• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.77-77
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• 2013

최근의 산업활동에서는 신규 원료 개발과 생산 효율성을 높이기 위하여 분체 공정이 증가하고 있는데, 미세 분진의 취급으로 분진운의 형성과 착화가 용이해지므로 분진폭발이나 화재 위험성이 증가하고 있다. 분진을 안전하게 사용하고 저장, 취급하기 위해서는 착화 전의 위험성 지표로서 최저발화온도(MIT ; Minimum Ignition Temperature)를 사전에 파악해 두는 것이 중요하다. 분진농도의 발화온도는 장치 내의 발화위험성이나 분진 취급 공정의 사고예방대책 관리를 위한 실용적 관점에서 중요하게 활용되는 폭발특성값이다. 또한 분진의 발화온도는 분진농도에 의존하며 농도변화에 따른 가장 낮은 온도를 MIT라고 한다. 본 연구에서는 화재폭발사고 빈도가 줄지 않고 있는 Mg 및 Mg-Al합금(60:40 wt%, 50:50 wt%, 40:60 wt%)을 대상으로 조성비율에 따른 최저발화온도를 실험적으로 조사하였다. Mg 및 Mg-Al(60:40 wt%), Mg-Al(50:50 wt%), Mg-Al(40:60 wt%) 시료의 평균입경은 142, 160, 151, $152{\mu}m$이다. MIT실험장치는 IEC 61241-2-1(Methods for Determining the Minimum Ignition Temperatures of Dust, 1994)에 준거하여 제작하여 사용하였다. 실험장치는 가열로, 분진운 시료홀더, 온도조절장치, 압축공기 제어장치 등으로 구성되어 있다. 구체적인 실험방법은 시험분진를 분진홀더에 장착하고 0.5 bar의 압축공기를 0.3 sec 동안 사용하여 일정 온도로 가열된 로의 내부로 분진운을 부유시킬 때에 분진운이 발화하여 가열로 하단부의 개방구에까지 화염이 전파하는지를 디지털비데오카메라로 기록, 평가하여 발화 유무를 판정하였다. Mg합금에 대한 MIT를 측정한 결과 $740^{\circ}C$가 얻어졌으며, Mg-Al(60:40 wt%)의 MIT는 $820^{\circ}C$로 조사되었다. 그러나 Mg-Al(50:50 wt%) 및 Mg-Al(40:60 wt%)에 대해서는 최대 가열로의 설정온도를 $890^{\circ}C$까지로 하여 농도를 변화시키면서 조사하였으나 발화가 일어나지 않았다. 문헌에 따르면 Mg입자 표면의 산화피막은 다공성으로 일정 온도에서 산화반응이 시간에 따라 직선적으로 증가하는데 반하여, Al의 산화피막은 보호 작용을 하여 일정 온도에서 산화반응속도가 표면과 내부의 농도 기울기에 의한 확산속도에 의존한다고 보고하고 있다. 본 연구결과를 토대로 Mg-Al합금의 발화특성을 고찰해 보면, Mg-Al합금에서 자기 전파성이 작은 Al성분의 증가는 착화지연이 증가하여 연소성이 감소하여 최저발화온도의 증가로 이어지는 것으로 추정되었다. 또한 발화온도는 주어진 조건의 온도장에서 분진이 존재하는 시간 길이에 따라 변화하므로, 발화온도를 실험적으로 측정하는 경우에는 측정장치나 방법에 따라 달라지므로 사업장의 현장에 발화온도를 적용하는 경우에는 장치 내의 분진의 존재시간을 고려할 필요가 있다.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.474-478
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• 2018

