• 전기학회논문지
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• 제59권8호
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• pp.1406-1415
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• 2010

As process technology for semiconductor goes beyond the ultra-deep submicrometer regime, interconnect reliability on a chip has become a serious design concern. As process parameters scale, interconnect widths are reduced rapidly while the current flowing through the interconnect does not decrease in a proportional manner. This trend increases current densities in metal interconnects which may lead to poor reliability for electromigration. Hence, it is critical to estimate the current amount passing through the interconnects earlier in semiconductor design stages. The purpose of this paper is to propose a fast yet accurate current estimation technique that can offer not only analysis time equivalent to those offered by the previous approximation methods but also a relatively precise estimation by using closed-form equations. The accuracy of the proposed technique was confirmed to be about 8 times better on average when compared to the previous work.

• 드라이브 ㆍ 컨트롤
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• 제14권3호
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• pp.40-49
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• 2017

This study presents an online estimation of an excavator's rotational inertia by using recursive least square with forgetting. It is difficult to measure rotational inertia in real systems. Against this background, online estimation of rotational inertia is essential for improving safety and automation of construction equipment such as excavators because changes in inertial parameter impact dynamic characteristics. Regarding an excavator, rotational inertia for swing motion may change significantly according to working posture and digging conditions. Hence, rotational inertia estimation by predicting swing motion is critical for enhancing working safety and automation. Swing velocity and damping coefficient were used for rotational inertia estimation in this study. Updating rules are proposed for enhancing convergence performance by using the damping coefficient and forgetting factors. The proposed estimation algorithm uses three forgetting factors to estimate time-varying rotational inertia, damping coefficient, and torque with different variation rates. Rotational inertia in a typical working scenario was considered for reasonable performance evaluation. Three simulations were conducted by considering several digging conditions. Presented estimation results reveal the proposed estimation scheme is effective for estimating varying rotational inertia of the excavator.

• 산업경영시스템학회지
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• 제17권32호
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• pp.17-26
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• 1994

This paper deals with the estimation of limiting distribution parameters, which have a close relation with product reliability characteristics in reliability test. Among the many kinds of estimation methods, probability paper is commonly used. The limiting probability paper is very convenient, but it has a great disadvantage in estimation accuracy by plotting method. It is very difficult to get the same results even if one use the same data several times. A computer program for the regression method is used for the parameter estimation to reduce these errors. Especially, the computer graphic program was written in GW-BASIC 3.22 language and a couple of running examples for user's reference appears in the appendix part.

• 산업경영시스템학회지
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• 제16권28호
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• pp.145-155
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• 1993

This paper studies the estimation of hazard parameters, which have a close relation with product reliability characteristics in reliability test. Among the many kinds of estimation methods, hazard Probability Paper(HPP) is commonly used. The HPP is very convenient, but it has a great disadvantage in estimation W by plotting method It is very difficult to get the same results even if one use the same data several times. A computer program for the regression method is used for the parameter estimation to reduce these errors. Especially, the computer graphic program was written in GW-BASIC 3.22 language and a couple of running examples for user's reference appears in the appendix part.

• Journal of Information Technology Applications and Management
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• 제25권4호
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• pp.115-122
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• 2018

Software reliability has the greatest impact on computer system reliability and software quality. For this software reliability analysis, In this study, we compare and analyze the trends of the properties affecting the reliability according to the shape parameters of Erlang distribution based on the finite fault NHPP. Software failure time data were used to analyze software failure phenomena, the maximum likelihood estimation method was used for parameter estimation. As a result, it can be seen that the intensity function is effective because it shows a tendency to decrease with time when the shape parameters a = 1 and a = 3. However, the pattern of the mean value function showed an underestimation pattern for the true values when the shape parameters a = 1 and a = 2, but it was found to be more efficient when a = 3 because the error width from the true value was small. Also, in the reliability evaluation of the future mission time, the stable and high trend was shown when the shape parameters a = 1 and a = 3, but on the contrary, when a = 2, the reliability decreased with the failure time. Through this study, the property of finite fault NHPP Erlang model according to the change of shape parameter without existing research case was newly analyzed, and new research information that software developers can use as basic guideline was presented.

• Computational Structural Engineering : An International Journal
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• 제1권2호
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• pp.81-87
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• 2001

A framework for reliability analysis of structural components and systems under conditions of statistical and model uncertainty is presented. The Bayesian parameter estimation method is used to derive the posterior distribution of model parameters reflecting epistemic uncertainties. Point, predictive and bound estimates of reliability accounting for parameter uncertainties are derived. The bounds estimates explicitly reflect the effect of epistemic uncertainties on the reliability measure. These developments are enhance-ments of second-moment uncertainty analysis methods developed by A. H-S. Ang and others three decades ago.

