• 터널과지하공간
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• 제10권1호
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• pp.33-44
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• 2000

이 연구에서는 지하공동의 점진적인 붕락이 지표침하에 미치는 영향을 조사하기 위하여, 주문진산 표준사를 이용하여 모형지반을 구성하였으며, 공동의 심도를 달리하는 6가지 모델에 대하여 실내 모형실험을실시하였다. 여기서 공동의 심도와 붕락구간의 크기에 따른 침하발생양상을 조사하였다. 또한 NCB 방법, 지수함수를 이용한 윤곽함수법 영향함수법 등의 침하예측방법을 이용하여 모형실험으로부터 측정된 수직 및 수평변위를 해석하였으며, 모래지반에 적합한 침하예측방법을 제안하였다.

• Geomechanics and Engineering
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• 제22권4호
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• pp.291-303
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• 2020

The deformation of the rock surrounding a tunnel manifests due to the stress redistribution within the surrounding rock. By observing the deformation of the surrounding rock, we can not only determine the stability of the surrounding rock and supporting structure but also predict the future state of the surrounding rock. In this paper, we used grey system theory to analyse the factors that affect the deformation of the rock surrounding a tunnel. The results show that the 5 main influencing factors are longitudinal wave velocity, tunnel burial depth, groundwater development, surrounding rock support type and construction management level. Furthermore, we used seismic prospecting data, preliminary survey data and excavated section monitoring data to establish a neural network learning model to predict the total amount of deformation of the surrounding rock during tunnel collapse. Subsequently, the probability of a change in deformation in each predicted section was obtained by using a Bayesian method for detecting change points. Finally, through an analysis of the distribution of the change probability and a comparison with the actual situation, we deduced the survey mark at which collapse would most likely occur. Surface collapse suddenly occurred when the tunnel was excavated to this predicted distance. This work further proved that the Bayesian method can accurately detect change points for risk evaluation, enhancing the accuracy of tunnel collapse forecasting. This research provides a reference and a guide for future research on the probability analysis of tunnel collapse.

• 지질공학
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• 제30권4호
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• pp.663-671
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• 2020

최근 국내에서는 산림지역 뿐만 아니라 대도시지역에서도 자연재해가 많이 발생하고 있으며, 이에 대한 국가적인 요구사항은 증가하고 있다. 특히 국도 비탈면 붕괴에 대하여 체계적으로 관리할 수 있는 사전 재해정보 시스템은 전무한 실정이다. 본 연구에서는 CSMS(Cut Slope Management System)에서 관리하는 강원도와 경상도 지역의 국도 비탈면 붕괴 정밀조사 보고서와 비탈면 기초조사를 토대로 비탈면 붕괴 유발 인자에 대한 빅데이터 분석을 실시하였다. 분석 결과를 바탕으로 붕괴 비탈면 위치와 기상정보를 반영하여 분류 기반 머신러닝 모형인 Adaboost를 통한 비탈면 붕괴 위험도 예측모형을 구축하였다. 또한 시각화 프로그램인 비탈면 붕괴 위험도 시각화 지도를 개발하여 기상여건 변화에 따른 비탈면 위험도 파악을 통한 선제적 재해재난 예방대책에 활용할 수 있음을 보여주고 있다.

• 대한기계학회논문집A
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• 제29권5호
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• pp.754-761
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• 2005

The 40\% of wall thickness criterion which has been used as a plugging rule of steam generator tubes is applicable only to a single cracked tube. In the previous studies performed by authors, several global failure prediction models were introduced to estimate the failure loads of steam generator tubes containing two adjacent parallel axial through-wall cracks. These models were applied for thin plates with two parallel cracks and the COD base model was selected as the optimum one. The objective of this study is to verify the applicability of the proposed optimum global failure prediction model for real steam generator tubes with two parallel axial through-wall cracks. For the sake of this, a series of plastic collapse tests and finite element analyses have been carried out fur the steam generator tubes with two machined parallel axial through-wall cracks. Thereby, it was proven that the proposed optimum failure prediction model can be used as the best one to estimate the failure load quite well. Also, interaction effects between two adjacent cracks were assessed through additional finite element analyses to investigate the effect on the global failure behavior.

