• 제목/요약/키워드: Major Disaster

검색결과 597건 처리시간 0.024초

A wireless sensor with data-fusion algorithm for structural tilt measurement

  • Dan Li;Guangwei Zhang;Ziyang Su;Jian Zhang
    • Smart Structures and Systems
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    • 제31권3호
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    • pp.301-309
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    • 2023
  • Tilt is a key indicator of structural safety. Real-time monitoring of tilt responses helps to evaluate structural condition, enable cost-effective maintenance, and enhance lifetime resilience. This paper presents a prototype wireless sensing system for structural tilt measurement. Long range (LoRa) technology is adopted by the sensing system to offer long-range wireless communication with low power consumption. The sensor integrates a gyroscope and an accelerometer as the sensing module. Although tilt can be estimated from the gyroscope or the accelerometer measurements, these estimates suffer from either drift issue or high noise. To address this challenging issue and obtain more reliable tilt results, two sensor fusion algorithms, the complementary filter and the Kalman filter, are investigated to fully exploit the advantages of both gyroscope and accelerometer measurements. Numerical simulation is carried out to validate and compare the sensor fusion algorithms. Laboratory experiment is conducted on a simply supported beam under moving vehicle load to further investigate the performance of the proposed wireless tilt sensing system.

A Study on the Application of Smart Safety Technology at Construction Sites in South Korea

  • Choi, Ji-Sun;Hwang, Hoon-Hee;Ryu, Suzy
    • 국제학술발표논문집
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    • The 9th International Conference on Construction Engineering and Project Management
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    • pp.153-161
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    • 2022
  • Among all industries, the construction industry still remains a traditional one with low productivity due to its labor-intensive and field-dependent production system, its supplier-oriented industrial structure, and the disruption of the information flow between participants. In addition, the construction industry in South Korea has recently been required to transform itself according to social trends such as aging, the reduction of skilled workers, and the shortening of working hours, and the disaster and death rates in the industry, which are more than twice as high as those in other industries, are making it more necessary to solve chronic safety problems. Therefore, the purpose of this study is to grasp the actual condition of safety management on construction sites in South Korea and analyze cases of K-smart technology utilization for preventing safety accidents on construction sites. The study investigated and analyzed the following. First, construction sites in South Korea were analyzed by type of safety accident, by type of construction, and by construction contract amount. Second, the current status of accidents on small-sized construction sites with a high fatal accident rate and cases of safety accidents on construction sites were investigated. The results of the study are expected to contribute to the dissemination and spread of smart safety technology for not only identifying major factors in safety accidents that occur on construction sites but also preventing workers from suffering accidents.

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건축물 해체공사 안전 모니터링을 위한 3차원 자동변위계측 시스템 활용 방안 연구 (A Study on Applying 3D Automatic Displacement Measurement System for Safety Monitoring of Building Demolition Works)

  • 박한빈;한혜림;김태훈;조규만;조창근;김형기
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2022년도 가을 학술논문 발표대회
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    • pp.229-230
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    • 2022
  • According to the national building status, there are a total of 2.89 million buildings that are over 30 years old after completion, and the number is increasing by more than 70,000 to 80,000 buildings every year. As a result, the demand for demolition works is also increasing, and more than 3 to 4 collapse accidents occur steadily every year during demolition work. Major causes of accidents include non-compliance with plans, negligence of on-site supervisors, and failure to secure structural safety. Due to the strengthening of the Severe Disaster Punishment Act, there is growing interest in the demand for secure management of collapse detection during demolition works. Therefore, this study aims to investigate the applicability of real-time safety monitoring systems using a total station capable of 3D automatic displacement measurement in building demolition work for securing structural safety by the load changes during the demolition process.

