• Fire Science and Engineering
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• v.34 no.3
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• pp.141-149
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• 2020

The Korea Industrial Standards (KS) stipulates methods and test procedures for measuring the horizontal combustibility of cellular plastics exposed to small flames (KS M ISO 9772:2018) and recommendations regarding the magnetic digestion of extruded polystyrene insulation (XPS) for measurement results (KS M 3808:2020). Although products that are certified to conform to KS standards must have burning characteristics (self-extinguishing), they are incinerated and spread by welds at construction sites, causing significant human and property damages. In this study, XPS produced by five companies, certified by KS, and sold in the market were purchased and tested for ignition and diffusion caused by a weld bullion at a construction site. The results showed that the five products had differences in performance. Three out of the five products were found to be self-saturated, but the other two were easily ignited and diffused, making it difficult for them to be self-extinguishing. Based on the result of this experimental investigation in line with the KS regulations, all the three types of products, including two types of products that were incinerated through weld defects, were found to be non-self-extinguishing, as specified in KS M 3808.

• Fire Science and Engineering
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• v.23 no.6
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• pp.1-9
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• 2009

In this study, the burning behaviours of five different kinds of carpet samples covered with nylon, PP (polypropylene), PTT (poly(trimethylene terephthalate)), wool fabric and NW (nylon and wool) were evaluated by using the cone calorimeter having a radiant flux of 50kW/$m^2$. And the combustion gas toxicity was evaluated according to KS F 2271 test method. As a result of the cone calorimeter test (KS F ISO 5660-1), nylon carpet samples were ignited most easily. In ignition ability or initial flammability, NW carpet samples showed the highest value. In heat release rate (HRR), fire intensity, PP carpet samples were larger than any other samples. Nylon carpet samples were the highest smoke production rate, while N/W carpet samples the lowest. The following were in mass loss rates: NW > wool > nylon > PP > PTT. CO (carbon monoxide) was one of the most toxic gases released from the combustion. PTT carpet samples gave rise to the highest CO concentration, while NW carpet samples the lowest. In addition, PP carpet samples caused the highest $CO_2$ (carbon dioxide) concentration, while NW carpet samples the lowest. Toxicity of the gas produced from carpet samples was determined by the mouse stop motion, and it resulted in the fact that the combustion gas of PTT carpet samples was more toxic than that of any other samples.

• 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.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.25-36
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• 2021

Hydrogen in hydrogen-electric vehicles has a wide range of combustion and explosion ranges, and is a combustible gas with a very fast flame propagation speed, so it has the risk of leakage, diffusion, ignition, and explosion. The fuel tank has a Thermally active Pressure Relief Device (TPRD) to reduce the risk of explosion and other explosions, and in the event of an accident, hydrogen inside the tank is released outside before an explosion or fire occurs. However, if an accident occurs in a semi-closed space such as an underground parking lot, the flow of air flow is smaller than the open space, which can cause the concentration of hydrogen gas emitted from the TPRD to accumulate above the explosion limit. Therefore, in this study, the leakage rate and concentration of hydrogen over time were analyzed according to the diameter of the nozzle of the TPRD. The diameter of the nozzle was considered to be 1 mm, 2.5 mm and 5 mm, and ccording to the diameter of the nozzle, the concentration of hydrogen in the underground parking lot increases in a faster time with the diameter of the nozzle, and the maximum value is also analyzed to be larger with the diameter of the nozzle. In underground parking lots where air currents are stagnant, hydrogen concentrations above LFL (Lowe Flammability Limit) were analyzed to be distributed around the nozzle, and it was analyzed that they did not exceed UFL (Upper Flammability Limit).

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.3
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• pp.21-36
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• 2019

Dead fuel moisture content is a key variable in fire danger rating as it affects fire ignition and behavior. This study evaluates simple regression models estimating the moisture content of standardized 10-h fuel stick (10-h FMC) at three sites with different characteristics(urban and outside/inside the forest). Equilibrium moisture content (EMC) was used as an independent variable, and in-situ measured 10-h FMC was used as a dependent variable and validation data. 10-h FMC spatial distribution maps were created for dates with the most frequent fire occurrence during 2013-2018. Also, 10-h FMC values of the dates were analyzed to investigate under which 10-h FMC condition forest fire is likely to occur. As the results, fitted equations could explain considerable part of the variance in 10-h FMC (62~78%). Compared to the validation data, the models performed well with R2 ranged from 0.53 to 0.68, root mean squared error (RMSE) ranged from 2.52% to 3.43%, and bias ranged from -0.41% to 1.10%. When the 10-h FMC model fitted for one site was applied to the other sites, $R^2$ was maintained as the same while RMSE and bias increased up to 5.13% and 3.68%, respectively. The major deficiency of the 10-h FMC model was that it poorly caught the difference in the drying process after rainfall between 10-h FMC and EMC. From the analysis of 10-h FMC during the dates fire occurred, more than 70% of the fires occurred under a 10-h FMC condition of less than 10.5%. Overall, the present study suggested a simple model estimating 10-h FMC with acceptable performance. Applying the 10-h FMC model to the automatic mountain weather observation system was successfully tested to produce a national-scale 10-h FMC spatial distribution map. This data will be fundamental information for forest fire research, and will support the policy maker.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.481-486
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• 2014

