• 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.

• Journal of KIISE
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• v.42 no.8
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• pp.1039-1048
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• 2015

Recently, the web-based adaptive streaming service, DASH (Dynamic Adaptive Streaming over HTTP), is receiving more attention. However, existing network-based and buffer-based video quality control schemes in DASH environments make oscillation of segment throughput, causing degradation of the quality of experience (QoE) with frequent quality changes and playback interruptions because these schemes do not consider the content characteristics. In this paper, we propose a C-DASH (Content Characteristics based Dynamic Adaptive Streaming over HTTP) scheme in order to improve the QoE in DASH environments. The C-DASH scheme performs seamless and smooth quality control based on the segment throughput, buffer status, and segment size of the content. Based on simulation results, it is confirmed that the C-DASH scheme can improve the QoE, when compared with the existing quality control schemes.

• Journal of KIISE
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• v.44 no.6
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• pp.628-636
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• 2017

HTTP adaptive streaming is a technique that improves the quality of experience by storing various quality videos on the server and requesting files of the appropriate quality based on network bandwidth. However, it is difficult to measure the actual bandwidth in wireless networks with frequent bandwidth changes and high loss rate. Frequent quality changes and playback interruptions due to bandwidth measurement errors degrade the quality of experience. We propose a technique to estimate the available bandwidth by measuring the jitter, which is the derivation of delay, on a packet basis and assigning a weight according to jitter. The proposed scheme reduces the number of quality changes and mitigates the buffer underflow by reflecting less bandwidth change when high jitter occurs due to rapid bandwidth change. The experimental results show that the proposed scheme improves the quality of experience by mitigating buffer underflow and reducing the number of quality changes in wireless networks.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.719-726
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• 2014

This paper addresses quality of experience(QoE) and how to measure and evaluate QoE including its subjective aspects. Adopting the real measurements on the field, a various quality metric have been measured for VoIP(voice over IP) service provided through a wireless interface of WiBro(Wireless Broadband). By analyzing the measured values and correlation between the metrics, we attempt to find a method to evaluate QoE of the VoIP service in a objective way. As a result, it has been shown that QoE of the VoIP service through WiBro network has close relation to the packet-level end-to-end delay, and the delay has close relation to received signal strength indicator(RSSI).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1031-1037
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• 2001

본 고에서는 요즘 전세계적으로 관심을 모으고 있는 정보통신 산업과 기술발전으로 인한 이동전화의 서비스 품질평가에 대한 방법을 정리하였다. 주요 내용으로는 이동전화 체감 통화품질 측정을 위한 시험조건 및 시험방법개선, 시험장비 기능 확인시험, 성능개선 요구 및 확인, 시험계획 수립 및 전국 측정 방법, 측정데이터 분석, 등급별 평가 등에 대한 내용으로, 특히 이동전화 품질평가 항목별 시험조건 및 시험방법, 이동전화 체감 품질 측정용 시험장비 성능/신뢰성 개선 그리고 전국 현장 측정 데이터분석 및 지역별 품질 산출, 등급별 평가 내용을 정리하였다. 또한 각 분야별 품질 평가 기술 방법에 패한 우리나라의 대응전략을 정리하여 산업체 기술개발에 많이 활용될 수 있을 것으로 사료된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.419-425
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• 2001

본 고에서는 요즘 전세계적으로 관심을 모으고 있는 정보통신 산업과 기술발전으로 인한 이동전화의 서비스 품질평가에 대한 방법을 정리하였다. 주요 내용으로는 이동전화 체감 통화품질 측정을 위한 시험 조건 및 시험방법개선, 시험장비 기능 확인시험, 성능개선 요구 및 확인, 시험계획 수립 및 전국 측정 방법, 측정데이터 분석, 등급별 평가 등에 대한 내용으로, 특히 이동전화 품질평가 항목별 시험조건 및 시험 방법, 이동전화 체감 품질 측정용 시험장비 성능/신뢰성 개선 그리고 전국 현장 측정 데이터분석 및 지역별 품질산출, 등급별 평가 내용을 정리하였다. 또한 각 분야별 품질 평가 기술 방법에 대한 우리나라의 대응전략을 정리하여 산업체 기술개발에 많이 활용될 수 있을 것으로 사료된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1267-1270
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• 2006

최근들어 초고속 통신망(xDSL, FTTH, Cable)을 이용하여 Head-End Server에서 가입자 댁내의 셋탑박스를 TV를 이용하여 멀티미디어(다채널 SD/HD 방송, VOD) 및 양방향 인터넷 연동 서비스(T-Portal, T-Communication) 등을 제공하는 것이 가능해 졌다. 더불어 고객들에게 인터넷을 통한 이 서비스의 품질을 보장하는 망 관리 관점에서의 기능도 필요하게 되었다. 고객들은 예전보다 더 나은 통신품질을 제공받기를 기대하고 있다. 따라서, 기존의 PE-to-PE 통신 품질 뿐만 아니라 CE-to-CE 통신 품질도 제공함으로써 고객체감품질 보증의 만족도를 향상시켜야 한다 본 논문에서는 IP 서비스(IPTV, VoIP 등)의 SLA에서 사용될 품질 지표에 관한 연구 및 PE-to-PE구간에서 부터CE-to-CE 구간 까지의 시스템 망 구성도, SLA 관리시스템에 관해 설명한다. 본 논문의 SLA 시스템에서는 가입자 댁내의 셋탑박스에 내장된 품질측정 Agent를 이용하여 통신품질 데이터를 측정한 후, 가공하여 SLA를 적용함으로써, 보다 정확한 고객체감품질 보증 및 고객에게 SLA의 신뢰성을 줄 수 있다. 또한, 서비스 제공자로 하여금 사전에 통신품질을 감시할 수 있는 기능을 제공함으로써 양질의 통신품질을 보장할 수 있도록 하는데 목적이 있다.

• 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.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06a
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• pp.214-215
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• 2010

• 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.