• Nuclear Engineering and Technology
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• v.13 no.2
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• pp.73-84
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• 1981

B$\Phi$rrensen proposed a coarse mesh, three-dimensional one-and-half group diffusion scheme for computing the gross power distribution in light water reactors as an alternative to the conventional fine mesh finite difference approach in dealing with three dimensional problems, which require a prohibitively long computing time. The method reported takes extremely small execution time. However, its computational accuracy has not been investigated yet. The B$\Phi$rrensen method is revised in this work and both efficiency and accuracy are examined by applying it to IAEA benchmark problem and RIS$\Phi$ benchmark problem. It is found that two modifications on core-reflector boundary conditions and B$\Phi$rrensen's model constants may improve computational accuracy of power distribution calculation.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2422-2430
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• 2020

In order to improve calculational efficiency of the CAPP code in the analysis of the hexagonal reactor core, we have tried to implement a refined AFEN method with transverse gradient basis functions and interface flux moments in the hexagonal geometry. The numerical scheme for the refined AFEN method adopted here is the response matrix method that uses the interface partial currents as nodal unknowns instead of the interface fluxes used in the original AFEN method. Since the response matrix method is single-node based, it has good properties such as good calculational efficiency and parallel computing affinity. Because a refined AFEN method equivalent nonlinear FDM response matrix method tried first could not provide a numerically stable solution, a direct formulation of the refined AFEN response matrix were developed. To show the numerical performance of this response matrix method against the original AFEN method, the numerical error analyses were performed for several benchmark problems including the VVER-440 LWR benchmark problem and the MHTGR-350 HTGR benchmark problem. The results showed a more than three times speedup in computing time for the LWR and HTGR benchmark problems due to good convergence and excellent calculational efficiency of the refined AFEN response matrix method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.85-91
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• 2023

In order to utilize KOSMOS, the performance evaluation results are presented in this paper with CloudSuite, an application service-based benchmark program in the cloud computing area. CloudSuite offers several distinct applications as cloud services in two parts: offline applications and online applications on containers. In comparison with other microservers which have similar hardware specifications of KOSMOS, it was observed that KOSMOS was superior in all CloudSuite benchmark applications. KOSMOS also showed higher performance than Intel Xeon CPU-based servers in an offline application. KOSMOS reduced completion time during executing Graph Analytics by 30.3% and 72.3% compared to two Intel Xeon CPU-based servers in an experimental configuration of multiple nodes in KOSMOS.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1521-1530
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• 2002

This article proposes a pressure based method for predicting flows at all speeds. The compressible SIMPLE algorithm is extended to unstructured grid framework. Convection terms are discretized using second-order scheme with deferred correction approach. Diffusion term discretization is based on structured grid analogy that can be easily adopted to hybrid unstructured grid solver. This method also uses node centered scheme with edge based data structure for memory and computing time efficiency of arbitrary grid types. Both incompressible and compressible benchmark problems are solved using the above methodology. The demonstration of this method is extended to slip flow problem that has low Reynolds number but compressibility effect. It is shown that the proposed method can improve efficiency in memory usage and computing time without losing any accuracy.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.87-92
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• 1998

A nonlinear iterative scheme developed to reduce the computing time of the AFEN method was tested and applied to two benchmark problems. The new nonlinear method for the AFEN method is based on solving two-node problems and use of two nonlinear correction factors at every interface instead of one factor in the conventional scheme. The use of two correction factors provides higher-order accurate interface noes as well as currents which are used as the boundary conditions of the two-node problem. The numerical results show that this new method gives exactly the same solution as that of the original AEFEN method and the computing time is significantly reduced in comparison with the original AFEN method.

• International Journal of Computer Science & Network Security
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• v.21 no.4
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• pp.131-139
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• 2021

In current time, anomaly detection is the primary concern of the administrative authorities. Suspicious activity identification is shifting from a human operator to a machine-assisted monitoring in order to assist the human operator and react to an unexpected incident quickly. These automatic surveillance systems face many challenges due to the intrinsic complex characteristics of video sequences and foreground human motion patterns. In this paper, we propose a novel approach to detect anomalous human activity using a hybrid approach of statistical model and Genetic Programming. The feature-set of local motion patterns is generated by a statistical model from the video data in an unsupervised way. This features set is inserted to an enhanced Genetic Programming based classifier to classify normal and abnormal patterns. The experiments are performed using publicly available benchmark datasets under different real-life scenarios. Results show that the proposed methodology is capable to detect and locate the anomalous activity in the real time. The accuracy of the proposed scheme exceeds those of the existing state of the art in term of anomalous activity detection.