This study was performed to test combustive properties of medium density fibreboard (MDF) plates treated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), and N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP). MDF specimens were painted three times with 15 wt% solution of the alkylenediaminoalkyl-bis-phosphonic acids at room temperature. After drying specimen treated with chemicals, combustive properties were examined using the cone calorimeter (ISO 5660-1). As a result, combustion-retardation properties increased due to the treatment of bare MDF with alkylenediaminoalkyl-bis-phosphonic acid solution. Especially, the specimens treated with chemicals showed the ignition (TTI) (148 s~116 s) was retarded and the flameout (Tf) (633 s~529 s) time increased, while the total heat release rate (THRR) (61.1~67.0) $MJ/m^2$ was lowered than those of using virgin plate by reducing the burnig rate. Compared with virgin MDF plate, the specimens treated with the alkylenediaminoalkyl-bis-phosphonic acids showed low combustive properties. However the specimens treated with bis-(dimethylaminomethyl) phosphinic acid (DMDP) showed the higher peak heat release rate (PHRR) ($185.08kW/m^2$) than that of the virgin plate.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.603-608
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• 2010

A study has been conducted experimentally to investigate behavior of ignition and flame spread over metal dust deposits with particle size using by a developed apparatus and thermogravimetric analysis(TGA). Zr, Ta and Mg-Al(90:10 wt%) alloy metal powders including Mg and Ti with different particle size were used. Also we used PMMA(Polymethylmethacrylate) powder to compare the combustion properties to those of metal powders. When dust layers were more than 5 mm in thickness, the dependency of deposit depth on flame spread rate over dust layer was not shown. With decreasing mean particle diameter, flame spread rate over Ti dust layer decreased, while the spread rate over Mg dust layer increased. For mean diameter of $51{\mu}m$, fire spread rate over pure Mg dust layer decreased to about 50 percent in Mg-Al(90:10 wt%) dust layer. The oxide thickness of metal dust used in this study tended to be inversely proportional with the spread rate, and it was quite small for influence with particle size. From the results of TGA for Ti and Mg, weight increasing curves(550 for Mg, 578 for Ta) were observed in the oxidation process, and they seems to be caused by ignition of upper dust layer.

• Journal of The Korean Society of Clinical Toxicology
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• v.10 no.2
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• pp.80-85
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• 2012

Purpose: The aim of this study was to describe the epidemiologic characteristics of adult patients with carbon monoxide poisoning who presented to the emergency department in recent years. Methods: This was a retrospective cohort study on adult consecutive patients with carbon monoxide (CO) poisoning who presented to the emergency department of a tertiary care university-affiliated hospital from January 1, 2008 to December 31, 2011. Results: A total of 91 patients were included in this study; there were 56(61.5%) unintentional and 35(38.5%) intentional poisonings. For the unintentional CO poisonings, the principal sources of exposure to CO were fire (39.3%), charcoal (17.9%), briquette charcoal (7.1%), wood burning boiler (7.1%), gas boiler (5.4%), automobile heater (3.6%), briquette boiler (3.6%), firewood (3.6%), and other items (12.5%). For the intentional CO poisonings, the sources were ignition charcoal (60.0%), briquette (31.4%), charcoal (5.7%) and butane gas (2.9%). For the unintentional CO poisonings, the places of poisoning were the home (58.9%), workplace (10.7%), public accommodation (8.9%), tent (8.9%), automobile (3.6%) and parking place (1.8%). For the intentional CO poisonings, the places of poisoning were the home (77.1%), public accommodation (11.4%) and automobile (11.4%). The proportion of intentional CO poisonings among total poisonings has increased significantly in recent years; 0.0% in 2008, 3.3% in 2009, 5.5% in 2010, and 29.7% in 2011. Conclusion: This study showed that in recent years in Korea, the source of CO has diversified broadly and intentional CO poisonings from burning ignition charcoal or briquettes has increased. Prevention efforts should consider these factors.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.28-33
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• 2011

The purpose of this paper analyzes and studies to improve the failure cases on the computer that one of electronic control elements for engine in liquified petroleum gas vehicle. The first case, it certified the non-starting phenomenon of engine that it's electronic control unit didn't control the fuel for idle speed actuator because of no given action signal in slow-cut solenoid valve. The second case, it knew the bad condition phenomenon of engine and back-fire by the wire melting of ignition coil and firing of transistor being inside ECU. The third case, it certified the action stoping phenomenon of engine and malfunctioning signal for engine ECU because of leakage of current and an excess current by moisture inflowing inside ECU curcuit plate. Therefore, it is thought that will elevate the durability and reliability of engine computer throughout procure of quality.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.89-95
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• 2016

Keeping the gas pipelines in the common utility tunnel is useful because it has a lower risk of corrosion than conventional burial, and can prevent from excavating construction. But, explosions in common utility tunnels can cause greater damage from the blast overpressure compared to outdoor explosions, due to nature of the confined environment. Despite this fact, however, research on common utility tunnels has been limited to fire hazard and little has been studied on the dangers of explosions. This study developed scenarios of methane gas explosion caused by gas leak from gas piping within the common utility tunnel followed by unknown ignition; the study then calculated the extent of the impact of the explosion on the facilities above, and suggested the needs for designing additional safety measures. Two scenarios were selected per operating condition of safety devices and the consequence analysis was carried out with FLACS, one of the CFD tools for explosion simulation. The overpressures for all scenarios are substantial enough to completely destroy most of the buildings. In addition, we have provided additional measures to secure safety especially reducing incident frequency.