• Proceedings of the KSR Conference
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• 1999.11a
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• pp.146-154
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• 1999

The test facility of the 1/60-scale models for the train-tunnel interactions was recently developed to investigate the effects of entry portal shapes, flood shapes and air-shafts for reducing the micro-pressure waves radiating to the surroundings of the tunnel exits by KRRI in Korea. The launching system of train model was chosen as air-gun type. In present test rig, after train model is launched, the blast wave by the driver did not enter to inside of the tunnel model. The train model is guided on the one-wire system from air-gun driver to the brake parts of test facility end. Some cases of the experiments were compared with numerical simulations to prove the test facility.

• Journal of Auto-vehicle Safety Association
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• v.13 no.4
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• pp.73-80
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• 2021

Recently, Korea has established a plan for the supply of hydrogen vehicles and is promoting the expansion of the supply. Risk factors for hydrogen vehicles are hydrogen leakage, jet fire, and explosion. Therefore Safety measures are necessary for this hazard. In addition, risks in semi-closed spaces such as tunnels, underground roads, and underground parking lots should be analyzed. In this study, an explosion experiment was conducted on a hydrogen tank used in a hydrogen vehicle to analyze the risk of a hydrogen vehicle explosion accident that may occur in a semi-closed space. As results, the effect on the structure and the human body was analyzed using the overpressure and impulse values for each distance generated during the explosion.

• Explosives and Blasting
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• v.30 no.1
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• pp.29-36
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• 2012

In this study, the influence of priming location inside a blast hole on the ground vibration has been studied. In most of the previous studies dealing with the ground vibration, the effect of priming location in a blast hole was usually considered in a limited way. Thus, it seems that the results of the studies can be applicable only to the relevant sites. Considering the fact that the mechanism of ground vibration caused by blasting is quite complex, the priming location can have a considerable effect on the ground vibration in certain situations and be an important parameter in a blasting design. To identify the characteristics of the wave propagation according to priming locations, total 72 test blasts were carried out with different spacing, burden, drilling length, and charge, and prediction equations were derived. The characteristics of ground vibration, which was changed according to the priming location, was analyzed by using the nomogram of peak particle velocity (PPV) record. Attenuation relations, which were also dependent on the priming location, were analyzed. In this case, four different amounts of charge, that is, 0.5, 1.6, 5, and 15 kg, were used for the test. This criterion of charge amount is specified in the "Blasting design and construction guidelines to road construction" by the Ministry of Land, Transport and Maritime Affairs of Korea.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.77-81
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• 2010

D&B(Drill & Blast) method in tunnel construction requires accurate and rapid measurement of the ground movement, which is essential for feedback analysis. Case study and adaptability of IT technique for tunnel survey are discussed in this paper. The application of laserscannig and existing light wave instrument method in the field of tunnel construction were reported in several advanced country including Austria and Japan. Survey for the shoulder movements by IT survey method was conducted at a subway construction site and the results were compared to the conventional method. Also, the economic aspects of laserscannig method were analyzed using measured data which were categorized by expenses, frequency, interval and period in the field of construction. Therefore IT survey solution may contribute to execute more economic and safe construction

• Journal of the Korea Institute of Building Construction
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• v.20 no.3
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• pp.279-287
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• 2020

Recently, the demand for underground-type ammunition storage facilities has increased. Comparing with a ground-type ammunition storage facility, the underground-type ammunition storage facility can decrease the standard of safety distance because fragment and blast wave can be locked in the rock formation. However, the absence of a design method on the underground-type ammunition storage chamber became a major setback for the construction promotion. In this study, the process for designing an overall configuration of the underground-type ammunition storage facility was provided. First, the determination method for configuration and number of the chamber was developed by performing the ammunition storage simulation. Then, a tunnel (i.e., transfer channel for vehicles) and designed chambers can be arranged on the basis of safety distance standard. The safety distance standard also should be considered for determining the location and the size of entrances because of the blast wave and fragment effect at the entrances when an explosion is generated inside a chamber. In addition, considerations on the design for the waterproof and the drainage of subsurface water were analyzed through construction cases. Finally, an example of designing underground-type ammunition storage chambers was provided in order to verify the developed design process.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.52-65
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• 2021

