• Title/Summary/Keyword: Fire Site Risk

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Detection of Toluene Hazardous and Noxious Substances (HNS) Based on Hyperspectral Remote Sensing (초분광 원격탐사 기반 위험·유해물질 톨루엔 탐지)

  • Park, Jae-Jin;Park, Kyung-Ae;Foucher, Pierre-Yves;Kim, Tae-Sung;Lee, Moonjin
    • Journal of the Korean earth science society
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    • v.42 no.6
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    • pp.623-631
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    • 2021
  • The increased transport of marine hazardous and noxious substances (HNS) has resulted in frequent HNS spill accidents domestically and internationally. There are about 6,000 species of HNS internationally, and most of them have toxic properties. When an accidental HNS spill occurs, it can destroys the marine ecosystem and can damage life and property due to explosion and fire. Constructing a spectral library of HNS according to wavelength and developing a detection algorithm would help prepare for accidents. In this study, a ground HNS spill experiment was conducted in France. The toluene spectrum was determined through hyperspectral sensor measurements. HNS present in the hyperspectral images were detected by applying the spectral mixture algorithm. Preprocessing principal component analysis (PCA) removed noise and performed dimensional compression. The endmember spectra of toluene and seawater were extracted through the N-FINDR technique. By calculating the abundance fraction of toluene and seawater based on the spectrum, the detection accuracy of HNS in all pixels was presented as a probability. The probability was compared with radiance images at a wavelength of 418.15 nm to select abundance fractions with maximum detection accuracy. The accuracy exceeded 99% at a ratio of approximately 42%. Response to marine spills of HNS are presently impeded by the restricted access to the site because of high risk of exposure to toxic compounds. The present experimental and detection results could help estimate the area of contamination with HNS based on hyperspectral remote sensing.

Determination of Thermoluminescence Properties of MgB4O7 Doped with Dy3+, La3+ and Ho3+ for a Light Tracer Application (비화공식 예광탄 응용을 위한 Dy3+, La3+ 그리고 Ho3+이 도핑된 MgB4O7의 열 발광 특성 분석)

  • Park, Jinu;Kim, Nakyung;Choi, Jiwoon;Koh, Jaehyuk;Chin, Hee Sik;Jung, Duck Hyeong;Shin, Byungha
    • Korean Journal of Materials Research
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    • v.32 no.1
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    • pp.9-13
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    • 2022
  • Bullets flying with a light from the back are called "tracers". Tracers are ignited by the combustion gas of the propellant and emit bright light that allows the shooter to visually trace the flight path. Therefore, tracers mark the firing point for allies to assist shooters to hit target quickly and accurately. Conventional tracers are constructed with a mixture of an oxidizing agent, raw metal, and organic fuel. Upon ignition, the inside of the gun can be easily contaminated by the by-products, which can lead to firearm failure during long-term shooting. Moreover, there is a fire risk such as forest fires due to residual flames at impact site. Therefore, it is necessary to develop non-combustion type luminous material; however, this material must still use the heat generated from the propellant, so-called "thermoluminescence (TL)". This study aims to compare the TL emission of Dy3+, La3+ and Ho3+ doped MgB4O7 phosphors prepared by solid state reaction. The crystal structures of samples were determined by X-ray diffraction and matched with the standard pattern of MgB4O7. Luminescence of various doses (200 ~ 15,000 Gy) of gamma irradiated Dy3+, La3+ and Ho3+ (at different concentrations of 5, 10, 15 and 20 %) doped MgB4O7 were recorded using a luminance/color meter. The intensity of TL yellowish (CIE x = 0.401 ~ 0.486, y = 0.410 ~ 0.488) emission became stronger as the temperature increased and the total gamma-ray dose increased.

High Thermoluminescence Properties of Dy+Ce, and Dy+Na Co-Doped MgB4O7 for a Light Tracer Application (비화공식 예광탄 응용을 위한 Dy+Ce 및 Dy+Na 이중 도핑된 MgB4O7의 높은 열발광 특성)

  • Jinu Park;Nakyung Kim;Jiwoon Choi;Youngseung Choi;Sanghyuk Ryu;Sung-Jin Yang;Duck Hyeong Jung;Byungha Shin
    • Korean Journal of Materials Research
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    • v.33 no.1
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    • pp.15-20
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    • 2023
  • 'Tracers' are bullets that emit light at the backside so that the shooter can see the trajectory of their flight. These light-emitting bullets allow snipers to hit targets faster and more accurately. Conventional tracers are all combustion type which use the heat generated upon ignition. However, the conventional tracer has a fire risk at the impact site due to the residual flame and has a by-product that can contaminate the inside of the gun and lead to firearm failure. To resolve these problems, it is necessary to develop non-combustion-type tracers that can convert heat to luminance, so-called 'thermoluminescence (TL)'. Here, we highly improve the thermoluminescence properties of MgB4O7 through co-doping of Dy3++Ce3+ and Dy3++Na+. The presence of doping materials (Dy3+, Ce3+, Na+) was confirmed by XPS (X-ray photoelectron spectroscopy). The as-synthesized co-doped MgB4O7 was irradiated with a specific radiation dose and heated to 500 ℃under dark conditions. Different thermoluminescence characteristics were exhibited depending on the type or amounts of doping elements, and the highest luminance of 370 cd/m2 was obtained when Dy 10 % and Na 5 % were co-doped.