• KIISE Transactions on Computing Practices
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• v.21 no.12
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• pp.780-785
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• 2015

Recently HTTP (Hypertext Transfer Protocol) adaptive streaming services have been the subject of much attention. The video quality control scheme of conventional HTTP adaptive streaming services estimates bandwidth using segment throughput and smooths out the sample of segment throughput. However, the conventional scheme has the problem of QoE (Quality of experience) degradation occurring with buffer underflow and frequent quality change due to the fixed number of samples. In order to solve this problem, we propose a video quality control scheme based on segment throughput and buffer occupancy. The proposed scheme determines the number of samples according to the variation of segment throughput. The proposed scheme also controls video quality based on the threshold of bitrate to keep stable buffer occupancy. The simulation results show that proposed scheme improves QoE by preventing buffer underflow and decreasing quality change when compared with the conventional scheme.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.1
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• pp.287-310
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• 2011

This research surveyed college students in Korea on their satisfaction for e-book services provided by university libraries. Their usage behavior was investigated, and the satisfaction rate for e-book usage and its service quality were analyzed to comprehend the status of e-book usage. The analysis showed that overall satisfaction for e-book service of university libraries was 2.93 on average. Moreover, the more frequently a student used the service, the more satisfied the student was; junior/senior-level and graduate school student groups showed higher satisfaction for e-book service than freshman and sophomore students. The most influential factor for satisfaction based on the e-book service quality was the content of the service, followed by the library support service system. Based on the findings, reinforcement of library public relations and user education, and the maintenance of the variety and up-to-date status of the contents were proposed to stimulate future university library e-book services.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.333-336
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• 2009

본 논문에서 우리는 차세대 통합망 환경에서 제공된 IPTV 서비스를 이용하는 서비스 가입자의 품질 만족도가 저하될 경우 이와 관련된 네트워크 계층의 QoS 품질 파라미터를 제어함으로써 서비스 품질 만족도를 향상시킬 수 있는 시스템을 제안한다. IPTV 서비스 이용자의 체감 품질(QoE)을 향상시키기 위해, 우리는 IPTV의 멀티미디어 서비스 품질 및 전송 계층의 품질 파라미터간 연동 제어 시스템의 세부 기능 및 동작 절차를 개발하였다. 제안된 시스템을 통해 IPTV 멀티미디어 서비스 및 네트워크 사업자들은 멀티미디어 서비스의 특성 및 네트워크 상황을 고려하여 서비스 이용자에게 향상된 품질의 멀티미디어 서비스를 제공할 수 있다.

• Journal of KIISE
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• v.44 no.4
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• pp.423-432
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• 2017

Recently, the video quality control schemes for the improvement of the QoE (Quality of Experience) of video streaming services that are based on DASH (Dynamic Adaptive Streaming over HTTP), which is a standard of HTTP adaptive streaming (HAS) services, have been studied. However, the problem of the existing schemes is the degradation that is due to unnecessary quality changes because the VBR (Variable Bitrate) characteristics of the video are not considered. In this paper, we propose a SC-DASH (Segment Characteristics-based DASH) which controls the video quality based on the segment characteristics. The SC-DASH can prevent the occurrence of the unnecessary quality changes by controlling the video quality based on the size of the next segment, the segment throughput, and the buffer occupancy. The experiment results showed that the SC-DASH improves the QoE by reducing the unnecessary quality changes compared with the existing quality control schemes.

• Journal of KIISE
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• v.44 no.1
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• pp.95-106
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• 2017

HTTP adaptive streaming has recently emerged to handle the rapidly growing traffic and to provide high quality multimedia contents. To improve the QoE (Quality of Experience) for HTTP adaptive streaming service, the average video bitrate should be maximized, and the video switching frequency (difference of bitrate between adjacent segments) and video stalling events need to be minimized. The recently proposed quality adaptation algorithms for HTTP adaptive streaming do not provide high QoE, since detailed QoE factors such as video switching frequency and bitrate difference of adjacent segments, are not considered. In this paper, we propose a SQA (Smooth Quality Adaptation) algorithm to improve the user QoE. The proposed algorithm provides the smoothed QoE, such that it minimizes the unnecessary video switching events by maintaining the quality in a certain period, thus minimizing the bitrate difference of adjacent segments. Through simulation, we confirm that the proposed algorithm reduces the unnecessary switching events, and prevents the sudden decrease in video quality.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.82-87
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• 2015

