• Geophysics and Geophysical Exploration
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• v.13 no.3
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• pp.219-226
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• 2010

Current earthquake alert notification for immediate post-earthquake procedures for the critical facilities is exclusively dependent on the ground-motion intensity measures observed at the seismic station located within the site. This practice is prune to false notification due to a noise and problems of missing and poor quality records of the seismic station. The credibility of the earthquake alert notification can be enhanced by utilizing the multiple transformed records of the nearby seismic stations at other sites interconnected to the same earthquake monitoring system by a network. The time-domain transformation of the site-response between the seismic stations is implemented by convoluting the nearby records with a pair of forward and inverse FIR filters designed for the site response relative to a seismic basement. The transformed records from the nearby seismic stations can be used to estimate the ground-motion intensity measures missing at the site or to evaluate the data quality along with other various possible applications in the area of geoscience and earthquake engineering.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.253-256
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• 2008

지하 토사 조건 및 지질 구조는 지진 시 지반 운동의 증폭에 관련된 부지 효과에 매우 큰 영향을 미친다. 본 연구에서는 국내 홍성 지역을 대상으로 시추 조사와 현장 탄성파 시험을 포함한 현장 조사 및 지표 부근지질 정보를 획득하기 위한 부지 답사를 통해 부지 효과를 확인하였다. 홍성 지역은 1978년 계기 지진이 발생한 지역으로서 기반암 상부에 최대 약 50 m 두께의 풍화대 지층이 분포한다. 연구 대상 지역의 공간 지층 구조를 효율적으로 확인하기 위하여 지리정보시스템(GIS) 기법 기반의 지반 정보 시스템(GTIS)의 구축하였으며, 홍성 지역은 분지는 얕고 넓은 형상임을 확인하였다. 홍성 지역의 부지 지진 응답을 평가하기 위하여 대표 단면에 대한 2차원 유한 요소 해석을 수행하였다. 도출된 지진 응답으로부터 지반 운동이 기반암 상부 토사층을 통해 전단파가 전파되면서 증폭되고 분지 형상에 따른 전단파의 상호 작용으로 생성된 표면파로 인해 분지 경계 부근 진동 지속 시간이 증가됨을 확인하였다. 뿐만 아니라, 분지 내의 선정된 토사 부지들에 대해서 추가적인 1차원 유한 요소 지진 응답 해석을 수행하였으며, 본 연구 대상 분지가 매우 얕고 넓음에 따라 분지 경계 부근을 제외하고는 분지 내 대부분의 위치에서 2차원 지진 응답과 유사한 결과를 보였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.2
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• pp.37-46
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• 2000

본 논문에서는 부지특성을 고려한 설계지반운동의 산정방법을 연구하였으며 그 해석결과를 지반 구조물의 내진설계에 적용하는 방법을 제안하였다 지진응답 해석시 사용되는 설계응답스펙트럼과 설계시간 이력등의 입력운동의 통제점 위치가 지반구조물 내진설동 지층내 암반운동 그리고 노두운동을 사용하는 방법으로 나눌 수 있고 이에 따라 작용 설계지진운동이 변화하므로 지반구조물의 경계조건에 적합한 방법을 사용하여야 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3C
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• pp.187-196
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• 2008

An earthquake of magnitude 5.0 occurred at Ssang-gye-sa, a Buddhist temple in Jirisan, located near the southern border of the Korean peninsula on 4 July 1936. It resulted in severe damage of several buildings and structures in Ssang-gye-sa. Particularly, the top component of a five-story stone pagoda in the temple was tipped over and fell down during the earthquake. This earthquake damage case would be usefully applied to estimating the intensity of ground motion in the Korean peninsula, a moderate seismicity region, where strong motion has never been recorded with the exception of historic seismic events. In order to estimate the local site effects and the corresponding ground motion at Ssang-gye-sa site, intensive site investigations including borehole drilling and in-situ seismic tests such as crosshole and SASW tests were performed in the temple area. Based on the site characteristics, site-specific seismic response analyses using various input motions were conducted for a representative Ssang-gye-sa site by means of both one-dimensional equivalent-linear and nonlinear methods with six input rock outcrop acceleration levels ranging from 0.044g to 0.220g. The resultant site-specific seismic responses indicated the amplified ground motions in the short-period range near the site period of Ssang-gye-sa. Furthermore, the intensity on rock outcrop of the 1936 Jirisan earthquake was estimated by making a comparison between the site responses analysis results in this study and the full-scaled seismic test of pagoda model in the prior study.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.38-50
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• 2008

The site-specific seismic responses and corresponding seismic hazards are influenced mainly by the subsurface geologic and geotechnical dynamic characteristics. To estimate reliably the seismic responses in this study, a geotechnical information system (GTIS) within GIS framework was developed by introducing new concepts, which consist of the extended area containing the study area and the additional site visit for acquiring surface geo-knowledge data. The GIS-based GTIS was built for Gyeongju area, which has records of abundant historical seismic hazards reflecting the high potential of future earthquakes. At the study area, Gyeongju, intensive site investigations and pre-existing geotechnical data collections were performed and the site visits were additionally carried out for assessing geotechnical characteristics and shear wave velocity ($V_S$) representing dynamic property. Within the GTIS for Gyeongju area, the spatially distributed geotechnical layers and $V_S$ in the entire study area were reliably predicted from the site investigation data using the geostatistical kriging method. Based on the spatial geotechnical layers and $V_S$ predicted within the GTIS, a seismic zoning map on site period ($T_G$) from which the site-specific seismic responses according to the site effects can be estimated was created across the study area of Gyeongju. The spatial $T_G$ map at Gyeongju indicated seismic vulnerability of two- to five-storied buildings. In this study, the seismic zonation based on $T_G$ within the GIS-based GTIS was presented as regional efficient strategy for seismic hazard prediction and mitigation.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.1-13
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• 2007

