• Title/Summary/Keyword: High Explosives

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Experiment and Evaluation of Mist Diffusion from Water Tube for Blasting Dust Control in accordance with the Explosives Position (폭약 기폭위치에 따른 발파 분진제어용 워터튜브 주입수의 분무확산 실험 및 평가)

  • Yang, Hyung-Sik;Ko, Young-Hun;Kim, Jung-Gyu;Noh, You-Song;Park, Hoon;Cho, Sang-Ho
    • Tunnel and Underground Space
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    • v.25 no.1
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    • pp.46-55
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    • 2015
  • A water tube with detonating cord was devised to control the blast dust. Water diffusion experiments with different detonating cord positions were conducted during the series of experiments to optimize the design parameters of the tube. Images from high speed camera were analyzed to evaluate the results. AUTODYN program was adopted to simulate the diffusion process of water and compared with the images. Diffusion of water shows cross flow in case of external charge while the internal case shows radial flow. A bubble ring was formed during the numerical analysis of internal charge case as occurred in underwater blast. An additional bubble ring was formed by the reflection pressure from the ground. And the Weber number was determined as sufficient for spray atomization performance of the water tube.

Experimental and Numerical Study on the Dynamic Fracture Processes of PMMA Block by NRC Vapor Pressure Fracture Agent (NRC 증기압 암석 파쇄제에 의한 PMMA 블록의 동적 파괴 과정에 관한 실험 및 수치해석적 연구)

  • Gyeongjo Min
    • Journal of Korean Society of Disaster and Security
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    • v.16 no.1
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    • pp.91-103
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    • 2023
  • This study aims to investigate the dynamic fracture characteristics of rocks and rock-like materials subjected to the Nonex Rock Cracker (NRC), a vapor pressure crushing agent that produces vapor pressure by instantaneously vaporizing a liquid mixture crystallized through the thermite reaction. Furthermore, the study seeks to develop an analytical technique for predicting the fracture pattern. A dynamic fracture test was performed on a PMMA block, an artificial brittle material, using the NRC. High-speed cameras and dynamic pressure gauges were employed to capture the moment of vapor pressure generation and measure the vapor pressure-time history, respectively. The 2-dimensional Dynamic Fracture Process Analysis (2D DFPA) was used to simulate the fracture process caused by the vapor pressure, with the applied pressure determined based on the vapor pressure-time history. The proposed analytical method was used to examine various fracture patterns with respect to granite material and high-performance explosives.

Recrystallization of RDX High Energy Material Using N,N-Dimethylformamide Solvent and Supercritical $CO_2$ Antisolvent (디메틸포름아마이드 용매와 초임계 이산화탄소 역용매를 사용한 RDX 고에너지 물질의 재결정)

  • Kim, Chang-Ki;Lee, Byung-Chul;Lee, Youn-Woo;Kim, Hyoun-Soo
    • Clean Technology
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    • v.15 no.4
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    • pp.233-238
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    • 2009
  • Supercritical fluid processes have gained great attention as a new and environmentally-benign method of preparing the microparticles of energetic materials like explosives and propellants. In this work, RDX (cyclotrimethylenetrinitramine) was selected as a target explosive. The microparticle formation of RDX using supercritical anti-solvent (SAS) recrystallization process was performed and the effect of operating variables on the size and morphology of prepared particles was observed. N,N-Dimethylformamide was used as organic solvent for dissolving the RDX. The size of the RDX particles decreased remarkably up to less than $10\;{\mu}m$ by SAS recrystallization. In the range of operating conditions of the SAS process studied in this work, the finest RDX particles were obtained at 313.15K, 150 bar, and 15wt% RDX concentration in feed solution.

Method for evaluating the safety performance and protection ability of the mobile steel protective wall during the high-explosive ammunition test (고폭탄 탄약시험 간 이동형 강재 방호벽의 안전성능 판단 및 유효 방호력 평가 방법)

  • Jeon, In-Beom
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.6
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    • pp.573-582
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    • 2021
  • In this study, a series of processes for evaluating the effective protection against barriers that should be equipped in institutions that perform reliability tests on high-risk ammunition, such as high-explosive ammunition, were introduced. The impact that high-explosive bombs can have on personnel includes damage to the eardrum and lungs caused by explosion overpressure and penetrating wounds that can be received by fragments generated simultaneously with the explosion. Therefore, a high-explosive with COMP B explosives as its contents were set up, and an explosion protection theory investigation to calculate the degree of damage, numerical calculations and simulations were performed to verify the protection power. A numerical calculation revealed the maximum explosion overpressure on the protective wall when the high-explosive exploded and the penetration force of the fragment against a 50 mm-thick protective wall to be 77.74 kPa and 41.34 mm, respectively. In the simulation verification using AUTODYN, the maximum explosion overpressures affecting the firewall and personnel were 56.68 kPa and 18.175 kPa, respectively, and the penetration of fragments was 35.56 mm. This figure is lower than the human damage limit, and it was judged that the protective power of the barrier would be effective.

