• Journal of Broadcast Engineering
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• v.14 no.6
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• pp.796-806
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• 2009

SVC (Scalable Video Coding) is a new video coding standard to provide convergence media service in heterogeneous environments with different networks and diverse terminals through spatial-temporal-quality combined flexible scalabilities. This paper presents the performance analysis on packet loss in the delivery of SVC over IP networks and an efficient adaptation method to packet loss caused by buffer overflow. In particular, SVC with MGS (Medium Grained Scalability) as well as spatial and temporal scalabilities is addressed in the consideration of packet-based adaptation since finer adaptation is possible with a sufficient numbers of quality layers in MGS. The effect on spatio-temporal quality due to the packet loss of SVC with MGS is evaluated. In order to minimize quality degradation resulted by packet loss, the proposed adaptation of MGS based SVC first sets adaptation unit of AU (Access Unit) or GOP corresponding to allowed delay and then selectively discards packets in order of importance in terms of layer dependency. In the experiment, the effects of packet loss on quantitative qualities are analyzed and the effectiveness of the proposed adaptation to packet loss is shown.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.750-761
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• 2011

Currently, 3DTV technologies are being developed as the future services of the HD digital broadcast environment. As one of the various research topics to apply 3DTV technologies to the conventional broadcasting network, methods to configure stereoscopic videos are being studied. In this paper, we proposed a method to broadcast high quality stereoscopic videos based on analysis of a method to add a stereoscopic descriptor to the PMT of MPEG-2 transport streams and a method to transmit stereoscopic videos by the expansion of MPEG-C part 3 which are from precedent studies. The proposed technique maintains compatibility with conventional MPEG-2 transport streams by showing only reference video for models that do not support 3D broadcasting. Therefore, the compatibility between conventional broadcasting and stereoscopic videos should make this method useful when activating 3D services in the communications and broadcasting area

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.21-27
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• 2003

분산컴퓨팅, 다자간 협업, 대용량 고품질의 컨텐츠 교환을 지원하는 P2P는 차세대 인터넷의 핵심 어플리케이션이 될 것이다. 본래 인터넷의 근본이었던 IP 라우팅도 P2P 방식이었다. 장비가 다양해지고, PC가 증가하게 됨에 따라 동적 IP를 사용하거나, 하나의 IP를 여러 사람이 공유하여 사용하는 복잡한 방식을 취하기 시작했다. 그러나 새로운 IP 주소들이 충분히 공급될 수 있다면, 하나의 장치 당 하나의 주소 체제가 다시 각광을 받게 될 것이고, 지금처럼 불규칙적인 동적 IP 주소를 활용하지 않아도 될 것이다. 그런 의미에서 IPv6는 풍부한 주소자원을 각 단말에 부여할 수 있어, IPv16 기반의 P2P 구축은 P2P의 성능을 최적화하는 방법이 될 것이다. 현재 P2P는 콘텐츠 공유 및 전달, 네트워크/장치(하드디스크, CPU) 리소스 공유, 다자간 원격협업, 검색, 호스팅 및 프로젝트 관리 등 다양한 방법으로 활용되고 있다. 2000년경부터 대두되기 시작한 P2P 애플리케이션은 지난 2년 동안 급속하게 늘어났으며, 특히 인터넷 사용자들은 컨텐츠를 공유/전달할 목적으로 P2P를 많이 사용하고있다. 그러나 컨텐츠의 공유에 있어 MP3, 동영상, 이미지의 전달 및 공유에 그치고 있어, P2P를 기업 환경에서 지식공유 및 전달을 위한 시스템으로 활용하는 경우는 아직 미약하다. 그러므로 본 논문에서는 조직 내에서 정보활용 능력을 제고하기 위한 방안으로 P2P 시스템을 정보 공유 시스템으로 팔용하고, P2P의 성능을 최적화 할 수 있는 IPv6 기반의 개발 방안을 제안하고자 한다. 본 IPv6 기반의 정보 공유 P2P는 IPv6 전문가 그룹을 통해 시범적으로 적응하는 것으로 시작해, 학교 및 연구소를 통한 정보지식 공유 그리고 기업 정보화 솔루션으로 활용 될 수 있다.을 제시한다. 이렇게 함으로써 최대한 고객 납기를 만족하도록 계획을 수립할 수 있게 된다. 본 논문에서 제시하는 계획 모델을 사용함으로써 고객 주문에 대한 대응력을 높일 수 있고, 계획의 투명성으로 인한 전체 공급망의Bullwhip effect를 감소시킬 수 있는 장점이 있다. 동시에 이것은 향후 e-Business 시스템 구축을 위한 기본 인프라 역할을 수행할 수 있게 된다. 많았고 년도에 따른 변화는 보이지 않았다. 스키손상의 발생빈도는 초기에 비하여 점차 감소하는 경향을 보였으며, 손상의 특성도 부위별, 연령별로 다양한 변화를 나타내었다.해가능성을 가진 균이 상당수 검출되므로 원료의 수송, 김치의 제조 및 유통과정에서 병원균에 대한 오염방지에 유의하여야 할 것이다. 확인할 수 있었다. 이상의 결과에 의하면 고농도의 유기물이 함유된 음식물쓰레기는 Hybrid Anaerobic Reactor (HAR)를 이용하여 HRT 30일 정도에서 충분히 직접 혐기성처리가 가능하며, 이때 발생된 $CH_{4}$를 회수하여 이용하면 대체에너지원으로 활용 가치가 높은 것으로 판단된다./207), $99.2\%$(238/240), $98.5\%$(133/135) 및 $100\%$ (313)였다. 각각 두 개의 요골동맥과 우내흉동맥에서 부분협착이나 경쟁혈류가 관찰되었다. 결론: 동맥 도관만을 이용한 Off pump CABG를 시행하여 감염의 위험성을 증가시키지 않으면서 영구적인 신경학적 합병증을 일으키지 않았고 좋은 혈관 개존율을 보여주었다. 따라서 동맥 도관을 이용한 Off pump CABG는 관상동맥의 협착의 정도에 따라 효율적으로 시행 시 좋은 임상결과를 얻을 수 있을 것으로 생각된다.였다. 그러나 심근 기능이나

