http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Model-based localization and mass-estimation methodology of metallic loose parts
Moon, Seongin,Han, Seongjin,Kang, To,Han, Soonwoo,Kim, Munsung Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4
A loose part monitoring system is used to detect unexpected loose parts in a reactor coolant system in a nuclear power plant. It is still necessary to develop a new methodology for the localization and mass estimation of loose parts owing to the high estimation error of conventional methods. In addition, model-based diagnostics recently emphasized the importance of a model describing the behavior of a mechanical system or component. The purpose of this study is to propose a new localization and mass-estimation method based on finite element analysis (FEA) and optimization technique. First, an FEA model to simulate the propagation behavior of the bending wave generated by a metal sphere impact is validated by performing an impact test and a corresponding FEA and optimization for a downsized steam-generator structure. Second, a novel methodology based on FEA and optimization technique was proposed to estimate the impact location and mass of a loose part at the same time. The usefulness of the methodology was then validated through a series of FEAs and some blind tests. A new feature vector, the cross-correlation function, was also proposed to predict the impact location and mass of a loose part, and its usefulness was then validated. It is expected that the proposed methodology can be utilized in model-based diagnostics for the estimation of impact parameters such as the mass, velocity, and impact location of a loose part. In addition, the FEA-based model can be used to optimize the sensor position to improve the collected data quality in the site of nuclear power plants.
Impact parameter prediction of a simulated metallic loose part using convolutional neural network
Moon, Seongin,Han, Seongjin,Kang, To,Han, Soonwoo,Kim, Kyungmo,Yu, Yongkyun,Eom, Joseph Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.4
The detection of unexpected loose parts in the primary coolant system in a nuclear power plant remains an extremely important issue. It is essential to develop a methodology for the localization and mass estimation of loose parts owing to the high prediction error of conventional methods. An effective approach is presented for the localization and mass estimation of a loose part using machine-learning and deep-learning algorithms. First, a methodology was developed to estimate both the impact location and the mass of a loose part at the same times in a real structure in which geometric changes exist. Second, an impact database was constructed through a series of impact finite-element analyses (FEAs). Then, impact parameter prediction modes were generated for localization and mass estimation of a simulated metallic loose part using machine-learning algorithms (artificial neural network, Gaussian process, and support vector machine) and a deep-learning algorithm (convolutional neural network). The usefulness of the methodology was validated through blind tests, and the noise effect of the training data was also investigated. The high performance obtained in this study shows that the proposed methodology using an FEA-based database and deep learning is useful for localization and mass estimation of loose parts on site.
원전기기 금속이물질 충격현상 모사 및 빅데이터 생산을 위한 자동해석시스템 개발
문성인(Seongin Moon),강토(To Kang),한순우(Soonwoo Han) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
A loose-part monitoring system (LPMS) is used to detect loose-parts in the reactor coolant system in nuclear power plant. For identifying the impact source, it is important to provide accurate information on impact response. Recently, a model-based diagnostics emphasize the importance of a model describing the behaviors of a mechanical system or component. Also, thanks to increasing computing power, finite element analysis (FEA) method recently beaome an available option to calculate reliable impact response behavior. In this paper, a FEA model to simulate the propagation behavior of the bending wave, generated by a metal ball impact, is validated by performing impact tests and the corresponding finite element analyses for a flat plate and a downsized steam generator structure. A novel methodology based on FEA was proposed to estimate the mass and the impact location of a loose-part, and then the usefulness of the methodology was validated through a series of FEAs. Also, an automated impact analysis system for FEA-based big data construction was developed. It is expected that the proposed methodology and the big data can be utilized in model-based diagnostics for estimation of impact parameters such mass, velocity and impact location of a loose-part in nuclear power plants.
유한요소해석 기반 충격하중에 의한 평판 구조물 내 굽힘파 전파거동 분석
문성인(Seongin Moon),강토(To Kang),한순우(Soon Woo Han),이정한(Jeong Han Lee),박진호(Jin Ho Park) 한국비파괴검사학회 2018 한국비파괴검사학회지 Vol.38 No.3
금속이물질(loose part)에 의한 충격현상은 원자로냉각제계통의 구조건전성에 영향을 미칠 수 있는 주요요인 중 하나이며, 금속이물질의 질량추정은 원자력발전소의 안전운전을 위해 필수적인 기술이다. 금속이물질의 질량을 정확하게 추정하기 위해서는 충격하중 하에서 구조물내 굽힘파(bending wave) 전파거동을 정확하게 모사할 수 있어야 한다. 현재 임의의 충격하중에 대한 Lamb의 일반해 및 Hertz의 충격이론은 금속이물질의 충격에 의해 발생되는 굽힘파의 특성을 분석하기 위해 사용되고 있지만, 금속이물질 충돌에 의해 발생하는 가속도 응답에 대한 정확한 정보를 제공할 수 없다. 본 연구에서는 충격하중에 의해 발생되는 굽힘파를 모델링하기 위한 FEA 기법을 검토하였다. 또한, FEA에 기반하여 평판의 두께와 특성길이(충격입력 지점으로 부터 굽힘파가 형성되기 까지 필요한 충격파의 전파거리) 사이의 상관관계를 제안하였다. Loose parts can cause component damages in nuclear power plants; thus, the mass estimation of loose parts is crucial in safety management. To accurately estimate the mass of loose parts, it is essential to precisely simulate the bending wave propagation behavior in a structure under impact loading. Lamb’s general solution for an arbitrary impact force function and Hertz impact theory have been used to identify the characteristics of the bending wave impacted by a metallic loose part. However, these approaches cannot provide accurate information on acceleration response. In this study, the bending wave propagation behavior in plate structures under impact loading by a simulated loose part (metal sphere) was modeled using the finite element analysis (FEA) technique. The impact response characteristics of the impact response signal from a metal sphere were analyzed by FEA and was verified with experimental results. In addition, the correlation between the plate thickness and characteristic length of the plate was presented.