• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.7
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• pp.1329-1345
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• 2011

After the 9.11 terror attack, lawful Interception (LI) has emerged as an important tool for anti-terrorist activity. Law enforcement agents and administrative government bodies effectively monitor suspicious target users of permanent IP-based network devices by LI in Packet Data Networks (PDNs). However, it is difficult to perform LI in monitoring migrating users from a location to another, who change their IPs due to the proliferation of portable Internet devices enabling 3G IP Multimedia Subsystems (IMS). The existing, manual handover technique in 3G IMS makes it even more difficult to continue the LI activities due to time-lag reissuance of LI authority warrants when the target users move to a new LI jurisdiction via a roaming service. Our proposed model is a seamless LI handover mechanism in 3G IMS to support mobility detection of the target users. The LI warrants are transferred to the new LI agent automatically with the target users when they move to a new LI jurisdiction. Thus, time-lag human intervention of reissuance of the LI warrants is removed and enables the LI authorities to continue monitoring. In the simulation of our proposed mechanism, the quality of lawful interception achieves a mean score of over 97.5% out of the possible 100% maximum score, whereas the quality of the existing mechanism has a mean score of 22.725%.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.391-398
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• 2008

To provide IPTV service over mobile networks, the mechanism that reduce packet loss and interrupt of multimedia service during the handover should be supported. Especially, buffering based mechanism is preferable for supporting IPTV services in the way of preserving streaming service using stored data and recovering non-received data after handover. But previous research doesn't consider the buffer allocation for applying various environments which can change handover time or end to end delay of relay node. This paper propose DBAHAJ mechanism that optimize buffer size of mobile nodes and relay node for supporting seamless IPTV service over mobile environments. Mobile node determines buffer size by checking handover time and maximum difference of sequence to keep playing video data. And multicast agent recovers packet loss during the handover by sending buffered data. By these two procedure, node supports seamless IPTV service on mobile networks. We confirm performance of this mechanism on NS-2 simulator.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.601-606
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• 2015

Recently wireless data services have widely spread on various multimedia devices such as smart phones and tablets. Existing wired data services have been replaced by wireless data services using mobile devices. Especially domestic mobile devices supporting both Wireless-Fidelity (Wi-Fi) and long term evolution (LTE) services have increased steadily. While Wi-Fi network is provided free of charge, LTE network is offered to pay for. Therefore, mobile devices provide smart network switch to support both preferred Wi-Fi and LTE networks. However, such handover and roaming between Wi-Fi and LTE networks can cause data connection stop in spite of charged data services. This paper has proposed the method to overcome data connection stop for guaranteeing seamless data service during handover and roaming procedures between networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.153-160
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• 2009

A hierarchical network between Mobile-WiMAX and WLAN systems is to make it possible to utilize wireless internet services including time sensitive applications such as VoIP, VOD, visual telephony etc. During the process of vertical handoff decision from Mobile-WiMAX to WLAN hotspot, vertical handoff delay causes user dissatisfaction because it doesn't provide the seamless wireless internet service. We make use of type of service (ToS) parameters in IEEE 802.16e specification as the criterion parameter of vertical handoff decision process in hierarchical Mobile-WiMAX/WLAN networks. In this paper, we propose the process of vertical handoff decision for seamless wireless internet service which is sensitive to time delay. If type of service is time sensitive application, the decision of vertical handoff is withdrawn until the service is terminated. In focus on user satisfaction, if the proposed traffic management strategy in hierarchical Mobile-WiMAX/WLAN networks is used, user will utilize seamless wireless internet services including time sensitive applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.195-202
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• 2005

The third generation cellular system requires the seamless macro/micro mobility support. Mobile IP provides a simple and scalable macro mobility solution but lacks the support for fast handoff control in micro-domain. However, A lot of micro-mobility protocols have been proposed to complement the Mobile IP capability by providing the fast, seamless, and local handoff control. Cellular If also provides the seamless mobility support in limited geographical area. But semi-soft handoff mechanism of Cellular IP produces the packet loss and the duplication problem due to the difference of propagation delay between the new path and the old path. In this paper, we present an efficient handoff mechanism in micro-domain. The proposed handoff mechanism uses the SCD (Suitable Cross Delay) in order to minimize the packet loss and the duplication problem during the handoff. Also, the proposed mechanism is verified by the performance evaluation through the NS-2 Simulation.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.94-102
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• 2007

