• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.124-131
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• 2000

Numerical analysis of slop stability is carried out using seismic intensity, modified seismic intensity, and response seismic coefficient methods. It is found by comparing each of method that minimum safety factor precedes the required safety factor. It is also proved during analysis that most conservative method is the earthquake response analysis method, next is the response seismic coefficient method, and last one is the seismic intensity method. Usually, seismic intensity method is applied in analysis of slop stability. However, in view of safety factor, modified seismic intensity method is more conservative than seismic intensity method. Also modified seismic intensity method is appropriate when height of structure analyzed is high enough.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.440-447
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• 2000

In order to evaluate the cost effectiveness of seismic isolation for bridges in low and moderate seismic region, a method of calculation minimum life-cycle cost of seismic-isolated bridges under specific acceleration level and soil condition is developed. Input ground motion is modeled as spectral density function compatible with response spectrum for combination of acceleration coefficient and site coefficient. Failure probability is calculated by spectrum analysis based on random vibration theories to simplify repetitive calculations in the minimization procedure. Ductility of piers and its effects on cost effectiveness are considered by stochastic linearization method. Cost function and cost effectiveness index are defined by taking into consideration the characteristics of seismic isolated bridges. Limit states for calculation of failure probability are defined on superstructure, isolator and pier, respectively. The results of example design and analysis show that seismic isolation is more cost-effective in low and moderate seismic region than in high seismic region.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.437-452
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• 2012

The Tohoku earthquake (Mw9.0) occurred on March 11, 2011 and caused a large tsunami. The Fukushima Dai-ichi NPP (F1-NPP) were overwhelmed by the tsunami and core damage occurred. This paper describes the overview of F1-NPP accident and the usability of tsunami PRA at Tohoku earthquake. The paper makes reference to the following current issues: influence on seismic hazard of gigantic aftershocks and triggered earthquakes, concepts for evaluating core damage frequency considering common cause failure with correlation coefficient against seismic event at multi units and sites, and concepts of "seismic-tsunami PSA" considering a combination of seismic motion and tsunami effects.

• 한국지진공학회논문집
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• 제26권1호
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• pp.31-38
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• 2022

Based on the nonlinear static analysis and the approximate seismic evaluation method adopted in "Guidelines for seismic performance evaluation for existing buildings, two methods to calculate strength demand for retrofitting individual structural walls in unreinforced masonry buildings are proposed." The displacement coefficient method to determine displacement demand from nonlinear static analysis results is used for the inverse calculation of overall strength demand required to reduce the displacement demand to a target value meeting the performance objective of the unreinforced masonry building to retrofit. A preliminary seismic evaluation method to screen out vulnerable buildings, of which detailed evaluation is necessary, is utilized to calculate overall strength demand without structural analysis based on the difference between the seismic demand and capacity. A system modification factor is introduced to the preliminary seismic evaluation method to reduce the strength demand considering inelastic deformation. The overall strength demand is distributed to the structural walls to retrofit based on the wall stiffness, including the remaining walls or otherwise. Four detached residential houses are modeled and analyzed using the nonlinear static and preliminary evaluation procedures to examine the proposed method.

• Steel and Composite Structures
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• 제14권4호
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• pp.349-365
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• 2013

Structures consisting of concrete and steel parts, which are irregular in damping ratios are investigated. This investigation is a code-based seismic design of such structures. Several practical difficulties encountered, due to inherent differences in the nature of dynamic response of each part, and the different damping ratios of the two parts. These structures are irregular in damping ratios and have complex modes of vibration so that their analysis cannot be handled with the readily available commercial software. Therefore, this work aims to provide simple yet sufficiently accurate constant values of equivalent damping ratios applied to the whole structure for handling the damping irregularity of such structures. The results show that the equivalent damping ratio changes with the height of the building and the kind of the structural system, but it is constant for all accelerations values. Thus, available software SAP2000 applied for seismic analysis, design and the provisions of existing seismic codes. Finally, evaluation of different kinds of structural system used in this research to find the most energy dissipating one found by finding the best value of quality coefficient.

• 한국지진공학회논문집
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• 제21권2호
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• pp.77-85
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• 2017

Pseudo-static approach has been conventionally applied for the design of gravity quay walls. In this method, the decision to select an appropriate seismic coefficient ($k_h$) is an important one, since $k_h$ is a key variable for computing an equivalent pseudo-static inertia force. Nonetheless, there is no unified standard for defining $k_h$. Likewise, port structure designers in Korea have a difficulty in choosing an appropriate $k_h$ definition, as there are conflicts in how $k_h$ is defined between the existing seismic code of port structures and the proposed new one. In this research, various seismic design codes for port structures were analyzed to compare the definitions of the seismic coefficient. The results were used for the proposing a unified seismic coefficient definition. Further, two dynamic centrifuge tests were performed with different wall heights (5 m, 15 m) to clarify the reference point of peak acceleration used in determination of $k_h$ according to the wall height. Results from dynamic centrifuge experiments showed that correction factors for the peak ground acceleration considering both the wall height and allowable displacement are needed to calculate $k_h$.

