• Fire Science and Engineering
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• v.30 no.1
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• pp.12-16
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• 2016

Propane fires of 1000 to 3000 kW in the ISO 9705 fire room were simulated using FDS to study the problem of decreasing temperature with increasing fire size. A criterion is proposed for under-ventilated fires. The computed temperature at 2000 kW and above was lower than that at 1500 kW. The heat release rate was limited by a lack of oxygen in the simulation. It was found that the heat release rate can therefore be a criterion for under-ventilated fires in simulations. Fires of 1700 kW and above in the ISO 9705 fire room are predicted to be under-ventilated.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.96-96
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• 2000

화학증착법으로 증착된 다이아몬드 박막은 우수한 전기적 특성과 뛰어난 화학적, 열적 안정성 때문에 전계방출소재로 많은 관심을 불러 일으키고 있다. 다이아몬드 박막의 전계방출은 저전계에서 일어나는 것으로 알려져 있으며, 저전계방출의 원인을 규명하려는 많은 연구가 진행되어 왔다. 한편, 다이아몬드 박막의 전계방출전류는 금속기판의 사용에 의한 기판/다이아몬드 접촉의 개선, 다이아몬드 박막내의 흑연성분의 조절에 의한 구조변화, 보론이나 인 (P), 질소의 도핑, 수소 플라즈마나 cesium 등의 금속을 이용한 표면처리 등의 여러 방법에 의하여 향상된다는 것이 입증되었다. 그 외에 메탄과 대기 분위기 처리, 암모니아 분위기에서의 레이저 조사도 전계방출특성을 향상시키는 것으로 보고되었다. 그러나, 다이아몬드 박막의 성장후 구조적 특성이 다른 박막의 후성장이나 열분해된 운자수소 처리가 다이아몬드 박막의 전계방출특성에 미치는 영향에 관한 연구는 지금까지 이루어지지 않았다. 본 연구에서는 수소처리와 후성장이 다이아몬드 박막의 전계방출특성에 미치는 영향을 고찰하고 이로부터 그 원인을 규명하고자 하였다. 다이아몬드 박막은 hot-filament 화학증착법을 이용하여 증착하였다. 후성장한 다잉아몬드 박막내의 흑연성분과 박막의 두께를 체계적으로 조절하여 후성장 박막의 구조적 특성과 그 두께의 영향을 확인할 수 있었다. 후성장층내의 흑연성분과 두께가 증가할수록 전계방출특성은 향상되다가 저하되었다. 한편, 다이아몬드 박막을 성장시킨 후 수소분위기 처리를 함에 따라 전계방출특성은 향상되었지만 수소처리시간이 5분 이상으로 증가함에 따라 그 특성은 저하되었다. 본 연구에서는 수소처리와 후성장시 나타나는 전계방출특성의 변화 원인을 규명하고자 한다.기판위에서 polymer-like Carbon 구조는 향상되는 경향을 보였다.0 mm인 백금 망을 마스크로 사용하여 실제 3차원 미세구조를 제작하여 보았다. 그림 1에서 제작된 구조물의 SEM 사진을 보여주었으며, 식각된 면의 조도가 매우 뛰어나며 모서리의 직각성도 우수함을 확인할 수 있다. 이와 같이 도출된 시험 조건을 기초로 하여 리소그래피 후에 전기 도금을 이용한 금속 몰드 제작 및 이온빔 리소그래피 장점을 최대한 살릴수 있는 미세구조 제작에 대한 연구를 계속 추진할 계획이다. 비정질 Si1-xCx 박막을 증착하여 특성을 분석한 결과 성장된 박막의 성장률은 Carbonfid의 증가에 따라 다른 성장특성을 보였고, Silcne(SiH4) 가스량의 감소와 함께 박막의 성장률이 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 줄어들어 성장률이 Silane가스량에 의해 지배됨을 볼 수 있다. UV-VIS spectrophotometer에 의한 비정질 SiC 박막의 투과도와 파장과의 관계에 있어 유리를 기판으로 사용했으므로 유리의투과도를 감안했으며, 유리에 대한 상대적인 비율 관계로 투과도를 나타냈었다. 또한 비저질 SiC 박막의 흡수계수는 Ellipsometry에 의해 측정된 Δ과 Ψ값을 이용하여 시뮬레이션한 결과로 비정질 SiC 박막의 두께를 이용하여 구하였다. 또한 Tauc Plot을 통해 박막의 optical band gap을 2.6~3.7eV로 조절할 수 있었다. 20$0^{\circ}C$이상으로 증가시켜도 광투과율은 큰 변화를 나타내지 않았다.부터

