• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.173-178
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• 2006

In this paper, a channel estimation based on the time-domain windowing and its imperfectness in OFDM-based multiple-antenna transmission systems are analyzed with an emphasis on a preamble design for multi-channel separation, From the computer simulation results, the OFDM-CDMA system applying a space-time-frequency diversity with a full-rate full diversity code can give the diversity of D = 4 and D = 8 for both multi-user cases of maximum user and half user capacities, respectively

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3028-3039
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• 2015

Recently, the web index of Korea peaked at the top 10 among the eighty six countries, and Korea became the only Asian country ranked at the top level. Korea also has been on the top in the field of Internet penetration rate, in terms of both high-speed broadband and wireless Internet. However, such achievements did not guarantee the national level for the effective use of information utilizing Internet. According to OECD, the national informatization index of Korea has not been free from the middle of the OECD countries. Despite of the heightened pressure in practically enhancing effective information use utilizing Internet, the previous research interests and efforts to develop the Internet-related framework or to identify Internet capabilities rarely existed. The study aims to propose the framework, named "Internet Information Orientation" that illustrates the relationship between Internet capabilities and national competitiveness on Internet. The research identified the specific Internet capabilities, reclassified the capabilities based on the research issues provided at the 6^th international conference on Internet held in December 2014, and finally described the rigorous research endeavors on the issues. As a result, 16 papers presented and selected as the outstanding papers at the conference handle issues to be brought together, which include: Wireless Network, Internet of Things, Green Computing, Multimedia Processing, Big Data and Text Mining, Database in Cloud Environment, Business Intelligence, Software Engineering, IT Strategy & Policy, and Social Network Services.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.1
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• pp.17-23
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• 2007

The home network has been revitalized due to the emergence of the high-speed broadband network and explosive increases of the home network services. Especially multicast based high-definition (HD) IPTV service is on high demand from both Internet service provider (ISP) and users. In order to provide high quality HD IPTV service without packet loss and delay, the ISP utilizes various network QoS mechanisms. Due to the misleading fact, that the home gateway is considered as an end terminal in terms of the ISP's viewpoint, the ISPs can not guarantee the end-to-end QoS within the scope of the current home network architecture. Therefore, an independent QoS guaranteed mechanism should be considered within the home network domain. As the home gateway manages both private home and public access network within the home network, we propose and implement a novel QoS mechanism for the multicast based HD IPTV service over the home gateway. In order to provide QoS guaranteed HD IPTV service, the proposed mechanism classifies the packets, manages home network bandwidth resources, and executes call admission control using the channel join message. Also, we utilize layer 2 multicast packet forwarding scheme to improve the overall performance of the home network services. Through the experiments of implementing the multicast based HD IPTV services, we will verify the efficiency of the proposed mechanism.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.8-15
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• 2022

The new 5G radio technology (NR) can provide ultra-reliable low latency communications. The supporting 5G network infrastructure will move away from the previous point-to-point network architecture to a service-based architecture. 5G can provide three new things, i.e., wider channels, lower latency and more bandwidth. These will allow 5G to support three main types of connected services, including enhanced mobile broadband, mission-critical communications, and the massive Internet of Things (IoT). In 2015, the 5th generation (5G) mobile communication was officially approved by the International Telecommunication Union (ITU) as IMT-2020. Since then, 3GPP, the international organization responsible for 5G standards, is actively developing specifications for 5G technologies. 3GPP Release 15 provides the first full set of 5G standards, and the evolution and expansion of 5G are now being standardized in Release 16 and 17, respectively. This paper provides an overview of 3GPP 5G technologies and key services.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.213-219
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• 2017

