• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.266-271
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• 2007

In mobile channel environments, the effect of the multi-path fading reduces the performance of the mobile communication severely. Previous studies on the effect of the multi-path fading show that, only the channel between fixed base stations and mobile terminals are considered. However, the future mobile communication service such as telematics may use the communication between moving mobile terminals, so called mobile ad-hoc communication, the studies on the channel is required for such situations. In this paper we have measured the mobile channel and analyzed the fading characteristics when using the linear array antennas. In the data measurements, we sent the QPSK modulated signal with carrier frequency of 2GHz band and received the signal using the array antennas equipped on moving vehicles. We have analyzed the fading characteristics and the effects of the fading reduction using the CDF of fading depth using data collected from two moving vehicles. The simulation results show that the beamforming technique adds 6 or 7dB to the fading margin than that of the selection diversity depending on channel environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.61-72
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• 2018

The purpose of this study is to analyze the impact of quality and satisfaction of mobile telecommunication service on the quality data sharing for mobile telecommunication service. Based on the theory of reasoned action(TRA), we proposed a research model that (1) service qualities significantly influence the service satisfaction and the attitude towards information sharing, (2) the attitude towards information sharing mediates between service satisfaction and the intention of information sharing, and (3) the intention of information sharing is affected by the service satisfaction and the attitude towards information sharing. Empirical analysis of mobile service users showed that the data quality of mobile communication services had a greater impact on satisfaction than voice quality. The service satisfaction had a positive effect on attitude towards information sharing and the intention of information sharing. Also, the attitude towards information sharing had a positive impact on the intention of information sharing. Based on this empirical study, we proposed a crowdsourcing as an alternative when quality data of mobile telecommunication service should be collected to improve telecommunication policy because by using collective intelligence of the crowdsourcing the government can gather more accurate and diverse data on mobile telecommunication service.

• Information Systems Review
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• v.8 no.2
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• pp.1-15
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• 2006

Schedule Management for outside duty personnels and their groups is fairly difficult since they spend most of their time on working outside individually rather than inside office. Everytime when schedule change for personnels or their groups is needed, it is necessary to call every personnel in order to notify the schedule change. It would be much easier to handle the schedule management problem if outside duty personnels are able to download schedule of their groups(and, upload their schedule) using their mobile communication devices such as PDAs. In this paper, using a data synchronization protocol in mobile communication environments, a schedule management system for outside duty personnels is designed and implemented. Data synchronization in mobile communication environments is a process of maintaining consistency between data stored in mobile devices and data stored in a (central) server at office. In other words, using SyncML data synchronization protocol proposed by OMA(Open Mobile Alliance) as an open standard for data synchronization in mobile communication environments, a schedule management system for outside duty personnels which allows them to check schedule of their groups and to notify their schedule to their groups at anytime anyplace is designed and implemented.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.365-371
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• 2012

In recent years, researchers have been attracted to clustering methods to improve communication and data transmission in a network. Compared with traditional wireless networks, wireless sensor networks are energy constrained and have lower data rates. The concept of implementing a clustering algorithm in an existing project on gateway relocation is being explored here. Low energy adaptive clustering hierarchy (LEACH) is applied to an existing study on relocating a gateway. The study is further improved by moving the gateway to a specific cluster based on the number or significance of the events detected. The protocol is improved so that each cluster head can communicate with a mobile gateway. The cluster heads are the only nodes that can communicate with the mobile gateway when it (the mobile gateway) is out of the cluster nodes' transmission range. Once the gateway is in range, the nodes will begin their transmission of real-time data. This alleviates the load of the nodes that would be located closest to the gateway if it were static.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.241-246
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• 2009

Advances in mobile and wireless networking technologies have enabled mobile ad hoc networks applicable to a wide range of areas. Many cases of even such ad hoc networks demand to be accessible to the global network. Owing to be diversified in features depending on applications, however, some those networks may consist of devices or nodes which do not facilitate all the same transport protocols. This results in unreachable situations of establishing ad hoc network: such as non-existence of all required access points, faults or contention in a path of particular protocol communication. Interworking between different transport protocols can alleviate such problems. This paper proposes an interworking scheme to improve data transport performance and network accessibility, especially in such a mobile ad hoc network that is applicable to data communications among ships or user's convenient u-health services. Modeling and simulation analysis are used to verify the improvement.

