• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.53-58
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• 2007

The Satellite Mobile Communication System holds several advantages, such as wide coverage that guarantees the communication in a huge area. It is suitable in the ocean and forest and especially in emergency situation. However, the licensed frequency is not always occupied within all coverage and all the time. The actual utilization rate is relatively low compared to other wireless communications such as cellular systems. There are a large amount of white spaces in its coverage. Therefore, it is necessary to consider introducing additional services such as data communication, in order to increase the spectrum utilization as well as the revenue of the Satellite service provider. In this paper, we first analyze the possibility to implement new services in the licensed band of satellite mobile phone by its provider. Then we address the most significant issue for the implementation of current service, which is how to accurately detect the satellite mobile terminals. Finally, we suggest two new possible solutions namely, eigenvalue detection based methods to find out the existence of transmitted signal from the satellite mobile terminals.

• ETRI Journal
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• v.35 no.2
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.183-192
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• 2015

This paper proposes Personal Information Auto Detection(PIAD) System to prevent leakage of Personal informations in document and image files that can be used by mobile service provider. The proposed system is to automatically detect the images and documents that contain personal informations and shows the result to the user. The PIAD is divided into the selection step for fast and accurate retrieval images and analysis which is composed of SURF, erosion and dilation, FindContours algorithm. The result of proposed PIAD system showed more than 98% accuracy by selection and analysis steps, 267 images detection of 272 images.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1714-1725
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• 2003

In this paper we propose reliable billing schemes between users and contents providers where a user is provided value­added service for a paid contents using mobile terminals. Our schemes support various types of services such as short messages, bell sounds, images or music data transmissions, and games in mobile communication environments. Using hash chain method, we also reduced the computational overhead of mobile terminals and the volume of data transmitted between the user and the content provider. Content providers can save memory space because they don't need to store each user's usage evidence but still can charge.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.53-57
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• 2013

The quality of service for the voice and data communication is one of the most important elements in the mobile cellular networks. This quality has the time varying characteristics depending on the wireless network environments. In order to guarantee the quality of service at the predefined level, the mobile service provider needs to collect all the information about the level of quality served by the local base stations. In the conventional method the information on the service quality is measured and collected by the moving vehicle adopting the global positioning device. However this method requires relatively high cost and does not cover all the service areas. In this paper a new method is proposed utilizing a measurement node with local area communication transceiver and the mobile user equipment. In the proposed method the node communicates with the user equipment periodically to monitor the information on the service quality. The resulting information is reported to the measurement server in the mobile network. This method could be applied to either the circuit or the packet based networks. It also has an advantage in terms of the cost efficiency compared to the conventional method considering the required the equipment and the human resources.

• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.167-179
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• 2005

In hierarchical Mobile IPv4 Networks the highest FA(Foreign Agent) may experience serious congestion and delay since the highest FA plays a role of CoA(Care of Address) for all mobile nodes in the domain, In this paper, we propose mechanism called 'HRFA(Hierarchical Root Foreign Agent)', which distributes the load imposed on the highest FA. In the proposed HRFA scheme, multiple HRFAs are selected to provide the similar service that is provided by the highest FA. According to which entity determines HRFAs, HRFA scheme is categorized into 'Active' and 'Passive' approaches. HRFA scheme is further categorized into 'All MN(Mobile Node)s' and 'New MNs' approaches, depending on which mobile nodes are assigned to a newly elected HRFA. Through a course of simulations, we investigate the performance of 4 possible combinations of HRFA schemes. We also compare the performance of the proposed HRFA schemes with the LMSP(Local Multicast Service Provider) scheme, which is a scheme to distribute the load of FA for multicast service in hierarchical wireless network domain. The simulation results show that the Passive & New MN approach performs best with respect to both the overhead and the load balancing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2178-2184
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• 2015

With the development of wireless network technologies, mobile users may use various networks easily and expect more advanced services. On the other hand, it may bring on some problems with network resource management that should lead the service provider to improve the current service quality and manage the network resource efficiently. This paper proposes the optimized radio resource management (RRM) scheme that integrates the Grey Relational Analysis (GRA) and game theory. The first applies the GRA to determine the Grey Relation Coefficient (GRC) factors that represent the network preference, and the network provider then selects the requested service that provide maximum payoff through Nash Equilibrium. Six requested services that have one application service among four different types of service classes were considered and the game was played repeatedly. In WiMAX, WLAN 1 and WLAN 2 game, the maximum payoff of each players was 93, 90.6 and 92.8 respectively. The experimental results show that every requested service can be selected by the network provider. Consequently, the proposed radio resource management mechanism is more effective in heterogeneous wireless networks.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.25-33
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• 2008

Video telephony is a representative service in 3G mobile network. And there have been efforts to improve quality of video telephony service in different fields. In Korea, the leading mobile service provider SKTelecom and KTF service the WCDMA network as 3G mobile network. Now, more than a million people is using the network. In this paper, we study about video telephony over WCDMA network. and propose error minimizing algorithm using cross-layer adaptation between physical layer and video codec. We simulated 3G-324M protocol with MPEG-4 video codec, and simulation results show suggested algorithm improve packet transmission rate for improving quality of video telephony service.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.592-595
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• 2004

Recently the numbers of patent about the technology for mobile payment with Ie or bluetooth-chip are being increased more and more. The reasons of patent increment for mobile payment are advancement of wireless internet technology and rising of customer's request for it. The customer wants to be able to pay for purchase, tax and aid with own mobile phone. So every mobile service provider applies for patents about that competitively. And in the near future the biometrics is generalized in the mobile payment system. Especially the payment service of iris recognition is significant technique in this area for the future prospect. The biometrics of iris is an accurate authentication method because it has about 250 distinguish parameters to the finger print's 30. The biometrics of iris can recognize and identify a person for 2 seconds. But the image of iris is changed by transformation of body in the life. And the existing iris authentication system has problem that can be miss-recognized. In this paper, we propose the new method that reduces miss-recognizing rate with Renewable Iris Authentication Algorithm(RIAA) in mobile system.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.3
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• pp.125-132
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• 2005

Wireless access always has to include the authentication of communication partners and the encryption of communication data in order to use secure M-Commerce services. However, wireless systems have limitations compared with the wired systems, so we need an efficient authentication and key exchange protocol considering these limitations. In this paper, we propose an efficient authentication and key exchange protocol for M-Commerce users using elliptic curve crypto systems. The proposed protocol reduces the computational load of mobile users because the wireless service provider accomplishes some parts of computations instead of the mobile user, and it uses the password-based authentication in wireless links. Also, it guarantees the anonymity of the mobile user not to reveal directly the real identity of the user to the M-Commerce host, and preserves the confidentiality of communication data between the M-Commerce host and the user not to know the contents of communication between them to others including the wireless service provider.