• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.81-90
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• 2001

Several seismic traces of earthquakes observed from the digital new type seismograph instruments of KMA in 2000 were scanned. From these, good quality data which have high signal/noise ratio were selected and they were transformed into ascii data from binary data(min-seed format). The hypo71 program and P-S was applied in order to determine the location of epicenter, origin time and the magnitude. From these data, the 29 earthquakes, 358 seismic records consist of 587 directional components were calculated. Using these, ground acceleration data, acceleration, velocity, and displacemnet response spectrums of the structures were calculated and they could be represented in a picture by the form of tripartite response spectrum. In the result, response spectrums of the 587 directional components of the above seismic data records were obtained respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1675-1682
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• 2014

In this paper, we propose a precise time management and time synchronization based on real-time data storage and transmission scheme in design of seismic data acquisition system for urban earthquake disaster preventing system (UEDPS). It is possible to improve the performance of the existing research results through the proposed methods. To evaluate the performances of the proposed methods, we implemented a prototype system(H/W & S/W) and performed some experiments with real seismic data and test equipment generated data as the input.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1363-1373
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• 2022

The recent seismic events that occurred in South Korea have increased the interest in the re-evaluation of the seismic capacity of nuclear power plant (NPP) equipment, which is often conservatively estimated. To date, various approaches-including the Bayesian method proposed by the United States (US) Electric Power Research Institute -have been developed to quantify the seismic capacity of NPP equipment. Among these, the Bayesian approach has advantages in accounting for both prior knowledge and new information to update the probabilistic distribution of seismic capacity. However, data availability and region-specific issues exist in applying this Bayesian approach to Korean NPP equipment. Therefore, this paper proposes to construct an earthquake experience database by combining available earthquake records at Korean NPP sites and the general location of equipment within NPPs. Also, for the better representation of the seismic demand of Korean earthquake datasets, which have distinct seismic characteristics from those of the US at a high-frequency range, a broadband frequency range optimization is suggested. The proposed data construction and seismic demand optimization method for seismic capacity re-evaluation are demonstrated and tested on a 480 V motor control center of a South Korea NPP.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.269-276
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• 2016

Seismic performance evaluation of existing building usually needs much time and man power, especially in case of nonlinear analysis. Many data interaction steps for model transfer are needed and engineers should spend much time with simple works like data entry. Those time-consuming steps could be reduced by applying computerized and automated modules. In this study, computational platform for seismic performance evaluation was made with several computerized modules. StrAuto and floor load transfer module offers a path that can transfer most linear model data to nonlinear analysis model so that engineers can avoid a lot of repetitive work for input information for the nonlinear analysis model. And the new nonlinear property generator also helps to get the nonlinear data easily by importing data from structural design program. To evaluate the effect of developed modules on each stages, seismic performance evaluation of example building was carried out and the lead time was used for the quantitative evaluation.

• Geophysics and Geophysical Exploration
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• v.7 no.4
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• pp.245-250
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• 2004

Horizontal-axes on the seismic section have been represented in a distance unit by applying horizontal-distance correction transformation on a 2-D seismic section of single channel marine seismic data. By drawing horizontal-axes in a distance unit, distortion of horizontal distances shown on the seismic section when the ship speed varies during a survey can be diminished considerably. Position information obtained by GPS and stored in each trace of seismic data as well as data collection windows were used for horizontal distance correction. The minimum window length was decided by considering ship speed and shot interval, and the maximum window length wat determined by reflecting radius of the 1st Fresnel zone. In choosing an optimum window length, horizontal resolution and stacking effect were considered simultaneously. By applying horizontal distance correction we could get a 2-D seismic section which is considered at reflecting the real subsurface structure analogously.

• Structural Engineering and Mechanics
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• v.37 no.6
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• pp.575-592
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• 2011

For seismic resistant design of critical structures, a dynamic analysis, either response spectrum or time history is frequently required. Owing to the lack of recorded data and the randomness of earthquake ground motion that may be experienced by structure in the future, usually it is difficult to obtain recorded data which fit the requirements (site type, epicenteral distance, etc.) well. Therefore, the artificial seismic records are widely used in seismic designs, verification of seismic capacity and seismic assessment of structures. The purpose of this paper is to develop a numerical method using Artificial Neural Network (ANN) and wavelet packet transform in best basis method which is presented for the decomposition of artificial earthquake records consistent with any arbitrarily specified target response spectra requirements. The ground motion has been modeled as a non-stationary process using wavelet packet. This study shows that the procedure using ANN-based models and wavelet packets in best-basis method are applicable to generate artificial earthquakes compatible with any response spectra. Several numerical examples are given to verify the developed model.

