• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.58
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• pp.38-49
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• 2006

In order to increase the spectrum efficiency, recently, there is the number of studies for CR technology. For instance, IEEE 802.22 WRAN(Wireless Regional Area Network) WG considered the CR technology as a solution of WRAN system to serve the high speed internet service(1.5 Mbps down stream and 384 kbps up stream) in 100 km overall coverage and 54 MHz-746 MHz band. Basically, in MAC point of view, the WRAN system have been standardizing based on the IEEE 802.16 MAC layer features such as Data transmission method, QoS provision and Bandwidth request schemes. Additionally, the WRAN system further include CR nature functions such as incumbent user protection, self coexistence which would be importantly considered. Also, the inherent WRAN functions are added such as channel bonding and fractional bandwidth usage. This paper mainly explained frame structure, IU protection, self coexistence which are key functions of WRAN system. Finally, in this paper, we expressed a prospect of IEEE 802.22 WRAN standardization.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.246-247
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• 2018

Since the routes within VTS areas include harbour limit of major ports, there are sections where the traffic volume increases and the routes are normally narrow according to the geographical conditions. In the case of ports and VTS areas located on the west coast of Korea, it is affected by strong current due to large tidal differences. In this paper, we propose a method to produce useful information according to the change of navigation environment by analyzing the characteristics of ship's movement according to tidal stream or current. The SVR seaway model, support vector regression, and grid search were conducted in order to extract models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7B
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• pp.628-637
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• 2003

This paper describes a novel multiplexing scheme for delay-sensitive multiple VBR-coded bit streams in live multimedia service offered to high-speed networks. The primary goal of multiplexing in this paper is to keep delay limits of each bit streams and to enhance network resource utilization when they no multiplexed and transmitted over network. For this aim, this paper presents a dynamical control scheme which does not cause violation of any delay constraints to each bit steam. The scheme is based on the assumption that recent behavior of the each bit scream has high correlation with near-term future behavior. Such property is used to make as flat as possible by both temporal averaging on a stream-by-stream and spatial averaging is introduced when multiple VBR-coded bit streams are multiplexed. The effectiveness of the scheme is evaluated by several simulation using an MPEG-coded video trace of Star_wars and it is shown that the proposed scheme can effectively reduce the feat rate md coefficient of variation of the multiplexed transmission rate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.191-193
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• 2012

the existing developed route guidance services for the visually impaired aids for using RFID tags attached to the cane, the extent to which the cover blocks and RF communication was a simple walking guide service. It has a detection range of RFID readers in short, clear obstacles to location, size and shape can not be determined. And the risk of escape routes in case of questions or directions Measures are urgently needed. Today, due to the Smart Device Development convenience to users and offers many benefits. And the Android platform, Client and Server (PC) between the socket stream, using real-time video and voice information, location information by sending a dangerous situation for the visually impaired to take immediate action on the system and 1: N is to implement the service.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.21 no.1
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• pp.5-17
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• 2010

Search engines, web portal sites, online book stores are being the main stream of information network. Library and its catalog has not influenced as the way it had been to the information network any more. Thus, institutions leading the bibliographic network started to pay much attention to the web user service. This article firstly reviewed the development of the bibliographic network, next generation catalog interface and OPAC 2.0, and investigated the case of OCLC in detail. Based on the reviews, this study suggested the development plan of bibliographic network focusing on the web user service in terms of the three strategies. It is hoped that this article will be the basic study for the future of the bibliographic network and the reference for the changes and improvements of libraries and catalog services.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.109-112
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• 2007

Currently was Convergence time of broadcasting and communication with development of information communication technology and internet infra environment. The superhigh speed internet about under using there is IPTV where it provides the broadcasting contents with broadcasting and communication Convergence service. Digital broadcasting it makes various broadcasting in one stream and it transmits, and about under analyzing it uses Channel information which is included in broadcasting and broadcasting information from the terminal. But, IPTV transmits each broadcasting in multicast methods, therefore the possibility of knowing all Channel information and broadcasting information from the terminal it is not there is a problem point. This paper hereupon it searched IPTV broadcasting information from the terminal and in order to support a channel selection from IPTV broadcasting streams SI about under extracting SD&S XML documents it created and it transmits with the distant multicast the system which plan and it embodied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.334-344
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• 2010

