• Tunnel and Underground Space
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• v.20 no.4
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• pp.252-259
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• 2010

In urban tunnels, namely, in case there are residents in the near distance, we normally use non-vibration and ambient vibration which are not blasting methods because it’ impossible to meet the blasting vibration regulation with only normal explosives. However, non-vibration methods not only cause increase of excavating cost, but need much time than explosives. Generally, the lower velocity explosives with 2,000 m/s VOD have been applied to ambient vibration blasting in open cut area, but difficult in tunneling in its use. However, by charging the hole together with lower velocity explosives and normal explosives, we have got the result which shows 20~30% vibration decrease compared with using only normal explosives. Therefore, I’ like to suggest the blasting method which is able to do as ambient vibration using lower velocity explosives mixed with normal explosives in urban tunnel and the area which is adjacent to security facilities within the vibration regulation.

• Explosives and Blasting
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• v.14 no.4
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• pp.4-12
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• 1996

In '50, It was turnning point of tunneling technology that v-cut of single Face replaced by Burn cut.. Which was a standard Blasting formula. In '70, We faced Seoul Sub-Way construction by NATM. As it was damages to the Structure on the surface, finally we made empirical formula. For Granite $V=kw^{0.57}D^{1.75}$ For Grneiss $V=KW^{0.5}D^{1.75}$ For Concrete breaker $V=KW^{0.5}D^{1.75}$ (K=7) The magnitude of groun vibration can be reduced as using follow matters. First, by using explosive that have low dencity and low Velocity of detonation. Second adopting two stage deck charging, third, by using Milli Second electric Caps and Multi-Sequency blasting machine.

• Explosives and Blasting
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• v.24 no.2
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• pp.65-73
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• 2006

Blast vibrations produced by emulsion explosives, controlled explosives and no vibration Kinecker through test blasting have been analyzed. Test area is mainly composed of andesite of which uniaxial compressive strength is $1,260kg/cm^2$. The empirical scaling formula from a logarithmic plot of peak particle velocity versus scaled distance have been determined and particle velocities with scaled distance have been evaluated for each explosive type. Vibration level of no vibracon KINECKER is lower than one of the controlled vibration blasting by about 30.71% and also lowers than one of the blasting of medium by about 50.94%.

• Journal of the Korean Professional Engineers Association
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• v.21 no.4
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• pp.12-18
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• 1988

On the foundation work of Po-Ryong power plant #3 & #4. It was 30meters away from the running states of #1 & #2 plant site. In order to protect the #1 & #2 power plant facilities & factory structure. Allowable vibration was required below 0.07 gal. Therefore, it had to set up the anti-vibration trench to reduce the vibration reference and secondary. I applied the low gravity and low velocity explosives with M/S delay caps by cautious blasting pattern.

• Explosives and Blasting
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• v.16 no.4
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• pp.18-28
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• 1998

Effects of blasting vibrations on curing concrete have not been well studied. As a result, unreasonable and strong blasting vibration constraints have been placed on blasting when it occur in the vicinity of curing concrete. To study the effects of blasting on curing concrete blocks of $33.3{\times}27.7{\times}16.2cm$ were molded and placed on the quarry. Several sets of concrete blocks were subjected separately to peak vibrations of 0.25, 0.5, 1.0, 5.0 and 10cm/sec. The impulses of blasting vibrations were applied with thirty-minute intervals. Along with unvibrated concrete blocks, the vibrated concrete samples cored with 60.3mm in diameter were measured for elastic moduli, sonic velocity and uniaxial compressive strength. Test results can be summarized as follows; 1. The blasting vibrations between 6 and 8 hours after pour generally lowered on the uniaxial compressive strength of the concrete. 2. A low blasting vibration of 0.25cm/sec did not affect the uniaxial compressive strength. As the magnitude of the blasting vibration increases, compressive strength of concrete is decreased. 3. Physical properties of the P-wave velocity, Young’s modulus, and Poisson's ratio showed a weakly decreasing trend in the concrete blocks vibrated between 6 and 8 hours after pour.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.207-215
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• 2001

Plastic bonded explosive(PBX) is mainly composed of the nitramine-ploymer compositions. PBX is characterized by high velocity and pressure of detonation, low vulnerability and good thermal stability. Many important applications of PBX require the good adhesion between nitramine crystals and the binder. For PBXs as well as propellants, where good mechanical properties are of great importance, dewetting therefore must be prevented by strong adhesion between filler-binder. Adhesion depends on surface characteristics of filler and binder. In order to design for better adhesion, an understanding of the surface properties of explosive and binder is required. The surface free energies are calculated from contact angle values by the method of Kaelble. Critical surface tension of solids are calculated by Zisman plot. Critical surface tension is a useful parameter for characterizing the wettability of solid surface. In this study, HMX and 3 kinds of copolymers are selected, since they are widely used in many plastic bonded explosives. The technical objective of this investigation is to predict the interaction between filler and binder from their surface free energies.

