• Journal of KIISE:Databases
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• v.36 no.3
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• pp.235-246
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• 2009

As demands intending to treat an access control on a client side that was conventionally controlled at a server are surged. it needs a way to treat query processing in effective and secure manners in an environment that has limited resources. Because the access control having been previously performed was only focused on safety, there was little effort to consider the access control in terms of efficiency. Researches about security including access control are started as the security issues are cropped up in a recent stream environment. This paper proposes a method for efficient and secure query processing of XML data streams like a PDA and a portable terminal at the client that is in limited resources. Specifically, this study suggests (1) an access control processing that possesses small overhead for attaining a secure result in a limited memory and (2) a way to enhance the performance, finding the parts being capable of optimizing in each processing step for offsetting the overhead caused by an addition of the access control processing. Superiority of the new method was analyzed by experiment.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.19-27
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• 2011

Access control that has been previously performed mainly on safety, and thus not much effort has been done to consider access control in terms of efficiency. This paper proposes a method for an efficient and secure query processing of XML data streams, such as a personal digital assistant and a portable terminal, at the client side with limited resources. Specifically, this paper proposes an access control processing that possesses a small overhead for attaining a secure result with limited memory and a method to enhance the performance, finding the parts capable of optimizing each processing step for offsetting the overhead caused by the addition of access control processing. The superiority of the new method is analyzed through an experiments.

• The KIPS Transactions:PartD
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• v.16D no.1
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• pp.27-42
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• 2009

In realizing ubiquitous computing, techniques of efficiently using the limited resource at client such as mobile devices are required. With a mobile device with limited amount of memory, the techniques of XML stream query processing should be employed to process queries over a large volume of XML data. Recently, several techniques were proposed which fragment XML documents into XML fragments and stream them for query processing at client. During query processing, there could be great difference in resource usage (query processing time and memory usage) depending on how the source XML documents are fragmented. As such, an efficient fragmentation technique is needed. In this paper, we propose an XML fragmentation technique whereby resource efficiency in query processing at client could be enhanced. For this, we first present a cost model of query processing over XML fragment stream. Then, we propose an algorithm for resource-efficient XML fragmentation. Through implementation and experiments, we showed that our fragmentation technique outperformed previous techniques both in processing time and memory usage. The contribution of this paper is to have made the techniques of query processing over XML fragment stream more feasible for practical use.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.5
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• pp.1421-1444
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• 2012

Mobile devices such as Android devices are emerging as a convenient client computing device with mobility and context-sensing capability. However, the computing power and hardware resource of the devices are limited due to their small form-factor. Consequently, large-scaled applications could not be deployed on these devices. Nonetheless, if the large-scaled applications are deployed and executed on the devices, high performance of the applications cannot be guaranteed. To remedy the limitation in terms of performance, it is inevitable to let some heavy-weight functionality executed on the server side and let a client application invoke the functionality in the server. To realize this kind of mobile applications, we adopt well-defined architecture design principles; being thin-client, being layered with Model-View-Controller (MVC), and being balanced between client side and server side. By adopting the principles, we propose a unique, ideal and practical architecture for mobile applications, called balanced MVC architecture. By considering the principles, key design considerations of realizing balanced MVC architecture lie in functionality partitioning. Hence, we define key criteria of determining the degree of performance. And, we define a method to design a balanced MVC architecture which embodies functionality partitioning for high performance, and a simulation-based evaluation method of balanced MVC architectures.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.379-388
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• 2007

With proliferation of computer and wireless network technology, it is common to access Internet through wireless network using mobile device. Ratio of using streaming media out of many applications through Internet is increasing not only in wired network but also in wireless network. Streaming media is much bigger than other contents and requires more network bandwidth and more computing resources. However mobile devices hate relatively poor computing resource and low network bandwidth. If media streaming service is provided for mobile devices without any consideration about network bandwidth and computing power, it is hard for the client to get high qualify service. Since mobile device is supported with very limited energy from the battery, media streaming should be adjusted to varying energy state of mobile device in realtime to ensure complete playback of streaming media. In this paper, we propose DFRC to provide high qualify service to mobile client through wireless network by controlling the number of frames transmitted to client based on computing resource and energy state of mobile device.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.456-459
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• 2009

Sensor network has been a hot research topic for the past decade and has moved its phase into using multimedia sensors such as cameras and microphones [1]. Combining many types of sensor data will lead to more accurate and precise information of the environment. However, the use of sensor network data is still limited to closed circumstances. Thus, in this paper, we propose a web-service based framework to deploy multimedia sensor networks. In order to unify different types of sensor data and also to support heterogeneous client applications, we used ROA (Resource Oriented Architecture [2]).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1179-1185
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• 2013

Trend of next generation satellite communication network is distribution and enlargement of network structure with increased network terminals, and traffic which use satellite communication is increasing and frequently occurring. Under specific satellite communication environment that various communication device dynamically forms a network domain and frequently exchanges the data, data-centric publish/subscribe data exchange is more suitable than server/client data exchange. So, this paper analyze DDS performance for application of DDS standard to distribution network management system which aims to efficiently manage limited satellite resource, and also this paper covers comparative study on DDS and SNMP(server/client data exchange). Study compares DDS and SNMP using OPNET, and result of study is analyzed from a network layer performance perspective.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.115-120
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• 2013

Recently, Virtualization technology is moving the desktop environment from its place a mobile platform environment, personal and businesses, academia, and lacked security and in a team environment brought about many changes are coming. In this environment, a representative of VMware's MVP solution and Enterporid Divide. But, another issue is that these mobile virtualization technologies in an environment of limited resources and performance constraints, have become its application virtualization technology to improve the weaknesses of the mobile platform. In this paper, proposed for client-based desktop application virtualization infrastructure, bring it to the Android environment, weaknesses of the existing paper was user area limitations of the desktop environment with application virtualization, program execution android application virtualization launcher was improved through increased resource allocation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.598-612
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• 2004

Client requests have increased with the improvement of network resources at client side, whereas network resources at server side could not keep pace with the increased client request. Therefore, it is primary factor of the Qos that efficiently utilize network resources at server side. In this paper, we proposed a new model that peer-to-peer transfer scheme for partial multimedia stream based on CIWP which it decrease server network bandwidth by utilizing client disk resources saves additional server network resources. Especially, adapting Threshold_Based Multicast scheme guarantees to do that data transfer within clients never exceed service time of previous peer by restriction of which data size transferring from previous peer less than data size transferring from server. Peer-to-peer transfer within clients is limited in same group classified as ISPs. Our analytical result shows that proposed scheme reduces appling network resources at server side as utilizing additional client disk resource. furthermore, we perform various simulation study demonstrating the performance gain through comparing delay time and proportion of waiting requesters. As a result, when we compared to Threshold_Based Multicast scheme, the proposed scheme reduces server network bandwidth by 35%.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.435-447
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• 2004

For VOD systems, it is important to provide QoS to more users under the limited resources. To analyze QoS issues in real environment, we implement clustered VOD server and embedded client system based on the Linux open source platform. The parallel processing of MPEG data, load balancing for nodes and VCR like functions are implemented in the server side. To provide more user friendly interface, the general TV is used for a VOD client's terminal and the embedded board is used supporting for VCR functions. In this paper, we measure the performance of the implemented VOD system under the various user requirement features and evaluate the sources of performance limitations. From these analyses, we propose the dynamic admission control method based on the availability memory and network bandwidth. The proposed method enhances the utilization of the system resource for the more QoS media streams.