Recently, the Internet Protocol Television (IPTV) services have become very common, enabling various Internet-based services as well as watching TV. In the IPTV system, a Set-Top box (STB) plays a key role as a network terminal device that transmits and receives realtime multimedia contents. In addition, the IPTV networks are usually supported by broadband optical fiber-base network such as fiber-to-the-home (FTTH), However, a general IPTV STB is regarded as one of the local area network (LAN)-attached devices while sharing the bandwidth of the LAN (e.g., Ethernet). In order to overcome the limited bandwidth utilization by fully facilitating the broadband bandwidth (e.g., 1 Gbps) of the optical fiber-based network, we propose a new FC (Fiber Channel)-embedded IPTV STB which can be directly attached to the optical fiber network. Then, we verify that the impacts of the proposed FC-embedded IPTV STB by organizing the the FC-AL (Fiber Channel-Arbitration Loop) network equipped with the FC-embedded IPTV We measures the average Start-up Delay, Average Reject Ratio and the Number of Concurrent Users through extensive simulations to investigate the performances of the suggested FC-AL-based IPTV network. Surprisingly, the IPTV network architecture with the proposed FC-embedded IPTV STBs has an excellent average start-up delay of less than 10 msec, an acceptable average reject ratio of less than 3 % as well as a linear increase of the number of concurrent users when extending the architecture. This reveals that the proposed FC embedded STB has a superior impacts on the performance of the entire IPTV network by effectively utilizing the broadband bandwidth of the fiber optic-based network.

• Journal of Korea Technology Innovation Society
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• v.4 no.3
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• pp.342-354
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• 2001

The appearance of on-demand business model of multimedia contents is one of the biggest changes in the broadband Internet which aims at the high-speed Internet users. Currently the interest in the webcasting service, a new converged service of the broadcasting and the telecommunications, has been increased. However the quality of service is not guaranteed due to the bottleneck problem in a middle-mile as the fundamental limit of the Internet, and has not been improved greatly due to the small-scaled operators of the webcasting services. This study suggests a new business model of the multi-channel satellite webcasting service based on the satellite multicasting and content delivery network, which guarantees the quality of service and channelizes the contents by the type or by the special purpose.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.86-89
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• 2002

Recently, video conferencing, Web-casting service, and network sane service which use multicast-based service are popular in Internet. In order to support the broadband Internet services efficiently, more communication bandwidth are needed. The WDM single-hop broadcast network topology is coming into the spotlight in next-generation access networks area. In this paper, the new multicast scheduling algorithm, PGM, is proposed and is evaluated through the computer simulation. The PGM method shows the better performance comparing with existing multicast scheduling algorithm.

• Information and Communications Magazine
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• v.32 no.9
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• pp.17-23
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• 2015

This paper presents design methodologies for 5G architecture ensuring lower latency than 4G/LTE. Among various types of 5G use cases discussed in standardization bodies, we believe mobile broadband, massive IoT(Internet of Things) and mission-critical IoT will be the main 5G use cases. In particular, a mission-critical IoT service such as remote controlled machines and connected cars is regarded as one of the most distinguished use cases, and it is indispensable for underlying networks to support sufficiently low latency to support them. We identify three main strategic directions for end-to-end network latency reduction, namely new radio access technologies, distributed/flat network architecture, and intelligent end-to-end network orchestration.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.113-118
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• 2017

As interest in mobile devices and networks has increased recently, voice over internet protocol (VoIP) service, which is a technology for transmitting voice data using an existing internet protocol (IP) network, has rapidly spread, Cheap voice call service has become possible. As the digital broadcasting service becomes popular, hybrid fiber coaxial (HFC) network technology, which uses broadband cable network through fusion of broadcasting and communication, utilizes existing communication system and network equipment to provide various new services such as interactive broadcasting service. Therefore, if UGS-AD is applied to VoCM and RTPS is applied to MTA in order to guarantee the quality of voice data in actual HFC Internet service network, it is possible to smoothly perform voice data transmission in narrow upstream band which is a problem in actual commercial HFC network We also proposed a method to improve VoIP service by improving QoS of voice data in HFC Internet service network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1101-1112
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• 2006

With the recent growth in demand for high-data rate multimedia services in the wireless environments, the Mobile Broadband Wireless Access (MBWA) technologies, such as WiBro (Wireless Broadband internet) system, are gradually coming into the spotlight. Unlike the conventional mobile communication networks based on cellular system, the WiBro system basically consists of IP based backbone networks that will be ultimately deployed by Ipv6 (IP version six) based backbone networks according to the All-IP trend for the network evolution. In such wireless mobile environments, it is needed to support the mobility management protocol on network layer as well as physical layer and Medium Access Control (MAC) layer in WiBro system. Accordingly, in this paper, we propose a fast handover scheme for improving the handover performance in IPv6 based WiBro system and show that the proposed scheme achieves loss-free and low handover latency during inter-subnet movement of the mobile stations through the simulation.