• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.267-276
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• 2022

Modelling the energy release performance of energetic material combustion in closed systems is of fundamental importance for aerospace and defense application. In particular, to compensate for the disadvantage of the combustion of single energetic material and maximize the benefits, a method of combusting the mixed energetic materials is used. However, since complicated heat transfer occurs when the energetic material is combusted, it is difficult to theoretically predict the combustion performance. Here, we suggest a theoretical model to estimate the energy release performance of mixed energetic material based on the model for the combustion performance of single energetic material. To confirm the effect of parameters on the model, and to gain insights into the combustion characteristics of the energetic material, we studied parameter analysis on the reaction temperature and the characteristic time scales of energy generation and loss. To validate the model, model predictions for mixed energetic materials are compared to experimental results depending on the amount and type of energetic material. The comparison showed little difference in maximum pressure and the reliability of the model was validated. Finally, we hope that the suggested model can predict the energy release performance of single or mixed energetic material for various types of materials, as well as the energetic materials used for validation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.311-319
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• 2008

We present an innovative method of multi physics application involving energetic materials. Energetic materials are related to reacting flows in extreme environments such as fires and explosions. They typically involve high pressure, high temperature, strong shock waves and high strain rate deformation of metals. We use an Eulerian methodology to address these problems. Our approach is naturally free from large deformation of materials that make it suitable for high strain rate multi-material interacting problems. Furthermore we eliminate the possible interface smearing by using the level sets. We heave devised a new level set based tracking framework that can elegantly handle large gradients typically found in reacting gases and metals. We show several work-in-progress application of our integrated framework.

• Particle and aerosol research
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• v.9 no.3
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• pp.173-185
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• 2013

Oxidations of metal generate large quantity of thermal and light energies but no toxic pollutants, so that metals with high calorific values, such as beryllium, boron, aluminum, magnesium, and lithium, are possible to be used as clean fuels instead of fossil fuels. However, they are so explosive due to very high oxidation rates that they should be stabilized by their surface passivation with oxides, organics and inorganics. For reasonable use of energetic metal particles as solid fuel, therefore, some detail information, such as thermal properties, preparation and passivation methods, and application area, of the energetic metals is introduced in this manuscript.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1860-1865
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• 2019

The confinement degradation of the energetic particles during RMP would be a key issue in success of realizing the successful energy production using fusion plasma, because a 3.5 MeV energetic alpha particle should be able to sustain the burning plasma after the ignition. As KSTAR recent results indicate the generation of high-performance plasma(${\beta}_p{\sim}3$), the confinement of the energetic particles is also an important key aspect in neutral beam driven plasma. In general, the measured absolute value of the neutron intensity is generally used for to estimating the confinement time of energetic particles by comparing it with the theoretical value based on transport calculations. However, the availability of, but for its calculation process, many accurate diagnostic data of plasma parameters such as thermal and incident fast ion density, are essential to the calculation process. In this paper, the time evolution of the neutron signal from an He3 counter during the beam blank has permitted to facilitate the estimation of the slowing down time of energetic particles and the method is applied to investigate the fast ion effect on ELM suppressed KSTAR plasma which is heated by high energy deuterium neutral beams.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.571-579
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• 2009

For the flow analysis of reactive compressible media involving energetic materials and metallic confinements, a Hydro-SCCM (Shock Compression of Condensed Matter) tool is developed for handling multi-physics shock analysis of energetics and inerts. The highly energetic flows give rise to the strong non-linear shock waves and the high strain rate deformation of compressible boundaries at high pressure and temperature. For handling the large gradients associated with these complex flows in the condensed phase as well as in the reactive gaseous phase, a new Eulerian multi-fluid method is formulated. Mathematical formulation of explosive dynamics involving condensed matter is explained with an emphasis on validating and application of hydro-SCCM to a series of problems of high speed multimaterial dynamics in nature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.238-241
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• 2007