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Damages to Rubble Stone Masonry Structures during the January 24, 2020, Sivrice (Elazığ) Earthquake in Turkey

  • Ural, Ali;Firat, Fatih K.;Kara, Mehmet E.;Celik, Tulin;Tanriverdi, Sukran
    • Earthquakes and Structures
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    • 제23권3호
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    • pp.231-243
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    • 2022
  • The earthquake with a magnitude of Mw 6.8, which occurred on January 24, 2020, hit Sivrice (Elazığ) province of Turkey. The earthquake area takes place on the East Anatolian Fault Zone (EAFZ) located between the Arabian and Turkish plates, one of the most active seismic regions in Turkey. According to the Disaster and Emergency Management Presidency of Turkey (AFAD), 584 buildings collapsed, 6845 were heavily damaged, 1207 were moderately damaged, and 14389 were slightly damaged. The authors went to the region of earthquake after the mainshock to investigate the earthquake performances of masonry buildings. This paper presents the seismological aspects of the earthquake, acceleration records, and response spectra with different damping ratios. Furthermore, some typical damages and failure mechanisms on masonry buildings like rubble stone dwellings and minarets are discussed with illustrative photos. Although many major earthquakes have occurred in the region, similar mistakes are still being made in masonry building construction. In consequence, some suggestions viewpoint of the wooden tie beams, the corner details of masonry walls, the door and window openings, the metal fasteners and the earthquake codes are made to be more careful in masonry constructions at the end of the article.

건설공사 발주 공공기관의 안전점검 체계구축에 관한 연구 (Establishment of a Safety Inspection System for Public Institutions Ordered Construction Projects)

  • 박응호;이수동;정기효
    • 대한안전경영과학회지
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    • 제25권3호
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    • pp.55-62
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    • 2023
  • Public institutions have a responsibility to ensure the safety of their employees and the public. One way to do this is to implement a systematic safety inspection system based on risk assessments and continuous improvements. This study developed a systematic safety inspection system for public institutions that are ordered construction projects. The proposed system in this study consists of a three-step process: (1) developing safety grade evaluation tables, (2) preparing and conducting safety inspections, and (3) evaluating and improving safety management grades. The first step is to develop safety grade evaluation tables by analysis and diagnosis of the construction site's work type, disaster statistics, and related laws. The second step is to conduct safety inspections using the developed evaluation tables. The third step is to determine the safety management grade based on the results of the safety inspection, and to improve risk factors found during the safety evaluation. The proposed system was implemented in highway construction projects carried out by public institutions. The results showed that the proposed system has two major effects: (1) reducing accident-related deaths and injuries, (2) improving safety management levels by continuous evaluation and improvement. The proposed system can be utilized in construction projects ordered by public institutions to improve the level of occupational safety and health.

Multihazard capacity optimization of an NPP using a multi-objective genetic algorithm and sampling-based PSA

  • Eujeong Choi;Shinyoung Kwag;Daegi Hahm
    • Nuclear Engineering and Technology
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    • 제56권2호
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    • pp.644-654
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    • 2024
  • After the Tohoku earthquake and tsunami (Japan, 2011), regulatory efforts to mitigate external hazards have increased both the safety requirements and the total capital cost of nuclear power plants (NPPs). In these circumstances, identifying not only disaster robustness but also cost-effective capacity setting of NPPs has become one of the most important tasks for the nuclear power industry. A few studies have been performed to relocate the seismic capacity of NPPs, yet the effects of multiple hazards have not been accounted for in NPP capacity optimization. The major challenges in extending this problem to the multihazard dimension are (1) the high computational costs for both multihazard risk quantification and system-level optimization and (2) the lack of capital cost databases of NPPs. To resolve these issues, this paper proposes an effective method that identifies the optimal multihazard capacity of NPPs using a multi-objective genetic algorithm and the two-stage direct quantification of fault trees using Monte Carlo simulation method, called the two-stage DQFM. Also, a capacity-based indirect capital cost measure is proposed. Such a proposed method enables NPP to achieve safety and cost-effectiveness against multi-hazard simultaneously within the computationally efficient platform. The proposed multihazard capacity optimization framework is demonstrated and tested with an earthquake-tsunami example.

