• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.308-324
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• 2018

HTTP adaptive streaming (HAS) is a promising technology for delivering video content over the Internet. HAS-based video streaming solutions rely on bandwidth estimation to select the appropriate video bitrate. Video streaming solutions that consider network conditions provide users with seamless video playback. However, when multiple clients compete for a common bottleneck link, conventional bandwidth estimation schemes that consider only one client overestimate the network bandwidth due to the ON-OFF traffic pattern. The bandwidth overestimation can cause Quality of Experience (QoE) degradation, such as unnecessary changes in video quality, and unfairness of video quality. In this paper, we propose a client-side bandwidth estimation scheme to obtain a better QoE of HAS in the multiple-client environment. The proposed scheme differentiates the client buffer status according to the buffer occupancy, and then estimates the available network bandwidth based on the buffer status and segment throughput. We evaluate the performance of HAS implemented in the ns-3 network simulator. Simulation results show that compared with the conventional schemes, the proposed scheme can enhance the QoE.

• Journal of Preventive Medicine and Public Health
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• 제54권3호
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• pp.161-165
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• 2021

Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads heterogeneously, disproportionately impacting poor and minority communities. The relationship between poverty and race is complex, with a diverse set of structural and systemic factors driving higher rates of poverty among minority populations. The factors that specifically contribute to the disproportionate rates of SARS-CoV-2 infection, however, are not clearly understood. Methods: We evaluated SARS-CoV-2 test results from community-based testing sites in Los Angeles, California, between June and December, 2020. We used tester zip code data to link those results with United States Census report data on average annual household income, rates of healthcare coverage, and employment status by zip code. Results: We analyzed 2 141 127 SARS-CoV-2 test results, of which 245 154 (11.4%) were positive. Multivariable modeling showed a higher likelihood of SARS-CoV-2 test positivity among Hispanic communities than among other races. We found an increased risk for SARS-CoV-2 positivity among individuals from zip codes with an average annual household income

• 한국비블리아학회지
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• 제30권3호
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• pp.267-290
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• 2019

본 연구는 학교도서관 전담인력의 전문성 강화를 위한 계속교육에 대한 현황과 실태를 조사하고 계속교육의 개선방안을 제시하는 것을 목적으로 한다. 이를 위하여 경기도 고양지역 초 중 고등학교도서관에 근무하는 사서교사 및 사서 69명을 대상으로 설문조사를 실시하고 빈도분석 및 교차분석을 실시하였다. 연구결과는 다음과 같다. 첫째, 사서교사의 계속교육에 대한 관심과 참여 경험이 높다는 사실을 파악하였다. 둘째, 참여비중이 가장 높은 계속교육 유형은 단기연수 및 강습과정으로 나타났으며, 제공되고 있는 계속교육이 실무와의 연계성이 낮은 것으로 나타났다. 셋째, 관리자의 낮은 인식과 지역적 제약과 적합한 계속교육 프로그램의 부재가 계속교육의 방해요인으로 나타났다. 넷째, 근무시간 중과 방학 중의 계속교육을 선호하며, 다양한 주제의 계속교육 필요성이 강조되었다. 이를 통해 지속적이고 장기적인 계속교육, 계속교육을 독려하기 위한 정책지원, 전문성을 위한 계속교육 과정 개발, 관리자의 인식전환 및 계속교육에 대한 홍보가 필요함을 제안하였다.

• 한국학교보건학회지
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• 제27권3호
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• pp.169-180
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• 2014

Purpose: This study aims to investigate effectiveness in foreign Health Promoting School through a systematic review. Methods: To perform a systematic literature survey, the researcher searched two database (PubMed and Springer Link) for literature relevant to 'health promoting schools' (published up to April 2013 from 2004). The key words used for the search were "effectiveness", "evaluation" and "health promoting school". five evaluations in this review were selected in the peer reviewed. Results: 1. The areas of standardized assessments were dealing with school health policy, physical environment, psycho social environment, community participation, Literacy on health, personal hygienic skills, academic achievement, self reported health status, and mental health. 2. There was evidence that the health promoting school has some positive influence on various domains of assessment. Conclusion: This systematic review provides evidence concerning the effectiveness of the health promoting school.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권4호
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• pp.784-799
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• 2013

This paper presents an adaptive rate control scheme for streaming-based content sharing service. This scheme delivers multimedia contents from a user device to another device or seamlessly redirects streaming service across heterogeneous user devices. In the proposed scheme, a streaming server adjusts video quality level according to the network and client status. Our scheme is different from other rate control schemes, because the video quality at the server is decided not only based on the available bandwidth, but also based on the device characteristics and bandwidth requirement at the access network. We also propose a bandwidth estimation method to achieve more equitable bandwidth allocations among streaming flows competing for the same narrow link with different Round Trip Times (RTTs). Through the simulation, we prove that our scheme improves the network stability and the quality of streaming service by appropriately adjusting the quality of the video stream. The simulation results also demonstrate the ability of the proposed scheme in ensuring RTT-fairness while remaining throughput efficient.

