• Advances in concrete construction
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• v.8 no.3
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• pp.165-172
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• 2019

Progressive collapse is one of the factors which if not predicted at the time of structure plan; its occurrence will lead to catastrophic damages. Through having a glance over important structures chronicles in the world, we will notice that the reason of their collapse is a minor damage in structure caused by an accident like a terrorist attack, smashing a vehicle, fire, gas explosion, construction flaws and its expanding. Progressive collapse includes expanding rudimentary rupture from one part to another which leads to total collapse of a structure or a major part it. This study examines the progressive collapse of a 5-story concrete building with three column eliminating scenarios, including the removal of the corner, side and middle columns with the ABAQUS software. Then the beams and the bottom of the concrete slab were reinforced by (reinforcement of carbon fiber reinforced polymer) FRP and then the structure was re-analyzed. The results of the analysis show that the reinforcement of carbon fiber reinforced polymer sheets is one of the effective ways to rehabilitate and reduce the progressive collapse in concrete structures.

• Journal of the Korean Society of Safety
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• v.33 no.6
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• pp.123-127
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• 2018

Recent catastrophic accidents at the underground subway stations in South Korea have proven that the subway evacuation is an important safety concern. Previous studies have used commercial programs for safety assessment or have been focused on development of computing algorithms rather than the basic analysis data which form the foundation of studies. In this study, we designed a new movement recording apparatus which measured and analyzed crowd movements including but not limited to moving velocity, specific flow rate and crowd density. Moreover, We propose new effective analysis method for evacuation studies with this apparatus.

• Fire Science and Engineering
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• v.33 no.5
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• pp.94-102
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• 2019

As the importance of first responses for fire accidents has grown in the safety management of nuclear power plants, a systematic approach to measure firefighters' psychological states and competence is needed. The current study investigated the construct of the risk perception of the firefighters working near nuclear power plant sites, and then developed and validated a new scale to measure firefighters' risk perception regarding nuclear power plant accidents. The scale items were developed on the basis of literature review and interviews with the firefighters working near nuclear power plant sites. In order to validate the new scale, we recruited 180 firefighters from five fire stations in the vicinity of the nuclear power plants in Jeonnam Province, Gyeongbuk Province, and Busan. The results of exploratory factor analyses revealed that the scale consisted of five factors: "manual" reflecting a lack of response guidelines and manuals for fire incidents and radioactive material release; "fear" reflecting a fear of fire incidents in the nuclear power plants and their catastrophic consequences; "resource" reflecting a lack of protective equipment and manpower for responding to fire incidents in the nuclear power plants; "trust" reflecting trust and cooperation with the counterpart institutions for firefighting in the nuclear power plants; and "knowledge" reflecting the knowledge of radioactivity and firefighting in the nuclear power plants. Further analyses provided statistical evidence supporting for the 15-item scale's internal consistency and construct validity. Finally, We discussed the implication and limitations of the current research.

• Fire Science and Engineering
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• v.27 no.6
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• pp.83-88
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• 2013

Catastrophic disasters are sprouting out recently, i.e., the radiation leaks and the hydrofluoric acid gas leaks, etc. The restoration work for these kinds of disasters is very harmful and dangerous for human beings to handle themselves, thus allowing manless robots to fly the reconnaissance planes over to the disaster stricken areas and do the necessary work instead. For this endeavor and purpose, we created and tested an intelligent robot that can inspect those areas, using Mbed (ARM processor) technology temperature sensors and gas sensors aided by CAM (Computer-Aided Manufacturing) cameras. Also, HTTP Server, PC, androids and their combined efforts allow their remote controlled operation from far away with timing control. These intelligent robots can be on duty for 24 hours, minimizing the accidents and crimes and what not, and can respond more quickly when these misfortunes actually happen. We can anticipate the economic effects as well, derived from the reduced needs for hiring human resources.

• Ocean Systems Engineering
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• v.8 no.1
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• pp.41-55
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• 2018

Accidental oil and gas leak is a critical concern for the offshore industry because it can lead to severe consequences and as a result, it is imperative to evaluate the probabilities of occurrence of the consequences of the leakage in order to assess the risk. Event Tree Analysis (ETA) is a technique to identify the consequences that can result from the occurrence of a hazardous event. The probability of occurrence of the consequences is evaluated by the ETA, based on the failure probabilities of the sequential events. Conventional ETA deals with events with crisp failure probabilities. In offshore applications, it is often difficult to arrive at a single probability measure due to lack of data or imprecision in data. In such a scenario, fuzzy set theory can be applied to handle imprecision and data uncertainty. This paper presents fuzzy ETA (FETA) methodology to compute the probability of the outcomes initiated due to oil/gas leak in an actual offshore-onshore installation. Post FETA, sensitivity analysis by Fuzzy Weighted Index (FWI) method is performed to find the event that has the maximum contribution to the severe sequences. It is found that events of 'ignition', spreading of fire to 'equipment' and 'other areas' are the highest contributors to the severe consequences, followed by failure of 'leak detection' and 'fire detection' and 'fire water not being effective'. It is also found that the frequency of severe consequences that are catastrophic in nature obtained by ETA is one order less than that obtained by FETA, thereby implying that in ETA, the uncertainty does not propagate through the event tree. The ranking of severe sequences based on their probability, however, are identical in both ETA and FETA.

