• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.301-304
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• 2018

현재 기술의 블렌딩 된 동영상을 재생하는 과정에서 사용하는 기법은 각각의 이미지들을 스티칭 후 동영상을 재생하므로 이전 프레임의 경계를 고려하지 않는다. 이러한 과정에서 움직임이 동일한 경계 부분을 정확하게 파악하여 연결하지 못하는 오류가 발생하여 자연스러운 영상 재생이 불가능하다. 이에 대한 해결책으로 각 영상의 frame 을 추출하여 경계의 가중치를 비교한 후 차이가 클 경우 새로운 경계를 생성하여 적용하는 과정을 고안했다. 상기의 과정을 통해 블렌딩 된 동영상의 초기 오류가 크게 감소하였다. 본 논문에서는 해당 기술에 대한 구체적인 방안을 제시하여 다양한 동영상을 효과적으로 개선하여 오류를 최소화한 동영상을 얻을 수 있도록 하였다.

• Journal of the Korea Computer Industry Society
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• v.7 no.4
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• pp.309-320
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• 2006

The imprecise real-time system provides flexibility in scheduling time-critical tasks. Most scheduling problems of satisfying both 0/1 constraint and timing constraints, while the total error is minimized, are NP-complete when the optional tasks have arbitrary processing times. Liu suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on uniprocessors for minimizing the total error. Song et al suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on multiprocessors for minimizing the total error. But, these algorithms are all off-line algorithms. In the online scheduling, NORA algorithm can find a schedule with the minimum total error for the imprecise online task system. In the NORA algorithm, the EDF strategy is adopted in the optional scheduling.<중략> The algorithm, proposed in this paper, can be applied to some applications efficiently such as radar tracking, image processing, missile control and so on.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.364-366
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• 2004

소프트웨어 개발 과정의 여러 산출물 간의 일관성 유지는 최종 소프트웨어의 품질을 결정하는 중요한 요소가 되며, 운영단계의 유지보수 효율성에도 큰 영향을 미친다. 특히 구현 등 개발 후반부 활동을 진행시 발견된 하나의 오류는 그 이전 단계의 다수의 산출물의 오류로 인한 파급 결과이므로, 발견된 오류의 원인(Cause)가 되는 이전 단계의 오류를 효과적으로 추적할 수 있는 체계가 요구된다. 본 논문에서는 한 산출물의 오류가 다른 어떤 산출물의 어떤 세부항목들의 어떤 오류로 인한 파급 결과인지를 정의한 역추적(Backtracking) 그래프를 제안하여, 개발자가 오류를 발견 시 관련 산출물과 항목을 신속히 파악할 수 있도록 한다. 이를 이용하여 산출물간의 일관성 유지 노력과 시간을 최소화하고 일관성 유지의 정확성을 높일 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.72-82
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• 2004

This paper proposes more robust error concealment techniques (ECTs) for MPEG-2 intra coded frame. MPEG-2 source coding algorithm is very sensitive to transmission errors due to the use of variable-length coding. The transmission errors are corrected by error correction scheme, however, they cannot be revised properly. Error concealment (EC) is used to conceal the errors which are not corrected by error correction and to provide minimum visual distortion at the decoder. If errors are generated in intra coded frame, that is the starting frame of GOP, they are propagated to other inter coded frames due to the nature of motion compensated prediction coding. Such propagation of error may cause severe visual distortion. The proposed algorithm in this paper utilizes the spatio-temporal information of neighboring inter coded frames to conceal the successive slices errors occurred in I-frame. The proposed method also overcomes the problems that previous ECTs reside. The proposed algorithm generates consistent performance even in network where the violent transmission errors frequently occur. Algorithm is performed in MPEG-2 video codec and we can confirm that the proposed algorithm provides less visible distortion and higher PSNR than other approaches through simulations.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.15-20
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• 2021

