• Explosives and Blasting
• /
• v.30 no.1
• /
• pp.29-36
• /
• 2012

In this study, the influence of priming location inside a blast hole on the ground vibration has been studied. In most of the previous studies dealing with the ground vibration, the effect of priming location in a blast hole was usually considered in a limited way. Thus, it seems that the results of the studies can be applicable only to the relevant sites. Considering the fact that the mechanism of ground vibration caused by blasting is quite complex, the priming location can have a considerable effect on the ground vibration in certain situations and be an important parameter in a blasting design. To identify the characteristics of the wave propagation according to priming locations, total 72 test blasts were carried out with different spacing, burden, drilling length, and charge, and prediction equations were derived. The characteristics of ground vibration, which was changed according to the priming location, was analyzed by using the nomogram of peak particle velocity (PPV) record. Attenuation relations, which were also dependent on the priming location, were analyzed. In this case, four different amounts of charge, that is, 0.5, 1.6, 5, and 15 kg, were used for the test. This criterion of charge amount is specified in the "Blasting design and construction guidelines to road construction" by the Ministry of Land, Transport and Maritime Affairs of Korea.

• Explosives and Blasting
• /
• v.22 no.3
• /
• pp.1-12
• /
• 2004

In bench blasting, rock fragmentation is one of the most important factors determining productivity. Rock fragmentation could be affected by various conditions and these were hewn that rock joint conditions and in-situ block sizes were the biggest effect on it. This research is focused on what or how to influence on rock fragmentation according to relation between blasting conditions and the in-situ rock conditions such as rock joint conditions and in-situ block size. Field measurements were carried out in 3 open pit limestone mines, where in-situ rock conditions and blasting conditions were fully investigated. The results show that the parameters interact with blasting conditions complicatedly and especially in-situ block size has bigger effects. Dip direction of major joint set also can affect on fragmentation. Mean fragment size become smallest when dip direction of major joint set is about $30^{\circ}$ with the bench direction. The reason is considered to be come from difference of propagation paths of elastic wave.

• Explosives and Blasting
• /
• v.38 no.4
• /
• pp.1-15
• /
• 2020

With the increase of the utilization of underground space in Korea, explosion accidents at the underground facilities such as gas pipes have occurred frequently. In urban area with high population density, individual explosion accidents are likely to spread into large complex accidents. It is necessary to investigate the effect of explosion on the stability of underground structures in urban area. In this study, a sensitivity analysis was carried out to investigate the possible influence of nearby explosion on the stability of underground structure with 8 parameters including explosion conditions and rock properties. From the sensitivity analysis using AUTODYN, the main and interaction effects of each parameters could be determined. From the analysis, it was found that the distance between explosion point and tunnel, charge weight, and Young's modulus are the most important parameters on the stress components around a tunnel.

• Explosives and Blasting
• /
• v.40 no.2
• /
• pp.1-14
• /
• 2022

Numerical simulation is the most widely used methods for evaluating blasting performance. This study, conducted the numerical analysis of shock chamber model to evaluate the pressure confine effect of the stemming material and plug device. The stemming effect was compared and evaluated with that of the STF-based stemming material currently under development and sand, which is a commonly used blast stemming material. Furthermore, to verify of enhancement the confine effect inside blast hole pressure, three types of stemming plugs were adopted for the numerical analysis. The numerical simulation results revealed that the STF-based stemming materials were superior to the general stemming material. Also, It is evaluated that the STF-based stemming and Plug system can not only prevent detonation gas from overflowing the borehole prematurely, but also prolong the action time and scope of detonation gas in the borehole effective.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1999.04a
• /
• pp.21-21
• /
• 1999

예기치 않은 외부의 자극으로 인한 유도무기의 사고에 의해 인명 및 무기체계의 피해를 최소화하기 위하여 유도무기 둔감화 연구가 미국과 NATO를 중심으로 80년대 초반부터 활발히 수행되어 오고 있다. IM(insensitive munitions)은 예기치 않은 외부 자극에 노출되었을 때 성능과 작동요구조건을 충분히 만족시키면서 격렬한 반응을 최소화하는 무기로 정의된다. 1995년도까지 미 해군에서 사용하는 모든 전술 유도무기를 MIL-STD-2105B의 요구 조건에 부합하도록 둔감화 하기 위하여 1984년 미 해군에서 IM 프로그램이 만들어졌고, 1991년에 NATO의 NIMIC(NATO Insensitive Munitions Information Center)이 만들어져서 현재까지 둔감화약, 둔감 추진제, 복합재연소관 및 완화장치 등에 연구가 활발히 이루어지고 있다.

