• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.461-470
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• 2006

Recently mobile Stream Control Transmission Protocol (mSCTP) has been proposed as a transport layer approach for supporting mobility. When a mobile terminal (MT) is not located in the home network. a terminal that wishes to communicate with the MT is not able to establish mSCTP association to the MT, since mSCTP does not include the location management mechanism. In order to solve this problem. an interworking approach using the Session Initiation Protocol (SIP) INVITE method has been proposed. However, this approach has shown subsequent delay in acquiring the current location information of the MT when initiating mSCTP association establishment. In this paper, we propose new SIP methods and an approach that minimizes the address acquisition delay (AAD) by utilizing those SIP methods. Mathematical analysis and simulation results show that the proposed approach is more efficient than the previous approach in terms of AAD in all kinds of SIP environments.

• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.481-491
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• 2008

As the T-DMB (Terrestrial Digital Multimedia Broadcasting) has been actively launched, all the service providers are focusing on finding a new business model using a variety of data services as well as video service. The middleware technology for data broadcasting service, which was presented due to such necessity, known as DMB MATE (Mobile Application Terminal Environment), provides a running environment of the applications and APIs so that the various data applications can support high-level functionalities for the interactive data service. In this paper, in order to effectively provide the data service under restricted channel environment of T-DMB, we introduce a service technology and an interactive data broadcasting system using the DMB MATE, specifically proposing a design method of T-DMB MATE receiver capable of the presented DMB MATE service. Finally, the performance of developed system is confirmed through the T-DMB data broadcasting experiment under a variety of conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2210-2216
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• 2007

In this paper, triple-band plastic chip antennas for mobile terminal are investigated. Plastic chip antenna is composed of Foamex material with circle of PVC(Polyvilyl chloride). For its electric characteristics, the dielectric constant is 1.9, the insulation intensity is 112KV/cm. Plastic chip antennas are don't tend to break easily against to external shock, have more gain and efficiency than ceramic chip antennas. Triple-band plastic chip antennas of four type are implemented and experimented. From the experiments results, the antenna resonate at the triple-band, the gain of the antennas has about above -2dB, the pattern is ommidirectional the same as the conventional antennas. So, the antennas realized with Foamex material will be application for mobile phone antenna operated at the triple band which is cellular band and Korea-PCS band and ISM band or the antenna for other wireless communication system.

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.1
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• pp.1-7
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• 2010

Recently, interest in u-learning to pursue effective learning by using ubiquitous environment in teaching and learning activities. In u-learning environment, learners should be able to push necessary information at the right time and the right place. Also calm technology oriented to, and this means that it can recognize learners' terminal information and to provide adaptive interface. In u-learning environment, main learning terminals would be mobile terminals which support mobility. However, learning in the existing PC environment should not be excluded. Thus, by providing adaptive interface according to various learners' terminal in LMS for u-learning, learners are able to learn through consistent and natural learning interface with any computer or any network at any place and at any time. The purpose of this study is to propose the interface adaptation based on terminal information focusing on the layout transformation process in the development environment.

• Design & Manufacturing
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• v.10 no.1
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• pp.36-40
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• 2016

Connectors transmit electric signals to different parts in compact mobile display products. As products that apply this have become lightweight and smaller in size, there are growing demands for smaller and more integrated connectors, which are internal parts of the products. As a measure to address these demands, there is the planar array connector that minimizes the part by arranging the single-direction BTB connectors to two directions. As connectors become smaller in size and more highly integrated, maintaining intensity to prevent defects during impact and maintaining adhesive force to smoothly transmit electric signals are growing in importance. Thus, in order to identify the impact of concave shaping on improving adhesive power in connector terminal pins as a method to increase the connecting power of planar array connector terminal pins, this study predicted and examined the concave shaping method, number of concave shapes, and the adhesive power according to the size of the concave shape through CAE. For concave shaping, the model that added concave shaping towards the lower part of the connector terminal pin and added spokes for the area pressed down by the concave shaping was 0.74 N, showing increased adhesive force compared to existing models. Furthermore, when applying two concave shaping, rather than just one, there was a tendency for adhesive force to increase. In the case of adhesive power trends according to the size of the concave shaping, adhesive power increased and the width of the concave shape decreased, and the biggest adhesive force trends were shown when the concave shaping depth was 0.01mm.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.682-686
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• 2006