The imprecise real-time scheduling can be used for minimizing the bad effects of timing faults by leaving less important tasks unfinished if necessary when a transient overload occured. In the imprecise scheduling, every time-critical task can be logically decomposed into two tasks : a mandatory task and an optional task. Recently, some studies in this field showed good schedulability performance and minimum total error by deferring the optional tasks. But the schedulability performance of the studies can be shown only when the execution time of each optional task was less than or equal to the execution time of its corresponding mandatory task. Therefore, in this paper, a new deferring strategy is proposed under the reverse execution time restriction to the previous studies. Nevertheless, the strategy produces comparable or superior schedulability performance to the previous studies and can minimize the total error also.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2390-2395
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• 2011

For intersymbol interference (ISI) compensation from communication channels with multi-path fading and impulsive noise, a decision feedback equalizer algorithm that minimizes Euclidean distance of error probability is proposed. The Euclidean distance of error probability is defined as the quadratic distance between the probability error signal and Dirac-delta function. By minimizing the distance with respect to equalizer weight based on decision feedback structures, the proposed decision feedback algorithm has shown to have significant effect of residual ISI cancellation on severe multipath channels as well as robustness against impulsive noise.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1032-1041
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• 1999

This paper proposes on-line scheduling algorithms that reduce the largest weighted error incurred by preemptive imprecise tasks running on a single processor system. The first one is a two-level algorithm. The top-level scheduling, which is executed whenever a new task arrives, determines the processing times to be allotted to tasks in such a way to minimize maximum weighted error as well as to minimize total error. The lower-level algorithm actually allocates the processor to the tasks. The second algorithm extends the on-line algorithm studied by Shih and Liu[4] by formalizing the top-level algorithm mathematically. The numerical simulation shows that the proposed algorithm outperforms the previous works in the sense that it greatly reduces the largest weighted error.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.10
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• pp.493-501
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• 2007

The imprecise real-time system provides flexibility in scheduling time-critical tasks. Most scheduling problems of satisfying both 0/1 constraint and timing constraints, while the total error is minimized, are NP-complete when the optional tasks have arbitrary processing times. Liu suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on uniprocessors for minimizing the total error. Song et at suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on multiprocessors for minimizing the total error. But, these algorithms are all off-line algorithms. In the online scheduling, the NORA algorithm can find a schedule with the minimum total error for the imprecise online task system. In NORA algorithm, EDF strategy is adopted in the optional scheduling. On the other hand, for the task system with 0/1 constraint, EDF_Scheduling may not be optimal in the sense that the total error is minimized. Furthermore, when the optional tasks are scheduled in the ascending order of their required processing times, NORA algorithm which EDF strategy is adopted may not produce minimum total error. Therefore, in this paper, an online algorithm is proposed to minimize total error for the imprecise task system with 0/1 constraint. Then, to compare the performance between the proposed algorithm and NORA algorithm, a series of experiments are performed. As a conseqence of the performance comparison between two algorithms, it has been concluded that the proposed algorithm can produce similar total error to NORA algorithm when the optional tasks are scheduled in the random order of their required processing times but, the proposed algorithm can produce less total error than NORA algorithm especially when the optional tasks are scheduled in the ascending order of their required processing times.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.307-308
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• 2008

본 논문에서는 장거리 양자암호 전송에 있어서 광섬유 전송 거리에 따른 오류율을 측정한 연구 결과를 소개한다. 특히 외부 환경에 안정된 양방향 양자 암호 전송 기술의 하나인 plug-and-play 방식의 구도에서 전송 거리를 극대화하는 노력에 있어서 가장 문제시되는 Raleigh-backscattering의 효과에 의한 양자비트 전송에서의 오류를 측정하였다. 아울러 이러한 오류를 최소화하면서 70 km 단일모드 광섬유 전송을 구현한 양자통신 결과를 소개하고자 한다.

• Journal of IKEEE
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• v.23 no.2
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• pp.479-486
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• 2019

CCN utilizes MHT-based content authentication scheme. Some schemes propose improved MHT scheme to solve the inefficiency of the MHT-based content authentication scheme which is caused by repetitive hash value computation and witness transmission. For using MHT, it is essentially needed to minimize the possibility of error-occurrence as well as to improve the efficiency of the authentication scheme. This paper describes the improved MHT scheme is error-prone. Also, it analyzes the effect of a segment authentication error, especially, the degree of error propagation.