• Fire Science and Engineering
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• v.26 no.5
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• pp.21-27
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• 2012

A real A real scale fire test was performed in accordance with KS F ISO 9705 test method to investigate the combustion characteristics of glass wool sandwich panels. To do this, six kinds of specimens having different density and thickness were examined. The glass sandwich panels were installed inside the room, which had internal dimensions of 2.4 m wide${\times}3.6m$ deep${\times}2.4m$ high. also, combustion characteristic are determined through the exposure of specimens to flame by the propane gas burner has a capacity of 100 kW (10 minutes) and 300 kW (10 minutes) for total 25 minutes of test time. Results of the real sale fire test, it was found that maximum HRR of each specimen was 333.2~365.5 kW, maximum heat flux was 12.4~12.9 kW/$m^2$ And, maximum internal temperature for all specimens was not over $500^{\circ}C$. During the real scale fire test, flash-over didn't occur and the difference by density and thickness of specimen was not found from the results of HRR, heat flux, and internal temperature measurement.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.478-485
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• 2015

The aim of this study is to analyze the combustion and thermal properties in order to establish baseline data for the fire safety evaluation of domestic timbers. The combustion properties such as heat release rate, total heat release, gas yield, and mass loss were analyzed by the method of cone calorimeter test and thermogravimetry (TGA). Thermal decomposition temperatures of the specimens by TGA were recorded as $359.83^{\circ}C$ for White pine, $359.80^{\circ}C$ for Red-Leaved Hornbeam, $363.14^{\circ}C$ for Carolina poplar, $358.59^{\circ}C$ for Konara oak, and $362.11^{\circ}C$ Sargent cherry. Red-Leaved Hornbeam showed the highest value of heat release rate, but, Carolina poplar wood showed the lowest value. In case of the total heat release, Red-Leaved Hornbeam wood showed the highest value and Carolina poplar wood showed the lowest one. The gas analysis results showed that Sargent cherry wood had the lowest value of 0.021, and Konara oak had the highest at 0.031 in the $CO/CO_2$. The minimum value of mass reduction was recorded as 87.57% for Sargent cherry, but, on the other hand, it was 95.03% for Konara oak. There was a correlation between the gas generation of CO and $CO_2$, and combustion behavior of woods. These results are expected to be usful for providing a fundamental guideline with the fire safety of wood use in interior applications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.21-26
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• 2003

In this research, the change of coefficient of thermal expansion (CTE) of graphite/epoxy composite laminate under space environment was measured using fiber optic sensors. Two fiber Bragg grating (FBG) sensors have been adopted for the simultaneous measurement of thermal strain and temperature. Low Earth Orbit (LEO) conditions with high vacuum, ultraviolet and thermal cycling environments were simulated in a thermal vacuum chamber. As a pre-test, a FBG temperature sensor was calibrated and a FBG strain sensor was verified through the comparison with the electric strain gauge (ESG) attached on an aluminun specimen at high and low temperature respectively. The change of the CTE in a composite laminate exposed to space environment was measured for intervals of aging cycles in real time. As a whole, there was no abrupt change of the CTE after 1000 aging cycles. After aging, however, the CTE decreased a Little all over the test temperature range. These changes are caused by outgassing, moisture desorption, matrix cracking etc.

• 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.

• Nuclear industry
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• v.20 no.6 s.208
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• pp.31-44
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• 2000

