• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.614-618
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• 2002

Although there are a lot of file sharing mechanisms in the Internet such as NFS and P2P, FTP is one of the most common mechanisms used until now. In this paper, we propose a more enhanced file sharing mechanism, the Distributed File Server (DFS) method. The most remarkable feature of DFS is that it can be simply adopted in the current Internet FTP services by locating a DFS node between existing FTP servers and clients without changing any existing file transfer environment. To verify the proposed mechanism we implemented a DFS prototype on RedHat 7.2 system and we finally show that it can reduce the file storage problem caused by big-sized multimedia data.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.441-448
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• 2020

With help of Vehicle-to-Grid(V2G) technology battery in electric vehicle can be used as distributed energy resource and energy storage in a smart grid environment. Several problems of security vulnerability and privacy preservation can be occurred because V2G network supports 2 way communication among all components. This paper explains and makes analysis of architecture, privacy sensitive data, security vulnerability and security requirement of V2G system. Furthermore efficient architecture and operating scheme for V2G system are proposed. This scheme uses symmetric cryptosystem and hash algorithm to support privacy preservation and mutual authentication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.78-81
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• 2004

As a society has Progressed rapidly toward a highly advanced digital information age, a multimedia communication service for acquisition, transmission and storage of image data as well as voice has being commercialized externally and internally. However, in the process of digitalization or transmission of data, noise is generated by several causes, and researches for eliminating those noises have been continued until now. The mean filter is useful method to remove AWGN (additive white gaussian noise) from degraded image and has excellent low-frequency properties. However, it brings about degradation of high-frequency properties in image. So in this paper we removed noise with mean filters added directional information and minimized degradation of high-frequency properties.

• Journal of Internet Computing and Services
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• v.10 no.6
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• pp.219-228
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• 2009

The increased popularity of multimedia applications places a great demand on efficient data storage and transmission techniques. Some methods have been proposed to combine compression and encryption together to reduce the overall processing time, but they are either insecure or intensive computationally. specially, they are unsuitable to wireless communication of mobile device. We propose a novel solution called partial encryption, We introduce quadtree and zerotree wavelet image compression in this paper, it reduces computation for date transmission in mobile device, and does not reduce the compression rate. In conclusion, the proposed partial encryption schemes are fast, secure, and do not reduce the compression performance of underlying compression algorithm.

• Journal of the Korea Computer Industry Society
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• v.9 no.2
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• pp.53-62
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• 2008

Intensive studies have been made in the area of IPTV VOD server. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Buffer utilization, disk performance and network bandwidth. The overlay multicast that has been recently presented as an alternative for the IP multicast has been getting much persuasion by the system resource and the network bandwidth and the advancement of the network cost. we propose a efficient overlay multi_casting network policy for multimedia services with multi media partition storage. Simulation results show that the rate of service number and service time of proposed scheme are about 23% performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.3
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• pp.190-200
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• 2011

Android platform provides a content provider and a cursor mechanism to access the internal SQLite engine. Content providers not only store and retrieve data but also make it accessible to applications. Applications can only share data through content provider, since there's no common storage area that Android packages can access. Cursor is an interface that provides random read-write access to the result set returned by a database query. However, this cursor possesses two major limitations. First, a cursor does not support a join clause among cursors, since the cursor can only access a single table in the content provider. Second, the cursor is not capable of creating user-customized field in the predefined content providers. In this paper, we propose the unified cursor architecture that merges several cursors into a single virtual cursor. Cursor translation look-aside buffer (TLB), column windowing mechanism and virtual data management are the three major techniques we have adopted to implement our structure. And we also propose a delayed synchronization method between an application and a proposed unified cursor. An application can create a user-customized field and sort multiple tables using a unified cursor on Android platform.

• Journal of Convergence for Information Technology
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• v.9 no.9
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• pp.20-26
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• 2019

With the development of ICT technology and the promotion of smartphone penetration, purchasing services that purchase various products through online market are being activated. In particular, due to advances in storage and delivery technology, sales of short food materials can be purchased online. Therefore, in this paper, we propose an integrated solution that enables advertisement effect, ordering and delivery through a purchase service even if there is no sales knowledge and sales network in a small shopping mall where only offline sales can be performed. The proposed system is able to efficiently view the product information by category through image search for the product that the user desires, so that the seller of the registered product can efficiently sell without any additional advertisement.

