• Fire Protection Technology
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• s.37
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• pp.36-37
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• 2004

• Fire Protection Technology
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• s.42
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• pp.34-40
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• 2007

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.31-37
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• 2014

The aim of this work is to provide new experimental data on the pyrolysis characteristics and the minimum ignition energy (MIE) by using the same high-density polyethylene (HDPE) powder in domestic HDPE dust explosion accident. To evaluate the explosion sensitivity of HDPE, thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC) and MIE apparatus (MIKE-3, K$\ddot{u}$hner) was conducted. The measurements showed the volume median diameter of $61.6{\mu}m$ but the particle number density of 98 % in the range $0.4{\sim}4{\mu}m$. The ignition temperature from the results of TGA and DSC in HDPE dust layers was observed in the range of $380{\sim}490^{\circ}C$. MIE was measured under 1 mJ in the HDPE dust concentration of $1200{\sim}1800g/m^3$, it was found that the ratio of particle number density in the range $0.4{\sim}4{\mu}m$ was very high (98%).

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.566-573
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• 1994

The diamond synthesis by combustion flame method is considerably affected by the substrate surface temperature and its distribution which are mainly controlled by the ratio of mixed gas, $O_2/C_2H_2$. In order to elucidate the role of gas ratio in the diamond synthetic process by combustion flame, under various gas ratios (R=0.87~0.98; R=ratio of flow-rate of $O_2/C_2H_2$ gas) the substrate temperature was measured by using thermal video system and the morphological change of diamond crystals was analysed by using SEM, Raman spectroscope, and X-ray diffraction method. With increasing the gas ratio, i.e., decreasing the hydrocarbon content, the nucleation rate of diamond crystal was lowerd. It was also found that the morphology of diamond crystals changed from the cubo-octahedron type consisting of (100), (111) plane to the octahedron type of (111) plane. The increase of the substrate temperature consistently resulted in the increase of the nucleation rate as well as the growth rate of diamond crystals in which the surface of diamond crystal dominantly consisting of (100) plane.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2376-2384
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• 1992

A theoretical analysis is carried out to predict the characteristics of transient ignition phenomena for the spherical fuel droplets cloud with non-uniform droplet size and number density distribution. Numerical calculations are performed for various cases depending on the combinations of the major parameters such as ambient temperature and initial distributions of droplet size and number density. The results of present study show that the ignition delay decreases for higher ambient temperature and smaller droplet size. Droplets cloud of hollow type with outer concentrated distribution ignites most rapidly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.4
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• pp.33-38
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• 1982

A successful operation of underground oil storage cavern depends on water-tightness around cavern by groundwater. If water-tightness is not secured, gas bubbles would leak out and oil would migrate to an adjacent empty cavern. In this research an electrical analogy method was employed to study the influence of shape of cavern on gas leakage and the required natural groundwater level, relative oil level in two neighboring caverns and cavern spacing to prevent oil migration. The results show that gas leakage is prevented from a cavern with a ceiling of large curvature. The required values of factors to curtail the migration of oil are given on a graph.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.33-38
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• 2004

This study was performed to know watertightness and reduction effect and crack occurred by hydration heat, restraint of multiplication of hydration heat, through mechanical test, strength test and crack control test using fluosilicate salt based inorganic compound made from by-product during phosphoric acid manufacturing process. Mix proportions for experiment were modulated at 0.45 of water to cement ratio and $0.5-2.0\%$ of adding ratio of fluosilicate salt based inorganic compound. Evaluation for watertightness of concrete was carried out permeability, absorption test and porosity analysis. Effect of crack reduction was evaluated by length, drying shrinkage as well as stress change of hardened concrete at unrestraint/restraint state and also elucidated crack pattern on the concrete surface. It is ascertained that characteristics of crack resistance and watertightness for concrete was improved by an adequate addition of fluosilicate salt based inorganic compound.

• Journal of the Korea Institute of Building Construction
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• v.11 no.1
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• pp.51-59
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• 2011

With the increased demand for membrane structures in recent years, there have been many studies of their mechanical properties, to the extent that such structures have become recognized as independent structures with a level of safety and durability comparable to those of other general structures. But in reality, the study for the maintenance of membrane structures has not been as active. In particularly, the study of watertightness from the perspective of maintenance has been very limited. Accordingly, a study on securing watertightness performance and the guidelines for maintenance is necessary. In this study, through a case study of water leakage accidents in membrane structures overseas, causes of leakage were selected from the membrane material itself, joint parts and open door of roof part in membrane structure. The water leakage and deterioration elements were analyzed from those leakage causes. The degree of importance of the water leakage and deterioration index was also designated using the AHP (Analytic Hierarchy Process) method. As a result, the basic technical index was suggested for the maintenance of the roofs of large-span membrane structures to prevent water leakage. This index will be used to make a guideline for the long-term maintenance of the roofs of large-span membrane structures.

• 건축구조
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• v.9 no.3
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• pp.44-46
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• 2002

• NEWSLETTER 전기공업
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• no.94-6 s.103
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• pp.34-38
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• 1994