• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.1988-1993
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• 2023

This experimental study investigated the effect of silica fume mixed in concrete blocks on laser-induced explosion behavior. We used a 5.3 kW fiber laser as a thermal source to induce explosive spalling on a concrete surface blended with and without silica fume. An analytical approach based on the difference in the removal rate and thermal behavior was used to determine the effect of silica fume on laser-induced explosive spalling. A scanner was employed to calculate the laser-scabbled volume of the concrete surface to derive the removal rate. The removal rate of the concrete mixed with silica fume was higher than that of without silica fume. Thermal images acquired during scabbling were used to qualitatively analyze the thermal response of laser-induced explosive spalling on the concrete surface. At the early stage of laser heating, an uneven spatial distribution of surface temperature appeared on the concrete blended with silica fume because of frequent explosive spalling within a small area. By contrast, the spalling frequency was relatively lower in laser-heated concrete without silica fume. Furthermore, we observed that a larger area was removed via a single explosive spalling event owing to its high porosity.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.437-443
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• 2024

The purpose of radiological Dispersal Device(RDD) is to kill people by explosives and to cause radiation exposure by dispersing radioactive materials. And It is a form of explosive that combines radioactive materials such as Co-60 and Ir-192 with improvised explosives. In this study, we tested and evaluated whether it was possible to read the internal structure of an explosive using X-rays in a radioactive explosive situation. The improvised explosive device was manufactured using 2 lb of model TNT explosives, one practice detonator, one 9V battery, and a timer switch in a leather briefcase measuring 41×35×10 cm³. The radioactive material used was the Co-60 source used in the low-level gamma ray irradiation device operated at the Advanced Radiation Research Institute of the Korea Atomic Energy Research Institute. The radiation dose used was gamma ray energy of 1.17 MeV and 1.33 MeV from a Co-60 source of 2208 Ci. The dose rates are divided into 0.5, 1, 2, and 4 Gy/h, and the exposure time was divided into 1, 3, 5, and 10 minutes. Co-60 source was mixed with the manufactured explosive and X-ray image reading was performed. As a result of the experiment, the X-ray image appeared black in all conditions divided by dose rate and time, and it was impossible to confirm the internal structure of the explosive. This is because γ-rays emitted from radioactive explosives have higher energy and stronger penetrating power than X-rays, so it is believed that imaging using X-rays is limited By blackening the film. The results of this study are expected to be used as basic data for research and development of X-ray imaging that can read the internal structure of explosives in radioactive explosive situations.

• The Journal of the Acoustical Society of Korea
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• v.9 no.3
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• pp.56-61
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• 1990

A New theoretical energy spectrum model for underwater explosive sound is introduced in order to calculate the precise spectral energy levels. This model is obtained by Fourier analysis of Gaussian formula which accurately represents the pressure wave generated from Underwater explosions. In case that explosive energy is very low. The spectrum levels which are obtained from the new theoretical model are in good agreement with the experimental spectrum levels, while the Weston model using impulse formula cannot interpret the experimental results.

• Explosives and Blasting
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• v.17 no.4
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• pp.18-31
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• 1999

The explosive forming has been used for many year to expand tubes into tubesheets. this process has demonstrated ability to direct carefully the energy of an explosive to expand tubes into tubesheet holes without damaging the tubesheet and without causing the excessive cold work at the tube I.D. that is normally associated with mechanical expansion. The success of explosive tube expansion provided the background for the development of the explosive tube plug. The main results are as follows : (1) The optimum explosives and explosive qualities are PETN, RDX, HMS and about 18~31gr/ft of explosive plugging in nuclear steam generator. (2) Explosive plugging's thickness is 0.9~1.8mm. If groove of 0.4 mm formed in plug outside, For the hydraulic leakage is go up, explosive plugging of formed groove are applicate tube and tubrplate. (3) Sheath is designed on the polyethylene of low density, In thermal impact test of the $430^\circ{C}$, hydraulic leakage is $300kg/cm^2$. (4) About 10~60mm oxide inclusions are existed on the space of explosive plug and tube protect to the leakage.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.938-945
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• 2004

