• Journal of Internet Computing and Services
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• v.7 no.3
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• pp.61-69
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• 2006

Data synchronization between data stored in mobile communication terminals and a central server is one of essential tasks for efficient mobile communication environments. Since, however, manufacturers of mobile terminals have their proprietary data synchronization mechanisms, data interoperability can hardly be achieved. Therefore, SyncML data synchronization mechanism in mobile communication environments was proposed as an open standard by OMA(Open Mobile Alliance). In this paper, a SyncML-based data synchronization gateway is designed and implemented which can process ActiveSync data also. In other words, by constructing a combined data synchronization gateway which can transform ActiveSync data into SyncML data, data interoperability between mobile terminals which use two different data synchronization mechanisms can be achieved, In addition, mobile communication experiments between ActiveSync-based terminals and a SyncML-based central server show that the data synchronization gateway constructed in this paper, works correctly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1187-1193
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• 2002

There are POP3(Post Office Progocol 3) and IMAP4(Internet Message Access Protocol 4) for E-Mail service of wire Internet For mobile e-mail service that use wireless Internet, must use exclusive use mobile e-mail server in the case of POP3 e-mail or flow e-mail conversion and because e-mail is kept in sever side with remote file server in case of IMAP4 mail that is used by Web-Mail, utilization of mobile e-mail service is difficult by mobile client who there is no IMAP4 rules. This thesis embodying e-mail extraction engine for mobile that do to design markup language converter of XML base, and use Web-Mail of recently been generalizing IMAP4 base in mobile, presented mobile e-mail service method to do so that can use Web-Mail that is based on IMAP4 as well as POP3 mail service in mobile environment.

• The KIPS Transactions:PartD
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• v.8D no.3
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• pp.221-232
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• 2001

Due to rapid advance of wireless communication technology, demand on data services in mobile environment is gradually increasing. Caching at a mobile client could reduce bandwidth consumption and query response time, and yet a mobile client must maintain cache consistency. It could be efficient for the server to broadcast a periodic cache invalidation report for cache consistency in a cell. In case that long period of disconnection prevents a mobile client from checking validity of its cache based solely on the invalidation report received, the mobile client could request the server to check cache validity. In doing so, some schemes may be more efficient than others depending on the number of available channels and the mobile clients involved. In this paper, we propose new cache consistency schemes, effects, efficient especially (1) when channel capacity is enough to deal with the mobile clients involved or (2) when that is not the case, and evaluate their performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.1-8
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• 2014

This paper proposed a method that prevents data leakage and modulation and detects an unauthorized device by using AP and mobile device. Most of existing method for detecting and preventing an unauthorized device are similar to type of Evil Twin. However, in previous studies can not resolve many security accident and have the problem to cope with effectively security accident on various network. In order to solve these problem, companies prepare security accident through the varies policy and guideline. but It is hard to prevent all security accident because it is consistently increasing everyday. This paper suggests technique of detecting and preventing an unauthorized device using Context Awareness and Mobile Device Management. Firstly, when mobile device go into internal network, server distinguish access permission and authorization of mobile device using acquiring the conetxt information of mobile device. By using this result, server applies the appropriate management technique to the mobile device for leakage and accident of internal network.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.103-106
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• 2003

A Mobile Fingerprint Identification System is implemented in this paper. The proposed system contains a server system to register fingerprints and ID data, PDA with WLAN or CDMA module and fingerprint identification module.

• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1688-1696
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• 2008

We propose a hierarchical service management method using Bloom filters for large MANETs. In this paper, a MANET is comprised of logical grid hierarchy, and each mobile node within the lowest service region multicasts the Attenuated Bloom Filter (ABF) for services itself to other nodes within the region. To advertise and discovery a service efficiently, the server node of the lowest server region sends the Summary Bloom Filter (SBF) for the ABFs to the server node of upper server region. Each upper server has the set of SBFs for lower vicinity service regions. The traffic load of the proposed method is evaluated by an analytical model, and is compared with that of two alternative advertisement solutions: complete advertisement and no advertisement. As a result, we identify that the traffic load of the proposed method is much lower than that of two alternative advertisement solutions.

