• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.625-629
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• 2006

This paper describes the effect of the droplet breakup process on fire suppression using a water-mist system, which is considered as a alternative to sprinkler fire suppression system. In the evolution of the water-mist, the droplet breakup process is an important phenomenon because it may significantly affect the droplet evaporation rate. The Fire Dynamics Simulator (FDS, Ver. 4.0) code, which is widely used for the simulation of fire dynamics, is used for the present simulation, and it is modified to consider the droplet breakup phenomena. The Prediction by the modified code shows good agreement with experimental data for the temperature. The original FDS predicts higher temperature about $30^{\circ}C$ than experimental data. From the results, it is concluded that the droplet breakup phenomena must be considered for more precise simulation of fire suppression process.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.241-242
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• 2022

In this study, fire simualtion was performed to examine the necessity of smoke control system in the tunnel fire. The heat release rate was set to 5 MW and 20MW, and the visibility was measured at 1.8 m, which is the breathing limit, when there is no jet fan. Through this, it was confirmed that 5 MW did not affect the visibility even without the jet fan, and in the case of 20 MW, a jet fan was required to secure the visibility. The visibility was measured at the same location by installing the jet fan, and the simulation was performed by reducing the design volume flow rate of 8.5 m³/s by 80% and 50%, respectively. As a result, it was confirmed that sufficient visibility was secured when the design flow rate and 80% were reduced.

• International journal of steel structures
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• v.18 no.4
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• pp.1177-1190
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• 2018

This study presents an analytical framework for estimating the thermo-mechanical behavior of a composite beam exposed to fire. The framework involves: a fire simulation from which the evolution of temperature on the structure surface is obtained; data transfer by an interface model, whereby the surface temperature is assigned to the finite element model of the structure for thermo-mechanical analysis; and nonlinear thermo-mechanical analysis for predicting the structural response under high temperatures. We use a plastic-damage model for calculating the response of concrete slabs, and propose a method to determine the stiffness degradation parameter of the plastic-damage model by a nonlinear regression of concrete cylinder test data. To validate simulation results, structural fire experiments have been performed on a real-scale steel-concrete composite beam using the fire load prescribed by ASTM E119 standard fire curve. The calculated evolution of deflection at the center of the beam shows good agreement with experimental results. The local test results as well as the effective plastic strain distribution and section rotation of the composite beam at elevated temperatures are also investigated.

• Journal of the Korea Safety Management & Science
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• v.25 no.4
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• pp.67-72
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• 2023

Human and material damage can be reduced if the risk is evaluated by engineering analysis of fire combustion products, smoke concentration, and smoke movement speed in the event of a fire in apartment houses and officetels. In this study, a lot of research on related safety evaluation in the basement needs to be studied and reflected in design, so experimental research was conducted to analyze the flow of smoke through computer simulation and provide analysis data through evacuation safety evaluation. First of all, the five-story underground parking lot subject to simulation has a large floor area, which is advantageous for improving evacuation safety performance, but it uses temperature detectors to increase detection time and fire spread speed. Second, it was analyzed that the evacuation time at all evacuation ports did not exceed the evacuation time, and as the time from the start of evacuation to the evacuation time was 216.9% compared to the travel time, it was evaluated that the safety performance of the evacuation was secured. Third, the above simulation results are a comprehensive safety evaluation based on the non-operation of fire extinguishing facilities in the fire room to increase safety, which means that smoother evacuation safety performance can be secured by linking fire extinguishing facilities.

• Fire Science and Engineering
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• v.33 no.3
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• pp.112-120
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• 2019

To improve the reliability of a safety assessment using a fire simulation in domestic PBD, the evaluation method of ASET considering the uncertainties of the input parameters and numerical model of fire simulation was carried out. To this end, a cinema and officetel were selected as the representative fire spaces. The main results were as follows. Considering the uncertainty of the heat release rate, which has the greatest effect on the major physical quantities presented in the life safety standard, significant changes in temperature, CO, and visibility occurred. In addition, when the bias factors reflecting the uncertainty of the numerical model were applied, there were no significant changes in temperature and CO concentration. On the other hand, the visibility was increased considerably due to the low prediction performance of smoke concentration in FDS. Finally, the reason why the physical quantity determining the ASET in domestic PBD is mainly visibility was discussed, and the application of uncertainty of the input parameters and numerical model in a fire simulation was suggested for an accurate ASET evaluation.

