• 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 Society of Disaster Information
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• v.19 no.3
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• pp.673-688
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• 2023

Purpose: Fires that occur during construction are infrequent, but cause great damage. Recently, with the growth of the logistics and distribution industry, the number of construction sites for new logistics warehouses is increasing, so it was selected as a research subject and research was conducted to reduce accidents at construction sites through the development of a fire risk assessment tool to quantitatively approach fire prevention. Method: A comprehensive fire risk assessment tool was accumulated by classifying the work in progress, classifying combustibles and ignition sources by grade, excluding air (oxygen), which is difficult to control, and additionally substituting evacuation safety. Result: Using the developed and proposed fire risk evaluation tool, excavation work with low fire risk, facility construction with medium fire risk, and finishing work with high fire risk were sampled to derive the result (CGI). Conclusion: In this study, it was possible to establish specific preventive measures and evaluate evacuation safety by controlling physical conditions (combustibles) and energy conditions (ignition sources) according to the risk assessment by developing a tool that can evaluate the risk of 14fire occurrence at construction sites. It is expected that in the future, through the application of the fire risk evaluation tool at construction sites, it will be provided as a criterion for establishing a process plan that can reduce risk and evaluating the adaptability of firefighting equipment.14

• Fire Science and Engineering
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• v.24 no.2
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• pp.82-88
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• 2010

In this study, we have performed several tests for composite plastic materials to be applied on interior materials of a vehicle to identify their combustion characteristics using cone calorimeter, smoke density chamber and toxicity index chamber. We have prepared a total of 12 samples for 4 major parts of a vehicle wherein each major part has 3 different materials. The results of cone calorimeter test showed ignition time of PVC sheet and PVC leather were 2s. The 8 samples showed under less than 10s of ignition time. The sample comprising Nylon and PE had the biggest maximum heat release rate of 635 $kW/m^2$. The sample comprising Rubber showed the smallest maximum heat release rate but with the biggest total heat release. The results of smoke density chamber test showed the sample that is made up with Rubber had the biggest specific optical smoke density. The sample comprising PVC leather and PUR showed the biggest VOF4 which enables the initial smoke production. The results of toxicity index test showed that all samples contained carbon dioxide content exceeding its lethal concentration. The sample comprising PVC showed high content of hydrogen chloride and hydrogen bromide. The PVC sheet showed the biggest toxicity index calculated by using lethal concentration and test results. Toxicity index of all sample wes over 1.

• Fire Science and Engineering
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• v.28 no.6
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• pp.28-34
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• 2014

Two kinds of new piperazinomethyl-bis-phosphonic acid $M^{n+}$ ($PIPEABPM^{n+}$) were synthesized and their combustive properties of Pinus rigida plates treated with $PIPEABPM^{n+}$ were tested in comparison with the previously synthesized chemicals. Pinus rigida specimens were painted in three times with 15 wt% $PIPEABPM^{n+}$ solutions at the room temperature. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). As a result, the combustion-retardation properties were partially increased by due to the treated $PIPEABPM^{n+}$ solutions in the virgin Pinus rigida. Especially, the specimens treated with $PIPEABPM^{n+}$ showed both the lower peak heat release rate ($HRR_{peak}$) (173.48~145.36) s and total heat release rate (THRR) (73.0~55.2) $MJ/m^2$ than those of virgin piperazinomethyl-bis-phosphonic acid (PIPEABP)-plate. Compared with virgin PIPEABP-plate, the specimens treated with the $PIPEABPM^{n+}$ showed low combustive properties. However the specimens treated with $PIPEABPM^{n+}$ showed both the shorter time to ignition (TTI) (58~18) s and the time to flameout (Tf) (564~456) s than those of virgin PIPEABP-plate by increasing the thermal conductivity.

• Korean Journal of Materials Research
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• v.33 no.1
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• pp.15-20
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• 2023

'Tracers' are bullets that emit light at the backside so that the shooter can see the trajectory of their flight. These light-emitting bullets allow snipers to hit targets faster and more accurately. Conventional tracers are all combustion type which use the heat generated upon ignition. However, the conventional tracer has a fire risk at the impact site due to the residual flame and has a by-product that can contaminate the inside of the gun and lead to firearm failure. To resolve these problems, it is necessary to develop non-combustion-type tracers that can convert heat to luminance, so-called 'thermoluminescence (TL)'. Here, we highly improve the thermoluminescence properties of MgB₄O₇ through co-doping of Dy³⁺+Ce³⁺ and Dy³⁺+Na⁺. The presence of doping materials (Dy³⁺, Ce³⁺, Na⁺) was confirmed by XPS (X-ray photoelectron spectroscopy). The as-synthesized co-doped MgB₄O₇ was irradiated with a specific radiation dose and heated to 500 ℃under dark conditions. Different thermoluminescence characteristics were exhibited depending on the type or amounts of doping elements, and the highest luminance of 370 cd/m² was obtained when Dy 10 % and Na 5 % were co-doped.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.9-13
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• 2022

