• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.464-471
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• 1997

Convective smoke spread in a corridor is experimentally investigated using thermocouples and visualization technique with a laser beam sheet. The speed of smoke front under a ceiling is measured by a series of thermocouples. Visualization of the ceiling jet formation and of smoke filling process is carried out to observe the lowering of a smoke layer. From the results, a large-scale convective motion plays dominant roles for smoke spread in the vicinity of the end of the corridor from visualized photos along with temperature records. The large-scale convective motion of the smoke is generated from the impingement of the ceiling jet front on the end of the corridor, and thus turning the flows toward the floor. Such a circulating motion of fluid transports some smoke to some region where its momentum is effective. It is therefore shown that the conventional concept of lowering smoke in the two-layer zone model has some restrictions for the corridor because the lowering of smoke layer has been thought to be mass transport due to relatively small scale motions such as the decrease of buoyancy, mass diffusion and momentum exchanges.

• 한국연초학회지
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• 제29권1호
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• pp.14-22
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• 2007

This study was conducted to investigate the effect of the total sugar contents on chemical, smoke and sensory properties and to estimate the desirable chemical composition contents from sensory properties in flue-cured leaf tobacco. The leaves used in the study were in 2005 and in $1997{\sim}2006$ crop year. Nicotine and total nitrogen contents, filling value, impact, irritation and bitterness were reduced with increasing the total sugar contents of B2O(leaf) and C2L(cutters), whereas tar and CO contents and puff number were increased. The desirable sugar contents estimated from the best overall tobacco taste of smoke were 25.9% in B2O and 26.9% in C2L. All of regression equations among total sugar/nicotine ratio, total sugar, nicotine and total nitrogen contents were significant($p{\leqq}0.05$). There were no significant difference between the 4 grade(A2O, B2O, C2L, D2L) average and the whole plant(12 grade) average contents in total sugar, nicotine and total nitrogen contents. All of regression equations between the ratio of each grade content to the average content of twelve grades and stalk position[number ; from bottom(1) to top(12)] in total sugar, nicotine and total nitrogen contents were significant($p{\leqq}0.05$). The estimated desirable chemical properties which based on the best overall tobacco taste were 23.2% of total sugar, 2.39% of nicotine, 9.7 of total sugar/nicotine ratio, 2.57% of total nitrogen, 1.08 of total nitrogen/nicotine ratio in average of four grades. With decrease the total sugar content from 32.0% to 24.0%, filling value was enhanced by 14.1% in average of B2O and C2L, also tar and CO contents of smoke were decreased by 13.2% and 10.5%, respectively. These results suggest that the estimated desirable chemical composition contents may be useful to produce good leaf tobacco, and to enhance filling value and to reduce tar and CO contents of smoke in flue-cured leaf tobacco.

• 한국안전학회지
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• 제13권1호
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• pp.70-76
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• 1998

The smoke filling process for the atrium space containing a fire source is simulated using two types of deterministic fire models : Zone model and Field model. The zone model used is the CFAST(version 1.6) model developed at the Building and Fire Research Laboratories, NIST in the USA. The field model is a self-developed fire field model based on Computational Fluid Dynamics(CFD) theories. This article is focused on finding out the smoke movement and temperature distribution in atrium space which is cubic in shape. A computational procedure for predicting velocity and temperature distribution in fire-induced flow is based on the solution, in finite volume method and non-staggered grid system, of 3-dimensional equations for the conservation of mass, momentum, energy, species and so forth. The fire model i. e. Zone model and Field model predicted similar results for the clear height and the smoke layer temperature.

• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1485-1496
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• 2002

In order to investigate the fire-induced smoke movement in a three-dimensional room with an open door, numerical and experimental study was performed. The center, wall, and corner fire plumes for various sized fires were studied experimentally in a rectangular pool fire using methanol as a fuel. The numerical results from a self-developed SMEP (Smoke Movement Estimating Program) field model were compared with experimental results obtained in this and from literature. Comparisons of SMEP and experimental results have shown reasonable agreement. As the fire strength became larger for the center fires, the air mass flow rate in the door, average hot layer temperature, flame angle and mean flame height were observed to increase but the doorway-neutral-planeheight and the steady-state time were observed to decrease. Also as the wall effect became larger in room fires, the hot layer temperature, mean flame height, doorway-neutral-planeheight and steady-state time were observed to increase. In the egress point of view considering the smoke filling time and the early spread of plume in the room space, the results of the center fire appeared to be more dangerous as compared with the wall and the corner fire. Thus it is necessary to consider the wall effect as an important factor in designing efficient fire protection systems.

• 한국화재소방학회논문지
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• 제11권4호
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• pp.3-14
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• 1997

The smoke filling process for the atrium space containing a fire source is simulated using two types of deterministic fire model : Zone model and Field model. The zone model used is the CFAST(version 1.6) model developed at the Building and Fire Research Laboratories, NIST in the USA. The field model is a self-developed frie field model based on Computational Fluid Dynamic (CFD) theories. This article is focused on finding out the smoke movement and temperature distribution in atrium space which is cubic in shape. For solving the liked set of velocity and pressure equation, the PISO algorithm, which strengthened the velocity-pressure coupling, was used. Since PISO algorithm is a time-marching procedure, computing time si very fast. A computational procedure for predicting velocity and temperature distribution in fire-induced flow is based on the solution, in finite volume method and non-staggered grid system, of 3-dimensional equations for the conservation of mass, momentum, energy, species and so forth. The fire model i.e Zone model and Field model predicted similar results for clear heights and the smoke layer temperature.

