• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.35-42
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• 2010

The best estimate Gutenberg-Richter b-value of the Korean Peninsula was estimated through an expert panel assigned to evaluate the currently available study results. The panel's assessment yielded that the Gutenberg-Richter b-value was relatively constant over the Korean Peninsula and was independent of seismic zones with an average value of 0.96. Also, the currently most reliable four seismotechtonic structural maps were produced. The effects on the seismic hazard were analyzed by applying the results to the Shinwuljin Units 1&2 NPP site. As a result, the mean hazard level at 0.2g was decreased by about 70-80% (on the order of 0.6-0.7), and the uncertainty band at 0.2g for the reliability band of 15%-85% was significantly reduced. It was proposed, for conservatism, to use b=0.95 over all seismic zones for seismic hazard analysis in the future.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.104-113
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• 2006

The main objective of this study is to investigate the effect of compounded welding by using acoustic emission (AE) signals and doing a source location for weld heat affected zone (HAZ) through tensile testing. This study was carried out an SWS 490A high strength steel for electric shield metal arc welding, SMAW; $CO_2$ gas metal arc welding, GMAW($CO_2$); and gas tungsten arc welding, GTAW/TIG. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. For instance, Gutenberg-Richter magnitude-frequency relationship (G-R MFR) offers useful b-value in data analysis. Namely event identification, source location gives the X- and Y-coordinates of the AE source. And K-means clustering analysis by Euclidean distance confirmed that was powerful to source location. Generally, strength of welded metal zone was stronger than strength of base metal. As the result, confirmed certainly that fracture is produced in HAZ instead of welded metal zone from source location.

• 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.

• The Journal of Engineering Geology
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• v.8 no.2
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• pp.99-114
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• 1998

The Yangsan fault system of Kyungsang Basin in the southeastern part of Korean peninsula is one of the most important structures in the peninsula. A number of strong earthquakes occurred in the vicinity of the fault. It was suggested that this fault can be divided into three segments: northern, central and southern ones. Earthquake data around the Yangsan fault were classified into two groups as incomplete and complete ones; the former is the data before the Choseon Dynasty and the latter is those since the dynasty. The maximum likelihood method was applied to compute seismicity parameters such as earthquake occurrence rates, b-values of frequency-magnitude relation and maximum possible magnitudes for each segment and the entire fault. These parameters show considerably different values from segment to segment. The b-value for the entire fault turned out to be 0.85 and maximum possible magnitudes for the northern, central and southern segments are 5.2, 6.8 and 6.0, respectively. The mean return periods for the maximum possible magnitudes for each segments are greater than 1000 years. In addition, according to the analysis of the frequency-magnitude relation, the occurrence pattern of earthquakes around the Yangsan fault show more similarity to the characteristic earthquake model than the Gutenberg-Richter model. The data for each segments are, however, too scarce to obtain any physically meaningful results.

• 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 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.