• Title/Summary/Keyword: 발화점

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Comparison of Partial Least Squares and Support Vector Machine for the Autoignition Temperature Prediction of Organic Compounds (유기물의 자연발화점 예측을 위한 부분최소자승법과 SVM의 비교)

  • Lee, Gi-Baek
    • Journal of the Korean Institute of Gas
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    • v.16 no.1
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    • pp.26-32
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    • 2012
  • The autoignition temperature is one of the most important physical properties used to determine the flammability characteristics of chemical substances. Despite the needs of the experimental autoignition temperature data for the design of chemical plants, it is not easy to get the data. This study have built and compared partial least squares (PLS) and support vector machine (SVM) models to predict the autoignition temperatures of 503 organic compounds out of DIPPR 801. As the independent variables of the models, 59 functional groups were chosen based on the group contribution method. The prediction errors calculated from cross-validation were employed to determine the optimal parameters of two models. And, particle swarm optimization was used to get three parameters of SVM model. The PLS and SVM results of the average absolute errors for the whole data range from 58.59K and 29.11K, respectively, indicating that the predictive ability of the SVM is much superior than PLS.

A Study on the Fire Safety of the several Oils for the Vehicles (차량용 오일의 화재안전성에 관한 연구)

  • Lee, Hae Pyeong;Park, Young Ju;Lee, Seung Chul;Kim, Hae Rim
    • 한국방재학회:학술대회논문집
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    • 2011.02a
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    • pp.194-194
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    • 2011
  • 현대 사회에서 차량을 비롯한 선박, 항공기와 같은 각종 수송수단들은 그 용도와 형태도 다양하고 널리 보급되어있을 뿐만 아니라 각 분야에서 없어서는 안 될 필수품이 되어 있다. 그러나 수송수단의 수와 활용빈도수가 증가함에 따라 그로 인한 차량화재, 선박화재 그리고 항공기화재 등과 같은 특수화재의 발생에 따른 재산 및 인명피해의 문제점들도 함께 늘어나고 있는 실정이다. 2009년 기준, 1년 동안의 전체 화재발생건수 47,071건 가운데 차량화재의 발생건수가 5,958건으로서 전체의 12.6% 정도를 차지하였다. 그뿐만 아니라 차량 내장재의 주 재질은 가연성을 지닌 열가소성 합성수지들로서 화재가 발생하였을 경우, 다량의 가연성 가스 및 독성가스를 방출하기 때문에 인명 및 재산 피해를 증가시키는 문제점을 갖고 있다. 하지만 아직까지도 이와 같은 수송수단에 대한 화재를 예방하거나 피해를 최소화할 수 있는 화재진압대책 등에 관한 연구는 미흡한 실정이다. 따라서 본 연구에서는 이러한 문제점을 해결하고 과학적이며 체계적인 대응방안을 수립하기 위한 기초 자료를 확보하고 이를 통한 수송수단의 화재안전성을 분석하고자 각종 수송수단에서 사용되는 오일을 대상으로 연소특성 분석 및 화재하중에 관한 연구를 수행하였다. 분석 대상 오일은 연료용과 부속용 오일로 크게 분류되며, 연료용 오일로는 차량용 경유와 휘발유 그리고 군용차량용 경유, 항공기용 백등유와 제트유, 선박용 고유황경유 등을 선정하였다. 부속용 오일로는 브레이크오일, 파워오일, 엔진오일, 자동변속기오일, 수동변속기오일을 대상으로 각각 일반용과 고급형 2가지씩 시료를 선정하여 분석을 수행하였다. 분석방법은 대상오일들의 기초물성을 고찰하기 위해서 비중계를 이용하여 각 시료들의 비중을 측정하였으며, 문헌으로부터 끓는점, 어는점 및 점도 등을 조사하였다. 또한, 대상오일들의 착화특성을 살펴보고자 콘칼로리미터와 인화점 측정기 및 발화점 측정기 등을 이용하여 발열량, 착화시간, 발연량, 발화점, 인화점 등을 측정하였다. 대상오일들의 물성 및 착화특성에 대한 측정결과를 살펴보면, 비중은 $725.8{\sim}1072.0kg/m^3$ 정도의 값을 나타냈고, 인화점은 영하의 인화점을 갖는 휘발유의 경우, 장비의 특성상 분석이 곤란하여 측정하지 못하였으며, 다른 시료들은 $45.3{\sim}266.6^{\circ}C$정도의 값을 나타냈다. 발화점은 $325.7{\sim}600.6^{\circ}C$정도의 값을 갖는 것으로 나타났다. 따라서 이와 같은 결과들을 활용하면 차량, 선박, 항공기 등에 대한 화재발생과 관련된 화재안전성을 분석하고 이를 통한 수송시스템의 화재에 대한 예방 및 대응 방안의 효율성을 높일 수 있을 것으로 생각된다.