We present an innovative method of multi-physics application involving energetic materials. Energetic materials are related to reacting flows in extreme environments such as fires and explosions. They typically involve high pressure, hish temperature, strong non-linear shock waves, and high strain rate deformation of metals. We use an Eulerian methodology to address these problems. Our approach is naturally free from large deformation of materials that makes it suitable for high strain-rate multi-material interaction problems. Furthermore we eliminate the possible interface smearing by using the level sets. We have devised a new level set based tracking framework that can elegantly handle large gradients typically found in reacting gases and metals. We show several work-in-progress applications of our algorithm including the Taylor impact test, explosive venting and additional confined explosion problems of modem interest.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.274-278
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• 2011

We present an innovative method of multi-physics application involving energetic materials. We use an Eulerian methodology to address these problems. We have devised a new level set based tracking framework that can elegantly handle large gradients typically found in energetic response of high explosive and metals. Proper constitutive relations are employed to model the transient phases of gas, lliquid, and solid in the high strain rate regime. We use the confined and unconfined rate stick results to validate against the experimental data.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.77-87
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• 2006

Micro- or nano-size particles are required to improve the combustion efficiency and stability in the case of solid explosives and propellants. The micro-structural properties of an energetic material strongly influence the combustion and explosion behavior. However, the traditional size reduction techniques, including milling, are not suitable for production of ultra-fine size particles. As an alternative to the traditional techniques, various re-crystallization processes based on supercritical fluids have recently been proposed. Supercritical fluids are fluids at temperatures and pressures above their critical point. In principle, they do not give problems of solvent contamination as they are completely released from the solute when the decompression occurs. Rapid Expansion Supercritical Solutions(RESS) and Supercritical Anti-Solvent Process(GAS/SAS) are representatives of a nano-size particle formation process of energetic materials using supercritical fluids. In this work, various fine particle formation processes using supercritical fluids are discussed and the results are presented.

• Particle and aerosol research
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• v.10 no.4
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• pp.177-182
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• 2014

In this study, nickel-coated aluminum (Ni/Al) powders were synthesized for the utilization of energetic applications. Oxide materials present at the surface of Al powders of $45{\mu}m$ in averaged size were removed by using sodium hydroxide(NaOH) solution which is used for controlling pH. Nickel material is coated into the surface of oxide-removed Al powders by electroless-plating process. The microstructure of fabricated Ni/Al powders shows that nickel layers with a few hundreds nm were very homogeneously formed onto the surface of Al powders. The oxidation behavior of Ni/Al exihibit somewhat faster oxidation rate than that of pure Al with surface oxidation. Also, the higher exothermic reaction was observed from the Ni/Al powders. From the result of this, nickel coating is very promising method to obtain highly reactive and safe Al powders for energetic applications.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.284-290
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• 2020

Energetic thermoplastic elastomers (ETPEs) based on glycidyl azide polymer (GAP) and carboxylated GA copolymers [GAP-ETPE and poly(GA-carboxylate)-ETPEs] were synthesized using isophorone diisocyanate (IPDI), dibutyltin dilaurate (DBTDL), 1,4-butanediol (1,4-BD), and soft segment oligomers such as GAP and poly(GA-carboxylate). The synthesized GAP-ETPE and poly(GA-carboxylate)-ETPEs were characterized by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), calorimetry and sensitivity towards friction and impact. DSC and TGA results showed that the introduction of carboxylate group in GAP helped to have better thermal properties. Glass transition temperatures of poly(GA-carboxylate)-ETPEs decreased from -31 ℃ to -33 ℃ compared to that of GAP-ETPE (-29 ℃). The first thermal decomposition temperature in poly(GA_0.8-octanoate_0.2)-ETPE (242 ℃) increased in comparison to that of GAP-ETPE (227 ℃). Furthermore, from calorimetry data, poly(GA-carboxylate)-ETPEs exhibited negative formation enthalpies (-6.94 and -7.21 kJ/g) and higher heats of combustion (46713 and 46587 kJ/mol) compared to that of GAP-ETPE (42,262 kJ/mol). Overall, poly(GA-carboxylate)-ETPEs could be good candidates for a polymeric binder in solid propellant due to better energetic, mechanical and thermal properties in comparison to those of GAP-ETPE. Such properties are beneficial to application and processing of ETPE.