• The Journal of the Convergence on Culture Technology
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• v.5 no.2
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• pp.367-373
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• 2019

As the number of Battery Electric Vehicle (BEV) is increasing dramatically Vehicle-to-Grid (V2G) te chnology also has been spotlight from industry and academia recently. With help of V2G technology Battery of EV can play many important roles like as energy storage system (ESS) and electric energy resource in Smart Grid environment. This paper provides comprehensive review of Vehicle-to-Home(V2H), Vehicle-to-Building(V2B) and Vehicle-to-Grid(V2G) technologies. The economical analysis of these technologies is also discussed.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.643-646
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• 2009

최근에 IPTV(Internet Protocol TV) 셋톱박스의 보조기억장치의 성능과 저전력을 위한 연구가 많이 수행 되고 있다. IPTV를 위한 셋톱박스의 구성품인 하드디스크는 멀티미디어 데이터를 저장하고 저장된 데이터를 재생한다. 하지만 하드디스크는 기계적인 특성으로 인하여 전력 소모 문제 및 성능 저하 문제 등이 있다. 본 논문에서는 IPTV 환경에서 하드디스크와 플래시 메모리를 혼합한 하이브리드 저장 시스템을 구성 하여 멀티미디어 데이터의 n-프레임을 플래시 메모리로 선반입 하는 새로운 방법을 제안한다. 이 방법을 통해 하드디스크의 대기시간을 줄이고 전력 사용을 최적화 할 수 있다. 실험을 통해 제안한 방법이 기존 방법과 비교하여 20.69%의 평균응답시간을 개선하고 전력소모를 28.14% 감소시킴을 확인 하였다.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.426-439
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• 1999

본 논문에서는 웹(World Wide Web)에서 사용자가 손쉽고 편리하게 이용할 수 있는 멀티미디어 대중교통 안내시스템 개발 경험을 소개한다. 개발된 시스템은 클라이언트와 서버 시스템, 경로탐색 시스템, 교통정보 저장 시스템, 노선 및 정류장 관리 시스템으로 구성되어 있다. 클라이언트에서 작동되는 사용자 인터페이스는 직관적으로 이해가 쉽고, 사용이 편리하며 인터액티브한 멀티미디어 대중 교통안내 서비스를 제공한다. 서버 시스템은 교통정보 수집 시스템으로부터 입력되는 데이타와, 경로탐색 시스템, 교통정보 저장 시스템과 연동되어 클라이언트의 요구사항을 처리하고 그 결과를 사용자에게 돌려준다. 수정된 A* 알고리즘을 이용하는 경로탐색 시스템은 최적경로를 탐색하며, 교통정보 저장 시스템은 현재 교통상황, 정류장, 노선, 지도 등의 정보를 저장한다. 노선 및 정류장 관리시스템은 시스템 관리자가 노선 또는 정류장 관리를 서버 화면의 지도상에서 효율적으로 수행할 수 있는 도구이다. 본 논문에서 다루는 대중교통 안내시스템은 Java로 구현하였기 때문에 확장과 이식이 용이하며, 시스템 유지보수 비용이 적게 드는 장점을 가지고 있다. 그리고, 웹 브라우저가 동작되는 환경에서는 어디서나 쉽게 접근이 가능하며 향후 구축될 Intelligent Transportation Systems(ITS)의 한 모듈로써 바로 작동될 수 있을 뿐만 아니라, 현재 인터넷상에서 제공되는 다양한 서비스와도 연동이 가능하다.Abstract This paper introduces our experience for developing a public transportation guidance system, which facilitates the World-Wide Web(WWW) to provide users with easier access and use. The proposed system is composed of four subsystems: client/server system, path search system, traffic data storage system, and traffic raw-data management system. The user interface in clients utilizes Java to furnish users with multimedia data accessibility and interactivity. The server processes clients' requests based on the traffic data coming from remote sensing devices and interacts with the path search system and traffic data storage system to provide users with the results. The path search system, which uses a modified A* algorithm, produces optimal solutions based on dynamic traffic data. The traffic data storage system stores the current traffic information together with the geographical information about the b$us_way routes. The traffic raw-data management system is a graphical user interface which enables the system manager to handle the traffic information easily on the map in the terminal screen. The system has considerable benefits such as portability, scalability, and flexibility since it is implemented using Java. Also, it can be extended to an integrated Intelligent Transportation Systems(ITS) which includes a variety of information on the Internet as well as traffic information.n.