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Radiolysis of Paraffin Encapsulation Wax (파라핀 고화체의 방사선적 가수분해)

  • Kim, Chang-Lak;Lee, Myung-Chan;Park, Won-Jae;Suk, Tae-Won;Burns William G.
    • Journal of Radiation Protection and Research
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    • v.20 no.4
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    • pp.237-243
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    • 1995
  • An estimate is made on the potential generation rate of H: from radiolysis of the Paraffin-wax encapsulant Proposed for the solidified liquid concentrate wasteform. The results show that the radiolytic Production of $H_2$ from paraffin-wax-encapsulated waste is dominated by the radiation energy released from $^{60}Co$. The radiolytic production of $H_2$ will proceed at an initial rate equivalent to aproximately $4.4{\times}10^2cm^3yr^1$ in 200 litre drums that are partly filled with 120 litres of encapsulated waste. The gas production rate will fall to a value of $7.2cm^3yr^1$ after 100 years. The lower flammable limit for $H_2$ in air will be reached in about 25 years and the lower explosive limit for $H_2$ in air would not be reached in 1000years. The timescale in which these safety-related limits are reached is strongly dependent on the level of filling of each waste drum. A reduction of the air space inside each drum would reduce the time required to reach the lower flammable limit.

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The Cause of Fire from Incomplete Electric Contact and Identifying It (불완전 접촉에 의한 발화원인 및 식별방법에 관한 연구)

  • Choi, S.B.
    • Journal of Korean Institute of Fire Investigation
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    • v.11 no.1
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    • pp.9-22
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    • 2008
  • We identified objectively the ignition spot of real fire scene and electrical machinery and appliances in sections which were acted for fire cause. By pointing out the actual condition of dealing electronic devices and researching the way of solution, I will presents the fundamental materials which will help to prevent recurrence.

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The Measurement of Combustible Characteristics of n-Undecane (노말언데칸의 연소특성치의 측정)

  • Ha, Dong-Myeong
    • Fire Science and Engineering
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    • v.27 no.2
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    • pp.11-17
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    • 2013
  • For the safe handling of n-undecane, the lower flash points and the upper flash point, fire point, AITs (auto-ignition temperatures) by ignition delay time were experimented. Also lower and upper explosion limits by using measured the lower and upper flash points for n-undecane were calculated. The lower flash points of n-undecane by using closed-cup tester were measured $59^{\circ}C$ and $67^{\circ}C$. The lower flash points of n-undecane by using open cup tester were measured $67^{\circ}C$ and $72^{\circ}C$, respectively. The fire point of n-undecane by using Cleveland open cup tester was measured $74^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659 apparatus for n-undecane. The experimental AIT of n-undecane was $198^{\circ}C$. The estimated lower and upper explosion limit by using measured lower flash point $59^{\circ}C$ and upper flash point $83^{\circ}C$ for n-undecane were 0.65 Vol.% and 2.12 Vol.%.

Training Effect on the Perception and Production of English Grapheme by Korean Learners of English (한국 학생들의 영어 철자 인지와 발화에 대한 훈련효과)

  • Cho, Mi-Hui
    • The Journal of the Korea Contents Association
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    • v.19 no.11
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    • pp.226-233
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    • 2019
  • Given that English grapheme is realized as five different American English vowels [ʌ, ju, ʊ, u, ə], the purpose of the current study is to examine Korean learners' perception and production of English grapheme and training effect on words with . Thus, the current study conducted pretest, training, and posttest for 31 Korean university students on 24 English words with . The overall results showed that the participants' perception and production accuracy was significantly improved in the posttest, thus indicating training effect on both perception and production. However, it was not the case that all five different vowels demonstrated training effect. In perception the accuracy rates of [ʌ], [ju], and [ə] were improved after training whereas those of [ʊ] and [u] were not. In production [ʌ], [ʊ], and [u] did not show training effect. These results indicate that the Korean participants had difficulty distinguishing between tense [u] and lax [ʊ] both in perception and production. In particular, the Korean participants tended to replace lax [ʊ] with tense [u] in production. This is because tense [u] is the best match to Korean [u] in acoustic measurements, so that tense [u] is easy for the Korean participants to pronounce than lax [ʊ]. Also, English [ʌ] tended to be mispronounced as [u]-quality vowels such as [u] and [ju], which is due to the spelling . The Korean participants also showed errors which insert [j] after alveolars [t, d, n, s], which runs against yod-dropping in American English. They also deleted [j] after labials and velars, which is due to the absence of orthography in the target words. Finally, pedagogical implications were discussed based on the findings of the current study.

