• Journal of KIISE:Information Networking
• /
• v.30 no.1
• /
• pp.9-16
• /
• 2003

In this paper, we propose a method for supporting VCR operations in a patching based multicast VOD system. Random access, pause and resume operations are supported in our system, and the channel and session scheduling algorithms for the VCR operations are proposed. When it is necessary to join a sharable multicast channel in the admission control for the VCR operations, the patching technique, which shares an on-going regular channel and allocates a new patching channel for the missing data, is used. Therefore, unlike the previous approach that allocates an excessive number of I-channels, service latency is minimized and channel usage is optimized in our system. Moreover buffered data. which is saved in disk during patching, is reused to prevent unnecessary patching channel allocation. For this. the patching management information is extended and a buffed data management scheme is proposed. In our system, the First-Come-First-Served scheduling is used to inform clients the service latency for the VCR operations immediately.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.7
• /
• pp.65-72
• /
• 2009

This paper proposed VCR cryptographic algorithm that adapted in TCP/IP protocol architecture and wire/wireless communication network environments. we implemented by hardware chip level because proposed VCR cryptographic algorithm perform scalable & reconfigurable operations into the security system. Proposed VCR cryptographic algorithm strengthens security vulnerability of TCP/IP protocol and is very profitable real-time processing and encipherment of high-capacity data and multi-user communication because there is important purpose to keep security about many user as that have variable round numbers function in network environments.

• Journal of the Korea Computer Industry Society
• /
• v.7 no.3
• /
• pp.217-226
• /
• 2006

Intensive studies have been made in the area of N-VOD server Multimedia files in the N-VOD sever are characterized with the large volume of data, the requirements of synchronization and real-time playback of streams. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Buffer size and disk bandwidth. we propose a efficient VCR-LIKE operations and buffer, disk scheduling policy for multimedia services with management of VOD sever resources. Simulation results show that the rate of buffer usage and service time of proposed scheme are about 18% performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.

• Journal of KIISE:Computing Practices and Letters
• /
• v.6 no.3
• /
• pp.299-310
• /
• 2000

In this paper, we designed and implemented a personal VOD server using multi-thread for the real-time services of video data to the users. The system consists of service manager, disk manager, and network manager. The service manager controls the user admission to the system using the VBR(Variable Bit Rate) characteristics of MPEG (Moving Picture Experts Group) video data. The disk manager provides the functions for VCR-like operations. The disk manager reads blocks from the disk by the size of GOP(Group of Pictures) and buffers the data to the user's thread. The network manager uses TCP/IP for the communication between the server and the client. The communication starts from the client and the VOD server must respond to this request. The implemented personal VOD system shows an acceptable performance.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2005.05a
• /
• pp.740-745
• /
• 2005

Selective assembly is a method to find out appropriate matching pairs to be assembled to enhance the quality of the product. This study proposes an algorithm to select and match the components with two performance characteristics: at first, the number of matchable mates are calculated for each components. A matchable mate is defined to be the one of which the values of each performance characteristics lie in a rectangular mesh originated from the component under consideration. And the highest priority is given to the item with smallest number of matchable mates. The item of highest priority is matched to the one with smallest number of matchable mates among them. To find out the mates for the unmatched items, the mesh size is enlarged at the next iteration. Beginning with a small mesh, the procedure is repeated until the mesh covers the tolerance intervals of each performance characteristics. A VCR head case is analyzed.

• Journal of Digital Contents Society
• /
• v.13 no.4
• /
• pp.567-574
• /
• 2012

In this paper, we propose a buffering scheme to improve the performance by adaptively adjusting the length of the buffering period according to the degree of data duplication among peers that belong to each specific playback period in P2P live streaming systems. To do so, we first assign all the peers into many groups depending on their playback time positions. We then determine the length of their buffering periods according to the number of peers belonging to each group. That is, we increase the length of the buffering periods when much buffered data are duplicated among peers within a group while we decrease it when few buffered data are duplicated. By simulation experiments, we show that our proposed buffering scheme can improve the performance significantly compared to the fixed length buffering scheme that have been employed in the existing mesh-based P2P systems.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.9B
• /
• pp.1643-1651
• /
• 1999

Video-On-Demand (VOD) is expected to provide the user with interactive operations such as VCR functions. In particular, fast scan functions like “Fast Forward” of “Fast Backward” for a certain speedup playback are required. Since they require a significant amount of system resources, schemes to reduce bandwidth requirements for the network or disk are needed. In MPEG standard, Group-of-Pictures (GoP) is a random access unit which can be decoded independently. Since storing and transmitting a video stream based on GoP is efficient, it is practical to support fast scan functions based on GoP. In this paper, we present a dynamic transmission scheduling scheme to support fast scan functions with m-times normal playback rate for a stored video. The proposed scheme writes a transmission schedule whenever user requests a fast scan function. That is, the scheme constructs the data set to be smoothed by skipping GoPs according to a given speedup factor, and then writes the transmission schedule by applying a bandwidth smoothing. Finally, the scheme restarts the transmission of video data to a client according to the new schedule. The proposed scheme results in speeding up the playback rate by utilizing “GoP skipping”, and then reduces the computational overhead by applying a bandwidth smoothing based on GoP.