• Explosives and Blasting
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• v.19 no.1
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• pp.101-110
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• 2001

Depleted uranium (DU) outperforms tungsten heavy alloys (WHA) by about 10%. Because of environmental and hence, political concerns, there is a need to improve WHA performance, in order to replace the DU penetrators. A technique of metal powder compaction by the detonation of an explosive has been applied to tungsten-titanium(W-Ti) powder materials that otherwise may be difficult to fabricate conventionally or have dissimilar, nonequilibrium, or unique me1astab1e substructures. However, the engineering properties of compacted materials are not widely reported and are little known especially for the "unique" composition of W-Ti alloy. To develop high-performance tungsten composites with superior ballistic attributes, it is necessary to understand, carefully document controlled experimental results, and develop basic computational models for potential composites with controlled microstructures. A detailed understanding and engineering application of W-Ti alloy can lead to the development of new structural design for engineering components and materials.

• Explosives and Blasting
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• v.14 no.4
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• pp.4-12
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• 1996

In '50, It was turnning point of tunneling technology that v-cut of single Face replaced by Burn cut.. Which was a standard Blasting formula. In '70, We faced Seoul Sub-Way construction by NATM. As it was damages to the Structure on the surface, finally we made empirical formula. For Granite $V=kw^{0.57}D^{1.75}$ For Grneiss $V=KW^{0.5}D^{1.75}$ For Concrete breaker $V=KW^{0.5}D^{1.75}$ (K=7) The magnitude of groun vibration can be reduced as using follow matters. First, by using explosive that have low dencity and low Velocity of detonation. Second adopting two stage deck charging, third, by using Milli Second electric Caps and Multi-Sequency blasting machine.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.283-286
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• 2012

The analytical model determining the unknown parameters of reaction rate equation which is necessary to simulate the combustion phenomena of energetic materials is proposed. The relationship between detonation velocity and size effect of energetic materials is derived from simplified JWL++ model. Theoretical model is used to investigate the combustion characteristics of certain energetic materials before running Hydrocode by pre-determination of unknown parameter, b. When b=0.8, the behavior of HANFO gunpowder is in the form of concave-up and ANFO explosives has the concave-down form in case of b=1.5. The analytical model provides efficient and highly accurate results rather than previous method which simulated the unconfined-rate-stick via the numerical means.

• Analytical Science and Technology
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• v.28 no.5
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• pp.347-352
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• 2015

Chemical properties such as heat of formation and density of methylnitroimidazole derivatives were predicted and analyzed by using density functional theory (DFT). Successive addition of energetic nitro groups into an imidazole ring increases both the heat of formation and the density. Using the chemical property values computed by DFT, explosive performance was analyzed with the Cheetah program, and compared with those of TNT, RDX, and HMX, which are currently used widely in military systems. When both C-J pressure and detonation velocity were used as explosive performance, methyldinitroimidazole derivatives show better performance than TNT, while methyltrinitroimidzole is almost close to RDX. Since methylnitroimidazole derivatives have a good merit, i.e. low melting point for melt loading, they are forecasted to be used widely in various military and civilian application.

• Journal of Industrial Technology
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• v.3
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• pp.17-26
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• 1983

The blast vibrations were measured from 10 places through Seoul subway area to study their effects on the structures and to establish the safe blasting limits. For purpose of the present study, particle velocity only was recorded and analyzed, because it correlated most directly with damage. The results are as follows: (1) The proagation equation, $V=K(D/W^{1/3})^{-n}$ was obtained. Typical values could be found for n range from 1.7 to 1.5 and for k range from 48 to 138. (2) From the relationship between schmidt hammer rebound hardness and uniaxial compressive strength, $Sc=0.514{\times}(S.H)^{0.23}$, the compressive strength at any area can be assumed. (3) The use of AN-FO and other explosives with low detonation pressure may reduce vibration levels generated.

• Explosives and Blasting
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• v.34 no.2
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• pp.31-38
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• 2016

The hydrodynamics code is a numerical tool developed for modeling high velocity impacts where the materials are assumed to behave like fluids. The hydrodynamics code is widely used for solving impact problems, such as rock blasting using explosives. For a realistic simulation of rock blasting, it is necessary to model explosives numerically so that the interaction problem between rock and explosives can be solved in a fully coupled manner. The equation of state of explosives, which describes the state of the material under given physical conditions, should be established. In this paper, we introduced the hydrodynamics code used for explosion process modeling, the equation of state of explosives, and the determination of associated parameters.

• Explosives and Blasting
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• v.38 no.2
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• pp.13-21
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• 2020

The shaped charge was used in explosive demolition of a steel frame structure, but it was often not used because it was limited to use and impossible to supply at domestic and overseas. Existing linear shaped charge did not have sufficient cutting performance to cut steel frame structures with a huge scale and thick steel plate. To solve these problems, we produced a device that could generate metal jets using industrial explosives of high detonation velocity and pressure. In this study, we made a charging container of three types which applicable to explosive demolition of steel frame structures. The experiment of cutting performances was carried out to evaluate the effect of cutting of charging containers on the various thicknesses of the H-beam and steel plate. As a result of the experiment, sufficient cutting performance was confirmed.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.229-236
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• 2020

A crush switch assembly(CSA) connected to an impact fuze provides electrical signal for detonation of the loaded main charge when an impact with the target is detected. Because the CSA experiences continuous changes in flight environment such as changes in velocity, vibration, and stresses, it is necessary to accurately predict the behavior of the fuze to maintain functionality during flight and to detonate when necessary. In this paper, random vibration analysis for flight environment and impact analysis on target hit are performed using FEA. Then, high speed impact tests are performed with the original and scaled down models to ensure operation validation of the manufactured products. The test results are then compared with M&S results to verify the capability of currently modeled CSA.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.289-300
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• 2020

Estimating the damage induced by an explosion around a blast hole has always been a challenging issue in geotechnical engineering. It is difficult to determine an exact dimension for damage zone since many parameters are involved in the formation of failures, and there are some uncertainties lying in these parameters. Thus, the present study adopted a probabilistic approach towards this problem. First, a reliability model of the problem was established and the failure probability of induced damage was calculated. Then, the corresponding exceedance risk curve was developed indicating the relation between the failure probability and the cracked zone radius. The obtained risk curve indicated that the failure probability drops dramatically by increasing the cracked zone radius so that the probability of exceedance for any crack length greater than 4.5 m is less than 5%. Moreover, the effect of each parameter involved in the probability of failure, including blast hole radius, explosive density, detonation velocity, and tensile strength of the rock, was evaluated by using a sensitivity analysis. Finally, the impact of the decoupling ratio on the reduction of failures was investigated and the location of its maximum influence was demonstrated around the blast point.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.3
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• pp.96-102
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• 2015

Traditional propellants emit toxic gases such as carbon dioxide and hydrogen chloride during combustion which are harmful to the environment. This study established a synthetic process of a high nitrogen containing derivative of tetrazine, 3,3-Azobis(6-Amino-1,2,4,5-Tetrazine) (DAAT), which can be applied as solid fuels for a solution to environmental concerns. Also, this paper described the detailed process and the analytic results of properties, which were not mentioned in previous reports. The compound was characterized by NMR, IR spectroscopy, and thermal, impact, and friction stability were measured. In addition, the heats of formation (${\Delta}H_f$) and detonation properties (pressure and velocity) of DAAT were calculated using Gaussian 09 and EXPLO5 programs.