• Fire Science and Engineering
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• v.29 no.2
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• pp.39-43
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• 2015

The flash point is the major property to characterize fire and explosion hazard of liquid mixtures. The flash point is the lowest temperature at which a liquid gives off enough vapor to form a flammable air-vapor mixture. The flash points of two aqueous mixtures, water-methanol and water-ethanol, were measured using Seta flash closed cup tester. A prediction method based on activity coefficient models, Wilson and UNIQUAC equations, was used to calculate the flash point. The calculated flash points were compared to the results by the calculating method using Raoult's law. The calculated values based on activity coefficients models were found to be better than those based on the Raoult's law.

• Fire Science and Engineering
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• v.23 no.5
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• pp.50-56
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• 2009

Explosion limit and autoignition temperature are the major properties used to determine the fire and explosion hazards of the flammable substances. Explosion limit and autoignition temperature for safe handling of ethylene were investigated. By using the literatures data, the lower and upper explosion limits of ethylene recommended 2.6vol% and 36vol%, respectively. Also autoignition temperatures of ethylene with ignition sources recommended $420^{\circ}C$ at the electrically heated crucible furnace (the whole surface heating) and recommended about $800^{\circ}C$ in the local hot surface. The new equations for predicting the temperature dependence and the pressure dependence of the lower explosion limits for ethylene are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.87-93
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• 2003

Two-component polyurethane flame retardant coatings (ATTBC) were prepared by blending polyisocyanate (TDI-adduct) with ATTBs mentioned at the previous paper. Most of the physical properties of the flame retardant coatings were comparable to those of non-flame retardant coatings. Especially, the hardness, impact resistance, and accelerated weathering resistance were remarkably improved with the increase of the content of 1,4-butanediol. Coatings containing 10 and 15 wt% 1,4-butanediol, ATTBC-10C and ATTBC-15C, were not flammable in vertical flame-retardancy test. Their char area recorded 1.1${\sim}$11.6 $cm^2$ in 45$^{\circ}$ eckel burner method.

• Journal of computational fluids engineering
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• v.14 no.2
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• pp.32-38
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• 2009

In the present study, a numerical simulation for the diffusion of hydrogen jet in a enclosure was performed to aid the leakage test of the hydrogen for the safety of the hydrogen vehicle. The temporal and spatial distributions of the hydrogen concentration in the test chamber are predicted from the present numerical analyses. Flammable region of 4-74% and explosive region of 18-59% hydrogen by volume was identified from the present results. Factors influencing the diffusion of the hydrogen jet were examined to evaluate the effectiveness of forced ventilation for relieving the accumulation of the leaked hydrogen gas in the chamber, which include location of open windows, size of leakage nozzle, and leakage rate among others. The distribution of the concentration of the leaked hydrogen for various cases can be used as a database in various applications for the hydrogen safety.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2192-2197
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• 2008

An experimental study was performed to investigate the effects of configuration of burner and air excess ratio on CO & NOx emission characteristics of the cooktop burners which are used extensively. In this study, the combustion characteristics were investigated with the variation of design factor of cooktop burners. The results showed that as the thermal input increases, flammable region go narrower. With the increase of loading height from the cap to grate, the CO emission decrease owing to the reduction of quenching by flame impingement on the load. Additionally, the CO emission increase with angle of main slot, however the NO emission is almost unaffected.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.5
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• pp.351-358
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• 2008

