• 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.

• 한국공간구조학회논문집
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• 제18권2호
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• pp.87-97
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• 2018

Stone pagoda structures have continued to be aged due to the combination of various damage factors. However, some studies on nonstructural damage have been carried out, but assessment studies on structural damage have not been done in various ways. Therefore, in this study, structural and nonstructural influencing factors according to the damage types are classified and the damage assessment according to the structural influencing factors affecting the behavior of the stone pagoda structure is performed. In addition, the damage rating classification criteria for each type of structural damages or damage locations are presented, and the damage index is calculated by providing the criteria for the classification of damage according to the degree of damage to which the damage is caused. Therefore, this study can evaluate quantitatively the damage status of stone pagoda structures.

• 한국지진공학회논문집
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• 제25권6호
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• pp.283-292
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• 2021

In this study, a structural health monitoring system for cable-stayed bridges is developed. In the system, condition assessment of the structure is performed based on measured records from seismic accelerometers. Response indices are defined to monitor structural safety and serviceability and derived from the measured acceleration data. The derivation process of the indices is structured to follow the transformation from the raw data to the outcome. The process includes noise filtering, baseline correction, numerical integration, and calculation of relative differences. The system is packed as a condition assessment program, which consists of four major processes of the structural health evaluation: (i) format conversion of the raw data, (ii) noise filtering, (iii) generation of response indices, and (iv) condition evaluation. An example set of limit states is presented to evaluate the structural condition of the test-bed and cable-stayed bridge.

• 전산구조공학
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• 제10권2호
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• pp.189-201
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• 1997

국내 보도육교의 경우, 단순한 구조형식과 공장제작에 의한 현장조립의 신속한 시공 및 유지관리상의 장점들로 인하여 표준화된 강상형 보고육교가 교통혼잡이 심한 도심지와 각종 국도상에 다수 건설되어 왔지만, 이중 상당수의 육교가 공용년수 증가와 더불어 열화손상되어 안전도 및 사용성이 매우 불량한 상태에 있다. 본 논문에서는 열화손상된 기존의 강상형 보도육교의 실제적인 안전도 및 잔존내하력을 평가하기 위하여 선진각국에서는 이미 일반화되고 있는 von Mises'조합응력항복기준에 기반을 둔 한계상태설계법에 기초하여 각 구조부위의 항복 및 좌굴에 대한 각각의 비선형 한계상태모형을 제안하고 이를 실구조물에 적용해서 안전도평가 및 신뢰성평가를 수행하여 제안된 모형의 타당성을 고찰하였다. 뿐만아니라 노후된 기존 강상형 보도육교에 대한 현장재하시험 방법과 이들 시험결과를 이용한 실용적이고 합리적인 잔존내하력 평가방법을 제안하고 각국 시방서별/설계방법별로 비교, 고찰하였다.

• 대한조선학회논문집
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• 제30권4호
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• pp.83-92
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• 1993

본고에서는 type B 독립구형 MRV 방식 LNG탱크의 극저온에 대한 구조안전성 평가기법을 연구 하였다. 여기에는 다음과 같은 3가지의 검토과정이 포함된다. 1) 탱크판을 관통하는 균열의 진전과정에서 누설되는 LNG의 양을 추정하고, 이에 따른 선체구조의 안전성을 보장하기 위하여 2차방벽의 설치범위를 결정한다. 2) 구형 LNG탱크시스템에 대한 정상상태 열전달해석 모형을 이용하여 화물창 및 스커트에 대한 온도분포해석을 수행하였다. 3) (2)항의 해석결과 가장 급격한 온도변화를 보이는 탱크와 스커트시스템의 연결부에 대한 열응력의 분포를 해석하였다.

• Smart Structures and Systems
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• 제24권6호
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• pp.693-707
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• 2019

This paper proposes an integrated safety assessment method that can take multiple sources data into consideration based on a data fusion approach. Data cleaning using the Kalman filter method (KF) was conducted first for monitoring data from each sensor. The inclination data from the four tilt sensors of the same monitoring section have been associated to synchronize in time. Secondly, the finite element method (FEM) model was established to physically correlate the external forces with various structural responses of the shield tunnel, including the measured inclination. Response surface method (RSM) was adopted to express the relationship between external forces and the structural responses. Then, the external forces were updated based on the in situ monitoring data from tilt sensors using the extended Kalman filter method (EKF). Finally, mechanics parameters of the tunnel lining were estimated based on the updated data to make an integrated safety assessment. An application example of the proposed method was presented for an urban tunnel during a nearby deep excavation with multiple source monitoring plans. The change of tunnel convergence, bolt stress and segment internal forces can also be calculated based on the real time deformation monitoring of the shield tunnel. The proposed method was verified by predicting the data using the other three sensors in the same section. The correlation among different monitoring data has been discussed before the conclusion was drawn.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.381-396
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• 2020

