• Journal of the Korean Society for Heat Treatment
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• v.14 no.6
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• pp.336-344
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• 2001

For the establishment of the world wide unified scales of the Rockwell hardness test with conical indenters, round robin test was carried from 1998 to 2000. The pilot laboratory was MPA-NRW and 12 laboratories from 11 countries participated In this RRT. Rockwell hardness of 74 specially prepared blocks was measured for the scales of C, A, D, 45N, 30N, and 15N and the results were compared. It was found that the geometric form of indenter affects on the results very significantly and standardization in the measurement and evaluation of indenter should be established in short time for the reliable hardness measurement. KRISS showed good results in general for all of the ranges except 15N scale which showed relatively large difference compare to the mean value. It was concluded that poor control in loading velocity of the dash pot was the major reason.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1412-1422
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• 2016

Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

• International Journal of Computer Science & Network Security
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• v.21 no.2
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• pp.158-170
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• 2021

Virtualization technologies are being adopted and broadly utilized in many fields and at different levels. In cloud computing, achieving load balancing across large distributed virtual machines is considered a complex optimization problem with an essential importance in cloud computing systems and data centers as the overloading or underloading of tasks on VMs may cause multiple issues in the cloud system like longer execution time, machine failure, high power consumption, etc. Therefore, load balancing mechanism is an important aspect in cloud computing that assist in overcoming different performance issues. In this research, we propose a new approach that combines the advantages of different task allocation algorithms like Round robin algorithm, and Random allocation with different threshold techniques like the VM utilization and the number of allocation counts using least connection mechanism. We performed extensive simulations and experiments that augment different scheduling policies to overcome the resource utilization problem without compromising other performance measures like makespan and execution time of the tasks. The proposed system provided better results compared to the original round robin as it takes into consideration the dynamic state of the system.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.343-356
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• 2022

As a part of round robin analysis to develop a finite element elastic-plastic seismic analysis procedure for nuclear safety class 1 components, a series of parametric analyses was carried out on the simulated pressurizer surge line system model to investigate sensitivity of the analysis results to finite element analysis variables. The analysis on the surge line system model considered dynamic effect due to the seismic load corresponding to PGA 0.6 g and elastic-plastic material behavior based on the Chaboche combined hardening model. From the parametric analysis results, it was found that strains such as accumulated equivalent plastic strain and equivalent plastic strain are more sensitive to the analysis variables than von Mises effect stress. The parametric analysis results also identified that finite element density and ovalization option in the elbow elements have more significant effect on the analysis results than the other variables.

• Polymer Science and Technology
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• v.14 no.6
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• pp.748-754
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• 2003

• Nuclear industry
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• v.22 no.6 s.232
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• pp.71-81
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• 2002

• Geotechnical Engineering
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• v.21 no.4
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• pp.22-36
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.345-345
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• 2007

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.348-348
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• 2007

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1207-1214
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• 2002

A scheduling scheme for high speed networks requires a low time complexity to schedule packets in a packet transmission time. High speed networks support a number of connections, different rates for each connection and variable packet length. Conventional round robin algorithms have a time complexity of O(1), but their short time fairness, latency and burstiness depend on the quantum of a connection due to serving several packets for a backlogged connection once a round. To improve these properties, we propose in this paper an efficient packet scheduling scheme which is based on the credits of a connection and has a time complexity of O(1). We also analyzed its performance in terms of short time fairness, latency and burstiness. The analysis results show that the proposed scheme can improve the performance compared with traditional round robin schemes. The proposed scheme can be easily utilized in high speed packet networks.