• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.507-513
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• 2005

As the rapid increasement of the number of internet users has occured recently, many multimedia application services have been emerging. To improve quality of service, traffic can be suggested to be classified with priority in EPON(Ethernet Passive Optical Network), which is supporting the multimedia application services. In this paper, multimedia application services treat bandwidth classifying device in serving both delay sensitive traffic for real-time audio, video and voice data such as Von(Voice over Internet Protocol), and for real-time traffic such as BE(Best Effort). With looking through existing mechanisms, new mechanism to improve the quality will be suggested. The delay performances and packet losses of traffic achieved by supporting bandwidth allocation of upstream traffic in suggested mechanism will be analized with simulations.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.12
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• pp.1411-1416
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• 2015

Grayhole attack, one of attack to MANET routing function, is very severe in point of view of causing results which disturbs normal transmission function of network with uneasy finding of attacks. In this paper, effects of grayhole attack to application service on MANET is analyzed. Based on this analysis, some conditions is suggested for anti-intrusion to operate an application service on MANET under grayhole attack. This study is done with computer simulation based on NS-2 be added grayhole attack function which is implemented in this paper.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.65-72
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• 2008

Mobile Collaboration is an enabling technology that makes users share information between mobile devices and various Mobile P2P platforms have been designed and implemented for it. There are, however, few research papers on application of SIP protocol to spatial data sharing on mobile devices. In this paper, SIP based real time sharing framework is proposed to compose a mobile P2P platform on which spatial data can be trans(erred. A new protocol based on WKT and WKB is defined to send and receive spatial objects with SIP MESSAGE method. Base maps such as digital maps and parcel maps can be provided by a map server that is integrated with SIP server after a new SIP session established and client agents are registered. The framework proposed based onSIP enables users to transfer spatial data such as maps and satellite images directly between mobile devices during VoIP based voice call and therefore, mobile applications can be applied in various domains such asforest management and national defense.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.430-441
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• 2006

As the various A/V devices and home networks are delivered to users, home networks are changing to an entertainment network. It is expected that the required network bandwidth and the amount of usage of media content in home entertainment networks will be increased. Although the access networks and home networks becoming a high speed network, there remains the problems for QoS-guaranteed media content transfer in home networks. Also, in the home network, there can be network traffic caused by applications like video conferencing, video telephone, and VoIP(voice over IP) as well as inner network traffic of home network. Since media content transfer requires the real-time delivery, it is very important and basic requirement that is to transfer media content to A/V device user wants while keeping the media quality. Even though there are many middleware protocol for home networking, they provide basic device discovery and control or simple functions for QoS-guaranteed media content transfer that are not enough to provide QoS-guaranteed media transfer service that user wants. Thus, in this paper, we propose the technique based on UPnP(universal plug and play) protocol for QoS-guaranteed media content transfer in the home network. The proposed technique is compatible with UPnP and can be used with UPnP as additional functions. In this paper, we utilize VideoLAN application to verify the proposed technique. We add the additional modules that support the proposed technique's function to VideoLAN and we verify the its functions through various test scenarios.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.569-575
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• 2014

These days as smart TVs or android set top boxes have come into wide use, VoIP(Voice over Internet Protocol) services such as the Skype which can beused on computer system, can be also accessed by smart TVs or set top boxes. and the various kinds of distance learning programs have been developed on smart TVs or set top boxes. but when users have utilized a webcam with smart TVs or set top boxes, users have to go in front of smart TVs or set top boxes In this research paper, the new technology can be solved the problem of webcam use according to chaned environment. This tech is related with the wireless webcam one which can be applicable to open spaces such as living room with some distance between user and smart TV. There are few problems in long distance the test results show high reliability in living room with some distance.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.514-524
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• 2007