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.1
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• pp.72-85
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• 2012

Today, although most bluetooth hands-free devices within a vehicle provide telephone service functions such as voice communication, caller id display and SMS message display and so on, they do not provide a function that displays Internet-based text data. We need to develop a scheme that displays the internet-based text data including existing hands-free function because the request for using the Internet service is increasing within a vehicle recently. The proposed bluetooth device application includes advanced function such as SNS message arrival notification, the message display function and we chose Android as the implementation mobile platform giving consideration to the fact that most SNS applications operate on Android and the platform is easily embedded into small embedded device. Smartphone or tablet PC connected with the proposed bluetooth device is an Android-based device and we designed a form of Android app for the function implementation of the devices. When the audio-text gateway app receives SNS text data, it extracts title and sender information from the message header information in a form of text data and sends them via ACL (Asynchronous Connection-Oriented) link to the bluetooth device showing the data on the screen. Android-based bluetooth devices are not possible to play voice through speaker because the bluetooth hands-free or headset profile ported within Android platform normally only includes audio gateway's function. The proposed bluetooth device application, therefore, applies the streaming scheme that sends data via ACL link instead of the way that sending them via SCO (Synchronous Connection-Oriented) link.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.118-125
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• 2006

Mobile nodes in FHMIPv6 has both advantages of HMIPv6 protocol which reduces signaling delay time and resource consumption during a handover and fast handover algorithm which reduces packet loss. Fast handover algorithm can reduce packet loss by 'tunneling' method ; that transmits a packet from old access router to new access router in case of handover. However, the fast handover algorithm can cause a reordering problem in a receiver between packets tunneled from the previous access router and packets transmitted directly to the new access router, which could degrade the TCP performance due to congestion control. In this paper, we propose two algorithms to solve the reordering problem in fast handover. The first one uses a holding timer for tunneling, the other adds a new algorithm to routers that adopt snoop protocol. We compare the performance of the proposed reseuquencing algorithms with that of the existing FHMIPv6 protocol by simulation. The simulation results show that the proposed algorithms solve the reordering problems and enhance TCP performance by preventing TCP sender entering congestion control.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.128-138
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• 2010

In this paper, we propose a new bit assignment scheme for Wyner-Ziv video coding. Distributed video coding (DVC) is a new video coding paradigm which enables greatly low complexity encoding because it does not have any motion prediction module at encoder. Therefore, it is very well suited for many applications such as video communication, video surveillance, extremely low power consumption video coding, and other portable applications. Theoretically, the Wyner-Ziv video coding is proved to achieve the same rate-distortion (RD) performance comparable to that of the joint video coding. However, its RD performance has much gap compared to MC-DCT-based video coding such as H.264/AVC. Moreover, Transform Domain Wyner-Ziv (TDWZ) video coding which is a kind of DVC with transform module has difficulty of exact bit assignment because the entire image is treated as a same message. In this paper, we propose a feasible bit assignment algorithm using adaptive quantization matrix selection for the TDWZ video coding. The proposed method can calculate suitable bit amount for each region using the local characteristics of image. Simulation results show that the proposed method can enhance coding performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.169-177
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• 2007

