• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.3
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• pp.41-48
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• 2005

The purpose of this study is to improve the performance of jet set cement, which mixed with the mineral admixtures such as silica fume, fly ash and ground granulated blast furnace slag. First, the test of mortar according to the substitute ratio of mineral admixtures were evaluated. And then using it obtained from test results, it was conducted with experiment of mechanical, physical and permeable characteristics of concrete. Laboratory test results showed that concrete substituted for $5\%$ of silica fume didn't have an effect on prominent performance relating to compressive strength. However it was superior to concrete in case of resistance of chloride permeation.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.360-366
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• 2016

The Propulsion Test Facilities for the development of Korea Space Launch Vehicle-II are being built, some test facilities are completed and various combustion tests are running. The Propulsion Test Facilities consists test-stand, which carries out tests for engine development model, and various sub-systems and vessels containing LOX and Jet A-1 as propellant. There are always risks of fire and explosion at the test-stand since engine development model is conducted at test-stand with real combustion test with very high pressure, mixed propellant and high energy. In this paper, in order to establish the consequence analysis and risk reduction measures in the Propulsion Test Facilities, followings are considered. 1) a propellant leak accident scenario is assumed in test-stand. 2) TNT equivalent model equation based on blast wave of the explosion was used to analyze blast overpressure and impacts. Also, technical, systematic and managemental measure is described to ensure risk reduction for propulsion test facility.

• Journal of computational fluids engineering
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• v.19 no.4
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• pp.68-74
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• 2014

This computational study features the transient compressible and inviscid flow analysis on a metallic plasma discharge from the opposing composite electrodes which is subjected to pulsed electric power. The computations have been performed using the flux corrected transport algorithm on the axisymmetric two-dimensional domain of electrode gap and outer space along with the calculation of plasma compositions and thermophysical properties such as plasma electrical conductivity. The mass ablation from aluminum electrode surfaces are modeled with radiative flux from plasma column experiencing intense Joule heating. The computational results shows the highly ionized and highly under-expanded supersonic plasma discharge with strong shock structure of Mach disk and blast wave propagation, which is very similar to muzzle blast or axial plasma jet flows. Also, the geometrical effects of composite electrodes are investigated to compare the amount of mass ablation and penetration depth of plasma discharge.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1494-1498
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• 2007

Impulsive shooting noise is basically complex phenomenon which contains the linear and non-linear characteristics. For those reasons, numerical analysis of impulsive shooting noise has the difficulties in control of the numerical stability and accuracy on the simulation. In this research, Wave-number Extended Finite Volume Scheme (WEFVS) is applied to the numerical analysis of impulsive shooting noise. In the muzzle blast flow simulation, the generation of the precursor wave and the induced vortex ring are observed. Consequently, blast wave. vortex ring interaction and vortex ring. bow shock wave interaction are evaluated on the shooting process using the accurate and stable scheme. The sound generation in the interactions can be explained by the vorticity transport theorem. The shear layer is evolved behind the projectiles due to the jet flow. In these computations, the impulsive shooting noise is generated by the complex interaction with shooting process and is propagated to the far-field boundary. The impulsive shooting noise generation can be observed by the applications of WEFVS and analyzed by the physical phenomena.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2425-2433
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• 2011

DSM (Deep Soil Mixing) is to establish soil-cement column by injecting of cement slurry and blending it in soft ground and have been introduced to Singapore in 1980s and now a days quite popular and considered as alternative method to the jet grouting for temporary earth retaining works and foundations. Herein this paper, the results of lab mixing test based on comparison of characteristics between OPC (Original Portland Cement) and PBFC (Portland Blast Furnace Slag Cement), DSM field trial test and main installation results including monitoring, was presented and it would be referred to similar site later.

• 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.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.38-45
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• 2018

Jet fire, pool fire, and vapor cloud explosion are major accident scenarios in LPG filling station. The protection wall would mitigate radiation effect in a jet fire. In case of a pool fire, the protection wall would restrict expanding the pool area. The protection wall might both obstruct the dispersion of released vapor and protect blast overpressure in a vapor cloud explosion scenario. In this paper, An availability assessment method of the protection wall how much reduce damage to receptors is proposed. Additionally application cases are presented for the effectiveness of protection wall in the LPG filling station. The study shows that the protection wall can effectively reduce the death probabilities of receptors located behind the wall in cases of the jet fires and the vapor cloud explosions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.386-393
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• 2005

The objective of the present study is to develop a new type of the Ballistic range, called 'two-stage light gas gun'. A computational work has been performed to investigate the aerodynamics of a projectile which is launched from the two-stage light gas gun. A moving coordinate method for a multi-domain technique is employed to simulate unsteady projectile flows with a moving boundary. The effect of a virtual mass is added to the axisymmetric unsteady Euler equation systems. The computed results reasonably capture the major flow characteristics which are generated in launching the projectile supersonically, such as the interaction between the shock wave and the blast wave, the interaction between the vortical flow and the barrel shock, and the steady under-expanded jet. The present computational results properly predict the velocity, acceleration, and drag histories of the projectile.

• 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.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.419-427
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• 2024

This study assessed the potential impact of gas leakage resulting from accidental damage to buried urban gas pipelines during perforating operation near subway construction sites. The risk of explosions due to ignition sources such as static electricity, arising from gas infiltrating the subway construction site through storm sewers and sewage pipes, was evaluated using the ALOHA program. The results of the threat zone calculation, which input various parameters of urban gas pipelines such as length, diameter, and pressure, indicated that the flammable area within the vapor cloud extended from 1.2 to 1.4 km (red zone), the blast area ranged from 0.8 to 1.0 km (yellow zone), and the jet fire extended from 45 to 61 m (red zone). This study demonstrates that within the flammable area of the vapor cloud, a specific combination of concentration and conditions can increase flammability. The blast area may experience explosions with a pressure of 1.0 psi, sufficient to break glass windows. In the event of a jet fire, high temperatures and intense radiant heat exposure lead to rapid fire propagation in densely populated areas, posing a high risk of casualties. The findings are presented in terms of the sphere of influence and threat zone ranges.