• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.268-274
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• 2023

Finite source inversion is performed with a Green's function matrix and geodetic coseismic displacement. Conventionally, the Green's function matrix is constructed using the Okada model (Okada, 1985). However, for more realistic earthquake simulations, recent research has widely adopted the physics-based model, which can consider various material properties such as elasticity, viscoelasticity, and elastoplasticity. We used the physics-based software PyLith, which is suitable for earthquake modeling. However, the PyLith does not provide a mesh generator, which makes it difficult to perform finite source inversions that require numerous subfaults and observation points within the model. Therefore, in this study, we developed CPInterface (COMSOL-PyLith Interface) to improve the convenience of finite source inversion by combining the processes of creating a numerical model including sub-faults and observation points, simulating earthquake modeling, and constructing a Green's function matrix. CPInterface combines the grid generator of COMSOL with PyLith to generate the Green's function matrix automatically. CPInterface controls model and fault information with simple parameters. In addition, elastic subsurface anomalies and GPS observations can be placed flexibly in the model. CPInterface is expected to enhance the accessibility of physics-based finite source inversions by automatically generating the Green's function matrix.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.240-241
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• 2016

본 논문에서는 지난 9월 12일에 한반도 관측 이래 최대 규모 5.8 지진이 발생한 경주 피해현황 대장(엑셀)을 지자체로부터 제공받아 피해현황에 대해 공간분석을 실시하였다. 현황정보를 기반으로 지진피해 주소 데이터를 기반으로 지오코딩을 수행하였으며 약 5,906건(95.6%)에 대한 속성정보를 공간정보화 하였다. 지질도 및 단층정보로 구축한 공간DB를 중첩 분석하여, 시각화된 지진피해 현황 결과를 제시하였다. 마지막으로 지진피해지역의 특징 및 현황 분석이 일차적으로 이루어져야 하며, 향후 지진피해 데이터 및 공간분석을 기반으로 지진 발생시 피해가 예상되는 지역에 대해 예측하는 모델링 및 시스템 고도화를 추진해야 할 것이다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.903-908
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• 1998

KALIMER 원자로 건물에 대하여 3차원 쉘요소 모델과 단순 빔모델을 작성하고 고유진동수 해석을 수행하였다. 두 모델의 1차 수평방향 고유진동수는 대체로 일치하였다. 단순 빔모델에 대해 원자로건물의 회전 관성모멘트를 해석에 반영한 경우 3차원 모델에는 없는 회전모드가 발생되었다. 지진응답해석은 1940 EL Centro와 인공지진에 대하여 수행하였으며, 두 결과는 면진구조물의 경우 비면진구조물과 비교하여 응답가속도가 크게 줄고, 상대변위가 증가하는 경향을 보였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.3 s.22
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• pp.29-35
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• 2006

Fiber element method in earthquake response analysis of bridges is used to represents a realistic flexural deformation according to nonlinear behavior of beam-column section. Nonlinear pseudo-static analysis of two column bent using fiber element is accomplished and failure mechanism of the plastic hinge region is studied. Load-displacement curve obtained by nonlinear pseudo-static analysis can be applicable to earthquake response analysis by capacity spectrum method. The nonlinear time history analysis of a full bridge model using fiber element experienced by the ground motion corresponding to the target response spectrum is accomplished. The result of time history analysis is similar to that of capacity spectrum method.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.241-251
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• 2007

The observed spectra from Odaesan earthquake were fitted to a point-source spectral model to evaluate the source spectrum and spatial features of the modelling error. The source spectrum was calculated by removing from the observed spectra the path and site dependent responses (Yun, 2007) that were previously revealed through an inversion process applied to a large accumulated spectral dataset. The stress drop parameter of one-corner Brune's ${\omega}^2$ source model fitted to the estimated source spectrum was well predicted by the scaling relation between magnitude and stress drop developed by Yun et al. (2006). In particular, the estimated spectrum was quite comparable to the two-corner source model that was empirically developed for recent moderate earthquakes occurring around the Korean Peninsula, which indicates that Odaesan earthquake is one of typical moderate earthquakes representative of Korean Peninsula. Other features of the observed spectra from Odaesan earthquake were also evaluated based on the commonly treated random error between the observed data and the estimated point-source spectral model. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the $Q_0$ map which are indicatives of seismic boundaries.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.2
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• pp.59-68
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• 1997

Seismic responses of the Hualien large scale seismic test model on a layered soil site are estimated for three recorded earthquakes with different level of peak acceleration using two different approaches of soil-structure interaction analysis. The analysis results are then compared and evaluated with the recorded. The method adopted for the analysis is based on substructuring method using a lumped parameter model in both the frequency and time domain. The study results indicate that the proposed method can reasonably estimate the earthquake responses of a soil-structure interaction system of r engineering purposes if the techniques of defining input motion and modeling of the backfilled soil are prudently selected.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.216-216
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• 2021

