• 한국안전학회지
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• 제28권1호
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• pp.74-80
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• 2013

This study describes structural reliability analysis of actively-controlled structure for which random vibration analysis is incorporated into the first-order reliability method (FORM) framework. The existing approaches perform the reliability analysis based on the RMS response, whereas the proposed study uses the peak response for the reliability analysis. Therefore, the proposed approach provides us a meaningful performance measure of the active control system, i.e., realistic failure probability. In addition, it can deal with the uncertainties in the system parameters as well as the excitations in single-loop reliability analysis, whereas the conventional random vibration analysis requires double-loop reliability analysis; one is for the system parameters and the other is for stochastic excitations. The effectiveness of the proposed approach is demonstrated through a numerical example where the proposed approach shows fast and accurate reliability (or inversely failure probability) assessment results of the dynamical active control system against random seismic excitations in the presence of parametric uncertainties of the dynamical structural system.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.41-49
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• 2010

In this paper, we propose a hierarchical RAM simulation model framework which are used to analyze the RAM specifications on the concept refinement phase. The hierarchical RAM simulation model framework consists of RAM simulation models, class library and each model's input and output data lists. The hierarchical RAM simulation models are co-operated with 3 kinds of model - type I, II, III. Type I, II models are used to analyze the target operational availability and Type III is used to establish the initial RAM specifications. Each model's input and output data lists are defined by considering each model's purpose of RAM analysis. The class library is arranged with each model's classes for implementing the hierarchical simulation models. The proposed framework may be applied for executing the RAM activities effectively.

• 대한조선학회논문집
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• 제60권2호
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• pp.95-109
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• 2023

In the 4th industrial revolution, changes in the technological paradigm have had a direct impact on the maintenance system of ships. The 2-stroke low speed engine system integrates with the core equipment required for propulsive power. The Condition Based Management (CBM) is defined as a technology that predictive maintenance methods in existing calender-based or running time based maintenance systems by monitoring the condition of machinery and diagnosis/prognosis failures. In this study, we have established a framework for CBM technology development on our own, and are engaged in engineering-based failure analysis, data development and management, data feature analysis and pre-processing, and verified the reliability of failure mode DB using LSTM algorithms. We developed various simulated failure mode scenarios for 2-stroke low speed engine and researched to produce data on onshore basis test_beds. The analysis and pre-processing of normal and abnormal status data acquired through failure mode simulation experiment used various Exploratory Data Analysis (EDA) techniques to feature extract not only data on the performance and efficiency of 2-stroke low speed engine but also key feature data using multivariate statistical analysis. In addition, by developing an LSTM classification algorithm, we tried to verify the reliability of various failure mode data with time-series characteristics.

• 한국IT서비스학회지
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• 제19권3호
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• pp.151-163
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• 2020

This paper describes a study on the FRACAS(Failure Reporting Analysis and Corrective Action System)-based dependability control platform for domestic urban railway trains. There are more demands for the verification of the dependability of trains as it becomes a regulation for train manufacturers to verify the dependability recently. Train manufacturers as well as railway operators need a effective FRACAS solution to perform the verification of the dependability. Yet current FRACAS solutions have limitations to support the verification processes effectively. This paper addresses the issues of current FRACAS solutions and suggests a FRACAS framework designed for the domestic urban railway trains. Service failure scenarios are standardized using the proposed availability model to implement a more user-friendly and reliable platform. A new FRACAS-based platform for the dependability control (SCARF^®) has been developed to implement the suggested framework. The detail interfaces and functions of the platform are explained. The SCARF^® platform is expected to engage the increasing demands for the dependability control successfully enhancing the reliability, maintainability, availability and safety of domestic urban railway trains eventually.

• Composites Research
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• 제30권1호
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• pp.52-58
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• 2017

본 논문에서 제시한 복합재 날개 구조물의 최적설계 기법은 파손모드를 통합한 최적화 프레임 웍을 사용하여 복합재 날개 구조물의 안전율을 자동으로 계산한다. 개발된 최적화 프레임 웍은 복합재 구조물의 설계요소에 가장 큰 영향을 주는 파손모드 즉, 최초 파손모드, 좌굴 파손 모드 및 베어링-바이패스 파손을 확인하여 구축된 적층 데이터베이스 안에서 적층수를 찾아낸다. 이는 개발과정에서 수정 및 반복되는 설계 및 해석 시간을 단축시킬 수 있는 효과가 있다. 설계변수는 계단형태로 이루어진 적층 데이터베이스이며 응답은 변형률, 좌굴, 볼트 주변부의 응력장이며 목적함수는 날개구조의 질량이다. 그리고 최적화 프레임 윅을 구동하는 Composite Optimizer의 해석결과를 검증하기 위하여 유한요소모델의 좌굴해석 결과와 비교하여 유효성을 검증하였다.