• 한국구조물진단유지관리공학회 논문집
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• 제21권5호
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• pp.108-116
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• 2017

본 연구는 연쇄붕괴 저항성능 평가 시 기둥의 순간적인 제거에 따른 동적효과가 반영된 에너지 기반 근사해석의 적용성을 확인하기 위해 내진 설계된 철골모멘트골조의 예제구조물을 대상으로 분석하였으며, 이를 통해 구조 강건성을 산정하여 연쇄붕괴에 대한 민감도를 평가할 수 있는 방법을 제시하였다. 예제구조물에 대한 적용을 통해 비선형 정적해석 결과를 이용한 에너지 기반 근사해석과 직접동적해석에 대한 결과가 잘 일치하는 것을 검증하였으며, 다른 구조시스템을 가지는 건물의 연쇄붕괴에 대한 구조적 내력성능을 비교하기 위한 수단으로 구조물의 민감도를 평가하였다. 이는 비정상하중에 대하여 구조물이 연쇄붕괴에 저항할 수 있는 최대보유 잔류내력 성능인 구조 강건성을 이용하였고, 본 연구에서 제시한 방법을 통해 연쇄붕괴 해석 및 설계에 편리하게 활용될 수 있음을 확인하였다.

• Structural Engineering and Mechanics
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• 제78권4호
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• pp.485-496
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• 2021

So far analytical methods on collapse assessment of three-dimensional (3-D) steel frames have mainly focused on a single-column-removal scenario. However, the collapse of the Federal Building in the US due to car bomb explosion indicated that the loss of multiple columns may occur in the real structures, wherein the structures are more vulnerable to collapse. Meanwhile, the General Services Administration (GSA) in the US suggested that the removal of side columns of the structure has a great possibility to cause collapse. Therefore, this paper analytically deals with the robustness of 3-D steel frames in a two-side-column-removal (TSCR) scenario. Analytical method is first proposed to determine the collapse resistance of the frame during this column-removal procedure. The reliability of the analytical method is verified by the finite element results. Moreover, a design-based methodology is proposed to quickly assess the robustness of the frame due to a TSCR scenario. It is found the analytical method can reasonably predict the resistance-displacement relationship of the frame in the TSCR scenario, with an error generally less than 10%. The parametric numerical analyses suggest that the slab thickness mainly affects the plastic bearing capacity of the frame. The rebar diameter mainly affects the capacity of the frame at large displacement. However, the steel beam section height affects both the plastic and ultimate bearing capacity of the frame. A case study on a six-storey steel frame shows that the design-based methodology provides a conservative prediction on the robustness of the frame.

• Earthquakes and Structures
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• 제11권5호
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• pp.779-807
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• 2016

Ground Motion Prediction Equations (GMPEs) are essential tools in seismic hazard analysis. With the introduction of probabilistic approaches for the estimation of seismic response of structures, also known as, performance based earthquake engineering framework; new tasks are defined for response spectrum such as the reference criterion for effective structure-specific selection of ground motions for nonlinear time history analysis. One of the recent efforts to introduce a high quality databank of ground motions besides the corresponding selection scheme based on the broadband spectral consistency is the development of SIMBAD (Selected Input Motions for displacement-Based Assessment and Design), which is designed to improve the reliability of spectral values at all natural periods by removing noise with modern proposed approaches. In this paper, a new global GMPE is proposed by using selected ground motions from SIMBAD to improve the reliability of computed spectral shape indicators. To determine regression coefficients, 204 pairs of horizontal components from 35 earthquakes with magnitude ranging from Mw 5 to Mw 7.1 and epicentral distances lower than 40 km selected from SIMBAD are used. The proposed equation is compared with similar models both qualitatively and quantitatively. After the verification of model by several goodness-of-fit measures, the epsilon values as the spectral shape indicator are computed and the validity of available prediction equations for correlation of the pairs of epsilon values is examined. General consistency between predictions by new model and others, especially, in short periods is confirmed, while, at longer periods, there are meaningful differences between normalized residuals and correlation coefficients between pairs of them estimated by new model and those are computed by other empirical equations. A simple collapse assessment example indicate possible improvement in the correlation between collapse capacity and spectral shape indicators (${\varepsilon}$) up to 20% by selection of a more applicable GMPE for calculation of ${\varepsilon}$.

