• 한국멀티미디어학회논문지
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• 제14권8호
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• pp.1000-1009
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• 2011

영상 보간법은 영상의 크기변환에서 할당되지 못한 화소에 대한 값을 추정하는 기술로써, 보간된 결과 영상에서 나타나는 화질 열화 현상을 최소화하면서도 낮은 계산복잡도를 가지는 것이 필요하다. 본 논문에서는 반복적 오차 제거를 이용한 영상 보간법을 제안한다. 제안하는 방법은 5단계로 구성되며, 각각 손실 정보 계산 단계, 손실 정보 추정 단계 손실 정보 적용 단계 오차 계산 단계 오차 적용 단계이다. 실험을 통해서 기존의 방법보다 평균 3.3dB이상 PSNR(peak signal to noise rate)이 향상된 것을 알 수 있었고, 주관적인 화질도 개선된 것을 확인하였으며 계산복잡도가 최소 83% 이상 감소한 것을 측정하였다. 제안한 영상 보간 방법은 영상 복원 및 확대를 위한 다양한 응용 환경에서 유용하게 사용될 수 있다.

• 한국정보통신학회논문지
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• 제26권1호
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• pp.170-175
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• 2022

고성능 컴퓨팅 분야에서 오류의 영향을 완화하기 위해 사후 장애 관리 기법이 필요하다. 일반적인 오류 복구 기법은 체크포인트 기법이다. 이 기법은 체크포인트를 설정해서 주기적으로 응용 프로그램의 상태를 저장했다가, 오류가 발생했을 때 오류 발생 이전 상태로 시스템을 복구하는 것이다. 본 논문에서는 오류 발생 시간이 독립이고 동일한 일반적인 분포를 따른다는 가정에서 즉각적으로 오류를 감지하는 경우의 체크포인팅 모형을 분석한다. 두 체크포인트 사이에 많아야 하나의 오류만 발생한다는 가정을 제거한다. 체크포인트 발생 시간, 고장 시간, 복구 시간 등이 주어질 때, 시스템의 신뢰도를 유도한다. 또한, 오류 발생 시간이 지수 분포를 따르는 경우에 최적의 체크 포인팅 시간 간격을 구한다.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.138-145
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• 1997

This paper proposes an adaptive algorithm for the quantization step size control of MPEG-2, using the information obtained from the previously encoded picture. Before quantizing the DCT coefficients, the properties of reconstruction error of each macro block (MB) is predicted from the previous frame. For the prediction of the error of current MB, a block with the size of MB in the previous frame are chosen by use of the motion vector. Since the original and reconstructed images of the previous frame are available in the encoder, we can calculate the reconstruction error of this block. This error is considered as the expected error of the current MB if it is quantized with the same step size and bit rate. Comparing the error of the MB with the average of overall MBs, if it is larger than the average, small step size is given for this MB, and vice versa. As a result, the error distribution of the MB is more concentrated to the average, giving low variance and improved image quality. Especially for the low bit application, the proposed algorithm gives much smaller error variance and higher PSNR compared to TM5 (test model 5).

• 한국안전학회지
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• 제18권2호
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• pp.104-118
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• 2003

It has been criticized that conventional human reliability analysis (HRA) methodologies for probabilistic safety assessment (PSA) have been focused on the quantification of human error probability (HEP) without detailed analysis of human cognitive processes such as situation assessment or decision-making which are crticial to successful response to emergency situations. This paper introduces a new human reliability analysis (HRA) methodology, AGAPE-ET (A guidance And Procedure for Human Error Analysis for Emergency Tasks), focused on the qualitative error analysis of emergency tasks from the viewpoint of the performance of human cognitive function. The AGAPE-ET method is based on the simplified cognitive model and a taxonomy of influencing factors. By each cognitive function, error causes or error-likely situations have been identified considering the characteristics of the performance of each cognitive function and influencing mechanism of PIFs on the cognitive function. Then, overall human error analysis process is designed considering the cognitive demand of the required task. The application to an emergency task shows that the proposed method is useful to identify task vulnerabilities associated with the performance of emergency tasks.

• 한국초전도ㆍ저온공학회논문지
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• 제18권3호
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• pp.21-24
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• 2016

Recently, production technique and property of the High-Temperature Superconductor (HTS) tape have been improved. Thus, the study on applying an HTS magnet to the high magnetic field application is rapidly increased. A Nuclear Magnetic Resonance (NMR) spectrometer requires high magnitude and homogeneous of central magnetic field. However, the HTS magnet has fabrication errors because shape of HTS is tape and HTS magnet is manufactured by winding HTS tape to the bobbin. The fabrication errors are winding error, bobbin diameter error, spacer thickness error and so on. The winding error occurs when HTS tape is departed from the arranged position on the bobbin. The bobbin diameter and spacer thickness error occur since the diameter of bobbin and spacer are inaccurate. These errors lead magnitude and homogeneity of central magnetic field to be different from its ideal design. The purpose of this paper is to investigate the effect of winding error, bobbin diameter error and spacer thickness error on the central field and field homogeneity of HTS magnet using the virtual NMR signals in MATLAB simulation.

