• Title/Summary/Keyword: Time of Collapse

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Enhancing the Blast Resistance of Structures Using HPFRCC, Segmented Composites, and FRP Composites (HPFRCC, 분절 복합체 및 FRP를 활용한 구조물의 내폭 성능 향상)

  • Yoon, Young-Soo;Yang, Jun-Mo;Min, Kyung-Hwan;Shin, Hyun-Oh
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.745-748
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    • 2008
  • The past structures were just required bearing capacity to service load, serviceability, and resistance to corrosion. However this point of view has changed after 9.11 terrorism, capacities which can bear impact loading by explosion, and heat by fire happening at the same time, become to be important as a basic condition. The blast resistance capacity of structures is very important part against all over the world is intimidated by terrorism everyday in current point of time. The target of this research is a development of segmented composites and layered structures with high blast resistance using cementitious composites, concrete and FRP composites, which has high tensile strength and ductility, to apply in not only existing facilities but also new ones. Through the improvement of blast resistance, casualties and economic loss can be minimized, and it is possible to diminish the structure collapse and delay the time of structure collapse by thermal effect, impact loading, dynamic loading and high strain.

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Uncertainties impact on the major FOMs for severe accidents in CANDU 6 nuclear power plant

  • R.M. Nistor-Vlad;D. Dupleac;G.L. Pavel
    • Nuclear Engineering and Technology
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    • v.55 no.7
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    • pp.2670-2677
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    • 2023
  • In the nuclear safety studies, a new trend refers to the evaluation of uncertainties as a mandatory component of best-estimate safety analysis which is a modern and technically consistent approach being known as BEPU (Best Estimate Plus Uncertainty). The major objectives of this study consist in performing a study of uncertainties/sensitivities of the major analysis results for a generic CANDU 6 Nuclear Power Plant during Station Blackout (SBO) progression to understand and characterize the sources of uncertainties and their effects on the key figure-of-merits (FOMs) predictions in severe accidents (SA). The FOMs of interest are hydrogen mass generation and event timings such as the first fuel channel failure time, beginning of the core disassembly time, core collapse time and calandria vessel failure time. The outcomes of the study, will allow an improvement of capabilities and expertise to perform uncertainty and sensitivity analysis with severe accident codes for CANDU 6 Nuclear Power Plant.

A Study on the System for measuring the Activity of Honeybees inside and outside the Beehive

  • Kim, Joon Ho;Han, Wook;Chung, Wonki;Mo, Changyeon;Han, Xiongzhe;Kim, Subae
    • International Journal of Advanced Culture Technology
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    • v.10 no.4
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    • pp.511-517
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    • 2022
  • Recently, due to rapid climate change, the population of honey bees has decreased, posing a great threat to the existence of the Earth's ecosystem. In particular, the colony collapse phenomenon in which bees disappeared nationwide in early 2022 had devastating consequences for beekeepers. In order to solve the problems of beekeeping due to climate change, it is urgent to develop a system that can monitor the situation inside the hive through various IoT sensors. This paper develops a system that can measure the activity of bees inside the hive and uses it to measure the number of times of entry and exit of the hive. The data measured by the developed system can be monitored in real time on a smartphone through the cloud server. The system developed in this paper can monitor the ecology of bees according to climate change and measure internal and external bee activities. Using this method, it is possible to check in advance for the colony collapse phenomenon in which bees disappeared in early 2022. This is very meaningful in that it presents an alternative that can identify the cause of the problem through early detection.

