• Journal of the Korean Society of Safety
• /
• v.37 no.2
• /
• pp.69-75
• /
• 2022

Fire-alarm systems are safety equipment that facilitate rapid evacuation and early suppression in case of fire. It is highly desirable that fire-alarm systems have low false-alarm rates and are thus reliable. Until now, researchers have attempted to improve detector performance by applying new technologies such as IoT. To this end, IoT-based fire-detection systems have been developed. However, due to scarcity of large-scale operational data, researchers have barely studied malfunctioning in fire-alarm systems or attempted to reduce false-alarm rates in these systems. In this study, we analyzed false-alarm rates of smoke/temperature detectors and unwanted fire-alarm signal patterns at K institution, where Korea's largest IoT-based fire-detection system operates. After analyzing the fire alarm occurrences at the institution for five years, we inferred that the IoT-based fire-detection system showed lower false-alarm rates compared to the automatic fire-detection equipment. We analyzed the detection pattern by dividing it into two parts: normal operation and unwanted fire alarms. When a specific signal pattern was filtered out, the false-alarm rate was reduced to 66.9% in the smoke detector and to 46.9% in the temperature detector.

• Fire Science and Engineering
• /
• v.2 no.3
• /
• pp.3-9
• /
• 1988

This paper is study about establishment with water membrane sprinkler in fire prevention block of special Building. The testing program was directed toward investigating the temperature of fire and adjacent room. The results of fire test indicated that under the test conditions in this study, adjacent room temperature is very low in compare with fire room temperature at operating of water membrane sprinkler. Therefore, if exclusion of smoking can be soluted, substitution of water membrance sprinkler in fire resistance wall of fire prevention block is possible.

• Architectural research
• /
• v.10 no.1
• /
• pp.1-11
• /
• 2008

A Steel column with damaged spray-applied fire resistive material (SFRM) may exhibit reduced structural performance due to the effects of elevated temperature during fire events. Thus, the fire load behavior of steel columns with removed or reduced SFRM needs to be examined to predict the structural damage by fire. FEM analyses were performed for the flange thinning removal models in which the SFRM was reduced as a constant strip in thickness at the top flange of the column. The temperature results for all models obtained from the heat transfer analyses were included as an initial condition in the FEM structural analyses. In this study, the results of analysis show that even small remnants of SFRM led to an effective reduction of temperature at any given fire duration, and improved significantly the axial load capacity of a column as compared to the complete removal cases of SFRM.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.05a
• /
• pp.212-213
• /
• 2014

In case of fire spray protection sheath, fire resisting capacity is assessed for each material and installation method according to fire-resistive construction recognition. This study reviews effects of the percentage of water content that exist in fire spray protection sheath during the assess process of fire resisting capacity on fire resisting capacity, and changes of the percentage of water content according to temperature conditions. As a result of exams, as curing temperature is higher and thickness of specimen is thinner, decrease of the percentage of water content becomes significant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.1
• /
• pp.41-48
• /
• 2009

The present study has been performed to investigate the thermal characteristics of under-ventilated compartment fire which is a typical fire condition in structures. A series of fire experiments was conducted to characterize the thermally driven flow in a 2/5 scale ISO 9705 fire compartment. Three different fuels were used in this test series, methane gas, heptane pool, and polystyrene pellets fire. In order to measure accurate temperature, double shield aspirated thermocouples reducing the effect of radiative energy exchange on temperature measurement were used in addition to bare bead thermocouples. The upper layer temperature for well ventilated fire was increased with increasing heat release rate, but it was slightly decreased for under-ventilated fire. The measured temperatures in the upper layer at the front sampling location were higher than at the rear. Thermal characteristics through the doorway were also analysed for a wide range of heat release rates. This study provides a comprehensive and quantitative assessment of fire behavior for under-ventilation condition of fire.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.8 no.4
• /
• pp.250-259
• /
• 2006

