• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1065-1085
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• 2020

With rapid growth of content demands, device-to-device (D2D) content sharing is exploited to effectively improve the service quality of users. Considering the limited storage space and various content demands of users, caching schemes are significant. However, most of them ignore the influence of the asynchronous content reuse and the selfishness of users. In this work, the user preferences are defined by exploiting the user-oriented content popularity and the current caching situation, and further, we propose the social-aware rate, which comprehensively reflects the achievable contents download rate affected by the social ties, the caching indicators, and the user preferences. Guided by this, we model the collaborative caching problem by making a trade-off between the redundancy of caching contents and the cache hit ratio, with the goal of maximizing the sum of social-aware rate over the constraint of limited storage space. Due to its intractability, it is computationally reduced to the maximization of a monotone submodular function, subject to a matroid constraint. Subsequently, two social-aware collaborative caching algorithms are designed by leveraging the standard and continuous greedy algorithms respectively, which are proved to achieve different approximation ratios in unequal polynomial-time. We present the simulation results to illustrate the performance of our schemes.

• 천문학논총
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• 제21권1호
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• pp.1-9
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• 2006

An archiving system designed to enable documenting database of astronomical images, with functions of search and download, is being developed by Korean Astronomical Data Center(KADC) of Korea Astronomy and Space Science Institute(KASI). The system consists of three PCs for web server, database server, and system management server. The search program for the web environment is operated in the web server. In the management server, several utility program we developed are installed: input program for the database, program for transfer from fits to jpg files, program for data recovery and management, and programs for statistics and connect management. The collected data would be sorted out by the system manager to input into the database. The online input is possible in an observatory where the data is produced. We applied the content management system(CMS) module for the database management. On the basic of CMS module, we set up a management system for the whole life cycle of metadata from creation and collection to storage and deletion of the data. For the search function, we employed a technique to extract indices from the metadata. In addition, MySQL is adopted for DBMS. We currently display about 2,700 and 25,000 photographs for astronomical phenomena and astronomical objects on the data, respectively.

• 한국전자통신학회논문지
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• 제3권4호
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• pp.240-246
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• 2008

본 논문에는 P2P 환경의 DRM 시스템을 개선하여 분산컴퓨팅의 성능을 최대화하고 사용자 증가와 콘텐츠 공유의 증가에 비례해 발생되는 부하를 최소화함으로써 디지털 콘텐츠의 스트리밍 서비스를 개선하고자 하였다. 이를 위해 인증 프로토콜과 라이센스 프로토콜을 개선하여 콘텐츠를 사용하고자 할 경우 라이선스만을 다운로드 받은 다음 복호화와 실행을 동시에 수행하도록 함으로써 기존 DRM 시스템보다 한층 강화된 스트리밍 지원을 하도록 하였다. 성능 평가를 위해 암호화되어 있는 영상 데이터 파일의 복호화를 먼저 수행한 후 재생하는 기존의 방식과 실시간으로 복호화를 하면서 재생하는 개선된 방식을 비교하여 수행 시간을 측정하였다. 수행 결과 개선된 DRM 시스템이 보다 안정된 대역폭을 유지하고 있으며 지연 시간은 감소하는 것을 확인할 수 있었다.

• 산업공학
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• 제18권3호
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• pp.253-267
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• 2005

Customer satisfaction becomes one of the important managerial concerns associated with corporate competency in current competitive environment for Internet communication service companies. Hence, it is demanding to improve a company's customer satisfaction through the total quality management perspective. In practice, engineers as well as the management hope to find major quality characteristics with Internet communication network that is closely related to customer satisfaction, consequently aiming to the raise of their company's customer satisfaction. This paper presents an empirical relationship analysis between network quality characteristics and customer satisfaction on Internet communication. Methodologically, the relationship analysis framework is based on the regression variable selection procedures. In this framework, it is implemented that; 1) iterative model building; and 2) consistent criteria application to statistical tests for selecting significant variables. A case study shows that; 1) the customer satisfaction on the network connection seems to be more closely related to the network quality characteristics compared with the customer satisfaction on the network speed; and 2) the download disconnection rate has relatively evident relationship with the customer satisfaction on the network connection.

• Smart Structures and Systems
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• 제21권5호
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• pp.611-621
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• 2018

Compared with the highway bridges, the relatively higher requirement on the safety and comfort of vehicle makes the high-speed railway (HSR) bridges need to present enhanced dynamic performance. To this end, installing a health monitor system (HMS) on selected key HSR bridges has been widely applied. Typically, the HSR takes fully enclosed operation model and its skylight time is very short, which means that it is not easy to operate the acquisition devices and download data on site. However, current HMS usually involves manual operations, which makes it inconvenient to be used for the HSR. Hence, a HMS named DASP-MTS (Data Acquisition and Signal Processing - Monitoring Test System) that integrates the internet, cloud computing (CC) and virtual instrument (VI) techniques, is developed in this study. DASP-MTS can realize data acquisition and transmission automatically. Furthermore, the acquired data can be timely shared with experts from various locations to deal with the unexpected events. The system works in a Browser/Server frame so that users at any places can obtain real-time data and assess the health situation without installing any software. The developed integrated HMS has been applied to the Xijiang high-speed railway arch bridge. Preliminary analysis results are presented to demonstrate the efficacy of the DASP-MTS as applied to the HSR bridges. This study will provide a reference to design the HMS for other similar bridges.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2004년도 춘계 종합학술대회 논문집
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• pp.522-528
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• 2004

