• 한국지반공학회논문집
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• 제36권4호
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• pp.17-30
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• 2020

본 연구의 목적은 2017년 포항지진 시 액상화가 관측되었거나 액상화 가능성이 높은 부지 5곳에 대하여, 국내에서 통상적으로 적용해 왔던 액상화 평가 기준과 최근 개정된 평가 기준을 적용하여 액상화 평가를 실시하고, 이러한 이론적인 액상화 평가 결과와 대상 부지에서의 실제 액상화 발현여부를 비교·검토함으로써, 개정된 액상화 평가 기준의 타당성을 검토하는 데에 있다. 액상화 평가를 위한 해석지진은 기존 국내에서 통상적으로 사용해 온 지진파와 포항 실지진파를 사용하였고, 해석지진의 최대지반가속도 크기는 0.097g~0.2713g 범위의 값을 적용하였다. 해석결과로부터, 기존 국내에서 통상적으로 적용해 왔던 구조물기초설계기준(2016)에 제시된 액상화 평가 기준의 개선점을 제시하고, 2018년에 개정된 내진설계일반에 제시된 액상화평가 기준의 기존 기준대비 개정 사항의 상대적 타당성을 평가해 보았다.

• 한국지진공학회논문집
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• 제12권3호
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• pp.37-44
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• 2008

본 연구에서는 확률적 지진취약도 분석방법을 3경간 FCM 교량에 적용하여 지반특성에 따른 지진취약 교각의 위치와 교각 상 하부에서의 소성힌지 발생 상태를 수치예제 결과의 분석을 통해 평가하였다. 이를 위해, 취약도 곡선을 최대지반가속도(PGA)의 변수에 대한 대수정규분포 함수로 가정하고 대수정규분포 함수의 주요 계수인 중앙값과 대수표준편차는 최우도추정법(Maximum Likelihood Method)으로 구하였다. 또한 지점별 상이한 지반특성은 "도로교표준시방서"에 제시되어 있는 지반의 등가 스프링을 사용하여 해석모델에 반영하였으며, 지진취약도 분석에 필요한 구조물의 손상지수로 교각의 소성힌지에서의 회전연성도를 이용하였다.

• 한국가스학회지
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• 제6권1호
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• pp.46-51
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• 2002

지하철 공사나 도로 공사에서는 다양한 건설장비의 사용으로 인해 발생되는 진동이 가스관에 직$\cdot$간접적으로 영향을 미치고 있다. 특히, 매설가스관은 매설된 위치와 근접한 곳에서 시행되는 발파로 인한 진동영향이 큰 상태이다. 매설가스관 근처의 발파작업시 발생되는 진동에 대한 응답을 해석하기 위해서 등가선형해석법을 적용하여 지반의 비선형거동을 구현하였다. 해석 결과, 매설가스관에서의 가속도 응답치는 실측치와 근사한 결과를 보였고, Peak치 발생시간도 실측치와 거의 일치하였다. 그러므로 매설가스관의 동적해석을 할 때 일반적인 지진해석 메카니즘의 적용이 가능함을 알 수 있었다.

• Steel and Composite Structures
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• 제31권6호
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• pp.629-640
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• 2019

The investigation of retaining wall structures behavior under dynamic loads is considered as one of important parts for designing such structures. Generally, the performance of these structures is under the influence of the environment conditions and their geometry. The aim of this research is to design retaining wall structures based on smart and optimal systems. The use of accuracy and speed to assess the structures under different conditions is one of the important parts sought by designers. Therefore, optimal and smart systems are able to have better addressing these problems. Using numerical and coding methods, this research investigates the retaining wall structure design under different dynamic conditions. More than 9500 models were constructed and considered for modelling design. These designs include height and thickness of the wall, soil density, rock density, soil friction angle, and peak ground acceleration (PGA) variables. Accordingly, a neural network system was developed to establish an appropriate relationship between data to obtain safety factor (SF) of retaining walls under different seismic conditions. Different parameters were analyzed and the effect of each parameter was assessed separately. According to these analyses, the structure optimization was performed to increase the SF values. The optimal and smart design showed that under different PGA conditions, the structure performance can be appropriately improved while utilization of the initial (or basic) parameters leads to the structure failure. Therefore, by increasing accuracy and speed, smart methods could improve the retaining structure performance in controlling the wall failure. The intelligent design process of this study can be applied to some other civil engineering applications such as slope stability.

