• Title/Summary/Keyword: initial fire behavior

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Service Design for Using the Drones in the Early Stages Fires of Dense Residential Areas (주택가 밀집지역 화재발생 초기 드론 활용 서비스디자인 연구)

  • Youn, Gyo-Hee
    • The Journal of the Korea Contents Association
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    • v.19 no.11
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    • pp.111-121
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    • 2019
  • Recently, through the services that use drones at fire sites to deliver on-site and road conditions into the situation room and life-saving activities or the deliveries of first aid outfits at the accident scenes that are inaccessible to humans, there are more and more cases of dealing with emergency situations. Therefore, by studying the service design using drones in the initial stage of response to fires in dense residential areas, this study was intended to reify the service design area of the response stage, including the dispatch of fire sites and the fire suppression. To do this, through literature researches, research directions were explored by examining the concept and process review of service design, and by analyzing the application cases using service design. In order examine the validity of this study, a one-on-one interview was conducted to identify the use and problems of drones among incumbent firefighters, and identified the applicability of drones to fire sites by targeting drone experts. Field research was conducted to identify the location and distance of road conditions, site conditions, and 119 safety centers, by making Yongsan-gu, the most vulnerable area to fire in Seoul, as a research sample. And, among the methodologies of service design, Persona and Customer Journey Map were prepared and Insight was derived, by using virtual scenarios for the experience values and behavior analyses of the interested parties. Through these processes, this researcher intended to present the fire-response service design and help establish the direction of service design in the initial stages of fire in Korea.

A Study on Rotation Behavior of High Strength Steel Endplate Connections under Fire (화재시 고강도강 엔드플레이트 접합부의 회전 거동에 관한 연구)

  • Shin, Su-Min;Lee, Chy-Hyoung;Yoon, Sung-Kee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.5
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    • pp.35-43
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    • 2016
  • In order to understand rotation behavior of high strength steel endplate connections under fire, this study is compared with existing studies conducted using FEA program. Eurocode 3 presents the three failure modes according to the prediction of bending resistance moment. The parameters of analysis model are temperature, thickness and steel materials of endplate. The rotation stiffness, and bending resistance moment are analyzed according to the parameters. The change of rotation stiffness and bending resistance moment are analyzed about the parameters, regression equations are suggested the change of high strength steel endplate connections. Consequently, the regression equations were proposed as the linear and quadratic equation. The moment ratio of high strength steel under fire was more reduced than the carbon steel, and was small effect about the thickness. When the high strength steel under fire was compared with at ambient temperature, the slope of initial rotation stiffness reduced, the increment ratio of moment was slow, and the change of plastic rotation stiffness wasn't effect by the thickness increase.

A Numerical Study on Smoke Behavior of Fishing Vessel Engine Room (어선 기관실의 연기 거동에 관한 수치해석 연구)

  • JANG, Ho-Sung;JI, Sang-Won
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.5
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    • pp.683-690
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    • 2021
  • The ventilation system of the engine room of a ship is generally installed to supply the combustion air necessary for the internal combustion engine and to remove the heat source generated in the engine room, and it must satisfy the international standard (ISO 8861) for the design conditions and calculation standards for the ventilation of the ship engine room. The response delay of the ventilation system including the fire detector is affected by the airflow formed inside the area and the location of the fire detector. In this study, to improve the initial fire detection response speed of a fire detector installed on a fishing vessel and to maintain the sensitivity of the installed detector, the smoke behavior was simulated using the air flow field inside the engine room, the amount of combustion air in the internal combustion engine, and the internal pressure of the engine room as variables. Analysis of the simulation results showed that reducing the flow rate in the air flow field and increasing the vortex by reducing the internal pressure of the engine room and installing a smoke curtain would accelerate the rise of the ceiling of the smoke component and improve the smoke detector response speed and ventilation system.

Nonlinear Analysis Models to Predict the Hysteretic Behavior of Existing RC Column Members (기존 RC 기둥 부재의 이력거동 예측을 위한 비선형 해석모델)

  • Choi, Myeong-Ho;Lee, Chang-Hwan
    • Journal of Korean Association for Spatial Structures
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    • v.22 no.4
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    • pp.89-98
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    • 2022
  • The recent earthquake in Korea caused a lot of damage to reinforced concrete (RC) columns with non-seismic details. The nonlinear analysis enables predicting the hysteresis behavior of RC columns under earthquakes, but the analytical model used for the columns must be accurate and practical. This paper studied the nonlinear analysis models built into a commercial structural analysis program for the existing RC columns. The load-displacement relationships, maximum strength, initial stiffness, and energy dissipation predicted by the three analysis models were compared and analyzed. The results were similar to those tested in the order of the fiber, Pivot, and Takeda models, whereas the fiber model took the most time to build. For columns subjected to axial load, the Pivot model could predict the behavior at a similar level to that of the fiber model. Based on the above, it is expected that the Pivot model can be applied most practically for existing RC columns.