Extinction characteristics of hydrogen-air diffusion flames at various pressures are investigated numerically by adopting counterflow flame configuration as a model flamelet. Especially, effect of radiative heat loss on flame extinction is emphasized. Only gas-phase radiation is considered here and it is assumed that $H_2O$ is the only radiating species. Radiation term depends on flame thickness, temperature, $H_2O$ concentration, and pressure. From the calculated flame structures at various pressures, flame thickness decreases with pressure, but its gradient decreases at high pressure. Flame temperature and mole fraction of $H_2O$ increase slightly with pressure. Accordingly, as pressure increases, radiative heat loss becomes dominant. When radiative heat loss is considered, radiation-induced extinction is observed at low strain rate in addition to transport-induced extinction. As pressure increases, flammable region, where flame is sustained, shifts to the high-temperature region and then, shrunk to the point on the coordinate plane of flame temperature and strain rate. The present numerical results show that radiative heat loss can reduce the operating range of a combustor significantly.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.3
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• pp.247-253
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• 2006

In this work, pool boiling heat transfer coefficients (HTCs) of hydrocarbon refrigerants are measured from a horizontal smooth tube of 19.0 mm outside diameter. Tested pure refrigerants are Propylene, Propane, Isobutane, Butane and Dimethylether (DME). The pool temperature was maintained at saturation temperature of $7^{\circ}C$ and heat flux was varied from $10kW/m^2$ to $80kW/m^2$ with an interval of $10kW/m^2$. Wall temperatures were measured directly by thermocouple hole of 0.5 mm out-diameter, 152 mm long and inserting ungrounded sheathed thermocouples from the side of the tube. Tested results show that HTCs of Propane, Propylene are 2.5%, 10.4% higher than those of R22 while those of Butane and Isobutane are 55.2%, 44.3% lower than those of R22 respectively. For pure refrigerants, new correlation can be applied to all of CFCs, HCFCS, HFCs, as well as hydrocarbons was developed. The mean deviation was 4.6%.

• Journal of the Korea Safety Management & Science
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• v.19 no.2
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• pp.31-39
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• 2017

Classify of explosion hazardous areas must be made at the site where flammable materials are used. This reason is that it is necessary to manage ignition sources in of explosion hazardous areas in order to reduce the risk of explosion. If such an explosion hazard area is widened, it becomes difficult to increase the number of ignition sources to be managed. The method using the virtual volume currently used is much wider than the result using CFD(Computational Fluid Dynamics). Therefore, we tried to improve the current method to compare with the new method using leakage characteristics. The result is a realistic explosion hazard if the light gas is calibrated to the mass and the heavy gas is calibrated to the lower explosion limit. However, it is considered that the safety factors should be taken into account in the calculated correction formula because such a problem should be considered as a buffer for safety.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.845-848
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• 2006

This study sought to investigate the characteristics of cellular concrete, such as porosity, strength and density, according to the cell addition rate. Based on the result, it examined the application to a cellular concrete panel. Porosity was found to increase according to the cell addition rate, measuring continuous porosity of 42% and 47%, and total porosity of 61% and 66%. In terms of cell addition rate, measurements were 7% and 11% respectively. Compressive strength represented 5.0MPa, 3.8MPa and 2.8 MPa in terms of 7%, 9% and 11% respectively, decreasing 1 MPa of strength according to every 2% increase of cell addition rate. Density showed 0.55, 0.44 and 0.36 in terms of 7%, 9% and 11% respectively, decreasing 1.0 MPa according to every 2% increase of cell addition rate proportionally. In addition the sandwich panel of cellular concrete which was fabricated during this research was found to be relatively heavy and non-flammable with an excellent strength of 4.0 MPa. Compared with a light concrete panel, considering the compressive strength that accountsfor 10 MPa, it appeared relatively low in strength. However it would be excellent for application due to the light density of only 0.4 MPa.

• Journal of the Korean Institute of Gas
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• v.11 no.3
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• pp.13-18
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• 2007

The multivariate statistical analysis, using the multiple linear regression(MLR), have been applied to analyze and predict the flash points of binary systems. Prediction for the flash points of flammable substances is important for the examination of the fire and explosion hazards in the chemical process design. In this paper, the flash points are predicted by MLR based on the physical properties of pure substances and the experimental flash points data. The results of regression and prediction by MLR are compared with the values calculated by Raoult's law and Van Laar equation.