Revision and catagorization of evaluation criteria for state change factors in agricultural reservoirs

  • Jae Woong Shim;Young Hak Lee;Dal Won Lee
    • 농업과학연구
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    • 제49권4호
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    • pp.707-717
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    • 2022
  • As the variability of recent rainfall is increasing, it is becoming important to recognize the possibility of changes in the current reservoir state in advance and to inspect the stability based on accurate evaluation standards. However, the evaluation standards for the state change factors of reservoirs are still not suitable for agricultural reservoirs and thus much improvement is needed. Therefore, in this study, the evaluation criteria for state change factors specialized for small reservoirs were categorized and standards were prepared by considering factors that may cause state changes on the dam crest, upstream slope, and downstream slope of the embankment. The categorized results were configured based on the number of mentions of the precision safety inspection report on major defects in 102 reservoirs and the defect factors found in field investigations. The findings of the study indicated that the current state change standards require many revisions for excessive or unnecessary state change factors in the reservoir. Specifically, the deletion of measurement gauges not applicable to the reservoir, the addition of defects found in the reservoir, and the scope of use of the term were proposed. The results of this study can contribute to efficient system operation and management by improving the deficiencies in the system and introducing a new state change factor.

Flexural performances of deep-deck plate slabs: Experimental and numerical approaches

  • Inwook Heo;Sun-Jin Han;Khaliunaa Darkhanbat;Seung-Ho Choi;Sung Bae Kim;Kang Su Kim
    • Steel and Composite Structures
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    • 제52권3호
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    • pp.313-325
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    • 2024
  • This work presents experimental and numerical investigations on the flexural performances of composite deep-deck plate slabs. Seven deep-deck plate slab specimens with topping concrete were fabricated; the height of the topping slab as well as presence and type of shear connector were set as the main variables to perform bending experiments. The flexural behaviors of the specimens and composite behaviors of the deck plate and concrete were analyzed in detail. The contributions of the deck plate to the flexural stiffness and strength of the slab were identified through finite element (FE) analysis. FE analysis was carried out using the validated FE model by considering the varying bond strengths of the deck plates and concrete, thickness of the deck plate, and types and spacings of the shear connectors. Based on the results, the degree of composite of the deep-deck plate was examined, and a flexural strength equation for the composite deck plate slabs was proposed.

미세먼지 저감을 위한 그린인프라 계획요소 도출 - 텍스트 마이닝을 활용하여 - (Derivation of Green Infrastructure Planning Factors for Reducing Particulate Matter - Using Text Mining -)

  • 석영선;송기환;한효주;이정아
    • 한국조경학회지
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    • 제49권5호
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    • pp.79-96
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    • 2021
  • 그린인프라 계획은 미세먼지 저감을 위한 대표적인 조경 계획 방안 중 하나이다. 이에, 본 연구에서는 미세먼지 저감을 위한 그린인프라 계획 시 활용될 수 있는 요소를 텍스트 마이닝 기법을 활용하여 도출하고자 하였다. 미세먼지 저감계획, 그린인프라 계획 요소 등의 키워드를 중심으로 관련 선행연구, 정책보고서 및 법률 등을 수집하여 텍스트 마이닝을 통해 단어 빈도-역 문서 빈도(Term Frequency-Inverse Document Frequency, 이하 TF-IDF) 분석, 중심성 분석, 연관어 분석, 토픽 모델링 분석을 실시하였다. 연구결과, 첫째, TF-IDF 분석을 통해 미세먼지 및 그린인프라와 관련된 주요 주제어는 크게 환경문제(미세먼지, 환경, 탄소, 대기 등), 대상 공간(도시, 공원, 지역, 녹지 등), 그리고 적용 방법(분석, 계획, 평가, 개발, 생태적 측면, 정책적 관리, 기술, 리질리언스 등)으로 구분할 수 있었다. 둘째, 중심성 분석 결과, TF-IDF와 유사한 결과가 도출되었으며, 주요 키워드들을 연결하는 중심단어는 '그린뉴딜', '유휴부지'임을 확인할 수 있었다. 셋째, 연관어 분석 결과, 미세먼지 저감을 위한 그린인프라 계획 시, 숲과 바람길의 계획이 필요하며, 미기후 조절의 측면에서 수분에 대한 고려가 반드시 필요한 것으로 확인되었다. 또한, 유휴공간의 활용 및 혼효림의 조성, 미세먼지 저감 기술의 도입과 시스템의 이해가 그린인프라 계획 시 중요한 요소가 될 수 있음을 확인할 수 있었다. 넷째, 토픽 모델링 분석을 통해 그린인프라의 계획요소를 생태적·기술적·사회적 기능을 중심으로 분류하였다. 생태적 기능의 계획요소는 그린인프라의 형태적 부분(도시림, 녹지, 벽면녹화 등)과 기능적 부분(기후 조절, 탄소저장 및 흡수, 야생동물의 서식처와 생물 다양성 제공 등), 기술적 기능의 계획요소는 그린인프라의 방재 기능, 완충 효과, 우수관리 및 수질정화, 에너지 저감 등, 사회적 기능의 계획요소는 지역사회 커뮤니티 기능, 이용객의 건강성 회복, 경관 향상 등의 기능으로 분류되었다. 이와 같은 결과는 미세먼지 저감을 위한 그린인프라 계획 시 리질리언스 및 지속가능성과 같은 개념적 키워드 중심의 접근이 필요하며, 특히, 미세먼지 노출 저감의 측면에서 그린인프라 계획요소의 적용이 필요함을 시사한다고 볼 수 있다.

