• Title/Summary/Keyword: smoldering

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The Development of UV-IR Combination Flame Detector (UV-IR 복합형 화재감지장치 개발)

  • 이복영;권오승;정창기;박상태
    • Journal of the Korean Society of Safety
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    • v.16 no.1
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    • pp.1-8
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    • 2001
  • All objects emit thermal radiation and this radiation is the basis of the techniques used to detect flames. The usual phenomena occurring in the initial stage of the fire are generally invisible products of a combustion and visible smoke. Liquid or gaseous materials do not undergo a smoldering stage so that fires develop very rapidly. Also, the heat generated by the initial flames is usually not sufficient to activate a heat detector. In this case the most effective criterion for automatic fire detection is the flame. According to the fire regulation of korea, the compulsory standard provided that a flame detector shall be installed in a place that the attachment height of detector is higher than 20 m, chemical plants, hangar, refinery, etc.. The results of the research and development are discriminated between a flame and other radiant emitters, developed a UV detector tube contains an inert gas which absorbs UV radiation, developed PZT pyroelectric element is based on the use of photovoltanic cell, developed IR band-pass filter that only allow a 4.3 $\mu\textrm{m}$ radiation wavelength to reach the sensors and developed UV-IR combination flame detector combined into a single detection device.

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Smoke Density and Operation of Fire Detector Influenced by Air Stream (기류순환이 연기농도와 감지기 작동에 미치는 영향)

  • 이복영;이병곤
    • Fire Science and Engineering
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    • v.16 no.4
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    • pp.28-32
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    • 2002
  • The performance based design in fire detection system, the effect of high airflow and dilution of smoke produced in any fire situation serve to increase the response time of point-type smoke detectors. This study investigated the smoke density of ceiling, under the air stream and in normal status when fire type is smoldering fires. The result of study, smoke generated in the fire was swept away from nearby spot type smoke detector which failed to actuate because dispersed in diluted form around the room. The concept of performance based design in fire detection system of protected area influenced by high airflow provided the need of active fire detection system such as air sampling smoke detection system.

EFFECT OF CIGARETTE PAPER ON CIGARETTEAPPEARANCE BURN RATE AND SIDESTREAM SMOKE

  • Jr Vladimir Hampl
    • Proceedings of the Korean Society of Tobacco Science Conference
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    • 2000.05a
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    • pp.12-21
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    • 2000
  • The smoke from a burning cigarette is classified as mainstream, which is the smoke inhaled by the smoker during a puff, and sidestream, which is defined by ISO 10185 as all smoke which leaves a cigarette during the smoking process other than from the butt end. Most of the sidestream smoke is generated during static burn, that is, in between puffs. The amount of sidestream smoke generated by a cigarette depends on the cigarette construction, tobacco blend, and properties of the cigarette paper, The main paper properties affecting sidestream smoke generation are: porosity, basis weight, type and amount of filler, type and amount of burn additive.Sidestream smoke is composed of a visible phase (small liquid droplets) and an invisible phase (gaseous molecules). This paper focuses on the visible portion of the sidestream smoke. Optical methods, which are based on the relationship between light scattering and density of the rising plume of smoke, have been used successfully by the industry. However, the present trend is to use gravimetric methods where the particulate matter is captured on a Cambridge(R) filter pad and weighed. The gaseous portion of the sidestream smoke, which does not contribute to the visible sidestream smoke, passes through the Cambridge filter pad.Sidestream smoke reduction is achieved by modifying certain mass transport processes occurring in a smoldering cigarette. There are four main pathways for reducing sidestream smoke: A) less tobacco burned, B) slower rate of tobacco combustion, C) more efficient trapping of smoke by the cigarette paper, and D) more complete combustion of tobacco. This paper discusses how the physical properties of paper and cigarette construction affect sidestream smoke reduction via the above four mechanisms.

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A Fire Detection System Using Fuzzy Logic with Input Variables of Temperature and Smoke Density (열과 연기농도를 입력변수로 갖는 퍼지로직을 이용한 화재감지시스템)

  • Hong Sung-Ho;Kim Doo-Hyun;Kim Sang-Chul
    • Fire Science and Engineering
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    • v.18 no.4
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    • pp.42-51
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    • 2004
  • This paper presents a study on the analysis of fire detection system using fuzzy logic with input variables of temperature and smoke density. The input variables for the fuzzy logic algorithm are measured by fire experiment of small scale with temperature detector and smoke detector. The antecedent part of fuzzy rules consists of temperature and smoke density, and the consequent part consists of fire possibility. Also the triangular fuzzy membership function is chosen for input variables and fuzzy rules to simplify computation. In order to calculate fuzzy values of such fuzzy system, a computer program is developed with Matlab based on graphics user interface. The experiment was conducted with paper and ethanol to simulate flaming fire and with plastic and sawdust to model smoldering fire. The results showed that the fire detection system presented here was able to diagnose fire very precisely. With the help of algorithms using fuzzy logic we could distinguish whether fire or not.

