• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.1
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• pp.13-34
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• 2000

본 연구에서는 서기 2년부터 1977년까지 남.북한 역사지진(A.D 2-1904)과 초기 계기 지진(1905-1977) 목록을 이용하여 남한 지진 규모로 재조정된 지진목록을 작성하였다 역사 지진은 과거의 협소한 인구분포로 인해 지진 기록의 누락이 많앗다 지진 위험도를 작성하기 위해 지진 발생분포와 지체구조의 특성을 고려하여 4개의 지진구(seismic province)를 설정하였다. 각 지진구에서 최대 잠재 지진결정은 Gumbel의 최대치 이론을 이용하였다 제 1수정 점근 함수 분포에서 유한 상한 값(finte upper boundary) 의 존재는 각 지진구에서 발생할 최대 잠재 지진의 진원(source)이 유한하다는 사실과 잘 일치한다. 따라서 이를 근거로 각 지진구에서 10년 , 20년, 30년, 50년 이내에 2% 5% 10% 초과 확률을 갖는 최대 규모지진을 추정하였다 또한 각 지진구에서 유한 지진원은 과거에 발생했던 큰 규모의 특정 지진과 지진 지체구조 정보에 근거하여 결정하였다. 연구결과 조선시대(1392-1904) 의 지진위험도에서는 경주 울산지역과 서울과 평양지역을 따라 높은지반 가속도 값을 보이며 경주지역에서 0.24g의 최대 지반 가속도 값으로 나타났다 계기 지진목록(1905-1998)을 이용한 한반도의 지진 위험도에서는 경주, 울산, 대구 지역에서 0.10-0.12g 의 최대 지반가속도 값을 보였다. 그리고 계기 지진 목록(1905-1998) 만을 이용하여 작성한 서울.경기 지역의 지진 위험도에서는 김포, 잠실 , 성남 지역의 한강을 따라 분포하는 충적층과 강남지역의 지반 운동이 한강 이북의 대보 화강암 지역에 비해 비교적 높은 0.09-0.10g의 지반 가속도를 보이는 것이 특징이다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.1-12
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• 2018

This study presents the seismic response characteristics of domestic cable-supported bridges due to 3 earthquakes with magnitudes of 5.1, 5.8, and 4.5 in Richter scale, which occurred around Gyeongju region in 2016. The seismic acceleration response signals, recorded by the seismic acceleration sensors at the free field near bridge and designated positions on bridge, are utilized to characterize the seismic responses of structural elements of cable-supported bridges. The dynamic behaviors of bridges are presented through Fourier transform of acceleration time history. Using the peak accelerations normalized by those at the free fields, amplification effects on the tops of the pylons are analyzed comparatively bridge by bridge. Using aforementioned analyses, the necessity of development on the creteria of alert levels is discussed for the earthquake disaster response of cable-supported bridges.

• Journal of the Korea Society of Computer and Information
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• v.25 no.5
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• pp.73-79
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• 2020

As the number of earthquakes gradually increases on the Korean Peninsula, much research has been actively conducted to detect earthquakes quickly and accurately. Because traditional seismic stations are expensive to install and operate, recent research is currently being conducted to detect earthquakes using low-cost MEMS sensors. In this article, we evaluate how a low-cost MEMS acceleration sensor installed in a smartphone can be used to detect earthquakes. To this end, we installed about 280 smartphones at various locations in Korea to collect acceleration data and then assessed the installed sensors' noise floor through PSD calculation. The noise floor computed from PSD determines the magnitude of the earthquake that the installed MEMS acceleration sensors can detect. For the last few months of real operation, we collected acceleration data from 200 smartphones among 280 installed smartphones and then computed their PSDs. Based on our experiments, the MEMS acceleration sensor installed in the smartphone is capable of observing and detecting earthquakes with a magnitude 3.5 or more occurring within 10km from an epic center. During the last several months of operation, the smartphone acceleration sensor recorded an earthquake of magnitude 3.5 in Miryang on December 30, 2019, and it was confirmed as an earthquake using STA/LTA which is a simple earthquake detection algorithm. The earthquake detection system using MEMS acceleration sensors is expected to be able to detect increasing earthquakes more quickly and accurately.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.392-397
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• 1996

지반특성에 따라 지진발생시 면진구조물과 비면진 구조물의 응답특성이 어떠한가를 평가하기위해, 1940 El Centro 지진을 입력지진으로 하고, 면진구조물로는 가압경수형 원자로격납건물을 이용하여 수평(NS) 및 수직지진입력에 대한 시간이력해석을 수행하였다. 0.5Hz 수평면진 구조물의 경우 수평방향 가속도응답은 지반특성에 무관하게 거의 변화가 없으며, 또 2Hz 이상에서 비면진구조물의 수평지진가속도응답보다 현저히 낮은 가속도응답을 갖는다. 면진베어링의 수직방향 21Hz 고유진동수는 풍화암의 경우 수직방향 가속도응답에 영향을 주지 않으나. 경암의 경우 원자로지지점에서의 수직방향 가속도응답을 전반적으로 증가시킨다. 비면진 구조물의 경우 지반의 강성이 약할수록 가속도응답이 비교적 큰 폴라크레인위치에서 수평 및 수직방향 가속도응답이 감소되는 것으로 나타났으며, 특히 수직방향의 가속도응답이 크게 감소하는 것으로 나타났다.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.1
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• pp.21-28
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• 1999

