• Journal of Korean Society for Geospatial Information Science
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• v.21 no.1
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• pp.53-64
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• 2013

Since 2000, ubiquitous cities are spread over Korea by government's supporting project for ubiquitous city construction. But recently problems such as low perception of ubiquitous city are issued. There is just a few studies about a creation of citizen centric ubiquitous city service even though there have been several studies and policies to overcome such problems. There is not enough research on applying ubiquitous city service effectively at the stage of ubiquitous city plan. To solve this problems, this study ultimately aims to suggest essential ubiquitous city service applied at that stage to guarantee minimum quality of ubiquitous city. The expert survey method was employed to select essential ubiquitous city service. To achieve this goal, First, a survey performed by 163 local government officers to know current status of the ubiquitous city construction project. Second, another survey was performed for about 30 days by 38 experts worked at local public official and ubiquitous city organization to select essential ubiquitous city service. Finally we suggested 14 essential ubiquitous city service from the several viewpoints, which were universality, industry growth, social welfare, effective city management. And we analyzed the differences between ubiquitous city services written 14 ubiquitous city plan and essential ubiquitous city services.

• Journal of the HCI Society of Korea
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• v.6 no.1
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• pp.27-33
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• 2011

The battery lifetime is one of the most important factors in product qualities of mobile devices such as mobile phones, MP3 players, PMP. It is used to be displayed by a 'battery bar' icon with uniformly divided three or four blocks. However, several manufacturers of mobile phones have assigned uneven time ratios to each battery block because they believe that it can make users feel more long in battery lifetime. In this study, two experiments were performed. The first is to verify the effects of the uneven time ratios in each battery block on users' cognitive awareness of battery lifetime. The second is to investigate whether the compatibility between battery displays and actual time ratios affects the users' time perceptions. The results show that as low battery bar is maintained for a long time, users tend to be aware of the battery lifetime shorter. On the contrary, maintaining full battery status longer does not affect the users' time perception. These results can be applied as the guidelines for determining proper time ratios in designing the battery bar indicator of mobile devices.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.4
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• pp.379-384
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• 2010

The service quality is one of the most important issue for successful deployment of IPTV services. Currently, a number of parameters have been reported that they have an effect on the quality of IPTV services. However, it is almost impossible to monitor and manage all the parameters in real time. Key parameters, therefore, should be chosen as a service metric for efficient quality management of IPTV services. For this purpose, we implement an environment for monitoring and measuring the quality of IPTV services and try to figure out the effect of each parameter on the quality of IPTV services. In particular, we focus on a parameter called continuous count error (CCE) measured at the level of MPEG transport stream (TS) and show that it has a greater effect on the quality of IPTV services than other parameters.

• Journal of KIISE:Information Networking
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• v.37 no.6
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• pp.483-488
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• 2010

Due to the prevalence of various mobile devices and wireless broadband networks, there has been a significant increase in interest and demand for multimedia streaming services. Moreover, the user can service the participatory video broadcasting service in the mobile device and it can be used to deliver the real-time news and more variety information in the user side. Live multimedia service of user participation should consider not only the video quality but also the delay bounds and continuity of video playback for improving the user perceived QoS (Quality of Service) of streaming service. In this paper, we propose an adaptive rate control scheme, called DeBuG (Delay Bounds Guaranteed), to guarantee the delay bounds and continuity of video playback for the real-time streaming in mobile devices. In order to provide those, the proposed scheme has a quality adaptation function based on the transmission buffer status and network status awareness. It also has a selective frame dropper, which is based on the media priority, before the transmission video frames. The simulation results demonstrate the effectiveness of our proposed scheme.

• Journal of Information Management
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• v.37 no.4
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• pp.69-91
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• 2006

The purpose of this study is to improve the effectiveness and quality of web service by analyzing the web service problems and suggesting the solutions through the expert service quality evaluation from the point of view of users and website quality evaluation by measurement tools for a whole NDSL website. In case of website analysis, this study analyzed the website completeness of NDSL site and looked into the problem that users can judge by intuition during their use of the site, and evaluated the searchability and usability for web-based service quality evaluation by centering on the service quality of database quality items. After the results of this analysis, it appeared that there was not a big problem on the use. But after searching, several problems were found on loading rates, website completeness, user sensitiveness, the protection of private information, metadata completeness, website accessability, etc. And as a result of the evaluation of website service quality, it does not show the all satisfactory results in the function of search methods and search result printing, mark list and the items related to full-text in the part of searchability and usability. However, comparing with the results of other information organizations, it shows the similar level of quality.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.121-123
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• 2006

