• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.57-61
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• 2001

This study introduces an algorithm for determination of hypocentral parameters using phase analysis and two-point ray tracing to enhance accuracy and stability of computations. When the magnitude of earthquake is relatively small(usually $m_{b}$<3.2), the PmP phase which looks like the first arrival phase may be observed without observing the Pn phase. In this case, the hypocentral parameters calculated by the existing method using the first arrival of P and S phases and by the method developed in this study using PmP and SmS phases show large differences. The computational results of determination of hypocentral parameters for actual earthquake events show that this method gives much smaller rms errors than the existing methods do.o.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.57-65
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• 2000

파형분석과 두 점을 잇는 파선추적은 진원요소 결정의 정확성을 향상시키는 주요한 요인이다. 본 연구에서는 3성분 지진기록의 직선형도(rectilinearity) 함수와 방향성(directionality)함수를 사용하여 파형분석한 결과와 두 점을 잇는 파선추적을 기존의 진원요소결정 프로그램에 적용하여 진원요소 결정의 정확성을 증가시켰다. 지진의 규모가 작을 때 Pn이 보이지 않고 PmP가 초동파로 기록된 것처럼 보인다. 이러한 지진에서는 주어진 진앙거리에서 최소 주행시간이 걸리는 P파와 S파의 초동파만 사용한 기존의 진원요소 결정 방법과 본 연구에서 PmP와 SmS를 사용한 결과는 매우 큰 차이를 보인다.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.113-118
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• 1998

1994년 7월 25일 발생한 황해남부 지진(Mb=5.5)의 지진원 요소들을 결정하였다. 지진원 요소들을 결정하기 위하여 이 지진에 대하여 이전의 연구에서 얻어진 지진발생기구를 사용하였다. 지진발생기구에 의하면, 이 지진은 거의 동서방향의 압축응력장에 주향이동성분이 가미되어 발생한 것을 암시한다. 지진원 요소들은 단주기 및 장주기 P파에 대한 원지장 스펙트럼으로부터 계산되었다. 지진모멘트(M0), 코너주파수(f0), 지진원 반경(r) 및 응력강하량($\Delta$$\sigma$)은 각각 M0 = 3.18$\times$1024 dyne-cm, f0=0.3 Hz, r=3.7km, $\Delta$$\sigma$=27bar로 구해졌다. 지진모멘트로부터 산정한 모멘트 규모는 5.6으로 나타났다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.27-31
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• 1999

진도의 거리에 따른 감쇠양상은 두가치 측면에서 중요하다. 첫째는 역사지진의 크기를 평가하는데 사용되고 둘째는 역사지진자료를 이용하여 지진위험도를 평가하는데 이용된다. 한반도의 경우 대부분의 지진활동 자료가 역사지진이므로 이지진들의 크기를 결정하고 이들을 이용하여 지진위험도를 평가하기 위하여 합리적인 진도감쇠양상의 결정은 매우 중요한 과제라 할수 있다 진도의 감쇠양상은 진앙진도와 진앙거리 등 두요소에 같이 의존함이 알려져 있으므로 한반도에서 MMI VIII만의 지진자료를 이용하여 결정된 Lee의 기존의 감쇠공식은 그 사용범위에 한계가 불가피하므로 상기 두 가지 요소를 함께 고려한 새로운 감쇠공식의 유도가 요구되어진다. 지체구조적으로 Sino-Korean 지괴라고 불리우는 중국 북동부와 한반도에서 발생한 MMI VIII-X 지진들의 자료를 이용하여 한반도에서 발생하는 MMI VIII-X의 강진들에 대한 새로운 진도감쇠양상을 결정하였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.5
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• pp.37-46
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• 2007

This is the second of two companion papers that describe non-prismatic beam element for nonlinear seismic analysis of steel moment frames. Described in a companion paper is the formulation of a non-prismatic beam element to model the elastic and inelastic behavior of steel beams, which have reduced beam sections(RBS). This study describes the determination of yield surfaces, stiffness parameters, and hardening (or softening) rule parameters for RBS beam element. Analytical results of the RBS beam element show good correlation with test data and Finite Element Method(FEM) results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.8-14
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• 2017

