• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.117-125
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• 2003

IPv6 (IP version 6), which was standardized by the IETF (Internet Engineering Task Force) to cope with existing IPv4 problems, needs several approaches for interoperation with IPv4. The internetworking of IPv6 with IPv4 is an important key to the deployment of the next generation Internet. As the solutions to the transition mechanism, both tunneling and translator methods have been proposed. In this paper, we analyze functional elements for implementation design of a transition mechanism based on the NAT-PT (NAT-Protocol Translation), and propose an extension algorithm that uses ports for effective use of global IPv4 addresses. The algorithm presented in this paper is a method of combining NAT-PT with Port Translation mechanism. The algorithm does not assign an IPv4 address to the host that needs IPv4 address, but allocates a single temporary IPv4 address and a port number in order to identify host.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.793-796
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• 2013

스마트폰, IPTV(Internet Protocol Television), VoIP(Voice over Internet Protocol) 등의 인터넷을 활용한 서비스의 증가는 IPv4(Internet Protocol Version4)의 주소 부족문제를 야기시켰으며 이를 해결하기 위한 장기적인 해결방안으로는 IPv6(Internet Protocol Version6)가 제시되었고 단기적으로는 NAT(Network Address Translator)가 제안되었다. NAT는 사설 IP 주소를 공인 IP 주소로 활용하여 네트워크에 접속할 수 있도록 지원하며 주소 부족 문제를 해결하고 내부 네트워크를 보호하는 긍정적인 기능도 하지만 역으로 해커들에게 숨은 공간을 제공하는 역할을 하기도 한다. 본 논문에서는 NAT 기능을 활용한 IP 공유기를 통해 내부 보안 프로세스를 우회할 수 있는 단말기를 검출하는 탐색 알고리즘을 분석하고 이를 병렬화하여 정확도를 높일 수 있는 검출 시스템을 연구하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.229-233
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• 2007

VoIP(Voice over Internet Protocol)란 음성 데이터를 IP 데이터그램 방식으로 기존 인터넷망을 통해 전달해 주는 기술을 말한다. 기존 인터넷망을 이용하여 음성 데이터를 전달해 줌으로써 기존의 음성 전화 서비스에서 사용되던 회선비용을 크게 절감할 수 있다는 점은 VoIP의 장점 중 하나이다. 그런데 VoIP를 기존의 인터넷망에 그대로 적용하기에는 VoIP에서 사용되는 프로토콜의 특성으로 인해 어려움이 따르게 된다. 즉, 기존의 인터넷망에서 사용되고 있는 방화벽과 NAT(Network Address Translator)장비는 보안을 위해서는 필수적인 요소들 이지만, VoIP의 통신 입장에서는 음성 데이터의 원활한 통신을 방해하는 요소로 작용을 하게 된다. 이러한 문제는 VoIP 통신에 사용되는 시그널링 프로토콜인 H.323과 SIP 프로토콜의 연결 설정과 데이터 전송에 사용되는 동작 방식이 방화벽과 NAT장비의 기능에 충돌하는 점 때문에 발생하게 된다. 따라서 기존의 인터넷망을 그대로 사용하면서 VoIP의 통신이 원활하게 이루어지도록 하기 위해서는 이러한 문제의 해결이 반드시 이루어져야 한다. 본 논문에서는 기존에 Firewall/NAT Traversal 문제 해결을 위해 연구되던 기법들에 대해 살펴보고, 새로운 구조를 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.493-496
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• 2002

홈 네트워크의 문제점인 IP 부족 문제와 부가 서비스(디지털 컨텐츠의 지능형 서비스, 서비스 번들 지원 등) 제공의 한계성을 극복하기 위해 Service Server for Residential Gateway(SSRG)를 제안한다. SSRG는 단독주택뿐만 아니라 대규모 아파트 단지 혹은 주택단지에 개별적으로 설치된 RG를 통합 관리하는 서버로서 홈 네트워크 및 내부 네트워크에 로컬 IP를 부여하고 RG와 SSRG를 NAT(Network Address Translator)를 통하여 제어함으로써 P의 문제를 해결함과 동시에 각 홈 네트워크와 RG의 기능을 확대하고 보다 많은 부가 서비스를 제공할 수 있도록 구현하였다. 제안된 SSRG는 가정 내에 보다 확장된 서비스와 기기 관리를 위한 통로 제공, RG 및 각종 기기들의 소프트웨어 업그레이드 및 기기 상태점검이 가능하고, 또한 사설 IP 상에서도 기기들을 외부에서 액세스 할 수 있고 각종 서버를 하나의 단지 혹은 논리적으로 구분되는 하나의 서브 넷에 두게 됨으로써 관리 및 향후 보수가 용이한 장점이 있다.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.335-347
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• 2007

