• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4B
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• pp.311-322
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• 2006

Peer-to-peer (P2P) systems have become a popular medium through which to share huge amounts of data. On the basis of network topology, P2P systems are divided into three types: centralized, structured distribution, unstructured distribution. Unstructured P2P systems such as Gnutella are novel in the sense that they are extensible and reliable. However, as the number of nodes increases, unstructured P2P systems would suffer from the high complexity of search operations that have to scan the network to find the required data items. Efficient replication of data items can reduce the complexity, but it introduces another problem of maintaining consistency among replicated data items when each data item could be updated. In this paper, we propose a new update propagation algorithm that propagates an updated data item to all of its replica. The proposed algorithm can reduce the message transfer overhead by adopting the notion of timestamp and hybrid push/pull messaging.

• KSCI Review
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• v.14 no.2
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• pp.215-224
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• 2006

Regarding a spam attack and the interception that a spinoff is largest among Vulnerability of VoIP at these papers study. Write scenario of a spam attack regarding VoIP Vulnerability, and execute Call spam. Instant Messaging spam, Presence spam attack. A spam attack is succeeded in laboratories, and prove. and confirm damage fact of a user in proposals of a spam interception way of VoIP service, 1) INVITE Request Flood Attack 2) Black/White list, 3) Traceback, 4) Black Hole-Sink Hole, 5) Content Filtering, 6) Consent based Communication, 7) Call act pattern investigation, 8) Reputation System Propose, and prove. Test each interception plan proposed in VoIP networks, and confirm security level of a spam interception. Information protection of VoIP service is enlarged at WiBro, BcN. and to realize Ubiquitous Security through result of research of this paper contribute, and may make.

• Safety and Health at Work
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• v.11 no.3
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• pp.284-290
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• 2020

Background: Prevalence rates of smokeless tobacco (SLT) use among firefighters are remarkably high and substantially higher than similar occupational groups and the general U.S. population. The purpose of this study was to explore the perspectives of fire service personnel regarding cancer and its associations with tobacco and SLT use. Methods: This descriptive study used a qualitative approach. Key informant interviews were conducted in 39 career firefighters and fire service administration from across the U.S. Discussion were recorded, transcribed verbatim and transferred to NVivo software for narrative analysis. Topics explored included cancer perceptions, attitudes and beliefs, and cultural factors related to SLT use behaviors. Results: Major themes that emerged among fire service personnel included concerns about cancer and its risk factors including firefighting tasks, such as fire overhaul operations, and from their lifestyle behaviors, such as alcohol and tobacco use. Firefighters also suggested a number of reasons for their increased SLT use, such as fire department tobacco-free policy and fire service culture. Conclusion: The current study provides a rich foundation for future research, prevention, and intervention efforts for the fire service and research communities regarding tobacco and SLT use and cancer risk. Additional research on firefighters' cancer beliefs deserves future research in order to improve messaging about the risks of cancer due to firefighting.

• The Journal of Society for e-Business Studies
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• v.10 no.2
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• pp.43-57
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• 2005

The web services concept is rising as a standard to integrate heterogeneous systems in distributed environment based on XML messaging. Recently, for that reason, many companies are trying to use web services for their B2C and B2B business. In order to successfully introduce the web services, it is required to guarantee a differentiated quality of web services. However, most of the current web services cannot provide differentiated policies for requested messages and the existing web servers cannot consider appropriately the quality factors of web services in the service level agreement between provider and consumer. In this paper, we analyzed appropriate quality factors of web services in application level and suggested priority allocation strategy for processes dealing with messages of web services using those factors. This strategy can allocate dynamically a priority to satisfy the service level agreement.

• The Journal of Society for e-Business Studies
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• v.11 no.4
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• pp.49-66
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• 2006

As business-to-business electronic commerce becomes activated, usage rate of standard electronic documents is rapidly increasing. Types and forms of standard documents exchanged between businesses have also been changed. Instead of EDI documents, mainly used in the initial phase, XML documents have been actively used recently. However, most framework standards for XML documents just specify basic syntax rules, messaging protocols, and standard documents. As a result, it has been usually difficult to procure efficiency and effectiveness in developing new standard electronic documents. Reflecting the experiences of developing UN/EDIFACT, UN/CEFACT provides a methodology and library for reusing standard data items as components when defining electronic documents. However, much additional effort is required for applying the methodology and library to the development process. In order to improve this situation, this paper proposes a system for supporting the development process by reusing various resources of registries/repositories, focusing on UN/CEFACT submission forms for standard electronic documents.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.113-119
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• 2017

