• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.287-290
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• 2003

In recent years, one of the main trends of GIS is to construct and provide realistic and human-perceptible information of spatial object using video data. The rapid progress of wireless mobile technology makes the multimedia source using video data possible on mobile environment. Instead of traditional map-based service, video-based location services, that provide video data as location context, would be of interest in connection with various mobile applications requiring location service, such as telematics, LBS, etc. In this paper, we present the location service system using geo-referenced video on wireless mobile environment.

• International Journal of Contents
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• 제14권4호
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• pp.30-38
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• 2018

Recently, HTTP Adaptive Streaming(HAS), a video streaming service over the HTTP based web platform has become common. The use of HAS service in mobile communication devices such as mobile phones and tablet PCs is rapidly expanding. This paper addresses ways to improve the quality of HAS service by enhancing the terms of viewer satisfaction. HAS systems have several internal operational processes, which can affect viewer satisfaction. Such processes include, the quality determination for the next video chunk, the TCP connections-setup procedure and the congestion control operation of the TCP. This paper proposes a transmission scheme to improve the HAS quality services over mobile web. The proposed scheme takes into consideration the past implicit communication state of the receiver's playback buffer occupancy. The results of these experiments indicate that the proposed scheme can improve the quality of HAS service from the mobile viewer's point of view.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.4068-4086
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• 2014

Due to the prevalence of powerful mobile terminals and the rapid advancements in wireless communication technologies, the wireless video streaming service has become increasingly more popular. Recent studies show that video streaming services via Transmission Control Protocol (TCP) are becoming more practical. TCP has more advantages than User Diagram Protocol (UDP), including firewall traversal, bandwidth fairness, and reliability. However, each video service shares an equal portion of the limited bandwidth because of the fair sharing characteristics inherent in TCP and this bandwidth fair sharing cannot always guarantee the video quality for each user. To solve this challenging problem, an Adaptive Multiple TCP (AM-TCP) scheme is proposed in this paper to guarantee the video quality for mobile devices in wireless networks. AM-TCP adaptively controls the number of TCP connections according to the video Rate Distortion (RD) characteristics of each stream and network status. The proposed scheme can minimize the total distortion of all participating video streams and maximize the service quality by guaranteeing the quality of each video streaming session. The simulation results show that the proposed scheme can significantly improve the quality of video streaming in wireless networks.

• 한국전자통신학회논문지
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• 제14권2호
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• pp.331-338
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• 2019

인터넷을 통한 영상 서비스의 비중이 점점 높아지고 있다. 인터넷을 통한 스트리밍 형태로 제공되는 영상서비스는 전송 과정에서 품질이 저하될 수 있기 때문에 품질 평가 및 관리가 매우 중요하다. 현재 영상 서비스에 대한 품질 관리는 특정 파라미터들의 측정값에 기초한 객관적 방법이 널리 사용되고 있다. 그러나 영상 서비스의 품질은 사람이 체감하는 품질이기 때문에 본질적으로 주관적인 측정이 더 이상적이라 할 수 있다. 따라서 본 논문에서는 모바일 환경에서 주관적 방법이 가지는 한계점을 극복할 수 있는 영상 서비스 품질 관리 방안을 제안하고 이를 위한 시스템을 설계한다. 제안하는 방법은 향후 모바일 환경에서 영상 서비스를 보다 효율적으로 관리할 수 있는데 기여할 것으로 기대된다.

• 방송공학회논문지
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• 제13권1호
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• pp.25-33
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• 2008

영상통화는 3G 이동통신망에서 가장 대표적인 서비스이며, 많은 여러 분야에서 영상통화의 품질을 향상시키기 위한 노력이 있다. 국내에서도 SKT와 KTF에서 3G와 3.5G망으로 WCDMA 방식을 채택해 전국서비스를 시작하였고, 이미 백만 명 이상의 많은 사용자를 확보한 상태이다. 본 논문에서는 WCDMA 망에서의 영상통화방법에 대해 알아보고, 영상품질을 향상시키기 위해 회선망의 물리계층 정보를 이용하여 영상코덱에서 손실확산을 최소화 할 수 있는 슬라이스 그룹을 만드는 새로운 전송기법에 대해 제안하고 실험을 통해 성능을 평가해 보았다. 실험결과, 기존의 방법들보다 좀 더 회선 망과 영상코덱 사이의 동기화가 잘 이루어지고, 이를 통해 손실의 확산을 줄일 수 있는 결과를 보여준다.

• 한국콘텐츠학회논문지
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• 제18권8호
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• pp.434-445
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• 2018

본 연구는 닐슨-코리안클릭사의 3 screen data를 이용하여 모바일 OTT 동영상 서비스 이용이 홈 TV 시청을 대체하는지 여부를 실증 분석하였다. 분석결과 모바일 OTT 동영상 서비스의 이용시간이 1% p 증가하면 홈 TV 시청시간이 12.4% 감소하는 것으로 나타났으며, 유튜브나 통신 3사가 제공하는 OTT 동영상 서비스(Oksusu, Alleh TV, 비디오포털)의 이용시간이 1%p 늘어나면 지상파 채널 시청시간이 각각 16.2%와 23.9% 감소하는 것으로 추정되었다. 향후 모바일 OTT 동영상 서비스의 홈 TV 대체 양상은 더욱 가속화될 것으로 보인다. 유료방송 산업과의 규제 형평성 논란을 해소하고 시청자 권익을 보호하기 위하여 OTT 동영상 서비스에 대한 규제 범위와 수준에 관한 논의가 보다 신속히 이루어져야 할 것이다. 사업자 측면에서는 콘텐츠의 차별화뿐만 아니라 다양한 결합상품을 제공하는 등 요금제의 다양화 전략이 필요하다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2118-2135
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• 2012