Dynamical Study on the Blasting with One-Free-Face to Utilize AN-FO Explosives (초유폭약류(硝油爆藥類)를 활용(活用)한 단일자유면발파(單一自由面發破)의 역학적(力學的) 연구(硏究))

  • Huh, Ginn
    • Economic and Environmental Geology
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    • v.5 no.4
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    • pp.187-209
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    • 1972
  • Drilling position is one of the most important factors affecting on the blasting effects. There has been many reports on several blasting factors of burn-cut by Messrs. Brown and Cook, but in this study the author tried to compare drilling positions of burn-cut to pyramid-cut, and also to correlate burn-cut effects of drilling patterns, not being dealt by Prof. Ito in his theory, which emphasized on dynamical stress analysis between explosion and free face. According to former theories, there break out additional tensile stress reflected at the free face supplemented to primary compressive stress on the blasting with one-free-face. But with these experimented new drilling patterns of burn-cut, more free faces and nearer distance of each drilling holes make blasting effects greater than any other methods. To promote the above explosive effect rationary, it has to be considered two important categories under-mentioned. First, unloaded hole in the key holes should be drilled in wider diameter possibly so that it breaks out greater stress relief. Second, key holes possibly should have closer distances each other to result clean blasting. These two important factors derived from experiments with, theories of that the larger the dia of the unloaded hole, it can be allowed wider secondary free faces and closes distances of each holes make more developed stress relief, between loaded and unloaded holes. It was suggested that most ideal distance between holes is about 4 clearance in U. S. A., but the author, according to the experiments, it results that the less distance allow, the more effective blasting with increased broken rock volume and longer drifted length can be accomplished. Developed large hole burn-cut method aimed to increase drifting length technically under the above considerations, and progressive success resulted to achieve maximum 7 blasting cycles per day with 3.1m drifting length per cycle. This achievement originated high-speed-drifting works, and it was also proven that application of Metallic AN-FO on large hole burn-cut method overcomes resistance of one-free-face. AN-FO which was favored with low price and safety handling is the mixture of the fertilizer or industrial Ammonium-Nitrate and fuel oil, and it is also experienced that it shows insensible property before the initiation, but once it is initiated by the booster, it has equal explosive power of Ammonium Nitrate Explosives (ANE). There was many reports about AN-FO. On AN-FO mixing ratio, according to these experiments, prowdered AN-FO, 93.5 : 6.5 and prilled AN-FO 94 : 6, are the best ratios. Detonation, shock, and friction sensities are all more insensitive than any other explosives. Residual gas is not toxic, too. On initation and propagation of the detonation test, prilled AN-FO is more effective than powered AN-FO. AN-FO has the best explosion power at 7 days elapsed after it has mixed. While AN-FO was used at open pit in past years prior to other conditions, the author developed new improved explosives, Metallic AN-FO and Underwater explosive, based on the experiments of these fundmental characteristics by study on its usage utilizing AN-FO. Metallic AN-FO is the mixture of AN-FO and Al, Fe-Si powder, and Underwater explosive is made from usual explosive and AN-FO. The explanations about them are described in the other paper. In this study, it is confirmed that the blasting effects of utilizing AN-FO explosives are very good.

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Comparative analysis of detonation velocity in determining product composition for high energetic molecules using stoichiometric rules (화학 양론적 규칙으로 고에너지 물질의 폭발 생성물 조성 결정에 따른 폭발속도 비교분석)

  • Kim, Hyun Jeong;Lee, Byung Hun;Cho, Soo Gyeong;Lee, Sung Kwang
    • Analytical Science and Technology
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    • v.30 no.6
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    • pp.405-410
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    • 2017
  • High energetic materials (HEMs) have been used in fuels, civil engineering and architecture as well as military purposes such as explosives and propellants. The essential process for the development of new energetic compounds is to accurately calculate its detonation performances. The most typical equation for calculating the explosive performance is the Kamlet-Jacobs (K-J) equation. In the K-J equation, the parameter such as the number of moles of gaseous products at the explosion, the average molar mass of gas products, and the explosion heat greatly affect the explosion performance. These depend on the product composition for the detonation reaction. In this study, detonation products of 65 high energetic molecules (HEMs) were calculated from the various rules such as Kamlet-Jacobs, Kistiakowsky-Wilson, modified Kistiakowsky-Wilson, Springall-Roberts rules to calculate more accurate detonation velocity (Dv). In addition, they were applied to five kinds of detonation velocity equations proposed by K-J, Rothstein, Xiong, Stine and Keshavarz. The mean absolute error and root mean square error of HEMs were obtained from experimental and calculated velocity value for each method. The K-J and Xiong equation that is slightly complex showed a lower mean absolute error than the simple Rothstein and Keshavarz equation. When the mod-KW rule was applied to the Xiong equation, the detonation velocities were the most accurate. This study compared the various method of calculating the detonation velocity of HEMs to obtain accurate HEMs performance.

