• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.75-85
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• 2016

A pyrotechnic system consisting of donor/acceptor pair separated by a gap relies on shock attenuation characteristics of the gap material and shock sensitivity of the donor and acceptor charges. Despite of its common use, numerical study of such pyrotechnic train configuration is seldom reported because proper modeling of the full process requires precise capturing of the shock wave attenuation in the gap prior to triggering a full detonation of high explosive and accurate description of the high strain rate dynamics of the explosively loaded inert confinements. We apply a Eulerian level-set based multimaterial hydrocode with reactive flow models for pentolite donor and heavily aluminized RDX as acceptor charge. The complex shock interaction, critical gap thickness, acoustic impedance, and go/no-go characteristics of the gap test are quantitatively investigated.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.46-55
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• 2016

The kinetic analysis of a heavily aluminized cyclotrimethylene-trinitramine(RDX) is conducted using differential scanning calorimetry(DSC), and the Friedman isoconversional method is applied to the DSC experimental data. The pre-exponential factor and activation energy are extracted as a function of the product mass fraction. The extracted kinetic scheme does not assume multiple chemical steps to describe the complex response of energetic materials; instead, a set of multiple Arrhenius factors is constructed based on the local progress of the exothermic reaction. The resulting reaction kinetic scheme is applied to two thermal decomposition tests for validating the reactive flow response of a heavily aluminized RDX. The results support applicability of the present model to practical thermal explosion systems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.433-439
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• 2017

This research investigates the manufacturing process and characteristics analysis of $BKNO_3$ (Boron Potassium Nitrate) as pyrotechnic are commonly found in the aerospace, defense, and automotive industries. A solid pyrotechnic mixture is composed of an oxidizing agent, fuel, and binder. Precipitation process was used to uniformly mix the raw material. Through the analysis of the material characteristics and thermal response is designed optimum ratio by NASA CEA program. It was compared by performing the evaluation of these size/shape/sensitivity/calorimetry characteristics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.172-178
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• 2017

Thermal property is one of the important characteristic in the field of energetic materials. As the energy material is released during decomposition, DSC(Differential Scanning Calorimetry) is frequently used for the thermal analysis. In case of the dynamic DSC measurements, thermal dynamic change like melting is prevented from the thermal property measurements. And due to the predicting kg scale, the conditions of the heat exchange with the environment significantly is changed. In this study, As the method to resolve the problem, we predict the thermal aging property using the AKTS thermokinetic program from DSC measurements which performed isothermal method. Predicting the thermal aging properties from ARC(Accelerating Rate Calorimetry) measurement, we compare two results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.307-313
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• 2009

In general, pyroshock is generated from the actuation of separation devices for several stage, fairing, and satellite separation in the flight of a launch vehicle. During these events, transient vibration phenomenon called pyroshock, which shows large acceleration in the high frequency range, occurs and it can result in the malfunction of electronic components which is equipped inside the launch vehicle or satellite. In this paper, mesh washer isolators made out of SMA were introduced for the isolation of pyroshock. One type of isolator primarily used pseudoelastic characteristics of SMA and the other type of isolator used shape memory effect of SMA. For the study of basic load-displacement relationship of each SMA isolator, compressive loading tests were performed and the results showed the capability of the isolator itself. Pyroshock isolation tests were followed and verified the outstanding isolation performance of isolator. In addition, random vibration tests were also performed and checked the dynamic characteristics of each SMA isolator.

• Journal of the Korean Institute of Oriental Medical Informatics
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• v.13 no.1
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• pp.39-46
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• 2007

