• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.129-136
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• 2006

We propose a new data carousel scheduling algorithm for on-demand data broadcasting in DMB. The server divides data items into two sets named hot and cold, according to request statistics from clients. When constructing a data carousel, hot items are placed periodically with their upper limit of broadcasting frequency. If there are empty slots after placing hot items, cold items with high request ratio are placed until the carousel is full. A cold item is broadcast only once in the caroulsel. For the response on clients' requests, our proposed scheme is shown to have high success ratio with short waiting time.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.4
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• pp.242-255
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• 2006

In the recent years, Popularization of mobile devices such as Smart Phones, PDAs and MP3 Players causes rapid increasing necessity of Power management technology because it is most essential factor of mobile devices. On the other hand, despite low price, hard disk has large capacity and high speed. Even it can be made small enough today, too. So it appropriates mobile devices. but it consumes too much power to embed In mobile devices. Due to these motivations, in this paper we had suggested methods of minimizing Power consumption while playing multimedia data in the disk media for real-time and we evaluated what we had suggested. Strict limitation of power consumption of mobile devices has a big impact on designing both hardware and software. One difference between real-time multimedia streaming data and legacy text based data is requirement about continuity of data supply. This fact is why disk drive must persist in active state for the entire playback duration, from power management point of view; it nay be a great burden. A legacy power management function of mobile disk drive affects quality of multimedia playback negatively because of excessive I/O requests when the disk is in standby state. Therefore, in this paper, we analyze power consumption profile of disk drive in detail, and we develop the algorithm which can play multimedia data effectively using less power. This algorithm calculates number of data block to be read and time duration of active/standby state. From this, the algorithm suggested in this paper does optimal scheduling that is ensuring continual playback of data blocks stored in mobile disk drive. And we implement our algorithms in publicly available MPEG player software. This MPEG player software saves up to 60% of power consumption as compared with full-time active stated disk drive, and 38% of power consumption by comparison with disk drive controlled by native power management method.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.247-254
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• 2020

The recent Internet environment is characterized by the explosion of certain types of data, as the data that people want is affected by certain issues. In this paper, we propose a load balancing technique that considers the data generation forms. The concept of this technique is to prioritize some type of data when it suddenly explodes. This is a technique to build an add-on middle box on a switch to monitor packets and give priority to a queue for load balancing. This technique worked when certain types of data exploded. SDN(Software Defined Networking) has the advantage of efficiently managing a number of network equipment. However, load balancing in the SDN environment has not been studied much. Applying the proposed load balancing technique in the SDN environment can save time and budget and easily implement our policies. When the proposed load balancing technique is applied to the SDN environment, it has been found that the techniques we want can be easily applied to the network systems, and that efficient data processing is possible when certain types of data explosion.

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.8-14
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• 2017

In 4G mobile communication, data services of mobile communication began to be provided in earnest. As a result, services such as the internet and multimedia including the video have become the main contents in the recent wireless traffic. Accordingly, research on 5G mobile communication with higher transmission rate has been actively carried out. 5G mobile communication is expected to be based on 4G for compatibility with existing terminals. Therefore, the simulation of this paper is based on 4G and we propose a new user scheduling scheme based on the Max throughput scheduling algorithm to improve system performance. This paper derives the frequency efficiency and fairness to compare the existing user scheduling algorithm with the proposed user scheduling algorithm. The proposed scheme shows better frequency efficiency and fairness than Max throughput in all situations. This paper contributes to the research for improving the system performance of 5G mobile communication technology, and I hope that it will help some of the ongoing standardization work.

• IE interfaces
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• v.23 no.2
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• pp.193-202
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• 2010

The quality of service(QoS) model should be presented with the optimal network design to effectively provide the multimedia data services between users and converged services with mobile or TV in the next-generation Internet. In specific, the method to provide differentiated services for each user is needed in the given Internet node to offer the previously negotiated QoS with the user. In this paper, the performance of the QoS enabling technologies in the differentiated services(DiffServ) network domain is analyzed. The QoS offering model and QoS metrics are presented to analyze the performance of the major scheduling algorithms. Under the real network topology and virtual service scenarios in the university, the NS-2 network simulation based on the discrete-event is performed. The results show that the ratio-based scheduling method is more effective rather than the bandwidth-assignment method.

• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.81-86
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• 2015

This paper suggests heuristic algorithm with linear time complexity to decide the normal and optimal point at minimum loss/maximum profit maximum shortest scheduling problem with additional loss cost and bonus profit cost. This algorithm computes only the earliest ending time for each node. Therefore, this algorithm can be get the critical path and project duration within O(n) time complexity and reduces the five steps of critical path method to one step. The proposed algorithm can be show the result more visually than linear programming and critical path method. For real experimental data, the proposed algorithm obtains the same solution as linear programming more quickly.

• Journal of Korea Multimedia Society
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• v.4 no.1
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• pp.13-28
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• 2001

In a VOD(Vide-On-Demand) system, video data are generally stored in magnetic disk array. In order to provide real-time requirement for data retrieval, video streams must be delivered continuously to the clients such that the delivery of continuous media can be guaranteed in a timely fashion. Compared to the increased performance of processors and networks, the performance of magnetic disk systems have improved only modestly. In order to improve the performance of storage system, disk array system is proposed and used. The array system improves I/O performance by placing disks in parallel and retrieving data concurrently. In this paper, two approaches are considered in order to access the video data in a VOD system, which are CTL(Constant Time Length) and CDL(Constant Data Length) access policies. Disk scheduling policies are also classified into the two categories and compared in terms of the maximum allowable video streams with different degrees of disk array synchronization, under the mixed environments in which both data access policy and disk scheduling policy are considered. Among the compared scheduling policies, LOOK was shown to have the best performance. In terms of degree of disk synchronization, more gain was achieved with large degree of synchronization. In comparisons of performance of CTL and CDL, CTL was proved to have a little superior performance in terms of number of maximum allowable streams.

• Journal of the Korea Society of Computer and Information
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• v.20 no.7
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• pp.33-40
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• 2015

The time slot assignment problem (TSAP) or Satellite Communications scheduling problem (SCSP) for a satellite performs $n{\times}n$ ground station data traffic switching has been known NP-hard problem. This paper suggests $O(n^2)$ time complexity algorithm for TSAP of a satellite that performs $n^2{\times}n^2$ ground station data traffic switching. This problem is more difficult than $n{\times}n$ TSAP as NP-hard problem. Firstly, we compute the average traffic for n-transponder's basic coverage zone and applies ground station exchange method that swap the ground stations until all of the transponders have a average value as possible. Nextly, we transform the D matrix to $D_{LB}$ traffic matrix that sum of rows and columns all of transponders have LB. Finally, we select the maximum traffic of row and column in $D_{LB}$, then decide the duration of kth switch mode to minimum traffic from selected values. The proposed algorithm can be get the optimal solution for experimental data.

• Journal of Korea Multimedia Society
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• v.7 no.4
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• pp.496-504
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• 2004

This paper preposes a various policies and experiment results to select streams in a presentation to be transcoded for mobileterminals after distinguishing the characteristics of streams in the presentation. This applies to the presentation composed of various data streams on a PC server. The rationale of the research is that the stream selection polices for transcoding enhances the speed of presentation in mobile terminals considerably faster than in the case when every stream has to be transcoded. Thus, the thesis suggests a stream selection polices for transcoding based on EPOB (End Point of Over Bandwidth) and aims to lower the requiring bandwidth of the presentation to the network bandwidth as well as to minimize early delay time for the presentation to be played in mobile terminals.

• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.2
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• pp.139-155
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• 2003

The aim of this study is to identify the data traffic capacity of 3G mobile communication networks, especially of cdma2000-1X networks. Three-layered ON/OFF traffic model is used to describe the dynamics of data traffics and the process of data transmission such as packet scheduling. We construct a simulator fully incorporating packet handling process of cdma2000-lX data network as well as three-layered ON/OFF traffic model describing the behavior of source data traffics. To get influence of traffic parameters on performance measures, the extensive simulations were performed for several data sets which are obtained from real trace data or previous studies. The experimental results show that the engineered throughput satisfying QoS criteria is approximately 25% of total capacity. Finally, some proposals to improve the system capacity are followed.