• Fire Science and Engineering
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• v.32 no.6
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• pp.141-149
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• 2018

The perception of risk that firefighters have is closely related to their performance and emergency preparedness in nuclear power plant accidents. This study investigated the unique risk perception among firefighters working in nuclear power plants (NPPs) using a concept mapping method. Thirty three firefighters in NPPs participated in this study. Two core axes, "fear and control" and "coping resource", emerged in the firefighters' risk perception. In particular, the risk perception consisted of six clusters: fear of radiation exposure and low controllability; anxiety caused by the lack of control and authority; lack of trust and cooperation; lack of authority and professionals; lack of equipment, manual, and information; and lack of knowledge and training. Catastrophic expectation and a low sense of control caused by the lack of responsive resources were the main factors that increase the risk perception. The theoretical and practical contributions of this study were discussed.

• Journal of architectural history
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• v.15 no.2
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• pp.23-38
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• 2006

During the repair and restoration of the Daewoongjeon Hall of Youngguksa Temple, species identification and tree-ring dating for both present wood elements and charred ones excavated under the Hall, were conducted. The species of 74 wood elements of Daewoongjeon Hall, were identified as Pinus densiflora Sieb. et Zucc. and only 1 was identified as exotic Pinus species. The latter wood, which was used in the laths, seems to have been replaced during past repairs. Many documentary records and various artifacts pertaining to Youngguksa Temple are being excavated, but none described precisely the construction date of the present Daewoongjeon Hall. Also, from beneath the Daewoongjeon Hall, cornerstone and foundation of previous building and several charred wood elements were excavated. In comparing the direction of the stone columns of foundation of the previous structure and the existing Daewoongjeon Hall, the previous structure was rotated in an angle of approximately $15^{\circ}$. Therefore, in order to find the association of the previous structure with the present Daewoongjeon Hall, tree-ring dating was conducted. The dating of 41 original timbers and 14 roof-filling timbers of the present construction elements revealed that the last annual ring was of A. D. 1703 with complete latewood, indicating that those woods was cut some time between the autumn of 1703 and spring of 1704, and the building was erected in 1704 when we assume no period of wood storage. The year of the last annual ring of the charred elements, which were excavated from beneath the Daewoongjeon Hall, was analyzed as 1674. The cutting year of the woods used for the present building began in 1698, therefore, it can be presumed that the Daewoongjeon Hall before the fire was a structure that was elected shortly after 1674 and that a catastrophic fire occurred some time between 1674 and 1698.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.177-184
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• 2022

This study attempted to propose a plan to develop smart disaster prevention by applying the technologies of the 4th Industrial Revolution at each stage of disaster management to cope with the catastrophic situation of fire accidents. To this end, 150 disaster prevention experts and disaster prevention consumers were set as research subjects, and research data were collected and statistical analysis was conducted by distributing questionnaires. The main result was that disaster prevention experts and consumers commonly regarded the systematic factors of smart disaster prevention as the most important, and the difference in perception of the importance of each smart disaster prevention component was not statistically significant. Based on these results, this researcher suggested that in order for Korea's smart disaster prevention technology to develop, it is important for many researchers to research individual smart disaster prevention technologies, but above all, systematic R&D on how to manage, integrate them, and apply them in actual situations should be most preemptively.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.40-48
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• 2001

For a Liquified Petroleum Gas(LPG) station, the reliability analysis, such as Fussell-Vesely importance, risk decrease factor and risk increase factor, was carried out and the risk ranks of events were determined. In order to confirm the degree of the risks identified in the reliability analysis, the quantitative risk analysis was done for the equipments which had the large values of risk ranks. As a result of the importance analysis for the LPG station, the external event was identified as the most riskful event. The defect of construction structure and the pipe corrosion were riskful as well. The result of quantitative risk analysis showed that the length of 46.3 meters were estimated to damage the process equipments by the thermal flux from the catastrophic rupture of storage tank in Boiling Liquid Expanding Vapor Explosion.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.70-78
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• 2001

In order to find out which equipment failures were mostly contributed to the rupture of a continuous stirred tank reactor, the sensitivity analysis was carried out. The uncertainty of likelihood of the rupture of reactor was studied by the uncertainty analysis. And the cost effectiveness analysis resulted in the recommendation of the exchange with a better reliable unit if you want to maintain the process efficiently from the view point of cost. The uncertainty analysis showed that the likelihood of catastrophic rupture of the reactor was distributed from $8.09{\times}10^{-04}$ to $5.50{\times}10^{-02}/year$. As a result of cost-effectiveness analysis, it was proposed to exchange the voting logic unit for a better safer system.