• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.9-11
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• 1999

멀티미디어 DBMS는 연속매체를 서비스할 때 동시에 보다 많은 사용자들에게 일정한 서비스 품질을 유지하면서 서비스를 제공할 수 있어야 한다. 이를 위하여 멀티미디어 DBMS를 위한 저장시스템은 보다 큰 디스크 대역폭을 지원해야 하므로 디스크 배열의 구조를 갖는 것이 바람직하다. 디스크 배열 환경에서 다수의 연속매체를 병행적으로 서비스할 때 요구 데이터를 순차접근에 의하여 검색할 수 있으면 디스크 대역폭을 탐색시간 등으로 소모하지 않으므로 고속 디스크 대역폭을 유지할 수 있다. 또한, 디스크 접근시 디스브 부하 균형을 유지할 수 있으면 자원 활용율이 높은 고성능의 저장 시스템이 될 수 있다. 본 논문에서는 연속매체들을 순차접근에 의해서 처리하면서 디스크 부하 균형을 유지할 수 있는 데이터 배치 기법을 제안한다. 제안한 데이터 배치기법에 의한 성능평가는 모의 실험 전용틀인 AweSim 2.0을 사용하였다.

• The KIPS Transactions:PartA
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• v.11A no.7 s.91
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• pp.547-554
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• 2004

To play back CM (Continuous Media) in online mode, the multimedia system Is required to have a real-time disk scheduling scheme that can efficiently fulfill the strict temporal constraints of serviced CM streams to prevent hiccups. In general, such disk scheduling is performed based on the concept of periodic prefetching since a CM stream has a rather long Playback time. In this paper, we also propose a periodic prefetching scheme that runs by using real-time disk channels, called on-time delivery channels. Since the channels are generated from the bulk-SCAN algorithm and they can be allocated in a very flexible manner based on the EDF (earliest-deadline-first) algorithm, the proposed scheme provides a better Performance in terms of I/O throughput and the average response time, as well as hiccup-free playback of concurrent CM streams. To show that the proposed scheme outperforms other methods, we give some simulation results.

• Journal of the Korea Computer Industry Society
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• v.4 no.10
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• pp.695-702
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• 2003

It is necessary for us to have proper synchronization technology in order for continuous media and non-continuous media to be integrated and presented. In case of continuous media, it would be possible to convey significant information only after relevant synchronization is completed in the continuous media itself. In this thesis, I mentioned integration of these multi-media, basic notion of synchronization and synchronization technology. In order to process synchronization, I have researched into information used to fractionize methods regarding synchronization. And I have also discussed synchronization problems found in integration of continuous multi-media and through researching into case study of MHEG, I have analyzed how the synchronization of multi-media is processed and applied.

• The Transactions of the Korea Information Processing Society
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• v.4 no.5
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• pp.1172-1181
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• 1997

A militimedia data is a data mixed of formatted data like an audio and video. Multimedia data has characteristics that it need large amount of storage,wide network bandwith andreal time responsibolity. Because of these characteristocs, the VOD server and continous media storage server have a disk stripe structure or disk stripe sructure or disk array structure(RAID).In the parallel disk access system,high-speed play-back of continous media using segment interleavung may not ensure Qos pf other cioents because of the concentrated load within some disks. The load concentration of disks is related to both the number of disks in the system and playback rate of contimous media.In this paper. we describe that high-speed playback scheme,which is independent of the number of disk and plyback rate can be achieved by technique of changing the in-teval of access to segnent location.We show the experimental result of this technique in this pater.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.8
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• pp.905-917
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• 1999

멀티미디어 시스템에서 수행되는 부하 중 상당 부분은 정해진 시간에 주기적으로 수행되어 연속 매체(continuous media)를 처리하는 주기 태스크들이다. 연속 매체들을 처리하는 두 주기 태스크의 수행 요청 시간(release time)간에 인공적인 위상(phase)을 줄 경우, 전체 부하의 처리 타이밍에 영향을 주게 되며, 특히, 적절한 위상을 부여할 경우 부하가 고르게 분산된다. 부하의 고른 분산은 태스크 간섭을 줄여 지터(jitter), 종료시한 초과(deadline miss), 그리고 긴 응답 시간(response time) 등의 문제를 해소시킨다. 본 논문에서는 새로운 위상 스케줄링(phased scheduling) 알고리즘 및 알고리즘을 개발하고 평가할 수 있는 실험 환경을 제안한다. 본 논문에 제시된 알고리즘은 저자들의 선행 논문 1 에서 제시한 알고리즘의 대안이다. 새로운 알고리즘은 정확하게 최적의 위상을 찾지는 않으나 기존 알고리즘보다 빠르게 수행되며 적용 범위가 넓다.Abstract A multimedia system consists of substantial amount of continuous media workload scheduled periodically at deterministic time points. Artificial phase between the invocation times of any two continuous media tasks affects the timing of the entire workload. A proper phase configuration distributes workload uniformly over time and reduces task interference that may otherwise result in jitter, deadline miss, and long response time. The objective of this paper is to work out a phased scheduling algorithm and to evaluate its effectiveness. The algorithm in this paper is an alternative approach to our previous work 1 . It is almost as accurate as the predecessor but two of three times faster in identifying the appropriate phase vector.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.355-364
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• 2005