Nonstructural components, such as electrical equipment, have critical roles in the proper functionality of various infrastructure systems. Some of these devices in certain facilities should operate even under strong seismic shaking. However, it is challenging to define each mechanical and operational failure and determine system failure probabilities under seismic shaking due to the uncertainties in earthquake excitations and the diversity of electrical equipment, among other factors. Therefore, it is necessary to develop effective and practical probabilistic models for performance assessment of electrical equipment considering variations in equipment features and earthquakes. This study will enhance the understanding of the effect of rocking behavior on nonstructural equipment, and linear-to-nonlinear behavior of restrainers. In addition, this study will generate probabilistic seismic demand models of rigid equipment for a set of conventional and novel intensity measures.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.5
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• pp.19-24
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• 2003

We analysed seismic phases recorded by the 10 December 2002 Cheolwon, Korea, earthquake of $M_{L}$ 3.6 and obtained source parameters such as hypocenter, origin time, earthquake magnitude. Velocity and acceleration records used in this study are from the KMA and KIGAM seismic networks. Due to the location of the epicenter in the north of the DMZ(Demilitarized Zone), direct Pg phases were recorded only at five stations in the area south of DMZ. Identification of refracted Pn phase as the first arrival is difficult in most stations. Therefore, the hypocenter determined by existing routine methods could be affected by a large error. In order to avoid the possibility of the problem, we employed a method of seismic phase analysis developed by Kim et al.. The direct, refracted, and reflected P and S phases were successfully identified using the method together with the travel time curve data. In order to improve the accuracy in determination of the hypocenter and origin time, we included PmP and SmS phases in the analysis in addition to the phases such as Pg, Pn, Sg and Sn. The epicenter, depth, and origin time of the Cheolwon earthquake determined based on data of 11 stations within 200km from the epicenter are $38.81^{\circ}$N, $127.22^{\circ}$E, 12.0km, and 7:42:51.4(local time), respectively. The average value of the local magnitude based on the Richter's definition from all the stations is 3.6 in $M_{L}$. This magnitude is smaller by 0.2 and 0.5 compared with magnitudes determined by KMA and KIGAM, respectively.

• Geophysics and Geophysical Exploration
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• v.19 no.2
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• pp.97-104
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• 2016

Small to large earthquakes have been reported in Gyeongju and its vicinity in southeast Korea during historical period as well as instrumental observation period. We identified and located more than 300 earthquakes that occurred between January 2010 and December 2014 in a $20km{\times}30km$ area, but were unreported because of their small magnitudes. We used the Joint Hypocenter Determination (JHD) method to minimize the influence of the differences between the actual earth structure and 1-D velocity model for earthquake locations. The potential relationship between the previously reported Quaternary faults and the earthquake hypocenters was investigated. Many micro-earthquakes were found to be located in the southern segment of the Yeonil Tectonic Line, the Seokup fault, and the Waup basin boundary faults.

• Journal of the Korean Geosynthetics Society
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• v.8 no.1
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• pp.1-10
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• 2009

Earthquake induced landslides have caused tens of thousands of deaths and billions of dollars of damage during the last century alone. Determining the potential seismic hazard presented by statically stable slopes is essential for the evaluation of substantial landslide movement during an earthquake. Newmark's method for estimating landslide displacement under dynamic loading was presented and applied to two case studies. A simplified energy-based method was then be developed to estimate the Newmark's displacement.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.239-249
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• 2005

It is the general consensus that korea is safe from some disasters, particularly earthquake. However, it is not difficult to see the countries considered as safety zones have occasionally experienced a severe earthquakes. In this case, damages and casualties are much serious because they were not prepared for the earthquakes. Therefore, it is necessary to establish a counterplan about an earthquake. In this paper, we analyzed several damages by earthquakes using GIS based methods, and derived a counterproposal. The disasters caused by earthquakes are categorized into three riskiness factors, that is, a building destruction riskiness, a blaze riskiness and a refuge riskiness. Then, it is quantitatively analyzed by the degree of damage so that overall riskiness of the earthquake are assigned. In addition, it was shown that the analysis can be utilized to establish the escape route from the earthquake. It is expected that this study shows an good example of GIS application especially for preventing disasters.