There have been increasing interests in 3D mobile content service with emergence of a terminal equipping with a mobile 3D engine and growth of mobile content market. Mobile 3D Avatar is the most effective product displaying the character of a personalized mobile device user. However, previous studies on the method of expressing 3D Avatar have been mainly focused on natural and realistic expressions according to the change in facial expressions and lip shape of a character in PC based virtual environments. In this paper, we propose a method of synchronizing the lip shape with voice by applying a SMS message received in mobile environments to 3D mobile Avatar. The proposed method enables to realize a natural and effective SMS message reading service of mobile Avatar by disassembling a received message sentence into units of a syllable and then synchronizing the lip shape of 3D Avatar with the corresponding voice.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.4
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• pp.684-702
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• 2011

This paper proposes a TDMA-based multichannel medium access control (MAC) protocol for QoS provisioning in mobile ad hoc networks (MANETs) that enables nodes to transmit their packets in distributed channels. The IEEE 802.11 standard supports multichannel operation at the physical (PHY) layer but its MAC protocol is designed only for a single channel. The single channel MAC protocol does not work well in multichannel environment because of the multichannel hidden terminal problem. Our proposed protocol enables nodes to utilize multiple channels by switching channels dynamically, thus increasing network throughput. Although each node of this protocol is equipped with only a single transceiver but it solves the multichannel hidden terminal problem using temporal synchronization. The proposed energy efficient multichannel MAC (EM-MAC) protocol takes the advantage of both multiple channels and TDMA, and achieves aggressive power savings by allowing nodes that are not involved in communications to go into power saving "sleep mode". We consider the problem of providing QoS guarantee to nodes as well as to maintain the most efficient use of scarce bandwidth resources. Our scheme improves network throughput and lifetime significantly, especially when the network is highly congested. The simulation results show that our proposed scheme successfully exploits multiple channels and significantly improves network performance by providing QoS guarantee in MANETs.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.138-147
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• 2003

There are some problems of current internet protocols to support the mobility of terminal in wireless environments. The mobile IP has come out to solve these problems, but there exists some problems like triangle routing, the need of each host's home address and the management of tunneling. Also. real-time multimedia traffics require fast hand-off, low latency and the utilization ratio of high bandwidth. SIP can support the mobility of wireless terminal and is widely accepted as the protocol which can support multimedia service and call setup in next generation network. In this paper, the framework of SIP system will be designed and implemented to support the mobility of wireless terminal by using JAIN API which follow the standards of next generation network and this system matches the standards of next generation network.

• Journal of the Korea Safety Management & Science
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• v.9 no.6
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• pp.155-162
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• 2007

Recently, retail store automation appliance market is changed with traditional POS systems techniques and RFID, radio POS system, and self checkout system, etc. in the foreign advanced distribution industry. Retailers and consumers require convenient POS system which can provide more functions and fast service. These requests bring to rapid evolution of various H/W and S/W corresponding with POS system. In this study with the POS systems and the RFID technology we develop core technology of movable u-POS system based on RFID that can use in large store. So we propose u-Cart system that can alternate the current shopping cart and POS terminal and that provide value added services to customer. As the result we present the configuration of u-Cart terminal device(WMDT : Wireless Mobile Data Terminal) including RFID reader module that can provide various information to consumer and some convenient client applications that are running in WMDT and u-POS administration service module.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.773-776
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• 2006

This paper has implemented a tour guide terminal using the embedded linux. The implemented terminal can locate its position using GPS interface and display the sightseeing information of the current location. With view of this implementation results, we confirmed the possibility of embedded linux terminal as a tour guide PDA. The realtime update of sightseeing information using a mobile communication functionality will be included in our future works.