• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.331-340
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• 2007

Mobile network environments are the environments where mobile devices are distributed invisible in our daily lives so that we can conventionally use mobile services at my time and place. The fact that we can work with mobile devices regardless of time and place, however, means that we are also in security threat of leaking or forging the information. In particular, without solving privacy concern, the mobile network environments which serve convenience to use, harmonized without daily lives, on the contrary, will cause a serious malfunction of establishing mobile network surveillance infrastructure. On the other hand, as the mobile devices with various sizes and figures, public key cryptography techniques requiring heavy computation are difficult to be applied to the computational constrained mobile devices. In this paper, we propose efficient PKI-based user authentication and java-based cryptography module for the privacy-preserving in mobile network environments. Proposed system is support a authentication and digital signature to minimize encrypting and decrypting operation by compounding session key and public key based on Korean standard cryptography algorithm(SEED, KCDSA, HAS160) and certificate in mobile network environment. Also, it has been found that session key distribution and user authentication is safety done on PDA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.630-637
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• 2003

This paper explains the impact of frequency error on the performance of WCDMA mobile communication systems and what brings about the frequency error between the base station and the mobile station, and then presents automatic frequency error correction method in mobile receiver. On the basis of system requirement related to frequency stability, the integration test between the base station and the mobile station was accomplished. After applying automatic frequency error correction to mobile receiver, 4 Hz of frequency error at transmitting frequency was obtained. The result met frequency error requirement of ${\pm}$0.1 ppm(about ${\pm}$200 ㎐). Performance degradation due to frequency error was measured by means of Error Vector Magnitude(EVM) at transmitter and Ec/Io at receiver, respectively and then the interface requirement between Modem control signal and RF was suggested to improve the correctness of frequency error control.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.11
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• pp.1391-1400
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• 1999

이동 통신은 대기를 전달매체로 하고 이동단말기를 사용하기 때문에 가로채기나 불법사용과 같은 공격에 취약하다. 이를 극복하기 위해, 이동 통신 환경에서 이동단말기와 기지국 사이에 안전한 통신을 제공하기 위한 많은 프로토콜들이 제안되어왔다. 그러나 이동단말기의 부족한 계산능력과 전력량 때문에 공개키를 이용한 프로토콜들은 많은 장점에도 불구하고 충분히 활용되지 못했다. 본 논문에서는 이동 통신 환경에서 기지국과 이동단말기 사이의 상호인증 및 세션키 공유 프로토콜들의 성능을 향상시킬 수 있는 기법을 제안한다. 본 논문에서 제안하는 기법은 이동단말기의 비밀 정보를 기지국에게 드러나게 하지 않으면서 많은 계산을 기지국으로 하여금 대신 수행하도록 하는 것이다. 제안된 기법은 기존의 프로토콜들을 최대 5배까지 성능을 향상시키며 해당하는 만큼 이동단말기의 전력량 소모를 감소시킬 수있다.Abstract Mobile communication is more vulnerable to security attacks such as interception and unauthorized access than fixed network communication. To overcome these problems, many protocols have been proposed to provide a secure channel between a mobile station and a base station. However, these public-key based protocols have not been fully utilized due to the poor computing power and small battery capacity of mobile stations. In this paper, we propose techniques for accelerating public-key based key establishment protocols between a mobile station and a base station. The proposed techniques enable a mobile station to borrow computing power from a base station without revealing its secret information. The proposed schemes accelerate the previous protocols up to five times and reduce the amount of power consumption of mobile stations.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.419-421
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• 2008

Recently, the mobile telecommunication industry is increasing rapidly; nevertheless it is competing severely with other mobile telecommunication industries in the world and it is projected that in the future the mobile telecommunication industry will compete more fiercely and increase more rapidly. By means of looking into characteristics of the mobile, therefore, it can be said that it can help the companies which want to survive in such a competitive society.

• The KIPS Transactions:PartB
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• v.9B no.5
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• pp.523-532
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• 2002

Recently, with the wide spread of the Internet and development of wireless network technology, it has now become possible to access web pages anytime, anywhere through devices with small display such as PDA But, since most existing web pages are optimized for desktop computers, browsing web pages on the small screen through wireless network requires more scrolling and longer loading time. In this paper, we propose a page reconstruction scheme called PageMap to make it feasible to navigate existing web pages through small screen devices even on the wireless connection. Reconstructed pages reduce the file and page size and thus eventually reduce resource requirements. We have Implemented a prototype system and performed several experiments for typical web sites. We report some of the results.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.4
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• pp.30-36
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• 2009

In this paper, we develop the next generation mobile system based on SBC(Server Based Computing). SBC is one of the popular topic and only one server system is used as multiple personal systems with a terminal, a monitor and a keyboard. The advantages of this system are easy-upgrade, low costs and convenience for each user. But it is difficult to design and manufacture the multimedia streaming system and devices control system for external devices. In this paper, we represent and develops the Mobile system based on SBC and the test performances shows that our system has good performances of multimedia system and security for internet.

• Journal of Advanced Navigation Technology
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• v.12 no.3
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• pp.239-244
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• 2008

In this paper refer to the digital multimedia mobile phone with the combination of broadcasting and the communication the unity of wire and wireless solution that can provide the UMA(Unlicensed Mobile Access) function is added. In UNC(Universal Naming Convention) in the case of CAS(Conditional Access System) is supported, the device(mobile phone) is authenticated through AP and then following the method of broadcasting signal the user can view the wanted contents as long as they want and for this matter the service charge system are proposed.

• Journal of Korea Multimedia Society
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• v.9 no.4
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• pp.401-413
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• 2006

We propose video management system based on MPEG-7 for mobile device(MVMS). Most of existing MPEG-7 applications manage MPEG-7 document based on file system in the desktop environment. To contrast them, because the MVMS manages only necessary information using embedded database system for MPEG-7 documents in mobile devices, it can use efficiently lack of the resource in mobile device environment. MVMS supports key image extraction and MPEG-7 document edition function. Moreover, this is possible search and management of multi document because of MVMS manage MPEG-7 data through embedded DB.

• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.57-63
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• 2007

Providing the sufficient energy to the mobile device is essential to process the job in distributed wireless network. To solve the restrained conditions of energy problems of mobile devices, this paper suggests the efficient method of processing the distributed job using mobility management in wireless network. Energy consumption can be analyzed using the statistical model and required energy of processing the distributed job in mobile device can be predicted using the mobility management. Therefore, this paper suggests the reliable algorithm to process distributed job through the mobile devices with regular mobility and shows the efficiency of the suggested algorithm.

• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.153-160
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• 2006

The demand of domestic mobile service has been explosively increasing. The forthcoming WCDMA, which open in 2006, is also a key technology in the mobile service market. The WCDMA service needs HSPDA phones which will be evolved to HSDPA. In the aspect of drawing up management strategy, practical researches about forecasting the demands of new mobile phones are necessary. In this paper, we provide the modified the Lotka-volterra model as a forecasting model, which is concerned with effects of phone prices and performance.