Intrinsic safety is generally considered the safest method of operating electrical instrumention in potentially explosive atmospheres. The method of intrinsic safety limits the energy passing into the hazardus area. The energy limitation is provided by the use of safety barriers which are mounted in the safe area. Because of the energy limitation, regardless of the fault in the hazardous area, sufficient energy cannot be released to ignite the explosive atmosphere. The following industries are known to have hazardous locations: chemical. munitions, petrochemical, auto(paint spray booths), grain, waste water, printing, distillers, pharmaceutical. breweries, cosmetics, and utilities. In this paper, a isolator type barrier for ship(LNG, LPG, etc,) and test equipment confidence are proposed. The test equipments are designed for mechanical electrical life time test and vibration. All of test results satisfy the goal and the studied barrier shows the improved confidence.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.05a
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• pp.67-75
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• 1997

To establish testing method for ignition energy of explosive powders caused by electrostatic discharge, one testing method using a very small quantity of tested powders ( Frima ) was proposed, and the influence of discharge - limiting resistance connected in series into a capacitive discharge circuit on ignition energies of explosive powders was investigated using, as tested powders. As a result the minimum ignition energy was 9 mJ when discharge-limiting resistance was 300 k$\Omega$. The reason for the dependence of ignition energy on discharge-limiting resistance was thought to the difference in the type of electrostatic discharge, such as arc or glow discharge, from the observation of discharging wave forms.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2319-2324
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• 2011

Molecular structures and chemical properties of 1-aminoimidazole derivatives have been investigated at high levels of density functional theories. Heat of formation, density, explosive performances and impact sensitivities have been estimated at the global minimum of potential energy surface. As more nitro groups are introduced, the explosive performances of 1-aminoimidazole derivatives are enhanced, while the impact sensitivity becomes more sensitive. A two-dimensional plot between explosive performance and impact sensitivity has been utilized to comprehend the technical status of new explosive candidates. Based on locations in the two-dimensional plot, 1-aminodinitroimidzole isomers appears to have a potential to be good candidates for insensitive explosives, and 1-aminotrinitroimidazole may become a powerful explosive molecule whose behavior is quite close to HMX.

• Journal of Hydrogen and New Energy
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• v.30 no.1
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• pp.29-34
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• 2019

Safety of hydrogen handling facilities is needed as supply of hydrogen cars has been expanded recently. In this study, the adequacy of safety regulations of hydrogen handling facilities and the risk of damage with hydrogen leakage were studied. The range of explosion hazard location of the hydrogen filling plant was investigated using the computational fluid dynamics (CFD) method, Explosive hazardous area is influenced by leakage type, hole size and sectional area. When the conditions of KS standard are applied, range explosive hazardous area is expanded 7.05 m, maximum. It is about 7 times larger than exceptional standard of hydrogen station. Meanwhile, distance from leakage point to 25% LEL of hydrogen is investigated 1.6 m. Considering the shape of charging hose, regulation of hydrogen station is appropriate.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.16-22
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• 2012

We performed impact test to estimate necessary explosive charge weight for cutting the cable whose diameter is 22 mm. The impact test results were analyzed by Probit method. The cutting energy was calculated 37.7 J with 99.99% probability at 99% reliability compared to the average energy of 24.9 J. The cable was cut 3 times without failure with 150 mg of Zirconium Potassium Perchlorate (ZPP), which was considered to generate 24.5 J of mechanical energy with assumption that only 10% of explosive energy converts to mechanical energy. The calculated energy from measured pressure with 150 mg ZPP was 26.1 J, which is almost same with both impact test result and expected mechanical energy. We can argue that the cable can be cut with 99.99% probability at 99% reliability by 230 mg of ZPP.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.74-79
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• 1998

To establish measuring method for minimum ignition energy of explosive powders caused by electrostatic discharge, A measuring method(Hartman) using a very small quantity of pine tree testing powder was proposed, and the influence of discharge current limiting resistance connected in series into a capacitive discharge circuit on ignition energies of explosive powders was investigated. As a result the minimum ignition energy was 42.25mJ when discharge current limiting resistance 300 $k\Omega$.