• Korean Chemical Engineering Research
• /
• v.52 no.6
• /
• pp.706-712
• /
• 2014

Explosives are reactive material that contain a great amount of high potential energy. They produce detonation if released suddenly, accompanied by the production of strong light, high heat, great noise and high pressure. Damage at surrounding detonation point is affected by high pressure and blast wave for explosives detonation. Consequently, analysis of pressure and blast wave is very important. This study focuses on the analysis of maximum overpressure and blast wave of explosives for safety assurance. First of all, four cases of the amount of HMX were selected. Secondly, maximum pressure and blast wave were calculated through detonation simulation along with a set of TNT and HMX quantities. The peripheral effect of detonation point was analyzed by calculating overpressure and absolute velocity and considering detonation occurred in the center of geometry by HMX. Also, maximum overpressure and blast wave of HMX were compared to equivalent amount of TNT, which was taken as a base case and verified through theoretical HMX graph. This study contributes to the base case for overpressure and blast wave of complex gunpowder containing HMX.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.23 no.5
• /
• pp.523-531
• /
• 2020

Extraction and anti-solvent crystallization were proposed to recover octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) from pressed polymer bonded explosives(PBXs). DXC-57 and DXC-59, whose polymeric binders are Estane and HyTemp with dioctyl adipate plasticizer, respectively, were used as pressed PBX models. Estane of DXC-57 was removed by washing with tetrahydrofuran prior to extraction, which enabled the crystallization of HMX at a low degree of supersaturation, sufficient to obtain β-form HMX. Using dimethyl sulfoxide and ethanol as the extraction solvent and the anti-solvent for crystallization, respectively, HyTemp and dioctyl adipate in DXC-59 were separated from HMX. The purity of recovered β-form HMX was higher than 99 %.

• Polymer(Korea)
• /
• v.38 no.4
• /
• pp.417-424
• /
• 2014

Reactivity and rheological behavior of highly concentrated polymer bonded explosives (PBX) simulant was studied. As a binder, thermosetting hydroxyl terminated polybutadiene (HTPB) was used. By using bimodal $CaCO_3$ (size ratio 10:1) and sugar particles (size ratio 25:1) as fillers, maximum 75 v% filling was possible during melt mixing. The relative viscosities of bimodal suspension were much lower than those of unimodal one and showed minimum values at 0.25 of fine particle fraction. In curing experiment, as curing temperature increased, the time of initiation and completeness of curing reaction became shortened, the torque kept low, and the change of internal temperature decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.172-178
• /
• 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 Korean Society on Water Environment
• /
• v.24 no.5
• /
• pp.523-532
• /
• 2008

A phase II site investigation and feasibility study was conducted at a military mortar shooting range near the demilitarized zone (Kyunggi, South Korea) to assess the extent of contaminants migration to the nearby Imjin river in which a flood control dam is under construction. The results showed that silty-clay soils around target areas were co-contaminated with heavy metals (Cd, Cu, and Pb) and explosives (HMX, RDX, and TNT). The total amount of contaminant was estimated to be 497.1 kg-RDX, 20.6 kg-HMX, 1.4 kg-TNT, 35.2 kg-Cd, 4,331 kg-Cu, and 5,115 kg-Pb, respectively. Both heavy metals and explosives were almost equally distributed on each soil particle size fraction. Neither subsurface soil samples nor ground water samples showed signs of contamination above the environmental criteria. The major migration route of contaminants was soil particles in surface run-off during rain at which a mass discharge rate of 30.0 mg-RDX/hour was observed.