In this study, authors analyzed the vapor cloud explosion induced by propane leak at the PEMIX Terminal, which is the propane storage facility outside of Mexico City. TNT equivalence mass for the leaked 4750 kg propane was estimated to be 9398 kg. Blast parameters such as peak overpressure, positive phase duration, and impact at 40-400 (m) away from the center of the explosion were calculated by applying TNT Equivalency Method and Multi-Energy Method. The probability of damage due to lung damage, eardrum rupture, head impact, and whole-body displacement impact by applying the probit function obtained using blast parameters was evaluated. The peak overpressure obtained using Multi-Energy Method was found to be greater than the peak overpressure obtained by applying the TNT Equivalency Method at all distances considered, but it was evaluated that there was no significant difference from the points above 200 m. The peak overpressure obtained by Multi-Energy Method was computed to assess the extent of damage to the structure, and it was shown that structures within 100 m of the explosion center would collapse completely, and that the glasses of the structures 400 m away would be almost broken. The probability of death due to lung damage was shown to vary depending on a human body's position located in the propagating direction of shock wave, and if there is a reflecting surface in the immediate surroundings of a human body, the probability of death was estimated to be the greatest. The impact of shock wave on lung damage, eardrum rupture, head impact, and whole-body displacement impact was evaluated and found to affect whole-body impact < lung damage < eardrum rupture

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.510-517
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• 2016

Supersonic jet technology using high pressures has been popularly utilized in diverse industrial and engineering areas related to working fluids. In this study, to consider the effects of a shock wave caused by supersonic jet flow from a high pressure pipe, the SST turbulent flow model provided in the ANSYS FLUENT v.16 was applied and the flow characteristics of the pressure ratio and Mach number were analyzed in accordance with the working fluids (air, oxygen, and hydrogen). Before carrying out CFD (Computational Fluid Dynamics) analysis, it was presumed that the inlet gas temperature was 300 K and pressure ratio was 5 : 1 as the boundary conditions. The density function was derived from the ideal gas law and the viscosity function was derived from Sutherland viscosity law. The pressure ratio along the ejection distance decreased more in the lower density working fluids. In the case of the higher density working fluids, however, the Mach number was lower. This shows that the density of the working fluids has a considerable effect on the shock wave. Therefore, the reliability of the analysis results were improved by experiments and CFD analysis showed that supersonic jet flow affects the shock wave by changing shape and diameter of the jet, pressure ratio, etc. according to working fluids.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.60-65
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• 2015

In this paper, we used the sound of gunshots recorded by multiple microphones to increase the accuracy of the calculation of the distance between sniper and the microphone array. This method is crucial for achieving military objectives. Gunshots are comprised of the explosion of driving gas from the muzzle and the supersonic shock wave from the flying bullet. The original distance calculation method compares the time difference of arrival and angle of incidence to estimate the sniper's location. The disadvantage of this method is that when the angles of incidence coincide the margin of error increases, to solve this problem we suggest a new method using the characteristic changes of the shock wave with the increase of perpendicular distance between the microphone and the trajectory of the bullet. This theory is verified by experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.58-71
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• 2009

The blast wave released during the initiation of energetic materials gives rise to pulse energy generation, characterized by a sudden increase of potential energy. A highly efficient energy source, sought from pulse-type lasers, may be utilized in various space propulsion and power applications. This paper introduces a scheme of utilizing the laser energy in 1) attitude control of a satellite requiring of a low thrust, 2) innovative laser-induced drug delivery, 3) implosion-based micro piston development, 4) deflecting and zapping of space debris for laser kill purpose, and 5) finally lunar detection using laser induced breakdown spectroscopy.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.188-193
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• 2009

Fuel cell vehicles are equipped with Pressure Relief Devices(PRDs) installed in pressure tank cylinder to prevent the explosion of the tank during a fire. PRDs are safety devices that perceive a fire and release gas in the pressure tank cylinder before it is exploded. But if the PRD does not actuate, because either the PRD fails or can't be surrounded by the flame of a fire, the tank will rupture and produce a blast wave and hydrogen fire ball. In this paper, we observed the fire behavior of actual fuel cell vehicle, comparing with that of gasoline vehicle.