• Journal of information and communication convergence engineering
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• v.3 no.1
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• pp.56-61
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• 2005

In this paper, we present a video rate control scheme for storage and delivery in which the time-varying viewing interests are controlled by human gaze. To track the gaze, the pupil's movement is detected using the three-step process : detecting face region, eye region, and pupil point. To control bit rates, the quantization parameter (QP) is changed by considering the static parameters, the video object priority derived from the pupil tracking, the target PSNR, and the weighted distortion value of the coder. As results, we achieved human interfaced visual model and corresponding region-of-interest rate control system.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.397-399
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• 2003

CDN(Content Delivery Network)은 기존의 중앙 집중형 구조를 갖는 multimedia streaming 서비스의 서버 과부하 문제와 서버 주위의 네트웍 전송 속도 급감 문제를 해결하기 위해 서버와 클라이언트 사이에 컨텐츠 캐시 역할을 하는 edge server를 둠으로써 원래 서버로의 요청을 분산 처리하는 컨텐츠 전송 기술이다. 그러나 여전히 대규모 전송이 필요할 경우 원하는 수준만큼의 scalability를 보장할 수 없다. 이에 대한 근본적인 해결방법으로 본 논문에서는 P2P 기반의 CDN 시스템 구축을 위한 첫 단계로서 참여 노드간의 네트워크 토폴로지와 전송 성능간의 관계를 분석해보고자 한다. 이를 위해 다양한 구조의 전송 성능을 평가할 수 있는 환경을 구축하였으며 이를 이용하여 설러 구조에서의 전송 성능 측정 결과를 제시하여 최적의 P2P 전송 네트워크를 결정할 수 있도록 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5323-5343
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• 2018

Mobile applications and social networks tend to enhance the need for high-quality content access. To address the rapid growing demand for data services in mobile networks, it is necessary to develop efficient content caching and distribution techniques, aiming at significantly reduction of redundant content transmission and thus improve content delivery efficiency. In this article, we develop optimal cooperative content cache and distribution policy, where a geographical cluster model is designed for content retrieval across the collaborative small cell base stations (SBSs) and replacement of cache framework. Furthermore, we divide the SBS storage space into two equal parts: the first is local, the other is global content cache. We propose an algorithm to minimize the content caching delay, transmission cost and backhaul bottleneck at the edge of networks. Simulation results indicates that the proposed neighbor SBSs cooperative caching scheme brings a substantial improvement regarding content availability and cache storage capacity at the edge of networks in comparison with the current conventional cache placement approaches.

• Archives of Pharmacal Research
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• v.28 no.6
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• pp.736-742
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• 2005

Xyloglucan (XG), which exhibits thermal sol to gel transition, non-toxicity, and low gelation concentration, is of interest in the development of sustained release carriers for drug delivery. Drug-loaded XG beads were prepared by extruding dropwise a dispersion of indomethacin in aqueous XG solution (2 wt.-$\%$) through a syringe into corn oil. Enteric coating of XG bead was performed using Eudragit L 100 to improve the stability of XG bead in gastrointestinal (GI) track and to achieve gastroresistant drug release. Release behavior of indomethacin from XG beads in vitro was investigated as a function of loading content of drug, pH of release medium, and concentration of coating agent. Adhesive force of XG was also measured using the tensile test. Uniform-sized spherical beads with particle diameters ranging from 692 $\pm$ 30 to 819 $\pm$ 50 $\mu$m were obtained. The effect of drug content on the release of indomethacin from XG beads depended on the medium pH. Release of indomethacin from XG beads was retarded by coating with Eudragit and increased rapidly with the change in medium pH from 1.2 to 7.4. Adhesive force of XG was stronger than that of Carbopol 943 P, a well-known commercial mucoadhesive polymer, in wet state. Results indicate the enteric-coated XG beads may be suitable as a carrier for oral drug delivery of irritant drug in the stomach.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.383-394
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• 2023

Purpose : This study focuses on improvements in cell broadcast service(CBS) with consideration of socially vulnerable groups, and identifies service factors necessary for elderly people in particular. Method : Multiple regression analysis was applied to test overall satisfaction with cell broadcast service as the dependent variable and each of the service factors as the independent variable. Result : The results showed that fast delivery had the greatest effect on overall satisfaction with cell broadcast service in both groups, followed by the delivery of sufficient content for the elderly group and system quality for the non-elderly group. The results demonstrated that the elderly group cared more about information content, while the non-elderly group considered functions such as system quality and text message transmission criteria more important. Conclusion : Elderly people consider the delivery of sufficient information important as well as fast delivery, which suggests that it is necessary when sending cell broadcast service to give consideration to the characteristics of elderly people, as they tend to have weaker understanding and thinking abilities than the non-elderly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.818-830
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• 2005

Recently, Peer-to-Peer (P2P) overlay networks like CAN, Chord, Pastry and Tapestry offer a novel platform for scalable and decentralized distributed applications. These systems provide efficient and fault-tolerant routing, object location, and load balancing within a self-organizing overlay network. Content Delivery Network (CDN) is an intermediate layer of infrastructure that helps to efficiently deliver the multimedia content from content providers to clients. In this paper, We propose a topology-aware P2P overlay network for CDN, Rosary, in which CDN servers perform Intra-Pastry and Inter-Pastry routing based on a two-level structured overlay network. This proposed system extends pastry by adapting itself to CDN environments, where a semi-hashing based scheme for Intra-Pastry routing is introduced, and dynamic landmark technology is used to construct the topology-aware overlay network. Through simulations on NS-2, it is shown that Rosary is scalable, efficient, and flexible.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.568-577
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• 2014