초고속 네트워크가 점점 일반화됨에 따라 네트워크를 기반으로 하는 멀티미디어 서비스에 대한 요구도 점점 확대되고 있으며, 동시에 보다 실감 멀티미디어 데이터에 대한 기대 역시 커지고 있다. 입체음향 기술은 음향 부분의 실감성을 향상시키는 방법으로, 네트워크 참여자들의 가상현실 환경 공유 상황에서 체감 품질을 보다 더 향상시키는 역할을 할 수 있다. 본 논문에서는 입체음향 기능들을 네트워크를 통해 전달하고 활용하는데 필요한 요소에 대해 논의하고 그 처리 방법을 제시한다. 아울러 제시한 방법을 적용할 수 있는 활용 분야에 대해서 다룬다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.7
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• pp.28-35
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• 1998

본 논문에서는 아날로그 이동 전화 환경에서의, 객관적인 음질 평가 척도를 사용하 여 주관적 음질을 추정하는 이동전화 자동 음질평가 시스템을 개발하였다. 이동전화의 통화 품질을 유지하기 위해서는 이동전화의 네트워크를 계속하여 체크하는 것이 매우 중요하다. 주관적 음질 평가는 사람의 체감을 직접 나타내는 것이므로 실제적인 음질을 평가하는데 중 요한 척도가 되지만, 인력과 시간이 많이 소모되므로 다양한 지역에서 지속적으로 음질을 평가하는데 부적절하다. 이러한 문제를 해결하기 위하여 객관적 음질평가 척도를 이용하여 주관적 음질 평가 척도를 예측하는 자동 음질 평가 시스템이 필수적이다. 반복된 실험을 통 하여 BSD(Bark Spectral Distance)가 주관적 음질 평가 척도와 높은 상관관계가 있음을 확 인하였으며 원래의 음성과 이동 전화 채널을 통과한 음성과의 BSD를 측정한 후 이를 바탕 으로 MOS(Mean Opinion Score)를 추정하는 자동 음질 평가 시스템(Automatic Speech Quality Evaluator)을 개발하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.535-539
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• 2007

본 논문에서는 다양한 서비스가 복합적으로 운용되고 있는 콜 센터도입과 콜 센터 도입으로 인한 자치단체에 미치는 파급효과에 대하여 긍정적인 측면과 부정적인 측면을 예상해 보고, 콜 센터 도입의 우선순위 즉 광역자치단체부터 콜 센터를 먼저 도입하는 것이 어떻게 효과적인지 살펴보고 콜 센터 도입에 대한 합리적이 접근 방법을 모색함으로써 고품질의 국민 체감형 행정서비스를 언제(anytime), 어디서나(anywhere), 누구나(anybody)쉽고 편리하게 이용하고 정부에 대한 국민 참여기회 확대 및 국민과 정부가 상호작용 할 수 있는 콜 센터 환경 구축에 대한 전략을 전국공통 120번 생활 민원 전화번호를 활용하여 연구하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.867-871
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• 2013

In this paper, a major factor in determining voice quality that corresponds to the jitter and jitter buffer algorithm for removing jitter will be described. We analyze various jitter buffer algorithms and suggest ways to improve performance of jitter buffer algorithm.

• Journal of KIISE
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• v.45 no.2
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• pp.175-186
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• 2018

Recently, HAS (HTTP Adaptive Streaming) has been the subject of much attention to improve the QoE (Quality of Experience). In a high latency network, HAS degrades the QoE due to the lost RTT cycle since it replies with a response of one segment to the request of one segment. The server-push based HAS schemes of downloading multiple segments in one request cause QoE degradation due to the buffer underflow. In this paper, we propose a VSSDS (Video Streaming Scheme based on Dynamic Server-push) scheme to improve the QoE in a high latency network. The proposed scheme adjust video quality by estimating available bandwidth and determine the number of segments to be downloaded for each segment request cycle. Through the simulation, the proposed scheme not only improves the average video bitrate but also alleviates the buffer underflow.