The Study on the Fragment Ejection Velocity and Spray Angle from a High Explosive Cylindrical Warhead (실린더형 HE 탄두 폭발 시 파편의 속도 및 발사각 추정방법 연구)

  • Hwang, Changsu;Park, Younghyun;Park, Seikwon;Jung, Daehan;Lee, Moonsik;Kang, Sunbu;Kim, Deuksu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.12
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    • pp.904-912
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    • 2019
  • We have studied the numerical analysis about the fragment ejection velocity and spray angle when the High Explosive warhead detonated at proximity distance at an aircraft. To study the physical quantities about the warhead components is very important to assessment the vulnerability of aircraft. Generally, the physical quantities about the components of a warhead such as the mass, length, diameter and charge to mass ratio are unknown. Therefore, it is required to estimate the physical quantities by using physical continuities of similar threats. The empirical formulas to understand the dependence among charge to mass ratio, length and diameter ratio were driven by using the physical parameters of similar threatening such as terrier, sparrow. As a result, we confirmed that the dead mass ratio was closed to 20% of warhead mass since the metal case of the proximity threat acts as a simple carrier. This implies that the effective length and diameter of High Explosive Compound is smaller than the length and diameter of warhead, and become a key to understand the large ejection gradient velocity and small spray angle of fragments within 6 degree.

Dye Removal by Phlebia tremellosa and Lignin Degrading Enzyme Transformants (아교버섯(Phlebia tremellosa)의 리그닌 분해효소 형질전환체를 이용한 염료의 탈색)

  • Kum, Hyun-Woo;Ryu, Sun-Hwa;Lee, Sung-Suk;Choi, Hyoung-T.
    • Korean Journal of Microbiology
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    • v.46 no.1
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    • pp.93-95
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    • 2010
  • White rot fungi which have lignin degrading enzymes show high degrading activity to diverse recalcitrant compounds such as polycyclic aromatic compounds, dyes, explosives and endocrine disrupting chemicals. We have examined decolorizing activity of dyes by Phlebia tremellosa and two transformants which had genetically transformed using laccase or manganese peroxidase (MnP) gene. In case of methyl green, wild type strain showed 50% decolorization while laccase transformant (TF2-1) and MnP transformant (T5) showed more than 90% decolorization on day 3. Remazol brilliant blue R(RBBR) was decolorized up to 85% by two transformants while the wild type showed 67% decolorization on day 3. Transformants TF2-1 and T5 both showed increased laccase and MnP activity respectively during the whole growing phase.

Process variables of gamma-type aluminum trihydride in wet chemical synthesis (감마형 삼수소 알루미늄 습식합성반응의 공정변수 연구)

  • Yang, Yo-Han;Kim, Woo-Ram;Gwon, Yoon-Ja;Park, Mi-Jeong;Kim, Jun-Hyung;Cho, Young-Min
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.1
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    • pp.214-222
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    • 2018
  • Alane(aluminum trihydride, $AlH_3$) is a candidate material involving high energetic capacity for solid propellant or explosives. In this study aluminum trihydride-etherate ($AlH_3{\cdot}(C_2H_5)_2O$) was synthesized through a wet process, and solid alane was extracted by controlled crystallization. Alane crystals were grown during the crystallization step with phase conversion of aluminum trihydride-etherate to alane using an anti-solvent. Stable crystal forms were found by a 2 hour crystallization process at $85^{\circ}C$. Finally the extracted solid aluminium trihydride consisted mainly of ${\gamma}-type$ with $50-100{\mu}m$ in size.

Synthesis and Crystallization of Hydrazinium Nitroformate(HNF) as Eco-friendly Oxidizer (친환경 산화제 HNF 합성 및 결정화 연구)

  • Kim, Jina;Kim, Min Jun;Min, Byoung Sun
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.4
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    • pp.69-76
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    • 2015
  • Recently, environmental sustainability of the transitional explosives and propellants is an issue of growing importance in energetic materials. For examples, ammonium perchlorate(AP) as an solid propellants oxidizer could create a poisonous gas and atmospheric pollutions, such as HCl. Among the several oxidizers, hydrazinium nitroformate(HNF) is an effective candidate substance for eco-friendly oxidizer, which has high density, pressure index, and less smog generating property during combustion for the Divert and Attitude Control System(DACS). This study was confirmed a synthesis through various conditions, was performed for the essential data of solubility the crystallization process. Also, crystallization process such as cooling, drowning-out and sonication were performed.