• Earthquakes and Structures
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• 제6권4호
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• pp.375-392
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• 2014

Time history analyses have been preferred commonly in earthquake engineering area to determine earthquake performances of structures in recent years. Advances in computer technology and structural analysis have led to common usage of time history analyses. Eurocode 8 allows the use of real earthquake records as an input for linear and nonlinear time history analyses of structures. However, real earthquake records with the desired characteristics sometimes may not be found, for example depending on soil classes, in this case artificial and synthetic earthquake records can be used for seismic analyses rather than real records. Selected earthquake records should be scaled to a code design spectrum to reduce record to record variability in structural responses of considered structures. So, scaling of earthquake records is one of the most important procedures of time history analyses. In this paper, four real earthquake records are scaled to Eurocode 8 design spectrums by using SESCAP (Selection and Scaling Program) based on time domain scaling method and developed by using MATLAB, GUI software, and then scaled and real earthquake records are used for linear time history analyses of a six-storied building. This building is modeled as spatial by SAP2000 software. The objectives of this study are to put basic procedures and criteria of selecting and scaling earthquake records in a nutshell, and to compare the effects of scaled earthquake records on structural response with the effects of real earthquake records on structural response in terms of record to record variability of structural response. Seismic analysis results of building show that record to record variability of structural response caused by scaled earthquake records are fewer than ones caused by real earthquake records.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1389-1396
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• 2008

The recent Sichuan earthquake(2008) in China and Iwate-Miyazaki earthquake(2008) in Japan give Korea peninsula warning that it is no more safety zone against damage by earthquake events. So, rapid and appropriate countermeasures for dam operation and management against earthquake are needed. In Korea earthquake design standard(MOCT, 1997) has been revised after Kobe earthquake. Installation of seismometer and monitoring of earthquake for special class dams is requlated in dam aseismic design standard(MOCT, 2001). Accelerometer installation project for existing dams has been carrying out by K-water to establish an earthquake network for dam safety. Real-time dam earthquake monitoring network has also been developed to detect an earthquake efficiently and to warn to dam administrators as soon as possible. In this study, dam real-time earthquake monitoring system developed by K-water was introduced and applicability of real earthquake record measured by this system to dam safety management was illustrated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.569-576
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• 2003

Based on the equivalent uniform stress concept Presented by Seed and Idriss, sinusoidal cyclic loads which simplified earthquake loads have been applied in evaluating the liquefaction resistance strength experimentally. However, the liquefaction resistance strength of soil based on the equivalent uniform stress concept can not exactly reflect the dynamic characteristics of the irregular earthquake motion. The liquefaction assessment method which was invented by using the equivalent uniform stress concept is suitable for the severe earthquake region such as Japan or USA, so the proper method to Korea is needed. In this study, estimation of the resistance to liquefaction was conducted by applying real earthquake loading to the cyclic triaxial test. From the test results, the characteristics of the fine sand under moderate earthquake were analyzed and compared with the results under strong earthquakes. Typically real earthquake loads used in this study are divided into two types - impact type and vibration type. Furthermore, results of the liquefaction resistance strength based on the equivalent uniform stress concept and tile concept using real earthquake loading were compared.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.213-217
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• 2000

It is essential to establish an earthquake alert system real-time seismographic data acquisition and data transmission by dedicated communications,. Up to now approximately 60 earthquake stations are installed in Korea and being operated by KMA. KEPRI,. KINS and KIGAM and its number will be increased in time. The earthquake data recorded in half of these stations are transmitted to data center and analysed in quasi real-time. Therefore if these real-time seismographic stations be connected to each organization by dedicated lines and we will develop an algorithm which we can calculate the magnitude and epicenter within 25-30 seconds after an earthquake occurred it will be possible to develop an Earthquake Alert System giving several tens of seconds warning in advance.

• 한국지진공학회논문집
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• 제18권1호
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• pp.29-36
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• 2014

In industrial facilities sites, the conventional method determining the earthquake magnitude (M) using earthquake ground-motion records is generally not applicable due to the poor quality of data. Therefore, a new methodology is proposed for determining the earthquake magnitude in real-time based on the amplitude measures of the ground-motion acceleration mostly from S-wave packets with the higher signal-to-ratios, given the Vs30 of the site. The amplitude measures include the bracketed cumulative parameters and peak ground acceleration (As). The cumulative parameter is either CAV (Cumulative Absolute Velocity) with 100 SPS (sampling per second) or BSPGA (Bracketed Summation of the PGAs) with 1 SPS. The arithmetic equations to determine the earthquake magnitude are derived from the CAV(BSPGA)-As-M relations. For the application to broad ranges of earthquake magnitude and distance, the multiple relations of CAV(BSPGA)-As-M are derived based on worldwide earthquake records and successfully used to determine the earthquake magnitude with a standard deviation of ${\pm}0.6M$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.320-327
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• 2005

