• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.245-250
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• 2003

Of all wireless technologies for personal communications, CDMA(Code Devision Multiple Access) offers the best combination of good signal quality, high security and system reliability. CDMA2000 provides Internet and internet services for variable multimedia aplications. However, good educational CDMA web contents, which focus on the easy understability and good readability, are rare dute to the difficulties and the broad range of CDMA technologies. This content is developed based upon the following two aspects. First, a basic CDMA communication theoy, which contains much color figures and animation, is introduced combing the experimental results and corresponding explanations utilizing the information obtained by the TIMS CDMA equitments. It can improve the understabiliy virtual experience of the site visitors interested in the CDMA. Secondly, the recent CDMA coverage prediction and engineering technology is introduced using the RF plan tool C24 combined for the CDMA engineers

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.348-352
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• 2008

In distributed computing paradigm, mobile surrogate systems migrates from on host in a network to another. However, Mobile surrogate system have not gained wide acceptance because of security concerns that have not been suitably addressed yet. In this paper, we propose a security framework based on Grid Proxy Gateway for mobile Grid service. The current Grid Security Infrastructure is extended to mobile computing environments. The surrogate host system designed for mobile Personal Digital Assistant (PDA) users can access the certified host and get his proxy credential to launch remote job submission securely.

• Journal of the Semiconductor & Display Technology
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• v.7 no.3
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• pp.59-63
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• 2008

Geo-coding refers to the process of associating data with location information, and the system deals with geographic identifiers expressed as latitude and longitude or street addresses. Although many services have been launched, there still remains a problem for users to create geo-coded photo with manually labeling GPS(Global Positioning System) coordinate or synchronizing with separate devices. In this paper, we design and implement a geo-coding system which utilizes the time and location information embedded in digital photographs in order to automatically categorize a personal photo collection. An included GPS receiver labels a photograph with its corresponding GPS coordinates, and the position of the camera is automatically recorded into the photo image header at the moment of capture. The place and time where the photo was taken allows us to provide context metadata on the management and retrieval of information.

• Electronics and Telecommunications Trends
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• v.9 no.4
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• pp.139-146
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• 1994

통신의 개인화 실현에 가장 중요하고도 기본적인 요구 조건은 통신 주체의 이동성을 확보하는 것이다. 이러한 이동성은 단말의 이동성과 개인의 이동성이라는 두가지 서로 다른 성격의 이동성이 모두 보장될 때 완전하게 된다. 차세대 개인 통신에 대한 연구는 ITU-T/R의 UPT와 FPLMTS에 의하여 대표된다. UPT는 이용자에게 개인의 이동성을 제공해 주는 서비스인데 비하여, FPLMTS는 무선 단말의 이동성을 제공하는 시스템이다. 이들은 모두 차세대 개인 통신의 기본적인 기능인 이동성을 제공하지만 서로 독립적이며, 상호 보완적인 개념들이다. 본 고에서는 차세대 개인 통신에 대한 개념과 연구 동향을 분석, 소개하였다. 특히 ITU-T/R에서 표준화 노력을 경주하고 있는 UPT, FPLMTS를 단말의 이동성과 개인의 이동성 측면에서 소개하고 그들간의 상호 관계를 분석하였다.

• The Journal of Information Technology
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• v.10 no.4
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• pp.11-26
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• 2007

EDS is a typical convergence service performing convergence between functions owned by multiple SPs. EDS provides users with the relevant information and the communication by the various personal conditional environment. An alternative terminology for events for net- work related applications is 'triggers'-these are assumed to be included in the present description. Events could be defined as any activities which occur within a service avail ability, signals. Events can be managed, for example, as part of a context-aware application. EDS carry out a procedure for processing user's requested information about mobil network-based entities, such as the combination with various applications, such as a LBS (Location Based Service) and area information. In AS (Application Service) network environments, the user has his customized EDS in the network, the EDS automatically connects the appropriate Terminals consistent with a user profile. EDS can also send the collected information to other requesting users by way of event information and using the procedures of combination with other services. The user can record/retrieve the user-related information to from the information base through EDS.

• ETRI Journal
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• v.33 no.6
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• pp.871-879
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• 2011

Because a wide variety of multimedia services are provided through personal wireless communication devices, the demand for efficient bandwidth utilization becomes stronger. This demand naturally results in the introduction of the variable bitrate speech coding concept. One exemplary work is the selectable mode vocoder (SMV) that supports speech/music classification. However, because it has severe limitations in its classification performance, a couple of works to improve speech/music classification by introducing support vector machines (SVMs) have been proposed. While these approaches significantly improved classification accuracy, they did not consider correlations commonly found in speech and music frames. In this paper, we propose a novel and orthogonal approach to improve the speech/music classification of SMV codec by adaptively tuning SVMs based on interframe correlations. According to the experimental results, the proposed algorithm yields improved results in classifying speech and music within the SMV framework.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.737-747
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• 1997

performance of the cellular CDMA overlay system is analyzed which shares the same band with existing microwave narrowband system to enhance the spectral efficiency. To suppress the interfreence from narrowband system, we used a linear predicition filter that adopts the adaptive least mean square algorithm. Alalyzing the performance in the Personal Communication Services channel, characterized as a multipath Rician fadng channels, we considered the power control to solve the near-far problem, and-off and multipath diversity. We also considered interleaving and channel coding to improve BER performance of the CDMA system.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.163-172
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• 2004

Ultra Wide Bandwidth (UWB) spread-spectrum techniques will playa key role in short range wireless connectivity supporting high bit rates availability and low power consumption. UWB can be used in the design of wireless local and personal area networks providing advanced integrated multimedia services to nomadic users within hot-spot areas. Thus the assessment of the possible interference caused by UWB devices on already existing narrowband and wideband systems is fundamental to ensure nonconflicting coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. In this paper, we study the coexistence issues between an indoor UWB-based system (hot-spot) and outdoor point to point (PP) links and Fixed Wireless Access (FWA) systems operating in the 3.5 - 5.0 GHz frequency range. We consider a realistic UWB master/slave system architecture and we show through computer simulation, that in all practical cases UWB system can coexist with PP and FWA without causing any dangerous interference.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.581-587
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• 2021

Real-time video streaming scheme for multimedia content delivery and remote conference services is one of technologies that are significantly sensitive to data transmission delay. Recently, because of COVID-19, real-time video streaming contents for the services are significantly increased such as personal broadcasting and remote school class. In order to support the services, there is a growing emphasis on low transmission delay and secure content delivery, respectively. Therefore, our research proposed a packet aggregation algorithm to reduce the transmission delay of selectively encrypted video transmission for real-time video streaming services. Through the application of the proposed algorithm, the selectively encrypted video framework can control the amount of MPEG-2 TS packets for low latency transmission with a consideration of packet priorities. Evaluation results on testbed show that the application of the proposed algorithm to the video framework can reduce approximately 11% of the transmission delay for high and low resolution video.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.91-101
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• 2009

MMS (Multimedia Messaging Services) is one of the most basic services of mobile communication as well as a promising m-commerce enabling service. In our study, we hypothesize that the personality-based and cognitive traits of TAM and social cognitive theory are antecedents to MMS acceptance asking: what are the key determinants of intention to use MMS? An empirical investigation of 1,016 mobile phone users in South Korea was conducted. PLS results provided support for the effects of self-efficacy, perceived ease of use, relative advantage, credibility on attitude toward MMS use and strong support for the effect of attitude toward intention to use MMS. Our results provided a detailed account of the key forces underlying users intention to use MMS including personal and cognitive trait measures. Theoretical and practical implications of these findings are discussed in the paper.