This study looks into forest fire occurrence hazards according to the change of temperature and humidity over thirty years at interval of ten days. We used data from the forest fire inventory from 1995 to 2004 and weather data such as average temperature and relative humidity for 30 years from 1971 to 2000. These data were expressed as a database with ten-day intervals for 76 weather stations. Forest fire hazards occurred in the spring season from the end of March to the middle of April. For the first step, the primitive surface of temperature and humidity was interpolated by IDW (the standard interpolation method). These thematic maps have a 1 km by 1 km grid spacing resolution. Next, we executed a simple regression analysis after extracting forest fire frequency, temperature and humidity values from 76 weather stations. The results produced a coefficient of determination ($R^2$) ranging from 0.4 to 0.6. Moreover, the estimation of forest fire occurrence hazards during early April was very high at Gyeongbuk Interior, Chungcheong Interior and part of Gangwon. The range of temperature and humidity having an influence on forest fire occurrence was as follows: average temperature and relative humidity in early April was $9-12^{\circ}C$ and 61-65%. At the end of March, temperature was $6-10^{\circ}C$, humidity 62-67%, and temperature was $11-14^{\circ}C$ and humidity 60-67% in the middle of April.

• Steel and Composite Structures
• /
• v.15 no.6
• /
• pp.705-724
• /
• 2013

The behaviour of steel column at elevated temperature is significantly different than that at ambient temperature due to its changes in the mechanical properties with temperature. Reported literature suggests that steel column may become vulnerable when exposed to fire condition, since its strength and capacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistance of non-insulated steel columns under fire exposure through finite element analysis. The studied parameters include moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns at different axial load levels. It was observed that when the temperature of the column was increased, there was a significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover, it was noted that the stiffness and ductility of steel columns decreased sharply with the increase in temperature, especially for temperatures above $400^{\circ}C$. In addition, the lateral load capacity and the moment capacity of columns were plotted against fire exposure time, which revealed that in fire conditions, the non-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes of fire exposure.

• Journal of the Korean Society of Safety
• /
• v.39 no.3
• /
• pp.7-13
• /
• 2024

This study examines the physical characteristics of self-regulating heating cables caused by increased temperature and fire risk due to local degradation. A thermo hygrostat system, a convection dryer, a digital multimeter (Agilent 34465 A), NI DAQ, and the LabVIEW program were used to assess the physical properties in response to temperature fluctuations. As the temperature increases, the resistance of the self-regulating heating cable increases; however, when the critical point is exceeded, the resistance sharply decreases. A problem arises when the resistance value cannot return to its original state even though the temperature is lowered to the initial state. Moreover, when the ambient temperature rises while power is applied, the resistance value initially increases, and the flowing current decreases, maintaining a constant state. However, when the critical temperature is exceeded, the flowing current increases because of a rapid decrease in the resistance value, progressing to ignition. When the resistance value decreases because of the deterioration of one local area, the total resistance value becomes less than the initial resistance value. Therefore, the flowing current increases and an ignition problem occurs at one location where deterioration occurs. Despite the sustained flames and arcs resulting from the changes in the overall physical properties of the self-regulating heating cable and resistance variations due to local decline, the fire continued as the flowing current was lower than the operating current of the circuit breaker, failing to cut the power. In the case of self-regulating heating cables and heating wires, which are the leading causes of fires in winter, efforts are needed to ensure the need for periodic maintenance and the use of KS-certified products.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1275-1281
• /
• 2011

This paper presents synthetic circumstantial judgement system that detects and predicts a fire in subway station. Unlike conventional fire surveillance systems that judge the fire or not through smoke, CO, temperature or variation of temperature, a proposed system discovers a fire more easily or gives the alarm high possibility of fire to operator through recognition of fire levels based on Fuzzy Inference System using by FCM and information of objects from video data.

• Fire Science and Engineering
• /
• v.22 no.4
• /
• pp.85-94
• /
• 2008

The purpose of this study is to obtain the fundamental fire resistance performance of engineered cementitious composites (ECC) under fire temperature in order to use the fire protection material in high-strength concrete structures. The present study conducted the experiment to simulate fire temperature by employing of ECC and investigated experimentally the explosion and cracks in heated surface of these ECC. In the experimental studies, 5 HSC specimens are being exposed to fire, in order to exami ne the influence of vari ous parameters (such as depth of layer=20, 30, 40 mm; construction method=lining and repairing type) on the fire performance of HSC structures. Employed temperature curve were ISO 834 criterion (3 hr), which are severe in various criterion of fire temperature in building structures. The numerical regressive analysis and proposed equation to calculate ambient temperature distribution is carried out and verified against the experimental data. By the use of proposed equation, the HSC members subjected to fire loads were designed and discussed.