• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.474-482
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• 2012

Mobile Gateway(MG) is a wireless LAN device to provide internet services to a passenger on vehicles like a bus. For using internet services, MG connects the Road Side Unit AP(RSU AP) based on WLAN .To provide a stable communication service on the moving vehicle, handoff changing MG's RSU must be handled fast and stably. However, it has a physical limits to remove a disconnection time of handoff process by reason of its technological features. In this paper, we suggest a MIMG(Multi-Interface Mobile Gateway) executing seamless handoff by using multiple wireless LAN interfaces for connecting RSU. In the detailed way to do stable handoff, we suggest the "Link Sharing Technique" to disconnection time of packet transmission for RSU to MIMG and the "Path Sharing Technique" to remove disconnection time of packet transmission for MIMG to RSU. we implemented the MIMG which performs the suggested handoff technique. We confirmed the superiority of our system by remove of the disconnection time(0 ms), and improved over 50 % of the communication bandwidth.

• Journal of KIISE:Software and Applications
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• v.34 no.1
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• pp.79-94
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• 2007

In the ubiquitous computing age which uses a high quantity network, mobile devices such as wearable and hand-held ones with a small tamers and a wireless communication module will be widely used in near future. Thus, a lot of researches about an augmented game on mobile devices have been attempted recently. The existing augmented games used a traditional 'backpack' system and a pattern marker. The 'backpack' system is expensive, cumbersome and inconvenient to use, and because of the pattern marker, it is only possible to play the game in the previously installed palace. In this paper, we propose an augmented game called Flying Cake using a face region to create the virtual object(character) without the pattern marker, which manually indicates an overlapped location of the virtual object in the real world, on a small and mobile PDA instead of the cumbersome hardware. Flying Cake is an augmented shooting game. This game supplies us with two types: 1) a single player which attacks a virtual character on images captured by a camera in an outdoor physical area, 2) dual players which attack the virtual character on images which we received through a wireless LAN. We overlap the virtual character on the face region using a face detection technique, and users play Flying Cake though attacking the virtual character. Flying Cake supplies new pleasure to flayers with a new game paradigm through an interaction between the user in the physical world captured by the PDA camera and the virtual character in a virtual world using the face detection.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.416-421
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• 2011

Nowadays, the increasing demands upon mobile devices such as wireless sensor networks and the recent advent of low power electrical devices such as MEMS make such renewable power sources attractive. A vibration-driven MEMS lead zirconate titanate $Pb(Zr,Ti)O_3$ (PZT) cantilever device is developed for energy harvesting application. This paper presents a piezoelectric based energy harvester which is suitable for power generating from conventional vibration and has in providing energy for low power electron ic devices. The PZT cantilever is used d33 mode to get the electrical power. The PZT cantilever based energy harvester with the dimension of 7 mm${\times}$3 mm${\times}$0.03 mm is fabricated using micromachining technologies. This PZT cantilever has the mechanical resonance frequency with a 900 Hz. With these conditions, we get experimentally the 37 uW output power from this device with the application of 1g acceleration using the 900 Hz vibration. From this study, we show the feasibility of one of energy harvesting candidates using PZT based structure. This PZT energy harvester could be used for various applications such a batteryless micro sensors and micro power generators.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.6
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• pp.2104-2117
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• 2014

The propagation of smart devices and the rapid expansion of wireless mobile networks have increased the need for ubiquitous device connectivity and contents access. DLNA is currently being used as the de facto standard for connectivity of consumer devices in the digital home. The guidelines provided by DLNA are intended to facilitate device and contents discovery, management, sharing and distribution. However, consumer experience with DLNA has been rather poor and usability not up to speed. Different problems and issues in limited compatibility have been reported due to manufacturer customizations. Such compatibility issues are often difficult to identify by average consumers who are not savvy in information communications and multimedia technology. In this paper, the design and implementation of a DLNA protocol inspection tool is presented for compatibility analysis among DLNA certified devices. The tool monitors the home network and performs analysis of the underlying protocols used by DLNA. The tool can be used for diagnostics and troubleshooting, enabling the user to identify compatibility issues between devices or problems in the network.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.126-127
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• 2013

In industry, Supervisory Control and Data Acquisition (SCADA) system plays critical role to ensure production is monitored and controlled rigorously and in timely manner. Having a cost saving yet still effective SCADA system would be much desired by Industry. SCADA itself is a field with constant development and research like how this paper investigates on creating an extremely low cost device, which can be adapted to many different SCADA applications through some very basic programming when combined with relevant peripherals. Much of the process in some expensive SCADA application based on smartphone application is due to specialized communication infrastructure. This paper addresses the needs by developing low cost and integrated wireless SCADA system. The system features capability on accessing the performance of remotely situated device parameter, such as temperature, control analog or digital input output on real time basis. We use existing mobile network capability through Bluetooth communication channel.