• 제어로봇시스템학회논문지
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• 제7권11호
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• pp.962-966
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• 2001

The major problem at a branch point for point-to-multipoint available bit rate(ABR) services in asynchronous transfer mode (ATM) networks is how to consolidate backward resource management(BRM) cells from each branch for a multicast connection. In this paper, we propose an efficient feedback consolidation algorithm based on an adaptive dynamic threshold(ADT) to eliminate the consolidation noise and the reduce the consolidation delay. The main idea of the ADT algorithm lies in that each branch point estimates the ABR traffic condition of the network through the virtual queue estimation and the transmission threshold of the queue level in branch points is adaptively controlled according to the estimation. Simulation results show that the proposed ADT algorithm can achieve a faster response in congestion status and a higher link utilization compared with the previous works.

• 기술혁신학회지
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• 제8권spc1호
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• pp.337-359
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• 2005

This paper is to analyze the current status and interdependence of knowledge regarding innovation related research in Korea, based on the four academic journals such as Journal of Korea Technology Innovation Society, Journal of Technology Innovation, The Korean Venture Management Review, and Research Policy. The major contributions of this research are as follows: First, we tried to see the general picture of the innovation research community by extending the boundary of analysis, not limiting to a specific journal. Second, instead of subjective and qualitative analysis relying on an expert review, we quantitatively analyzed various basic statistics on innovation area and confirmed that there exist differences for using key words across the journals. Third, we derived a set of influential papers in terms of the authoritative and hub indexes employing link analysis techniques. Finally we provided some recommendations for facilitating knowledge creation activities of academic journals in this area.

• 한국시뮬레이션학회논문지
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• 제3권1호
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• pp.115-124
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• 1994

In this paper, we have developed a performance analysis tool for communication networks called COMNAS. COMNAS analyses the performance of wide area networks such as Korea Educational Network and Korea Research Environment Open Network which include local area networks such as Ethernet and Token Ring. COMNAS consists of model constructor, simulation implementor, output analyzer and user interface. Attributes of communication networks for modeling either have default values or are entered by user as object units, and implementation of simulation is automatically proceeded by user interface. Ouput results obtained by COMNAS are the status of node, link and entire network such as mean message transmission delay, throughput, utilization, and so on, and they can be selectively obtained upon the request of the user.

• 천문학회보
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• 제42권2호
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• pp.38.1-38.1
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• 2017

Symbiotic stars are long-orbital-period interacting binaries characterized by extended emission over the whole electromagnetic range and by complex photometric and spectroscopic variability. In this contribution, I will present some high-cadence, long-term optical light curves of confirmed and candidate symbiotic stars in the Magellanic Clouds. By careful visual inspection and combined time series analysis techniques, we investigate for the first time in a systematic way the photometric properties of these astrophysical objects, trying in particular to distinguish the evolutionary status of the cool component, to provide its first-order pulsation ephemeris and to link all this information with the physical parameters of the binary system as a whole. Finally, I will discuss a new, promising photometric technique, potentially able to discover Symbiotic Stars in the Local Group of Galaxies without the recourse to costly spectroscopic follow-up.

• BMB Reports
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• 제50권9호
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• pp.435-436
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• 2017

Primed human pluripotent stem cells (hPSCs) are highly dependent on glycolysis rather than oxidative phosphorylation, which is similar to the metabolic switch that occurs in cancer cells. However, the molecular mechanisms that underlie this metabolic reprogramming in hPSCs and its relevance to pluripotency remain unclear. Cha et al. (2017) recently revealed that downregulation of SIRT2 by miR-200c enhances acetylation of glycolytic enzymes and glycolysis, which in turn facilitates cellular reprogramming, suggesting that SIRT2 is a key enzyme linking the metabolic switch and pluripotency in hPSCs.