With the rapid development of heterogeneous emerging wireless technologies and numerous types of mobile devices, the need to support robust mobile video streaming based on the seamless handover in Future Internet is growing. To support the seamless handover, several IP-based mobility management protocols such as Mobile IPv6 (MIPv6), fast handover for the MIPv6 (FMIPv6), Hierarchical MIPv6 (HMIPv6) and Proxy Mobile IPv6 (PMIPv6) were developed. However, MIPv6 depreciates the Quality-of-Service (QoS) and FMIPv6 is not robust for the video services in heterogeneous emerging wireless networks when the Mobile Node (MN) may move to another visited network in contrast with its anticipation. In Future Internet, the possibility of mobile video service failure is more increased because mobile users consisting of multiple wireless network interfaces (WNICs) can frequently change the access networks according to their mobility in heterogeneous wireless access networks such as 3Generation (3G), Wireless Fidelity (Wi-Fi), Worldwide Interoperability for Microwave Access (WiMax) and Bluetooth co-existed. And in this environment, seamless mobility is coupled according to user preferences, enabling mobile users to be "Always Best Connected" (ABC) so that Quality of Experience is optimised and maintained. Even though HMIPv6 and PMIPv6 are proposed for the location management, handover latency enhancement, they still have limit of local mobility region. In this paper, we propose a robust mobile video streaming in Heterogeneous Emerging Wireless Systems. In the proposed scheme, the MN selects the best-according to an appropriate metric-wireless technology for a robust video streaming service among all wireless technologies by reducing the handover latency and initiation time when handover may fail. Through performance evaluation, we show that our scheme provides more robust mechanism than other schemes.

• 방송공학회논문지
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• 제13권5호
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• pp.586-595
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• 2008

본 논문에서는 이동 환경에서 다시점 비디오를 제공하는 적응형 다시점 비디오 서비스 프레임워크를 제안한다. 중간시점 영상의 실시간 생성과 다시점 비디오의 클라이언트 적응을 통해 이동 환경이 갖는 성능 제약을 해결한다. 그리고 적응 변환 작업을 서버에서 수행함으로써 클라이언트의 부하를 줄이고, H.264/AVC를 채택하여 비디오의 압축 효율을 개선한다. 이를 위해, 멀티미디어 프레임워크 표준인 MPEG-21 DIA (Digital Item Adaptation)를 참조하여, 사용자 요구와 클라이언트 기기의 특성에 맞도록 비디오를 적응시키는 이동 환경을 위한 새로운 다시점 비디오 DIA를 구현한다. 제안 프레임워크의 효율성과 성능을 측정한 결과, 다시점 비디오의 이동 서비스는 양방향으로 해상도가 $320{\times}240$이면, 최대 초당 13 프레임까지 가능하고, 기존 3D 점의 투영 방법과 비교하여 5배 빠른 중간시점 영상을 생성한다.

• Journal of Information Technology Applications and Management
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• 제17권1호
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• pp.107-125
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• 2010

The purpose of this research is to identify the critical factors influencing on the continuous use of video telephony service for mobile devices. An empirical analysis has been performed by using service quality, brand image, price, fun as influencing factors, and satisfaction and commitment as mediating factors. The partial least squares(PLS) methodology with 228 questionnaires has been conducted. The results indicated that brand image, price, and fun were mediated by satisfaction and commitment to have a statistically significant influence on continuous use of video telephony service. Service quality showed a significant effect on continuous use mediated by satisfaction while it did not show any influence through commitment. Based on the results, companies in the communication service industry should consider and focus on the improved brand image, appropriate fees, and individual preferences for fun for the successful marketing activities, and should also maintain amicable relations with their customers.

• 대한임베디드공학회논문지
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• 제10권4호
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• pp.241-255
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• 2015

Recent network environment has been rapidly evolved to cloud computing environment based on the development of the Internet technologies. Furthermore there is an increasing demand on mobile cloud computing due to explosive growth of smart devices and wide deployment of LTE-based cellular networks. Thus mobile Desktop-as-a-Service(DaaS) could be a pervasive service for nomadic users. In addition, video streaming traffic is currently more than two-thirds of mobile traffic and ever increasing. All such trends enable that video streaming in mobile DaaS could be an important concern for mobile cloud computing. It should be noted that the performance of the Transmission Control Protocol(TCP) on cloud host servers greatly affects Quality of Service(QoS) of video streams for mobile users. With widely deployed Linux server platforms for cloud computing, in this paper, we conduct an experimental analysis of the twelve Linux TCP variants in mobile DaaS environments. The results of our experiments show that the TCP Illinois outperforms the other TCP variants in terms of wide range of packet loss rate and propagation delay over LTE-based wireless links between cloud servers and mobile devices, even though TCP CUBIC is usually used in default in the current Linux systems.