• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.395-399
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• 2010

강구조 부재의 내화성능평가를 위한 비재하가열시험은 강재 허용온도로 평가되고 있으나, 강재의 허용온도 설정은 H형강 부재의 최대하중로 평가되는 한계용도와 고온에서의 강소재의 허용응력도 능력으로 설정되었으므로 실지 작용되는 강구조 부재의 하중조건과 다양한 부재의 종류 등의 관점에서 허용온도의 적용은 다소 불합리한 점이 있다고 판단된다. 따라서 본 연구에서는 강구조 건축물에서의 부재에 작용하는 하중에 따른 내화성능의 차이를 보이고 이에 따른 합리적인 내화성능 평가방법을 제안하고자 한다.

• Journal of Korean Society of Steel Construction
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• v.22 no.6
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• pp.581-588
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• 2010

Recently the requirements of the buildings built with structural steel were increased in terms of structural stabilities and fire resistance at severe fire conditions. To meet the building regulations of fire resistance, a fire design is needed. This is of a prescriptive method and a performance engineering based method. Recently a simple calculation method as one of performance based engineering method is very popular because of its ease for an application in building built with structural steel. But, in Korea the performance based engineering method is not allowed yet. Thus it is needed to make a guideline for the performance based engineering method. The purpose of this study is to establish the limit temperature derived from structural beams made with both a H-section and a H-section filled with concrete at the web and derived the limit temperatures from beams made with H-sections and found out that the limit temperatures from two kinds of specimens depended on the applied loads and the specimens filled with the concrete represented 3 hour fire resistance in the range of 80%, 60%, and 50% of the maximum load.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.225-235
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• 2023

Critical temperature for grain filling of three Korean japonica rice varieties was analyzed by late transplantation to induce a low temperature during grain filling period in a field study. The grain filling percentage (GFP) and grain dry weight (GDW) showed a sigmoid development for the first and second transplants in 2020 and first to third transplants in 2021. For the third transplant in 2020 and fourth transplant in 2021, the GFP and GDW reached a peak at 42 days after heading (DAH), and then decreased or remained unchanged. In non-linear regression analyses, 95% of the final GFP and GDW appeared at 49 - 62 DAH for the second transplant in 2020 and at 37 - 46 DAH and 30 - 36 DAH for the second and third transplants in 2021, respectively. At these time points, the critical seven-day moving temperature (7dMovT) was 8.4~9.4℃ for the second transplant in 2020 and 9.4~10.9℃ for the second and third transplants in 2021, depending on the grain filling traits and varieties of rice. The lowest 7dMovT was 8.4 - 8.7℃ in the three varieties. The observed lowest 7-day mean temperature (7dMT) accompanying increases in the GFP and GDW was 9.4 - 10.1℃, depending on the varieties in the third transplant of 2020 and fourth transplant of 2021. In the two transplants mentioned above, the highest 7dMT that showed no increase or decrease in grain filling traits was 8.7 - 9.1℃. The critical temperature for grain filling of japonica rice was 8.4 - 8.7℃ based on the 7dMovT and 9.1 - 9.4℃ based on the 7dMT. The previous 7dMT of 10℃ is recommended to determine the marginal harvest time for safe rice cropping since the temperature was the highest among the lowest temperature that accompanied an increase in grain filling traits.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.153-163
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• 2003

Performed here is a comparative assessment study for the generation of the pressure-temperature limit curve of the reactor vessel. A round robin problem is proposed using the data available in Korea and all organizations interested in the generation of the pressure-temperature limit curve are invited. The problems consisting of 12 cases for cool-down are solved and their results are compared to generate a reference solution for the reference problem, which will be useful in the evaluation of the generation of the pressure-temperature limit curve in the future.

• Journal of Korean Association for Spatial Structures
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• v.12 no.3
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• pp.55-62
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• 2012

본 연구는 온도 증가에 따른 압축을 받는 H형 강재의 플랜지와 웨브의 국부 및 전체좌굴응력 내화해석 프로그램 개발과 플랜지와 웨브가 항복파괴전에 국부좌굴이 일어나지 않을 한계 판폭두께비의 상관값을 구하는 프로그램을 개발하는 것이다. 고온에서의 강재의 응력-변형도 관계식은 EC3:Part 1.2를 근거로 하였으며, 비교, 검토를 위하여 영국 BS5950의 강재를 대상으로 온도 증가에 따른 압축을 받는 강재의 플랜지와 웨브의 파괴온도와 하중을 본 연구의 내화해석 프로그램으로 예측하였다. 본 연구는 좌굴 및 항복에 대한 내화해석 프로그램을 개발하는 것을 목적으로 하고 적용 예를 통하여 좌굴 및 한계 판폭두께비를 분석하고 개발 프로그램의 타당성을 검토하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.163-163
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• 2013