• 한국지반공학회논문집
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• 제25권6호
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• pp.59-72
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• 2009

대구경 해상 말묵의 수평 하중전이 거동 및 변형 해석을 위해 p-y 하중전이 해석법이 널리 사용되고 있다. 그러나, 본 연구에서는, 기존의 p-y 해석법의 단점을 극복하여, 지반의 연속성을 고려한 수평방향 하중전이 해석을 고찰하였으며, 3D wedge failure mode의 이론적인 해법과 재하시험을 통해 말뚝의 실제 거동에 보다 부합되도록 연약지반의 p-y 곡선을 제안하였다. 제안된 하중전이함수법의 타당성을 검증하기 위하여 현장재하시험 사례와의 비교분석을 수행하였고, 그 결과 제안된 해석방법은 기존 p-y 곡선에 비해 대구경 해상말뚝의 거동 및 변형 특성을 적절히 예측함을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제39권1호
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• pp.51-62
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• 2007

To efficiently design safety-critical systems such as nuclear power plants, with the requirement of high reliability, methodologies allowing for rigorous interactions between the synthesis and analysis processes have been proposed. This paper attempts to develop a reliability-centered design framework through an interactive process between Axiomatic Design (AD) and Fault Tree Analysis (FTA). Integrating AD and FTA into a single framework appears to be a viable solution, as they compliment each other with their unique advantages. AD provides a systematic synthesis tool while FTA is commonly used as a safety analysis tool. These methodologies build a design process that is less subjective, and they enable designers to develop insights that lead to solutions with improved reliability. Due to the nature of the two methodologies, the information involved in each process is complementary: a success tree versus a fault tree. Thus, at each step a system using AD is synthesized, and its reliability is then quantified using the FT derived from the AD synthesis process. The converted FT provides an opportunity to examine the completeness of the outcome from the synthesis process. This study presents an example of the design of a Containment Heat Removal System (CHRS). A case study illustrates the process of designing the CHRS with an interactive design framework focusing on the conversion of the AD process to FTA.

• Wind and Structures
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• 제22권5호
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• pp.543-553
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• 2016

The growing complexity of modern technological systems requires more flexible and powerful reliability analysis tools. Existing tools encounter a number of limitations including lack of modeling power to address components interactions for complex systems and lack of flexibility in handling component failure distribution. We propose a reliability modeling framework based on the Bayesian network (BN). It can combine historical data with expert judgment to treat data scarcity. The proposed methodology is applied to wind turbines reliability analysis. The observed result shows that a BN based reliability modeling is a powerful potential solution to modeling and analyzing various kinds of system components behaviors and interactions. Moreover, BN provides performing several inference approaches such as smoothing, filtering, what-if analysis, and sensitivity analysis for considering system.

• 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.

• 한국건설관리학회논문집
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• 제6권1호
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• pp.195-204
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• 2005

건설실패정보는 건설실패를 야기한 업무 프로세스를 파악하고, 건설실패를 예방할 수 있는 향상된 프로세스를 제공하는 핵심 요인이 될 수 있다. 본 연구에서는 건설실패정보를 활용하여, 건설실패의 재발을 예방할 수 있는 건설 프로세스의 지속적 개선 모델의 개념적 틀을 제시하였다. 문헌연구를 통해 건설실패의 정의, 유형, 원인 및 교훈 등의 건설실패정보에 대한 개념을 정립하였다. 또한 건설실패정보에 프로세스 재설계 방법론 및 사례기반추론기법을 적용하여 프로세스 개선에의 적용가능성을 확인하였고, 사례기반추론기법의 주요 모듈인 사례검색, 사례색인 및 사례적응을 이용한 건설 프로세스의 지속적 개선 모델의 개념적 틀을 제시하였다.