• 대한안전경영과학회지
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• 제19권1호
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• pp.9-13
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• 2017

In this study, the height of the flame required to estimate the heat flow path and flame spread in pool fire has been applied by the empirical formula, but it is calculated without applying the pressure and temperature parameters of the fire room. Until now, the height of the flame applied to pool fire was $l_F=0.235Q^{2/5}-1.02D$ in the Heskestad empirical formula, but accurate temperature calculation was not possible due to the temperature and pressure which are not influenced by the flame height. Therefore, applying the temperature and pressure around it can calculate the exact flame height, which can be applied to fire investigation and fire dynamics. The structure of the flame is divided into a continuous flame, an intermittent flame, and a buoyancy flame, but it is assumed that the flame height is calculated from the visual aspect to the intermittent flame region, and the temperature of the buoyancy flame is very low. The effect of heat of vaporization on the height of flame was investigated. The results showed that flame height was different according to the pressure and temperature around the fire room.

• 한국화재소방학회논문지
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• 제31권2호
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• pp.52-60
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• 2017

NUREG-1934에서 제시된 원자력발전소 주제어실의 케비닛 화재를 대상으로 운전원의 거주성을 평가하기 위하여 수치해석이 수행되었다. 이를 위해 본 연구에서는 대표적인 화재모델인 FDS가 사용되었다. 운전원의 거주성을 결정하는 기준으로서 복사 열유속, 상층부 온도, 연층높이 및 연기의 광학밀도뿐만 아니라, CO 등과 같은 독성물질의 농도가 포함되었다. 주요 결과로서, 화재모델의 확인 및 검증(V&V) 기반의 주요 입력인자 민감도 및 모델 불확실도 분석을 통해 다양한 화재시나리오에 대하여 거주성 기준의 초과 확률 및 거주 가능시간이 산출되었다. 최대 열방출률, CO 및 Soot yields의 민감도 분석을 통해, 거주시간 뿐만 아니라 거주성을 결정하는 한계기준의 변화가 발생됨을 확인하였다. 이러한 방법론은 불확실한 케비닛 화재정보를 이용한 주제어실의 거주성 평가의 신뢰성 강화를 위한 현실적인 대안이라 판단된다.

• The Korean Journal of Ecology
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• 제19권5호
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• pp.417-430
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• 1996

This study was conducted to investigate the developmental process of plant community during the secondary succession and the dynamics of soil properties in the burned and unburned areas of Mt. Ch’oly-san. Owing to the forest fire occurred on April, 1989, the red pine(Pinus densiflora) forest and its floor vegetation were burned down. The floristic composition of burned and unburned areas were composed of 53 and 49 species of vascular plants, respectively. The dominant species based on SDR4 of the burned sites were lespedeza cyrtobotrya (89.62), Miscanthus sinensis var. purpurascens (62.50), and Carex humilis (58.73), Quercus serrata (43.33). In contrast, Pinus densiflora (83.56), Lespedeza cyrtobotrya (55.57), Miscanthus sinensis var. purpurascens (51.88) and Carex humilis (50.41) were dominant in the unburned area. The biological spectra showed the $H-D_1-R_5-e$ type in both the burned and unburned areas. The indices of similarity ($CC_S$) between the two areas were 0.74. Degree of succession (DS) was 604 in the burned area and 802 in the unburned area. From these facts, it is assumed that the succession is rapidly progressing because of the recovery of vegetation. The species diversity ($\={H}$) and evenness index(C) in the burned and unburned areas were 0.15 and 0.18, respectively. Red pine tree did not resprout after scorch by the forest fire, but Lespedeza, Quercus, Rhododendron, Albizzia, and Zanthoxylum resprouted from the roots and trunks after the forest fire. It seems that these species are the fire-resistant species. Soil properties such as soil pH, content of organic matter, available phosphous, total nitrogen, tatal carbon, exchangeable potssium, sodium, calcium, and magnesium increased due to forest fire. These results suggest the intensity of forest fire in the study area was relatively weak. Monthly changes of soil properties were of little significance except for some cases.

