• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.913-921
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• 2012

On the strength of the rapid development and propagation of U-healthcare service, the service technologies are full of important changes. However, U-healthcare service has security problem that patient's biometric information can be easily exposed to the third party without service users' consent. This paper proposes a distributed model according authority and access level of hospital officials in order to safely access patients' private information in u-Healthcare Environment. Proposed model can both limit the access to patients' biometric information and keep safe system from DoS attack using time stamp. Also, it can prevent patients' data spill and privacy intrusion because the main server simultaneously controls hospital officials and the access by the access range of officials from each hospital.

• Korean Journal of Remote Sensing
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• v.30 no.4
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• pp.445-454
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• 2014

In recent days, trend technologies for cloud, bigdata, or mobile, as the important marketable keywords or paradigm in Information Communication Technology (ICT), are widely used and interrelated each other in the various types of platforms and web-based services. Especially, the combination of cloud and mobile is recognized as one of a profitable business models, holding benefits of their own. Despite these challenging aspects, there are a few application cases of this model dealing with geo-based data sets or imageries. Among many considering points for geo-based cloud application on mobile, this study focused on a performance test of mobile cloud of Bayesian image fusion algorithm with satellite images. Two kinds of cloud platform of Amazon and OpenStack were built for performance test by CPU time stamp. In fact, the scheme for performance test of mobile cloud is not established yet, so experiment conditions applied in this study are to check time stamp. As the result, it is revealed that performance in two platforms is almost same level. It is implied that open source mobile cloud services based on OpenStack are enough to apply further applications dealing with geo-based data sets.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.2
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• pp.88-96
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• 2008

IPTV Content delivery systems over wired networks confront scalability problems due to their high network bandwidth requirement for real-time services. Especially, VoD service provides Trick Mode features such as pause, fast forward and similar operations. However, Trick Mode services are delivered by the method of unicast only for controlling of the stream. With a point of views, this paper propose a new real-time multimedia streaming architecture over IP Networks, which tries to achieve bandwidth efficiency and supporting for mass clients better than traditional unicast services. The proposed methods divide the Transport Stream into a series of segments. After that, this divided partial Transport Stream makes multicast streaming periodically. Meanwhile Set-top Box of a client makes a rearrangement orderly by using Presentation Time Stamp field from the served Transport Stream packets. While the current Transport Stream segment is playing, it should be guaranteed that the next segment is downloaded on time. Consequently, the original video content can be played out continuously. The detail introduction of a new real-time multimedia streaming system with analysis and simulation follows as below.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1403-1410
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• 2005

The synchronization problem is directly related to the quality of service in multimedia communication and especially in real-time communication. In this study, we found the cause of clock fluctuation between encoder and decoder in MPEG-2 system layer was that the standard decoder design only considered a fixed time delay component. To solve it, we proposed Extended-SRTS algorithm, which uses STC as service clock by synchronizing transport stream. As the result, we can improve the effect of frequency-drift, time-varying-network-jitter and packing-jitter and so on And by virtue of this algorithm, we can make low the dependency of network clock, which makes easy to synchronize and connect transparently at the ends point, we expect the proposed algorithm can be widely applied to the field of real -time multimedia communications.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.351-358
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• 2002

Recently, personal business styles have been rapidly changed into e-business due to the rapid progress and deployment of Internet. As a result of the change, new and safe ways of payment such as electronic wallet, electronic money and electronic check have been developed and introduced. In this paper a secure and user-friendly payment method is addressed. One of most important reasons why newly developed safe payment methods are not widely used in e-business is lack of convenience for the users. On the other hand credit card based payment, which is traditional one, is the most prevailing due to the user-friendliness. However this payment also has some problem in sense of security. In this paper, we design and implement a secure credit card-based payment system using one-time credit information. The main features are "payment information must be new", "can use the old credit system", and "do not require client software".