Seismic demand assessment of semi-rigid steel frames at different performance points

  • Sharma, Vijay;Shrimali, Mahendra K.;Bharti, Shiv D.;Datta, Tushar K.
    • Steel and Composite Structures
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    • v.41 no.5
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    • pp.713-730
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    • 2021
  • The seismic performance of rigid steel frames is widely investigated, but that of semi-rigid (SR) steel frames are not studied extensively, especially for near-field earthquakes. In this paper, the performances of five and ten-story steel SR frames having different degrees of semi-rigidity are evaluated at four performance points in the four different deformation states, namely, the elastic, elasto-plastic, plastic, and near collapse states. The performances of the SR frames are measured by the response parameters including the maximum values of the top floor displacement, base shear, inter-story drift ratio, number of plastic hinges, and SRSS of plastic hinge rotations. These response parameters are obtained by the capacity spectrum method (CSM) using pushover analysis. The validity of the response parameters determined by the CSM is evaluated by the results of the nonlinear time history analysis (NLTHA) for both near and far-field earthquakes at different PGA levels, which are consistent with the performance points. Results of the study show that the plastic hinges of SR frame significantly increase in the range of plastic to near-collapse states for both near and far-field earthquakes. The effect of the degree of semi-rigidity is pronounced only at higher degrees of semi-rigidity. The predictions of the CSM are fairly well in comparison to the NLTHA.

Methodology for investigating the behavior of reinforced concrete structures subjected to post earthquake fire

  • Behnam, Behrouz;Ronagh, Hamid R.;Baji, Hassan
    • Advances in concrete construction
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    • v.1 no.1
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    • pp.29-44
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    • 2013
  • Post earthquake fire (PEF) can lead to the collapse of buildings that are partially damaged in a prior ground-motion that occurred immediately before the fire. The majority of standards and codes for the design of structures against earthquake ignore the possibility of PEF and thus buildings designed with those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the Life-Safety performance level of structures designed to the ACI 318-08 code after they are subjected to two different earthquake levels with PGA of 0.35 g and 0.25 g. This is followed by a four-hour fire analysis of the weakened structure, from which the time it takes for the weakened structure to collapse is calculated. As a benchmark, the fire analysis is also performed for undamaged structure and before occurrence of earthquake. The results show that the vulnerability of structures increases dramatically when a previously damaged structure is exposed to PEF. The results also show the damaging effects of post earthquake fire are exacerbated when initiated from second and third floor. Whilst the investigation is for a certain class of structures (regular building, intermediate reinforced structure, 3 stories), the results confirm the need for the incorporation of post earthquake fire in the process of analysis and design and provides some quantitative measures on the level of associated effects.

The Study of Hyper-Reality in Editorial Fashion Photographs - Focused on Vogue Magazine since 2000 - (에디토리얼 패션 사진에 표현된 하이퍼 리얼리티 표현 연구 - 2000년도 이후 Vogue지를 중심으로 -)

  • Yang, Sook-Hi;Yun, Young
    • The Research Journal of the Costume Culture
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    • v.18 no.6
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    • pp.1261-1273
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    • 2010
  • The advent of various arts and remarkable development of mass media since 1980s accelerate fashion photographs' advancement. The expression of fashion through photographs can represent characteristics of ages, societies, cultures, traits of designers and techniques of photographers. In addition, that is the tool which contains economical role as a product and artistic role as photos. Therefore, this study examines hyprt-reality images in editorial fashion photographs. Hyper-reality means the reproduction which represents the reality of life more actually. Hyper-reality through photographs elevates reality of virtual things and creates the confused situation which haunts the boundary between reality and reproduction. This study classifies the hyper-reality in editorial fashion photographs into three groups by their external traits, ideal reality, collapse of reality, and restoration of reality. First, ideal reality is represented as harmony among fashion, characters, and space, causality of fashion with time and circumstances, positive will, and melting with nature. Second, collapse of reality is expressed as in harmony between fashion and situation, violence, fetishism and symbol of death. Third, restoration of reality is shown as recurrence to nature and images of utopia to express dignity of life.

A Study on the Strength Properties of FRP Member for Making Personal Disaster Shelters in Rural Area (농산촌 재난대피시설 제작을 위한 FRP 부재의 강도특성에 관한 연구)

  • Kim, Jung Meyon;Hwang, Dea Won;Lim, Hyun Taek;Park, Sung Yong;Yeon, Kyu Seok;Kim, Yong Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.58 no.2
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    • pp.73-82
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    • 2016
  • This study is about development of personal disaster shelters for minimization of the casualties caused by the landslide and steep slope collapse. The objectives of present research is the selection of disaster evacuation facilities utilizing FRP (Fiber Reinforced Plastic) material. For the proper assessment of FRP member, several layers by strength test and the three-dimensional numerical analysis of these FRR member was carried out. As a result, the personal disaster evacuation facility utilizing FRP materials, was found to be of a material that is able to protect the weak person at the time of the collapse of the landslides and steep slopes.