최근의 수많은 산업 현장에서 취급하고 있는 각종 화학물질은 잠재적 위험성이 크므로 보관, 수송 및 취급할 때 특별한 주의가 필요하다. 공정 설계 시 정확하지 않은 폭발한계를 사용함으로서 사고가 유발되는 경우가 많다. 따라서 사업장에서 사용되고 있는 화학물질의 화재 및 폭발 특성치인 인화점, 폭발한계 등을 정확히 파악하는 것은 중요하다. 인화점은 하부인화점과 상부인화점으로 나누고 있고 있으며, 인화점은 가연성 액체의 화재 위험성을 나타내는 지표로써, 가연성액체의 액면 가까이서 인화할 때 필요한 증기를 발산하는 액체의 최저온도 또는 점화원 존재시 인화가 일어날 수 있는 최저온도, 그리고 가연성증기의 포화증기압이 공기와 혼합기체의 폭발한계 하한농도와 같게 되는 온도로 정의한다. 폭발한계는 발화원이 존재할 때 가연성가스와 공기가 혼합하여 일정 농도범위 내에서만 연소가 이루어지는 혼합범위를 말한다. 본 연구에서는 실제 공정에서 사용되고 있는 n-Hexadecane의 인화점을 측정하여 이를 기존 문헌값과 비교 하였고, 측정된 인화점을 이용하여 폭발한계를 예측하였다. 예측된 폭발한계를 여러 문헌에 제시된 자료과 비교하여 공정안전에 타당한 자료를 제시하였다. 본 연구는 n-Hexadecane을 취급하는 공정에서 안전 확보의 중요한 지침 마련과 MSDS D/B의 최신화에 유용한 정보를 제공하는데 목적이 있다.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.75-81
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• 2011

For the safe handling of cyclohexane, the explosion limit at $25^{\circ}C$ and the temperature dependence of the explosion limits were investigated. Flash point and AIT(autoignition temperature) for cyclohexane were experimented. By using the literatures data, the lower and upper explosion limits of cyclohexane recommended 1.0 Vol% and 9.0 Vol%, respectively. Moreover lower flash points of cyclohexane recommended $-20^{\circ}C$. It was measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for cyclohexane, and the experimental AIT was $255^{\circ}C$. The new equations for predicting the temperature dependence of the explosion limits of cyclohexane is proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.7-13
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• 2006

In order to evaluate the fire and explosion involved and to ensure the safe and optimized operation of chemical processes, it is necessary to know combustion characteristics. The explosion limit, the heat of combustion, flame temperature and temperature dependence of the lower explosive limit are the major combustion characteristics used to determine the fire and explosion hazards of the flammable substances. The aim of this study is to investigate interrelationship of explosion characteristics and the temperature dependence of the lower explosion limit at elevated temperature for akylketones. By using the reference data, the empirical equations which describe the interrelationships of explosion properties of akylketones have been derived. Also, the new equations using the mathematical and statistical methods for predicting the temperature dependence of lower explosion limits of akylketones on the basis of the literature data are proposed. The values calculated by the proposed equations agreed with literature data within a few percent. From the given results, using the proposed methodology, it is possible to predict the explosion limits of the other flammable substances.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.213-218
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• 1994

제올라이트 분말을 기본재료로 하는 전기유변유체의 전기 및 유변학적 특성이 연구되었다. 전기장 인가시 높은 한계응력을 얻기 위하여 비교적 유전상슈가 큰 5종류의 유전유체를 선택하여 제올라이트 분말과 혼합하여 전기유변유체를 준비하였다. Couette형 rheometer를 이용하여 유변유체의 한계응력을 인가된 전기장 및 온도의 함수로서 측정하였다. 이중 chlorinate hydrocabon oil과 제올라이트 분말을 혼합한 전기유변유체의 한계응력은 6KPa(E=4KV/mm, T=$25^{\circ}C$)로서 최대치를 기록하였다. 측정된 한계응력은 온도가 상승하면 점차 감소하는 반면 전류밀도는 온도에 따라 증가하였다. 전류밀도에 대한 Arrhenius 그라프에서 전기전도에 대한 활성화 에너지는 약 0.7eV였으며 이는 제올라이트 분말에 포함된 $Na^{+}$ 이온의 확산에 기인하는 것으로 분석되었다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.246-261
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• 2023

We investigated critical temperature for early marginal transplanting (CT-EMT) of the contemporary japonica rice varieties in Korea through the field, pot seedling tray, and the phytotron experiments during 2020 to 2023. The lowest mean temperature for 10 days from transplanting (MT-10DFT) that resulted in earlier heading date was 12.4℃ and the highest MT-10DFT that did not show the earlier heading date was 12.0℃ in the field study when the MT-10DFT varied by changing transplanting date. The lowest MT-10DFT that induced the increased biomass but not the earlier heading date was 11.6℃ and the highest MT-10DFT that showed neither the increased biomass nor the earlier heading date was 11.4℃. Compared to the 10-day later transplanting, the dates of the first root development, initiation of the chlorophyll recovery, and the first tiller development were earlier when the MT-10DFT was 9.1℃ or higher, 10.5℃ or higher, and 11.6℃ or higher, respectively, in the pot seedling tray and field experiments. The earliness of the first tiller development was a practical index for the estimation of CT-EMT during the early growth stage of rice. The response of transplanted rice to temperature treatments with the diurnal change of 10℃ in the phytotron study was similar to that shown in the field study. The data shown for constant temperature without a diurnal change revealed that the extent of positive effects of high temperature at day-time was greater than the extent of negative effects of low temperature at night-time on the early growth of transplanted rice. It was concluded that the critical MT-10DFT for early marginal transplanting of japonica rice in the temperate environments was between 11.4 to 11.6℃ based on the plant growth and between 12.0 to 12.4℃ based on the plant development.