• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.391-398
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• 1998

To understand the current seismic activity and regional tectonic status in and around Gyeongsang basin, Korea Institute of Geology, Mining, and Materials(KIGAM) has performed the earthquake monitoring around the Gyeongsang basin since early 1980's with portable analog seismic instruments for about two months every year. As a part of POSEIDON project, Korea-Japan joint observation around gyeongsang basin in 1991 and 1992, was performed using by temporary seismic station. KIGAM has been continuously operated nine short-period 3-components digital seismic stations since the end of 1994. During the observation period, 247 earthquakes were analyzed and their magnitude was less than 4.5. In general, we could not find any relationship between seismic activity and known surface geological features. But the epicenters were rather concentrated with NW-SE direction. The most active seismicity was found in Gyeongbuk Gyeongjugun Seokeupri and Hyodongri, and Yeongilgun Janggiri and Guryongpo in land, and in three region along the east coast which are 10km and 30km east off from Gampo and 30km east off from Jongja in offshore.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1223-1234
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• 2009

The outlines of seismic PSA implementation standards and seismic hazard evaluation procedure were shown. An overview of the cause investigation of seismic motion amplification on the Niigata-ken Chuetsu-oki (NCO) earthquake was also shown. Then, the contents for improving the seismic hazard evaluation methodology based on the lessons learned from the NCO earthquake were described. (1) It is very important to recognize the effectiveness of a fault model on the detail seismic hazard evaluation for the near seismic source through the cause investigation of the NCO earthquake. (2) In order to perform and proceed with a seismic hazard evaluation, the Japan Nuclear Energy Safety Organization has proposed the framework of the open deliberation rule regarding the treatment of uncertainty which was made so as to be able to utilize a logic tree. (3) The b-value evaluation on the "Stress concentrating zone," which is a high seismic activity around the NCO hypocenter area, should be modified based on the Gutenberg-Richter equation.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.883-888
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• 2001

In Korea, countermeasures against earthquake disasters such as the seismic performance evaluation and/or retrofit scheme of buildings have not been fully performed since Korea had not been experienced many destructive earthquakes in the past. The main objective of this paper is to propose the basic seismic protection index (Es) suitable to Korean buildings based on the seismic evaluation of existing reinforced concrete buildings using modified strength index. This paper will focus on 1) the selection of weak and moderate earthquake waves representing Korean seismic zone, 2) the creation of the required strength ratio spectra by seismic response analysis, and 3) the proposition of the basic seismic protection index (Es) suitable to Korean seismic activity based on required strength ratio spectra

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.23-30
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• 1998

An estimation of seismic risk parameters by seismic zones of the Korea Peninsula in order to calculate the seismic hazard values using these was erformed. Seven seismic source zones were selected in consideration of seismicity and geology of Korean Peninsula. The seismicity parameters that should be estimated are maximum intensity, activity rate and b value in the Gutenberg - Richter relation. For computation of these parameters, least square method or maximum likelihood method is applied to the earthquake data in two ways; the one for the data without maximum intensity and the other with maximum intensity. Earthquake data since Choseon Dynasty is regarded as complete and estimation of parameters was made for these data using above two ways. And recently, a new method is published that estimate the seismicity parameters using mixed data containing large historical events and recent complete observations. Therefore, this method is applied to the whole earthquake data of the Korean Peninsula. It turns out that the b value computed considering maximum intensity is slightly lower than that computed considering without maximum intensity, and it becomes still lower when the incomplete data prior to Choseon Dynasty is used. In the case of the activity rates, the values obtained without maximum intensity and that with maximum intensity are similar, though they are lower when the incomplete data is used. The values of maximum intensities are usually lower when considering incomplete data. In the seismic source zone including the Yangsan Fault zone, however, the values are higher when considering the incomplete data.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.64-71
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• 1999

Seismicity of the Korean Peninsula shows intraplate seismicity that has irregular pattern in both time and space. Seismic data of the Korean peninsula consists of historical earthquakes and instrumental earthquakes. In this study we devide these data into complete part and incomplete part and considering earthquake size uncertainty estimate seismic hazard parameters - activity rate λ, b value of Gutenberg-Richter relation and maximum possible earthquake IMAX by statistical method in each major tectonic provinces. These estimated values are expected to be important input parameters in probabilistic seismic hazard analysis and evaluation of design earthquake.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.573-586
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• 2019