The objective of the study is to develop attenuation equations of the ground motions in the southern part of the Korean peninsula. The earthquake source characteristics and the medium properties were estimated from available instrumental earthquake records and used as input parameters. The peak ground accelerations(PGA) and pseudo-velocity response spectra(PSV) were simulated by the random vibration theory. The attenuation equations for the PGA and PSV were constructed in terms of local magnitudes and hypocentral distances.

• Journal of the Korean Geotechnical Society
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• v.36 no.10
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• pp.41-56
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• 2020

For the rapid and accurate warning, the system requires not only the sufficient number of seismometers but also the appropriate detection technique of sensor data. Instead of installing new seismometers, on-board accelerometers of the train could be utilized as alternatives. However, the data from on-board accelerometers includes train vibrations and the response of embankment site by earthquake, which are different from earthquakes measured from the seismometer. This study suggests signal analysis technique to detect earthquake from the on-board accelerometer data. The virtual on-board accelerometer data including the response of embankment site, obtained from site response analysis method, has been constructed. The constructed data has been analyzed using short time Fourier transform (STFT) and wavelet transform (WT). STFT method provides better performance to detect long-period earthquake whereas WT method is more available to detect short-period earthquake.

• Explosives and Blasting
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• v.14 no.2
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• pp.71-80
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• 1996

A series of nurmerical analysse for the earhtquake of Iran railway tunnles under construction by NATM(New Astrian Tunnelling Method) were careid out throuth a pseudo-dynamic analyses techique used in a FFM computer program, DWTAP(Daewoo Tunnel Analysis Program), and the results are described in the paper. The analyses were performErl for two case;one is for the primary supports and the other is for the rompletEd permanent roncrete lining. The horizontal and verical groW1d accelerations for the design were estimatEd as 0.34 g and 0.23 g, respectively based on the historical reismic rerords in the proj3et area and the empirical equations. The results show that the turmel would be safe W1der the anticipitOO earthquake motion with the permanent roncrete lining, but some minor cracks rnigt be developErl in the primary shotcrete lining without any significant structural damages.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.161-170
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• 2020

In this study, develop the seismic acceleration measurement data conversion and signal processing algorithms for improve the operational efficiency of the seismic acceleration measurement system installed for public facilities. Through the analysis of the seismic acceleration time history data, the evaluation methods and criteria and evaluating the safety of buildings were proposed. The system was applied to the test bed building to verify its operation and usability. It is expected to be used as a decision making support data and determining the direction and priority of disaster response in the event of an earthquake.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.89-95
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• 2008

Until recently lots of time-history seismic analyses were performed with the earthquake motions recorded at the soft soil surface without taking into account the effects of the soft soil amplification. However, it is important to utilize the bedrock seismic motions for the rational seismic analyses of a structure considering the site soil conditions. In this study, 26 bedrock earthquake records were selected from publicly available 1557 seismic records provided by the Pacific Earthquake Engineering Research Center (PEER) for the study, and the characteristics of them were investigated. Study results showed that it is not reasonable to estimate earthquake acceleration intensity from the magnitude of an earthquake without considering the site soil conditions and it is also hard to draw any general relationships between earthquake acceleration intensity, earthquake magnitude and epicenter distance with bedrock earthquake records in the PEER database. However, 26 bedrock earthquake records selected in this study can be utilized for the time-history seismic analyses of a structure-soil system as bedrock earthquake ones, and it is also confirmed that it is necessary to take into account acceleration intensity, magnitude, epicenter distance and site conditions simultaneously for the proper use of those selected earthquake records.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.51-63
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• 2020

In this study, the model test of a reservoir was performed through a dynamic analysis method by using the data obtained from seismometers. Besides, we analyzed the behavior of the seismic acceleration amplification by reservoir height. To test the model, the data measured by the seismometers were applied at the foundation of the reservoir as input data, and the results from the analysis were compared with the data measured at the dam crest. The analysis results manifest that the peak values and the trend of the seismic wave obtained from the numerical analysis are in good agreement with the measured data. Also, the acceleration amplification ratio was proportional to the reservoir height and the magnitude of the earthquake. Through this study, the dynamic analysis method, which is based on the cyclic elastoplastic constitutive equation, can be considered as an appropriate technique to analyse the seismic behavior by the application of the data obtained from the seismometers installed in the reservoir. Also, the applicability of the seismometers can be enhanced through this technique in the future.