• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.519-527
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• 2013

Mobile radio technologies have evolved in the railway industry offering seamless connectivity and various functionalities to improve railway service. Recently, advanced mobile communication technologies have enabled a new level of railway customer services with more efficient railway operation. Since the LTE mobile communication technology offers many benefits and better performance for new railway services, it is considered to be a strong candidate for the future railway mobile telecommunication. However, communication networks in the railway sector are critical for secure operation and have stringent requirements for reliability and safety. In this paper, we explain the requirements for the future railway mobile telecommunication. The LTE, which would be the future railway mobile technology, is analyzed against these requirements. We also introduce the current state of standardization for the future railway mobile telecommunication and its implementation plan.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.355-364
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• 2005

An example of such a new device is a mobile phone. The demand for wireless data communication is growing rapidly. However, agencies have not yet completed the standardization of the markup language. Due to the evolution of the Mobile Device, the agencies in this field have provided different data formats with each Mobile Device Platform. Traditionally, contents are hand-tailored to suit the target devices. A key problem is that the characteristics and capabilities of mobile devices are too diverse to service the most suitable mobile contents. Owing to this problem, the need for a reusable document description language increases. In this paper, we defined Template file that is common data to service mobile devices. We proposed method that could be effective wireless web service though design and the implementation of the Call Manager & the XSL Generator. In the methodology, when requesting wireless internet service, the mobile device finds out Markup language and hardware specification of the mobile device through the Call Manager component supports. The XSL Generator component creates XSL file dynamically that is the most suitable to device. Finally, contents is serviced to each device by XSLT.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.47-54
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• 2004

By using wireless terminal, the number of users who wish to use the multimedia service like the Internet as well as Short Message Services and voice service has increased dramatically over the last years. We propose the method that improves Mobile IPv4 (MIPv4) Regional Registration in wireless mobile networks to decrease traffic's transmission delay and message generation compared with an existing method We design the scheme in MIPv4 environments that a packet do not pass through the home agent transmitted from correspondent node to mobile node, if a mobile node moves to other mobility agent. Simulation results show that the proposed method significantly reduces the expenses for registration and delivering packet.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.141-147
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• 2004

Recently, Mobile phone became a great member of people. It is increased an use of mobile phone a population. According to mobile phone service. Also a carrying along like CDMA terminal became a small size. a light weight. A phone increased in an environment mobile phone service. For the reason it is demand as necessary evaluation iterms development and test environment construct. In this thesis. mobile phone service an environment is necessary an test principal and interest. wireless network is used Wireless Data. To recommand a Wireless Data quality evaluation method and to look upon next generation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.929-935
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• 2006

When the Internet phone service, generally PC-to-Phone, first entered into the telecommunications service market, no regulatory issues were arisen to manage the service within the regulatory framework because of it's low quality, no phone number assignment and etc. However, almost the same quality, more applications and cheaper price compared with the fixed telecommunications service, have changed the regulator's policy allowing Internet phone service within market mechanism. While incumbent fixed telecommunications service enterprises had given with tremendous duties to continue the job categorized 'facilities-based telecommunication service provider', and which can be unreasonable and unfair if Internet phone service enterprises are allowed to enter into the fixed telecommunications market without any regulation. Thus, new regulatory framework has worked for the Internet phone service named the VoIP service generally in the fixed telecommunications market. Recently, VoIP is provided not only in the fixed telecommunications market but also in the mobile market as Wi-Fi phone is feasible in the wireless LAN environment. Furthermore, bundled service of Wi-Fi and cellular phone service will be launched soon, and the next version will be the mobile VoIP service operating like a cellular phone service. Hence, we will meet similar situation when the VoIP sewice enters into the fixed telecommunications service market. And, in this paper, we prospect the regulatory issues arising when the wireless or mobile VoIP service enterprises enter the mobile market, by analyzing possible scenarios.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.379-383
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• 2004

Mobile Internet has different platform cause interrupt activation of mobile internet because contents providers have each different development environment. To use of WIPI(Wireless Internet Platform for Interoperability) developer by KWISF(Korea Wireless Internet Standard Forum) founded to solve this problem guarantee independence of hardware and interpretation of mobile application. In this paper, we research method to activate WIPI which is standard platform to develop applications easily and efficiently in mobile environment and we implement WIPI application to show the excellent of WIPI in mobile development environment.

• Journal of Communications and Networks
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• v.14 no.2
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• pp.179-187
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• 2012

Power saving is one of the most important features that extends the lifetime of portable devices in mobile wireless networks. The IEEE 802.16e mobile broadband wireless access system adopts a power saving mechanism with a binary truncated exponent algorithm for determining sleep intervals. When using this standard power saving scheme, there is often a delay before data packets are received at the mobile subscriber station (MSS). In order to extend the lifetime of a MSS, the battery energy must be used efficiently. This paper presents a dynamically alternating sleep interval scheduling algorithm as a solution to deal with the power consumption problem. We take into account different traffic classes and schedule a proper sequence of power saving classes. The window size of the sleep interval is calculated dynamically according to the packet arrival rate. We make a tradeoff between the power consumption and packet delay. The method achieves the goal of efficiently reducing the listening window size, which leads to increased power saving. The performance of our proposed scheme is compared to that of the standard power saving scheme. Simulation results demonstrate the superior performance of our power saving scheme and its ability to strike the appropriate performance balance between power saving and packet delay for a MSS in an IEEE 802.16e mobile broadband wireless access system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1027-1030
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• 2005

The article introduces developing trends of an adaptive mobile terminal as an interface for use of various network resources, such as public wireless networks and un-licensed wireless networks in ubiquitous sensor network environments, without troublesome settings or operations by users. These adaptive mobile terminals able to provide seamless services that adapt autonomously to the user's movements and changes in the state of wireless resources. Consequently, adaptive mobile terminals should be had respective independent hardware structure of usable wireless networks.

• Journal of Information Processing Systems
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• v.2 no.3 s.4
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• pp.159-162
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• 2006

Wireless LANs are becoming more widespread because of the rapid advance of wireless technologies and mobile computers. In this paper, we present the design and implementation of a system to help mobile users to select the most competent AP. By monitoring the network traffic of APs within the local LAN in real time, this system offers the mobile user the network utilizations, locations, and signal strengths of APs online. Based on the information, the user can select a competent AP with a high wireless bandwidth. Finally, we verified the accuracy of monitoring and calculating with regard to the utilizations of APs through real experiments.

• ETRI Journal
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• v.28 no.2
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• pp.205-215
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• 2006

Wireless data communication (WDC) services are increasingly penetrating the market. The two main alternative WDC technologies are wireless LAN and mobile Internet. Services based on these technologies display differences in quality attributes such as terminal device, data transmission speed, pricing scheme and so on. How consumers choose between these two alternatives will be determined by their preferences regarding such quality attributes. In turn, their preferences will affect the evolution of WDC services and related technologies. This study employs a conjoint analysis of consumer valuations of quality attributes of wireless LAN and mobile Internet services. Respondents rate hypothetical service alternatives featuring various combinations of quality attributes. By estimating consumer willingness to pay for the attributes of WDC services, the authors predict the evolution of WDC services and related technologies along various quality dimensions, make a comparison with the results of a previous study, and draw policy implications for national-and company-level R&D strategies.