• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5885-5894
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• 2011

Ubiquitous environment is expected to be result of researches and studies in ubiquitous home base on. However, because of the complexity of the ubiquitous home base on, the realization of error handling seems impossible. In this paper, we present how to detect and recover from these errors for the Ubiquitous Home utilizing a fault simulator developed for the study and through a variety of experiments, results were discussed and analyzed. Base on the said results, future works are also discussed.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.87-92
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• 2010

The design of avionic embedded systems requires high-dependability. In this paper, we studied the dependability of the triple modular redundancy (TMR) hardware for highly reliable aviation embedded system. In order to evaluate the dependability of the base ARM processor and the TMR ARM processor, we developed the simulation model of the reduced ARM and TMR ARM processors and performed the simulation fault injection for the analysis of the dependability of the two targets. In the fault injection experiments, we calculated the error recovery rate of the two the processor models. From the experimental results, we could confirm that the reliability of the TMR ARM processor was greater than the single ARM processor by ten times in some cases.

• The KIPS Transactions:PartD
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• v.14D no.7
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• pp.801-808
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• 2007

Video coding standards such as MPEG-2, MPEG-4, H.263, and H.264 transmit a compressed video data using wired/wireless communication line with limited bandwidth. Because highly compressed bit-streams is likely to fragile to error from channel noise, video is damaged by error. There have been many research works on error concealment techniques, which recover transmission errors at decoder side [1, 2]. We designed an error concealment technique for lost motion vectors of H.264 video coding. In this paper, we propose a Kalman filter based motion vector recovery scheme, and experimented with standard video sequences. The experimental results show that our scheme restores original motion vector with more precision of 0.91 - 1.12 on average over conventional H.264 decoding with no error recovery.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.241-248
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• 2006

Mobile computing has such characteristics as portability, wireless network, mobility, etc. These characteristics cause various problems to mobile terminals like frequent disconnection, high error rate, and varying network status. These problems motivate us to develop an adaptive error control mechanism for supporting multimedia service in mobile computing environment. In this paper, we propose the Adaptive Error Control(AEC) scheme using client's buffer size and current error rate. After categorizing the status into four groups according to client's buffer size and current error rate, this scheme applies an appropriate error control scheme to each status. In this scheme, thresholds of buffer size and error rate are determined by the data transmission time, play rate and average VOP size, and by the probability of error for a sequence of packets. The performance of proposed scheme is evaluated by flaying MPEG-4 files on an experimental client/server environment, respectively. The results show that error correcting rate is similar to other schemes while the time for correcting error reduce a little. In addition, the size of data for correcting error is decreased by 23% compared with FEC and Hybrid FEC, respectively. Theses results demonstrate that the proposed scheme is more suitable in mobile computing environment with small bandwidth and varying environment than existing schemes.

• Journal of the Korea Convergence Society
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• v.7 no.4
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• pp.25-32
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• 2016

When using reliable multicast protocol over air links, the multicast packets lost in the air link cause the initiation of retransmission request packets and the implosion of retransmission packets, which deteriorate multicast session performance. This paper proposes on the efficient reliable multicast mechanism in wireless networks utilizing the Agents. In this paper we show the design of a retransmission agent which improves the performance of reliable multicast sessions in wireless network. The main idea is to cache reliable multicast packets at the base station and perform local retransmissions across the wireless link. MATLAB has been used to simulate and to get performance results for signaling overhead and processing delay through the comparison of the proposed agent model to the Multicast File Transfer Protocol. It has been proven from the simulation results that the proxy module make pass trials shorter in Multicast File Transfer Protocol.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1335-1337
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• 2007

홈 네트워크는 네트워킹 기술, 기반 소프트웨어의 발전에 따라 급속히 확산되어 가고 있다 본 논문에서는 홈네트워크 상에서 응용 S/W 의 결함을 미리 감지하여 알려줄 수 있는 시스템으로 하드웨어 장애가 아닌 소프트웨어의 오류를 감지하여 복구할 수 있는 시스템을 제안한다. 본 논문에서 제안하는 시스템은 두레(DOORAE: Distance Object Oriented collaboRAtion Environment)라는 원격 화상 교육 시스템을 기반으로 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.15-17
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• 2000

실시간 시스템에서 예상치 못한 오류 발생은 성능에 악영향을 미친다. 이를 예방하기 위하여 체크포인팅이라는 후방 에러복구기법을 이용하여 오류 발생시에도 예측 가능한 결과를 보장할 수 있다. 실시간 시스템에서의 체크포인팅은 비실시간 시스템과는 달리 시간제약성을 만족시켜야 하기 때문에 비실시간에는 최적인 체크포인팅 간겨곽는 다르게 고려 되어야 한다. 이런 체크포인트 간격에 따른 성능의 차이를 시뮬레이션을 통하여 확인하였고 결과를 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7A
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• pp.1220-1226
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• 2001

실시간 시스템에서 예상치 못한 오류 방생은 성능에 악영향을 미친다. 이를 예방하기 위하여 체크포인팅(checkpointing)이라는 후방 에러복구기법을 이용하여 오류 발생시에도 예측 가능한 결과를 보장할 수 있다. 실시간 시스템에서의 체크포인팅은 비실시간 시스템과는 달리 시간제약성을 만족시켜야 하기 때문에 비실시간에서 최적인 체크포인팅 간격과는 다르게 고려되어야 한다. 본 논문에서는 체크포인트 간격에 따른 실시간 시스템과 비실시간 시스템간의 성능의 차이를 시뮬레이션을 통하여 확인하였고 결과를 분석하였다.

• Journal of Digital Contents Society
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• v.3 no.2
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• pp.235-243
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• 2002

This paper explains the design and implementation of the ESA(Error Sharing Agent). ESA is a system that is suitable for detecting, sharing and recovering software error based on multimedia CSCW(Computer Supportes Cooperated Work). This system consists of an ED, ES, and ER. ED detects an error by hooking techniques. ES is an agent which is an error sharing system for distributed multimedia collaboration environment With error sharing system, a group cooperating users can share error applications. From the perspective of multimedia collaborative environment, an error application becomes another interactive presentation error is shared with participants engaged in a cooperative work. We propose how an error application can be treated as 'media' in a multimedia collaborative environment.

• Journal of Digital Contents Society
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• v.15 no.1
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• pp.87-91
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• 2014

This paper suggested a web based error manager for societal security service. This is a system that is suitable for detecting, sharing and recovering software error based on multimedia CSCW(Computer Supportes Cooperated Work). With error sharing system, a group cooperating users can share error applications. Our a web based error manager for societal security service enables user to share error objects through interaction awareness. This method has a file sharing, a window copy, a window overlay, or a window sharing. We implemented the web based error manager for societal security service so that the users participated in collaborative work may refer shared error objects as the same view to others.