In order to evaluate the local site effects at two town fortress areas in Korea where stone parapets were col-lapsed by historical earthquakes, site characteristics were assessed using site investigations such as borehole drillings and seismic tests. Equivalent-linear site response analyses were conducted based on the shear ways velocity ($V_s$) profiles and geotechnical characteristics determined from site investigations. The study sites are categorized as site classes C and B according to the mean $V_s$ to 30 m ranging from 500 to 850 m/s, and their site periods are distributed in the short period range of 0.06 to 0.16 sec, which contains the natural period of fortress wall and stone parapet. From the results of site response analyses in the study areas, for site class C indicating most of site conditions, contrary to site class B, the short-period (0.1-0.5 sec) and mid-period (0.4-2.0 sec) site coefficients, $F_a$ and $F_v$ specified in the Korean seismic design guide, underestimate the ground motion in short-period band and overestimate the ground motion in mid-period band, respectively, due to the high amplification in short period range, which represent the site-specific seismic response characteristics. These site-specific response characteristics indicate the potential of resonance in fortress walls during earthquake and furthermore could strongly affect the collapse of parapets resulted from seismic events in historical records.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.1-10
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• 1999

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential for the seismic design to perform the site specific ground response analysis. In this paper, the procedures of site specific ground response analysis were suggested based on the Korean seismic guideline and the review of state of the art technologies. The concept of ground response analysis was introduced, and the techniques of obtaining soil data for one dimensional equivalent linear analysis which include site investigation planning, field and laboratory testing techniques, deformational characteristics of soils at small to large strains, and site characterization techniques combining field and laboratory test results, were suggested. Finally, the case study was performed at Inchon area following the suggested procedure.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.4
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• pp.17-35
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• 2016

Earthquake-induced disasters are often more severe in locations with soft soils than firm soils or rocks due to differences in ground motion amplification. On a regional scale, such differences can be estimated by spatially predicting subsurface soil thickness over the entire target area. In general, soil deposits are generally deeper in coastal or riverside areas than in inland regions. In this study, a coastal metropolitan area, Incheon, was selected to assess site effects and provide information on seismic hazards. Spatial prediction of geotechnical layers was performed for the entire study area within the GIS framework. Approximately 7,000 existing borehole drilling data in the Incheon area were gathered and archived into the GIS Database (DB). In addition, surface geotechnical data were acquired from a walkover survey. Based on the built geotechnical DB, spatial zoning maps of site-specific seismic response parameters were created and presented for use in a regional seismic strategy. Site response parameters were performed to determine site coefficients for seismic design over the entire target area and compared with each other. Site classifications and subsequent seismic zoning were assigned based on site coefficients. From this seismic zonation case study in Incheon, we verified that geotechnical GIS-DB can create spatial zoning maps of site-specific seismic response parameters that are useful for seismic hazard mitigation particularly in coastal metropolitan areas.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.1
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• pp.57-63
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• 2011

In this study, a ground motion response spectrum for the seismic risk assessment of low and intermediate level radioactive waste repositories was developed. For the development of the ground motion response spectrum, a probabilistic seismic hazard analysis (PSHA) was performed. Through the performance of a PSHA, a seismic hazard curve which was based on a seismic bed rock was developed. A uniform hazard spectrum was determined by using a developed seismic hazard curve. Artificial seismic motions were developed based on the uniform hazard spectrum. A seismic response analysis was performed on the developed artificial seismic motion. Finally, an evaluation response spectrum for the seismic risk assessment analysis of low and intermediate level radioactive waste repositories was developed.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.15-23
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• 2009

The site effects relating to the amplification of ground motion under earthquake loading are strongly influenced by both the subsurface soil condition and geologic structure. In this study, the site effects at the Hongseong area in Korea were examined by both the site investigation including borehole drilling and in-situ seismic tests and the site visit for acquiring geologic information of ground surface. Subsurface of Hongseong area with a major instrumental earthquake event in 1978 is composed of weathered layers of a maximum of 45 m thickness overlying bedrock. A geotechnical information system based on GIS framework was implemented to effectively find out spatial geologic structure of study area and it indicated Hongseong is a shallow and wide shaped basin. Two-dimensional finite element (FE) analyses for a representative cross-section of the Hongseong area were performed to evaluate seismic site responses. From the results of seismic responses, it was observed that the ground motions were amplified during the propagation of shear waves through the soil layer overlying the bedrock and the duration of shaking near the basin edges was prolonged due to the surface waves generated by interactions of shear waves with basin geometry. Furthermore, one-dimensional FE seismic response analyses were additionally conducted for soil sites selected in the basin, and it gives similar results to the two-dimensional seismic responses at most locations in the basin with the exception of the locations near the basin edges, because the basin in this study is very shallow and wide.