• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.5
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• pp.435-446
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• 2014

Even if it is important to transmit high rate multimedia information without any transmission errors for surveillance systems, it is difficult to achieve error-free transmission due to infra-less adhoc networks. In order to reduce the transmission errors furthermore, additional signal overheads or retransmission of signals should be required, but they may lead to transmission delay. This paper represents a study on low delay and adaptive video transmission for the unmanned surveillance systems by developing system protocols. In addition, we introduce an efficient and adaptive control algorithm using system parameters for exploiting unmanned surveillance system properly over multi-channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.9-17
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• 2004

Adapt ive and fixed step size PC (power control) schemes for accommodating voice, video, and data are evaluated according to the different PC command rates and their effects on integrated Voice/Video/Data are investigated. The required minimum power levels are derived as PC thresholds and the effects of PC errors on channel quality and radio 1 ink capacity are investigated. The services with high bit rates and low bit error rates can cause a significant effect on the radio link qualifies of the other types of traffic. The results show that the adapt ive step size PC scheme for voice/video/data services can achieve more capacity and cause less interference to the radio channels because less minimum PIL(Power Increment Level) is required for the specified radio link outage probability.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.23-33
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• 2009

A shot change detection technique is an important technique for effective management of video data, thus it requires an adaptive algorithm for various video sequences to detect an accurate shot change frames. In this paper, we propose an adaptive shot change detection algorithm using histogram mean of frames within extension sliding window. Our algorithm calculates a frame feature value using histogram and defines an adaptive threshold using an average of histogram mean of frames within the extension sliding window and determines a shot change by comparing the feature value and the threshold. We obtained better detection rate than the conventional methods maximally by 15% in the experiment with the same test sequence. We verified real-time operation of shot change detection in the hardware platform with low performance by implementing it on TVUS HM-900 PLUS model of Homecast. The Proposed algorithm can be useful in the hardware platform such as portable multimedia player(PMP) or cellular phone with low CPU performance.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.1
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• pp.29-34
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• 2012

Wireless multicast service can be used for video streaming service to save the network resources by sending the same popular multimedia contents to a group of users at once. For better multimedia streaming multicast service, we propose a quality-aware rate adaptation (QARA) scheme for scalable video multicast in rate adaptive wireless networks. In QARA, transmission rate is determined depending on the content's type and users' channel conditions. First, the base layer is transmitted by a low rate for high reliability. That means we provide basic service quality to all users. On the contrary, the transmission rate for enhancement layer is adapted by using channel condition feedback from a randomly selected node. So, the enhancement layer frames in a multimedia content is sent with various transmission rates. Therefore, each node can be provided with differentiated quality services. Consequently, QARA is capable of serving heterogeneous population of mobile nodes. Moreover, it can utilize network resources more efficiently. Our simulation results show that QARA outperforms utilization of the available transmission rate and reduces the data transmission time.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.111-113
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• 2010

본 논문에서는 SVC(Scalable Video Coding) 및 MVC(Multiview Video Coding) 등의 다계층 비디오의 효율적인 적응 HTTP 스트리밍을 위한 MPEG-2 TS(Transport Stream) 헤더의 확장을 제안한다. 먼저 TS로 다중화한 SVC/MVC를 HTTP를 통하여 스트리밍 할 경우 계층별 적응 스트리밍을 지원하기 위한 기존 TS의 한계점을 분석하고, TS 헤더의 확장을 통하여 TS 레벨에서 효율적인 적응을 제공하는 시그널링 기법을 제시한다. 본 논문의 제안 기법은 TS 헤더의 private_data를 추가적으로 정의하여 스케일러빌리티 및 뷰 정보를 기술함으로써 TS 단위로 스케일러블 계층 및 뷰 간 적응 스트리밍을 제공한다.