We consider a mobile content delivery network (mCDN) in which special mobile devices designated as caching servers (caching-server device: CSD) can provide mobile stations with popular contents on demand via device-to-device (D2D) communication links. On the assumption that mobile CSD's are randomly distributed by a Poisson point process (PPP), an optimization problem is formulated to determine the probability of storing the individual content in each server in a manner that minimizes the average caching failure rate. Further, we present a low-complexity search algorithm, optimum dual-solution searching algorithm (ODSA), for solving this optimization problem. We demonstrate that the proposed ODSA takes fewer iterations, on the order of O(log N) searches, for caching N contents in the system to find the optimal solution, as compared to the number of iterations in the conventional subgradient method, with an acceptable accuracy in practice. Furthermore, we identify the important characteristics of the optimal caching policies in the mobile environment that would serve as a useful aid in designing the mCDN.

• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.399-404
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• 2010

We propose a seamless IPTV transport technology of mobile device. This technology uses multiple interfaces of wireless communication on mobile device. This proposal for transportation of mobile IPTV contents is more mobile and adaptable than other wireless technologies that are currently being used. Algorithm of proposed technology is as follow. When the signal strength of the connected wireless network interface of mobile device is getting lower than specified level, another wireless network interface is connected to continue downloading the IPTV contents in advance. Another connection is maintained until the signal strength of the first connected interface is stable or the interface is connected to another base station (or AP) that have good signal strength. For more seamless services, we consider classifying the packets of mobile IPTV and using dynamic content quality select techniques. Dynamic content quality selection is based on notifying transfer rate to the content delivery network (CDN) server. The proposed technology is expected to use efficiently with both mobile IPTV and the transportation of mobile P2P/P4P.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.404-407
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• 2014

CDN(Content Delivery Network)은 사용자의 콘텐츠 요청에 대해 캐쉬 서버의 부하를 줄이기 위해 사용자와 가장 인접한 캐쉬 서버를 통하여 사용자에게 보다 빠르게 콘텐츠를 제공 하도록 되어있다. 현재까지의 연구는 대용량 콘텐츠 스트리밍 서비스를 위한 속도적 측면만 고려하고 있으며 콘텐츠를 빠르게 제공하기 위하여 같은 콘텐츠를 여러 캐싱서버로 분산하여 보안성이 충분하지 못한 단점이 있다. 하지만 사용자에게 충분한 보안성을 갖춘 대용량 콘텐츠를 제공하려면 암호화 연산의 증가로 인하여, 속도적 측면이 감소하므로 CDN의 본연의 기능을 잃을 수 있다. 그러므로 본 논문에서는 해시기반 스크램블링을 이용한 암호화 기법의 보안의 취약성을 분석하고 이를 극복하기 위해 보안성을 향상시킨 RECOS(Robust Encryption for COntent Secure)기법을 제안한다. 제안 기법은 시뮬레이션에서 기존 기법과 제안 기법의 속도를 비교하였으며, 기존 기법의 취약성 분석을 통하여 제안 기법의 향상된 보안성을 보였다. 결과적으로 기존의 해시기반 암호화 기법과 비교하여 속도에 차이가 거의 없음에도 불구하고 향상된 보안성을 보였다.

• Journal of the Korean Applied Science and Technology
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• v.27 no.4
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• pp.407-414
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• 2010

New biological treatments were being developed at a record place, but their potential could be compromised by a significant obstacle: the delivery of these drugs into a body. Pharmaceutical delivery is now nearly as important as product. New systems are being developed, and Drug Delivery Markets Series cover these new systems. Transdermal Delivery System(TDS) is often used as a method of drug dosage into the epidermic skin. An approach used to delivery drugs through the skin for therapeutic use as an alternative to oral, intravascular, subcutaneous and transmucosal routes. Various transdermal drug delivery technologies are described including the use of suitable formulations, carriers and penetration enhancers. The most commonly used transdermal system is the skin patch using various types of technologies. Compared with other methods of dosage, it is possible to use for a long term. It is also possible to stop the drug dosage are stopped if the drug dosage lead to side effect. Polysaccharides, such as karaya gum and glucomannan, were selected as base materials of TDS. Also, these polymers were characterized in terms of enhancers, drug contents. Among these polysaccharide, the permeation rate of karaya gum matrix was fastest in fibric acid(ciprofibrate) such as lipophilic drug in vitro. We used glycerin, PEG400 and PEG800 as enhancers. Since dermis has more water content(hydration) than the stratum corneum, skin permeation rate at steady state was highly influenced when PEG400 was more effective for lipophilic drug. Proper selection of the polymeric materials which resemble and enhance properties of the delivering drug was found to be important in controlling the skin permeation rate. Especially, this result suggests a possible use of polysaccharide gel ointment matrix as a transdermal delivery system of anti-hyperlipoproteinemic agent.