• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.179-185
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• 2020

Recently, in order to improve the performance of the Earthquake Early Warning System (EEWS) and to supplement the effects of earthquake disaster prevention in epicenters or near epicenters, development of on-site EEWS has been attempted. Unlike the national EEWS, which is used for earthquake disaster prevention by using seismic observation networks for earthquake research and observation, on-site EEWS aims at earthquake disaster prevention and therefore requires efficient design and evaluation in terms of performance and cost. At present, Korea lacks the necessary core technologies and operational know-how, including the use of existing EEWS design criteria and evaluation methods for the development of On-Site EEWS as well as EEWS. This study proposes hardware and software design directions and performance evaluation items and methods for seismic data collection, data processing, and analysis for localization of On-Site EEWS based on the seismic accelerometer requirements of the Seismic and Volcanic Disaster Response Act.

• Steel and Composite Structures
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• v.26 no.1
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• pp.55-66
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• 2018

In this paper, the response of an underground fibreglass reinforced plastic (FRP) composite pipe system subjected to realistic loading scenarios that may be experienced by an actual buried pipeline is investigated. The model replicates an arbitrary site with a length of buried pipeline, passing through a $90^{\circ}$ bend and into a valve pit. Various loading conditions, which include effects of pipe pressurization, differences in response between stainless steel and fibreglass composite pipes and severe loss of bed-soil support are studied. In addition to pipe response, the resulting soil stresses and ground settlement are also analysed. Furthermore, the locations of potential leakage and burst have also been identified by evaluating the contact pressures at the joints and by comparing stresses to the pipe hoop and axial failure strengths.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.821-845
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• 2016

Extensive researches on distribution of earthquake induced damages in different regions have shown that geological and geotechnical conditions of the local soils significantly influence behavior of alluvial areas under seismic loading. In this article, the site of Babol city which is formed up of saturated fine alluvial soils is considered as a case study. In order to reduce the uncertainties associated with earthquake resistant design of structures in this area (Babol city), the required design parameters have been evaluated with consideration of site's dynamic effects. The utilized methodology combines experimental ground ambient noise analysis, expressed in terms of horizontal to vertical (H/V) spectral ratio, with numerical one-dimensional response analysis of soil columns using DEEPSOIL software. The H/V spectral analysis was performed at 60 points, experimentally, for the region in order to estimate both the fundamental period and its corresponding amplification for the ground vibration. The investigation resulted in amplification ratios that were greater than one in all areas. A good agreement between the proposed ranges of natural periods and alluvial amplification ratios obtained through the analytical model and the experimental microtremor studies verifies the analytical model to provide a good engineering reflection of the subterraneous alluviums.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.2
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• pp.111-119
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• 2020

Recently, some of the most destructive earthquakes have occurred in South Korea since earthquake observations began in 1978. In particular, the soil liquefactions have been reported in Pohang as a result of the ML 5.4 earthquake that occurred in November 2017. Liquefaction-induced ground deformations can cause significant damage to a wide range of buildings and infrastructures. Therefore, it is necessary to take practical steps to ensure safety during an earthquake. In the current seismic design in South Korea, the Hachinohe earthquake and Ofunato earthquake recorded in Japan, along with artificial earthquakes, have been generally used for input motions in dynamic analyses. However, such strong ground motions are only from Japan, and artificial earthquake ground motions are different from real ground motions. In this study, seven ground motions are selected, including those recorded in South Korea, while others are compatible to the current design spectra of South Korea. The effects of the newly selected ground motions on site response analyses and liquefaction analyses are evaluated.

• Earthquakes and Structures
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• v.8 no.3
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• pp.681-697
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• 2015

Iran as one of the countries located on the Alpine-Himalayan seismic belt has recently experienced a few number of catastrophic earthquakes. A well-known index of how buildings are affected by earthquakes is through assessment of probable Peak Ground Acceleration (PGA) and structures' response spectra. In this research, active faults around Kerman and Birjand, two major cities in eastern parts of Iran, have been considered. Seismic catalogues are gathered to categorize effects of surrounding faults on seismicity of the region. These catalogues were further refined with respect to time and space based on Knopoff-Gardner algorithm in order to increase statistical independency of events. Probabilistic Seismic Hazard Analysis (PSHA) has been estimated for each of cities regarding 50, 100, 200 and 500 years of structures' effective life-span. These results subsequently have been compared with Deterministic Seismic Hazard Analysis (DSHA). It has been observed that DSHA not necessarily suggests upper bound of PSHA results. Furthermore, based on spectral Ground Motion Prediction Equations (GMPEs), Uniform Hazard Spectra (UHS) and spectral acceleration were provided for 2% and 10% levels of probability of exceedance. The results show that increasing source-to-site distance leads to spectral acceleration reduction regarding each fault. In addition, the spectral acceleration rate of variation would increase if the source-to-site distance decreases.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.6
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• pp.253-257
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• 2007

Among the arthritis symptoms, chronic pain is the most serious, and it can profoundly affect the quality of human life. Unfortunately, the mechanism of development in arthritis and arthritic pain has not yet been precisely elucidated. Accumulating evidence indicates that nitric oxide (NO) plays a pivotal role in nociceptive processing in the spinal cord. However, the modulation mechanism of NO in the peripheral site of arthritis and arthritic pain has not been clarified. Therefore, I determined in the present study which nitric oxide synthase (NOS) was involved in the induction of arthritis and arthritic pain. Monoarthritis was induced by intra-articular injection of carrageenan (2%, $50{\mu}l$) into rats, and resulted in the reduction of weight load on the injected leg, increase of knee joint diameter and inflammatory response. Pre-treatment of rats with L-N6-(1-iminoethyl)-lysine (L-NIL, $500{\mu}g$, in $50{\mu}l$), an inhibitor of inducible NOS (iNOS), partially prevented the induction of pain-related behavior and partially reduced inflammatory response in the synovial membrane in the knee joint. These results suggest that iNOS in the knee joint may play an important role in the induction of pain-related behavior and inflammation, and that NO produced by iNOS may be associated with nociceptive signaling in the peripheral site.