• Journal of KIISE
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• v.44 no.5
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• pp.545-552
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• 2017

Because of the explosive growth of mobile devices and development of network technologies, HTTP (Hypertext Transfer Protocol) adaptive streaming has become a new trend in video delivery to provide efficient multimedia streaming services. As interest in personalized broadcasting grows, the study of interactive multimedia has been actively pursued. The interactive multimedia service is a method of playing media according to a scenario selected by the user. Providing the interactive multimedia service with the existing HTTP adaptive streaming causes switching delay and buffer underflow according to the point in time when the user selects the scenario while the client streams the interactive multimedia and therefore decreases the user QoE (Quality of Experience). In this paper, we propose an adaptive streaming scheme for interactive multimedia service in HTTP adaptive streaming to provide seamless playback. We design the architecture and prefetching scheme for interactive multimedia streaming.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.421-430
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• 2006

In this paper, we propose a practical implementation of network-adaptive HD(high definition) MPEG-2 video streaming with a cross-layered channel monitoring(CLM) over the IEEE 802.11a WLAN(wireless local area network). For wireless channel monitoring, AP(access point) periodically measures the MAC(medium access control) layer transmission information and sends the monitoring information to a streaming server. This makes that the streaming server reacts more quickly as well as efficiently to the fluctuated wireless channel than that of the end-to-end monitoring(E2EM) scheme for the video adaptation. The streaming sewer dynamically performs the priority-based frame dropping to adjust the video sending rate according to the measured wireless channel condition. For this purpose, our streaming system nicely provides frame-based prioritized packetization by using a real-time stream parsing module. Various evaluation results over an IEEE 802.11a WLAM testbed are provided to verify the intended QoS adaptation capability The experimental results show that the proposed system can effectively mitigate the quality degradation of video streaming caused by the fluctuations of time-varying wireless channel condition.

• Journal of Chest Surgery
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• v.33 no.11
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• pp.898-903
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• 2000

배경 및 목적: 최근 비디오 흉강경술은 최소 침습적인 수술 방법으로서 자연 기흉의 일반적 치료법으로 인정되고 있으나 비교적 높은 재발율과 비용-효용 관계에 대해서는 논란이 있다. 비디오 흉강경을 이용한 기포 절제술 후의 재발율은 평균 5-10%정도로 보고되고 있으며 이는 개흉술에 비해 상당히 높은 것이다. 또한 국내 의료 실정에서의 개흉술과 비디오 흉강경술의 비용효용에 대한 비교 통계는 없는 상황이다. 대상 및 방법: 1997년 1월부터 1999년 7월까지 일차성 자연기흉으로 성균관 의대 강북삼성병원 흉부외과에서 수술을 시행한 173예를 대상으로 후향적 조사하였다. 비디오 흉강경술로 시행한 104예와 개흉술로 시행한 69예를 양군으로 나누어 성별 및 연령, 발병부위, 수술의 적응증, 수술시간, 술 후 흉관 삽입기간 및 재원 일수, 술후 합병증, 재발율, 수술 경비 및 총치료경비 등을 비교하였다. 결과: 양군의 성별, 연령, 발병부위 등에는 차이가 없었다. 수술 시간은 흉강경군이 73.1$\pm$29.5분, 개흉군이 141$\pm$52분이었다.(p<0.05). 술 후 평균 흉관의 거치기간 및 재원일수는 흉강경군이 각각 3.93일 및 7.5일, 개흉군이 7.0일 및 13.4일이었다.(P<0.05, P<0.05). 술 후 재발한 경우가 비디오 흉강경군에서 6예(5.6%), 개흉군에서 1예(1.4%) 있었다(P<0.05). 본원에서 시행한 비디오 흉강경술과 개흉술의 비교에서 수술로 발생하는 비용은 비디오 흉강경군이 유의하게 높았으나 (1,202,192$\pm$178,992원, 1,005,669$\pm$311,531원; P<0.05) 총 치료비의 비교에서는 유의한 차이가 없었다.(1,946,110$\pm$487,440원, 1,793,912$\pm$308,079원; P=0.18). 결론: 비용 효용관계 및 재발율은 병원마다의 수술 수기 및 퇴원 정책등에 따라서 다소간의 차이가 있을 수 있으나 본원의 조사 결과에서는 비디오 흉강경술이 개흉술에 비해 비용-효과가 있다고 볼 수 없으며 재발율도 높았다.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.743-754
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• 2019

System for three degrees of freedom plus (3DoF+) and 6DoF requires multi-view high resolution 360 video transmission to provide user viewport adaptive 360 video streaming. In this paper, we implement 3DoF+ 360 video compression system which removes the redundancy between multi-view videos and merges the residual into one video to provide high quality 360 video corresponding to an user's head movement efficiently. Implementations about 3D warping based redundancy removal method between 3DoF+ 360 videos and residual extraction and merger are explained in this paper. With the proposed system, 20.14% of BD-rate reduction in maximum is shown compared to traditional high-efficiency video coding (HEVC) based system.

• 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.