종고대도현재하단전재건신양생방면점착흔중요위치. 의가(醫家), 도가(道家), 불가등위료보지건강타문주료흔다노력화각식적연구. 하단전시태아재모친복중생활적지방(下丹田是胎兒在母親腹中生活的地方), 시정자재부친체내생장적중요부위시생명성장적지방(是精子在父親體內生長的重要部位是生命成長的地方), 위료보유지건강적영혼화육체취요단련단전보지단전기중최보편적방법취시단전호흡화수기(爲了保維持健康的靈魂和肉體就要鍛鍊丹田保持丹田其中最普遍的方法就是丹田呼吸和手技)(침구(鍼灸), 약(藥), 안마(按摩)), 본고취시통과수기유지건강적단전소주적고찰(本告就是通過手技維持健康的丹田所做的考察). 한의학설(韓醫學說);(종동양사상주기초(從東洋思想做基礎))치인체질병유음양설(治人體疾病有陰陽說), 오행설등동양문화적근원음양설시포괄인간자연계적세계만물(五行說等東洋文化的根源陰陽說是包括人間自然界的世界萬物), 음화양적상대성(陰和陽的相對性), 상보성(相補性), 상련성등(相連性等) 원리주적관찰(原理做的觀察), 오행설시목(五行說是木), 화(火), 토(土), 금(金), 수자연계적삼라만상오류군적상생(水自然界的森羅萬象五類群的相生), 상극(相剋), 상화사득만물질서조율(相和使得萬物秩序調律), 인체시삼라만상(人體是森羅萬象), 우주중적소우주(宇宙中的小宇宙), 산화계곡(山和溪谷), 천화강해(川和江海), 동식물(動植物), 생활도구(生活道具), 건축물(建築物), 천체화무의등조성료인체구조자연화생명적조화중한의학시용침술화약재치료료인적질병(天體和巫醫等組成了人體構造自然和生命的造化中韓醫學是用鍼術和藥材治療了人的疾病). 저양조화유지료신체건강, 여과파배료저종조화상호보충적관계취회출현이상, 취회질인병기질병(就會疾引病起疾病), 소이위료유지신체적조화취요호호적이해신체적구성(所以爲了維持身體的調和就要好好的理解身體的構成), 관리호신체적각부분(管理好身體的各部分). 저시논문규명적취시신체내양생최중요적지방시단전, 하단전적구조이해지후취회명백유지신체조화적경혈적관계(下丹田的構造理解之後就會明白維持身體調和的經穴的關係).

• Journal of the Korea Society for Simulation
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• v.28 no.3
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• pp.11-23
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• 2019

An AddSIM(Adaptive distributed and parallel Simulation environment for Interoperable and reusable Models) is developed to construct a composite environment that can be used in the overall stage from military demand analysis to test and evaluation. In addition, a base system model(BSM), which is a component model of the weapon system with standardized hierarchies, has been developed. This paper describes the critical design of BSM for the guided weapon system that can be operated in AddSIM. The guided weapon system BSM is designed for reusability and interoperability, and to have the same interface for assembly, even if the subcomponents have different resolution. Then, each subcomponent is defined and implemented according to the component resolution classification scheme. Finally, Combinations of subcomponents have been used to construct the guided weapon system of various resolution and the performance is compared and analyzed through simulation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.293-296
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• 2008

Most of the guided weapons have been kept and transferred at the launching tube and fired in case of necessity in these day. Launching tube is a kind of case to protect the guided weapons from external environments and conducted as a guide when they are fired. When we attached the guided weapons to launching tube we usually has used explosive bolt. Explosive bolts have been used explosives when they had to be separated. But when they are separated there are some bad effects; a flame, fragments and pyro-shock. Because of these bad effects there are many restriction to use bolt as joining devices to precision guided weapons. To solve these problems, it has been invented ball type bolt. The present work was represented quantitively the margin of separation safty and separation mechanism in ball type bolt to analyse the dynamic separation test. Unlike explosive bolt, ball type bolt is separated without a flame, fragments and pyro-shock. And it also has a good mechanical properties as much as those of explosive bolt.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.1-11
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• 2014

Sympathetic detonation (SD) of high explosives occurs when a detonating donor initiates neighboring acceptors. The present study focuses on the hydrodynamic simulation of one-on-one sympathetic detonation of 155 mm charge filled with PBXN-109. Both unbuffered and buffered SD configurations are performed while changing the distance between each charge, in order to investigate the detonation sensitivity to a donor initiation. The cause of a SD is by a shock impact for the unbuffered case at a close range, while at a distant range, blast fragment penetration is the primary cause. The buffers can reduce the incident sensitivity to a SD by reducing the strengths of shock wave and impinging fragments.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.66-73
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• 2018

A computational fluid dynamics simulation of pyrotechnic material combustion inside a cylindrical closed vessel was carried out using the Eulerian-Lagrangian method. The 5th order upwind WENO scheme and the improved delayed detached eddy turbulence model were implemented to capture shock waves. The flow structure was analyzed inside the cylindrical vessel with a pressure sensor installed at the side wall center. The analysis revealed that the pressure oscillated because of the shock wave vibration. Additionally, the simulation results with four different sensor tab depths implied that, inside the sensor tab, eddies were generated by the excessively large gap between the sensor diaphragm and the side wall. These eddies caused irregularity to the measured time-pressure curve, which is an undesirable characteristic.