• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.963-978
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• 2020

Earthquakes can induce a large number of landslides and cause very serious property damage and human casualties. There are two issues in study on earthquake-induced landslides: (1) slope stability analysis under seismic loading and (2) debris flow run-out analysis. This study aims to review technical studies related to the development and application of earthquake-induced landslide models (seismic slope stability analysis). Moreover, a pilot application of a physics-based slope stability model to Mt. Umyeon, in Seoul, with several earthquake scenarios was conducted to test regional scale seismic landslide mapping. The earthquake-induced landslide simulation model can be categorized into 1) Pseudo-static model, 2) Newmark's dynamic displacement model and 3) stress-strain model. The Pseudo-static model is preferred for producing seismic landslide hazard maps because it is impossible to verify the dynamic model-based simulation results due to lack of earthquake-induced landslide inventory in Korea. Earthquake scenario-based simulation results show that given dry conditions, unstable slopes begin to occur in parts of upper areas due to the 50-year earthquake magnitude; most of the study area becomes unstable when the earthquake frequency is 200 years. On the other hand, when the soil is in a wet state due to heavy rainfall, many areas are unstable even if no earthquake occurs, and when rainfall and 50-year earthquakes occur simultaneously, most areas appear unstable, as in simulation results based on 100-year earthquakes in dry condition.

• Magazine of the Korea Concrete Institute
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• v.5 no.2
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• pp.2-8
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• 1993

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.765-779
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• 2019

Most of the existing evaluation criteria of vibration serviceability rely on the peak acceleration of the structure rather than that of the people keeping their own body unmoved on the structure who is the real receiver of structural vibrations. In order to accurately assess the vibration serviceability, therefore, a full path assessment approach of vibration serviceability based on vibration source, path and receiver is not only tentatively proposed in this paper, taking the peak acceleration of receiver into account, but also introduce a probability procedure to provide more instructive information instead of a single value. In fact, semi-rigid supported on both sides of the structure is more consistent with the actual situation than simply supported or clamped due to the application of the prefabricated footbridge structures. So, the footbridge is regarded as a beam with semi-rigid supported on both sides in this paper. The differential quadrature-integral quadrature coupled method is not only to handle different type of boundary conditions, but also after being further modified via the introduction of an approximation procedure in this work, the time-varying system problem caused by human-structure interaction can be solved well. The analytical results of numerical simulations demonstrate that the modified differential quadrature-integral quadrature coupled method has higher reliability and accuracy compared with the mode superposition method. What's more, both of the two different passive control measures, the tuned mass damper and semi-rigid supported, have good performance for reducing vibrations. Most importantly, semi-rigid supported is easier to achieve the objective of reducing vibration compared with tuned mass damper in design stage of structure.

• Journal of the Society of Disaster Information
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• v.11 no.2
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• pp.227-234
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• 2015

In this study, the theoretical review was carried out on the concepts regarding the continuity of operation plan and business continuity management plan, international standard ISO22301 and common required functions for disaster response, and the business continuity guideline of local governments in Japan and establishment cases were analyzed to draw matters to be reflected for establishing the business continuity plan of local governments according to the occurrence of earthquake and tsunami. In conclusion, the standard guideline of central government should be prepared for establishing the business continuity plan of local governments and the foundation to establish the plan smoothly based on such guideline should be provided. Also, the business continuity plan should be prepared based on the previous established safety management plans by reflecting the regional characteristics of local governments. And, in order to establish the business continuity plan that fits the region, proper investigations can be carried out to examine the characteristics of each organizations, resources, facilities and environments. Lastly, detailed scenario on the scale of earthquake and tsunami occurrence and damages is prepared to establish the business continuity plan of local governments and conditions for prompt countermeasures according to the scale.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.33-36
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• 2008

In Korean Building Code 2005(KBC-2005), the Seismic Zone Factor is regulated by separating the seismic zone into two part. This seismic zone factor is not matched to regional seismic characteristics of our country because the factor is based on International Building Code 2000 (IBC-2000) of USA. This study inquiry for having a sufficient grasp of the seismic characteristics of south Korea region and appling for the seismic cope plan. We have collected and analyzed earthquake record happened in domestic region. There are two kinds of earthquake record. One is Historical earthquake data, another is Instrumental earthquake data. I used Instrumental earthquake record data which reliance is higher than historical earthquake data for proposing attenuation formulas by analyzing a correlation the epicenter and the distance.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.395-418
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• 2024

The epicentral region of earthquakes is typically where liquefaction-related damage takes place. To determine the maximum distance, such as maximum epicentral distance (R_e), maximum fault distance (R_f), or maximum hypocentral distance (R_h), at which an earthquake can inflict damage, given its magnitude, this study, using a recently updated global liquefaction database, multiple ML models are built to predict the limiting distances (R_e, R_f, or R_h) required for an earthquake of a given magnitude to cause damage. Four machine learning models LSTM (Long Short-Term Memory), BiLSTM (Bidirectional Long Short-Term Memory), CNN (Convolutional Neural Network), and XGB (Extreme Gradient Boosting) are developed using the Python programming language. All four proposed ML models performed better than empirical models for limiting distance assessment. Among these models, the XGB model outperformed all the models. In order to determine how well the suggested models can predict limiting distances, a number of statistical parameters have been studied. To compare the accuracy of the proposed models, rank analysis, error matrix, and Taylor diagram have been developed. The ML models proposed in this paper are more robust than other current models and may be used to assess the minimal energy of a liquefaction disaster caused by an earthquake or to estimate the maximum distance of a liquefied site provided an earthquake in rapid disaster mapping.