The Study to ETS Exposure and Their Biomarkers in Hair of Restaurant Workers (식당 종업원의 환경 담배 연기(ETS)의 노출과 머리카락 중 생체지표 연구)

  • Jo Seong-Joon
    • Environmental Analysis Health and Toxicology
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    • v.19 no.2
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    • pp.169-176
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    • 2004
  • ETS (environmental tobacco smoke) is composed of exhaled mainstream smoke (MS) from the smoker, sidestream smoke (SS) emitted from the smoldering tobacco between puffs and contaminants that diffuse through the cigarette paper and mouth between puffs. These emissions contain both vapor phase and particulate contaminants. ETS is a complex mix of over 4,000 compounds. This mix contains many known or suspected human carcinogens and other toxic agents. More of these toxic compounds are found in SS than in MS. Workplace exposure to ETS can result in significant smoke intake, and passive smoke exposure may be related to impair respiratory function and an increase risk of lung cancer in nonsmokers. For nonsmokers sharing a work environment with cigarette smokers, the workplace must be considered hazardous independently of any specific industrial toxic exposure. The risk is particularly important when a high percentage of the workers smoke or where smokers and nonsmokers work in poorly ventilated areas. Nicotine is converted in the body to cotinine; cotinine therefore can be used as an indirect measure of a person's recent exposure to tobacco smoke. Levels of nicotine in hair and levels of cotinine in body fluids (saliva and urine) have been shown to increase with increasing environmental nicotine levels and with self-reported ETS exposure. The measurement of nicotine or cotinine in hair may be more appropriate for longer-term exposure to tobacco. The purpose of this study is to comparing airborne nicotine levels and hair cotinine level in restaurant workers. Concentration of airborne nicotine and hair nicotine (and cotinine) is closely related to exposed frequency of sidestream smoke in the workplace. Nicotine in hair is a better predictor of airborne nicotine than hair cotinine. Hair nicotine can be a useful tool to assess ETS exposure interventions. It may have limiting levels of ETS exposure by placing regulatory restrictions on smoking in workplaces and in public spaces.

Plasma Soluble CD30 as a Possible Marker of Adult T-cell Leukemia in HTLV-1 Carriers: a Nested Case-Control Study

  • Takemoto, Shigeki;Iwanaga, Masako;Sagara, Yasuko;Watanabe, Toshiki
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.18
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    • pp.8253-8258
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    • 2016
  • Elevated levels of soluble CD30 (sCD30) are linked with various T-cell neoplasms. However, the relationship between sCD30 levels and the development of adult T-cell leukemia (ATL) in human T-cell leukemia virus type 1 (HTLV-1) carriers remains to be clarified. We here investigated whether plasma sCD30 is associated with risk of ATL in a nested case-control study within a cohort of HTLV-1 carriers. We compared sCD30 levels between 11 cases (i.e., HTLV-1 carriers who later progressed to ATL) and 22 age-, sex- and institution-matched control HTLV-1 carriers (i.e., those with no progression). The sCD30 concentration at baseline was significantly higher in cases than in controls (median 65.8, range 27.2-134.5 U/mL vs. median 22.2, range 8.4-63.1 U/mL, P=0.001). In the univariate logistic regression analysis, a higher sCD30 (${\geq}30.2U/mL$) was significantly associated with ATL development (odds ratio 7.88 and the 95% confidence intervals 1.35-45.8, P = 0.02). Among cases, sCD30 concentration tended to increase at the time of diagnosis of aggressive-type ATL, but the concentration was stable in those developing the smoldering-type. This suggests that sCD30 may serve as a predictive marker for the onset of aggressive-type ATL in HTLV-1 carriers.

