• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.738-749
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• 2011

In this paper, we study QoS(Quality of Service) control protocols and the effect using MAC/PHY parameters of client device in mobile network. We proposes the way of controling the bit-rate by estimating the channel condition of the client with measured MAC/PHY parameters which is sent from the client. With the proposed method, more accurate available bit-rate can be estimated compared to conventional protocol, RTCP(Real-time Transport Control Protocol). The accurate bit-rate estimation can decrease wasted bit-rate and transport delay. In the result of the advantages, the transported video quality can be enhanced. In this paper, we show the effects of enhancement using client's the field data measured in WiMAX.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.517-521
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• 2008

A worm is a malware that propagates quickly from host to host without any human intervention. Need of early worm detection has changed research paradigm from signature based worm detection to the behavioral based detection. To increase effectiveness of proposed solution, in this paper we present mechanism of detection and prevention of worm in distributed fashion. Furthermore, to minimize the worm destruction; upon worm detection we propagate the possible attack aleγt to neighboring nodes in secure and organized manner. Considering worm behavior, our proposed mechanism detects worm cycles and infection chains to detect the sudden change in network performance. And our model neither needs to maintain a huge database of signatures nor needs to have too much computing power, that is why it is very light and simple. So, our proposed scheme is suitable for the ubiquitous environment. Simulation results illustrate better detection and prevention which leads to the reduction of infection rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1152-1157
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• 2002

In this paper, a detailed procedure of development for an AAL2 processor widely used in voice gateway application is introduced. The processor supports CPS and SSCS with voice service and framed mode data service. It provides 4 ATM virtual connections, which include 1020 AAL2 channels. The processor has one UTOPIA Level 1 interface for an ATM cell interface and 4 TDM ports for a voice channel interface. The TDM ports carry PCM/ADPCM voice streams. Most AAL2 processors are implemented as software, or hardware and software, so its latency is large. But this processor has very low latency as to CPS and SSCS because all of them are implemented in hardware. Also, it allows not only loopback and switching of CPS packets, but loopback and switching of TDM channels. The key feature is that the internal structure of the CPS and SSCS in this processor seems like as each software function, so they are called whenever they are required. In addition, they are reusable for another design and are scalable for more channels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.219-222
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• 2013

Recently, rapid innovation of Smartphone is changing the paradigm of our daily life. With the launch of Apple iPhone, there is an explosion of interest in Smartphone itself as well as Internet-based services using Smartphone are being revitalized. Smartphone users, opinion experts more than 99 percent of the economically active population is using, it has reached the saturation past the early stages of formation. Smartphone is equipped with a general purpose OS possible the implementation of high performance environment similar level as a personal computer. Also, it is a mobile communication terminal scalable which can be removed or installed various applications. New information technology like Smartphone gives us a very important and interesting research issue that is to find and prove the factors influencing the purchase intention. At this point, study identifying on the influence factors to the behavioral intention of Smartphone is very important. This study was targeted a total of 99 research papers that are setting up the related Smartphone in among the research papers published in domestic academic journals since 2008. Empirical research related behavioral intention using was summarized on the papers 76.

• Journal of Digital Convergence
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• v.12 no.5
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• pp.1-12
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• 2014

Recently, the need for non-stop service is increasing by the business mission-critical Internet banking, e-payment, e-commerce, home shopping, securities trading, and petition business increases, clustered in a single database of existing, redundant research on high-availability technologies related to technique, etc. is increasing. It provides an API based on the Active Log in addition to the technique of redundancy, ALTIBASE$^{TM}$ Log Analyzer (below, ALA), provides scalability and communication of the same model or between heterogeneous. In this paper, we evaluated the performance of ALA by presenting the design of the database system that you can use the ALA, to satisfy all the synchronization features high scalability and high availability, real-time.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.67-75
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• 2009

Multi-layered video coding that provides scalability across the visual content has emerged for easily adaptive service over current heterogeneous network. However, the network is still error prone environment so that video service may suffer packet loss or erroneous decoding of the video. Especially distortion caused by the burst error may propagate to several pictures until intra refreshing, which will raise a terrific degradation of picture quality. To overcome the problem at terminal independently, we propose a new error concealment algorithm for the multi-layered video coding. The proposed method uses the similarity of between layers in the multi-layered video coding and POCS (Projections Onto Convex Sets) which is a powerful error concealment tool, but heavily dependent on initial values. To find adequate initial value which can reduce iteration times as well as achieve high performance, we took consideration into both features of layered approach coding and the correlation in neighbor blocks. The simulation results show that the proposed concealment method works well.

• The KIPS Transactions:PartC
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• v.10C no.7
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• pp.915-922
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• 2003

The Grid is an infrastructure to connect heterogeneous resources that are scattered over areas with high-speed network and to cooperate with each other. To support Grid applications, network resources should be managed, since the network has to be safe and reliable. The Grid Monitoring Architecture Working Group (GMAWG) of the Global Grid Forum (GGF) proposed an effective architecture to be scalable across wide-area networks and encompass a large number of heterogeneous resources. In this paper, we describe the design and implementation of Grid network monitoring system based on the GMA for practical network management. By this system, network operations center can form a management system flexibly and scalably for Grid network.

• Journal of Digital Contents Society
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• v.15 no.5
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• pp.595-602
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• 2014

Cloud computing is already well known paradigm that a support computing resource flexible and scalable to users as the want in distributed computing environment. Actually, cloud computing can be implemented and provided by virtualization technology. Also, various products are released or under development. In this paper, we built the teaching practice system using cloud computing and evaluated practical environment which constructed over a virtual machine. Virtualization-based cloud computing provides optimized computing resources, as well as easy to manage practical resource and result. Therefore, we can save the time for configuration of practice environment. In the view of faculty, they can easily handle the practice result. Also, those practice condition reuse comfortably and apply to various configuration simply. And then we can increase capabilities and availabilities of limited resources. Additionally, we measure the performance requirements for educational applications through evaluation of virtual-based teaching practical system in advance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.178-188
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• 2016

The traffic in the wired and wireless networks has increased exponentially because of increase of smart phone and improvement of PC performance. Multimedia services and file transmission such as Facebook, Youtube occupy a large part of the traffic. CDN is a technique that duplicates the contents on a remote web server of content provider to local CDN servers near clients and chooses the optimal CDN server for providing the content to the client in the event of a content request. In this paper, the content request message between CDN servers and the client used the SCRP algorithm utilizing the MST algorithm and the traffic throughput was optimized. The average response time for the content request is reduced by employing HC_LRU cache algorithm that improves the cache hit ratio. The proposed SCRP and HC_LRU algorithm may build a scalable content delivery network system that efficiently utilizes network resources, achieves traffic localization and prevents bottlenecks.

• The KIPS Transactions:PartD
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• v.8D no.6
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• pp.735-746
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• 2001

As collaborative works have been spread over the internet, the need for information systems providing virtual workspaces has grown rapidly. Through virtual workspaces, the members participating in those collaborative works share and exchange their information effectively. It is desirable that these systems can be extended according to various requests of users, providing reliable services. In this paper, we describe a group of components for supporting collaboration and the iPlace (internet workPlace) system developed with those components. The iPlace system provides effective sharing and reusing of information among the members of collaborative groups through personal workspaces-the private spaces on the Web for each user and shared workspaces-the shared spaces for each of those groups. In addition, implemented with EJB technology, it provides highly scalable and reliable services.