Liquefaction characteristics of saturated sand under various dynamic loadings such as sinusoidal, wedge, increasing wedge and real earthquake loading are investigated focusing on the excess pore water pressure build up instead of liquefaction resistance strength in this paper. There are large differences between two types of earthquake loading - impact and vibration in liquefaction characteristics. The angle of phase change line of sinusoidal loading is very close to the vibration type, whereas the cumulative deviator stress and cumulative plastic strain are larger than two types of real earthquake loadings. On the other hand, the liquefaction characteristics of increasing wedge loadings are located in the range between vibration and impact earthquake loadings. It is concluded that the sinusoidal loading overestimates the resistance of soil under real earthquake loading. Based on results obtained, the increasing wedge loading can reflect the liquefaction behavior under real earthquake loadings more efficiently than sinusoidal loading based on equivalent uniform stress concept.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.306-309
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• 2022

최근 우리나라에서도 지진 발생빈도가 급격히 증가하면서 지진에 대한 관심도가 높아지고 있다. 지진발생 시 대응과 복구도 중요하지만, 관리 취약점을 사전에 찾아내어 예방 및 사전 대비 활동을 수행하는 것이 필요하다. 한국수자원공사에서는 지진으로부터 안전한 시설관리를 위해 지진가속도계측기를 운영하여 실시간 지진데이터를 수집하고 있으며, 대외기관에서 지진데이터를 활용할 수 있도록 데이터를 전송하고 있다. 운영 중인 지진감시시스템의 관리 취약점을 사전에 줄이고자 지진데이터의 수집지연시간을 최소화하고, 빅데이터를 활용한 지진데이터의 실시간 품질분석 체계·기반 구축으로 고품질의 데이터 생산이 가능하다. 이에 따라 댐 안전관리 및 고품질의 지진데이터를 확보하여 대외기관에 신속한 데이터를 제공함으로써 지진재해로부터 국민의 생명과 재산을 보호할 수 있을 것으로 기대된다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.67-74
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• 2002

An experimental assessment on the dynamic behavior of saturated sand which can consider the irregular characteristics of earthquakes was proposed. The equivalent uniform stress concept presented by Seed and Idriss has been applied to evaluate the liquefaction resistance strength to simplify earthquake loading. However, it was known that the liquefaction resistance strength of soil based on the equivalent uniform stress concept can't exactly mirror the dynamic characteristics of the irregular earthquake motion. In this study, estimation of the criterion of the liquefaction resistance strength was determined by applying real earthquake loading to the cyclic triaxial test. From the test results, relationships between excess pore water pressure and the earthquake characteristics such as magnitude or duration were determined. Magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were also proposed.

• 한국지진공학회논문집
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• 제11권2호
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• pp.81-94
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• 2007

지진시 발생하는 지반 액상화 현상은 지진피해예측시 가장 중용하게 평가해야 하는 항목으로 실내에서 액상화 현상을 시뮬레이션하는 경우, 불규칙성의 지진을 제어하기 어려운 이유로 등가반복형태의 정현파 또는 쐐기파를 이용하는 것이 통상적이었다. 그러나, 90년대 이후 컴퓨터의 발달과 함께한 신호처리 및 제어기술의 급속한 발전은 동역학분야에서의 실험연구에 큰 도움을 주었으며 지반진동분야의 경우, 진동대 및 원심모형기와 같은 대형지진모의시험에서 실지진하중을 이용한 연구사례들이 증가되고 있는 실정이다. 국내에서도 실지진하중재하가 가능한 요소시험결과에 대한 연구사례가 발표되는 등 이에 관한 연구가 활발하게 진행되고 있으며 특히, 실지진하중 시험결과로부터 실지진하중하에서의 과잉간극수압의 변화가 정현하중시험에서의 결과와 큰 차이를 보이고 있다는 분석결과가 발표되어 현재까지 지반동역학분야에서 지진하중의 불규칙성을 크게 고려하지 않았던 통상적 가정사항들이 문제점으로 대두되어 관심을 집중시키고 있다. 본 연구에서는 등가의 정현파 및 쐐기파와 증가형태의 쐐기파, 그리고 실지진파 등 다양한 진동하중을 재하할 수 있는 삼축압축시험기를 이용하여 기존의 유효응력개념에서 사용하는 과잉간극수압관련 매개변수인 소성일, 전단소성 변형률 상각궤도, 그리고 액상화 상태전환선의 기울기를 비교분석하였으며 하중변화에 따른 토립자의 변형과 간극수압의 변화를 상세분석하였다. 연구결과, 토립자의 변형, 간극수의 동적흐름, 동적흐름 속도수두의 압력수두로의 전환, 그리고 과잉간극수압의 증가로 표현되는 새로운 개념의 액상화 발생이론을 제안하였으며 그 타당성 검토를 위해 과잉간극수압과 동적흐름의 압력수두(흐름속도의 제곱값)와의 상관관계를 비교하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.58-65
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• 2001

It is essential to know exactly what the response of the seismograph is inclusive of characteristic of the seismic sensors before using it for detailed seismic study. This is because the recorded earthquake data can be more or less affected by the overall system and need to be corrected properly to the analysis`s best to obtain the right results. In this respect, two basic earthquake data processing techniques are introduced and applied, for validation purpose, to real data from KEPRI seismic monitoring system which were established for determining the site-specific characteristics of the earthquakes around the Nuclear Power Plants. One is conventional instrumental correction technique for velocity data and the other is for removing acausal ringing originate from using linear phase FIR filter. These techniques are all implemented in the time domain using digital filtering process and shows the desired results when applied to real earthquake data.