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.4 s.23
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• pp.58-67
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• 2005

To overcome limitations of test scope, schedule and cost, M&S(Modeling & Simulation) technique has been applied for T&E(Test and Evaluation) of the state-of-art weapon systems. This paper proposes an air defense simulation software framework to reduce both redundancy an[1 programming errors in system simulator. The proposed framework consists of a 'model' and a 'middleware' The 'middleware' is a reliable communication service layer that supports not only HLA(High Level Architecture) which is an international standard in M&S but also TCP/IP, UDP and etc. The main role of 'model' is to schedule and to run the real-time distributed simulation. The proposed framework has been applied to M-SAM(Middle range Surface to Air Missile) system simulator. The proposed framework's scheduling and communication performance results are satisfactory and were measured by hardwired NTP(Network Timer Protocol) time-stamp with GPS(Global Positioning System) timer for better precision.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1631-1634
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• 2002

멀티미디어 서버는 클라이언트가 요청한 멀티미디어 데이터 스트림을 효율적으로 제공하기 위해 사용된다. 현재, 정보통신 기술의 발달로 인해 멀티미디어 서버는 멀티미디어 정보를 온라인으로 서비스 할 수 있게 되었다. 하지만 네트워크 상에서 발생하는 Packet Delay 에 때문에 서버에서 사용자에게 연속적이고 엄격한 실시간 제약이 있는 비디오 전송과 같은 멀티미디어 서비스를 제공하는 것은 매우 힘들다. 따라서, 본 논문에서는 서버에서 필요한 Packet 를 먼저 전송하여 Packet Delay 를 줄이는 방법을 제안하였다. MPEG-4 에서 오브젝트의 AU(Access Unit)들의 디코딩 시간을 표시하는 DTS(Decoding Time Stamp)를 참조하여 생성된 Deadline threshold 를 기준으로 Deadline 이 가장 빠른 AU부터 전송하는 스케줄링 알고리즘을 이용하여 MPEC-4 미디어 오브젝트를 스트리밍한다.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.821-828
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• 2013

This paper proposed CHELS-App that Smart-phone APP optimized cultural heritage experiential learning is configured can learning and sightseeing at the same time with experience the cultural heritage and enjoying the mission through quests to take advantage of the Smart-phone. CHELS-App is provide a guide maps by using the location-based service and cultural commentary(commentary, photos, quizzes, games, cartoon) with capability of event push about the Jongmyo Shrine as world heritage, and configured with capability of experience diary create and foot stamp through these experiences.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1453-1460
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• 2014

WFQ (Weighted Fair Queuing) provides not only fairness among traffic flows in using bandwidth but also guarantees the Quality of Service (QoS) that individual flow requires, which is why it has been applied to the resource reservation protocol (RSVP)-capable router. The RSVP allocates an enough resource to satisfy both the rate and end-to-end delay requirements of the flow in the condition of no packet loss, and the WFQ scheduler guarantees those QoS requirements with the allocated resource. In practice, however, most QoS-guaranteed services allow a degree of packet loss, especially from 0.1% to 3% for Voice over IP. This paper discovers that the packet loss rate of each traffic flow is determined by only its time-stamp adjustment value, and then enhances the WFQ to provide a differentiated packet loss guarantee under general traffic conditions in terms of both traffic characteristics and QoS requirements. The performance evaluation showed that the proposed WFQ could increase the utilization of bandwidth by 8~11%.

• The Transactions of the Korea Information Processing Society
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• v.3 no.2
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• pp.295-304
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• 1996

Toprovide economical BISDN service, with which integration process of many types of media is possible, it is necessary to construct a system with ground network and satellite network combined. The method for this type of transmission using satellite is TDMA that can provide services to many users in various area. However, the most difficult task to connect TDMA which uses synchronous method to ATM which used asynchronous transfer mode is the deterioration n of ATM transmission quality such as cell delay variation. Therefore, it is necessary to develop delay variation compensation method which can confront to the ATM. Efficient ways to use satellite links under the conditions such that maximum efficiency of the delay variation is limited under the required value, and the burst characteristic of transmission cell does not increase are being researched for translation between in ATM and TDMA. This paper points out the problems when time stamp method, reviewd in ground network, is applied to the satellite links to compensate the delay variation .To solve the problem, discrete cell count method is introduced along with the calculation of transmission capacity and error rate.Also, from the observation of stab-ility of the system and verification of reliability even when singal error occurred in the cell transmission timing information, the proposed compensation method appeared to be excellent.