• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 가을 학술발표논문집 Vol.30 No.2 (1)
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• pp.589-591
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• 2003

현재 대부분 e-Learning에서 이루어지고 있는 교육은 학습(Loaming)이 아닌 단순 훈련(Trainning)만이 이루어지고 있다. e-Learning에서 진정한 학습이 이루어지기 위해서는 학습자의 수준에 맞는 적응적(Adaptive), 적시적(Just-in-Time) 학습이 단편적이 아닌 연속적, 통합적으로 이루어져야 한다. 이를 위해서는 기술적 관점뿐만 아니라, 발견적 학습(heuristic learning)관점에서 학습자원이 기술되고, 컴퓨터(에이전트)가 학습자원의 구성요소인 학습목표(Goal), 학습내용(Content), 학습맥락(Context), 학습구조(Structure), 학습전략(Strategy)의 의미(Semantic)와 관계(Relation)를 이해해 학습자에게 필요한 정보만을 검색, 추론해주고 이를 학습자 수준에 맞게 재가공해 학습자에게 지식(Knowledge)을 적응적(Adaptive), 적시적(Just-in-Time)으로 전달해주는 e-Learning 학습 환경이 필수적이다. 메타데이터(RDF), 온톨로지(Ontology), 에이전트(Agent) 매커니즘의 시멘틱 웹을 e-Learning 환경에 적용함으로써 학습자원의 구성요소의 의미와 관계를 파악해 적응적(Adaptive)으로 지식을 전달해 주어 자기 주도적 학습(Self-directed Loaming)을 실현해 줄 수 있다.

• Journal of Communications and Networks
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• 제16권3호
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• pp.322-334
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• 2014

Multimedia content is very sensitive to packet loss and therefore multimedia streams are typically protected against packet loss, either by supporting retransmission requests or by adding redundant forward error correction (FEC) data. However, the redundant FEC information introduces significant additional bandwidth requirements, as compared to the bitrate of the original video stream. Especially on wireless and mobile networks, bandwidth availability is limited and variable. In this article, an adaptive FEC (A-FEC) system is presented whereby the redundancy rate is dynamically adjusted to the packet loss, based on feedback messages from the client. We present a statistical model of our A-FEC system and validate the proposed system under different packet loss conditions and loss probabilities. The experimental results show that 57-95%bandwidth gain can be achieved compared with a static FEC approach.

• IEIE Transactions on Smart Processing and Computing
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• 제4권4호
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• pp.231-236
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• 2015

In this paper, the technical analysis and characteristics of screen content coding (SCC) based on High efficiency video coding (HEVC) are presented. For SCC, which is increasingly used these days, HEVC SCC standardization has been proceeded. Technologies such as intra block copy (IBC), palette coding, and adaptive color transform are developed and adopted to the HEVC SCC standard. This paper examines IBC and palette coding that significantly impacts RD performance of SCC for screen content. The HEVC SCC reference model (SCM) 4.0 was used to comparatively analyze the coding performance of HEVC SCC based on the HEVC range extension (RExt) model for screen content.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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• pp.4585-4603
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• 2015

Video streaming services make up a large proportion of Internet traffic on both fixed and mobile access throughout the world. Adaptive streaming allows for dynamical adaptation of the bitrate with varying network conditions, to guarantee the best user experience. Adaptive bitrate algorithms face a significant challenge in correctly estimating the throughput as it varies widely over time. In this paper, we first evaluate the throughput estimation techniques and show that the method that we have used offers stable response to throughput fluctuations while maintaining a stable playback buffer. Then, we propose an adaptive bitrate scheme that intelligently selects the video bitrates based on the estimated throughput and buffer occupancy. We show that the proposed scheme improves viewing experience by achieving a high video rate without taking unnecessary risks and by minimizing the frequency of changes in the video quality. Furthermore, we show that it offers a stable response to short-term fluctuations and responds swiftly to large fluctuations. We evaluate our algorithm for both constant bitrate (CBR) and variable bitrate (VBR) video content by taking into account the segment sizes and show that it significantly improves the quality of video streaming.

• 한국의류산업학회지
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• 제13권1호
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• pp.17-24
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• 2011

This study aims to provide basic materials for adaptive-clothing development for disabled seniors by considering the characteristics of design with both functionality and beauty, which is displayed to overseas functional clothing for disabled seniors. After 341 photographs from 15 overseas websites which sold adaptive-clothing for disabled seniors were collected, their designs were analyzed. The content analysis and frequency analysis using the descriptive statistics were performed as the analytical methods for this study. The results are as follows; first, the design of buttons uses snap fasteners, zippers, Velcro fasteners and rubber bands so as to attach easily and keep fasteners unseen. Second, the used open system is the Back open, the Side open, the Front open and the Hip open. Third, in terms of design, the change follows easy and loose silhouette in order to act comfortably outdoors as well as indoors by making the design of onepiece dresses, jackets and cardigans similar to ordinaries. From the details aspect, a few trimmings such as color, patterns, ruffles around edge, laces and smooth shirring do not stand in the way and give mental please.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3804-3819
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• 2018

