• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.395-403
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• 2011

Various studies were performed for providing the latest spatio-temporal information in mobile GIS Environments. The two-way synchronization scheme collects updated spatio-temporal data in the field and synchronizes with a server by using the wireless network. However, the other mobile terminals have to perform periodically synchronizes with a server. In this paper, we propose the update propagation scheme about spatio-temporal data collected from the mobile terminal. The update propagation scheme does considering various factors where an influence is in the update propagation. Therefore, it provides various update propagation policies according to each factors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.797-801
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• 2008

This paper describes technical method about remote control and monitoring of local system by use personal mobile device in anytime and anywhere. Therefore, the user don't need to stay in operation room of local system. The PC server environment for the mobile connection are constructed with Apache web server, PHP and MySQL ODBC. The mobile internet homepage for the remote mobile connection is designed by Anybuilder software and mobile simulator, Openwave SDK 6.2 is used for the development. The mobile internet program can be applicate to all of domestic communication companies LGT, SKT and KTF. We use KTF mobile contains WAP browser for the test. We used NI Labview software to control and monitoring of local system. The local system, which will be controlled remotely have constructed with analog/digital signal acquisition device, signal control board and their software. By experiments, we confirmed remote control by mobile device are possible.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.1_2
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• pp.80-89
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• 2001

The development in the mobile computing systems have arisen new and previously unforeseen problems, such as problems in information management of mobile host, disconnection of mobile host and low bandwidths of wireless communications. Especially, location information management strategy of mobile host results in an increased overhead in mobile computing systems. Due to the mobility of the mobiles host, the changes in the mobile host's address depends on the mobile host's location, and is maintained by mapping physical address on virtual address, Since previously suggested several strategies for mapping method between physical address and virtual address did not tackle the increase of mobile host and distribution of location information, it was not able to support the scalability in mobile computing systems. Thus, to distribute the location inrormation, we propose an advanced n-depth LiST (Location information Search Tree) and the parallel location search and update strategy based on the advanced n-depth LiST. The advanced n-depth LiST is logically a hierarchical structure that clusters the location information server by ring structure and reduces the location information search and update cost by parallel seatch and updated method. The experiment shows that even though the distance of two MHs that communicate with each other is large, due to the strnctural distribution of location information, advanced n-depth LiST results in good performance. Moreover, despite the reduction in the location information search cost, there was no increase in the location information update cost.

• The KIPS Transactions:PartD
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• v.13D no.6 s.109
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• pp.847-856
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• 2006

In this paper, we suggested a mobile collaboration framework for supporting mobile services among mobile devices, and designed and implemented on this environment. The suggested framework has three elements; groups of sensors and mobile devices(Fixed and Moving-typed PDAs) and a home server. We designed interfaces for interactions with each other in collaboration environment with three elements described above. The information collected by sensors can be share and exchanged by mobile devices or a home server in accordance with Push and Pull methods. This framework is based on the distributed object group framework(DOGF) we implemented before. Therefore the DOGF provides functions of object group management, storing information and security services to our mobile collaboration framework via application interfaces defined. The information collected by sensors is arranged according to user's security 'demands. And user profile information is used for checking authority of each service object. Each component for executing functions of mobile devices and a home server is implemented by TMO scheme. And we used the TMOSM for interactions between distributed components. Finally, we showed via GUI the executablity of a given healthcare application scenario on our mobile collaboration framework.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.21-30
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• 2005

In mobile computing environments, a mobile host caches the data to use the narrow bandwidth efficiently and improve the response time. A server periodically broadcasts the update data for maintaining the cache consistency of a mobile host. However, a method for maintaining cache consistency using periodic invalidation report has a problem that defers the commit decision of a mobile transaction to guarantee its serializable execution. In this paper, we propose CCM-AD method that guarantees the serializable execution of a mobile transaction even in the case that it is executed using cached data. As CCM-AD method guarantees the serializable execution of mobile transactions by using the intersection between the data broadcast to mobile host and the data updated at server. Then the CCM-AD method can reduce the delay of commitment decision of a mobile transaction. Also our method can reduce the size of invalidation report.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3916-3936
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• 2014

Smartphone applications like games, image processing, e-commerce and social networking are gaining exponential growth, with the ubiquity of cellular services. This demands increased computational power and storage from mobile devices with a sufficiently high bandwidth for mobile internet service. But mobile nodes are highly constrained in the processing and storage, along with the battery power, which further restrains their dependability. Adopting the unlimited storage and computing power offered by cloud servers, it is possible to overcome and turn these issues into a favorable opportunity for the growth of mobile cloud computing. As the mobile internet data traffic is predicted to grow at the rate of around 65 percent yearly, even advanced services like 3G and 4G for mobile communication will fail to accommodate such exponential growth of data. On the other hand, developers extend popular applications with high end graphics leading to smart phones, manufactured with multicore processors and graphics processing units making them unaffordable. Therefore, to address the need of resource constrained mobile nodes and bandwidth constrained cellular networks, the computations can be migrated to resourceful servers connected to cloud. The server now acts as a bridge that should enable the participating mobile nodes to offload their computations through Wi-Fi directly to the virtualized server. Our proposed model enables an on-demand service offloading with a decision support system that identifies the capabilities of the client's hardware and software resources in judging the requirements for offloading. Further, the node's location, context and security capabilities are estimated to facilitate adaptive migration.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.689-697
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• 2004

Rapid advances in mobile computing and the availability of wireless communications will soon provide mobile users with the ability to access data regardless of the location of the user or of the data. SRA(Static Replica Allocation) that is traditional scheme has been used for the replication method on the server. This replicates the data on the replica server after a moving host has been transferred to the cell. This strategy is simple and can easily relocate data. However, if a mobile user does not exist in the cell, the replicated data can be deleted in order to maintain data consistency. In addition to, if the mobile host leaves from replicated cell, it is difficult to access data in terms of replication route. Therefore, this paper proposes a new method of relocation based on data consistency strategy called USRAC(User Selection Replica Allocation based on Consistency) and also analyzes access cost according to the moving rate of mobile users, according to the access rate of mobile hosts, and according to the number of cells of mobile users and mobile hosts.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1873-1879
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• 2007

As the mobile terminal which uses P2P service increases and it comes to be applied to many fields, mobile agent technology has been applied to P2P and its innovative services has been offered to various fields. However, free mobility of mobile agent technology works like worm, the problem which is contaminated by malicious attacker's attack quickly has appeared and fundamental solution has not been developed yet. This paper proposes STAS (Security Tracking and Auditing Server) system which can offer verification for security of mobile agent in structured P2P environments. Mobile Agent will send data value to STAS via peer so that STAS can verify secure audit and integrity and Mobile agent initiator will obtain the final value of the data from STAS. It can minimize overload of mobile terminal which is occurred by verification of mobile agent and its accomplishment.

• Journal of the Korea Society for Simulation
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• v.12 no.2
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• pp.55-62
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• 2003

The explosive Increase of wireless networks and the advancement of mobile devices lead to the expansion of mobile environment. In accordance with the development of mobile environment, the need to use mobile database is increased sharply, and also it accompanies the related problems. The current mobile database system is based on the centralized method from which a synchronized server manages multiple mobile database management system to synchronize. From this mobile system architecture, several kinds of problems can be detected such as the management of synchronization issues between mobile databases and the transaction management issues. Furthermore, the current mobile database management system does not consider any solution on the fault tolerance. To solve those problems, this paper proposes the mobile agent-based mobile database management system. The proposed system provide high confidence and efficiency by enhancing the network efficiency and fault tolerance through the mobile grouping.