• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.138-147
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• 2018

The network analysis is done to explore what kind if issues are diffused about earthquake and the role of social media. The types of disaster information is classified into formal and informal. The role of actor is classified based on the concentrativeness and the diffusion of issue. Youttube is functioned as a formal channel and an informal channel when disaster happened. In case of government's video, issue contractiveness is high but the diffusion is low. In case of media's video, issue contractiveness and the diffusion are all high. In case of individual channel, issue contractiveness is low, but diffusion is high. In disaster, youtube is a tool to respread the disaster issue. Government needs to try diffusion of government's news actively in disaster.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.97-106
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• 1993

In order to provide informations for the earth's deep interior and the earthquake mechanism, we have been operating the three components of Streckeisen Seismometers at Pohang Observatory, Korea, as a part of a long period seismic network (POSEIDON) in the northwestern Pacific now under construction. The recording system is specially designed to be able to obtain outputs of broad band and wide dynamic range; BRB (Broad Band), LP (Long Period), and VLP (Very Long Period) output. The triggered BRB and LP signals are digitized with the sampling intervals of 0.1 and 0.4 second, respectively. The lowpass filtered VLP output is digitized and recorded contineously with the sampling interval of 10 seconds. About 120 regional and teleseismic events have been successfully recorded for one and half year since late March, 1991. As a preliminary study, eight events of them are analyzed to determine Rayleigh wave dispersion curves in the period range of 20 to 300 seconds for the continental and oceanic paths. The curves are compared with the typical continental and oceanic ones to discuss the earth's deep interior.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.55-63
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• 2020

In this study, a scaled model test of the shaking table and a seismic analysis considering effective stresses were performed to reveal the dynamic behavior characteristics of box structures deep located in multi-layered soils upon seismic loading. The input seismic wave was operated below the ground using five seismic waves, including long period wave (Hachinohe), short period wave (Ofunato), artificial wave and real earthquakes that occurred in Gyeong-ju and Po-hang. As a result of model test and numerical analysis, the vertical displacement of box structures upon seismic loading was greater than that of horizontal direction, and it was confirmed that an increase of excess pore water pressure below the foundation ground caused a displacement. In addition, behavior of the ground and structures during artificial seismic wave appeared to be larger than real earthquake wave.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.559-569
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• 2022

This study investigated the acidification and mixing with seawater of groundwater, stream water, and reservoir water in the Hunghae area of Pohang City, as well as the source of water expelled to the stream by liquefaction induced by the Pohang earthquake on 15 November 2017. Geologically, the area consists of Tertiary sedimentary rocks. We collected six samples of groundwater, five of reservoir water, four of stream water, two of liquefaction water, and one of seawater to analyze the chemical composition and stable isotopes (𝛿D and 𝛿¹⁸O). Gogkang Stream flows eastward through the central part of the study area into the East Sea. The groundwater and reservoir water in the lower part of the stream are acidic (pH < 4), have a Ca(Mg)-SO₄ composition, and high concentrations of Al, Fe, and Mn, likely due to the oxidation of pyrite in Tertiary rocks. The groundwater in the upper part of the stream have a Ca(Na)-HCO₃(Cl) composition, indicating the mixing of seawater with the stream water. The 𝛿D and 𝛿¹⁸O isotope data indicate the isotopic enrichment of reservoir water by evaporation. Based on the chemical and isotopic data, it is inferred that the two samples of liquefaction water originated from alluvium water in a transition zone with stream water, and from deep and shallow groundwaters that has been infiltrated by seawater, respectively.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.199-201
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• 2019

최근 경주 포항 지역에 지진피해 등 대구 경북권의 잦은 재난 발생으로 인해 증대되고 있는 노후학교 건축물의 안전성 위험 문제에 대한 선제 대응이 필요한 상황이 요구되고 있다. 학교 건축물에 건물의 위험도를 파악할 수 있는 센서들을 부착하고, 실시간 모니터링을 통해 건물의 구조적 위험성을 판단한다. 건물의 위험도가 심각한 단계에 이르면 스마트폰(Smart Phone) 앱(Application)과 음성안내방송을 통해 건물의 재실자와 관리자에게 즉시 경보를 발령하며, 대피할 수 있도록 가이드를 제시 한다. 이에 본 논문에서는 스마트 재난경보방송을 위한 스마트폰 애플리케이션(application)을 통해 재난 상황을 전파하고 대응할 수 있게 건물의 위험성 발생 위치정보를 제공하며 대피 안내 정보를 제공한다. 동시에 건물의 구내방송 시스템과 연계를 통해 음성 안내방송을 자동으로 수행하며, 두 가지 방식으로 재난 메시지를 전파하여 중복성을 가지고 경보 전파를 수행한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.94-101
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• 2021