For process safety, fire and explosion characteristics of combustible materials handled at industrial fields must be available. The combustion properties for the prevention of the accidents in the work place are flash point, fire point, explosion limit, and autoignition temperature (AIT) etc.. However, the combustion properties suggested in the Material Safety Data Sheet (MSDS) are presented differently according to the literatures. The accurate combustion properties are necessary to safely treatment, transportation and handling of flammable substances. In the chemical industries, n-ethylaniline which is widely used as a raw material of intermediate products and rubber chemicals was selected. For safe handling of n-ethyl aniline, the flash point, the fire point and the AIT were measured. The lower explosion limit (LEL)of n-ethylaniline was calculated using the lower flash point obtained in the experiment. The flash points of n- ethylaniline by using the Setaflash and Pensky-Martens closed-cup testers measured $77^{\circ}C$ and $82^{\circ}C$, respectively. The flash points of n-ethylaniline using the Tag and Cleveland open cup testers are measured $85^{\circ}C$ and $92^{\circ}C$, respectively. The AIT of the measured n-ethyl aniline by the ASTM E659 apparatus was measured at $396^{\circ}C$. The LEL of n-ethylaniline measured by Setaflash closed-cup tester at $77^{\circ}C$ was calculated to be 1.02 vol%. In this study, it was possible to predict the LEL by using the lower flash point of n-ethylaniline measured by closed-cup tester. The relationship between the ignition temperature and the ignition delay time of the n-ethylaniline proposed in this study makes it possible to predict the ignition delay time at different ignition temperatures.

• Fire Science and Engineering
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• v.27 no.5
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• pp.64-69
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• 2013

The autoignition temperatures (AITs) of solvent mixture was important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AITs and ignition delay time for n-propanol and formic acid system by using ASTM E659 apparatus. The AITs of n-Propanol and Formic acid which constituted binary system were $435^{\circ}C$ and $498^{\circ}C$, respectively. The experimental AITs of n-propanol and formic acid system were a good agreement with the calculated AITs by the proposed equations with a few A.A.D. (average absolute deviation). And n- Propanol and formic acid system was shown the minimum autoignition temperature behavior (MAITB).

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.225-231
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• 2021

Sesame seed oil cakes are classified as the animal or plant origin among the flammable liquids, and the fire occurs due to the spontaneous ignition through the accumulation of heat during the storage of residues after the extraction of sesame oil. In order to elucidate the cause of the spontaneous ignition of sesame seed oil cakes, the thickness (3 cm, 5 cm, 7 cm and 14 cm) of the sample container was varied, and the spontaneous ignition temperature was measured depending on the storage volume. Thus, the spontaneous ignition temperature was measured to be 180 ℃ at the thickness of 3 cm, 160 ℃ at 5 cm, 145 ℃ at 7 cm and 130 ℃ at 14 cm. As the thickness of the sample container increased, the critical ignition temperature decreased, and the induction time to spontaneous ignition and the time to reach the maximum temperature became longer. Furthermore, the apparent activation energy by the critical ignition temperature, which is the average temperature of ignition and non-ignition, was 97.10 [kJ/mol]. With these data, ignition characteristics of sesame seed oil cakes were determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.13-19
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• 2003

Mathematically simplified reaction scheme that simulates autoignitions of the end gases in spark ignition engines has been studied computationally. The five equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius preexponential constants, A, and heats of reaction for stoichiometric n-heptane/air, iso-octane/air, and their mixtures have all been optimised. The optimisation has been guided by Morley's correlation of the ratio of chain branching to linear termination rates with octane number. Comparisons between computed and experimental autoignition delay times have validated the Present simplified reaction scheme and the influences of octane number upon autoignition delay times have been computationally investigated. It has been found that both cool flame and high temperature direct reactions can have an effect on autoignition delay times.

• Journal of the Korean Institute of Gas
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• v.20 no.2
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• pp.16-22
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• 2016

Auto ignition characteristic is an important factor for handling combustible substance and fire prevention. This research studied about auto ignition characteristic and activation energy of Ethylene Glycol (EG) and Diethylene Glycol (DEG) by using ASTM D2155 type ignition temperature measuring apparatus. As the auto ignition temperatures, it was possible to get $434^{\circ}C$ for EG within sample amount range of $75{\sim}160{\mu}l$ and $387^{\circ}C$ for DEG within sample amount range of $130{\sim}150{\mu}l$. Also, it was possible to get $579^{\circ}C$ and $569^{\circ}C$ as instantaneous ignition temperatures with sample amount of $140{\mu}l$ for EG and DEG respectively. By using least square method from Semenov equation on measured ignition temperature and ignition delay time from this study, it was possible to calculate activation energy of EG as 25.41 Kcal/mol and DEG as 14.07 Kcal/mol. Therefore, it was possible to claim that DEG has more risk of auto ignition since the auto ignition temperature, instantaneous ignition temperature and activation energy of DEG is lower than EG.