해저지진, 해저붕괴 및 해저화산분출 등에 발생되는 지진해일은 파장이 수십에서 수백 km에 이르는 장파로서 에너지 손실없이 먼 거리를 전파할 수 있으며, 수심이 상대적으로 얕은 해안가에 도달하면 범람에 의해 인명 및 재산피해를 야기시킬 수 있다. 예를 들어, 2004년 12월 26일에 발생한 수마트라 지진해일은 약 30만명의 인명피해와 약 10조원의 재산피해를 가져왔으며, 2011년 3월 11일에 발생한 동일본 지진해일은 약 2만명의 인명피해와 약 330조의 재산피해를 유발시켰다. 더욱이, 지진해일에 의해 폭발한 후쿠시마 원자력발전소에서의 방사능 유출은 10년이 지난 현재도 생태계 교란, 방사능 피폭 등의 피해를 일으키고 있다. 우리나라도 1983년 5월 26일 발생한 동해 중부지진해일에 의해 삼척시 임원항 및 인근에서 인명피해(1명 사망, 2명 실종)와 약 2억원의 재산피해가 발생하였다. 최근, 4차 산업혁명으로서 빅데이터를 기반으로 한 다양한 인공지능기술이 개발되고 있으며, 많은 분야에서 이 기술을 적용하고자 노력하고 있다. 특히, 과학 및 공학분야에서도 이를 융합하는 연구 및 활용하는 사례가 증가하고 있다. 본 연구에서는 1983년 발생한 중부지진해일에 의해 인명 및 재산피해가 발생한 임원항을 대상으로 지진해일 수치모형실험을 수행하며, 수치모형실험 결과를 토대로 인공지능 모델 중 합성신경망 (Convolution Neural Network)을 활용하여 인공지능을 통한 지진해일 범람구역을 산정 및 평가하고자 한다.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.137-139
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• 2007

To enhance capability on discerning local and regional seismic phases, such as, Pn, Pg, Sn, Rg, etc, within the crust, 2-D numerical forward modeling will be applied to the data obtained from local seismic stations by simulating almost all waves including not only body wave but also surface wave generated without having to explicitly include them under consideration of Q factor. In this study, after getting rid of instrumental response by deconvolution, pseudo-spectral method instead of relying on typical numerical methods, such as, FEM(Finite Element Method) and FDM(Finite Difference Method), will be implemented for 2-D numerical forward modeling by considering velocities of P-wave and S-wave, density, and Q factors. Ultimately, the Power of reaching the enhanced capability on discerning local and regional seismic phases will make it easier for us to identify the seismic source, whether it is originated from man-made explosion or pure earthquake.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.493-505
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• 2013

This numerical study investigates seismicity and fault slip induced by fluid injection in deep geothermal reservoir with pre-existing fractures and fault. Particle Flow Code 2D is used with additionally implemented hydro-mechanical coupled fluid flow algorithm and acoustic emission moment tensor inversion algorithm. The output of the model includes spatio-temporal evolution of induced seismicity (hypocenter locations and magnitudes) and fault deformation (failure and slip) in relation to fluid pressure distribution. The model is applied to a case of fluid injection with constant rates changing in three steps using different fluid characters, i.e. the viscosity, and different injection locations. In fractured reservoir, spatio-temporal distribution of the induced seismicity differs significantly depending on the viscosity of the fracturing fluid. In a fractured reservoir, injection of low viscosity fluid results in larger volume of induced seismicity cloud as the fluid can migrate easily to the reservoir and cause large number and magnitude of induced seismicity in the post-shut-in period. In a faulted reservoir, fault deformation (co-seismic failure and aseismic slip) can occur by a small perturbation of fracturing fluid (<0.1 MPa) can be induced when the injection location is set close to the fault. The presented numerical model technique can practically be used in geothermal industry to predict the induced seismicity pattern and magnitude distribution resulting from hydraulic stimulation of geothermal reservoirs prior to actual injection operation.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.3
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• pp.29-38
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• 2009

n the event of an earthquake, additional stresses can occur in the continuous welded rails (CWR) of High-speed railway (HSR) bridges due to relative displacements at expansion joints, and this stress can cause derailment. The amplification of ground motion occurs as a result of site effects, and this is pronounced at the site of a soft surface soil layer and of a rigid surface soil layer over a soft one. As a result, the amplified ground motion leads to an amplified seismic response in HSR bridges. A change in bridge pier height affects the seismic behavior of the bridge. A HSR bridge with gravel ballast tracks will show different dynamic behavior during an earthquake than one with concrete ballast tracks. The seismic responses of HSR bridges and their CWR are analyzed considering the derailment-inducing factors.