• Geomechanics and Engineering
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• v.37 no.6
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• pp.565-576
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• 2024

In this study, the earthquake risk assessment of single-story RC precast buildings in Turkey was carried out using loss curves. In this regard, Kocaeli, a seismically active city in the Marmara region, and this building class, which is preferred intensively, were considered. Quality and period parameters were defined based on structural and geometric properties. Depending on these parameters, nine main sub-classes were defined to represent the building stock in the region. First, considering the mean fragility curves and four different central damage ratio models, vulnerability curves for each sub-class were computed as a function of spectral acceleration. Then, probabilistic seismic hazard analyses were performed for stiff and soft soil conditions for different earthquake probabilities of exceedance in 50 years. In the last step, 90 loss curves were derived based on vulnerability and hazard results. Within the scope of the study, the comparative parametric evaluations for three different earthquake intensity levels showed that the structural damage ratio values for nine sub-classes changed significantly. In addition, the quality parameter was found to be more effective on a structure's damage state than the period parameter. It is evident that since loss curves allow direct loss ratio calculation for any hazard level without needing seismic hazard and damage analysis, they are considered essential tools in rapid earthquake risk estimation and mitigation initiatives.

• The Journal of Korean Academic Society of Nursing Education
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• v.18 no.3
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• pp.424-435
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• 2012

Purpose: The purpose of this study was to investigate the disaster experience (accidents, education etc) and the concern for disaster preparedness of college students. Methods: This research design was a descriptive study. Data were collected from November 1, 2011 to December 30, 2011 and analyzed by the SPSS PASW statistics 18.0 program. Results: There were statistical significances in major (p<.050), grade(p<.001), and a completed disaster class(p<.001) between general characteristics and concern for disaster preparedness. The major disaster events that occurred from 2003 to 2010 in Korea were the 2007 Taean oil spill (85.4%), the 2003 Daegu subway fire (82.7%), and the 2008 Sungnyemun fire (62.9%). The possible disaster events in Korea were hurricanes, floods, fires (including wildfire), and the shutdown of communication lines. Subjects learned about cardiopulmonary resuscitation (18.2%), first aid for bleeding and fractures (17.8%), a fire drill (14.3%), and an escape drill for an earthquake (14.0%). They wanted to learn the fire drill (11.33%), the escape drill for an earthquake (9.7%), a war drill (9.0%), a disaster confrontation drill on the subway (8.6%), and a fire and explosion evacuation drill (8.4%). Half of subjects were not prepared with emergency supplies for disasters because they thought that a disaster would not occur. Conclusion: It is necessary to develop the disaster educational programs according to subject's demands in Korea.

• The Journal of Engineering Geology
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• v.28 no.2
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• pp.313-324
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• 2018

In order to study the earthquake precursor in the Korean peninsula, long-term variations of chemical composition, radon-222, and water level were measured at depths (-60 m, -100 m) in the groundwater monitoring wells of the Daejeon and the Cheongwon area. The pH and electrical conductivity of groundwater in the monitoring wells showed some relationship with the Pohang earthquake. The ${HCO_3}^-$ and $Cl^-$ concentration of groundwater in the Daejeon and $Mg^{2+}$, $Cl^-$ and ${NO_3}^-$ in the Cheongwon showed some relation with the Pohang earthquake. However, it is not distinct to find the relationship between their variation and earthquake. The radon-222 concentration in Daejeon was observed a significant increase from a minimum of 162 Bq/L prior to the earthquake to 573 Bq/L right after the earthquake, that indicating a strong correlation with earthquakes. In the case of groundwater levels, it can not find some correlation between earthquakes and continuous decreasing trend in the monitoring wells of Daejeon and Cheongwon area. However, water level of a national groundwater observation well within 10 kilometers of Pohang epicenter was recorded as an abrupt drop right before the earthquake. Conclusively, although the location of monitoring wells is more than 180 kilometers apart from the epicenter of the Pohang earthquake, the radon gas in groundwater can be considered as a reliable candidate among earthquake precursors. The pH, electrical conductivity, ${HCO_3}^-$ and $Cl^-$ among hydrochemicals showed some correlation with earthquake should be monitored during a longer term to recognize distinctly as a precursor of earthquake.

• Earthquakes and Structures
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• v.18 no.4
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• pp.467-480
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• 2020

Concrete rectangular liquid storage tanks are widely used, but there are many cases of damage in previous earthquakes. Nonlinear fluid-structure interaction (FSI) is considered, Mooney-Rivlin material is used for rubber bearing, nonlinear contact is used for sliding bearing, numerical calculation models of no-isolation, rubber isolation, sliding isolation and hybrid isolation concrete rectangular liquid storage tanks are established; dynamic responses of different structures are compared to verify the effectiveness of isolation methods; and influences of earthquake amplitude, bidirectional earthquake and far-field long-period earthquake on dynamic responses are investigated. Results show that for liquid sloshing wave height, rubber isolation cause amplification effect, while sliding isolation and hybrid isolation have reduction effect; displacement of rubber isolation structure is much larger than that of sliding isolation with limiting-devices and hybrid isolation structure; when PGA is larger, wall cracking probability of no-isolation structure becomes larger, and probability of liquid sloshing wave height and structure displacement of rubber isolation structure exceeds the limit is also larger; under bidirectional earthquake, occurrence probabilities that liquid sloshing wave height and structure displacement of rubber isolation structure exceed the limit will be increased; besides, far-field long-period earthquake mainly influences structure displacement and liquid sloshing wave height. On the whole, control effect of sliding isolation is the best, followed by hybrid isolation, and rubber isolation is the worst.