• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.243-248
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• 2001

The present work is described the design factors and separation mechanism of ridge-cut explosive bolt in order to optimize the stage separation characteristics. Characteristics of test samples would differ depend on the detonating devices, the shape and size of bolt body, the amount of loading explosives, and the confinment conditions of bolt. Based on the results from these experimental factors, it appears to optimal condition of ridge-cut explosive that the amount of loading explosive seems to be near 110mg of RDX, the height of loading explosive is 3.5mm, the thickness of bolt is 3.9mm, and the degree of ridge is approximately $120^{\circ}$

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.532-543
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• 2004

The present work have been developed the interpretation processor including the behavior of material failure and the separation phenomena under transient dynamic loading (the operation of explosive bolt) using AUTODYN V4.3, SoildWork 2003 and TrueGrid V2.1 programs. It has been demonstrated that the interpretation in ridge-cut explosive bolt under dynamic loading condition should be necessary to the appropriate failure model and the basic stress of bolt failure is the principal stress. The use of this interpretation processor developing the present work could be extensively helped to design the shape and the amount of explosives in the explosive bolt having a complex geometry. It is also proved that the interpretation processor approach is an accurate and effective analysis technique to evaluate the separation mechanism in explosive bolts.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.42-47
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• 2004

Metallic glasses are amorphous meta-stable solids and are now being processed in bulk form suitable for structural applications including impact. Bulk metallic glasses have many unique mechanical properties such as high yield strength and fracture toughness, good corrosion and wear resistance that distinguish them from crystalline metals and alloys. However, only a few studies could be found mentioning the dynamic response and damage of metallic glasses under impact or shock loading. In this study, we employed a small explosive detonator for the dynamic indentation on a Zr-based bulk amorphous metal in order to evaluate the damage behavior of bulk amorphous metal under impact loading. These results were compared with those of spherical indentation under quasi-static and impact loading. The interface bonded specimens were adopted to observe the appearances of subsurface damage induced during indentation under different loading conditions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.447-451
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• 2002

The explosive compaction for processing of electrode material was realized based on axisymmetric loading scheme. The compression of internally oxidized fraction of the alloy Cu-0.15%BeO alloy did not provide a considerable strengthening effect; average microhardness varied from 130 to l50Mpa. The tensile strength comes to 30Mpa. However this method can be applicable to obtain a dense briquette for further extrusion of electrode.

• Explosives and Blasting
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• v.25 no.1
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• pp.45-52
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• 2007

When emulsion explosives(1kg/cartridge) are loaded into a long vertical borehole at open blasting site, they undergo an Impact corresponding to 117.6J of shock energy. After shocking. the crystallization of emulsion nay happen immediately. Furthermore, it nay cause a desensitization, arising from increase in the density of emulsion explosive by the breakage of sensitizer. In this paper, some experimental work was performed using PVC pipe equipment(50mm diameter and 12m lengths) to investigate the effects of loading impart of emulsion explosive. It is shown that detonation energy decreases up to 26% of the normal state value and this effect is less than 3% of the total performance of emulsion explosives in borehole blasting.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.273-282
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• 2023

Concrete construction, one of the oldest building practices, is commonly used in all parts of the world. Concrete is the primary building material for both residential and commercial constructions. The challenge of protecting the buildings, hence nation, against the attack of terrorism has raised the importance to explore the understanding of building materials against the explosion. In this research, a security check-post (reinforced concrete frame filled with plain cement concrete) has been chosen to study the behavior of structural elements under blast loading. Eight nitroglycerines-based dynamite blasts with varying amounts of explosive charge, up to 17 kg weight has been carried out at various scale distances. Pressure and acceleration time history records are measured using blast measuring instruments. Security check post after being exposed by explosive loading are photographed to view cracking/failure patterns on the structural elements. It is noted that with the increase of quantity of explosive, the dimensions of spalling and crack patterns increase on the front panels. Simple empirical analyses are conducted using ConWep and other design manuals such as UFC 3-340-02 (2008) and AASTP-1 (2010) for the purpose of comparison of blast parameters with the experimental records. The results of experimental workings are also compared with earlier researchers to check the compatibility of developed equations. It is believed that the current study presents the simple and preliminary procedure for calculating the air blast and ground shock parameters on the structures exposed to blast explosion.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.102-114
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• 2004