With fast advances in computing power and network technologies, online streaming services of continuous media (CM) have been popularly implemented on the Web. To implement such services, a variety of CM streams need to be processed efficiently, so that the Sweep scheme was proposed. This scheme has several advantages such as hiccup-free playbacks and seek-time optimization. In this scheme, however, the entire CM streams are scheduled with a single scheduling period, called a cycle. Since only one scheduling period is allowed in this scheme, a significant amount of disk time is usually wasted because of its inflexible disk schedules. To solve this, we propose a new dynamic Sweep scheme. For this, we devise an algorithm that is able to expand scheduling periods of serviced CM streams and propose a new admission control mechanism guaranteeing hiccup-free playbacks. To show performance gains, we execute various simulation experiments. From the experimental results, we can see that the proposed scheme outperforms the Sweep scheme in terms of disk utilization and scheduling flexibility.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3175-3184
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• 1997

To support large storage capacity and real-time characteristics of continuous media storage systems, we need to improve the performance of disk I/O subsystems. To improve the performance, we exploited buffer sharing scheme that reduces the number of disk I/Os. We utilized the advance knowledge of continuous media streams that is used to anticipate data demands, and so Promoting the sharing of blocks in buffers. In this paper, we proposed a buffer replacement algorithm that enables subsequent users requesting the same data to share buffer efficiently. The proposed algorithm manages buffers by utilizing reference interval information of blocks. In order to verify validity of the proposed algorithm, we accomplished simulation experiments and showed the results of performance improvements compared to traditional buffer replacement algorithms.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.238-241
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• 2012

모든 기록매체의 장기보존성과 신뢰성은 보존에 있어 중요한 요소 중 하나이다. DVD 광기록매체 또한 신뢰성을 평가하기 위한 다양한 국제표준 및 연구가 진행되었다. 국가기록원은 각급 기관에서 생산되어 이관된 다양한 종류의 DVD 광매체를 보존하고 있으며, 이에 대한 상태평가를 위해 선행된 표준 및 연구 내용을 바탕으로 이관된 광매체에 대한 상태를 측정을 하였다. 본 연구에서는 이관된 DVD 매체에 대한 평가 기준을 8개의 연속된 ECC블럭의 PI 에러값을 사용하였다. 측정된 PI 에러 값은 생산년도, 제조회사, 에러 발생 위치로 분류하였으며 시간에 따른 열화 정도, 기록 품질 그리고 에러 발생 위치에 따른 매체 상태와의 연관성을 연구하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.4
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• pp.84-92
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• 2009

In this paper, using the received signal strength of radio beacon such as Wi-Fi, Bluetooth, CDMA and GPS signal from the satellite, we propose the system of positioning which considered indoor and outdoor based on the Place Lab. Conventional Place Lab utilize the various positioning parameters to estimate the indoor location. However, this conventional system has limitations with respect to the range and efficiency of usage. Therefore, we defined the converged model of multisensor data and re-organized the Place Lab to overcome the limitation of a conventional system. Proposed system uses the radio beacon signal and GPS signal together to estimate the location. Furthermore, it provides the seamless PNS service with many mobile devices because this system realized by the OSGi bundle. This proposed system has evaluated the performance with SAMSUNG T*OMNIA SCH-M490 smart phone and the result shows the system is able to support the PNS service.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.196-198
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• 2002

이동 기술의 발전으로 위치와 이동 패턴이 연속적으로 변화하는 객체가 증가하였다. 시간에 따라 객체가 이동하면서 그 위치와 모양이 연속적으로 변화하는 것을 이동 객체라 한다. 과거의 DBMS는 연속적으로 이동 정보가 변화한다. 이러한 정보를 저장하는 매체인 이동 객체 데이터베이스의 갱신 횟수는 매우 중요하다. 본 논문에서 객체는 일반적으로 일정한 패턴으로 이동한다고 가정한다. 이러한 객체의 일정한 이동 패턴을 이용하여, 이동 객체 데이터베이스의 갱신 횟수를 최소화하면서, 효과적으로 인덱싱 하는 전략을 제시한다. 또한 질의에 대한 객체 위치의 오차를 최소화하여 반환해 주는 질의 처리 기법을 제안한다.