Today, packet services for wireless internet is provided by WiBro WLAN 3G, but it is hard to be satisfied seamless connection in each of networks and wide-area service will increase the number of BS(base station) because WiBro and WLAN has been coverage smaller than 3G. that is, communicate which can use continuous and seamless data service is available when user is moving. Therefore, service provider need to integrate network for reducing management expenses. In this paper, we propose advanced handoff algorithm which is considered by 'user demand bandwidth', 'MN(Mobile Node) movement speed' and 'MN service area' and show that simulating result is superior to 'bandwidth allocation', 'QoS(Quality of Service) rate' and 'handoff failure rate'

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.546-557
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• 2016

Tooth carving practice is required for novice learners in dentistry to understand dental morphology and acquire clinically underlying skills. Tooth carving practice is more effective when sequential models can be observed. The purpose of this study is to suggest a tooth carving practice model and to develop a mobile practice supporting tool based on tutorial providing 3D modeling information about steps of tooth carving. As a result, tooth carving practice model consists of the class activity including tooth information lecture and practice and mobile seamless learning connecting learners' practice and regular learning with the mobile tutorial tool. The mobile tutorial tool is implemented with tooth morphology dictionary, tooth carving practice/training tutorial, and 3D tooth modeling. The experts' evaluation on the developed contents shows that the content and function are valid(content validity: 5.0, interface validity: 4.53). Therefore, the mobile tutorial tool is suitable for supporting mobile seamless learning for tooth carving practice. Further researches are expected to be conducted to develop instructional models utilizing ICT and mobile contents in dentistry.

• Journal of Information Technology Services
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• v.19 no.5
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• pp.1-14
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• 2020

Mankind has been attempting to live a happy and safe family life in a residential space. Due to the advent of the mobile phone in the 1990s and the smart phone in the 2000s, when the information and communication age came, human life has been innovatively changed. The revolution of human civilization led to the Neolithic Revolution and the Iron Age, followed by a smart phone revolutionizing human life, and the revolution faces with the era of info-communication, smart phones became a daily life and the fourth industrial revolution. The fourth industrial revolution is an era of info-communication technology (ICT), creating a new paradigm across human life through technological developments such as artificial intelligence (AI), IoT, big data, mobile, and cloud. The smart home is actively researched in a direction to support the overall human life as a representative future residential culture paradigm. However, the study considering the needs according to the lifestyle, functional characteristics of each living space and human lifestyle of the Phono Sapiens era where smart phones live like daily life was relatively insufficient. In addition, research on smart home service design should be considered from the apartment residential space planning stage. Therefore, this study has significance in suggesting the direction of research on human-centered smart home service design considering the characteristics of each living space and resident's life-style in the smart phone era.

• Journal of Intelligence and Information Systems
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• v.12 no.3
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• pp.1-13
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• 2006

Ubiquitous computing is a study area explained in a myriad of contexts and technological terms. Payment, however, refers in nature to an act of money transfer from one entity to another, and it is obvious that a payment method will be valued as long as the transaction can be completed with safety no matter what technology was used. The key to U-payment is convenience and security in the transfer of financial information. The purpose of this paper is to find a desirable U-payment scheme by looking at the characteristics of seamlessness under the ubiquitous environments, strong personal device, and peer-based information transactions. We also propose U-SDT Protocol integrating technologies such as Radio Frequency Identification (RFID), Bluetooth, Personal Payment Device, Account Managing Application and Transaction ID as a way to make transactions between users seamless and secure better privacy protection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1185-1192
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WPAN protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless WPAN protocol, a Grid-based WPAN networking technology is proposed and analyzed. The proposed Grid-based WPAN networking technology supports multi-path and fast path-setup functions for N-screen communications. The simulation results demonstrate that the proposed Grid-based WPAN networking technology outperforms the IEEE 802.15.4 based network in terms of N-screen transmission delay.