parallerl manipulators is very difficult and, as result, velocity relation has many uncertainties. In this paper, an alternative method using the local structurizatioin method(LSM) for the analysis of singular configuraions is presented. With LSM, the velocity relation can be represented in a simple form, and the result is totally equivalent to the conventional velocity relation. The velocity relation suggested in this paper gives a closed-form solution of singularities.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1105-1108
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• 2005

Media service model is divided into 3 models that are Client Pull, Server Push, and IPP(Interleaving Pull & Push) model. In most single VOD(Video On Demand) environment, Client Pull model was sufficient to play the movie Because most media contents has a low bitrate and resolution. But according to an increment of the demand of the high definition media, Client Pull model is not sufficient. Parallel VOD environment is made of several of VOD servers and provides the parallel media stream simultaneously for one client. We compared and analyzed the performance of service models with respect to network delay and data size in buffer in the single and parallel VOD environment and we found that IPP service model keeps the least network delay and stable client buffer state in the parallel VOD environment.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.7
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• pp.379-386
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• 2004

We designed a portable parallel library HPCL(High Performance Computing Library) with following objectives: (1) to provide a close relationship between the parallel code and the original sequential code that will help future versions of the sequential code and (2) to enhance performance of the parallel code. The library is an interface written in C and Fortran programming languages between MPI(Message Passing Interface) and parallel programs in Fortran. Performance results were determined on clusters of PC's and IBM SP4.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.149-154
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• 2001

Parallel performance of a Myrinet based PC-cluster was tested and compared with a conventional Fast-Ethernet system. A preconditioned Navier-Stokes code was parallelized with domain decomposition technique, and used for the parallel performance test. Speed-up ratio was examined as a major performance parameter depending on the number of processor and the network topology. As was expected, Myrinet system shows a superior parallel performance to the Fast-Ethernet system even with a single network adpater for a dual processor SMP machine. A test for the dependency on problem size also shows that network communication speed is a crucial factor for parallelized computational fluid dynamics analysis and the Myrinet system is a plausible candidate for high performance parallel computing system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1688-1695
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• 2008

Recently, it is common in a distribution system of Korea Electric Power Corporation (KEPCO) to find instances where distribution lines are parallel. A traditional method of an induced voltage calculation is not suitable for parallel distribution lines. For more actual analysis of induced voltage on telecommunication lines in parallel distribution lines, a new calculation method is needed. This paper presents a new calculation method of an induced voltage on telecommunication line using equivalent ${\pi}$ circuits matrix in parallel distribution lines. The advantages of the calculation method are using actual neutral current value and not using screening factor for considering the overhead ground wire and the neutral wire. To verify the effectiveness and the accuracy of the method, various case studies are performed with EMTP(Electro-Magnetic Transients Program).

• Tribology and Lubricants
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• v.16 no.2
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• pp.106-113
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• 2000

Effects of surface roughness on bearing performances are investigated numerically in this study, especially for the parallel thrust bearing. Although mating surfaces are parallel and separated by thin fluid film, the pressure distribution is formed due to asperities. Model surface is generated numerically with given autocorrelation function and some surface profile parameters. Then the average Reynolds equation is applied to predict the effects of surface roughness between hydrodynamic and mixed lubrication regimes. In this equation, flow factors are defined as correction terms to smooth out high frequency surface roughness. The correlation length is proposed to get the minimum load for the parallel thrust bearing for various sliding conditions.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.2
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• pp.138-144
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• 2006

Kinematic and dynamic characteristics of a Stewart platform based parallel manipulators are fixed once they are constructed. Thus parallel manipulators with various configurations are required to meet a variety of applications. In this research a parallel manipulator with variable platform (PMVP) has been developed, in which the length of the arm linking the platform center to the platform-leg contact point can be varied by an actuator. The workspace of the PMVP is larger than that of a traditional Stewart platform and especially the range in which the maximum orientation angles can be maintained is significantly expanded. Furthermore, the characteristics of force and moment transmission between the legs and platform can be adjusted to meet the requirements of various tasks. Kinematic and dynamics analysis was performed to verify the usefulness of the PMVP and the actual hardware was built to demonstrate the feasibility.

• The Transactions of the Korea Information Processing Society
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• v.2 no.2
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• pp.148-155
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• 1995

When we analize many amount of patterns, it is necessary for these patterns are to be clustering into several groups according to a certain evaluation function. This process, in case that there are lots of input patterns, needs a considerable amount of computations and is reqired parallel algorithm for these. To solve this problem, this paper propose parallel clustering algorithm which parallelized k-means algorithm and implemented it under the MIMD parallel computer based message passing. The result is through the experiment and performance analysis, that this parallel algorithm is appropriate in case these are many input patterns.