The increasing popularity of HTTP adaptive video streaming services has dramatically increased bandwidth requirements on operator networks, which attempt to shape their traffic through Deep Packet inspection (DPI). However, Google and certain content providers have started to encrypt their video services. As a result, operators often encounter difficulties in shaping their encrypted video traffic via DPI. This highlights the need for new traffic classification methods for encrypted HTTP adaptive video streaming to enable smart traffic shaping. These new methods will have to effectively estimate the quality representation layer and playout buffer. We present a new machine learning method and show for the first time that video quality representation classification for (YouTube) encrypted HTTP adaptive streaming is possible. The crawler codes and the datasets are provided in [43,44,51]. An extensive empirical evaluation shows that our method is able to independently classify every video segment into one of the quality representation layers with 97% accuracy if the browser is Safari with a Flash Player and 77% accuracy if the browser is Chrome, Explorer, Firefox or Safari with an HTML5 player.

• 전기학회논문지
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• 제66권3호
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• pp.575-580
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• 2017

In these days, the big-size and high resolution multimedia file is widely used through networks. To transfer and service effectively, the internet network technology is necessary to substitute broadcasting. Normally Content Delivery Network(CDN) is widely used in conventional internet for multimedia services. But it has a small bandwidth to service. So to solve this problems, many researchers have suggest the protocol for download, content distribution/saving, server synchronization, caching, pushing rate, and streaming etc. But all of these has some defects like low resolution, packets loss and delay, real application implementations etc. So, this paper suggests a new method of network protocol based on P2P collaboration and user's content using information. And it evaluated the performance of suggested method. As the results, it showed the effectiveness of 4 performances indices : download speed, decreasing rate of connected user in same time, adaptive hit ratio, traffic decreasing rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.5074-5094
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• 2016

Screen splitting is one of the fundamental tasks in different methods including video and image compression, screen classification, screen content coding and the like. These methods in turn support various applications in data communications, remote screen sharing, remote desktop delivery to assist teaching-learning, telemedicine, Desktop as a Service etc. In the literature we find systems requiring splitting assumes a fixed size split that do not change dynamically, also there is no analysis why that split is chosen in terms of performance. By doing mathematical analysis this paper first finds the efficient splitting schemes that can be easily automated to make a system adaptive. Thereafter, taking the screen motion detection as a case study, it demonstrates the effects of various splitting methods on motion detection performance. The simulation results clearly shows how classification performances varies with different splitting which will facilitate to choose the best splitting for a specific application scenario as well as making the system adaptive by providing dynamic splitting.

• 한국환경복원기술학회지
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• 제16권1호
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• pp.83-97
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• 2013

This study was carried out to suggest an experimental base in selecting the drought resistance of plants. Adopting the natural drought method, this paper studies the drought resistance of 12 kinds of ground cover plants. focusing on analyzing the changes of relative water content on leaf, relative electric conductivity and chlorophyll content in 12 kinds of plants, and and the relation between soil water content under drought stress. The drought resistance of the plants were subject to laboratory and rooftop drought resistance treatments. The Logistic model of nonlinear regression analysis was used to evaluate the lethal time that were predicted with the range of 10.4~30.1d on roof top, and 19.5~39.0d on hothouse. The result shows that with the increase of stress time, relative water content and chlorophyll content on leaf were in a downward trend; the relative electric conductivity was upward tendency. Among 12 species of ground cover plants, exclude Pulsatilla koreana, Ainsliaea acerifolia were selected for rooftop plants because they showed resist drought strongly and took adaptive ability.

• 한국멀티미디어학회논문지
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• 제6권7호
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• pp.1149-1158
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• 2003

본 논문에서는 멀티웨이브릿 변환영역에서 연속부대역 양자화 및 지각 모델을 이용한 내용기반 적응적 워터마킹 기법을 제안한다. 제안한 방법의 워터마크는 멀티웨이브릿을 통해 분해된 계수들 중 지각적 중요계수(perceptually significant coefficients, PSCs)에 삽입된다. 고주파 부대역에서의 PSC는 연속부대역양자화(successive subband quantization, SSQ)에 의해 결정된다. 문턱값은 각 부대역내의 최대계수의 절반에서 결정된다. 지각모델은 워터마크 삽입을 위한 국부적 영상 특성을 가지는 NVF (noise visibility function)에 기반한 통계적 방법을 적용한다. 이 모델은 워터마크가 노이즈특성을 가지므로 정상상태 일반화 가우스모델을 사용한다. 또한 워터마크는 각 부대역 영역의 분산과 형상계수 (shape parameter)에 의해 추정함으로써 평탄영역과 에지나 텍스쳐 영역에 따라 내용 기반 적응적 척도를 얻는다. 제안한 멀티웨이브릿 변환 기반에서의 워터마크 삽입 방법에 대한 실험 결과 우수한 강인성과 비가시성을 확인하였다.