• Journal of Korea Multimedia Society
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• v.16 no.6
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• pp.678-688
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• 2013

Different Different from a single attack, in DDoS Attacks, the botnets that are distributed on network initiate attacks against the target server simultaneously. In such cases, it is difficult to take an action while denying the access of packets that are regarded as DDoS since normal user's convenience should also be considered at the target server. Taking these considerations into account, the DDoS botnet detection system that can reduce the strain on the target server by detecting DDoS attacks on each user network basis, and then lets the network administrator to take actions that reduce overall scale of botnets, has been implemented in this study. The DDoS botnet detection system proposed by this study implemented the program which detects attacks based on the database composed of faults and abnormalities collected through analyzation of hourly attack traffics. The presence of attack was then determined using the threshold of current traffic calculated with the standard deviation and the mean number of packets. By converting botnet-based detection method centering around the servers that become the targets of attacks to the network based detection, it was possible to contemplate aggressive defense concept against DDoS attacks. With such measure, the network administrator can cut large scale traffics of which could be referred as the differences between DDoS and DoS attacks, in advance mitigating the scale of botnets. Furthermore, we expect to have an effect that can considerably reduce the strain imposed on the target servers and the network loads of routers in WAN communications if the traffic attacks can be blocked beforehand in the network communications under the router equipment level.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.582-594
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• 2004

In school PC labs or other educational purpose PC labs with a few dozens of PCs, computers are configured in a distributed architecture so that they are set up, maintained and upgraded separately. As an alternative to the distributed architecture, we can consider a thin-client computing environment. In a thin-client computing environment, client side devices provide mainly I/O functions with user friendly GUI and multimedia processing support whereas remote servers called terminal server provide computing power. In order to support many clients in the environment, a cluster of terminal servers can be configured. In this architecture, it is difficult due to the characteristics of terminal session persistence and different pattern of computing usage of users so that the utilization of terminal server resources becomes low. To overcome this disadvantage, we propose an adaptive terminal cluster where terminal servers ,ire partitioned into groups and a terminal server in a light-loaded group can be dynamically reassigned to a heavy-loaded group at run time. The proposed adaptive scheme is compared with a generic terminal service cluster and a group based non-adaptive terminal server cluster. Experimental results show the effectiveness of the proposed scheme.

• Journal of Korea Multimedia Society
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• v.9 no.7
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• pp.927-937
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• 2006

Auto-playing programs are often used in behalf of human players in MMORPG(Massively Multi-player Online Role Playing Game). By playing automatically and continuously, it helps to speed up the game character's level-up process. However, the auto-playing programs, either software or hardware, do harm to games servers in various ways including abuse of resources. In this paper, we propose a way of detecting the auto programs by analyzing the window event sequences produced by the game players. In our proposed method, the event sequences are transformed into a set of attributes, and the Decision Tree learning is applied to classify the data represented by the set of attribute values into human or auto player. The results from experiments with several MMORPG show that the Decision Tree learning with proposed method can identify the auto-playing programs with high accuracy.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.130-137
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• 2010

An advancement and wide use of portable multimedia devices make it easy to spread digital sound source, enabling users to use portable multimedia devices and search and enjoy digital sound sources and related contents. In opposition the off-line musical service market with CD stagnates gradually and in the crisis where the off-line musical service market vanishes away. In this paper, we propose the mobile music album information retrieval system which combines the barcode and a cellular phone musical service. To get digital sound sources and related information from music albums, the proposed retrieval system uses one-dimensional barcodes attached to music albums and obtains information on related albums from the sound source servers. Also, to reflect user preferences in search results, the system uses search frequency by music album, and searches albums in music genres selected by users in the order of the recent preference. The proposed mobile music album retrieval system is implemented on the basis of WIPI, and is now providing pilot services.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.7-13
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• 2017

In recent years, cloud computing technology has been socially emerged that provides services remotely as various devices are used. However, there are increasing attempts by some users to provide cloud computing services with malicious intent. In this paper, we propose a property - based multi - level hierarchical approach to facilitate authentication access for users accessing servers in cloud environment. The proposed method improves the security efficiency as well as the server efficiency by hierarchically distributing a set of attribute values by replacing the order of the user 's attribute values in the form of bits according to a certain rule. In the performance evaluation, the proposed method shows that the accuracy of authentication according to the number of attributes is higher than that of the existing method by an average of 15.8% or more, and the authentication delay time of the server is decreased by 10.7% on average. As the number of attributes increases, the average overhead change is 8.5% lower than that of the conventional method.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.287-292
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• 2001

