• Journal of KIISE:Databases
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• v.29 no.6
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• pp.464-476
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• 2002

Main-memory database systems which reside entire databases in main memory are suitable for high-performance real-time transaction processing. If two-phase locking(2PL) as concurrency control protocol is used for the transactions accessing main-memory databases, however, the possibility of lock conflict will be low but lock operations become relatively big overhead in total transaction processing time. In this paper, We designed a real-time static locking(RT-SL) protocol which minimizes lock operation overhead and reflects the priority of transactions and we implemented it on a main-memory real-time database system, Mr.RT. We also evaluate and compare its performance with the existing real-time locking protocols based on 2PL such as 2PL-PI and 2PL-HP. The extensive experiments reveal that our RT-SL outperforms the existing ones in most cases.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.971-980
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• 2018

Using the concept of quasi-static decomposition and using three-noded isoparametric locking-free element, this article presents a formulation of the finite element method for Timoshenko beam subjected to spatially different time-dependent motions at supports. To verify the validity of the formulation, three fixed-hinged beams excited by the real seismic motions are examined; one is a slender beam, another is a stocky one, and the other is an intermediate one. The numerical results of time histories of motions of the three beams are compared with corresponding analytical solutions. The internal loads such as bending moment and shearing force at a specific time are also compared with analytic solutions. These comparisons show good agreements. The comparisons between static components of the internal loads and the corresponding total internal loads show that the static components predominate in the stocky beam, whereas the dynamic components predominate in the slender one. Thus, the total internal loads of the stocky beam, which is governed by static components, can be predicted simply by static analysis. Careful numerical experiments indicate that the fundamental frequency of a beam can be used as a parameter identifying such a stocky beam.