• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.485-492
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• 2003

This paper proposes a transmission probability control scheme for guaranteeing fair packet transmissions in CDMA slotted ALOHA system. In CDMA slotted ALOHA system, the packets transmitted in the same slot act as multiple access interference, so that unsuccessful packet transmissions are caused entirely by multiple access interference. Therefore, in order to maximize the system throughput, the number of simultaneously transmitted packets should be kept at a proper level. In the proposed scheme, the base station calculates the packet transmission probability of mobile stations in the next slot according to the offered load and then broadcasts this probability to all the mobile stations. Mobile stations, which have a packet to transmit, attempt to transmit packet with the received probability. Simulation results show that the proposed scheme can offer better system throughput and average delay than the conventional scheme, and guarantee a good fairness among all mobile stations regardless of the offered load.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.381-388
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• 2003

Location tracking is used to keep track of the location information of a mobile terminal in an idle state for a cail setup between mobile terminals. In this paper, we introduce a location update algorithm based on the call arrival history, which is appropriate for a variable call arrival rate over time. The location tracking strategy which uses the proposed algorithm can find changes in the call arrival rate by maintaining a call arrival history of a mobile terminal, from which a mobile terminal can calculate an appropriate timeout interval for a variable call arrival rate. We show that the proposed scheme is appropriate for a variable call arrival rate by presenting a simple analytical model and analytical results to investigate its performance for both a fixed and a variable call arrival rate.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.163-169
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• 2012

Since only one application has monopoly on LCD device of the mobile device in Android platform, the user can not see two screens together displayed by two applications running simultaneously. In this paper, a dual-app has been defined as two mobile applications running on each device of a pair of two mobile devices and DSAP or Dual Screen Android Platform has been implemented. DSAP does remote-execution of the peer application of a dual-app on the peer mobile device when either application of the dual-app starts to run and supports communication of the pair app over the network. This paper describes details of design and implementation of DSAP and shows a sample case utilizing DSAP.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.469-472
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• 2008

Although wireless devices ar the most suitable for ubiquitous environment, they have restrictive capacities when using internet services than desktop environment. Considering different system features of mobile devices such as small display and limited input capability, an alternative scheme to access the Web efficiently is required. In the paper, we propose a mobile service method of S&T information content to support ubiquitous environment though the case study of KISTI's Scent of Science content service based on mobile.

• Korean Business Review
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• v.17 no.2
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• pp.203-228
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• 2004

This dissertation investigated the evaluation model of IT Service quality: concentrated on the quality components in mobile communication service. Today, mobile communication service is changing dramatically. The first and second generation's mobile communication services were designed for voice and SMS(Short Message Service). However, while the mobile communication industry grows, the mobile technology made more services available for customers. Customers' changing needs brought a new opportunities to the market. Now, mobile communication service is facing a new era as multi-functioning, multimedia service, and high speed data transfer service are being introduced. There has been a lot of theoretical literature on service quality components of mobile communication, but most of the literature was focused on the voice service and SMS(1st and 2nd generation). As mobile communication service evolves, the components may have to be altered or rebuilt. To identify which service quality components ought to be utilized, prior studies on service quality components, service quality, and customer satisfaction were reviewed. Also, a survey was conducted on the various aspects of mobile communication service. This study suggests 6 components of service quality: those are supporting facilities, cellular phone(facilitating goods), quality of the voice service(explicit service), supplementary services, supporting services, and cost. Empirical results supported that all of these components are proven as the service quality components, but, with regards to customer satisfaction, only cellular phone(facilitating goods) and supplementary services are effective. As previously stated, the relationship between service quality and customer satisfaction is also proven. This study is a point of departure for the success of upcoming generation's mobile communication service. It identifies what is valuable from the customer's point of view. Furthermore, it suggests some ideas to prepare for future market opportunities.

• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.85-98
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• 2007

In distributed computing paradigm, mobile surrogate systems have not gained wide acceptance because of security concerns that have not been suitably addressed yet. Currently even the widely used Grid middleware, Globus, does not have a host authentication mechanism, which makes it hard to provide high performance Grid computing capabilities to mobile clients. In this paper, a mobile Grid service framework is designed and implemented in order to provide Grid services to mobile host such as PDA. The surrogate host-based system allows mobile hosts to be provided with Grid services while moving. The implemented mobile Grid services system has been applied to mobile healthcare system which utilizes Grid computing for ECG signal processing. The presented system framework can be used as a secure enterprise mobile healthcare system for hospital physicians.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.522-528
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• 2004

Mobile internet service based on CDMA network evolution and multifunction mobile terminal is popular in Korea. Mobile internet service is classified as the information service using browser and mobile multimedia service using download platform. Killer applications based on multifunction mobile terminals have been developed for new business in mobile internet services. One of killer applications is location based seurvice (LBS) using mobile location information. In this paper, we develop mobile map browser using WIPI platform that is the main function in LBS. Mobile map browser interworking with GIS server provides the map information. The developed mobile map browser can be working on PDA and telematics terminals when WIPI is porting on these devices.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.75-80
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• 1999

Since a Holter monitor records a patients' ECG when he is in motion, it can monitor complex heart disease effectively. But it can not handle a sudden heart disease because the diagnosis process will be done only after 24 hours. So in this study, a model of ambulatory monitoring system using wireless data communication network is proposed. And a mobile ECG equipment and a doctors' terminal are developed for the proposed system implementation. As a result, we can evaluate that the proposed ambulatory monitoring system is suitable for the management of ambulatory patients who may be at risk form sudden cardiac abnormalities.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.296-300
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• 2004

In this paper, we discuss about mobile Internet security. The past few years have seen unprecedented growth in the number of wireless user, applications, and network access technologies. Wireless Internet is similar to wired internet, but it has some constrained wireless environment. So many internet technologies for wireless are developing now

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1338-1346
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• 2007

Beyond a simple voice service, the advances in performance and resolution of mobile handsets provides us various features in the field of mobile services. Also, advances in the human-machine interface, electronics and embedded system technologies have created the foundation for a dramatic shift in the way the vehicles are diagnosed and maintained. In this paper, we will show the vehicle diagnostic system using the mobile handset based on the OBD-II (On Board Diagnostics version II) protocol. After 2005, OBD-II standard is obligatory for all vehicles selling in Korea. Our research topics are OBD-II protocol converter for the mobile handset and the vehicle diagnostics system on WIPI(Wireless Internet Platform for Interoperability) mobile platform, which is the standard mobile platform in Korea.