The Effect of Calcium on Microstructure of AZ61 Magnesium Alloy during Annealing Heat Treatment (AZ61 마그네슘 합금의 어닐링 중 Ca의 첨가에 따른미세조직 변화에 미치는 영향)

  • Kim, Kibeom;Jeon, Joonho;Kim, Kwonhoo
    • Journal of the Korean Society for Heat Treatment
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    • v.34 no.2
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    • pp.53-59
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    • 2021
  • Due to high specific strength and low density, AZ series magnesium alloys have been receiving high interest as a lightweight material. However, their industrial application is limited due to the phenomenon that the strength decreases at elevated temperature by the occurrence of softening effect because of the Mg17Al12 phase decomposition. To solve this problem, many research were conducted to increase the high-temperature strength by forming a thermal stable second-phase component by adding new elements to the AZ magnesium. Especially, adding Ca to AZ magnesium has been reported that Ca forms the new second-phase. However, studies about the analysis of decomposition or precipitation temperature, formation composition, and components to understand the formation behavior of these precipitated phases are still insufficient. Therefore, the effect of Ca addition to AZ61 on the phase change and microstructure of the alloy during annealing was investigated. As a result of analysis of the initial and heat-treated specimen, AZ61 formed α-Mg matrix and precipitated phase of Mg17Al12, and AZX611 formed one more type of precipitated phase, Al2Ca. Also, Al2Ca was thermal stable at high temperatures. And after annealing, the laves phase was decomposed to under 10 ㎛ size and distributed in matrix.

Change of Statical Behavior and Ultimate Capacity of Steel Cable-stayed Bridges after Cable Failure (케이블 단선 후 강사장교의 구조 및 극한 거동 변화)

  • Kim, Seung-Jun;Choi, Jun-Ho;Won, Deok-Hee;Han, Taek-Hee;Kang, Young-Jong
    • Journal of Korean Society of Steel Construction
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    • v.23 no.6
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    • pp.747-761
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    • 2011
  • This paper presents an investigation on the change in the statical behavior and the ultimate capacity of steel cable-stayed bridges after cable failure. Cable failure can occur due to fire, direct vehicle clash accidents, cable or anchorage fatigue, and so on. Moreover, the cable may be temporarily disconnected during cable replacement work. When cable failure occurs, the load, that was supported by the broken cable is first transferred to another cable. Then the structural state changes due to the interaction between the girder, mast, and cables. Moreover, it can be predicted that the ultimate capacity will decrease after cable failure, because of the loss of the support system. In this study, the analysis method is suggested to find the new equilibrium state after cable failure based on the theory of nonlinear finite element analysis. Moreover, the ultimate analysis method is also suggested to analyze the ultimate behavior of live loads after cable failure. For a more rational analysis, a three-step analysis procedure is suggested and used, which consisted of initial shape analysis, cable failure analysis, and live load analysis. Using this analysis method, an analytical study was performed to investigate the changes in the structural state and ultimate behavior of steel cable-stayed bridges.

An Experimental Study on the Durability and Load Carrying Capacity of RC Structure Repair System Using FR-ECC (고인성 내화보수모르터(FR-ECC)를 활용한 RC 구조물 보수공법의 내구성능 및 내하력에 관한 실험적 연구)

  • Kim, Jeong Hee;Lim, Seung Chan;Kim, Jae Hwan;Kwon, Yung Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.2
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    • pp.75-86
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    • 2012
  • This paper presents some research results on the shrinkage characteristics and frost resistance before and after cracking of FR-ECC(Fire Resistance-Engineered Cementitious Composite). Also, a waterstop performance and exfoliating resistance of multi-layer lining specimens using FR-ECC and flexural performance of beam member by repaired FR-ECC are estimated in this paper. Experimental results indicate that the plastic shrinkage crack and length change ratio of FR-ECC have been reduced as compared with that of the existing repair mortar, and that its crack resistance on the dry shrinkage is improved under the confining stress. As well as FR-ECC has been great in the frost resistance and its tensile properties under the cracked state have been not reduced by freezing and thawing reaction. In addition, beam member by repaired FR-ECC have been increased in the flexural properties such as initial crack moment, yeild moment, and its crack width has been controled in a stable by the frexural failure.

Analysis of Applicability of Rapid Hardening Composite Mat to Railway Sites (초속경 복합매트의 철도현장 적용성 분석)

  • Jang, Seong Min;Yoo, Hyun Sang;Oh, Dong Wook;Batchimeg, Banzragchgarav;Jung, Hyuk Sang
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.44 no.1
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    • pp.109-116
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    • 2024
  • The Rapid Hardening Composite Mat (RHCM) is a product that improves the initial strength development speed of conventional Geosynthetic Cementitious Composite Mats (GCCM). It offers the advantage of quickly securing sufficient strength in railway slopes with insufficient formation level, and provides benefits such as preventing slope erosion and inhibiting vegetation growth. In this study, an analysis of the practical applicability of RHCM in railway settings was conducted through experimentation. The on-site applicability was assessed by categorizing it into fire resistance, durability, and stability, and conducting combustibility test, ground contact pressure test, and daily displacement analyses. In the case of South Korea, where a significant portion of the territory is composed of forested areas, the prevention of slope fires is imperative. To analyze the fire resistance of RHCM, combustibility tests were conducted as an essential measure. Durability was assessed through ground contact pressure tests to analyze the deformation and potential damage of RHCM caused by the inevitable use of small to medium-sized equipment on the construction surface. Furthermore, daily displacement analysis was conducted to evaluate the structural stability by comparing and analyzing the displacement and behavior occurring during the application of RHCM with railway slope maintenance criteria. As a result of the experiments, the RHCM was analyzed to meet the criteria for heat release rate and gas toxicity. Furthermore, the ground contact pressure was observed to be consistently above 50 kPa during the curing period of 4 to 24 hours under all conditions. Additionally, the daily displacement analyzed through field site experiments ranged from -1.7 mm to 1.01 mm, confirming compliance with the criteria.