• 한국지진공학회논문집
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• 제23권2호
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• pp.89-99
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• 2019

In order to increase the seismic safety of nuclear power plant (NPP) structures, a technique to reduce the seismic load transmitted to the NPP structure by using a seismic isolation device such as a lead-rubber bearing has recently been actively researched. In seismic design of NPP structures, three directional (two horizontal and one vertical directions) artificial synthetic earthquakes (G0 group) corresponding to the standard design spectrum are generally used. In this study, seismic analysis was performed by using three directional artificial synthetic earthquakes (M0 group) corresponding to the maximum-minimum spectrum reflecting uncertainty of incident direction of earthquake load. The design basis earthquake (DBE) and the beyond design basis earthquakes (BDBEs are equal to 150%, 167%, and 200% DBE) of G0 and M0 earthquake groups were respectively generated for 30 sets and used for the seismic analysis. The purpose of this study is to compare seismic responses and seismic fragility curves of seismically isolated NPP structures subjected to DBE and BDBE. From the seismic fragility curves, the probability of failure of the seismic isolation system when the peak ground acceleration (PGA) is 0.5 g is about 5% for the M0 earthquake group and about 3% for the G0 earthquake group.

• 한국컴퓨터정보학회논문지
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• 제26권5호
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• pp.95-101
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• 2021

본 연구는 지진의 영향을 등치선의 형태로 표현할 수 있는 Shake을 활용하여 현행 지진재난 정보제공 서비스를 개선하는 방법에 관한 것이다. 미국 지질조사국이 제공하고 있는 ShakeMap 소프트웨어를 사용하여 자동화된 신속 ShakeMap 생성 시스템을 구현하였으며 이를 바탕으로 지진발생 후 사용자의 위치를 기준으로 지진의 위험도를 진도나 지반최대가속도의 형태로 파악할 수 있는 지진재난 정보서비스 개선모델을 제시하였다. 개선된 모델의 구현 가능성과 효과를 검증하기 위하여 경북 포항지역을 대상으로 지진재난 정보서비스앱을 개발하여 시범적으로 운영한 결과 신속 ShakeMap을 활용한 정보제공을 통해 보다 상세한 지진위험도 정보를 제공함으로써 사용자의 안전행동을 보다 효과적으로 유도할 수 있음을 확인할 수 있었다.

• Earthquakes and Structures
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• 제20권3호
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• pp.325-335
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• 2021

The majority of Turkey's geography is at risk of earthquakes. Within the borders of Turkey, including the two major active faults contain the North-Eastern and Eastern Anatolia, earthquake, threatening the safety of life and property. On January 24, 2020, an earthquake of magnitude 6.8 occurred at 8:55 p.m. local time. According to the data obtained from the stations in the region, peak ground acceleration in the east-west direction was measured as 0.292 g from the 2308 coded station in Sivrice. It is thought that the earthquake with a magnitude of Mw 6.8 was developed on the Sivrice-Puturge segment of the Eastern Anatolian Fault, which is a left lateral strike slip fault, and the tear developed in an area of 50-55 km. Aftershocks ranging from 0.8 to 5.1 Mw occurred following the main shock on the Eastern Anatolian Fault. The earthquake caused severe structural damages in Elazığ and neighboring provinces. As a result of the field investigations carried out in this study, significant damage levels were observed in the buildings since it did not meet the criteria in the earthquake codes. Within the study's scope, the structural damage cases in reinforced concrete and masonry structures were investigated. Many structural deficiencies and mistakes such as non-ductile details, poor concrete quality, short columns, strong beams-weak columns mechanism, large and heavy overhangs, masonry building damages and inadequate reinforcement arrangements were observed. Requirements of seismic codes are discussed and compared with observed earthquake damage.