Recent advances in the speed of multi-rate wireless local area networks (WLANs) and the proliferation of WLAN devices have made rate adaptive, opportunistic scheduling critical for throughput optimization. As WLAN traffic evolves to be more symmetric due to the emerging new applications such as VoWLAN, collaborative download, and peer-to-peer file sharing, opportunistic scheduling at the downlink becomes insufficient for optimized utilization of the single shared wireless channel. However, opportunistic scheduling on the uplink of a WLAN is challenging because wireless channel condition is dynamic and asymmetric. Each transmitting client has to probe the access point to maintain the updated channel conditions at the access point. Moreover, the scheduling decisions must be coordinated at all clients for consistency. This paper presents JUDS, a joint uplink/downlink opportunistic scheduling for WLANs. Through synergistic integration of both the uplink and the downlink scheduling, JUDS maximizes channel diversity at significantly reduced scheduling overhead. It also enforces fair channel sharing between the downlink and uplink traffic. Through extensive QualNet simulations, we show that JUDS improves the overall throughput by up to 127% and achieves close-to-perfect fairness between uplink and downlink traffic.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.93-103
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• 2006

소비자의 하이테크 서비스 가입 이후 행태를 살펴보면, 가입자들은 서비스를 실제로 사용하기도 전에 가입 해지결정을 내리기도 한다. 최근 미국의 기간통신회사에서 출시된 인터넷전화 서비스의 경우, 출시 후 1년 반 동안 이탈한 고객 중 무려 60%정도가 서비스를 실제로 사용하기 전 상태인 네트워크 및 시스템이 준비되는 동안이나 소비자가 가정에서 전화기 연결용 어댑터를 설치하는 단계에서 이탈한 것으로 나타났다. 이와 같은 가입초기 고객의 이탈은 기업에게 고객획득과정에서 지출된 마케팅비용의 손실 및 미래의 매출감소뿐만 아니라, 기 가입자를 통한 미래의 가입 희망자에게 미칠 수 있는 긍정적 구전효과와 같은 간접효과에 대한 손실을 의미한다. 하지만 하이테크 서비스에 대한 소비자의 가입 후 행태에 대한 기존연구는 고객불평 연구, 서비스 사용 후 발생하는 정상적 이탈행태(normal churn)에 대한 연구, 또는 탐색적 연구를 제외하면 매우 부족하다. 더욱이 하이테크서비스의 특성을 고려한 서비스 출시초기에 소비자의 가입직후 해지결정에 대한 결정요인 연구는 그 필요성에 비해 연구가 전무하다시피한 실정이다. 본 연구에서는 하이테크 서비스에 대한 소비자의가입시점과 실제 사용시점 사이에 발생하는 소비자의 이탈행태를 이탈시점에 따라 '가입직후 이탈(immediate churn)' 과 '가입 후 이탈(earlychurn)'로 정의한 후, 특히 가입직후 고객의 이탈행태를 설명하기 위해 하이테크 서비스에 대한 소비자의 이전 사용경험정도와 서비스에 대한 정보를 획득한 채널의 정보전달 풍부성 등을 연구모형에 포함하였다. 이 기간 동안에 기업은 서비스 제공에 필요한 부수적인 기기 제공 및 서비스 준비 등을 수행하지만, 동시에 소비자는 여러가지 이유로 가입결정을 제고할 수도 있게 된다. 제안된 연구모형에 대한 실증분석을 위해 미국 유수의 기간통신회사에서 2004년 출시된 인터넷전화(Voice over Internet Protocol: VoIP)서비스에 가입한 12,000여명 의 고객 프로파일과 서비스사용 데이터를 활용하였다. 분석결과 가입자의 하이테크 서비스에 대한 사용경험정도가 낮을수록 서비스 가입직후 바로 해지하는 경향을 보였다. 하지만 하이테크 서비스에 대한 이전 사용경험이 낮은 경우라도, 가입 후서비스를 실제로 사용하였다면 서비스에 대한 가입해지 경향은 더 이상 나타나지 않았다. 이는 가입자의 하이테크 서비스에 대한 이전 사용경험정도가 가입직후 해지에만 영향을 미치는 요인임을 보여준다. 또한 매체의 정보전달 풍부성 (media richness)이 상대적으로 높은 소매점이나 웹사이트를 통해 서비스에 가입한 소비자일수록 가입 직후뿐만 아니라 서비스사용 이후에도 낮은 해지성향을 나타냈다. 이러한 분석결과를 바탕으로 인터넷전화 서비스에 적합한 고객지원 프로그램 설계와 마케팅 매체선정과 관련한 전략적 시사점을 도출한다. 그리고 국내에서 최근 이슈가 되고 있는 차세대 무선인터넷 서비스인 와이브로 출시에 따른 마케팅 및 고객관리와 관련된 시사점을 논의한다.