• 산업기술연구
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• 제26권B호
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• pp.73-81
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• 2006

A sensitivity analysis about effects of influencing factors on the stability of Soil cut slope was performed. Slope stability analyses were carried out under dry, rainy and seismic conditions. Dominant factors controlling the slope stability were chosen such as cohesion and internal friction angle, unit weight of soil, water table and seismic horizontal coefficient used for the slope stability during earthquake. Parametric stability analysis with those factors was performed for sensitivity analysis. As results of analyzing the sensitivity of factors under dry and rainy conditions, effects of cohesion, internal friction angle and unit weight of soil on the stability of slope are more critical in the dry condition than in the rainy condition. Cohesion and internal friction angle are more dominant factors influencing the slope stability irrespective of dry or rainy conditions than unit weight of soil and the horizontal seismic coefficient. The unit weight and the horizontal seismic coefficient affects crucially the stability according to conditions of slope formation and dry or rainy seasons. For the effect of horizontal seismic coefficient on stability of slope, safety factor of slope is not affected significantly by dry or rainy conditions. However, increase of the horizontal seismic coefficient under the rainy condition floes reduce the safety factor significantly rather than the dry condition. Therefore, it is needed that the location of the water table is assigned appropriately to satisfy the required safety factor of stability in the case of checking slope stability for the rainy and seismic conditions.

• 한국전산구조공학회논문집
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• 제33권6호
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• pp.401-409
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• 2020

확률론적 지진취약도 평가는 구조물 혹은 기기의 손상확률을 각 취약도 변수별 조합을 통해 이루어진다. 지진취약도로부터 구해지는 2개 이상 기기의 동시손상확률 계산은 기존에는 각 기기의 손상확률을 독립으로 가정해 왔다. 하지만 기기별 손상확률에 상관성이 있으며, 이를 평가한 결과 상관성에 따라 동시손상확률이 변화할 수 있는 결과를 보였다. 이 지진상관성을 무시하면 비보수적인 결과가 나오고 따라서 이를 고려해서 계산되어야 한다. 이 연구에서는 지진상관계수를 해석적으로 평가하기 위해 몇 가지 확률 변수를 선정하여 각 변수별로 혹은 통합하여 평가하고 그 차이를 비교했다. 그리고 단순화된 모델과, 복잡한 모델에 대한 상관계수 차이도 비교하였다. 이들 방법에 따른 상관계수의 결과와 차이를 분석했다. 그 결과 각 변수별로 평가하는 것과 통합하여 평가할 때 변수별 영향의 차이에 따라 상관성이 변화함을 확인하였고, 모델이 단순할수록 상관성이 높아짐을 확인하였다.

• Structural Engineering and Mechanics
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• 제41권4호
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• pp.479-494
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• 2012

This study explores a coefficient-based seismic capacity assessment method with a special emphasis on low-rise masonry in-filled (MI) reinforced concrete (RC) buildings subjected to earthquake motion. The coefficient-based method without requiring any complicated finite element analysis is a simplified procedure to assess the maximum spectral acceleration capacity of buildings. This paper first compares the fundamental periods of MI RC structures obtained, respectively, from experimental period data and empirical period-height formulas. The coefficient-based method for low-rise masonry buildings is then calibrated by the published experimental results obtained from shaking table tests. The comparison of the experimental and estimated results indicates that the simplified coefficient-based method can provide good approximations of the maximum spectral accelerations at peak loads of the low-rise masonry reinforced concrete buildings if a proper set of drift factors and initial fundamental vibration periods of structures are used.

• 한국구조물진단유지관리공학회 논문집
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• 제22권6호
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• pp.138-147
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• 2018

최근 경주, 포항 등 국내에서 지진으로 인한 피해가 지속적으로 발생하면서, 우리나라가 더 이상 지진의 안전지대가 아니며 이에 대한 대비가 필요함을 알게 되는 계기가 되었다. 또한 내진설계 개념 도입 이전에 건설된 교량들은 적절한 보강 대책이 마련되지 않은 상태로 남아있는 실정으로 경제성과 구조적 안전성이 고려된 내진보강이 순차적으로 이루어져야한다. 기존 교량의 내진성능 예비평가는 교량이 위치한 지역의 지진세기를 고려한 지진도와 취약도 및 영향도를 고려하여 4개의 그룹으로 내진 그룹화하고 이를 통해 내진성능 상세평가를 위한 우선순위가 결정된다. 본 연구에서는 기존의 방법과 다르게 교량의 중요도와 취약조건, 도로교의 세부사항을 기준으로 선정하여 도로교의 내진 보강 우선순위를 결정하는 보다 간편하고 객관적인 알고리즘을 제안하고 이를 실제 교량에 적용하여 적합성을 확인하였다.