• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2319-2324
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• 2011

Molecular structures and chemical properties of 1-aminoimidazole derivatives have been investigated at high levels of density functional theories. Heat of formation, density, explosive performances and impact sensitivities have been estimated at the global minimum of potential energy surface. As more nitro groups are introduced, the explosive performances of 1-aminoimidazole derivatives are enhanced, while the impact sensitivity becomes more sensitive. A two-dimensional plot between explosive performance and impact sensitivity has been utilized to comprehend the technical status of new explosive candidates. Based on locations in the two-dimensional plot, 1-aminodinitroimidzole isomers appears to have a potential to be good candidates for insensitive explosives, and 1-aminotrinitroimidazole may become a powerful explosive molecule whose behavior is quite close to HMX.

• 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.7 no.3 s.18
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• pp.122-128
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• 2004

Internal blast performance test on developed explosives was carried out. Internal blast means a blast wave in closed chambers like tunnels, bunkers, operation center and chamber of ships. We used Anpa tunnel for our test facility. We performed two series of tests to measure internal blast of developed explosives. Three different kinds of cast PBXs, DXD-09, DXD-10, DXD-18, and conventional explosive, Tritonal, were used in our test. The explosives were cast as a charge of 108mm diameter in a plastic tube of a 3mm thickness. The length of charges 4ere adjusted as a weight 3kg. A melt-cast explosive, tritonal, was used as a reference. Pentolite booster was used. The cylindrical boosters have a 95mm diameter and 47.5mm height. The results showed that there may be some differences between the performances in the air blast tests and those in the internal blast tests. The results showed that DXD-10, the best performance in air blast tests, showed the poorest performance in internal blast among the explosives tested. On the other hand, DXD-18 showed exactly the opposite trend. This is probably due to the highest contents of aluminum and inert binder in DXD-18. DXD-18 has $38\;wt\;\%$ of aluminum and $17\;wt\;\%$ of inert binders.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1764-1767
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• 2002

Recent explosive increases in information 'volume have led to a rapid development or a change of information technology which stores, searches, and manages a vast amount of information. It is considered that an effective share and utilization of a large amount of digital information produced by work performances is a pivotal element which can make decisive contributions to a great success of business management. This common property of information reflects a changing social paradigm including a change of business processes. This paper is aimed at designing and embodying the construction of knowledge base in an efficient project management system using unsupervised data mining techniques in order to extract information and utilize it as knowledge about standard data (statistical data, template etc.,), size prediction and a danger precaution notice which are needed for a plan and a scheduling of a new project from data coming from already-established projects.

• Explosives and Blasting
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• v.36 no.3
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• pp.19-28
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• 2018

Locally damaged structures caused by earthquake or extraordinary external forces have been required to rapidly be dismantled because of its possibility of additional collapses. Particularly, steel frame structures were demolished by the shaped charge blasting method. Recently a research suggested a shape charge blasting technique which uses bent-shaped charge holder of copper plate and emulsion explosive charge to cut thick steel plates. This study simulated the cutting performance of the bent-shaped charge holder with considering types of explosives, thickness of copper liner and stand-off distances using LS-DYNA software. The shape charge blasting test of a 25mm thickness steel plate were used to calibrate the input parameters of the numerical models. The penetration depth and penetration width were analysed with different types of explosives, thickness of copper liner and stand-off distances.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2257-2262
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• 2014

$C_{60}$ is widely investigated because of its unique structure. But its applications in solid propellant seem to be relatively neglected. $C_{60}$ has more outstanding features than carbon black which is widely used as a catalyst ingredient of solid propellant. To combine the advantages of fullerene and lead salts, another good composite in propellant catalysts, we synthesized a kind of fullerene phenylalanine lead salt (FPL) and explored its thermal performances by differential thermal analysis (DTA) and thermogravimetry analysis (TGA). The results show it undergoes four exothermic processes started from 408 K. Combined TGA and X-ray diffractometer (XRD), the decomposition mechanism of FPL was derived by TG-IR and comparing IR spectra of FPL and its residues after burned to $327^{\circ}C$, $376^{\circ}C$ and $424^{\circ}C$, respectively. Effect of FPL on the decomposition characteristic of hexogen (RDX), a type of explosive in propellant, has been investigated using DTA at different heating rate, which shows the decomposition temperatures of the explosive are all reduced by more than 20 K. The corresponding activation energy ($E_a$) is decreased by $30kJ{\cdot}mol^{-1}$. So FPL has potential application as a combustion catalyst in solid propellant.

• Journal of Digital Convergence
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• v.16 no.9
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• pp.239-245
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• 2018

In the current mainstream pop music scene, Stevie ray vaughan's status is a singer-songwriter and electric blues guitarist, who occupies a very large position despite his short period of activity. His influence has remained to the present day as the voice of many guitarists ranging from his unique sound to his explosive stage performances. Let's take a look at the technical parts of his performance, rhythm and solo performances, among the various traces of his constant reproduction. Based on one of his most famous works, 'Pride and Joy' I analyzed the solo and rhythm, scale that Stevie Ray Vaughan played. Through the African American blues, a peripheral heritage he has been trying to influence and influence, how his traces congregate in the center of today's mainstream pop music scene. This will give us little clues to appreciate before the research that will have a variety of influences and values.

• Journal of KIISE
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• v.43 no.8
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• pp.927-932
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• 2016

With the explosive increase in the number of online medical documents, the demand for question-answering systems is increasing. Recently, question-answering models based on machine learning have shown high performances in various domains. However, many question-answering models within the medical domain are still based on information retrieval techniques because of sparseness of training data. Based on various information retrieval techniques, we propose an answer snippet retrieval model for question-answering systems of medical documents. The proposed model first searches candidate answer sentences from medical documents using a cluster-based retrieval technique. Then, it generates reliable answer snippets using a re-ranking model of the candidate answer sentences based on various sentence retrieval techniques. In the experiments with BioASQ 4b, the proposed model showed better performances (MAP of 0.0604) than the previous models.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.718-724
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• 2014

Insensitive Munition(IM) reduces the explosive weakness of munitions, at the same time, maintains its performances in the moment of discharge, which improves safety of soldiers and minimizes unexpected accidents and casualties from being shot in case of transportation, storage and military operation. Development of IM has been focused as the global trend, which was required to satisfy the demand of army that is to minimize the loss of non-battle forces and to retain the competitiveness in export abroad. In this study, we categorize all the munitions used by ROK Army, then determine the priority of IM by deploying AHP(Analytic Hierarchy Process) method. In conclusion, we suggest the priority of IM which is suitable to the affairs of ROK Army.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1913-1918
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• 2012

The nitramine explosives with $-NH_2$ and -F groups were optimized to obtain their molecular geometries and electronic structures at DFT-B3LYP/6-31+G(d) level. The theoretical molecular density (${\rho}$), heat of formation (HOF), detonation velocity ($D$) and detonation pressure ($P$), estimated using Kamlet-Jacobs equations, showed that the detonation properties of these compounds were excellent. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were respectively related with the temperature. The simulation results reveal that 1,3,5,7-tetranitro-1,3,5,7-tetrazocan-2-amine (molecule B1) performs similarly to the famous explosive HMX, and 2-fluoro-1,3,5-trinitro-1,3,5-triazinane (molecule C1) and 2-fluoro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (molecule D1) outperform HMX. According to the quantitative standard of energetics and stability as an HEDC (high energy density compound), molecules C1 and D1 essentially satisfy this requirement. These results provide basic information for molecular design of novel high energetic density compounds.