• Journal of KIISE:Software and Applications
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• v.26 no.8
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• pp.974-987
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• 1999

이동 컴퓨팅 환경에서 자주 접근하는 데이터에 대한 캐싱은 무선 채널의 좁은 대역폭에서 경쟁을 줄일 수 있는 유용한 기술이다. 그러나, 트랜잭션 캐시 일관성을 지원하는 전통적인 클라이언트/서버 전략은 클라이언트와 서버간에 많은 양의 통신을 필요로 하기 때문에 이동 클라이언트/서버 컴퓨팅 환경에서는 적절하지 않다. 본 논문에서는 브로드캐스트-기반 캐시 무효화 정책을 사용하면서 트랜잭션 캐시 일관성을 지원하는 OCC-UTS (Optimistic Concurrency Control with Update TimeStamp) 프로토콜을 제안한다. 접근한 데이터에 대한 일관성 검사 및 완료 프로토콜은 캐시 무효화 과정의 내부 과정으로 완전 분산 형태로 효율적으로 구현되며, 일관성 체크의 대부분이 이동 클라이언트에서 수행된다. 또한, 분석 모델에 기반한 성능 비교를 통해, 본 논문에서 제안하는 OCC-UTS 프로토콜이 다른 경쟁 프로토콜보다 높은 트랜잭션 처리율을 얻으며, 데이터 항목을 자주 접근하면 할수록 지역 캐시를 사용하는 OCC-UTS 프로토콜이 더 효율적임을 보인다. 이동 클라이언트의 접속 단절에 대해서는 무효화 브로드캐스트 윈도우를 크게 하여 접속 단절에 적절히 대처할 수 있다.Abstract In a mobile computing environment, caching of frequently accessed data has been shown to be a useful technique for reducing contention on the narrow bandwidth of the wireless channels. However, the traditional client/server strategies for supporting transactional cache consistency that require extensive communications between a client and a server are not appropriate in a mobile client/server computing environment. In this paper, we propose a new protocol, called OCC-UTS (Optimisitic Concurrency Control with Update TimeStamp), to support transactional cache consistency in a mobile client/server computing environment by utilizing the broadcast-based solutions for the problem of invalidating caches. The consistency check on accessed data and the commitment protocol are implemented in a truly distributed fashion as an integral part of cache invalidation process, with most burden of consistency check being downloaded to mobile clients. Also, our experiments based on an analytical model substantiate the basic idea and study the performance characteristics. Experimental results show that OCC-UTS protocol without local cache outperforms other competitor protocol, and the more frequent a mobile client accesses data items the more efficient OCC-UTS protocol with local cache is. With respect to disconnection, the tolerance to disconnection is improved if the invalidation broadcast window size is extended.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.483-488
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• 2004

Comparison of prices and specifications is a very important informations for the decision of buying selected goods. It is hard to get informations of comparison of prices and specifications at the spot on off-line shopping. In this paper, we propose a system that provides optimized information of goods by PDA mobile phones and other mobile devices. The proposed system consists of a server that include a search robot and clients that can read barcode. When a client send the barcode information scanned by a camera attached his/her mobile device, the server sends the information of the goods to the client.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.7-18
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• 2016

Several authentication methods have been developed to make use of tokens in the mobile networks and smart payment systems. Token used in smart payment system is genearated in place of Primary Account Number. The use of token in each payment transaction is advantageous because the token authentication prevents enemy from intercepting credit card number over the network. Existing token authentication methods work together with the cryptogram, which is computed using the shared key that is provisioned by the token service provider. Long lifetime and repeated use of shared key cause potential brawback related to its vulnerability against the brute-force attack. This paper proposes a per-transaction shared key mechanism, where the per-transaction key is agreed between the mobile device and token service provider for each smart payment transaction. From server viewpoint, per-transaction key list is easy to handle because the per-transaction key has short lifetime below a couple of seconds and the server does not need to maintain the state for the mobile device. We analyze the optimum size of the per-transaction shared key which satisfy the requirements for transaction latency and security strength for secure payment transactions.

• The Journal of Society for e-Business Studies
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• v.12 no.2
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• pp.1-16
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• 2007

Recently the computing environment has been moved to open architectures that include Web technologies. Web Service is one of import component of the new paradigm. This paper presents a design and implementation of GIS Web Service for mobile devices. As many mobile devices are equipped with GPS (Global Positioning System), it is required to handle the position information more effectively. We have extended the proxy program in the client device to actively send the context information to the server. Based on the context information the server determines the optimal service mode to a particular client. A working example of location?based GIS Web Service is also presented. By using Web Service standards and XML messages we can achieve the maximal interoperability for heterogeneous mobile devices.