• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.131-134
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• 2009

The MOST network, which is a network for vehicle infotainment network, requires efficient channel allocation to provide multimedia service effectively. Though there is a study on channel allocation according to network traffic as studies on channel allocation for MOST network, there have scarcely been studies on channel allocation according to bandwidth of multimedia for transferring. Therefore, in this paper, we propose the channel allocation method which calculates the number of channels by analyzing multimedia data for transferring and assigns the optimal number of channels for the given data. The proposed method reduces wasting of channels by optimally allocating channels and prevents initializing network due to change of Boundary Descriptor.

• Annual Conference of KIPS
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• 2023.05a
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• pp.413-414
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• 2023

IT 기술의 발달로 E-Commerce 분야는 실시간으로 발생되는 데이터양이 증가하고 있으며, 발생된 데이터는 개인화 맞춤 서비스에 많이 활용되고 있다. 그러나 신생 E-commerce 기업은 신규 상품 및 기존 상품에 대한 정보와 고객 간의 상호 작용 데이터가 존재하지 않아 콜드 스타트 문제가 발생한다. 이에 본 논문에서는 E-commerce 환경에서 실시간 사용자 구매패턴 분석을 통한 사용자 상품 추천 시스템을 제안한다. 제안하는 시스템은 Kafka와 Spark를 사용해 실시간 스트림을 데이터를 처리한다. 주요 기능은 ALS 알고리즘과, FP-Growth 알고리즘을 적용해 콜트 스타트 문제를 해결하며, 사용자 구매 패턴 분석을 통한 분석 결과에 맞는 상품을 사용자에게 추천한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.602-611
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• 2002

Recent advances in technology have resulted in rapid growth in mobile communication. With this explosive growth, reliable transmission and error resilient technique become increasingly necessary to offer high quality multimedia service. The success of error resilient techniques at decoder sensitively depends on error detection performance. Therefore, this paper proposes a computationally very simple and efficient error detection technique using fragile watermark for real-time video communication. To balance between image quality degradation and error detection efficiency, fragile watermark is embedded only in least significant bits of selected transform coefficients. The proposed method is workable without additional bit in video bitstream and can be implemented very efficiently. This method will be useful in video communication in error prone environment such as wireless channel.

• 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 KIISE:Computer Systems and Theory
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• v.29 no.6
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• pp.318-330
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• 2002

This paper discusses the design and implementation of a video server which uses tertiary device, such as magneto-optical jukebox or tape library, as a source of media archiving. In order to handle the tertiary device in the framework of disk-based stream service model, a sophisticated streaming model is required for server and it should consider the device-specific performance characteristics of tertiary storage. We have carefully designed the streaming mechanism for server whose key functionalities include stream scheduling, disk caching and admission control. The proposed system has been implemented on Windows 2000 platform which is equipped with a magneto-optical jukebox. The design principles of the server are validated with the experiments and the performance characteristics is analyzed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.2
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• pp.71-75
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• 2013

Recently proliferating heterogeneous multimedia service environments should be able to deal with many different transmission speeds, image sizes, or qualities of video. However, not many existing video compression standards satisfy those necessities. To satisfy the functional requirements, the standardization of the H.264/AVC Scalable Extension (SE) technique has been recently completed. It is an extension of the H.264/AVC which can encode several image sizes and qualities at the same time as a single bitstream. To perform optimum mode decision, motion estimation is performed for all MB modes, and the RD costs are compared to identify an MB mode with the smallest RD cost. This increases computational complexity of H.264/AVC SE encoding. In this paper, we propose an early skip mode detection scheme to reduce candidate modes and suggest an algorithm of fast mode decision utilizing reference modes according to the mode history.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.291-294
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• 2009

최근 멀티미디어 기능을 가지는 다양한 기기가 보급되고, 이러한 기기들을 위해 다양한 화질과 해상도를 가지는 멀티미디어 서비스가 소비되고 있다. 이러한 서비스들은 목적 및 기기의 종류에 따라 전송환경이 다르기 때문에, 압축된 영상이 가지는 특성 또한 다르다. 일반적인 동영상 압축 표준에서 구문요소들에 코드워드를 할당하는 방법은 표준화 과정에서 얻어진 확률과 통계적인 수치에 의해 최적으로 결정된 것이다. 하지만 확률과 통계적인 수치는 영상의 특성에 따라 차이가 있기 때문에 최적의 코드워드는 항상 달라지는데, 현재 표준압축방법은 이러한 확률적인 특성이나 통계적인 수치를 반영하기 어려운 단점을 가진다. 이에 본 논문에서는 영상의 특징 및 부호화 조건에 따른 압축데이터의 특징을 반영하여 슬라이스 단위로 마크로 블록 타입에 대한 코드워드를 적응적으로 할당하는 방법을 제안한다. 제안하는 방법에서 부호화 조건에 따른 압축 데이터의 특징을 파악하기 위해 정해진 부호화 조건에 따라 한 번의 부호화를 수행하여 마크로 블록 타입에 대한 슬라이스 통계를 구한다. 그 다음 구해진 통계에 근거하여 마크로블록 타입에 대해 최적의 코드워드를 할당하고, 이 코드워드에 근거하여 다시 한 번 부호화를 수행하고 이렇게 발생된 비트스트림을 복호화기로 전송하게 된다. 본 논문에서 제안한 방법을 적용한 실험결과 BD-rate가 약 0.2~1.7% 정도 감소하는 결과를 얻을 수 있었다.

• 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 Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11A
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• pp.1253-1262
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• 2004

The Data Over Cable System Interface Specification (DOCSIS) protocol enables the delivery of Internet Protocol(IP) traffic over Cable TV networks with significantly higher data rates. In this paper, we assessed the performance of the DOCSIS protocol using the OPNET. The simulation can be used to predict the upstream system throughput, mean access delay and channel utilization on varying packet size and transmission stream and wid/without concatenation, and it has shown that maximum system throughput is 4.6 Mbps for channel capacity of 5.12 Mbps and packet size of 1500 bytes. The mean access delay varies depending on the offered load, and it is assumed that the offered load does not exceed the capacity of the channel. Excess offered load causes service starvation according to the assigned priority.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1111-1120
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• 2013

CAS used in IPTV or DTV has an environment of sending single type of contents through single streaming. But it can be improved to support users' various video applications through single streaming by combining with SVC. For such an environment, efficiency should be firstly considered, and hierarchical key management methods for billing policy by service levels should be applied. This study aims to look into considerations to apply SVC to CAS and propose SVC encryption in CAS environment. The security of the proposed scheme is based on the safety of CAS and oneway hash function. If the proposed scheme is applied, scalability can be efficiently provided even in the encrypted contents and it is possible to bill users according to picture quality. In addition, the test results show that SVC contents given by streaming service with the average less than 10%overhead can be safely protected against illegal uses.