Young Myoung Ko

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In this paper, we consider time-varying multi-server queues with abandonment and retrials. For their performance analysis, fluid and diffusion limits utilizing strong approximations have been widely used in the literature. Although those limits are asymptotically exact, they may not accurately approximate performance of multi-server queues even if the(More)
Data centers consume a phenomenal amount of energy which can be significantly reduced by appropriately allocating resources using technologies such as virtualization, speed scaling and powering off servers. We propose a unified methodology that combines these technologies under a single framework to efficiently operate data centers. In particular, we(More)
BACKGROUND Smartphone-based assessment may be a useful diagnostic and monitoring tool for patients. There have been many attempts to create a smartphone diagnostic tool for clinical use in various medical fields but few have demonstrated scientific validity. OBJECTIVE The purpose of this study was to develop a smartphone application of the International(More)
— In this paper we consider a distributed peer-based system with a centralized controller responsible for managing the peers. For this system customers request large volumes of information such as video clips which instead of retrieving from a centralized repository of a parent organization are obtained from peers that possess the clips. Peers act as(More)
Consider a firm that sells on-line multimedia content. In order to manage costs and quality of service, this firm maintains a peer-network whereby users download files from other peers that have downloaded them in the past. The scenario can be modeled as a queueing system where the number of servers varies over time. We develop analytical models based on(More)
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