According to the Facility Management System (FMS) operated by the Korea Authority of Land & Infrastructure Safety, it is expected that the number of aging facilities that have been in use for more than 30 years will increase rapidly to 13.9% in 2019 and 34.5% in 2929, and end up with a social problem. In addition, with the revision of "Common Application of Seismic Design Criteria" by the Ministry of Public Administration and Security in 2017, it is mandatory to re-evaluate all existing road facilities and if necessary seismic reinforcement should be done to minimize the magnitude of earthquake damage and perform normal road functions. The seismic performance management-decision support technology currently used in seismic performance management practice in Korea only determines the earthquake-resistance reinforcement priority based on the qualitative index value for the seismic performance of individual facilities. However with this practice, normal traffic functions cannot be guaranteed. A new seismic performance management decision support technology that can provide various judgment data required for decision making is needed to overcome these shortcomings and better perform seismic performance management from a road network perspective.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.86-93
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• 2020

The demand for maintenance in Korea infrastructure facilities constructed since the 1970s has increased significantly compared to the demand for new construction. Moreover, after the Gyeongju and Pohang earthquakes, seismic performance evaluation, repair, and retrofitting projects have been carried out. Therefore, in this study, a specimen was designed following the L-type GFRP Plate Externally Bonded Retrofit method, one among other retrofit methods. The L-type GFRP Plate was bonded to the specimen by epoxy and a washered steel nail. A four-point bending test was performed to confirm the strengthening effect of the Externally Bonded Retrofit method using an L-type GFRP Plate. The strengthening effect of the L-type GFRP plate was proven experimentally, and the behavior of the beam designed following the L-type GFRP Plate Externally Bonded Retrofit method was evaluated according to Korea's "Design Manual & Specification for Strengthening of RC Structures by Advanced Composites System". Furthermore, the effectiveness of the bonding method, a combination of epoxy and washered steel nail, was also checked. The results showed that the design, according to the guidelines mentioned above, predicted the strength of the member well, but the failure mode did not satisfy the design assumption because of unexpected damage to the GFRP plate due to the fixing method, washered steel nail.

• Economic and Environmental Geology
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• v.31 no.1
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• pp.21-29
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• 1998

Broadband receiver functions are developed from teleseismic P waveforms recorded at Wonju (KSRS), Inchon (IRIS), and Pohang (PHN), and are analyzed to examine the crustal structure beneath the three stations. The teleseismic receiver functions are inverted in the time domain to the vertical P wave velocity structure beneath the stations. Clear P-to-S converted phases from the Moho interface are observed in teleseismic seismograms recorded at the three stations. We estimated the crustal velocity structures beneath the stations using the receiver function inversion. The general features of inversion results are as follows: (1) For Pohang station, there is a high velocity gradient at a 4~5 km deep for SE and NW back azimuth and a low velocity zone at around 10 km deep. The Moho depth is 28 km for NW direction. (2) The shallow crustal structure beneath Wonju station is somewhat complex and there is a high-velocity zone ($V_p{\simeq}6.8km/sec$) at 3 to 4 km deep. The average crustal thickness is 33 km, and a transition zone exists at a 30~33 km deep of lower crust, of which velocity is abruptly changed 6.4 to 7.9 km/sec. (3) For Inchon station, the crustal velocity gradient monotonously increases up to the Moho discontinuity and the velocity is abruptly changed from 6.2 km/sec to 7.9 km/sec at 29 km deep.

• Journal of the Korea Institute of Building Construction
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• v.24 no.1
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• pp.55-66
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• 2024

This research addresses the types and causes of defects in seismic retrofitting projects of school facilities, which, following the Gyeongju and Pohang earthquakes in September 2016 and November 2017 respectively, have been identified as having comparatively lower seismic resilience among public buildings. The incidence of seismic retrofitting has notably increased in the subsequent years, raising concerns about the potential for defects arising from these efforts. The government has committed to enhancing the seismic resilience of all public facilities by 2035, with a specific focus on completing upgrades for educational establishments by 2029. Although prior investigations have explored construction defects in school facilities, there exists a gap in research specifically targeting defects within seismic retrofitting processes. Thus, this study aims to catalog the defects associated with seismic retrofitting efforts and analyze their underlying causes to identify crucial management strategies for defect mitigation. Furthermore, by examining the interplay between defect types and their causative factors, the study seeks to pinpoint essential management practices that could preempt defects during the construction phase, ultimately aiding in the reduction of future maintenance expenditures.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.21-33
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• 2020

Ground response analysis has been conducted for each borehole data in Pohang area, using 1D equivalent linear method program, to investigate the applicability of amplification factor to estimate peak ground acceleration. Earthquake motions for ground response analysis were prepared by matching response spectrums for return period of 500, 1000, and 2400 years suggested by seismic design code (MOIS, 2017). Ground survey data were acquired from Geotechnical Information DB System. It has been confirmed that response spectrum obtained from ground response analysis showed good agreement with those from seismic design code irrespective of ground classification. However, PGA (Peak Ground Accelerations) of ground response analysis did not coincide with PGA calculated using amplification factor suggested by seismic design code.