• Nuclear Engineering and Technology
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• v.28 no.3
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• pp.311-319
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• 1996

We reconstruct the assembly pinwise flux using several types of boundary conditions and confirm that the reconstructed fluxes are the same with the reference flux if the boundary condition is exact. We test EPRI-9R benchmark problem with four boundary conditions, such as Dirichlet boundary condition, Neumann boundary condition, homogeneous mixed boundary condition (albedo type), and inhomogeneous mixed boundary condition. We also test reconstruction of the pinwise flux from nodal values, specifically from the AFEN [1, 2] results. From the nodal flux distribution we obtain surface flux and surface current distributions, which can be used to construct various types of boundary conditions. The result show that the Neumann boundary condition cannot be used for iterative schemes because of its ill-conditioning problem and that the other three boundary conditions give similar accuracy. The Dirichlet boundary condition requires the shortest computing time. The inhomogeneous mixed boundary condition requires only slightly longer computing time than the Dirichlet boundary condition, so that it could also be an alternative. In contrast to the fixed-source type problem resulting from the Dirichlet, Neumann, inhomogeneous mixed boundary conditions, the homogeneous mixed boundary condition constitutes an eigenvalue problem and requires longest computing time among the three (Dirichlet, inhomogeneous mixed, homogeneous mixed) boundary condition problems.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.45-48
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• 2003

We can easily buy network system for high performance micro-processor, progress computer architecture is caused of high bandwidth and low delay time. Coupling PC-based commodity technology with distributed computing methodologies provides an important advance in the development of single-user dedicated systems. Lately Network is joined PC or workstation by computers of high performance and low cost. Than it make intensive that Cluster system is resembled supercomputer. Unix, Linux, BSD, NT(Windows series) can use Cluster system OS(operating system). I'm chosen linux gain low cost, high performance and open technical documentation. This paper is benchmark performance of Beowulf clustering by UltraSPARC-1K(64bit-RISC processor). Benchmark tools use MPI(Message Passing Interface) and NetPIPE. Beowulf is a class of experimental parallel workstations developed to evaluate and characterize the design space of this new operating point in price-performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.396-413
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• 2017

Dynamically checking the integrity of software at run-time is always a hot and difficult spot for trusted computing. Control-flow integrity is a basic and important safety property of software integrity. Many classic and emerging security attacks who introduce illegal control-flow to applications can cause unpredictable behaviors of computer-based systems. In this paper, we present a software-based approach to checking violation of control flow integrity at run-time. This paper proposes a high-performance and low-overhead software control flow checking solution, control flow checking at virtual edges (CFCVE). CFCVE assigns a unique signature to each basic block and then inserts a virtual vertex into each edge at compile time. This together with insertion of signature updating instructions and checking instructions into corresponding vertexes and virtual vertexes. Control flow faults can be detected by comparing the run-time signature with the saved one at compile time. Our experimental results show that CFCVE incurs only 10.61% performance overhead on average for several C benchmark programs and the average undetected error rate is only 9.29%. Compared with previous techniques, CFCVE has the characteristics of both high fault coverage and low memory and performance overhead.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.2
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• pp.183-194
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• 2002

The clustering environment with heterogeneous workstations provides the cost effectiveness and usability for executing applications in parallel. Load balancing is considered a necessary feature for a cluster of heterogeneous workstations to minimize the turnaround time. Previously, static load balancing that assigns a predetermined weight for the processing capability of each workstation, or dynamic approaches which execute a benchmark program to get relative processing capability of each workstation were proposed. The execution of the benchmark program, which has nothing to do with the application being executed, consumes the computation time and the overall turnaround time is delayed. In this paper, we present efficient methods for task distribution and task migration, based on the relative load index. We designed and implemented a load balancing system for the clustering environment with heterogeneous workstations. Turnaround times of our methods and the round-robin approach, as well as the load balancing method using a benchmark program, were compared. The experimental results show that our methods outperform all the other methods that we compared.