• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.89-97
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• 2002

In this study, the effect of $\alpha$-phase morphology on the dynamic deformation behavior at ultra high strain rate was investigated by EBW(Explosive Bridge Wire) test. All of tests and analyses were conducted on three typical microstructures of Ti-6Al-4V alloy, i.e. equiaxed, widmanstatten and bimodal microstructures. The spall strength and HEL(Hugoniot Elastic Limit) of the specimens that have the thickness of 2mm and 4mm were highest with the bimodal microstructure. These results were similar with previous study which was performed by dynamic torsion test(Kolsky torsion test).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.155-156
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• 2018

In this study, surface spalling and explosive spalling of ring-type ultra-high strength concrete under rapid heating and slow heating were investigated. In rapid heating, the internal temperature difference of the concrete is large, so that continuous surface spalling occurs. However, in slow heating, the difference in the internal temperature of the concrete is small, resulting in explosive spalling at a time. Since the heating condition has a great influence on the internal temperature of the concrete, it is necessary to consider the spalling of the concrete under various heating conditions.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.1
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• pp.108-115
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• 2003

TNAZ is a high explosive material because it is a highly strained ring compound containing one nitramine and gem dinditro groups. 1-t-butyl-3-nitroazetidine which was used as an intermediate previously, which declined the overall yield in synthesizing TNAZ. We obtained 1-t-butyl-3-hydroxymethyl-3-nitroazetidine in 64% yield from advances process which was used in synthesis of 1-t-butyl-3-nitroazetidine. The reaction pathway, shortening of reaction time, together with improvement of yield were studied too. We have obtained TNAZ in 85% yield.

• Magazine of the Korea Concrete Institute
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• v.17 no.3 s.86
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• pp.33-39
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• 2005

• Magazine of the Korea Concrete Institute
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• v.20 no.5
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• pp.26-32
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• 2008

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.935-940
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• 2008

When reinforced concrete is subjected to high temperature as in fire, there is deterioration in its properties of particular importance are loss in compressive strength, cracking and spalling of concrete, destruction of the bond between the cement paste and the aggregates and the gradual deterioration of the hardend cement paste. Assessment of fire-damaged concrete usually starts with visual observation of color change, cracking and spalling of the surface. In this paper, it was reported the trends of research and practical use on the Explosive Spalling Properties and Performance Based of Structural Design of the High-Strength Concrete.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.91-97
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• 2014

purpose of this study was to conduct status survey on existing shelter facilities for residents and use it as basic material to plan and design improved shelter facilities in the future. As the result, first, although existing shelter facilities are judged to have been designed in consideration only of the protection from high explosive shells, actual protection capability is significantly low against high explosive shells when exit direction and protection capabilities of main entrances were investigated. Second, all the 7 facilities did not have air purifier with filters installed for the air that flows into the inside from outside and since the height of air exhausts and intake pipes in the outside are also close to the earth, there are possibilities that heavy contaminated air can flow into the inside. Third, although some facilities have anti-explosion doors installed, it is impossible to use them as chemical, biological and radiological (CBR) shelter because of improper installation of openings and anti-explosion valves as well as poor plumbing that cannot ensure air-tightness and poor finish of piping penetration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.423-425
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• 2017

When many space launchers and rockets need to be separated, the pyrotechnic separators have been widely used because of their high reliability and high energy generation. However, intensive pyroshock and debris from the high-explosive type separator may cause fatal damage to the equipment inside of the space launchers or rockets. To solve this problem, a pressure-cartridge type low-impact separator has been developed. In this study, one of the low-impact separators, the split-type pyrolock, was used. We established a mathematical model for the split-type pyrolock that simulates the state of combustion gas and the separation behavior of four independent internal components and verified the mathematical model through comparing with experiment results.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.510-517
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• 2019

Increasing proliferation resistance of plutonium by way of increased $^{238}Pu$ content is of interest to the nuclear nonproliferation and international safeguards community. Considering the high alpha decay heat of $^{238}Pu$, increasing the isotopic fraction leads to a noticeably higher amount of heat generation within the plutonium. High heat generation is especially unattractive in the scenario of weaponization. Upon weaponization of the plutonium, the plutonium may generate enough heat to elevate the temperature in the high explosives to above its self-explosion temperature, rendering the weapon useless. In addition, elevated temperatures will cause thermal expansion in the components of a nuclear explosive device that may produce thermal stresses high enough to produce failure in the materials, reducing the effectiveness of the weapon. Understanding the technical limit of $^{238}Pu$ required to reduce the possibility of weaponization is key to reducing the current limit on safeguarded plutonium (greater than 80 at. % $^{238}Pu$). The plutonium vector evaluated in this study was found by simulating public information on Lightbridge's fuel design for pressurized water reactors. This study explores the temperature profile and maximum stress within a simple (first generation design) hypothetical nuclear explosive device of four unique scenarios over time. Analyzing the transient development of both the temperature profile and maximum stress not only establishes a technical limit on the $^{238}Pu$ content, but also establishes a time limit for which each scenario would be useable.

• 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.