이동통신망 진화와 함께 다기능 단말기를 기반으로 한 무선인터넷 서비스가 활성화되고 있다. 무선인터넷 서비스는 브라우저 기반의 정보서비스와 다운로드 플랫폼을 사용하는 이동멀티미디어 서비스가 제공되고 있다. 다기능 단말기보급이 확산됨에 따라 이를 기반으로 한 신규서비스 개발이 활발하게 이루어지고 있다. 본 논문은 무선인터넷 서비스에서 핵심서비스로 발전할 위치기반 서비스를 위한 모발일 맵 브라우저로, 개발된 맵 브라우저는 국내 무선인터넷 플랫폼인 WIPI를 사용하여 GIS 서버와 연동하여 지도정보를 제공한다. 또한 개발된 시스템은 위치정보 서비스 이외에 텔레메틱스를 위한 GIS 플랫폼으로 사용되고, 향후 WIPI 플랫폼 확산과 더불어 PDA, 텔레메틱스 단말기 등에서도 서비스가 가능할 것이다.

• International Journal of Contents
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• 제6권3호
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• pp.10-14
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• 2010

Researchers in Korea and elsewhere have carried out a wide variety of important research activities in their respective fields, producing valuable research results. For such diverse research results to be shared and exchanged among researchers working in the same discipline and research subject there needs to be a community environment based on free utilization of information. Against this backdrop, this study seeks to classify and reprocess the reference/factual content owned by the KISTI (Korea Institute of Science and Technology Information), a state-run distributor of information on science and technology, by the different research subjects. It also seeks to develop and provide a community model based on the concepts of open archiving and open access for the researchers specialized in the related fields of research. This community model is developed focusing on the research results from the field of bioscience, where the most extensive studies are currently being conducted. To develop the community model, this study: (a) surveys the current status of the content owned by KISTI; (b) analyzes the patterns and characteristics of biological scientific content among the KISTI-owned content; and (c) designs a web platform where researchers can freely upload/download research results.

• 한국경영과학회지
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• 제37권3호
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• pp.57-68
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• 2012

The recent proliferation of various smart devices like the smartphone, tablet PC, and smart TV enables consumers to download various applications from the network and to access private files stored in their desktop server at any time and at any place. The trend of ubiquitous access seems to have become stronger and more diversified toward a ubiquitous network computing environment with the aggressive deployment of commercial cloud services. Recently, many Korean network service providers launched commercial B2C public cloud services, which were widely adopted by smart device users. They include Daum cloud, N drive, ucloud, and uplus box, mostly provided by major Korean telecom companies and portals. This paper aims to explore consumers' adoption behaviors toward the B2C public cloud services that were recently deployed in the Korean market. In order to achieve the goal, we identified key influencing factors that affect the consumers' adoption behaviors, based on an extension of the technology acceptance model (TAM). Several hundred smart device users were surveyed to test the generic regression model with the extended set of TAM variables.

• 한국멀티미디어학회논문지
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• 제8권5호
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• pp.721-728
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• 2005

가상 기계란 하드웨어로 이루어진 물리적 시스템과는 달리 소프트웨어로 제작되어 논리적인 시스템 구성을 갖는 개념적인 컴퓨터이다 임베디드 시스템을 위한 가상 기계 기술은 모바일 디바이스나 디지털 TV 등의 다운로드 솔루션에 꼭 필요한 소프트웨어 기술이다 현재 EVM(Embedded Virtual Machine)이라 명명된 임베디드 시스템을 위한 가상 기계에 대한 연구가 진행 중이다 이러한 연구의 일환으로 본 논문에서는 임베디드 시스템을 위한 파일 포맷인 EFF(Executable File Form기)로 정의한다. 또한 기존에 널리 사용되고 있는 클래스 파일을 EFF에 매핑 시킴으로써 EFF의 완전성을 구조적으로 증명한다.

• 정보처리학회논문지D
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• 제10D권7호
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• pp.1177-1188
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• 2003

본 논문에서는 H.323 표준을 만족하는 게이트키퍼와 웹 서비스를 이용한 멀티미디어 회의 사이버 공간을 설계하고, 구현한다. 본 논문에서 구현된 게이트키퍼는 H.323 영상회의용 단말기들의 등록 및 호 제어 관리를 담당하며, 웹 서비스를 이용하여 디렉토리 서비스를 제공함으로써 등록된 사용자의 효율적 관리를 가능하게 한다. 또한, 웹에서의 컨트롤 자동 다운로드 기능을 통하여 영상회의 시스템 소프트웨어의 유지 보수를 사용자가 아닌 서비스 공급자가 직접 설정하게 함으로써 보다 향상된 영상회의 시스템의 관리 방법을 제공한다. 마지막으로 디렉토리 서비스의 다양한 응용을 통한 영상회의 서비스의 활용 방안을 제시한다.