• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.1051-1059
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• 1992

Two types of digital repetitive control systems are analyzed and designed to reduce the error spectrum including not only harmonic but also non-harmonic components. First, a novel gain scheduling algorithm is suggested for conventional and modified repetitive controller is scheduled to reduce the infinite norm of error in frequency domain. For this, the relative error transfer function is mewly defined as the ratio of the error spectrum for the system with a repetitive controller to the error spectrum for the system with a repetitive controller to the error spectrum for the system without a repetitive controller. Secondly, as an alternative of a repetitive control system with the gain scheduling, a repetitive control system with higher order repetitve function is analyzed and designed, where instead of equal weightings, weightings of the higher order repetitive function is determined in such a way that the infinite norm of relative error transfer function is minimized. To show the validities of proposed methods, computer simulation results are illustrated for a typical disk drive head positioning servo system.

• Journal of KIISE:Databases
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• v.29 no.1
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• pp.15-26
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• 2002

Most work on multimedia storage systems has assumed that client will be serviced using a round-robin strategy. The server services the clients in rounds and each client is allocated a time slice within that round. Furthermore, most such algorithms are evaluated on the basis of a tightly coupled cost function. This is the basis of well-known algorithm such as FCFS, SCAN, SCAN-EDF, etc. In this paper, we describe a scheduling module called Request Unifier(RU) that takes as input, a set of client request, and a set of constraints on the desired performance such as client waiting time or maximum disk bandwidth, and a cost function. It produces as output a Unified Read Request(URR), telling the storage server which data items to read and when these data items to be delivered to the clients. Given a cost function, a URR is optimal if there is no other URR satisfying the constraints with a lower cost. We present three algorithms in this paper that can accomplish this kind of request merging and compare their performance through an experimental evaluation.