• 정보처리학회논문지C
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• 제9C권3호
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• pp.375-384
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• 2002

현재의 인터넷은 가변적인 대역폭과 패킷손실 그리고 지연으로 인하여 대화식 응용의 QoS 보장이 어렵다. 특히 최근에 정보의 기반구조로 중요성이 강조되고 있는 VOIP는 패킷손실률과 종점간지연이 클 때 통화품질이 크게 떨어지므로 네트웍 수준에서나 응용 수준에서 에러제어 기법이 요구된다. 인터넷 전화와 같은 대화식 응용을 위한 응용 수준의 에러 제어 기법으로 FEC(Forward Error Correction)가 가장 많이 사용되고 있는데, 이 기법은 주정보와 더불어 부가정보를 전송함으로서 패킷손실을 복구하는 방법으로 네트웍의 상태에 따라 적응적으로 부가정보의 양을 조절한다. 그러나 기존의 알고리즘들은 패킷손실률만을 고려하여 부가정보를 조절하였으며 부가 정보를 증가시킬 때 수반되는 종점간지연을 간과함으로써 통화품질을 떨어뜨리는 단점이 있다. 본 논문에서는 패킷손실률뿐만 아니라 종점간지연을 고려하는 FEC기반 에러제어 기법인 SCCRP (Selecting a Codec Combination using Reward and Penalty)를 제안한다. 실험 결과, SCCRP는 다른 알고리즘들에 비해 복구 후 패킷손실률은 물론 복구 후 종점간지연을 낮게 유지하였다.

• 한국전기전자재료학회논문지
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• 제24권12호
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• pp.949-954
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• 2011

In this study, the characteristics and error ranges of the mechanical bonding strength were analyzed according to before and after thermal shock test for various chips of automotive application component using Sn-3.0Ag-0.5Cu solder. In the after thermal shock test, the mechanical bonding strengths tend to decrease, meanwhile decreasing rates of mechanical strengths were less then 12% at specimen's bonding area below 3.5$mm^2$, and were from 17 to 21% at specimen's bonding area above 12 $mm^2$. On the other hand, Specimen's mean deviation rates were about 5% at specimen's bonding area more than 12 $mm^2$. Inversely, at specimen's bonding area is less then 3.5 $mm^2$, mean deviation rates were increased to about 8%. It means that the smaller device size is, the larger mean deviation rate. In addition, error ranges and deviation rates of the mechanical bonding strengths may differ slightly depending on their bonding area. Furthermore, process conditions as well as method of mechanical reliability evaluation should be established to reduce the error ranges of bonding strength.

• 대한인간공학회지
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• 제31권1호
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• pp.261-269
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• 2012

Objective: The aim of this study is to develop an analysis method to extract plausible types of errors when using a smart mobile in nuclear power plants. Background: Smart mobiles such as a smart-phone and a tablet computer(smart-pad) are to be introduced to the various industries. Nuclear power plant like APR1400 already adopted many up-to-date digital devices within its main control room. With this trend, various types of smart mobiles will be inevitably introduced to the nuclear field in the near future. However nuclear power plants(NPPs) should be managed considering a big risk as a result of the trend not only economically but also socially compared to the other industrial systems. It is formally required to make sure to reasonably prevent the all hazards due to the introduction of new technologies and devices before the application to the specific tasks in nuclear power plants. Method: We define interaction segments(IS) as a main architect of interaction description, and enumerate all plausible error segments(ES) for a part of design evaluation of digital devices. Results: We identify various types of interaction errors which are coped with reasonably by interaction design using smart mobiles. Conclusion: According to the application result of the proposed method, we conclude that the proposed method can be utilized to specify the requirements to the human error hazards in digital devices, and to conduct a human factors review during the design of digital devices. Application: The proposed method can be applied to predict the human errors of the tasks related to the digital devices; therefore we can ensure the safety to apply the digital devices to be introduced to NPPs.

• 비파괴검사학회지
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• 제4권1호
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• pp.11-22
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• 1984

In the straight beam inspection of ultrasonic wave, the method for evaluating flaw size by AVG diagram is useful as a method for the quantitative evaluation of results of ultrasonic flaw detection. This study was carried out the measure the size of circular flat flaw with the inclination by straight beam inspection and could be decreased the error of application due to the inclination of flaw by AVG diagram in consideration of correction coefficient. From the result of the experiment, the error by means of the application of experimental values to AVG diagram was increased as the inclination angle grows. Also, it n s increased the error of application as the detecting frequency and diameter of flaw grows in the same inclination angle. In case of diameter of flaw 6mm, AVG diagram could be applied to the inclination angle $3^{\circ}$ for 5 MHz, $7^{\circ}$ for 2.25 MHz, $15^{\circ}C$ for 1 MHz in the range of 20% error and the theory was concided with the experiment to $5^{\circ}C$ for 5 MHz, $10^{\circ}C$ for 2.25 MHz, $15^{\circ}C$ for 1 MHz in the range of 10% error by correction eq. (45) due to the inclination angle. Therefore, it is considered that the results obtained from this study will be somewhat helpful informations for the size evaluation of circular flat flaw with the inclination.

• 디지털콘텐츠학회 논문지
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• 제4권2호
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• pp.139-146
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• 2003

본 논문은 ERA(Error Recovery Agent)의 설계와 구축을 설명한다. ERA는 멀티미디어 원격 교육 시스템에서 소프트웨어 오류를 감지, 공유, 복구하기에 적합한 시스템이다. 이 시스템은 ED, ES, ER로 구성되어 있다. ED는 훅킹 기법으로 오류를 감지한다. ES는 멀티미디어 원격 교육 시스템에서 오류를 공유하는 에이전트이다. ER은 오류를 복구하는 에이전트이다. 본 논문에서는 멀티미디어 공동 작업 환경에서 하나의 오류 응용을 미디어로 취급하고 복구하는 방법을 제안한다.