Fire Patterns According to the Blood Hb-CO Concentration of Charred Bodies (소사체의 혈중 헤모글로빈-일산화탄소 농도에 따른 연소형태 연구)

  • Choi, Seung-Bok;Oh, Bu-Yeol;Choi, Don-Mook
    • Fire Science and Engineering
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    • v.26 no.3
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    • pp.40-48
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    • 2012
  • Fire patterns have been used to determine the origin and cause of fires in every setting imaginable. However, it is very difficult to identify fire patterns and causes from the fire-damaged remains of a devastated structure. If someone was killed by the fire, it is possible to identify fire patterns by analyzing the Hb-CO concentration in charred bodies of deceased as well as the pace of the fire. For example, a low level of Hb-CO concentration in the charred bodies indicate a rapid fire with accelerants and the death was caused by severe heat and thick toxic fumes. However, a high level of Hb-CO concentration in the charred bodies demonstrates that the fire was slow and/or there was a flameless form of combustion. Thus, it is possible to identify fire patterns through analyzing the level of Hb-CO concentration on the dead from the fire. In this study, the Hb-CO concentration in the charred bodies was from 3 % at the case of gas burning oneself to death to 93 % at the death caused by smoldering fire.

A Study on the Adaptability of the CO Sensor as A Fire Detection Sensor According to the Test Fire Source of UL 268 (UL 268 시험화원에 따른 CO센서의 화재감지센서로서의 적용성에 관한 연구)

  • Lee, Chun-Ha;Sung, Want-Ki;Lee, Jong-Hwa;Kim, Hyeong-Gweon;Jee, Seung-Wook;Kim, Si-Kuk
    • Fire Science and Engineering
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    • v.28 no.2
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    • pp.54-63
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    • 2014
  • The purpose of this study is to test the adaptability of the CO sensor as a fire detector by analyzing its sensing characteristics on fire. In order to test the applicability, we designed and made a fire testing ground whose size is similar to that regulated by UL 268, carried out real fire tests suggested by UL 268, and conducted a comparison analysis on the sensing characteristics between the CO sensor and a photoelectric smoke detector by different types of fire source. The experiment result to the sensing characteristics of the CO sensor is about twice to three times faster than that of the photoelectric smoke detector, proceeding with incomplete combustion such as paper and wood fire source in the initial fire. Especially in case of wood smoldering fire, sensing characteristics of the CO sensor is very excellent.

Effects of Char Produced from Burning Wood Combustibles on Thermal Pyrolysis (목재 가연물의 연소 시 생성되는 탄화가 열분해에 미치는 영향)

  • Hong, Ter-Ki;Ryu, Myung-Ho;Lee, Jong Won;Park, Seul-Hyun
    • Fire Science and Engineering
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    • v.33 no.5
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    • pp.7-12
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    • 2019
  • To investigate the influence of the char layer formed during the combustion process on the pyrolysis of wood combustibles, ISO 5660-1 cone calorimetry experiments and Fire dynamics simulator (FDS) simulations were performed, and the results from these two methods were compared. The wood combustible selected as the fuel for this study, Douglas fir, has been widely used for the production of building materials, furniture, etc. The heat release rate (HRR) measured from the cone calorimetry experiment was in good agreement with the result predicted by the FDS simulation. However, the FDS simulation failed to predict the heat released by the smoldering combustion process, due to the absence of the char surface reaction in the model. The FDS simulation results clearly indicate that the char layer formed on the surface of combustibles produces a thermal barrier which prevents heat transfer to the interior, thickening the thermal depth and thus reducing the pyrolysis rate of combustibles.

Experimental Study of the Blowoff Flame Phenomena Due to Changes of Balcony Length (발코니 길이변화에 의한 화염분출성상의 실험적 고찰)

  • Kim, Hoe-Cheon;Sohn, Jang-Yeul;Park, Hyung-Ju
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.3
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    • pp.235-244
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    • 2007
  • In the case of the fire outburst within a partitioned space, it can disappear inside it through smoldering process if the fire cannot obtain sufficient imflammability. On the contrary, if it obtains it, the fire is not restricted within the room, spreading to the higher levels beyond outside windows and the compartment room. The method to prevent the fire spread through windows is considered to build a balcony or equip with sprinkler facilities. This case study is to identify which effects and controlibility a balcony brings about on the spread of fire through a full scale model experiment. In order to understand the effects of fire spread on the upper levels of the room on fire by changing the length of balcony, the temperature was measured, radiant heat was investigated, and products of combustion were analyzed. The result showed that when fire occured, longer length of the balcony, which linked to the outside wall of the apartments, led to the blocking of the fire spread, lower level of radiant heat, and significantly less transfer of toxic gases, and the driving force of the outburst of flame was identified as the attractive force due to the turbulence of uncombusted gases, which exist on the upper level of the outbursting flame.