• Spatial Information Research
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• v.13 no.3 s.34
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• pp.221-237
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• 2005

This study attempts at building a GIS computing environment that incorporates object-relational spatio-temporal database for the time geography model with space-time path, space-time prism and space-time accessibility. The proposed computing environment is composed of ( i ) mobile GIS application for collecting spatio-temporal trajectory data of an individual, ( ii ) spatio-temporal database server that includes time geography model, and (iii) geovisualization client that performs time geographic queries to the spatio-temporal database. The spatio-temporal trajectory data collected by GPS-PDA client is automatically processed and sent to server through data management middleware. The spatio-temporal database implemented by extending a generic DBMS provides spatio-temporal objects, functions, and SQL. The geovisualization client illustrates 3D visual results of the queries about space-time path, space-time prism, and space-time accessibility. This study confirms the possibility of integrating mobile GIS and DBMS for time geography model, and it presents the appropriate database model with spatio-temporal objects and functions that may handle very large data for time geography application.

• The Journal of the Korea Contents Association
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• v.5 no.4
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• pp.212-218
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• 2005

These days, mobile technology is developing very fast. It has increased the usage of the Internet by mobile phones. Nowadays the avatar and game contents services are most popular in mobile phones using the Internet. In this paper, we propose a Client/Server system to combine the animation avatar and e-mail services on SK-VM which are different from simple avatar services. The server which consists of DB (database) module and mail management module is designed in order to manage the information about avatar and the user. The client is designed so as to show the email contents and avatar animation on the mobile phone. This model is intended to reduce the performance overhead on the client as much as possible. We expect that this module would be useful in the mobile phones with limited resources, although the technology is being developed very rapidly.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.608-611
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• 2012

In this paper, a mobile cloud-based agent model is proposed in order to overcome the resource constraints and the difficulties of installing a variety of complex applications in mobile devices. The proposed software architecture overcomes the disadvantages of mobile devices and maximizes usage of cloud services by implementing the function of mobile agent concept. The significant portion of the cloud services is run in the cloud server and the client application implemented in the mobile device can call and control appropriate service from the cloud server. Thus, the inherent weakness of the mobile can be overcome by executing the target applications on cloud nodes.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.13-18
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• 2022

In this paper, we proposed VW-FedAVG(Validation based Weighted FedAVG) which updates the global model by weighting according to performance verification from the models of each device participating in the training. The first method is designed to validate each local client model through validation dataset before updating the global model with a server side validation structure. The second is a client-side validation structure, which is designed in such a way that the validation data set is evenly distributed to each client and the global model is after validation. MNIST, CIFAR-10 is used, and the IID, Non-IID distribution for image classification obtained higher accuracy than previous studies.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.240-248
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• 2003

This paper analyzes mobile agent performance in network management compared to the client-server model used in the Simple Network Management Protocol (SNMP). Prototypes of an application that gathers MIB-II (Management Information Base-II) variables have been created and tested on a LAN. After acquiring implementation parameters related to network management and to the mobile agent infrastructure, simulation results have been obtained on large topologies similar in shape to the Internet. Response time results show that mobile agents perform better than SNMP when the number of managed elements ranges between two specific limits, an inferior bound and a superior one, determined by the number of messages that pass through a backbone and by the mobile agent size which grows along with MIB-II variables collected on network elements. The results also show that a significant improvement is achieved when the mobile agent returns or sends data to the management station after visiting a fixed number of nodes.

• Journal of KIISE:Software and Applications
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• v.29 no.4
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• pp.225-234
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• 2002

The developers of mobile agent systems are considering integrating the system into the web and the developers of web servers are also considering supporting mobile agents in the future. But they are not clearly suggesting the relationship between web programming which has basically client/server architecture and mobile agent programming which is based on autonomous code mobility. In this paper, firstly, we clarify the method for integrating mobile agent programming into web programming by suggesting the model for mobile agent programming on the web. Secondly, by developing APIs for Java which is widely used for both web programming and mobile agent programming, we made it possible for programmers to use them for programming mobile agent on the web. Thirdly, we show the usefulness of the proposed model by adding and testing modules for execution environment of mobile agents on W3C's Java based web server, Jigsaw.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.139-143
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• 2005

The P2P is a network environment supporting data exchange which is directly connected peers without limit of existing server-client and intervening central server for resource or offered service with each peer. JXTA is a representative of P2P system. JXTA is a typical distributed computing model that proposed by Sun Microsystems. JXTA that doesn't require centralized services or resources is adaptable in extreme changes of network organization. MANET(Mobile Ad Hoc Network) is a representative wireless network that is composed of mobile nodes without infrastructure. So MANET establishes the path for the communication of each peers and maintains the newest routing information by exchanging routing information. In this paper, we propose a technique of JXTAMAUET which implements JXTA which is the P2P network system from the wireless network which is becoming the foundation of ubiquitous computing. For the performance evaluation of the JXTAMANET, we use simulation.

• Journal of Information Technology Services
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• v.8 no.2
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• pp.157-171
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• 2009

In mobile XML environments, the efficient synchronization technique is required to maintain the consistency of replicated XML data because the same data can be replicated between so many different XML documents. In this paper, we propose a message digest based synchronization technique to maintain the consistency of replicated data between client XML documents and a server XML database in mobile XML environments. The proposed an XML data synchronization technique(XSA) has the advantage of model generality aspect and storage space aspect by using the tuple-based message digest table to detect the data conflicts. The proposed technique can be applicable to the application requiring the consistency of replicated XML data without any restrictions in the heterogeneous(between hierarchical XML documents and relational XML databases) mobile environments.

• The Journal of the Acoustical Society of Korea
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• v.22 no.4E
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• pp.176-182
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• 2003

As the needs for wireless Internet service is increasing, the needs for secure m-commerce is also increasing. Conventional security techniques are reinforced by biometric security technique. This paper utilized the voice as biometric security techniques. We developed speaker verification system for m-commerce (mobile commerce) via wireless internet and wireless application protocol (WAP). We named this system the mVprotek. We implemented the system as client-server architecture. The clients are mobile phone simulator and personal digital assistant (PDA). The verification results are obtained by integrating the mVprotek system with SK Telecom's code dimension multiple access (CDMA) system. Utilizing f-ratio weighting and virtual cohort model normalization showed much better performance than conventional background model normalization technique.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.1
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• pp.29-33
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• 2004

I propose a personalized digital library system (PDLS) based on an advanced distributed agent platform. The new platform is developed by improving the DECAF (Distributed Environment-Centered Agent Framework) which is one of the conventional distributed agent development toolkits. Also, a mobile ORB (Object Request Broker), Voyager, and a new multi agent negotiation algorithm are adopted to develop the advanced platform. The new platform is for mobile multi agents as well as the distributed environment, whereas the DECAF is for the distributed and non-mobile environment. From the results of the simulation the searched time of PDLS is lower, as the numbers of servers and agents are increased. And the user satisfaction is four times greater than the conventional client-server model. Therefore, the new platform has some optimality and higher performance in the distributed mobile environment.