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part I, finite element (FE) models establishment and validations for both the aircrafts and NPP buildings are performed. (i) Airbus A320 and A380 aircrafts are selected as the representative medium and large commercial aircrafts, and the corresponding fine FE models including the skin, beam, fuel and etc. are established. By comparing the numerically derived impact force time-histories with the existing published literatures, the rationality of aircrafts models is verified. (ii) Fine FE model of the Chinese Zhejiang Sanao NPP buildings is established, including the detailed structures and reinforcing arrangement of both the containment and auxiliary buildings. (iii) By numerically reproducing the existing 1/7.5 scaled aircraft model impact tests on steel plate reinforced concrete (SC) panels and assessing the impact process and velocity time-history of aircraft model, as well as the damage and the maximum deflection of SC panels, the applicability of the existing three concrete constitutive models (i.e., K&C, Winfrith and CSC) are evaluated and the superiority of Winfrith model for SC panels under deformable missile impact is verified. The present work can provide beneficial reference for the integral aircraft crash analyses and structural damage assessment in the following two parts of this paper.

• Structural Engineering and Mechanics
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• 제65권6호
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• pp.751-760
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• 2018

Damages in concrete structures due to aging and other factors could be a serious and immense matter. Making the best selection of the most viable and practical repairing and strengthening techniques are relatively difficult tasks using traditional methods of structural analyses. This is due to the fact that the traditional methods used for assessing aging structure are not fully capable when considering the randomness in strength, loads and cost. This paper presents a reliability-based methodology for assessing reinforced concrete members. The methodology of this study is based on probabilistic analysis, using statistics of the random variables in the performance function equations. Principles of reliability updating are used in the assessment process, as new information is taken into account and combined with prior probabilistic models. The methodology can result in a reliability index ${\beta}$ that can be used to assess the structural component by comparing its value with a standard value. In addition, these methods result in partial safety factor values that can be used for the purpose of strengthening the R/C elements of the existing structure. Calculations and computations of the reliability indices and the partial safety factors values are conducted using the First-order Reliability Method and Monte Carlo simulation.

• 한국전산구조공학회논문집
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• 제28권3호
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• pp.241-248
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• 2015

원자력발전소에는 전력생산과 안전과 관련된 수많은 기기들이 존재하고 있다. 기본적으로 원자력발전소의 구조물과 기기는 지진시 탄성거동올 목표로 안전율을 매우 높게 적용하여 설계해 왔다. 그러나 최근 발생한 지진의 규모가 증가함에 따라 설계수준을 초과한 지진에 대한 기기의 안전성을 재평가할 필요가 있다. 본 연구에서는 구조물의 비선형 거동에 의한 층응답을 분석하였고, 비선형해석에 의한 구조물의 비탄성구조응답계수를 재평가하였다. 기기의 지진취약도 평가시 구조물의 비탄성구조응답이 어떤 영향을 주는지 분석하기 위하여 재평가된 구조물의 비탄성구조응답계수와 기존에 사용되어온 구조물 비탄성구조응답계수를 적용하여 지진취약도 평가를 수행하였다. 해석결과에 따르면 비탄성구조응답계수는 기기의 고유진동수, 기기의 위치 그리고 구조물의 동특성에 따라 영향을 받는 것으로 나타났다.

• 한국강구조학회 논문집
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• 제19권5호
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• pp.515-526
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• 2007

본 연구에서는 시공간의 구조안전도 확보와 교량붕괴를 방지하기 위해 FCM과 FSM공법으로 가설되는 강-콘크리트 복합사장교의 안전도평가 모형을 제안하였다. 구조물의 저항과 하중효과에 내제된 각종 불확실성을 합리적으로 고려하는 구조신뢰성이론에 의해 강합성거더와 콘크리트거더가 연결된 강-콘크리트 복합사장교의 저항과 하중의 분포특성을 정의하고 가설중 영구구조물과 가설구조물의 강도한계상태방정식을 제안하였다. 케이블, 주탑, 거더, 강-콘크리트 접합부 및 가설벤트의 신뢰성해석을 위해 AFOSM 알고리즘과 MCS 기법을 사용하였다. 또한, 가설단계별 구조시스템에 따라 요소신뢰성해석을 수행하였다. 제안된 평가모형의 타당성과 실용성을 검증하기 위하여 제시된 방법을 실제 교량에 적용하였다. 유사한 교량의 안전도 관리를 위한 중점 항목을 정의하기 위해서 주요 인자에 대한 민감도 분석이 수행되었다. 본 연구를 통해, 제안된 모형은 FCM과 FSM으로 가설되는 강-콘크리트 복합사장교의 시공간 안전도 평가를 위한 합리적이고 실용적인 방법으로 적용될 수 있을 것으로 판단되었다.