A Study on the Risk of Spontaneous ignition to Butadiene Popcorn Polymer (Butadiene Popcorn Polymer의 자연발화 위험성에 관한 연구)

  • Koo, Chae-Chil;Lee, Jung-Suk;Choi, Jae-Wook
    • Fire Science and Engineering
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    • v.33 no.2
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    • pp.1-8
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    • 2019
  • This study was conducted to investigate the possibility of spontaneous ignition in Butadiene popcorn polymer, which is used as raw material and product in a chemical plant. A component analysis, thermogravimetric analysis, thermal stability analysis, spontaneous ignition point measurement and accelerated velocity calorimetric analysis were performed. As a result of analysis, various kinds of flammable components were measured and thermogravimetric analysis showed a weight loss of 95.6% in air and 89.2% in nitrogen. As a result of the thermal stability analysis, heat generation started at $88^{\circ}C$ in the air atmosphere, and the heat generation rate increased sharply in the vicinity of the natural ignition point ($220^{\circ}C$). The heat generation started at about $70^{\circ}C$ in nitrogen atmosphere, and the two exothermic peak values were observed up to $450^{\circ}C$. As a result of accelerated rate calorimetry, there was no exothermic phenomenon, and the lowest ignition temperature was $211.7^{\circ}C$ as a result of analysis of natural ignition point. Based on the results obtained from the thermal stability evaluation, it is considered that the possibility of inducing the thermal deformation of the column by the heat of reaction is sufficient.

Perception and Production of English Grapheme <a> by Korean Students (한국 학생들의 영어 철자 <a> 인지와 발화)

Relation between Perception and Production of English Vowels by Phonetic Training (음성 훈련에 따른 영어 모음의 인지와 발화 관계)

  • Jeong, Soon-Yong;Cho, Mi-Hui
    • The Journal of the Korea Contents Association
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    • v.15 no.2
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    • pp.542-551
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    • 2015
  • The purpose of this study is to examine how Korean college students perceive and produce American English vowels /i, ɪ, eɪ, ${\varepsilon}$, ${\ae}$, ${\alpha}$, ɔ, oʊ, ʊ, u, ʌ/ embedded in CVC words, and further to examine the relationship between perception and production of the target vowels. Forty-two participants who are English major/double major were divided into 2 groups under different conditions: the control group took only theoretical lessons about English phonetics and the experimental group took 4-week phonetic training lessons in addition to the theoretical ones. The result of the pretest revealed that the two groups showed strong correlations between perception and production. However in the post-test, both of the two groups had no correlation between the two elements. The two groups showed changes in the correct percentage in the post-test and this had the influence on the correlations between perception and production. The control group showed the fluctuation in perception, whereas the experimental group showed improvement in production, and these changes in the post-test had an influence on the correlations between perception and production. Based on this analysis, pedagogical implications were discussed and limitations of the study were also described.

Pitch and Rhythm of Rhyme for Rap Music Appreciation (랩 음악 각운의 음고와 박자)

  • Jeung, Mi-Sun;Lee, Chung-Min
    • Proceedings of the Korean Society for Cognitive Science Conference
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    • 2005.05a
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    • pp.239-243
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    • 2005
  • 랩 음악은 음악의 특성과 발화 언어의 특성을 가지고 있으며 음악적 특징을 가진 시와도 공통점을 가진다. 이러한 유사성을 근거로 Eminem이라는 랩 가수의 freestyle음악을 음성분석 프로그램을 사용하여 분석하였다. 대상 음악이 즉석적인 발화였음에도 불구하고 각운 부분에서의 피치(pitch)와 리듬은 매우 유사한 값을 보였다. 분석 결과에서 보여준 약간의 차이 값은 인간의 지각 능력과 성향을 고려하여 봤을 때 같은 피치(pitch) 같은 리듬으로 지각하기에 충분하다고 결론 내렸다.

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