• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.55-59
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• 2004

Recently the wireless-internet has been spreading extensively. People are spending a large part of their time gaining access to information using a mobile device. However. limited process speed. low bandwidth, the low battery capacity of mobile devices and a high rate of wireless network errors brings out many overheads during service time with server for service. In this paper, we suggest an autonomous service delivery system. which provides mobile agent capability to users that can not maintain a connection. We have developed the system based on java mobile agent technology. Using this system, we can provide more effective services to users when the user is sending requirements of service through a mobile device that has limited resources and can manage the contact server dynamically when new services are added.

• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.19-26
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• 1998

Mobile database system address information processing based on database system in mobile computing environment. In the mobile database system, when a mobile transaction host enter a other radio coverage area called a cell while processing a transaction, it have to alter the communication network address to new database server. This is called transactional service handoff. This paper propose a transaction processing scheme for providing the proper function of this transactional service handoffs in mobile database system. This scheme apply coordinator migration mechanism which perform the transaction in new database server when posed to be the transaction service handoff. Fially, the proposed scheme will improve system performance by minimizing the tansmission of message for processing the transactions in mobile database system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.107-114
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• 2003

In this paper, we propose an efficient mutual authentication and key distribution protocol for cdma2000 packet data service which uses Mobile U access method with DIAMETER AAA(Authentication, Authorization and Accounting) infrastructure. The proposed scheme provides an efficient mutual authentication between MN(Mobile Node) and AAAH(home AAA server), and a secure session-key distribution among Mobile If entities. The proposed protocol improves the efficiency of DIAMETER AAA and satisfies the security requirements for authentication and key distribution protocol. Also, the key distributed by the proposed scheme can be used to generate keys for packet data security over 1xEV-DO wireless interface, in order to avoid a session hijacking attack for 1xEV-DO packet data service.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.97-107
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• 2008

This paper proposes a mutual authentication scheme for mobile router in MANEMO. The NEMO used AAA server in order to authenticate mobile router in nested mobile network. So, this scheme has some problem that increases authentication message overhead and authentication time. The proposed scheme uses temporary certificate that signed by an access router's private key. The temporary certificate authenticates a mobile router when the mobile router entered a MANET domain. The proposed scheme reduces authentication message overhead and authentication time than the scheme to use AAA server when authenticating the mobile router.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.843-850
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• 2004

As mobile devices prevail, requests for various services using mobile devices have increased. Requests for application services that require large data space such as multimedia, game and database [1] specifically have greatly increased. However, mobile appliances have difficulty in applying various services like a wire environment, because the storage capacity of one is not enough. Therefore, research (5) which provides remote storage service for mobile appliances using iSCSI is being conducted to overcome storage space limitations in mobile appliances. But, when iSCSI is applied to mobile appliances, iSCSI I/O performance drops rapidly if a iSCSI client moves from the server to a far away position. In the case of write operation, $28\%$ reduction of I/O performance occurred when the latency of network is 64ms. This is because the iSCSI has a structural quality that is very .sensitive to delay time. In this paper, we will introduce an intermediate target server and localize iSCSI target to improve the shortcomings of iSCSI performance dropping sharply as latency increases when mobile appliances recede from a storage server.

• Journal of Korea Spatial Information System Society
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• v.6 no.2 s.12
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• pp.39-49
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• 2004

An increasing number of distributed applications will be achieved with mobile technology. These applications face temporary loss of network connectivity when they move. They need to discover other hosts in an ad-hoc manner, and they are likely to have scarce resources including CPU speed, memory and battery power. Software engineers building mobile applications need to use a suitable middleware that resolves these problems and offers appropriate support for developing mobile applications. In this paper, we describe the meta-server building for middleware that addresses reflective context awareness and present usability with demonstration. Metadata is consist of user configuration, device configuration, user context, device context and dynamic image metadata. When middleware send a saving or retrieval request to meta-server, it returns messages to middleware after the verification of the request. This meta-server has the application for multimedia stream services with context awareness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.789-798
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• 2016

In this paper, we propose a cache algorithm based on user's context for enterprise/urban smallcell environments. The smallcell caching method is to store mobile users' data traffic at a storage which is equipped in smallcell base station and it has an effect of reducing core networks traffic volume. In our algorithm, contrary to existing smallcell cache algorithms, the cache storage is equipped in a edge server by using a concept of the Mobile Edge Computing. In order to reflect user's characteristics, the edge server classifies users into several groups based on user's context. Also the edge server changes the storage size and the cache replacement frequency of each group to improve the cache efficiency. As the result of performance evaluation, the proposed algorithm can improve the cache hit ratio by about 11% and cache efficiency by about 5.5% compared to the existing cache algorithm.

• Journal of Korea Spatial Information System Society
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• v.11 no.4
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• pp.56-64
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• 2009

As the Internet has been improved to Web 2.0, it introduces new approaches including Rich Internet Application (RIA) technology such as Flash, AJAX, Silverlight, etc. The RIA which is platform independent technology allows applications to provide rich client-side interfaces, and allows the browser to interact with users without communication to server. In this paper, we propose a method of spatial data service based on RIA technology. Internet map service using spatial data generally requires rich client-side interfaces and various interactions. These features can be provided by the RIA. The proposed method uses Flash developed by Macromedia as RIA technology. It can be applicable on any platform including mobile environment. The spatial data server makes Flash file known as SWF (Shock Wave File) with manipulation code for map and spatial data that is requested by user, and send it to the web browser. Once the web browser receives a SWF, client SWF manipulates user interactions, such as zooming and panning, without communication with server. Experiments that execute the application on various web browsers including mobile web browser and measure time of map interaction are carried out to compare with traditional bitmap based WMS (Web Map Service). As a result of experiments, we have confirmed improvement of interactivity and performance with RIA approach.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.195-202
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• 2020

The control system for the efficiency of resource utilization in sensor network environment based on object detection and environmental sensor requires active control function which based on sensor data acquisition and transmission functions and server's data analysis. Using active rule-based mobile agent middleware, this paper proposes a new distributed control framework that reduces the load of central sensor data server in sensor network environment by implementing remote data sensing and Zigbee-based communication with server and data analysis method of server. In addition, we implemented a power-saving system prototype using active rule-based distributed control methods that applied consumer's demand and environmental variables, and verified the validity of the proposed system through experiments and evaluations in the mobile agent middleware environment. The proposed system is a system framework that can efficiently autonomously control distributed objects in the sensor network environment, and it can be applied effectively to the development of demand response service based on optimal power control for the smart power system in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2418-2423
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• 2012

A smart phone which is one of the new IT technologies can be viable on various enterprise applications since it provides easily information and services. Especially, a smart phone can request queries to a server which finds massive data for decision making and receive the results of the queries from the server. However, a smart phone has a drawback that its battery is consumed easily due to the 4G communication. In this paper, we propose mobile views in order to reduce the easy consumption of a battery on mobile client-server environment. The proposed mobile view scheme reduces the number of communication which is leading to power consumption using materialized views for processing queries. We also classify the methods to control the consistency of the mobile view as the sources of the view are changed and present the cost of each method based on the cost model of battery consumption.