• Journal of the Korean Society of Safety
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• v.12 no.1
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• pp.113-121
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• 1997

Human reliability attempts to make precise quantitative analyses and predictions of the performance of human-machine(or product) systems. In order to yield more precise human error analysis, precise human error probabilities(HEPs) must be used in the analysis. However, because human behavior is influenced by factors that are called performance shaping factors(PSFs), the effects of PSFs must be considered to obtain precise HEPs, These are called basic HEPs or situation-specific HEPs. This paper presents a theoretical method for obtaining basic HEPs (i.e. , considering PSFs) in quantitative human error analysis. In this method, the weight which characterizes the degree of importance of several PSFs is obtained by the analytic hierarchy process. The quality scores of PSFs in the task situation are obtained by percentile concept. These scores are used in conjunction with the relative Importance weights of PSFs to compute the composite quality percentile score of PSFs in the task situation. Then, a new mapping method of the composite quality percentile score of PSFs into a situation-specific basic HEP is proposed with a numerical example.

• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.373-379
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• 2011

디레이팅 과정은 개발 초기 단계에 제품의 신뢰성을 높이기 위하여 제어 가능한 스트레스 항목에 대해 제한을 두는 것이다. 부품의 열적, 전기적, 기계적 스트레스 등 여러 스트레스에 대해서 실제 부품의 규격보다 낮은 수준으로 사용을 제한하는 것을 디레이팅이라 하며, 부품의 고장률과 수명은 주위의 온도나 전기적 스트레스 등에 의해서 변화하기 때문에 신뢰성을 높이기 위해서는 부품의 사용조건을 최대정격보다 경감해서 사용하는 것이 필요하다. 또한 디레이팅과 고장메커니즘 간에는 밀접한 관계가 있지만 디레이팅이 모든 부품들의 고장률과 스트레스 개선을 똑같이 해주는 것은 아니기 때문에 공학적인 경험이 응용되어야 한다. 본 연구에서는 디레이팅 기법에 대한 최근 연구 동향을 살펴보고 향후 고장메커니즘 분석 및 부하강도 분석을 통한 디레이팅 방법을 연구해 보고자 한다.

• Proceedings of the Safety Management and Science Conference
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• 2012.04a
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• pp.535-545
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• 2012

국내의 많은 기업들은 품질경영시스템인 ISO 9000 시리즈와 식스시그마 등 기업의 품질 및 제품에 대한 품질을 높이기 위해 품질관리, 품질경영에 많은 시간과 비용을 들여왔다. 하지만 품질인증제도와는 달리 제품의 신뢰성에 관한 경영시스템인증을 받으려고 하는 기업은 거의 없는 실정이다. 부품 소재나 제품의 신뢰성을 확보하기 위한 방안으로써 신뢰성경영시스템에 대한 인증은 필수적이라 할 수 있다. 신뢰성 관련 기법들을 표준화하고, 효율적인 경영시스템을 도입하여 운영하고, 여기에 세계적으로 통용되는 기술체계를 도입하여 기업의 신뢰성경영시스템을 발전시킨다면 우리산업이 당면한 수출 경쟁력 확보 등의 현안문제 해결에도 도움이 될 수 있다. 본 연구에서는 신뢰성 경영시스템 인증제도 수립에 있어 국제 표준인 신뢰성경영시스템 IEC 60300에 대해 소개하고, 신뢰성 경영시스템 평가방법을 활용한 MIR기법과 AHP기법을 분석 비교하고, 개선방향을 제시하고자 한다.

• Proceedings of the Safety Management and Science Conference
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• 2006.11a
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• pp.181-191
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• 2006

최근 많은 기업에서 전사적 자원관리 시스템의 보급이 활발히 이루어지고는 있으나, 해당 시스템의 기초데이터라 할 수 있는 생산실적의 수집에 있어 많은 문제점이 발생하고 있다. 생산실적의 늦은 수집은 효율적 기업운영에 치명적이라 할 수 있으며, 이러한 이유로 실시간 생산실적을 수집하는 POP시스템의 도입이 해결방안으로 널리 구축 운용되고 있다. POP시스템의 구축 및 운용에 있어 가장 중요한 사항은 정확한 생산실적의 실시간 수집이라 할 수 있으나, 적지 않은 구축 기업들에서 몇 가지 요인들로 인한 신뢰할 수 없는 데이터의 수집으로 기업 경쟁력을 떨어뜨리는 결과를 보여주고 있다. 본 연구에서는 이러한 요인들을 분석하고 신뢰성을 향상시킬 수 있는 방안을 제시하며, 실제로 적용된 사례를 소개하고자 한다.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2220-2238
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• 2024

As a typical active equipment, pump machinery is widely used in nuclear power plants. Although the mechanism of pump machinery in nuclear power plants is similar to that of conventional pumps, the safety and reliability requirements of nuclear pumps are higher in complex operating environments. Once there is significant performance degradation or failure, it may cause huge security risks and economic losses. There are many pumps mechanical parameters, and it is very important to explore the correlation between multi-dimensional variables and condition. Therefore, a condition monitoring model based on Deep Denoising Autoencoder (DDAE) is constructed in this paper. This model not only ensures low false positive rate, but also realizes early abnormal monitoring and location. In order to alleviate the influence of parameter time-varying effect on the model in long-term monitoring, this paper combined equidistant sampling strategy and DDAE model to enhance the monitoring efficiency. By using the simulation data of reactor coolant pump and the actual centrifugal pump data, the monitoring and positioning capabilities of the proposed scheme under normal and abnormal conditions were verified. This paper has important reference significance for improving the intelligent operation and maintenance efficiency of nuclear power plants.

