• Fire Science and Engineering
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• v.33 no.5
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• pp.48-54
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• 2019

A Large Eddy Simulation (LES), adopting the Eddy Dissipation Concept (EDC) 1-step model, was successfully performed for backdraft phenomena. The activation energy of the finite chemistry reaction in the EDC 1-step model was adjusted to simulate the backdraft. The prediction of the EDC 1-step model was similar to that of the Mixing-Controlled Fast Chemistry (MCFC) model, except when the backdraft occurred. The EDC 1-step model could be used to simulate the experimental peak pressure, but not the first peak pressure of the backdraft.

• Fire Science and Engineering
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• v.31 no.4
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• pp.35-42
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• 2017

Large Eddy Simulation (LES) was peformed for the backdraft occurred in a compartment filled with high-temperature methane fuel using the Fire Dynamics Simulator (FDS) of version 6. The prediction performance of FDS, adopted the Eddy Dissipation Concept (EDC) combustion model with five different chemical reaction mechanisms, was evaluated. The temporal distributions of temperature, fuel mass fraction, velocity and pressure were discussed with numerical results and the pressure variation in time was compared with that of previous experiment. The FDS adopted the EDC model showed the possibility of LES for the backdraft phenomena. However, the prediction performance of the LES with EDC model strongly depended on the chemical reaction mechanism considered. It is necessary that the suitability of the chemical reaction mechanism should be validated in advance for LES with the FDS v6 to be applied to the simulation of backdraft.

• Fire Science and Engineering
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• v.33 no.1
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• pp.30-38
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• 2019

Mixing characteristics and backdraft dynamics were investigated using large eddy simulation for compartments initially filled with methane fuel. Four different opening geometries, i.e. conventional door opening case (Door) and the cases where horizontal door was implemented on the upper ($Slot_U$), middle ($Slot_M$) and lower part ($Slot_L$) of side wall, were considered in the simulations. For cases without ignition, the amounts of inflow oxygen and outflow fuel from the compartment opening were, from largest to smallest, Door > $Slot_U$ ~ $Slot_M$ > $Slot_L$. However, the fuel and oxygen were the best mixed for the $Slot_U$ case while the fuel and oxygen were not well mixed and in relatively separated two layers for the $Slot_L$ case. The global equivalence ratio defined by the amounts of fuel and oxygen in the compartment was not correlated reasonably with the peak pressure of backdraft. The peak pressure during backdraft was the highest for the $Slot_U$ case, a well mixed condition of fuel and air, and backdraft was not found for the $Slot_L$ where the pressure rise was not so high due to the mixing status. The peak pressures for the Door and $Slot_M$ cases were in between Door and $Slot_L$ cases. The peak pressure during backdraft was well correlated with the total amount of heat release until the instance of backdraft occurrence.

• Fire Protection Technology
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• s.39
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• pp.5-5
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• 2005

• Electronics and Telecommunications Trends
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• v.24 no.1
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• pp.43-49
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• 2009

최근 높은 대역폭을 요구하는 다양한 IP 멀티미디어 애플리케이션이 증가하면서 10G 이더넷 서비스가 폭넓게 이용되고 있으나, 이도 가까운 시기에 트래픽의 한계에 이를 것에 대비하여 보다 큰 대역폭을 제공할 수 있는 40G급 이더넷 기술에 관한 표준화 드래프트 1.0 규격이 이더넷은 IEEE 802.3ba에 의해 2008년 9월 완성되었으며 2009년 완료를 목표로 하고 있다. 본 고에서는 표준화 기술이 어떻게 채택되고 있는지를 알아보고, 40G 표준화 이더넷 백플레인 기술 및 등화기 구현방안에 대하여 기술한다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2007.04a
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• pp.264-269
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• 2007

• Journal of the Korean Society of Safety
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• v.28 no.6
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• pp.6-10
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• 2013

A numerical reproducibility of the backdraft phenomena in a compartment was investigated. The prediction performance of two combustion models, the mixture fraction and finite chemistry models, were tested for the backdraft phenomena using the FDS code developed by the NIST. The mixture fraction model could not predict the flame propagation in a fuel-air mixture as well as the backdraft phenomena. However, the finite chemistry model predicted the flame propagation in the mixture inside a tube reasonably. In addition, the finite chemistry model predicted well the backdraft phenomena in a compartment qualitatively. The flame propagation inside the compartment, fuel and oxygen distribution and explosive fire ball behavior were well simulated with the finite chemistry model. It showed that the FDS adopted with the finite chemistry model can be an effective simulation tool for the investigation of backdraft in a compartment.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.381-388
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• 2016

In this study, we surveyed the supply and perception of Personal Protective Equipments for firefighters. As a result, most of the respondents answered that they were paid in accordance with the supply standard, but 12% of the respondents said that there were insufficient equipment. Also, satisfaction with the performance of the equipment is mostly satisfied, but the safety gloves are more than 50% dissatisfied. In summing up the results of the survey, it is urgently necessary to improve the current supply standard, which is determined by the life of PPE, to the replacement period according to the using time or frequency. Also, a new standard should be prepared through the follow - up study.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.1-8
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• 2016

The behavior of backdraft in the compartment with different ignition locations and times was numerically investigated. The Fire Dynamics Simulator (FDS) v5.5.3 with a model-free simulation option was used in the numerical simulation of backdraft. The ignition source was located near the inside wall, at the compartment center and near the window opening, respectively. The ignition was started at the instance when the fresh air reached the ignition location or when a sufficient time passed compare to the instance of the arriving of the fresh air to the ignition location. As a result, for the ignition source was located near the inside wall, a strong fire ball was observed at once and the result was similar to the previous experimental result. For the ignition source was located at the center of the compartment, a strong fire ball was occurred and two strong fire balls were observed consecutively for the ignition time was delayed. For the ignition source was located near the window opening and longer time was given for the ignition compare the duration of the fresh air arriving to the ignition location, the rapid temperature variation was not observed because there was no flame. However, for the ignition was started at the instance when the fresh air reached the ignition location, the ignition could be initiated and a intensive fire ball was observed. The pressure measured at the upper inside part of the window opening provided a similar trend with the previous experimental result of compartment backdraft.

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.529-536
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• 2017

In this study, the perceptions were surveyed fire risk and flash flames concerning the firefighters. The results were statistically evaluated according to age, experience and rank. More than 70% of the respondents answered that there is a possibility of unexpected flame exposure in the field of fire, but there was no recognition difference according to age, experience and rank. However, if there is an emergency situation in the field of fire, the survey on the ability to cope with crises showed that there is a difference in perception depending on the age, career, and rank of respondents. From these results, it is expected that strengthening simulation training of unexpected situation will be more urgently required in the future, and measures should be taken to minimize human accidents through improvement of standard operation procedures or supplement of fire suppression education according to unexpected situation.