• 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.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.84-96
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• 2022

In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3-0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

• 한국화재소방학회논문지
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• 제32권1호
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• pp.7-15
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• 2018

구획실 내 프로판 가스화재에 대해 Fire Dynamics Simulator (FDS)를 이용한 수치계산을 수행하고 실험과의 비교를 통해 적용된 연소모델 예측성능을 평가하였다. 검토된 연소모델은 FDS v5.5.3의 혼합분율 연소모델과 FDS v6.6.3의 Eddy Dissipation Concept (EDC) 모델이며, EDC 모델에서 화학반응기구는 1-step Mixing Controlled, 2-step Mixing Controlled, 3-step Mixing Controlled 및 Mixing Controlled 반응과 유한화학반응이 혼합된 3-step Mixed 반응을 적용하였다. 구획실 내부의 온도에 대해서는 각 연소모델들 간의 예측성능 차이는 그다지 크지 않음을 확인하였다. 연소모델 차이에 의한 $O_2$와 $CO_2$ 농도에 대한 예측성능 차이보다는 CO에 대한 예측결과 차이가 크게 나타났다. CO 농도에 대해서는 EDC 3-step Mixing Controlled 모델이 가장 높게 예측하며 혼합분율 연소모델은 실험보다는 낮게 예측하였다. EDC 3-step Mixed 모델이 가장 예측성능이 좋았지만 EDC 2-step Mixing Controlled 모델도 충분히 합리적인 수준으로 예측하고 있음을 확인하였다. EDC 1-step Mixing Controlled 모델에 기존에 제안된 CO 수율을 적용할 경우 CO 농도에 대해서 너무 과소 예측하며 CO 예측 정확도를 높이기 위해 수율을 높이면 $CO_2$ 농도에 대한 합리적인 예측이 어려워지는 문제점이 있었다.

• 전기학회논문지P
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• 제54권3호
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• pp.141-147
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• 2005

In this paper, We are going to propose the fire protection system with using CAN(Controller Area Network). The larger, higher and deeper buildings are, the more dangerous people are when fire happens. We should be aware of the problems of prior fire protection system. Therefore, we construct embedded system based on CAN communication that is capable of N:N communication, and build independent fire protection system. If the fire is occurred on the building, the problem is that how fast we can detect the fire and put off it by using available system. this is major factor that reduces damage of our wealth. therefore in this studies We would like to design more stable system than current system. this system that is based on CAN communication which is available N:N communication constructs and is designed to compensate for each fault so that our aim is to reduce the line of system and cost of installation and to suppose future type fire protection system. We are simulated by NIST FDS(Fire Dynamics Simulator) to prove the efficiency of this system.

• 국제초고층학회논문집
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• 제10권4호
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• pp.345-364
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• 2021

Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S / V_BO), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.

• 한국산학기술학회논문지
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• 제18권5호
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• pp.716-722
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• 2017

본 연구에서는 Fire Dynamics Simulation (FDS)를 이용하여 화재 기류 전파 경로 상에 플랜트 설비 유무가 공간 내 열유동 특성에 미치는 영향을 알아보기 위해 화원 위치에 따른 지하 복합 발전 플랜트 내 화재 해석을 수행하였다. 화원의 크기는 10 MW이며, 화원 상부의 장애물(설비)의 유무에 따라 화원 위치가 천장 및 화원 상부에서의 열 기류 선단의 전파 특성을 미치는 영향을 정량적으로 비교분석하였다. 결과로서, 화원 상부에 장애물이 있을 경우, 화재 기류가 화원 상부 천장에 도달하는 시간이 장애물이 없을 때에 비해 약 5 배가량 증가하였다. 화원 상부 천장 벽면의 천장 기류 시작 지점으로부터 거리에 따른 각 지점에서 열 기류 선단의 전파 시간의 평균적으로 장애물이 없는 경우에 비해 약 70% 가량 증가하였으며, 특히 10 m 지점에서는 4 배 가까이 증가하였다. 이는 장애물이 화원으로부터 발생하는 수직 열기류의 흐름을 방해하고, 장애물 뒤 쪽에 불안정한 후류가 형성되었기 때문이다. 따라서 지하복합 발전 플랜트 내 피난 및 재난 관리의 초기 대응 목적의 화재 감지 설비 시스템 설계 시 화재 시나리오에 따른 열유동 분석이 중요할 것으로 판단된다.

• 한국분무공학회지
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• 제13권3호
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• pp.156-161
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• 2008

The present article reports a numerical study on the fire characteristic change by water-mist in under-ventilated compartments. The natural gas and heptane pool fires are used as fire sources, which are located in the bottom center of the 2/5 reduced-scaled model of the ISO 9705 standard room. The fire modeling using the FDS (Fire Dynamics Simulator) is validated by comparison with previously published experimental results. For temperature and combustion gas concentrations at two positions located in the upper layer of compartment, the predicted results with and without water-mist are compared each other. The results show that under the water-mist operation, the predicted temperature and carbon monoxide concentration reduce as $300{\sim}400^{\circ}C$ and about 20%, respectively, compared to those without water-mist.