동해 서남해역에서 여름철 $^{234}Th/^{238}U$ 비평형을 이용한 입자상 유기탄소 침강플럭스 추정 (Estimate of Particulate Organic Carbon Export Flux Using $^{234}Th/^{238}U$ Disequilibrium in the Southwestern East Sea During Summer)

  • 김동선;최만식;오혜영;김경희;노재훈
    • 한국해양학회지:바다
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    • 제14권1호
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    • pp.1-9
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    • 2009
  • 2007년 8월에 동해에서 처음으로 $^{234}Th/^{238}U$ 비평형(disequilibrium)을 이용하여 유광대에서 심층으로의 입자상 유기탄소 침강플럭스(export flux)를 추정하였다. 입자상 유기탄소 침강플럭스는 $^{234}Th$ 침강 플럭스에 POC/$^{234}Th_p$ 비율을 곱하여 구하였으며, $^{234}Th$ 플럭스는 표층에서 수심 100 m까지 $^{234}Th/^{238}U$ 비평형을 적분하여 계산하였고 POC/$^{234}Th_p$ 비율은 수심 150 m와 200 m에서 채집한 부유물질 시료(입자크기가 0.7 ${\mu}m$이상)에서 측정하였다. 유기탄소 침강플럭스는 14-506 mg C $m^{-2}$ $day^{-1}$의 범위를 나타냈으며, 정점 A2에서 최고값을 보였고 정점 D4에서 최소값을 보였다. 유기탄소 침강플럭스는 유광대에서의 일차생산력과 매우 좋은 상관관계를 나타내었으며, 유기탄소 침강플럭스/일차생산력 비율은 0.29-0.62(평균 0.43)의 범위를 보였고, 연안역에 비해 심해역에서 다소 높은 비율을 나타냈다. 동해에서 관측한 유기탄소 침강플럭스는 전반적으로 대양에서 관측한 값들보다는 높았고 대륙 주변해에서 관측한 값보다 다소 높거나 유사하였다. 동해에서의 침강플럭스/일차생산력 비율은 북해(North Sea)와 척치해(Chukchi Sea)에서 관측한 값들과는 유사하였지만, 라브라도해(Labrador Sea), 바렌츠해(Barents Sea), 리온스만(Gulf of Lions)에서 관측한 값들보다는 월등히 높았다. 따라서 동해는 전세계 해역에서 유광대에서 생성된 유기탄소가 수심 200 m 이하 심층으로 가장 많은 비율로 침강하는 해역들 가운데 하나라고 생각된다.