• Journal of the Korean Data and Information Science Society
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• v.18 no.3
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• pp.757-766
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• 2007

Location services are used in mobile ad hoc and hybrid networks to locate either the geographic position of a given node in the network or a data item. One of the main usages of position location services is presented in location based routing algorithms. In particular, geographic routing protocols can route messages more efficiently to their destinations based on the destination node's geographic position, which is provided by a location service. In this paper, we propose an adaptive location service on the basis of fuzzy logic called FHLS (Fuzzy Hierarchical Location Service) for mobile ad hoc networks. The adaptive location update scheme using the fuzzy logic on the basis of the mobility and the call preference of mobile nodes is used by the FHLS. The performance of the FHLS is to be evaluated by a simulation, and compared with that of existing HLS scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.207-211
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• 2000

The mobile communication technology which provides various data service and satifies the required quality in wireless environment can be classified as the forth generation mobile communication technology the forth generation communication technology must has diference with the 2nd and 3nd generation mobile communication technology. It must has the more advanced and more united shape than 3nd generation mobile communication. The forth generation mobile communication technology include following technology: Adaptive coding ar modulation, Smart antenna, Interference cancellation, Advanced handoff mechanism between networks. In this study, I represent the development and standardization of this technology.

• Journal of the Korean Professional Engineers Association
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• v.27 no.1
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• pp.5-12
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• 1994

In the high degree information society of the 21st century, along with the social activity becoming much more closer, our life style will also be very much changed. Recognition for obtaining various informations rapidly will be anticipated to enhance and the progress of a mobile communication system is greatly expected. This will enable the system to give and receive ″whenever, wherever, whomever, whatsever information.″ In our country, the car telephone and personal mobile communication services of radio calling etc. are diversified by the telecommunication system reformation and by the introduction of competive principle of the hereafter of 1988. Moreover, in accordance with the tariff, the number of subscrier is rapidly increasing. On the other hand, on the utility side of business, for the realization of a mobile communication which is abundant in functional nature, not only the hitherto voice but also non voice system of data communication is being introduced. The Ministry of Communications of Korea has been expediting the effective utilization of limited frequency band of qusai microwave band etc. as a concrete measures for an ever increasing demand. At the same time, to disseminate and promote a mobile communication most effectively, convenience, economic, and safety nature of the system, and in addition to these, international standardization is considered. For constitution of a new mobile communication, the Ministry has been promoting various policies designed for the digitalization of system, utility extention for home. personal level.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.338-341
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• 2005

Recently there are increasing needs for Internet and various kinds of contents. These traffics for various contents need more amount of data to provide high-quality information and require various QoS depending on the characteristics of contents. However, current Internet service supports BE (Best Effort) service only, therefore IntServ (Integrated Service) scheme and DiffSserv (Differentiated Service) scheme are represented to support QoS in IP layer. This paper describes new scheme that provides QoS taking into account the traffic characteristics over Mobile IPv6 network based on IEEE 802.11e by decreasing signal process time using traffic class of DiffServ and evaluates the performance through computer simulation.

• Information Systems Review
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• v.12 no.1
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• pp.145-164
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• 2010

Since the third generation (3G) mobile communication service has been launched by most mobile communication operators in Korea, the portion of data service in mobile communication service becomes one of the most important factors in mobile communication service market. In past mobile communication market, most mobile communication operators made their profit mostly from voice communication service. However, the portion of profit from data service has gradually increased based on both video phone call and mobile Internet service. In this situation, LG telecom launched the full browsing mobile Internet service. This service provides a new type of mobile Internet service platform which enables to access the World Wide Web using mobile browsers, so we generally access the Web using web browsers in the desktop computer. Under the open network structure of mobile Internet like situation, it is very important to analyze the factors which can affect the competition between mobile communication service companies. So, in this paper, we first present the current state of full browsing service, followed by the expectation of its growth potentials and barriers. Then, we analyze the advantages and disadvantage of LG telecom as a first-mover and SK telecom/KTF as followers. Finally, based on this analysis, we predict the future competition among these companies and the market.