• Journal of the Korean Society of Safety
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• v.21 no.3 s.75
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• pp.45-52
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• 2006

The AITs(autoignition temperatures) describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. The AITs are often used as a factor in determining the upper temperature limit for processing operations and conditions for handling, storage and transportation, and in determining potential fire hazard from accidental contact with hot surfaces. The measurement AITs are dependent upon many factors, namely initial temperature, pressure, volume, fuel/air stoichiometry, catalyst material, concentration of vapor, time lag. Therefore, the AITs reported by different ignition conditions are sometimes significantly different. This study measured the AITs of benzene, toluene and xylene isomers from time lag using AS1M E659-78 apparatus. The experimental ignition delay times were a good agreement with the calculated ignition delay times by the proposed equations wtih a few A.A.D.(average absolute deviation). Also The experimental AITs of benzene, toluene, o-xylene, m-xylene and p-xylene were $583^{\circ}C,\;547^{\circ}C,\;480^{\circ}C,\;587^{\circ}C,\;and\;557^{\circ}C$, respectively.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.180-187
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• 2011

본 논문은 다중이용업소와 목조건축물에 자주 사용되는 미송합판에 방염처리를 하여 유사 화재를 구현하고, 그 화염 세기에 따른 방염의 실효성을 실험한 것이다. 방염처리를 하면 화재 시 가연물의 초기착화시간을 지연시켜 화재성장속도를 늦출 수 있고, 원활한 소화활동을 가능하게 해준다. 하지만 어느 정도 화재가 진행되어 화염이 거세지면, 45도 연소시험을 통한 방염기준을 충족하여도 그 성능을 기대하기 어렵다고 한다. 따라서 45도 연소시험 시 사용되는 65mm의 불꽃보다 큰 화염상태(초기착화 이후의 상태)에서 방염처리한 내장재(미송합판)의 방염성능이 유지되는지의 여부를 실제로 입증하고 그 근거를 뒷받침하기 위하여 본 연구를 시작하게 되었다. 실험에서는 화재의 규모(화염의 세기)를 달리하여 각기 다른 종류의 방염제로 방염 처리한 미송합판의 착화 시 화염온도, 복사열 유속 그리고 착화지연시간을 파악하였으며, 45도 연소시험과 관련하여 방염성능을 분석하였다. 45도 연소시험의 경우 실험에 사용한 방염 처리 합판은 방염성능 기준을 만족하는 것으로 나타났으며, 소규모 유사 화재로 직경 10cm 연소용기를 사용한 연소실험에서는 방염 처리한 합판의 착화지연시간이 평균적으로 대규모 유사 화재실험보다 길어 어느 정도는 방염효과를 갖는 것으로 나타났다. 하지만 대규모 유사 화재로 1단위 유류화재 연소용기를 사용한 연소실험의 경우 열방출율이 커 형성된 탄화막이 무분별하게 박리되고 발화가 일어나 착화지연시간의 차이를 구별하기 어려웠기 때문에 방염효과를 기대할 수 없었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.757-758
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• 2023

시나브로는 언어발달지연 개선을 목적으로 발음을 교정하는 프로그램이다. TTS·STT API 를 사용하여 단어의 표준 발음을 음성 자료로 게시하고, 연습 후 사용자가 녹음한 음성에 대해 텍스트 및 시각 자료를 제공한다. 이를 통해 사용자는 자신의 발화 발음에 대해 객관적으로 피드백을 받아들일 수 있다. 시나브로는 전문기관 방문을 동반하는 일반적인 치료 방식과 달리, 온라인 기반 웹 서비스로 제작되어 공간, 시간, 비용 등의 제약을 극복하며 높은 접근성을 제공한다.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.8-15
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• 2012

For the safe handling of isopropyl alcohol, the explosion limits were investigated. The lower flash points, upper flash points, fire point, and AITs(autoignition temperatures) by ignition time delay for isopropyl alcohol were experimented. By using literature data, the lower and upper explosion limits of isopropyl alcohol were recommended as 2.0 and 12.0 vol%, respectively. The lower flash points of isopropyl alcohol were experimented $12{\sim}14^{\circ}C$ by using closed-cup tester and $18{\sim}19^{\circ}C$ by using open cup tester. And the upper flash points of isopropyl alcohol was experimented $38^{\circ}C$ by using Setaflash closed-cup tester. This study measured relationship between the AITs and the ignition delay times by using ASTM E659 apparatus was $463^{\circ}C$.