• Fire Science and Engineering
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• v.24 no.4
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• pp.69-78
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• 2010

In this study, Fire Hazards were evaluated through computer simulation using FDS program for an apartment fire accident. The results of fire simulation showed that the maximum heat release rate in the case of no sprinklers activation was 7,700 kW which was about 16 times of that in the case of sprinklers activation, 497 kW and there was a very high fire hazard due to the backdraft phenomenon when the door of fire room was forced to open. Regarding the hazard time of fire room temperature and detection time of detectors, available evacuation time was 32.5 seconds of minimum to 53.5 seconds of maximum. In the case of sprinklers activation, fire hazard in the apartment was showed to be very low due to the fire control by the spray cooling of sprinklers. This study shows that what a important function for fire safety is the activations of fire sprinkler system and emergency alarm system and what a large loss can cause if these systems don’t activate in fire accidents.

• Fire Science and Engineering
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• v.30 no.1
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• pp.12-16
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• 2016

Propane fires of 1000 to 3000 kW in the ISO 9705 fire room were simulated using FDS to study the problem of decreasing temperature with increasing fire size. A criterion is proposed for under-ventilated fires. The computed temperature at 2000 kW and above was lower than that at 1500 kW. The heat release rate was limited by a lack of oxygen in the simulation. It was found that the heat release rate can therefore be a criterion for under-ventilated fires in simulations. Fires of 1700 kW and above in the ISO 9705 fire room are predicted to be under-ventilated.

• Fire Science and Engineering
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• v.30 no.5
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• pp.144-150
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• 2016

An apartment house with a pilotis that raises the architectural volume and provides a space for circulation is becoming popular. With the popularity of pilotis in apartment houses, people also have a keen interest in the potential fire risk at the pilotis. As residents can only access their apartment house through the pilotis, there is a risk to the occupants if there is fire there. Therefore, this study evaluated the pilotis fire cases of urban multifamily housing to conduct a Fire Dynamics Simulator (FDS) and Fire Evacuation Simulation (FES). Through these two simulation methods, it is possible to validate the riskiness of fire at an apartment with a pilotis. The study identified that the toxic gases and flame spread out to the pilotis within hundred seconds after ignition. In addition, the toxic gases and flame also reach the second floor within three seconds and the entire building within 735 seconds if the entrance doors at the pilotis are opened. On the other hand, the FES simulation results showed that it also takes about approximately 609 seconds to excavate from the apartment house with a pilotis. Therefore, this research shows that an apartment house with a pilotis can ensure the building occupants' lives and their safety if there is fire.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.142-147
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• 2009

In the present study, a numerical simulation of passenger evacuation in a subway station was performed. Algorithm for passenger flow analysis based on DEM(Discrete Element Method) has been improved to simulate passenger flow in detailed geometry. The effect of grid density was assessed in the present study to show the advantage of using finer grid in the simulation. The method of coupling passenger flow and fire simulation has also been investigated to analyze passenger evacuation flow under fire. In this method the CO distributions in the subway station was used to assess fire hazards of passenger by means of FED(Fractional Effective Dose) model. Using the coupled algorithm a simulation for passenger evacuation flow and fire analysis were performed simultaneously in the simplified subway station. This algorithm could be used in the design of subway station for the purpose of passengers' safety in case of fire.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.51-52
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• 2022

In previous studies, fire simulation was used to estimate the fire spread path. According to previous studies, the fire spread path was estimated to be the main staircase, but consideration of interior materials and internal bulkheads was insufficient. In this study, the ignition time of the 3rd layer was analyzed using the prediction formula considering the interior materials and internal bulkheads. As a result of referring to the architectural drawings, it was found that the interior material of the 3rd floor was made of polystyrene. The internal ignition time of the third floor using FDTs was calculated to be 14,070 seconds (about 234 minutes). The internal ignition time of the 3rd floor using the Handbook on Design Calculation Methods of Fire Behavior was calculated to be 3,104 seconds (about 51 minutes). As a result of calculating the ignition time through the predictive formula, there is a large difference in the ignition time, so it is necessary to review the condition of the variable as a result of the calculation in the future.