• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.144-152
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• 2023

To evaluate the fire risk of combustible materials, Chung's equations VII, VIII, and IX were newly established. The fire risk index-IX (FRI-IX) and fire risk rating (FRR) were calculated. Ginkgo, dawn redwood, toona, lime, walnut, and polymethylmethacrylate (PMMA) were selected as test specimens. The combustion characteristics were evaluated using a cone calorimeter according to ISO 5660-1. After combustion, the fire performance index-VII (FPI-VII) of the specimens, varied between 15.15 and 182.53 s²/kW, as determined by Chung's equations, and the fire growth index-VII (FGI-VII) varied between 0.0023 and 0.0165 kW/s². The fire performance index-VIII (FPI-VIII) based on PMMA varied between 0.29 and 3.45, and the fire growth index-VIII (FGI-VIII) varied between 2.88 and 20.63. The FRI-IX, which is the fire risk rating, showed dawn redwood has a very high fire risk, with FRI-IX values of 71.14 (fire risk rating: G). Therefore, wood with a large amount of volatile organic compounds and a low bulk density showed a high value of FRI-IX by lowering FPI-VII and FPI-VIII and increasing FGI-VII and FGI-VIII.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.29-36
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• 2024

The fire risk and fire safety of four types of wood were comprehensively evaluated according to Chung's equation-XII. White ash, willow, fraxinus mandshurica, and sagent cherry trees were selected as test specimens. A cone calorimetery (ISO 5660-1) was used to examine the combustion characteristics of the test piece, and finally, the fire risk rating (FRR) was predicted using the fire risk index-XII (FRI-XII). The predicted fire performance index-X (FPI-X) and fire growth index-X (FGI-X) ranged from 469.03 to 1109.73 s²/kW and 0.0009 to 0.0280 kW/s², respectively. Additionally, the fire performance index-XI (FPI-XI) and fire growth index-XI (FGI-XI) ranged from 0.41 to 0.97 and 1.11 to 3.11, respectively. The fire risk index-XII (FRI-XII), representing a fire risk rating, showed that the fire risk of frasxinus mandsurica tree (FM) was very high at 7.60 (fire risk rating: D). And it was compared with Chung's equation-IX, fire risk index-IX (FRI-IX). The fire risk ratings according to FRI-IX and FRI-XII were generally high for willow and frasxinus mandsurica trees. Additionally, the results of FRI-XII and FRI-IX had a similar relationship, and the size of each fire safety rating closely matched each other.

• Geotechnical Engineering
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• v.10 no.2
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• pp.85-96
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• 1994

Resonant column test huts been widely used as a primary laboratory testing technique in investigating dynamic soil properties expressed in therms of shear and Young's moduli and material damping. In thin Paper, dynamic Properties of typical Korean subgrade boils are investigated at shearing strains between 10-4% and 10-1% using Stokoe-type resonant column teat. The elastic threshold strains(yte) above which shear modulus and damping ratio are affected by strain amplitude, are defined at strain amplitude of about 10-3%. Below yte", small-strain shear modulus (Gmn) increases with confining pressure (Qc) as proportional to (Qe)0.61, and small-strain damping ratio(Dmin) ranges between 1% and 5.7%. Above yte, normalized shear modulus reduction curve(G/Gma. versus log strain) can be quite well expressed with Ramberg Osgood stress -strain equation and match well the curve suggested for sand by Seed and Idriss.riss.