The Rich Communication Service(RCS) is a next generation mobile messaging service. Since it has been developed and managed by a wireless service provider, 3rd party application developers cannot utilize the RCS features in their apps. A few studies have been proposed to solve this problem, even though they were not viable level of deployment. This paper presents a Web-based Rich Communication Service Software Framework(WebRSF) to help the 3rd party application developers adopt RCS features easily. WebRSF converts complicated RCS protocols to simple web-based protocols for providing the RCS 1-to-1 chat service to the 3rd parties. Communication protocols between WebRSF and its clients are defined in this paper. Also, a network configuration diagram and a message flow diagram are defined. Finally, performance evaluation between the WebRSF client and the RCS client are performed to simulate the load on clients' devices. It shows that the WebRSF client has 17% less loads than the RCS client while initiating sessions, and has 25% more loads after initiating sessions.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.451-460
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• 2006

Since low earth orbit (LEO) satellite constellations have important advantages over geosynchronous earth orbit (GEO) systems such as low propagation delay, low power requirements, and more efficient spectrum allocation due to frequency reuse between satellites and spotbeams, they are considered to be used to complement the existing terrestrial fixed and wireless networks in the evolving global mobile network. However, one of the major problems with LEO satellites is their higher speed relative to the terrestrial mobile terminals, which move at lower speeds but at more random directions. Therefore, handover management in LEO satellite networks becomes a very challenging task for supporting global mobile communication. Efficient and accurate methods are needed for LEO satellite handovers between the moving footprints. In this paper, we propose a new seamless handover management scheme for LEO satellites (SeaHO-LEO), which utilizes the handover management schemes aiming at decreasing latency, data loss, and handover blocking probability. We also present another interesting handover management model called satellite mobility pattern based handover management in LEO satellites (PatHO-LEO) which takes mobility pattern of both satellites and mobile terminals into account to minimize the handover messaging traffic. This is achieved by the newly introduced billboard manager which is used for location updates of mobile users and satellites. The billboard manager makes the proposed handover model much more flexible and easier than the current solutions, since it is a central server and supports the management of the whole system. To show the performance of the proposed algorithms, we run an extensive set of simulations both for the proposed algorithms and well known handover management methods as a baseline model. The simulation results show that the proposed algorithms are very promising for seamless handover in LEO satellites.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.249-256
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• 2020

The session initiation protocol (SIP) is a signaling protocol, which is used to controlling communication session creation, manage and finish over Internet protocol. Based on it, we can implement various services like voice based electronic commerce or instant messaging. Recently, Qiu et al. proposed an enhanced password authentication scheme for SIP. However, this paper withdraws that Qiu et al.'s scheme is weak against the off-line password guessing attack and has denial of service problem. Addition to this, we propose an improved password authentication scheme as a remedy scheme of Qiu et al.'s scheme. For this, the proposed scheme does not use server's verifier and is based on elliptic curve cryptography. Security validation is provided based on a formal validation tool ProVerif. Security analysis shows that the improved authentication scheme is strong against various attacks over SIP.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.187-195
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• 2020

Although multimedia messaging services (MMS) are becoming increasingly popular, and companies are maximizing the use of their content, few systematic studies on MMSs exist. This study examined technology acceptance factors for MMS in 398 young people aged 10 to 39 to identify MMS users' continuous intention to use (CITU) via a questionnaire and SPSS21 and PLS-Graph 3.0. The results showed that perceived media richness (PMR) had a positive effect on perceived usefulness, perceived ease of use, and most importantly, CITU. Furthermore, PMR had a positive effect on perceived ease of use as a moderating effect on experience. To increase use efficiency in MMSs based on these results, media richness, perceived ease of use, perceived usefulness, and user experience may serve as important variables affecting users' CITU and provide a basic reference and development direction for MMS users. Future studies should include more variables and examine additional factors when analyzing the structural model.

• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.65-73
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• 2007

This study evaluated the short message service (SMS) and multimedia message service (MMS) usability of mobile phones and wireless internet services by performance failure rates and flowcharts that adopted the concept of state diagrams. Forty-eight participants who had an experience of using mobile phones were recruited by posting an advertisement on websites for the experiment. They carried out both SMS and MMS tasks with the mobile phones of LG Cyon and Samsung Anycall as well as the wireless internet services of LGT ez-i, KTF magicN, and SKT NATE. In general, Cyon had the lower performance failure rate than Anycall for SMS, and ez-i had the lowest performance failure rate than the other services for MMS. More specifically through the workflow analysis, most participants used hot keys to take 7-8 steps to send a SMS including a symbol and had a difficulty in typing the symbol. They also took 10-11 steps to send a MMS after taking and attaching two pictures. Anycall, magicN, and NATE had significantly large error and failure rates due to the limited option of the menu paths that users could take and poor compatibilities of menu names and between menu and navigation keys. This study showed the possibility of use of flowcharts for systematic and specific usability evaluation methods and found the causes of performance errors and failures with mobile phones and wireless internet services to provide insight into their design.