• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.660-675
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• 2018

This study is designed to investigate how the perceived characteristics of the online video services affect the 'flow' as positive experience and satisfaction of users. For the study, we conducted a questionnaire survey on 289 people using YouTube, and then analyzed the relationships among variables using hierarchical regression analysis. As a result, it was confirmed that interactivity, newness of recommendation service, diversity of content, and entertainingness of contents all affect the lower level of flow experience. On the other hand, the accuracy of the recommendation service did not affect the flow experience, but positively affects the level of satisfaction. Finally, it is also confirmed that flow has a direct effect on user satisfaction, and mediates relationship between the characteristics of YouTube and satisfaction. The results of this study are helpful to understand user's perception and experience of online video platform service and suggest the discussion points to be considered by the industry to satisfy users.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.339-344
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• 2021

The purpose of this study is to present measures to enhance non-face-to-face communication platform services by measuring the user experience elements of major videoconferencing platforms in the non-face-to-face era. As a method of research, the platform of Zoom and MS Teams was selected, and the factors affecting the user experience were evaluated in combination with task and Think Aloud, and seven Honeycomb models of Peter Mobil were reconstructed to be analyzed through surveys and in-depth interviews for each paragraph. Studies have shown that Zoom has high usability, usability, accessibility and searchability, and MS Teams have excellent attractiveness. Therefore, based on the results of this study, the guidelines for video conferencing platform services and the improvement of the interface were presented. Based on this study, we hope that the usability of videoconferencing will be improved, and that various related studies will proceed as follow-up studies.

• Journal of Information Technology Services
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• v.14 no.1
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• pp.99-113
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• 2015

Adaptive bitrate (ABR) streaming technology has become an important and prevalent feature in many multimedia delivery systems, with content providers such as Netflix and Amazon using ABR streaming to increase bandwidth efficiency and provide the maximum user experience when channel conditions are not ideal. Where such systems could see improvement is in the delivery of live video with a closed loop cognitive control of video encoding. In this paper, we present streaming camera system which provides spatially and temporally adaptive video streams, learning the user's preferences in order to make intelligent scaling decisions. The system employs a hardware based H.264/AVC encoder for video compression. The encoding parameters can be configured by the user or by the cognitive system on behalf of the user when the bandwidth changes. A cognitive video client developed in this study learns the user's preferences (i.e. video size over frame rate) over time and intelligently adapts encoding parameters when the channel conditions change. It has been demonstrated that the cognitive decision system developed has the ability to control video bandwidth by altering the spatial and temporal resolution, as well as the ability to make scaling decisions

• Journal of Korea Multimedia Society
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• v.21 no.10
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• pp.1182-1194
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• 2018

The Dynamic Adaptive Streaming over HTTP(DASH) is envisioned to evolve to meet an increasing demand on providing seamless video streaming services in the near future. The DASH performance heavily depends on the client's adaptive quality selection algorithm that is not included in the standard. The existing conventional algorithms are basically based on a procedural algorithm that is not easy to capture and reflect all variations of dynamic network and traffic conditions in a variety of network environments. To solve this problem, this paper proposes a novel quality selection mechanism based on the Deep Q-Network(DQN) model, the DQN-based DASH Adaptive Bitrate(ABR) mechanism. The proposed mechanism adopts a new reward calculation method based on five major performance metrics to reflect the current conditions of networks and devices in real time. In addition, the size of the consecutive video segment to be downloaded is also considered as a major learning metric to reflect a variety of video encodings. Experimental results show that the proposed mechanism quickly selects a suitable video quality even in high error rate environments, significantly reducing frequency of quality changes compared to the existing algorithm and simultaneously improving average video quality during video playback.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.405-411
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• 2019

The purpose of the study is to investigate a usability of using fashion and beauty service and suggest better user experience on Instagram's newly released mobile video platform, IGTV. The study expects to be a resource of improving the usability on fashion and beauty contents on IGTV and encourage further research for suggesting better guidelines. As a research method, it will experiment current mobile video service first with literature review. Afterwards, the research conducted tasks and in-depth interview with eight Instagram users to evaluate a usability of using fashion and beauty service on IGTV. As a result, it is able to derive two plans that needed improvement. Firstly, IGTV is required to have high accessibility for user's to use service longer and intuitive user experience. Secondly, unlike previous service that Instagram have offered, IGTV need to differentiate to share and get information of fashion and beauty trends.