VoIP (Voice over IP) is a technology to transport video and voice traffic over IP networks such as Internet. Today, the VoIP technology is viewed as the right choice for providing voice, video, and data communication among various terminals over the next generation network. This paper discusses a multipoint VoIP implementation with end-point mixing model which can support multipoint conference without a conference bridge. The multipoint VoIP is implemented with SIP (Session Initiation Protocol), and supports STUN (Simple Traversal of UDP Through NATs) since it works in an asymmetric NAT (Network Address Translator) environment. The characteristics of this paper are as follows. It is possible that all terminals in the hierarchical conference don't receive the duplicated media information because we use the end-point mixing model with the new media processing module. And, the paper solves the problem that the hierarchical conference session should be separated into several sessions when a mixing terminal terminates the hierarchical conference session.

• Journal of Internet Computing and Services
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• v.15 no.3
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• pp.45-52
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• 2014

The Ubiquitous-City (U-City) is a smart or intelligent city to satisfy human beings' desire to enjoy IT services with any device, anytime, anywhere. It is a future city model based on Internet of everything or things (IoE or IoT). It includes a lot of video cameras which are networked together. The networked video cameras support a lot of U-City services as one of the main input data together with sensors. They generate huge amount of video information, real big data for the U-City all the time. It is usually required that the U-City manipulates the big data in real-time. And it is not easy at all. Also, many times, it is required that the accumulated video data are analyzed to detect an event or find a figure among them. It requires a lot of computational power and usually takes a lot of time. Currently we can find researches which try to reduce the processing time of the big video data. Cloud computing can be a good solution to address this matter. There are many cloud computing methodologies which can be used to address the matter. MapReduce is an interesting and attractive methodology for it. It has many advantages and is getting popularity in many areas. Video cameras evolve day by day so that the resolution improves sharply. It leads to the exponential growth of the produced data by the networked video cameras. We are coping with real big data when we have to deal with video image data which are produced by the good quality video cameras. A video surveillance system was not useful until we find the cloud computing. But it is now being widely spread in U-Cities since we find some useful methodologies. Video data are unstructured data thus it is not easy to find a good research result of analyzing the data with MapReduce. This paper presents an analyzing system for the video surveillance system, which is a cloud-computing based video data management system. It is easy to deploy, flexible and reliable. It consists of the video manager, the video monitors, the storage for the video images, the storage client and streaming IN component. The "video monitor" for the video images consists of "video translater" and "protocol manager". The "storage" contains MapReduce analyzer. All components were designed according to the functional requirement of video surveillance system. The "streaming IN" component receives the video data from the networked video cameras and delivers them to the "storage client". It also manages the bottleneck of the network to smooth the data stream. The "storage client" receives the video data from the "streaming IN" component and stores them to the storage. It also helps other components to access the storage. The "video monitor" component transfers the video data by smoothly streaming and manages the protocol. The "video translator" sub-component enables users to manage the resolution, the codec and the frame rate of the video image. The "protocol" sub-component manages the Real Time Streaming Protocol (RTSP) and Real Time Messaging Protocol (RTMP). We use Hadoop Distributed File System(HDFS) for the storage of cloud computing. Hadoop stores the data in HDFS and provides the platform that can process data with simple MapReduce programming model. We suggest our own methodology to analyze the video images using MapReduce in this paper. That is, the workflow of video analysis is presented and detailed explanation is given in this paper. The performance evaluation was experiment and we found that our proposed system worked well. The performance evaluation results are presented in this paper with analysis. With our cluster system, we used compressed $1920{\times}1080(FHD)$ resolution video data, H.264 codec and HDFS as video storage. We measured the processing time according to the number of frame per mapper. Tracing the optimal splitting size of input data and the processing time according to the number of node, we found the linearity of the system performance.