• Advances in nano research
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• 제13권3호
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• pp.285-295
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• 2022

Creation of plastic deformation under seismic loads, is one of the most serious subjects in RC structures with steel bars which reduces the life threatening risks and increases dissipation of energy. Shape memory alloy (SMA) is one of the best choice for the relocating plastic hinges. In a challenge to study the seismic response of concrete moment resisting frame (MRF), this article investigates numerically a new type of concrete frames with nano fiber reinforced polymer (NFRP) and shape memory alloy (SMA) hinges, simultaneously. The NFRP layer is containing carbon nanofibers with agglomeration based on Mori-Tanaka model. The tangential shear deformation (TASDT) is applied for modelling of the structure and the continuity boundary conditions are used for coupling of the motion equations. In SMA connections between beam and columns, since there is phase transformation, hence, the motion equations of the structure are coupled with kinetic equations of phase transformation. The Hernandez-Lagoudas theory is applied for demonstrating of pseudoelastic characteristics of SMA. The corresponding motion equations are solved by differential cubature (DC) and Newmark methods in order to obtain the peak ground acceleration (PGA) and residual drift ratio for MRF-2%. The main impact of this paper is to present the influences of the volume percent and agglomeration of nanofibers, thickness and length of the concrete frame, SMA material and NFRP layer on the PGA and drift ratio. The numerical results revealed that the with increasing the volume percent of nanofibers, the PGA is enhanced and the residual drift ratio is reduced. It is also worth to mention that PGA of concrete frame with NFRP layer containing 2% nanofibers is approximately equal to the concrete frame with steel bars.

• 한국터널지하공간학회 논문집
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• 제24권1호
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• pp.1-13
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• 2022

본 연구에서는 기존에 개발된 개착식 철도 터널의 지진취약도 모델들을 가중 조합하여 새로운 모델을 제시하고 제시한 모델의 적정성을 평가하였다. 지진취약도 함수의 형태는 최대지반가속도의 대수정규분포형태로, 누적확률분포로 표현된다. 독립적으로 개발된 각 모델을 선형 가중 조합하는 것으로 모델의 불확실성을 줄일 수 있기에 4개의 모델에 대하여 25%씩 동등하게 선형가중을 부여하였다. 조합된 지진취약도 곡선에 최대 지반가속도에 대한 피해발생확률을 이용하여 지진취약도 곡선의 중앙값과 표준편차를 결정하여 새로운 지진취약도 함수를 개발하였다. 개발된 지진취약도 함수의 적합성을 평가하기 위하여 다양한 터널의 지진취약도 곡선과 비교 분석을 진행하였다. 개발된 곡선은 상대적으로 지진피해에 안전한 굴착식 터널의 지진취약도 함수와 비슷한 취약도를 갖는 것으로 나타나는데, 대상 터널은 국내 고속철도 개착식 터널로 높은 내진설계 기준에 의해 기인하는 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2387-2395
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• 2021

Seismic qualifications of electrical equipment, such as cabinet systems, have been emerging as the key area of nuclear power plants in Korea since the 2016 Gyeongju earthquake, including the high-frequency domain. In addition, electrical equipment was sensitive to the high-frequency ground motions during the past earthquake. Therefore, this paper presents the rocking behavior of the electrical cabinet system subjected to Reg. 1.60 and UHS. The high fidelity finite element (FE) model of the cabinet related to the shaking table test data was developed. In particular, the first two global modes of the cabinet from the experimental test were 16 Hz and 24 Hz, respectively. In addition, 30.05 Hz and 37.5 Hz were determined to be the first two local modes in the cabinet. The high fidelity FE model of the cabinet using the ABAQUS platform was extremely reconciled with shaking table tests. As a result, the dynamic properties of the cabinet were sensitive to electrical instruments, such as relays and switchboards, during the shaking table test. In addition, the amplification with respect to the vibration transfer function of the cabinet was observed on the third floor in the cabinet due to localized impact corresponding to the rocking phenomenon of the cabinet under Reg.1.60 and UHS. Overall, the rocking of the cabinet system can be caused by the low-frequency oscillations and higher peak horizontal acceleration.