• 비파괴검사학회지
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• 제21권6호
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• pp.618-629
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• 2001

본 논문은 고압 커패시터의 고장분석과 신뢰성 예측 결과를 다루고 있다. 부품의 수명과 고장률을 예측하기 위해서 두 가지 방법으로 고장 모드와 고장 메커니즘을 연구하였다 에폭시 수지로 성형된 고압 커패시터가 절연내압 시험 하에서 저항이 제로로 되는 고장에 대하여, 근본원인 고장분석 체계를 효과적으로 수립함으로써 고장 메커니즘의 원인을 분석하였다. 특히 세라믹-에폭시 계면에서의 절연파괴 고장 현상이 강조되었으며, 본 연구에서 얻어진 결과의 타당성은 마그네트론에 장착된 고압 커패시터의 열사이클 시험 수행에 의한 가속시험 결과로부터 입증되었다. 시험 결과들은 결함이 있는 로트를 신속히 규명하고 $B_{10}$ 수명을 결정하는데 유용하게 사용할 수 있다. 또한, 유전체의 절연파괴에 대해서 부하-강도 간섭모델을 이용하여 고장률을 예측하였다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제9권4호
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• pp.89-100
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• 2020

최근 보험 처리과정에서 소용되는 시간과 비용을 절감하고자, 자동차 보험에 블록체인 스마트 컨트랙트 기술을 도입하는 연구들이 활발하다. 그러나 기존의 연구들은 사고를 입증하기에 미흡한 수준의 교통 사고관련 데이터의 활용으로 악의적인 보험자의 사고 위조, 손상 확대 등의 보험사기 위협에 노출되어 있다. 이를 해결하고자, 본 논문에서는 자동차에 탑재된 센서, RSU, IoT 기기 등을 통한 다양한 종류의 데이터와 차량용 스마트 컨트랙트를 이용하여 사고데이터 기반 신뢰도 산정 모델을 제안한다. 특히 교통사고 데이터의 종류 및 상태에 따라 가중치를 달리하고, 다양한 사고 상황에 따라 학습되는 신뢰도 산정 모델을 고려하여 회귀모델을 적용했다. 제안 모델은 보험 처리과정의 투명성, 보험 처리 과정의 간소화와 같은 기존 장점을 유지하며 효과적인 보험사기 차단, 보험 소송의 감소의 효과를 보일 것으로 기대된다.

• 한국항공우주학회지
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• 제48권7호
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• pp.537-546
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• 2020

우주발사체 개발과정에서 설계와 프로세스의 성능지표로 활용되는 신뢰도는 발사 성공률로 유효성이 확인되고, 반복된 발사를 통해 수집된 데이터는 신뢰도 관리를 위하여 피드백 되어야 한다. 본 논문에서는 전 세계 우주발사체의 발사 이력을 조사하여 발사체 모델이나 발사 운용을 통한 기술 성숙도에 따른 발사 성공률을 비교 분석하였고, 사전정보를 반영한 사전확률분포에 발사를 통해 관측된 데이터를 업데이트하는 베이지안 기법을 적용하여 다음 발사에서 예상되는 성공률을 추정하였다. 여러 유형의 사전확률분포를 사용하여 추정한 발사 성공률과 전통적인 통계 기법을 통해 산출한 성공률을 비교 분석하여 적절한 사전분포를 설정하는 방안을 검토하였고, 베이지안 기법을 적용하여 미래의 발사 성공률을 예측하기 위해 고려할 사항들을 제시하였다.

• Journal of Mechanical Science and Technology
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• 제20권12호
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• pp.2124-2135
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• 2006

In this paper, the reliability estimation of pipelines is performed by employing the probabilistic method, which accounts for the uncertainties in the load and resistance parameters of the limit state function. The FORM (first order reliability method) and the SORM (second order reliability method) are carried out to estimate the failure probability of pipeline utilizing the FAD (failure assessment diagram). And the reliability of pipeline is assessed by using this failure probability and analyzed in accordance with a target safety level. Furthermore, the MCS (Monte Carlo Simulation) is used to verify the results of the FORM and the SORM. It is noted that the failure probability increases with the increase of dent depth, gouge depth, operating pressure, outside radius, and the decrease of wall thickness. It is found that the FORM utilizing the FAD is a useful and is an efficient method to estimate the failure probability in the reliability assessment of a pipeline. Furthermore, the pipeline safety assessment technique with the deterministic procedure utilizing the FAD only is turned out more conservative than those obtained by using the probability theory together with the FAD. The probabilistic method such as the FORM, the SORM and the MCS can be used by most plant designers regarding the operating condition and design parameters.