• Information Systems Review
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• v.9 no.2
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• pp.15-39
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• 2007

Mobile games have emerged as the most innovative entertainment technology, adding new revenue streams, taking advantage of the potential of wireless applications and service offerings. Mobile games, like any other types of computer game, offer a unique value for users in providing an exciting digital experience in virtual worlds. In this paper, we attempt to investigate the demographic factors which play critical roles in determining the level of playing times; classify mobile gamers based on their motives for playing games; and empirically test differences in their demographic factors and mobile game usage. Statistical results show that significant differences in playing times exist, depending upon their age, gender, mobile device, mobile phone usage, mobile game experiences, and preferred games genres. Applying Factor analysis, we have identified Escape, Social interaction, Challenge and Competition, Fantasy, Diversion and Relaxation, Ease of Accessibility as key motivators for playing mobile games. Additional cluster analysis shows that the categorization of gamers, according to their usage habits and the key motivators for playing, can be made as follows: Multi-gamers, Communication-focused gamers and Mobile active-gamers. Further correlation of these grouping with socio-economic data shows the significant differences in gaming habits and patterns of mobile phone use.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.257-260
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• 2004

This paper describes the software download framework for SDR(Software Defined Radio). SDR is expected to solve the compatibility problem among various mobile communication standards so that people can use the same device for different wireless network. We integrated the SDR software download process into Jini architecture, and modified Jini's several functions. We implemented this proposed framework on a Linux and windows operating systems with Java programming language. With Java platform, we can easily transfer this framework into hand-held devices.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.177-181
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• 2008

The more improved the Internet and the information technology, the stronger cryptographic system is required which can satisfy the information security on the platform of personal hand-held devices or smart card system. This paper introduces a case study of designing an elliptic curve cryptographic processor of a high performance that can be suitably used in a wireless communicating device or in an embedded system. To design an efficient cryptographic system, we first analyzed the operation hierarchy of the elliptic curve cryptographic system and then implemented the system by adopting a serial cell multiplier and modified Euclid divider. Simulation result shows that the system was correctly designed and it can compute thousands of operations per a second. The operating frequency used in simulation is about 66MHz and gate counts are approximately 229,284.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.448-450
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• 2005

A ubiquitous network allows all users to access and exchange information of any kind freely at any time, from anywhere, and from any appliance through the use of broadband and mobile access. Bluetooth commincation can provide the missing wireless extension to the heterogeneous network, allowing a more ubiquitous access. In this point of view, the BT specifications define ways for which each BT device can set up multiple connections with neighboring devices to communicate in a multi-hop fashion. this paper provides insights on the Bluetooth technology and on some limitations of the scatternet formations. so that, we describe a new multi-hop routing protocol for the establishment of scatternets. this protocol defines rules for forming a multi-hop topology in two phases. the first phase, topology discovery, concerns the discovery of the node's depth from a root node initiating inquiry process. the second phase forms scatternet topology based on the result of topology discovery.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2683-2684
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• 2004

심전도는 심장의 기능을 나타내는 중요한 생체전기신호의 일종이다. 이 논문에서는 Bluetooth 무선 규격을 사용하여 PC나 PDA로 송신이 가능한 휴대형 심전도 측정장치를 개발하였다. 개발된 시스템은 다채널 심전도를 측정하여 무선으로 전송하여 mobile device (PDA)나 PC 등에 실시간 디스플레이가 가능하다. 무선 전송에서 Bluetooth 규격을 사용함으로써 소형화 및 다중 채널로의 확장이 용이하고, 서로 다른 기기간의 간섭을 배재 할 수 있었다. 무선 전송기능과 이동성을 갖추고 있어 헬스기기나 실버의료기기 등 다양한 응용에 적용이 기대된다.