• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.107-114
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• 2002

In these days, rapid advances of the computer system and the high speed network have made the multimedia services popularized among various applications and services in the internet. Internet live broadcasting, a part of multimedia services, makes it possible to provide not only existing broadcasting services including audio and video but also interactive communications which also expand application scopes by freeing from both temporal and spatial limitation. In the Paper, an interned Personal-live broadcasting server system is developed by allowing individual users to actively create or join live-broadcasting services with such basic multimedia devices as a PC camera and a sound card. As the number of broadcasters and participants increases, concurrent multiple channels are established and groups are to be expanded. The system should also guarantee High Availability (HA) for continuous services even in the presence of partial failure of the cluster. Furthermore, a transmission mode switching is supported to consider network environments in the user system.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.232-238
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• 2003

Traditional operating systems use a virtual memory to provide users with a bigger memory than a physical memory. The virtual memory augments the insufficient physical memory by the swap device. Since disks are usually used as the swap device, the cost of a page fault is relatively high compared to the access cost of the physical memory. Recently, numerous papers have investigated the Network RAM in order to exploit the idle memory in the network instead of disks. Since today's distributed systems are interconnected with high-performance networks, the network latency is far smaller than the disk access latency In this paper we design and implement the Network RAM using block device driver on Linux. This is the first implementation of the Network RAM on Linux. We propose the new reliability method to recover the page when the other workstation's memory is damaged. The system using the Network RAM as the swap device reduces the execution time by 40.3% than the system using the disk as the swap device. The performance results suggest that the new reliability method that use the processor more efficiently has the similar execution time with others, but uses smaller server memory and generates less message traffic than others.