There are many current researches that are looking to improve the quality of HTTP adaptive streaming services. However, the existing schemes have a serious problem of QoE (Quality of Experience) degradation because few consider VBR video transmission. To cope with this problem, in this paper, we proposed a novel media quality adaptation scheme called CB-DASH (Content and Buffer-aware DASH). The proposed scheme controlled the video quality considering the VBR characteristics of video and the client's buffer state. Through the simulation, we proved that our scheme accomplished a more accurate estimated bandwidth than the conventional DASH and improved the QoE of streaming service.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2728-2732
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• 2009

Recently, the instances of communications between the applications and interaction applications using the Web services in the implementation of the business logics among the enterprises are spread widely. Therefore the efficient business operational models are more and more required. The usage of the services which guarantee the optimum level of service quality among the various Web services is also required. In this paper the Web services are analyzed. The required security and the service quality for the enterprises are analyzed. And then an e-Business operational model which is applicable to the enterprise business environment is proposed.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.171-177
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• 2020

This study investigates e-service quality of online travel agency and influence on relationship quality and Reuse. The individual Chinese tourists with experiences using online travel agencies were chosen for the study. The survey was carried out at Jeju International Airport, which is the most frequently used by Chinese tourists visiting Korea. Data were collected for 7 days from July 15, 2019 to July 21, 2019. A total of 320 tourists were attended in this research and finally 300 samples were used for empirical analysis. The result of the study showed that e-service quality of online travel agencies all factors(convenience, individuality, accuracy and price attractiveness) influences on relationship quality all factors(satisfaction, trust) and the factor 'accuracy' was analyzed as the biggest among them. Moreover satisfaction and trust factors of all sub-factors of relationship quality influences on reuse. In the future, we intend to provide basic marketing data for Chinese tourists using online travel agencies to officials and practitioners. Particularly, focusing on the tourism behaviors of individual Chinese tourists, we are going to propose effective business cooperation plans and strategic alternatives with online travel agencies.

• 한국IT서비스학회:학술대회논문집
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• 2010.05a
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• pp.177-182
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• 2010

최근 통신서비스는 유무선환경이 융 복합되어지고, 통신의 주체도 기존의 전화, 휴대전화, PC에서 센서를 이용한 사물통신까지 다양해지고 있다. 이러한 통신환경의 변화는 수년간 논의되어온 유비쿼터스서비스(Ubiquitous Service, U-Service)로 발전되어지는 것이라 할 수 있다. 기존의 통신 서비스의 경우에는 회선의 대역폭이나 손실률, 지연율 등이 통신서비스의 품질을 크게 좌우했지만, 통신환경이 복잡해지면서 통신서비스의 품질을 좌우하는 요소 또한 다양해지고 있다. 특히 U-Service에서는 기존과는 다른 통신환경을 가지고 있는 센서와 센서를 위한 센터 네트워크가 한 부분으로 포함되면서 통신서비스의 품질을 관리하는 것은 상당히 어려워지고 있다. 본 논문에서는 U-Service에서의 품질에 관한 기존의 연구와 통신서비스에서의 품질에 관한 연구를 분석하고, U-Service에서의 품질에 대한 정의 및 품질 관리방안에 대해서 제안한다.

• Journal of Advanced Navigation Technology
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• v.15 no.1
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• pp.76-82
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• 2011

Most previous work on network selection in heterogeneous wireless networks has concentrated on the quality of the network alone. Therefore, users are not satisfied with network quality based network selection due to different user preferences. To solve this problem, we proposes a QoE-aware network selection algorithm that is based on the consumption patterns of user preferences which is divided into normal user, cost-sensitive user, quality-sensitive user and video quality as well as network quality. As a result of experiments, cost-sensitive user and quality-sensitive user are satisfied with enhanced QoE by 36% and 3% from the proposed network selection algorithm compared to the normal user, respectively.