The present work has been developed the interpretation processor including the behavior of material failure and the separation phenomena under transient dynamic loading (the operation of explosive bolt) using AUTODYN V4.3, SoildWork 2003 and TrueGrid V2.1 programs. It has been demonstrated that the interpretation in ridge-cut explosive bolt under dynamic loading condition should be necessary to the appropriate failure model and the basic stress of bolt failure is the principal stress. The use of this interpretation processor developing the present work could be extensively helped to design the shape and the amount of explosives in the explosive bolt having a complex geometry. It is also proved that the interpretation processor approach is an accurate and effective analysis technique to evaluate the separation mechanism in explosive bolts.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.6
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• pp.857-866
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• 2013

This paper is concerned with the material properties of functional high explosive(FHX) simulant at various strain rates ranging from $10^{-4}/sec$ to $10^1/sec$. Material properties of FHX at high strain rates are important in prediction of deformation modes of FHX in a warhead which undergoes dynamic loading. Inert FHX stimulant which has analogous mechanical properties with FHX was utilized for material tests due to safety issues. Uniaxial tensile tests at quasi-static strain rates ranging from $10^{-4}/sec$ to $10^{-2}/sec$ and intermediate strain rates ranging from $10^{-1}/sec$ to $10^1/sec$ were conducted with JANNAF specimen using a tensile testing machine, INTRON 5583, and developed high speed material testing machine, respectively. Uniaxial compressive tests at quasi-static strain rates and intermediate strain rates were conducted with cylindrical specimen using a dynamic materials testing machine, INSTRON 8801. And cyclic compressive loading tests were performed with various strain rates and strains. Deformation behaviors were investigated using captured images obtained from a high-speed camera.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.19-22
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• 2003

For CHNO explosives, two new correlations of the form $P_{CJ}\;=\;8.7({\alpha}T_c')^{1/2}{\rho}_0^2-5\;and\;P_{CJ}\'=\'9.5({\alpha}T_c')^1/2{\rho}_0^2-9$ have been demonstrated, which relate detonation pressure, $P_{CJ}$; combustion temperature of the explosive in gas phase, $T_c$; combustion temperature of the explosive in crystalline state, $T_c'$; and the number of moles of gaseous products per unit weight of explosive, α; at initial density of the explosive, ${\rho}_0$. Experimental and semi-empirical PM3 procedures were used for the computation of $T_c$. Detonation pressures derived in this manner have a simple form without need to use computer code.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.1
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• pp.25-40
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• 2004

The supersonic shock wave generated by fully coupled explosion will change into subsonic shock wave, plastic wave, and elastic wave consecutively as the wave propagates through rock mass. While the estimation of the blast-induced peak pressure was the main aim of the companion paper, this paper will concentrate on the estimation of the rise time of blast-induced pressure. The rise time can be expressed as a function of explosive density, isentropic exponent, detonation velocity, exponential coefficient of the peak pressure attenuation, dynamic yield stress, plastic wave velocity, elastic wave velocity, rock density, Hugoniot parameters, etc. Parametric analysis was performed to pinpoint the most influential parameter that affects the rise time and it was found that rock properties are more sensitive than explosive properties. The probabilistic distribution of the rise time is evaluated by the Rosenblueth'S point estimate method from the probabilistic distributions of explosive properties and rock properties. Numerical analysis was performed to figure out the effect of rock properties and explosive properties on the uncertainty of blast-induced vibration. Uncertainty analysis showed that uncertainty of rock properties constitutes the main portion of blast-induced vibration uncertainty rather than that of explosive properties. Numerical analysis also showed that the loading rate, which is the ratio of the peak blasting pressure to the rise time, is the main influential factor on blast-induced vibration. The loading rate is again more influenced by rock properties than by explosive properties.