• Earthquakes and Structures
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• v.20 no.1
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• pp.109-122
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• 2021

Significant progress in the oil and gas industry advances the application of pipeline into an intelligent era, which poses rigorous requirements on pipeline safety, reliability, and maintainability, especially when crossing seismic zones. In general, strike-slip faults are prone to induce large deformation leading to local buckling and global rupture eventually. To evaluate the performance and safety of pipelines in this situation, numerical simulations are proved to be a relatively accurate and reliable technique based on the built-in physical models and advanced grid technology. However, the computational cost is prohibitive, so one has to wait for a long time to attain a calculation result for complex large-scale pipelines. In this manuscript, an efficient and accurate surrogate model based on machine learning is proposed for strain demand prediction of buried X80 pipelines subjected to strike-slip faults. Specifically, the support vector regression model serves as a surrogate model to learn the high-dimensional nonlinear relationship which maps multiple input variables, including pipe geometries, internal pressures, and strike-slip displacements, to output variables (namely tensile strains and compressive strains). The effectiveness and efficiency of the proposed method are validated by numerical studies considering different effects caused by structural sizes, internal pressure, and strike-slip movements.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.2
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• pp.64-74
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• 1997

The necessity and importance of fatigue failure to variable load has been appreciated as the structural design technique develops and use of high tensile steel is increasing. This is much more appreciated for a large ship such as VLCC. The rigorous fatigue analysis and safety assessment should be, hence, carried out at the design stage to avoid the possibility of fatigue failure and to achieve the design result having a sufficient structural safety to fatigue strength. This paper deals with an efficient spectral fatigue analysis of ship structures by introducing the concept of stress influence coefficient. In the process included are probabilistic loading analysis, evaluation of long-term distribution of stress range and estimation of fatigue life applying the spectral fatigue analysis. An integrated computer program has been developed in which reliability analysis to fatigue strength is also included and has been applied to D/H VLCC.

• Journal of The Korea Institute of Healthcare Architecture
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• v.20 no.1
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• pp.7-14
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• 2014

Purpose: In this study, we performed ventilation simulations for a standard isolation ward including three intensive care rooms, one anteroom(buffer room), and its recommended ventilation equipments. The purpose of this study is to predict outflow of pathogenic bacteria from patient breath to verify the reliability and the safety of the isolation ward. Methods: We suppose three scenarios of the movement of medical staff. The leakage of patient's breath to out of the ward is predicted in these scenarios using CFD simulations. Results: The patient's breath leakage rate to out of the ward in scenario 1 according to room air changes per hour(ACH : 6 and 12) is predicted to be 0.000057% and 0.00002%, respectively. The patient's breath leakage rate to out of the ward in scenario 2 according to room air changes(ACH : 6 and 12) is predicted to be 0.00063% and 0.00019%, respectively. The patient's breath leakage rate to out of the ward in scenario 3, which is the worst case(6 room air changes) is predicted to be 0.1%. Implications: Through the ventilation simulation like that in this study, the reliability and the safety on isolation performance of various plan of isolation ward are predicted quantitatively.

• Nuclear Engineering and Technology
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• v.21 no.1
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• pp.1-11
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• 1989

Numerous losses of decay heat removal capability have occurred at U during stutodwn while its significance to safety is needless to say. A study is carried out as an attempt to assess what could be done to lower the frequency of these events and to mitigate their consequences in the unlikely event that one occurs. The shutdown risk model is developed and analyzed using Event/Fault Tree for the typical pressurized water reactor. The human cognitive reliability (HCR) model, two-stage bayesian approach and staircase function model are used to estimate human reliability, initiating event frequency and offsite power non-recovery probability given loss of offsite power, respectively. The results of this study indicate that the risk of a Pm at shutdown is not much lower than the risk when the plant is operating. By examining the dominant accident sequences obtained, several design deficiencies are identified and it is found that some proposed changes lead to significant reduction in core damage frequency due to loss of cooling events.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.175-189
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• 2023

Fault detection and diagnosis (FDI) algorithms are actively being researched for ensuring the integrity and reliability of environment perception sensors in autonomous vehicles. In this paper, a fault detection algorithm based on a multi-sensor perception system composed of radar, camera, and lidar is proposed to guarantee the safety of an autonomous vehicle's perception system. The algorithm utilizes reference generation filters and residual generation filters based on finite impulse response (FIR) filter estimates. By analyzing the residuals generated from the filtered sensor observations and the estimated state errors of individual objects, the algorithm detects faults in the environment perception sensors. The proposed algorithm was evaluated by comparing its performance with a Kalman filter-based algorithm through numerical simulations in a virtual environment. This research could help to ensure the safety and reliability of autonomous vehicles and to enhance the integrity of their environment perception sensors.