Recently, due to the prevalence of various mobile devices and broadband wireless networks, a significant interests and demands for multimedia streaming services over the Internet have been increasing. However, it is difficult to transmit continuous multimedia stream when mobile terminals are moving. Therefore, in order to deploy mobile IPTV service in the broadband wireless network, efficient wireless resource utilization and seamless QoE (Quality of Experience) offers to the users are an important issue. In this paper, we propose a network based adaptive streaming scheme, called MARC (Mobile Adaptive Rate Control), which controls the quality of the video and rate of the video based on the status of the wireless channel. The proposed scheme uses awareness information of the wireless channel status and controls transmitting streaming video which is suitable for the wireless channel status and mobile station location, in order to provide a seamless video playback for mobile environment in addition to improving the quality of a streaming service. The proposed MARC scheme alleviates the discontinuity of video playback and allocates suitable client buffer in broadband wireless network. Simulation results demonstrate the effectiveness of our proposed scheme.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.4 s.22
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• pp.31-39
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• 2002

In this paper, we propose Media CIS system architecture which provides geographical information of geo-features in video sequences by using 3D geographical database and GPS-related data resulted from 4S-Van. We introduce a novel interoperable geographical data service concept, so-called, Virtual World Mapping (VWA) that can map 3D graphic world with real-world video to provide geographical information. Our proposed method can easily retrieve geographical information and attributes to reconstruct 3D virtual space according to certain frame in video sequences. Our proposed system architecture also has an advantage that can provide geographical information service with video stream without any image processing procedures. In addition to, describing the details of our components, we present a Media GIS web service system by using GeoVideo Server, which performs VWM technique.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.144-156
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• 2005

Video streaming over wireless networks is challenging due to node mobility and high channel error rate. In this paper, we propose a multi-source video streaming (MUVIS) system to support high quality video streaming service over IEEE 802.1l-based wireless networks. We begin by collocating a streaming proxy with the wireless access point to help leverage both the media server and peers in the WLAN. By tracking the peer mobility patterns and performing content discovery among peers, we construct a multi-source sender group and stream video using a rate-distortion optimized scheme. We formulate such a multi-source streaming scenario as a combinatorial packet scheduling problem and introduce the concept of asynchronous clocks to decouple the problem into three steps. First, we decide the membership of the multisource sender group based on the mobility pattern tracking, available video content in each peer and the bandwidth each peer allocates to the multi-source streaming service. Then, we select one sender from the sender group in each optimization instance using asynchronous clocks. Finally, we apply the point-to-point rate-distortion optimization framework between the selected sender-receiver pair. In addition, we implement two different caching strategies, simple caching simple fetching (SCSF) and distortion minimized smart caching (DMSC), in the proxy to investigate the effect of caching on the streaming performance. To design more realistic simulation models, we use the empirical results from corporate wireless networks to generate node mobility. Simulation results show that our proposed multi-source streaming scheme has better performance than the traditional server-only streaming scheme and that proxy-based caching can potentially improve video streaming performance.

• Journal of Internet Computing and Services
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• v.8 no.2
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• pp.77-87
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• 2007

A typical VOD service allows that a number of remote clients playback a desired video from a large collection of videos stored in one or more video servers. The main bottleneck for a VOD service is the network bandwidth connecting to the VOD server to the client due to the high bandwidth requirements. Many previous researches have shown that VOD server can be greatly improved through the use of multicast, broadcast, or P2P scheme. Broadcast is one of the most efficient techniques because it can transmit a stream to many users without additional network bandwidth. But the broadcast has long latency time. In order to overcome the drawback, in this paper, we propose P2Prefix broadcast scheme that can solve the service latency time, which is the problem of broadcast scheme, by using P2P caching as well as minimizing the client buffer requirement.