• The Journal of Engineering Geology
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• v.24 no.1
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• pp.123-135
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• 2014

Earthquakes can cause serious loss of life and significant property damage. Thus, the study of active faults is important in evaluating future fault activity and hazards caused by future earthquake events. Structural mapping and the tracing of active faults are the primary steps in studies of active faults. Until now, active faults in South Korea have been mapped using aerial photography, satellite images, and low-quality DEMs. Lineament analysis as a means of identifying active faults is relatively difficult in Korea due to geological characteristics (weak tectonic activity) and dense vegetation cover. In this paper, we introduce the basic concept of the LiDAR technique (a new prospective remote sensing method) and a data analysis method that can overcome these problems. This paper will contribute to a better understanding of the airborne LiDAR technique and its application to South Korea. Some preliminary results from Korean and USA LiDAR data show the usefulness of this technique for tracing lineaments, active faults, and terraces in South Korea.

• Journal of the Society of Disaster Information
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• v.12 no.3
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• pp.261-272
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• 2016

The whole world has been damaged by dramatic increase of natural disasters such as localized torrential downpour, earthquake and drought, while suffering from climate changes caused by global warming. In Korea where the continental climate and oceanic one are crossed, the frequency and the size of damages are increased by stronger typhoons and localized torrential downpours and landslides, storms and floods. Therefore, this study analyzed damage cases and their causes and examined foreign plans to prevent natural disasters, by limiting to rural villages where serious damages occur due to typhoons and localized torrential downpours and measures and infra-structures against such disasters are poorly prepared. From the findings, it attempts to suggest some plans to establish disaster safety villages by abstracting plan factors applicable to rural areas in Korea, on the basis of facilities and spatial projects.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.191-199
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• 2003

The inelastic response of many structural steel and reinforced concrete structures subject to extreme loadings can be characterized by elastoplastic behaviors. Although excursion beyond the elastic range is usually not permitted under normal conditions of service, the extent of permanent damage a structure may sustain when subjected to extreme conditions, such as severe blast or earthquake loading, is frequently of interest to the engineer. A blast is usually the result of an explosion defined as a "sudden expansion". This paper discusses the basic concept that defines blast loadings on structures and corresponding elastoplastic structural response (displacement, velocity, and acceleration) and try to explain a crack propagation of concrete in sudden expansion. According to nonlinear finite element analysis, the crack forms of static and dynamic states displayed different in RC structural members. This paper also provides useful data for the dynamic fracture analysis of RC frame structures.

• Earthquakes and Structures
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• v.17 no.5
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• pp.511-519
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• 2019

The concrete gravity dam is one of the most important parts of the nation's infrastructure. Besides the benefits, the dam also has some potentially catastrophic disasters related to the life of citizens directly. During the lifetime of service, some degradations in a dam may occur as consequences of operating conditions, environmental aspects and deterioration in materials from natural causes, especially from dynamic loads. Cumulative Absolute Velocity (CAV) plays a key role to assess the operational condition of a structure under seismic hazard. In previous researches, CAV is normally used in Nuclear Power Plant (NPP) fields, but there are no particular criteria or studies that have been made on dam structure. This paper presents a method to calculate the limitation of CAV for the Bohyeonsan Dam in Korea, where the critical Peak Ground Acceleration (PGA) is estimated from twelve sets of selected earthquakes based on High Confidence of Low Probability of Failure (HCLPF). HCLPF point denotes 5% damage probability with 95% confidence level in the fragility curve, and the corresponding PGA expresses the crucial acceleration of this dam. For determining the status of the dam, a 2D finite element model is simulated by ABAQUS. At first, the dam's parameters are optimized by the Minitab tool using the method of Central Composite Design (CCD) for increasing model reliability. Then the Response Surface Methodology (RSM) is used for updating the model and the optimization is implemented from the selected model parameters. Finally, the recorded response of the concrete gravity dam is compared against the results obtained from solving the numerical model for identifying the physical condition of the structure.

• Journal of the Korean Geophysical Society
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• v.7 no.2
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• pp.89-97
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• 2004

Earthquake records written in the history documents such as “SeungJeongWon IlKi” and “Chosun Wangjo Shilok” for the earthquakes occurred around the offshore near Yangyang and Samcheok area in June, 1681, have been analyzed to estimate the intensity distribution and epicenters as well as magnitudes. Three consecutive earthquakes were analysed, which occurred near those area on June 12, 17, and 26, 1681. The Main-shock occurred on June 12, 1681 was felt in almost every provinces of Korea while after-shocks occurred on June 17 and 26, 1681, were felt in several provinces restrictively. Although the main-shock was felt in the entire provinces, the real damage had been concentrated in Kangwon province. A block of rock collapsed to fall due to main-shock in the mountain near Samcheok. No other man casualties were reported except a death due to being thrown off a horse by ground shaking in Seoul. Local micro-tsunami seems to be generated at the offshore of Samcheok due to the main-shock. The main-shock seems to be occurred in the offshore between Yangyang and Samcheok (38.0oN and 129.0oE) , the epicenter intensity and magnitude of which is over 8 in MMI and 6½ in Ms, respectively.