Existing wireless access (mobile) routers are based commonly on the network address and port translation (NAPT) technique which permits simultaneously sharing a subscriber's connection to the network with multiple users. However, the NAPT architecturally makes the users invisible on the network side, thus becoming a user-oriented connection technique. In this paper, we propose a novel service provider-oriented unlicensed nomadic access relay station (WiNNERS) for helping wireless broadband network service providers to make their business more lucrative by accommdating unlicensed band users as subscribers into their network. The WiNNERS offers service providers the capability to directly manage each of the unlicensed band users at the network side. This direct management allows the service providers to flexibly and simply handle QoS, access control, and billing for each user. In order to distinguish each of the unlicensed band users the WiNNERS constructs a virtual tunnel from each user's terminal to the network access router using connection identifiers which is defined for service flow management within the WiBro system, Consequently, our proposed service provider-oriented relay station can be included into the WiBro network system with minimum modifications.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.153-163
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• 2011

Smartphone is a mobile device which can perform better than feature phone. Recently, growth in demand for advanced mobile devices boasting powerful performance, market share of smartphone is increasing rapidly in mobile device market, for example, iphone and android phone. Smartphone can provide many functionalities, e-mail, scheduler, word-processing, 3D-game, and etc, based on its powerful performance. Thus, various secret information is integrated in smartphone. To provide service, sometimes, smartphone transmits informations to outside via wireless network. Because smartphone is a mobile device, user can lose his/her smartphone, easily, and losing smartphone can cause serious security threats, because of integrated information in smartphone. Also data which is transmitted in wireless network can be protected for privacy. Thus, in present, it is very important to keep secure smartphone. In this paper, we analyze threats and vulnerabilities of smartphone based on its environments and describe countermeasures against threats and vulnerabilities.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.1-12
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• 2010

The existing survey of the actual use relevant transportation, implemented in order to reflect transportation policy, has been performed for users by researcher directly, or thereby analysing the data of particular date-oriented of transportation card business's content so that such method have many problems. To solve such problem, we developed a new system, Interoperable Traffic Information Collection System which include several functions of effective collecting of transportation use-data created from the Nation-wide Interoperable Transportation System, accurate counting and easy inquiry. This system consists of Link-server to collect and count for transportation use-data, DB-server to store for this data and Inquiry terminal to search for the information needed. To verify for developed this system, we run test-bed by connection between this system and the Nation-wide Interoperable Transportation System developed by the KOREA Financial Telecommunications & Clearings, the KORAIL NETWORKS and the HiPlusCard. And through result of test-bed, we proved that Interoperable Traffic Information Collection System practically works well. Thus we can look for systematic reflect of reliable information.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.22-32
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• 2010

Increasingly advanced Information Technology (IT) has changed the operator so as to create more diversified and advanced traffic information demand. To deal with the changing demand in private sector, a concept of on-demand traffic information has been rapidly introduced. However VMS, a product of the first generation of ITS, which was designed to provide the unspecified individuals during driving the car with the basic level of traffic information by the public failed to actively change itself in such a changing pattern. This study was intended to describe the VMS system (tentatively, FM-VMS) which was further developed to accommodate the needs favoring the sophisticated PDA with the public role of providing the unspecified individuals with the equal information. FM-VMS introduced in this study is the device designed to transmit the voice and message to the drivers through the radio information device mounted on a car. A core technology is, unlike FM-DARC and RDS, the Water Making technology which directly inserts the digital signal into FM frequency in use. It's been currently used for broadcasting and security purpose. A detection rate as a result of testing FM-VMS system using Water Making technology was 90% or more in voice and message within 20m from test VMS. When a public-developed VMS information could be transmitted using FM frequency to the relatively vulnerable users (vulnerable to traffic information) in voice on a real-time basis to provide the regional traffic information, and furthermore, VMS message could be received through radio liquid using FM frequency only, it would obviously bring about the innovation in ITS as well as pave the way for creating the new added value down the road.