• Journal of Broadcast Engineering
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• v.19 no.5
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• pp.713-725
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• 2014

Multi-view and 3D video technologies for a next generation video service are widely studied. These technologies can make users feel realistic experience as supporting various views. Because acquisition and transmission of a large number of views require a high cost, main challenges for multi-view and 3D video include view synthesis, video coding, and depth coding. Recently, JCT-3V (joint collaborative team on 3D video coding extension development) has being developed a new standard for multi-view and 3D video. In this paper, major tools adopted in this standard are introduced and evaluated in terms of coding efficiency and complexity. This performance analysis would be helpful for the development of a fast 3D video encoder as well as a new 3D video coding algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.314-321
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• 2011

There have been considerable standardization works to measure subjective video quality. However, these standardization methods are based on the situation where they have original or reference video sequences, and measure the video quality by looking the sequence during short time duration, e.g. 10 seconds. Since people's TV watching time durations in IPTV services are very long (e.g. more than 30 minutes), the quality measurements by the standards are not practical. In this paper, we analyze the effect of video quality rating period to MOS (Mean Opinion Score), and suggest a proper rating duration of subjective video quality for IPTV services.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.2
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• pp.331-338
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• 2019

Video services over Internet is getting important. Since the service quality of the video service provided by streaming over Internet may be degraded, the quality assessment and management are very important. Currently the objective method based on the measured values of parameters is being widely used for video services. The subjective assessment, however, is more ideal in that the quality that is experienced by human. This paper, therefore, proposes a subjective quality management scheme for video service in a mobile environment that overcomes the limitations of the subjective method. The proposed scheme is expected to contribute to implement a more efficient quality management system for video services in a mobile environment.

• ETRI Journal
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• v.43 no.3
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• pp.447-458
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• 2021

The quality of experience (QoE) of video streaming is degraded by playback interruptions, which can be mitigated by the playout buffers of end users. To analyze the impact of playout buffer dynamics on the QoE of wireless adaptive hypertext transfer protocol (HTTP) progressive video, we model the playout buffer as a G/D/1 queue with an arbitrary packet arrival rate and deterministic service time. Because all video packets within a block must be available in the playout buffer before that block is decoded, playback interruption can occur even when the playout buffer is non-empty. We analyze the queue length evolution of the playout buffer using diffusion approximation. Closed-form expressions for user-perceived video quality are derived in terms of the buffering delay, playback duration, and interruption probability for an infinite buffer size, the packet loss probability and re-buffering probability for a finite buffer size. Simulation results verify our theoretical analysis and reveal that the impact of playout buffer dynamics on QoE is content dependent, which can contribute to the design of QoE-driven wireless adaptive HTTP progressive video management.

• Quality Improvement in Health Care
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• v.19 no.1
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• pp.56-61
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• 2013

Objectives: This video has been produced to provide better awareness for our patients about radiotherapy treatment for anxiety and stress. This video will give inexperienced patients a better understanding of the processes and expectations of the radiotherapy. We have produced a radiotherapy guidance video regarding work flow and a method of radiotherapy to relieve anxiety and stress. It also improves patients satisfaction and understanding of radiotherapy to provide a high-quality health care for radiotherapy patients with indirect experience. Methods: We have evaluated the effectiveness of the video compared to our existing verbal method. See below for the evaluation criteria; 1) Patients satisfaction rate of guidance 2) a comparison of understanding of radiotherapy 3) a comparison of a time of education for patients 4) a researching of an incidence rate of radiotherapy. Results: When compared to the verbal explanation the patients had a increased level of understanding of the radiotherapy treatment. The time to educate patient was decreased and the level of incidents during the treatment was decreased due to the patient having a better understanding of the whole process. Conclusion : In conclusion, the audiovisual education increased the understanding of radiotherapy for patients compared to verbal education. The video also helped patients to cooperate in treatment room so we can provide premium radiotherapy treatment. By reducing the treatment time and education processa we improved the patients overall experience.