• Earthquakes and Structures
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• v.8 no.5
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• pp.977-994
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• 2015

In this study, earthquake loads are investigated statistically and compared with the nominal earthquake loads calculated according to the Turkish Earthquake Code, namely: "Specifications for Structures to be Built in Earthquake Areas". For this purpose, the "actual" mean load values estimated from statistical methods and the nominal load values computed according the Seismic Code are compared, with respect to some variations in the basic parameters, such as the importance factor, building height, site coefficient, seismic zone and seismic load reduction factor. In addition to the data compiled from different regions of Turkey, the published data and information in the foreign literature are also used in the determination of the earthquake load statistics. Although the dead and live loads acting on a structure are independent of the geographical location of the structure, environmental loads, such as earthquake loads are highly dependent on the location of the structure. Accordingly, for the assessment of statistical parameters associated with earthquake loads, twelve different locations which can represent the different seismic zones of Turkey as accurately as possible are chosen. As a result of the code calibration procedure considered in this study, it is observed that the load values obtained from the Turkish Seismic Code may overestimate or underestimate the actual seismic loads in some of the seismic zones.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.6
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• pp.345-352
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• 2018

It is inevitable to use the distinct element method in the analysis of structural dynamics for stacked stone pagoda system. However, the experimental verification of analytical results produced by the discrete element method is not sufficient yet, and the theory of distinct element method is not universal in Korea. This study introduces how to model the stacked stone pagoda system using the distinct element method, and draws some considerations in the seismic analysis procedures. First, the rocking mode and sliding mode are locally mixed in the seismic responses. Second, the vertical stiffness and the horizontal stiffness on the friction surface have the greatest influence on the seismic behavior. Third, the complete seismic analysis of stacked stone pagoda system requires a set of the horizontal, vertical, and rotational velocity time histories of the ground. However, earthquake data monitored in Korea are limited to acceleration and velocity signals in some areas.

• Structural Engineering and Mechanics
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• v.31 no.5
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• pp.527-544
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• 2009

In this study, the periodic seismic performance evaluation scheme is proposed using a structural health monitoring system in terms of seismic fragility. An instrumented highway bridge is used to demonstrate the evaluation procedure involving (1) measuring ambient vibration of a bridge under general vehicle loadings, (2) identifying modal parameters from the measured acceleration data by applying output-only modal identification method, (3) updating a preliminary finite element model (obtained from structural design drawings) with the identified modal parameters using real-coded genetic algorithm, (4) analyzing nonlinear response time histories of the structure under earthquake excitations, and finally (5) developing fragility curves represented by a log-normal distribution function using maximum likelihood estimation. It is found that the seismic fragility of a highway bridge can be updated using extracted modal parameters and can also be monitored further by utilizing the instrumented structural health monitoring system.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.156-157
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• 2005

Gas hydrate is ice-like crystalline lattice, formed at appropriate temperature and pressure, in which gas molecules are trapped. It is worldwide popular interesting subject as a potential energy. In korea, a seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. In this paper, we had conducted numerical and physical modeling experiments for seismic properties on gas hydrate with field data which had been acquired over the East sea in 1998. We used a finite difference seismic method with staggered grid for 2-D elastic wave equation to generate synthetic seismograms from multi-channel surface seismic survey, OBC(Ocean Bottom Cable) and VSP(Vertical Seismic Profiling). We developed the seismic physical modeling system which is simulated in the deep sea conditions and acquired the physical model data to the various source-receiver geometry. We carried out seismic complex analysis with the obtained data. In numerical and physical modeling data, we observed the phase reversal phenomenon of reflection wave at interface between the gas hydrate and free gas. In seismic physical modeling, seismic properties of the modeling material agree with the seismic velocity estimated from the travel time of reflection events. We could easily find out AVO(Amplitude Versus Offset) in the reflection strength profile through seismic complex analysis.