• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.3
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• pp.592-606
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• 2011

Currently, the development of multimedia communication has progressed so rapidly that the video program service has become a requirement for ordinary customers. The quality of experience (QoE) for the visual signal is of the fundamental importance for numerous image and video processing applications, where the goal of video quality assessment (VQA) is to automatically measure the quality of the visual signal in agreement with the human judgment of the video quality. Considering the codec effect to the video quality, in this paper an efficient non-reference (NR) VQA algorithm is proposed which estimates the video quality (VQ) only by utilizing the distorted video signal at the destination. The VQA feature vectors (FVs) which have high relationships with the subjective quality of the distorted video are investigated, and a hybrid NR VQA (HNRVQA) function is established by considering the multiple FVs. The simulation results, testing on the SDTV programming provided by VCEG Phase I, show that the proposed algorithm can represent the VQ accurately, and it can be used to replace the subjective VQA to measure the quality of the video signal automatically at the destinations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.16-24
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• 2010

High Speed Uplink Packet Access(HSUPA) is a WCDMA Release 6 technology which corresponds to High Speed Downlink Packet Access(HSDPA). Node B Supports fast scheduling, Hybrid ARQ(HARQ), short Transmission Time Interval(TTI) for high rate uplink packet data. It is very important to detect Iub congestion to improve end user's Quality of Service(QoS). This paper proposes Node B Congestion Detection(BCD) mechanism and suggests to use the hybrid of Transport Network Layer(TNL) congestion detection and BCD. It is shown that HSUPA user throughput performance can be improved by the proposed method even with small Iub bandwidth.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.26-27
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• 2015

본 논문은 ATSC2.0 기반 8-VSB/MH 융합형 3DTV (A/104 Part 5 Service Compatible 3DTV using Main and Mobile Hybrid Delivery) 방식 수신모듈개발에 대한 내용을 기술한다. ATSC A/104 Part 5 SC-MMH 3DTV 방식은 2014. 8 월 미국의 지상파 DTV 표준화 논의단체인 ATSC 에서는 고정 HD 서비스를 위한 8-VSB 채널과, In-band 모바일 TV 서비스를 위한 ATSC M/H 채널을 이용하여, 주파수 효율을 극대화한 새로운 방식의 고정/이동 TV 융합형 3DTV 방식을 ATSC 3DTV Standard 로 채택되었으며, 2015 년말까지 좌/우영상의 화질차이 극복을 위한 화질개선안(Video Enhancement Information) 역시 ATSC 국제표준채택이 유력하다. 본 논문에서는 이와 같은 8-VSB/MH 융합형 수신기 개발에 필수적으로 필요한 8-VSB/MH 융합형 수신모듈 구현에 대한 내용을 기술한다.

• ETRI Journal
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• v.38 no.1
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• pp.18-29
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• 2016

In this paper, we discuss the issues of providing protection for point-to-multipoint connections in both Ethernet and MPLS-TP-based packet transport networks. We introduce two types of per-leaf protection-linear and ring. Neither of the two types requires that modifications to existing standards be made. Their performances can be improved by a collective signal fail mechanism proposed in this paper. In addition, two schemes - tree protection and hybrid protection - are newly proposed to reduce the service recovery time when a single failure leads to multiple signal fail events, which in turn places a significant amount of processing burden upon a root node. The behavior of the tree protection protocol is designed with minimal modifications to existing standards. The hybrid protection scheme is devised to maximize the benefits of per-leaf protection and tree protection. To observe how well each scheme achieves an efficient traffic recovery, we evaluate their performances using a test bed as well as computer simulation based on the formulae found in this paper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7B
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• pp.565-577
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• 2012

Recently, cable operators are providing broadcast and IP based services using Hybrid Fiber Coaxial(HFC) networks while securing frequency band for video contents and convergence services are becoming an important issue. But, HFC networks have difficulty of securing frequency band, because they are used for broadcasting service based on MPEG. Therefore, it is necessary to find out a method to go broadband. Radio Frequency over Glass(RFoG), one of the methods to go broadband, is advantageous in the sense that it can overcome bandwidth limit and simplifies the structure. In this paper, we find characteristic and standard of RFoG and services. And we also find advantage of RFoG by evaluating performance.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.237-241
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• 2008

Femtocells are cellular access points that connect to a mobile operator's network using residential DSL or cable broadband connections. They have been developed to work with a range of different cellular standards including CDMA, GSM and UMTS. Like legacy base station, the frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. So, some techniques are discussed to alternate with the legacy GPS system. NTP, PTP, Synchronous Ethernet use the ethernet to synchronize distributed clocks in packet networks. AGPS support reliable position information than the legacy GPS in poor signal conditions. But, These method also have some problems. So, hybrid timing method like A-GPS+PTP and TV+GPS was developed to make up the weak point of GPS. This paper introduces the each method and compare each other and y propose much better solution for timing synchronization at the Femtocell

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1076-1081
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• 2007

In this paper, we propose a new switch structure for time division duplex(TDD) system. The existing TDD structure utilizes a circulator fur isolation characteristic between ports. However, the circulator produces intermodulation distortion signals which are undesired signal because of its nonlinear properties. The proposed circuit is composed of a modified branch-line hybrid coupler which controls the signal flow while the isolated port is open-/short- terminated. In order to prove the validity of the presented structure, the switch circuit is fabricated and measured at 2.3GHz, the center frequency of Wibro service system.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.384-387
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• 2003

In this paper, we have designed the integrated wire and wireless P2P framework using mobile agents to share efficiently resources as media file. Most of the P2P applications are used on the wire network. We propose the integrated wire and wireless P2P framework. Proposed P2P platform is based on JXTA of Sun Microsystems. But JXTA is pure peer-to-peer network model, so it sends message other peers as broadcast style to request resources. In this way, there are some problems as massage overload, bandwidth loss, etc. In order to solve this problem, we propose a hybrid peer-to-peer network model using mobile agent. Proposed scheme also solve existing hybrid pEp model's flaws which have the delay and low rate due to concentrated server. In proposed scheme, mobile agents that have autonomy and mobility are used to search the location of resources. Besides, mobile agents could solve the loss problem of the search result. To improve P2P QoS(Quality of Service), we could monitor peer's state information using PIP(Peer Information Protocol) of JXTA.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.2
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• pp.102-106
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• 2011

The transfer capability of HFC (Hybrid Fiber Coax) network is superior to xDSL. HFC network, however, is not suitable for transferring high quality video due to cable model interfaces. For the services of high quality IPIV or VOD, the extra exclusive downstream transfer system is required without upgrading pre-equipped cable modem and service capability. This paper is aimed to develop the extra exclusive downstream transfer system not changing existing cable modem system but providing same quality of services. This system is composed of the extra exclusive downstream IP-cable sender and modem. This sender and modem have 30 Mbps transfer capability and HDTV stream can be served in the Cable TV network using 21 Mbps HDTV transport stream.

• Journal of IKEEE
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• v.22 no.4
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• pp.1147-1151
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• 2018

As personal users create and share lots of contents at any time and any places, new networking architecture such as content centric networking (CCN) has emerged. CCN utilizes content name as a packet identifier, not address. However, current CCN has a limitation for content source mobility management. The movement of content sources cause long delivery latency and long service disruption. To solve that, a hierarchical mobility management was was proposed. However, the hierarchical mobility management scheme has still the loss of interest packets and long handoff latency. So, this paper presents the hybrid hierarchical mobility management in mobile CCN environements to reduce both the loss rate of interest packets and the handoff latency. It is shown from the performance evaluations shows that the proposed scheme provides low loss rate of control message.