본 연구에서 액체금속로의 노심용융(core meltdown)으로 인한 초 즉발 임계(super-prompt critical)의 출력 폭주 사고시, 노심의 반응도 및 열수력 특성 변화와 에너지 방출량등을 계산하기 위하여, Bethe-Tait 방버론을 수정, 보완한 분석 모델이 개발되었다. 주요 보완 내용으로서는, 금속 연료 노심의 단상 액체 영역에서의 선형의(Linear) threshold 형태의 상태 방정식뿐만 아니라 포화 증기(saturated fuel vapor) 영역에서의 상태 방정식이 개발되었고, 이에 따른 노심 붕괴 반응도(disassembly reactivity)의 분석 모델이 개발되었다. 또한 도플러 반응도 효과를 고려하기 위한 분석모델도 아울러 개발되었다. 상기 보완 모델을 실행할 수 있는 수치 해석 프로그램이 개발되었고, 이를 활용하여 KALIMER에서 HCDA가 발생하였을 경우 노심에서의 에너지 방출량 계산이 수행되었다. 분석결과 도플러 효과와 포화 증기 영역에서의 압력 증가 및 노심팽창의 중요성이 확인되었다. 도플러 효과가 고려되지 않을 경우 HCDA는 분석된 모든 반응도 삽입률에 대하여 폭발적인 에너지 방출과 함께 사고가 종결되는 것으로 평가되었다. 그러나 도플러 상수가 최적 평가치인 -0.002인 경우 50$/s이하의 반응도 삽입률에서는 노심은 비등점(0.8KJ/g)에 도달치 않았으며, 설계 기준 사고인 100$/s의 경우에도 노심은 포화 증기 영역에 머물고 압력이 급격히 증가하는 단상(single phase)액체 영역의 threshold 값에 미치지 않기 때문에 사고는 핵연료 증기(vapor)의 점진적인 분산과 함께 종결되는 것으로 분석되며, 총 에너지 발생량은 약 1,800MJ로서 기계적 손상 에너지로 전환되는 분율을 고려할 때 KALIMER 원자로 용기의 구조 설계 기준치에 비해 상당한 여유도를 갖는 것으로 평가되었다.

• Fire Science and Engineering
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• v.25 no.3
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• pp.20-27
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• 2011

This paper studied combustion characteristics of the sponge type sound-absorbing materials extensively used on building interior. To estimate of the combustion characteristics, we carried out combustion experiment of general type and incombustibility type sound-absorbing materials. And then to evaluate the suitability of the sponge type sound-absorbing materials, we measured heat release rate (HRR) and smoke density (Ds) of the sound-absorbing materials using by a cone-calorimeter. From the combustion experimental results, general type sound-absorbing materials were rapid burned simultaneously with ignition and the incombustibility type sound-absorbing materials had all gone out simultaneously with ignition. Measured results of HRR and Ds were not satisfied KS F ISO 5660-1 and IMO FTP Code, form the results, the sponge type sound-absorbing materials were ill-suited for using building interior.

• Journal of the Korean Wood Science and Technology
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• v.40 no.1
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• pp.19-25
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• 2012

The fire retardant bamboo charcoal (BC) boards were manufactured for interior building materials in this study, The BC boards were manufactured by mixing and pressing of the bamboo charcoal, expanded vermiculite, and inorganic binder. The combustion behaviors of the BC boards were investigated using a cone calorimeter at an incident heat flux of 50 kW/$m^2$. Three building materials (plywood, BC board of Japan, and gypsum board) were used to observe the burning behaviors of weight loss, total heat release rate, and maximum heat release rate. Surface test and toxicity evaluation of the BC board were also conducted. The weight loss of the BC board (12.0%) was lower than the nonflammable gypsum board (15.6%) after burning of 10 min. Total heat release of the BC was 3 MJ/$m^2$ (KS standard 8 MJ/$m^2$) and total heat release rate of the BC was 20 kW/$m^2$ (KS standard 200 kW/$m^2$). Therefore, the BC boards were adjustable for the third-grade flame retardant building materials. External appearance change and mouse toxicity were not found in the BC boards after the combustion test.

• Fire Science and Engineering
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• v.33 no.3
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• pp.37-43
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• 2019

In this study, ethanol pool fire extinguishing experiments were conducted using a twin-fluid nozzle. Ethanol pool fires, 5.027×10^-3 ㎡ and 1.131×10^-2 ㎡ in size (80 mm and 120 mm in fuel pan diameter, respectively), were tested, and the flow rates supplied to the twin-fluid nozzle for fire extinguishing were 156-483 g/min and 20-70 L/min for water and air, respectively. The heat release rate increased with increasing fire source area, and heat release rates of 5.027×10^-3 ㎡ and 1.131×10^-2 ㎡ in size were measured to be 1.01 kW and 5.51 kW, respectively. For both fire source cases in the present experimental range, regardless of the water flow rates, the ethanol fires were extinguished successfully under the high air flow rate condition (e.g., above 40 L/min). On the other hand, under all water flow rate conditions, the fire extinguishing time and water consumption decreased with increasing air flow rate, which were approximately 23 s and 185 g under high air flow rate conditions (e.g., above 50 L/min), respectively. Based on the water consumption per heat release rate, the present experimental data were compared with the previous ones using a single-fluid nozzle, and it was found that the twin-fluid nozzle could extinguish a fire with a lower water consumption than a single-fluid one.