• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.30-35
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• 2004

모바일 환경에서 브로드캐스트는 그 확장성 때문에 매우 유용한 데이터 전송 방법이다. 'push-based' 데이터 전송 방식에서 서버는 넓은 대역폭을 통해 클라이언트에게 다양한 데이터를 반복적으로 브로드캐스트 한다. 〔1,2〕 브로드캐스트에 기반을 둔 정보 시스템의 데이터간의 연관성에 관한 연구는 미흡한 실정이다. 상호 연관 데이터의 브로드캐스트에서, 클라이언트는 자연스럽게 상호 연관된 데이터의 집합을 요청하게 되며, 데이터의 상호 연관성을 고려할 때 기존의 스케줄링 및 캐싱 기법 등은 달라져야 한다. CBS〔3〕에서는 모든 데이터간의 연관도를 계산하여 최소 비용 경로를 구해, 이 순서대로 브로드캐스트하는 기법을 제안하였다. CBS 기법은, 클라이언트가 연관된 데이터를 동시에 요청하지 않고, NP-문제인 최소 비용 경로를 많은 데이터에 대해서 실시간에 계산해야 되며, 데이터 아이템간의 상호 연관성이 클라이언트마다 다르게 정의되는 문제점이 있다. 따라서 본 논문에서는 응답 시간을 줄이기 위해, 브로드캐스트 되는 상호 연관 데이터의 prefetching기법을 제안한다, 제안된 CT 기법은 상호 연관도와 브로드캐스트 대기시간을 고려하여 캐시를 관리한다. CT를 현실적으로 적용한 ACT의 알고리즘을 소개하였으며, 시뮬레이션을 통해 CT의 성능과 특징을 실험하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.506-515
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• 2015

In this paper, we propose a group playback synchronization method using adaptive synchronization delay time by the bit rate of media to synchronize a play position of streaming media between mobile smart devices. This method consists of streaming server-side and client-side synchronization algorithms based on synchronization delay time which includes connection time, control packet transmission time, streaming data buffering time, and synchronization processing time. We implement the Android media player application with synchronization support using the proposed algorithms and present the result of performance evaluation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.63-71
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• 2006

In this paper, we propose a secure solution for user authentication by using fingerprint verification on the sensor-client-server model, even with the client that is not necessarily trusted by the sensor holder or the server. To protect possible attacks launched at the untrusted client, our solution makes the fingerprint sensor validate the result computed by the client for the feature extraction. However, the validation should be simple so that the resource-constrained fingerprint sensor can validate it in real-time. To solve this problem, we separate the feature extraction into binarization and minutiae extraction, and assign the time-consuming binarization to the client. After receiving the result of binarization from the client, the sensor conducts a simple validation to check the result, performs the minutiae extraction with the received binary image from the client, and then sends the extracted minutiae to the server. Based on the experimental results, the proposed solution for fingerprint verification can be performed on the sensor-client-server model securely and in real-time with the aid of an untrusted client.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.526-528
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• 2004

메타데이타에 대한 접근이 특정 디렉토리에 집중되며 메타데이타 연산마다 다른 계산량을 가지는 클러스터 파일 시스템의 특성상 메타데이타 서버 간 부하의 불균형과 과부하가 발생한다. 따라서 클러스터 파일 시스템의 성능을 결정짓는 중요 요소인 메타데이타 서비스의 성능을 위해서는 메타데이타 서버들의 과부하 상황에 대처할 수 있는 합리적인 부하 분산 기법이 필수적이다. 메타데이타 공간을 분할하여 담당영역만을 관리하는 비대칭 메타데이타 서버를 위해 본 눈문은 클라이언트 요청의 내용을 분석하여 담당 메타데이타 서버를 결정하고 해당 연산의 종류에 따라 단순 검색, 메타데이타 중복 저장(replication), 또는 메타데이타에 대한 로깅(logging)을 수행하는 내용 기반의 부하 분산 알고리즘을 제시하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.1
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• pp.3-14
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• 1999

In this paper, the Client-Server authentication system is proposed and implemented using the smart card on the internet. Based on the MPCOS-3DES smart card manufactured by GEMPLUS, three phases of authentication using the challenge-response mechanism are performed, which includes user-card authentication, client-server authentication, and card-server authentication.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.69-79
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• 2003

Existing large-scale complex programs usually reside In a single computer, and the user has to be physically in contact with the computer. With the wide spread use of the internet, the need to carry out the design and analysis tasks geographically away from the main computer is increasing. In this paper existing Windows-based propeller design and analysis package is separated into the server-client modules and the protocol program is developed to implement the communication between multi-client computers and a single server computer. A new protocol packet is designed to use the Windows socket and the server/client programs control the receive/send operations using the information transmitted in the packet. Test runs show that the remote user, connected to the server computer through the internet only, can perform the required tasks.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.123-127
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• 2004

The present system of medium and large size ship when that's ship came alongside the pier, are not systemic. The steersman only depend on radio-communication, not visuality. This treatise bridge a gap of current system from development of simulation program The main-server get a distance from ship to peer and ship's direction using longitude and latitude, heading, rate. The steersman of main ship and tug will see all situation with PDA client program. The PDA client program directly display a location information from main-server. And ship's most suitable path be calculated simulation program using database system. This method will induce more detail situation information and the most suitable path when the ship coming alongside the pier.

• Journal of radiological science and technology
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• v.28 no.4
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• pp.317-325
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• 2005

The recent medical treatment guidelines and the development of information technology make hospitals reduce the expense in surrounding environment and it requires improving the quality of medical treatment of the hospital. That is, with the new guidelines and technology, hospital business escapes simple fee calculation and insurance claim center. Moreover, MIS(Medical Information System), PACS(Picture Archiving and Communications System), OCS(Order Communicating System), EMR(Electronic Medical Record), DSS(Decision Support System) are also developing. Medical Information System is evolved toward integration of medical IT and situation si changing with increasing high speed in the ICT convergence. These changes and development of ubiquitous environment require fundamental change of medical information system. Mobile medical information system refers to construct wireless system of hospital which has constructed in existing environment. Through RFID development in existing system, anyone can log on easily to Internet whenever and wherever. RFID is one of the technologies for Automatic Identification and Data Capture(AIDC). It is the core technology to implement Automatic processing system. This paper provides a comprehensive basic review of RFID model in Korea and suggests the evolution direction for further advanced RFID application services. In addition, designed and implemented DB server's agent program and Client program of Mobile application that recognized RFID tag and patient data in the ubiquitous environments. This system implemented medical information system that performed patient data based EMR, HIS, PACS DB environments, and so reduced delay time of requisition, medical treatment, lab.

• The KIPS Transactions:PartC
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• v.10C no.7
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• pp.891-898
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• 2003

This paper analyzes and proposes a scheme that improves the performance of the RTP that is developed to support the end-to-end transmission function and QoS monitor function for real-time multimedia data transmission. Although the existing RTP module supports real-time transmission, it has some problems in guaranteeing QoS parameters. To solve this problem, we propose a new Selective Repeat Adaptive Rate Control (SRARC). The SRARC can support QoS by referring to the data transmission status from the client and then classifying the network status into three levels. It selectively transmits multimedia data and dynamically controls transmission rates based on such information as bandwidth, packet loss rate, and latency that can be calculated in data transfer phase. To verify the SRARC, we implement it in real local area networks and compare the QoS parameters of the SRARC with those of the SR and RTP By the experimental results, the SRARC shows better performance in the aspects of bandwidth usage rate, packet loss rates, and transmission delays than the existing RTP schemes.