• Korean Journal of Remote Sensing
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• v.37 no.6_2
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• pp.1785-1791
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• 2021

Natural and environmental disasters are recently increasing in frequency and complexity worldwide due to the rapid expansion of overpopulation, industrialization, and urbanization. Thus, analyzing past critical events/disasters in deep and preparing for future disasters in terms of risk identification, assessment and management are imperative requirements. In this special issue, we introduce several interesting studies covering disaster risk management and observation technologies for the heat waves, particulate matters, floods, drought, and earthquake using remote sensing and GIS performed by i-SEED (School of Integrated Science for Sustainable Earth & Environmental Disaster at Pukyong National University). We expect that the results of this special issue provide comprehensive information on the risk management and damage prevention of natural and environmental disasters and offer guidance on the application to future disasters to reduce their risks and impacts.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.84-89
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• 2021

In 2017, the Gyeongju earthquake caused many casualties and considerable property damage by overturning and dropping blocks and bricks. Various reinforcement techniques were proposed, but some problems, such as short length or difficult construction, were encountered. Therefore, this study proposes a long-rawlplug screw anchor to improve the existing rawlplug anchor and conducts an experiment to evaluate the pullout strength. Variables in the pullout test were the compressive strength of concrete and the embedded length of the long-rawlplug screw anchor. According to the results, the pullout strength of the long-rawlplug screw anchor increased as the compressive strength of concrete increased, and they were not affected by the embedded length. Rather, it was found that the screw length of the long-rawlplug was important to the pullout strength.

• Earthquakes and Structures
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• v.15 no.6
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• pp.639-654
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• 2018

Rocking motion have been used for achieving the 'resilient buildings' against earthquakes in recent studies. Low-rise buildings, unlike the tall ones, because of their small aspect ratio tend to slide rather than move in rocking mode. However, since rocking is more effective in seismic response reduction than sliding, it is desired to create rocking motion in low-rise buildings too. One way for this purpose is making the building's structure rock on its internal bay(s) by reducing the number of bays at the lower part of the building's skeleton, giving it a mushroom form. In this study 'mushroom skeleton' has been used for creating multi-story rocking regular steel buildings with square plan to rock on its one-by-one bay central lowest story. To show if this idea is effective, a set of mushroom buildings have been considered, and their seismic responses have been compared with those of their conventional counterparts, designed based on a conventional code. Also, a set of similar buildings with skeleton stronger than code requirement, to have immediate occupancy (IO) performance level, have been considered for comparison. Seismic responses, obtained by nonlinear time history analyses, using scaled three-dimensional accelerograms of selected earthquakes, show that by using appropriate 'mushroom skeleton' the seismic performance of buildings is upgraded to mostly IO level, while all of the conventional buildings experience collapse prevention (CP) level or beyond. The strong-skeleton buildings mostly present IO performance level as well, however, their base shear and absolute acceleration responses are much higher than the mushroom buildings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.154-162
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• 2019

Large scale damage has been globally increased due to natural disasters such as earthquake. Although a variety of studies secured seismic performance of buildings, casualties and economic loss have occurred because of poor security of seismic performance in non-structural components. Structure's location on which non-structural components are installed and characteristics of vibration occurring on each position of structures are varied, so a response spectrum is required for each position of structures. In addition, a response spectrum occurring in a structure is different, depending on the form of it and positions on which it is installed. Therefore, selection of a response spectrum is important, so a definite method for calculating the response spectrum which acts on non-structural components is necessary. A method for choosing a response spectrum is suggested in this paper, and a structural analysis was conducted with the suggested method, by selecting a ground response spectrum and a structural system, which may occur in Korea. Moreover, it helps create a response spectrum necessary for a seismic test of non-structural components, by suggesting the method for deduction it, with a simple formula.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.4
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• pp.205-213
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• 2019

In the Pohang Earthquake in 2017, considerable damage to non-structural elements, such as ceiling systems, exterior finishes, and curtain walls, was reported; thus, the seismic designs of non-structural elements are important. In this study, the modal characteristics of a ceiling system were investigated through the impact hammer test. The frequency and damping ratio according to the length of the hanger bolt were identified. In addition, collision experiments were conducted to obtain the impact duration for exactly considering the impact effects of the ceiling against a wall or other adjacent elements. Based on the identified dynamics and impact duration of the ceiling system, the seismic responses of the ceiling system were obtained numerically in case of collision. Numerical simulation results show that the impact load tends to increase with the clearance between the ceiling and adjacent elements, and is not correlated with the length of the hanger bolt.