A seismic hazard map based on spatial analysis of various sources of geologic seismic information was developed and assessed for regional seismic vulnerability in South Korea. The indicators for assessment were selected in consideration of the geological characteristics affecting the seismic damage. Probabilistic seismic hazard and fault information were used to be associated with the seismic activity hazard and bedrock depth related with the seismic damage hazard was also included. Each indicator was constructed of spatial information using GIS and geostatistical techniques such as ordinary kriging, line density mapping and simple kriging with local varying means. Three spatial information constructed were integrated by assigning weights according to the research purpose, data resolution and accuracy. In the case of probabilistic seismic hazard and fault line density, since the data uncertainty was relatively high, only the trend was intended to be reflected firstly. Finally, the seismic activity hazard was calculated and then integrated with the bedrock depth distribution as seismic damage hazard indicator. As a result, a seismic hazard map was proposed based on the analysis of three spatial data and the southeast and northwest regions of South Korea were assessed as having high seismic hazard. The results of this study are expected to be used as basic data for constructing seismic risk management systems to minimize earthquake disasters.

• KCI Concrete Journal
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• v.11 no.3
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• pp.191-199
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• 1999

A Precast frame system with hybrid beam-column connections was proposed in this study. An analytical study evaluated the system under seismic loadings. Four buildings with different heights were modeled in which each building had three types of joint details (A. B, C). Thus, twelve buildings were examined with variables such as building height and joint detail. Four earthquake records were applied to the buildings as input ground motions. All the records were normalized to the intensity of 0.25g to assess behavior under the same intensity of seismic excitation. All the joint types showed almost identical results except for the Mexico earthquake which was scaled up from 0. 1g to 0.25g. Buildings with the type C joint exhibited the largest deflection for the Mexico earthquake. It was concluded that type B joint could be used in a high seismic zone and the type C joint could possibly be used in the regions of low to medium seismic activity.

• Earthquakes and Structures
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• v.23 no.3
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• pp.315-328
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• 2022

Structures designed for wind have an opposite design approach to those designed for earthquakes. These structures are usually reliable if they are constructed in an area where there is almost no or less severe earthquake. However, as seismic activity is unpredictable and it can occur anytime and anywhere, the seismic safety of structures designed for wind must be assessed. Moreover, the design approaches of wind and earthquake systems are opposite where wind design considers higher stiffness but earthquake designs demand a more flexible structure. For this reason, a novel Machine learning framework is proposed that is used to assess and classify the seismic safety of the structures designed for wind load. Moreover, suitable criteria is defined for the design of wind resistance structures considering seismic behavior. Furthermore, the structural behavior as a result of dynamic interaction between superstructure and substructure during seismic events is also studied. The proposed framework achieved an accuracy of more than 90% for classification and prediction as well, when applied to new structures and unknown ground motions.

• Ocean and Polar Research
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• v.24 no.3
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• pp.249-253
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• 2002

There is a great deal evidence concerning crustal uplift, after deglaciation, in the vicinity of Syowa Station $(69^{\circ}S,\;39^{\circ}E)$ from tide gauge data, seismic evidence, raised beaches, marine terraces, etc. The geomorphological and tide gauge data show that the crustal uplift is going on around Syowa Station. Seismic observations at Syowa Station started in 1959. Phase readings of the earthquakes have been published by National Institute of Polar Research once a year since 1968, as one of the Data Report Series. Eighteen local earthquakes were detected on short period seismograms at Syowa Station in 1990-2000. The seismicity during the period from 1990 to 2000 was lower than that from 1987 to 1989 when epicenters of local earthquakes were determined by tripartite seismic array. Local earthquake activity corroborates the crustal uplif4 which is an intermittent phenomenon. Sea level falling of 4.5 mm/y was found using data in 1975-1992. This felling rate is consistent with the geomorphological data. A route for repeat leveling survey was established in East Ongul Island. No appreciable change of sea level was observed for the last 14 years. A dynamics of the crustal uplift around Syowa Station has been discussed using geomorphological data, ocean tide, and seismic and leveling data, which is estimated to be an intermittent phenomenon. When local seismic activity is high, the crustal uplift is estimated to be going on. On the contrary, the crustal uplift is in dormancy when the local seismicity is low. Repeated leveling measurements suggest no significant changes, which further supports the idea that the crustal uplift in offshore is not a tilt trend movement but a block movement.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.197-202
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• 2005

The electromagnetic signals associated with the seismic activity in the south-east offshore of Kii peninsula, Japan, were clearly recorded at the MT sites in Jeju island, Korea. In this research, we have identified the co-seismic electromagnetic signals associated with the seismic activity and have analyzed the characteristics of significant electromagnetic variations. The analysis of phase velocity, power spectral density, MT impedance and polarization direction shows that the significant earthquake signals have the frequency band of about 0.05 to 0.5 Hz and that the sources of electromagnetic field are local effects of passing seismic waves. The simple approximation using electrokinetic effect successfully explains the co-seismic EM signals coincides with measured data but cannot explain the localities of electromagnetic variations.