• 한국농공학회논문집
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• 제59권5호
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• pp.101-108
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• 2017

Recently, the occurrence of landslides has been increasing over the years due to the extreme weather event. Developments of landslides monitoring technology that reduce damage caused by landslide are urgently needed. Therefore, in this study, a strain ratio sensor was developed to predict the ground behavior during the slope failure, and the change in surface ground displacement was observed as slope failed on the field model experiment. As a result, in the slope failure, the ground displacement process increases the risk of collapse as the inverse displacement approaches zero. It is closely related to the prediction of precursor. In all cases, increase in displacement and reverse speed of inverse displacement with time was observed during the slope failure, and it is very important event for monitoring collapse phenomenon of risky slopes. In the future, it can be used as disaster prevention technology to contribute in reduction of landslide damage and activation of measurement industry.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.5115-5122
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• 2013

본 논문은 급경사지(산사태 및 사면붕괴, 축대 등)붕괴 등으로 인하여 많은 생명과 재산피해 방지를 목적으로 붕괴 위험성을 감지하고 신속히 대응을 할 수 있도록 하기 위하여 u-IT기반의 급경사지 붕괴예측 감시용 실시간 모니터링 시스템을 개발하였다. 급경사지붕괴 감시에 중요한 계측기로서 강우량 계측기, 간극수압 계측기, 지표변위 계측기, 지중경사 계측기, 함수비계측기, 영상분석 계측기 등을 선정하고 테스트베드에 적용하였다. 각 계측기의 신뢰성 검증에 필요한 동작기능 및 성능확인은 현장에 설치된 계측기 별로 실험을 통하여 확인하였다. 본 연구에서 개발한 급경사지붕괴 감지를 위한 USN기반의 실시간 급경사지 모니터링 시스템을 급경사지 붕괴감지뿐만 아니라 도로변 절개사면과 암반사면 등에 상시계측을 통하여 붕괴위험 예측에도 적용할 수 있으므로 인명피해와 재산피해를 최소할 수 있을 것으로 판단되며, 이 시스템은 본 연구의 시범적용 결과를 바탕으로 급경사지 전역에 확산될 계획에 있다.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.485-494
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• 2016

The risk-based assessment, also called time-based assessment of structure is usually performed to provide seismic risk evaluation of a target structure for its entire life-cycle, e.g. 50 years. The prediction of collapse probability is the estimator in the risk-based assessment. While the risk-based assessment is the key in the performance-based earthquake engineering, its application is very limited because this evaluation method is very expensive in terms of simulation and computational efforts. So the evaluation database for many archetype structures usually serve as representative of the specific system. However, there is no such an assessment performed for building stocks in Korea. Consequently, the performance objective of current building code, KBC is not clear at least in a quantitative way. This shortcoming gives an unresolved issue to insurance industry, socio-economic impact, seismic safety policy in national and local governments. In this study, we evaluate the comprehensive seismic performance of an low-rise residential buildings with discontinuous structural walls, so called piloti-type structure which is commonly found in low-rise domestic building stocks. The collapse probability is obtained using the risk integral of a conditioned collapse capacity function and regression of current hazard curve. Based on this approach it is expected to provide a robust tool to seismic safety policy as well as seismic risk analysis such as Probable Maximum Loss (PML) commonly used in the insurance industry.