• Fire Science and Engineering
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• v.28 no.3
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• pp.29-33
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• 2014

Cleanroom fires were simulated by using Fire Dynamics Simulator. A grid size of $0.5{\times}0.5{\times}0.2m^3$ was selected following review of grid sizes. Fires in three large cleanrooms were investigated to confirm safety by applying the requirements on temperature, visibility, and carbon monoxide concentration in performance based design. The worst situation without sprinkler system and air flow of 0.1 m/s downward in the cleamrooms was considered. It was confirmed that all the three cleanrooms were safe in case without sprinklers since the temperature was below the safety requirement. Decrease in visibility and carbon monoxide concentration due to the fires were negligible.

• Fire Science and Engineering
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• v.26 no.1
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• pp.68-73
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• 2012

Performance-based design (PBD) for large scale high rise buildings has been enforced to secure fire and evacuation safety since July 1, 2011. As various types of trial and error were expected in the early stage, to suggest solutions to the problems that might be followed by the enforcement, the regulations on PBD were reviewed and a questionnaire survey to fire protection specialists was carried out. It was confirmed that PBD is required for large scale apartment buildings, and specific and detail criteria for PBD methodology and evaluations, education for PBD to personnel who design and evaluate are also in need.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.8-12
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• 2005

A fire in a clean room may cause a serious loss by spreading smoke particles. The effects of the width of smoke curtains on delay in smoke spread, which is located the work area boundaries, were investigated by using a computational fluid dynamics, for loss prevention by smoke spreading from one fire area to another. The fire scenario was set to a 1 MW methanol fire in a space of $30m\times10m$ floor and 4 m high. Distributions of temperature and smoke particles were compared for the width of the smoke curtains 0 (without smoke curtains), 1, 2, 3m. It was confirmed that a larger width of the smoke curtain delays spread of smoke more, and that making the work areas compartments is necessary to confine the smoke in the fire area.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.107-111
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• 2002

A near extinction nonpremixed counterflow flame of 19% methane diluted by 81% nitrogen by volume and undiluted air at a low global strain rate, 20 s-1, was computed. Investigations were focused on effects of the duct thickness and velocity boundary conditions on the flame structure in normal and zero gravity conditions. The results showed that, under normal gravity conditions, the effects of the duct thickness and velocity boundary conditions were significant by shifting the flame position, but negligible in zero gravity. The differences in flame structure were caused by buoyancy, and hence should be considered in the measurements in normal gravity.

• Journal of the Korean Society of Safety
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• v.17 no.2
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• pp.112-117
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• 2002

The effects of shield gas on the structure of methane-air nonpremixed counterflow flames were numerically investigated. The near extinction flame of a low global strain rate 20 $s^{-1}$ of 19% methane diluted by 81% nitrogen by volume and undiluted air was computed. The flame shape, centerline temperature and axial velocity profiles were compared for different velocity of the shield gas and with and without the shield gas. The effects of the velocity of the shield gas were negligible for $V_{S}/V_{F}{\leq}2$ in normal gravity. Under normal gravity conditions, the flame shape and its position with the shield gas were different from those of the flame without the shield gas, whereas no discernible effects of the shield gas along the centerline were observed in zero gravity.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.725-733
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• 2008

A thixotropic grout has been developed for the use of filling a tail void in the shield TBM and as well as various ground voids. The grout developed in this study is a mixture of inorganic substance, cement and some functional additives. Its engineering characteristics was investigated by measuring a viscosity and unconfined compressive strengths. The optimum mix proportion for an effective thixotropic grout was proposed through several repeated laboratory tests. The various physical properties such as thixotropy, unconfined compressive strengths, and durability of the thixotropic grout and the gels produced from the grout were compared with those of the well-known waterglass-type grout such as L.W.. The thixotropic grout developed in the study exhibited an excellent performance for back-filling of tail voids in the shield TBM based on experimental results compared to the existing waterglass grout.

• Journal of the Korean Institute of Gas
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• v.12 no.1
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• pp.25-30
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• 2008

A Numerical study was carried out for a propane gas pool fire in the fire test room of $2.5m{\times}2.0m{\times}2.5m$ for testing a inert gas water mist system, to investigate a possible under-ventilation in the fire test room. For the fire sizes of 60 kW and 120 kW, changes in the temperature and CO concentration with and without a window were investigated. It was confirmed that the influence of the window on the distributions of temperature and CO concentration was small in the two fire sizes, and hence the under-ventilation was not occurred in the room.

• Fire Science and Engineering
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• v.17 no.3
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• pp.20-25
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• 2003

Measurements with filaments and thermocouples and computations with Oppdif and FDS were carried out to investigate the impact of flame strain, agent addition, and buoyancy on the structure and extinction of nonpremixed counterflow flames. Measurements through 2.2 s drop tests in microgravity conditions and experiments in normal gravity conditions were compared with the results of computations. For the global strain rates 7 s$^{-1}$ through 100 s$^{-1}$ , the turning point behavior in the critical nitrogen concentration at O-g was confirmed. The effects of buoyancy, that is, changes in the flame curvature and thickness were also confirmed by the computations with FDS. There was agreement in the peak flame temperature and its position between the computations and the measurements in the near extinction methane/air diffusion flames in microgravity.

• 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.20 no.2 s.62
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• pp.8-13
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• 2006

Numerical simulations were carried out for a fire in a clean room to confirm needs of a smoke control system and a sprinkler system, and to investigate a possible smoke spread-out. For a 1 MW methanol fire in a space of $39m{\times}13m$ floor and 4 m high, smoke spread-out was scrutinized for failure of the sprinkler system and/or the smoke control system. It was shown that the smoke control system removes smoke safely without the sprinkler system and that the sprinkler system is required to suppress smoke generation and spread of the fire, and to remove the smoke quickly. It was also confirmed that highly reliable sprinkler heads and automatic fire detection system are required for the sprinkler and smoke control systems.