Multimedia service systems should have efficient capacity to serve the growing clients and new data. In the general streaming services, users can endure the small amount of time delay at the beginning of service. But they want to have good quality of service. A streaming server tries to transfer video files to clients from a repository of files in real time. The server must guarantee concurrent and uninterrupted delivery of each video stream requested from clients. To achieve its purpose, many stream servers adopt multi-processors, sufficient memory, and RAID or SAN in their systems. In this paper, we propose a Linux-based parallel media streaming server. It is superior to the other systems in the storing structure, fault-tolerance, and service capacity. Since this system supports the web interlace, users can operate easily through the www. This system uses unique striping policy to distribute multimedia files into the parallel storage nodes. If a service request occurs, each storage node transmits striped files concurrently to the client. Its performance is better than the single media streaming service because of the parallel architecture.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1106-1116
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• 2007

Recently e-commerce trade on the web has grown rapidly in scale and complexity, just as web site designs and web servers have become more complicated. In view of these complexities, it is obviously difficult to analyse web user's data since they web users employ so many different web paths. The existing association rule investigation algorithms identify all items with a high correlation. However even though users often only want to find items in which they have interest, it is still difficult to find the rules they want out of all of the many association rules found by existing algorithms. In this paper, we propose a system linking each node with the sequence association rule, linking all routes after finding a path corresponding to a user with the association rule-one of the data mining techniques which identify user patterns in web user paths. The suggested system helps us construct individualized or customer-subdivided sites using the sequence association rule in order to harmonize the paths of web users with user characters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2202-2211
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• 2006

EXT3NS is a special-purpose file system for large scale multimedia streaming servers. It is built on top of streaming acceleration hardware device called Network-Storage card. The EXT3NS file system significantly improves streaming performance by eliminating memory-to-memory copy operations, i.e. sending video/audio from disk directly to network interface with no main memory buffering. In this paper, we design and implement a buffer cache mechanism, called PMEMCACHE, for EXT3NS file system. We also propose a buffer cache replacement method called ONS for the buffer cache mechanism. The ONS algorithm outperforms other existing buffer replacement algorithms in distributed multimedia streaming environment. In EXT3NS with PMEMCACHE, operation is 33MB/sec and random read operation is 2.4MB/sec. Also, the buffer replacement ONS algorithm shows better performance by 600KB/sec than other buffer cache replacement policies. As a result PMEMCACHE and an ONS can greatly improve the performance of multimedia steaming server which should supportmultiple client requests at the same time.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.518-520
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• 2006

Due to the rapid popularization of mobile multimedia devices and the Internet as well as the realization of high-speed data transmission and large-volume data recording media, high quality content distribution and ubiquitous information services are making progress and a new type of information distribution and network sharing service has gradually emerged into the market. It is capable of utilizing terabyte sized home servers also in private homes. Under these circumstances, in distribution of content over shared networks, it is crucial to establish DRM (Digital Rights Management) technologies to protect the content from illegal copying and usage. A truly successful DRM system must be built on open worldwide specifications and provide maximum interoperability and user acceptance. An open interoperability of DRM is able to construct highly expandable PKI based DRM, targeting usage between systems, considering the expansion of recent content distribution services and clients This document gives protocol specifications for the exchange of rights information between the DRM module, description of specifications for rights information and encrypted content formats.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.476-481
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• 2012

Recently, QoS/QoE technology as a part of the HTTP-based adaptive streaming technology has attracted attention. In this paper, we find out HTTP-based adaptive and dynamic streaming technology. It is based on a dynamic adaptive streaming system over HTTP, which is designed and implemented. The system consist of conversion by the bit rate of MPEG2-TS files, division of segment, creation of MPD(Media Presentation Description) and bitrate's player through analysis of MPD File between servers and clients in network environments of dynamic and adaptive. This diverse network environments, continuous and smooth playback of video will be used in various multimedia fields.