• Journal of Communications and Networks
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• v.17 no.3
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• pp.306-320
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• 2015

Due to an explosive growth in services running in different datacenters, there is need for service selection and routing to deliver user requests to the best service instance. In current solutions, it is generally the client that must first select a datacenter to forward the request to before an internal load-balancer of the selected datacenter can select the optimal instance. An optimal selection requires knowledge of both network and server characteristics, making clients less suitable to make this decision. Information-Centric Networking (ICN) research solved a similar selection problem for static data retrieval by integrating content delivery as a native network feature. We address the selection problem for services by extending the ICN-principles for services. In this paper we present Queue and Latency, a network-driven service selection algorithm which maps user demand to service instances, taking into account both network and server metrics. To reduce the size of service router forwarding tables, we present a statistical method to approximate an optimal load distribution with minimized router state required. Simulation results show that our statistical routing approach approximates the average system response time of source-based routing with minimized state in forwarding tables.

• Journal of Chest Surgery
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• v.35 no.3
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• pp.209-216
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• 2002

Background: Valvular heart disease is still the most common health problem in Korea. By the end of the year 1999, there has been 94,586 cases of open heart surgery since the first case in 1958. Among them, 36,247 cases were acquired heart diseases and 20,704 of those had valvular heart disease. But there was no database system and every surgeon and physician had great difficulties in analysing and utilizing those tremendous medical resources. Therefore, we developed a valve registry database program and utilize it for risk factor analysis and so on. Material and Method: Personal computer-based multiuser database program was created using Microsoft AccessTM. That consisted of relational database structure with fine-tuned compact field variables and server-client architecture. Simple graphic user interface showed easy-to-use accessability and comprehensibility. User-oriented modular structure enabled easier modification through native AccessTM functions. Infinite application of query function aided users to extract, summarize, analyse and report the study result promptly. Result: About three-thousand cases of valve replacement procedure were performed in our hospital from 1968 to 1999. Total number of prosthesis replaced was 3,700. The numbers of cases for mitral, aortic and tricuspid valve replacement were 1600, 584, 76, respectively. Among them, 700 patients received prosthesis in more than two positions. Bioprosthesis or mechanical prosthesis were used in 1,280 and 1,500 patients respectively Redo valve replacements were performed in 460 patients totally and 40 patients annually Conclusion: Database program for registry of valvular heart disease was successfully developed and used in personal computer-based multiuser environment. This revealed promising results and perspectives in database management and utilization system.