A Study on behavior of Slope Failure Using Field Excavation Experiment (현장 굴착 실험을 통한 사면붕괴 거동 연구)

  • Park, Sung-Yong;Jung, Hee-Don;Kim, Young-Ju;Kim, Yong-Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.59 no.5
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    • pp.101-108
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    • 2017
  • Recently, the occurrence of landslides has been increasing over the years due to the extreme weather event. Developments of landslides monitoring technology that reduce damage caused by landslide are urgently needed. Therefore, in this study, a strain ratio sensor was developed to predict the ground behavior during the slope failure, and the change in surface ground displacement was observed as slope failed on the field model experiment. As a result, in the slope failure, the ground displacement process increases the risk of collapse as the inverse displacement approaches zero. It is closely related to the prediction of precursor. In all cases, increase in displacement and reverse speed of inverse displacement with time was observed during the slope failure, and it is very important event for monitoring collapse phenomenon of risky slopes. In the future, it can be used as disaster prevention technology to contribute in reduction of landslide damage and activation of measurement industry.

The study on the safety inspection system model of the tower crane a construction site in Korea (국내 건설현장 타워크레인 안전진단 관리시스템 모델에 관한 연구)

  • Yeon, In-Soo;Seo, Jang-Hoon;Kang, Kyeong-Sik
    • Proceedings of the Safety Management and Science Conference
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    • 2006.11a
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    • pp.499-507
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    • 2006
  • The tower cranes are widely used in very useful construction machine the sites of constructing high-structure and have a structural sensitiveness. Therefore, the accidents have often happened due to the deficiency of laborer's understanding md lack of safety of structure. Till now, as we have research and studied above, we can properly protect accidents by construction equipments particularly crane as well as most disasters which occur frequently in construction site. The goal of this study is the safety inspection model of the tower crane a construction site, which preventible the collapse accident of tower crane which is constructed by using the correcting frame. In order to accomplish the goal of this study, the field survey, the reference investigation and the structure analysis were performed for the collapse accident of tower nine using the correcting data. This study will be proposed a build-up solutions about operating and release of safety constructions and researched about software safety estimation. Also, preventing safety problems of Tower Crane Construction site as applying safety estimation program and laws and regulations. As a result, The real time control of tower crane inspection system is implemented by to illustrate the application of the adopted optimal design model.

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A Study on the Safety Inspection System Model of The Tower Crane a Construction Site in Korea (국내 건설현장 타워크레인 안전진단 관리시스템 모델에 관한 연구)

  • Yoon, In-Soo;Kang, Kyung-Sik
    • Journal of the Korea Safety Management & Science
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    • v.9 no.1
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    • pp.37-49
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    • 2007
  • The tower cranes are widely used in very useful construction machine the sites of constructing high-structure and have a structural sensitiveness. Therefore, the accidents have often happened due to the deficiency of laborer's understanding and lack of safety of structure. Till now, as we have research and studied above, we can properly protect accidents by construction equipments particularly crane as well as most disasters which occur frequently in construction site. The goal of this study is the safety inspection model of the tower crane a construction site, which preventible the collapse accident of tower crane which is constructed by using the correcting frame. In order to accomplish the goal of this study, the field survey, the reference investigation and the structure analysis were performed for the collapse accident of tower crane using the correcting data. This study will be proposed a build-up solutions about operating and release of safety constructions and researched about software safety estimation. Also, preventing safety problems of Tower Crane Construction site as applying safety estimation program and laws and regulations. As a result, The real time control of tower crane inspection system is implemented by to illustrate the application of the adopted optimal design model.