• 한국화재소방학회논문지
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• 제13권1호
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• pp.21-30
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• 1999

본 연구는 세 가지 유형의 아트리움 공간에 대해서 Zone 모델과 Field 모델을 비교하였으며, Zone 모델로는 FIRST, CFAST, NIST에서 개발된 CCFM.VENTS 그리고 CSIRO에서 개발된 NBTC 1-room 모델을 사용하였고 Field 모델로는 Chow에 의해 개발된 화재모델과 본 연구에서 개발된 SMEP을 사용하였다. 두 모델들에 대한 비교는 서로 유사한 결과를 보였으며, 특히 PISO 알고리즘을 사용한 SMEP의 경우가 SIMPLER 알고리즘이 적용된 field 모델에 비해 더 빠른 계산시간을 보여 주었다.

• 한국화재소방학회논문지
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• 제13권4호
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• pp.20-29
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• 1999

본 연구는 두 가지 유형의 아트리움 공간에 대해서 Zone모델과 Field모델을 비교하였으며 특히 천장에 열 유속을 갖는 아트리움 화재에 대해서 SMEP화재 모델을 적용하여 연기거동을 수치해석 하였다. Zone 모델로는 NIST에서 개발된 CFAST 그리고 CSIRO에서 개발된 NBTC 1-room 모델을 사용하여 SMEP Field모델을 검증하였다. PISO 알고리즘과 부력항을 포함한 수정 k-e epsilon 난류모델을 사용한 SMEP은 연속, 운동, 에너지 그리고 농도 방정식을 풀었으며, 상용 Zone 모델들과의 비교는 서로 유사한 결과를 보였다. 천장이 유리로 만들어진 아트리움의 경우, 태양열에 의한 천장 열 유속을 고려함으로써 좀더 실제적인 화재현상을 규명할 수 있다. 수치해석결과 천장 열 유속 조건은 연층의 온도 분포에는 영향을 미치지만 연기의 하강과 거동에는 커다란 영향을 미치지 않고 있음을 확인 할 수 있었다. 따라서 화재 감지기나 배연 설비 시스템의 설치시 이러한 점들이 고려되어야만 한다.

• 한국터널지하공간학회 논문집
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• 제6권2호
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• pp.129-139
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• 2004

터널의 환기설계에 관련하여 종류식과 횡류식의 환기용량의 산정을 위해서 필요한 제반 가정들을 검토하였고, 종류식 설계에서의 최종 값인 임계유속 산정을 위한 몇 가지의 공식을 분석하였다. 이를 토대로 특정 공식을 개선하기 위한 방안을 실험결과를 토대로 제시하였다. 횡류식 설계에서 국제적으로 사용되고 있는 용량산정에 관한 지침은 화재공학적 의미가 전혀 없으며 관행적으로 적용되어 온 것임을 알 수 있었다. 뿐만 아니라 기존의 횡류식 환기설계에는 설계개념조차 명확하지 않음을 입증하였다. 즉 횡류식 시스템에서는 종류식에서의 "연기의 역류 방지를 위한 최소 유속의 유지"라는 개념조차 없이 환기용량이 결정되어 왔으며, 이것은 터널의 화재환기가 오염물질의 환기로부터 시작되어 정확한 화재공학적 분석이 결여되었기 때문이다. 이러한 문제를 해결하기 위한 시도로 횡류식 환기의 설계개념으로서 연기전파거리와 연기축적을 제안하였다. 축소모델 터널을 이용하여 연기전파거리에 관한 실험결과를 제시하였고, 이를 이용하여 기존의 관행대로 설계된 유럽의 터널들에 적용하였을 때 안전성에 문제가 있음을 보였다.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1997년도 추계 학술논문발표회 논문집
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• pp.43-48
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• 1997

아트리움 공간에서 화재 발생시 연기 유동에 대하여 두 가지 형태의 화재 모델인 zone 모델과 field 모델을 이용하여 시뮬레이션 했다. 사용된 zone model은 NIST에서 개발된 CFAST(version 1.6) 모델이며 field 모델은 전산유체역학 이론을 바탕으로 자체 개발된 화재 모델이다. 본 연구는 정육면체 모양의 아트리움 공간에서 연기 유동과 온도 분포에 대하여 해석하고자 한다. 화재로 인해 야기된 유동에 대하여 속도장과 은도장을 예측하기 위한 계산 과정은 유한체적법 및 비엇갈림격자계를 이용하여 질량, 운동량, 에너지 및 성분 보존 방정식등에 대한 3차원 비정상상태 지배방정식을 사용했다. 수치해석 결과 zone 모델과 field 모델의 화재 모델에 의해 예측된 연기 층 평균 경계놀이와 상부 더운 연기 층의 평균 온도에 대하여 거의 유사한 결과를 얻었다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.353-360
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• 1997

The modeling on fire safety assessment for a tall and narrow atrium is carried out using a reduced and full scale atrium models based on the performances of flow behavior in and near comer fire and smoke ventilation system. The comer (or wall) effects on the flame behavior considering air entrainment into a flame was evaluated theoretically and experimentally. Temperature, upward velocity, inlet air velocity, and pressure difference between the atrium space and atmosphere were measured systematically in a reduced scale model. The performance of the modeling to estimate temperature rise and natural air ventilation volume was verified based on the experimental results. Smoke filling rate from a model fire source set at the center of a tall and narrow atrium is fastest in the other cases in which fire source set in or near a corner. This suggested that the centering of the fire source is acceptable as the fire source position to assess the fire safety design for a tall and narrow atrium.