• Steel and Composite Structures
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• v.46 no.4
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• pp.577-589
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• 2023

In this study, on-site testing was carried out to investigate the vibration performance of a cold-formed thin-walled steel floor system. Ambient vibration, walking excitation (single and double persons), and impulsive excitation (heel-drop and jumping) were considered to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes) and vertical acceleration response. Meanwhile, to discuss the influence of cement fiberboard on structural vibration, the primary vibration parameters were compared between the systems with and without the installation of cement fiberboard. Based on the experimental analysis, the cold-formed thin-walled steel floor possesses high frequency (> 10 Hz) and damping (> 2%); the installed cement fiberboard mainly increases the mass of floor system without effectively increasing the floor stiffness and may reduce the effects of primary vibration parameters on acceleration response; and the human-structure interaction should be considered when analyzing the vibration serviceability. The comparison of the experimental results with those in the AISC Design Guide indicates that the cold-formed thin-walled steel floor exhibits acceptable vibration serviceability. A crest factor 𝛽_rp (ratio of peak to root-mean-square accelerations) is proposed to determine the root-mean-square acceleration for convenience.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.38-50
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• 2008

The site-specific seismic responses and corresponding seismic hazards are influenced mainly by the subsurface geologic and geotechnical dynamic characteristics. To estimate reliably the seismic responses in this study, a geotechnical information system (GTIS) within GIS framework was developed by introducing new concepts, which consist of the extended area containing the study area and the additional site visit for acquiring surface geo-knowledge data. The GIS-based GTIS was built for Gyeongju area, which has records of abundant historical seismic hazards reflecting the high potential of future earthquakes. At the study area, Gyeongju, intensive site investigations and pre-existing geotechnical data collections were performed and the site visits were additionally carried out for assessing geotechnical characteristics and shear wave velocity ($V_S$) representing dynamic property. Within the GTIS for Gyeongju area, the spatially distributed geotechnical layers and $V_S$ in the entire study area were reliably predicted from the site investigation data using the geostatistical kriging method. Based on the spatial geotechnical layers and $V_S$ predicted within the GTIS, a seismic zoning map on site period ($T_G$) from which the site-specific seismic responses according to the site effects can be estimated was created across the study area of Gyeongju. The spatial $T_G$ map at Gyeongju indicated seismic vulnerability of two- to five-storied buildings. In this study, the seismic zonation based on $T_G$ within the GIS-based GTIS was presented as regional efficient strategy for seismic hazard prediction and mitigation.

• Earthquakes and Structures
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• v.19 no.1
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• pp.1-16
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• 2020

This study presents an investigation of the dynamic interactions between a surface structure lying on two different soil deposits and a square-shaped buried structure embedded in the soil. To this end, a large number of numerical models are generated by using a well-known Finite Element Method software, i.e., OpenSEES. The interaction phenomenon is assumed to be affected by six different parameters. In the parametric study, these parameters are assumed to have various values in accordance with the engineering practices. A total of 1620 possible combinations of the parameter values are addressed in this study. 30 different numerical models are also generated as the 'free-field cases' to set a reference. The surface structure drift and acceleration amplifications are used as a measure to evaluate the dynamic interactions. The response (i.e., drifts and accelerations) amplifications are calculated as the ratio of the maximum surface structure response in any 'case' to the maximum surface structure response in corresponding free-field case. Variation of the response amplifications with any of the investigated parameters is addressed in this paper. The results obtained from the numerical analyses clearly reveal that the presence of a buried structure in the vicinity of a surface structure can cause both amplification and de-amplification of the surface structure responses, depending on the case parameters.

• Wind and Structures
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• v.12 no.2
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• pp.103-120
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• 2009

Articulated tower platforms due to its compliant nature are more susceptible to the dynamic effects of wind than conventional fixed platforms. Dynamic response analysis of a double hinged articulated tower excited by low frequency wind forces with random waves is presented in this paper. The exposed super structure of the platform, housing the drilling and production facilities is subjected to mean and fluctuating wind loads, while the submerged portion is acted upon by wind driven waves. The fluctuating component of the wind velocity is modeled by Emil Simiu's spectrum, while the sea state is characterized by Pierson-Moskowitz spectrum. Nonlinearities in the system due to drag force, added mass, variable submergence and instantaneous tower orientation are considered in the analysis. To account for these nonlinearities, an implicit time integration scheme (Newmark's-${\beta}$) has been employed which solves the equation of motion in an iterative fashion and response time histories are obtained. The power spectra obtained from random response time histories show the significance of low frequency responses.