Bullets flying with a light from the back are called "tracers". Tracers are ignited by the combustion gas of the propellant and emit bright light that allows the shooter to visually trace the flight path. Therefore, tracers mark the firing point for allies to assist shooters to hit target quickly and accurately. Conventional tracers are constructed with a mixture of an oxidizing agent, raw metal, and organic fuel. Upon ignition, the inside of the gun can be easily contaminated by the by-products, which can lead to firearm failure during long-term shooting. Moreover, there is a fire risk such as forest fires due to residual flames at impact site. Therefore, it is necessary to develop non-combustion type luminous material; however, this material must still use the heat generated from the propellant, so-called "thermoluminescence (TL)". This study aims to compare the TL emission of Dy³⁺, La³⁺ and Ho³⁺ doped MgB₄O₇ phosphors prepared by solid state reaction. The crystal structures of samples were determined by X-ray diffraction and matched with the standard pattern of MgB₄O₇. Luminescence of various doses (200 ~ 15,000 Gy) of gamma irradiated Dy³⁺, La³⁺ and Ho³⁺ (at different concentrations of 5, 10, 15 and 20 %) doped MgB₄O₇ were recorded using a luminance/color meter. The intensity of TL yellowish (CIE x = 0.401 ~ 0.486, y = 0.410 ~ 0.488) emission became stronger as the temperature increased and the total gamma-ray dose increased.

• Fire Science and Engineering
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• v.33 no.4
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• pp.59-69
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• 2019

The present article relates to an experimental study on fire risks due to overcharge and external heat of ESS lithium battery. According to the experimental results of overcharge, ignition occurred as combustible gas and smoke was slowly increased after occurrence of venting, and an explosive combustion form accompanied by flame eruption and sparks was displayed as charged energy is rapidly discharged in an instant. On the other hand, according to the experimental results of external heat, as a tremendous amount of combustible gas and smoke was ignited following being discharged after occurrence of vent, the charged energy itself was rapidly reduced due to the discharged energy so that a passive combustion form was observed when compared with overcharge after occurrence of flames. According the analysis results of fire damage characteristics, differences between external heat (External flame) could be found through visual and X-ray inspections. Namely, while inside electrode plate was completely destroyed and perforation of the electrode plate was observed in the case of overcharge, fire damage of the electrode plate was not severe maintaining the form in the case of external heat.

• Journal of the Mineralogical Society of Korea
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• v.22 no.2
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• pp.153-162
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• 2009

The main compositions of "Seokganju", a Korean traditional red mineral pigment, are iron oxides. To investigate its mineralogical and functional properties, we had got its ore from Juto cave in Ulreoung island, which was a famous field of it in Korean documents. The ore occurs as a paleosol between the olivine basalt and amphibole trachyte in discontinuously. It is reddish brown and yellowish brown and consists mainly of clay minerals with minor debris. Its reddish and yellowish brown color are due to the hematite and ferrihydrate, respectively. These iron oxides are precipitated as ferrihydrate from the ferrous water in the paleosol and partly changed to hematite. The color reproduced in timber by using seokganju pigment with traditional tools and methods is similar to that in heritage building. The moistureproofing and fire resistance of Ulreungdo seokganju is far better than that of artificial seokganju. Moreover, the combustion tests show that the artificial seokganju promote the ignition and combustion of the timber. Ulreungdo seokganju is regarded as a pigment with fungicidal efficacy because growth of two wood decay fungi (cov. and typ.) are inhibited in solid medium with it.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.49-57
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• 2013

Recently, recycling of industrial by-products and CO2 reduction have been important issues in the world. In this reason, applications and reuse of Fly ash as a binder for concrete, which is generated in thermoelectric power plant, have been one of the effective recycle methods. In order for Fly ash to be applied to concrete, Korean Standard(KS) has selected and managed quality such as $SiO_2$, fineness, specific gravity, ignition loss and activity index. However, there is a limits for activity index, whose test period required is at least 28 days or 91 days. Activity index is the critical indication standard to determine mechanical strength of concrete that contained Fly ash. To complement the disadvantage of test method, this research provided "API test method", which quickly measure Pozzolanic reaction of Fly ash can be considered as a alternative of activity index. Then, the adaptable API test method need to be investigated through comparative analysis with the test result of API, activity index and K-value. The test method can make evaluation of Fly ash quality faster and more accurate. As a result, most Fly ash produced in Korea has not been satisfied in the KS quality standard except water content and specific gravity, and especially fluidized bed boiler ash has its characteristics. Also, API, activity index and K-value have superior interrelationship. The interrelationship between API and activity index and K-value gets increased as the material age gets higher, so API test can be considered as very useful test method for Pozzolanic reaction evaluation of Fly ash.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.59-66
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• 2018

Using hydrogen fuel is expected to be suitable as a reciprocating internal combustion engine with heightened interest in HALE(High Altitude Long Endurance) UAV(Unmanned Aerial Vehicle). Hydrogen is hightest energy density per mass so it can continue to charge for long periods of time and have positive part of the environmental effects. However, it is estimated that there is less research on hydrogen fuel engine currently applied, and many studies need to be done. Depending on the operation, there are factors that result in supercooling due to reduced radiation or reduce cooling performance due to low air density. Therefore, the experiment was to change the temperature of the cooling water and investigate the effect on engine combustions. The limitation of the stable operation range due to backfire is dominated by the excess air ratio rather than the effect of the cooling water temperature change. When the cooling water temperature increases, the volumetric efficiency decreases and the torque decreases. As the cooling water temperature decreases, the heat loss was increased and consequently the thermal efficiency was decreased.