• Explosives and Blasting
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• v.24 no.2
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• pp.23-31
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• 2006

Optimum additive which gets Possible detonation sensitivity and minimum stability has been selected among several additives. It is able to mitigate a chemical reaction without destroying a structure of emulsion. Kinecker has been developed by mixing both matrix and selected additive through a perfect formulation. The detonation pressure is reduced by 40.66%(47.27% by Nitro Dyne's program), and hole pressure by 33.25% and even VOD by 52.88% against currently used emulsion explosives.

• Advances in Computational Design
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• v.8 no.4
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• pp.309-325
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• 2023

An innovative inertial reactive armor is being developed through a multi-discipline project. Unlike the well-known explosive or non-explosive reactive armour that uses high-energy explosives or bulging effect, the proposed inertial reactive armour uses active disc elements that is set to rotate rapidly upon impact to effectively deflect and disrupt shaped charges and kinetic energy penetrators. The effectiveness of the proposed armour highly depends on the tangential velocity of the impact point on the rotating disc. However,for a single layer armour with an array of high-speed rotating discs, the tangential velocity is relatively low near the center of the disc and is not available between the gap of the discs. Therefore, it is necessary to configure the armor with double layers to increase the tangential velocity at the point of impact. This paper explores a multi-objective geometry design optimization for the double-layered armor using Nelder-Mead optimization algorithm and integration tools of the python programming language. The optimization objectives include maximizing both average tangential velocity and high tangential velocity areas and minimizing low tangential velocity area. The design parameters include the relative position (translation and rotation) of the disc element between two armor layers. The optimized design results in a significant increase of the average tangential velocity (38%), increase of the high tangential velocity area (71.3%), and decrease of the low tangential velocity area (86.2%) as comparing to the single layer armor.

• Explosives and Blasting
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• v.14 no.4
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• pp.13-19
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• 1996

Lately, the improtance of smooth blasting is increasing on every construction fields, suchas underground caves, tunnels, and roadconstruction, etc. The main purpose of smooth blasting is to prevent unnecessary cracks from the base rockwhich preserved permanently and is to gain the smooth fracture plane. So, in smooth blashing, explosives with low detonating velocity are generally used. But it is difficult to discuss general theory on the smooth blashing because the mechanical properties of pertienent rocks are difficult regionally. Accordingly basic reserches on the smooth blasting are demended. In this paper, the mechanisms of the smooth blasting on the rocks containing discontinuities were discussd. Firstly, the writer predicted the formation of fracture plane and unevenness using mathematical methodology, the next the model blast tests were conducted in order to simulate the crack propagation modes from the blast holes. Through the research, the following conclusions were obtained l)The blast test results were in reasonally good agreement with the theoretical prediction. 2)The degree of discontinuity has an influence on the fracture morphology.

• Geophysics and Geophysical Exploration
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• v.13 no.2
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• pp.153-158
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• 2010

To investigate the velocity structure in the central and southern parts of the Korean peninsula, a 299-km NW-SE seismic refraction profile KCRT-2008was obtained across major tectonic boundaries. Seismic waves were generated by detonating 250 ~ 1500 kg explosives at depths of 50 ~ 100 m in eight drill holes located at intervals of 21 ~ 113 km. The seismic signals were detected by 4.5 Hz geophones at a nominal interval of 500 m. The first-arrival times were inverted to derive a velocity tomogram. The raypaths indicate several mid-crust interfaces including those at approximate depths of 2 ~ 3, 11 ~ 13, and 20 km. The Moho discontinuity with refraction velocity of 7.7 to 8.1 km/s has a maximum depth of 34.5 km under the central portion of the peninsula. The Moho becomes shallower as the Yellow Sea and the East Sea are approached on the west and east coasts of the peninsula, respectively. The depth of the 7.6 km/s velocity contour varies from 31.3 km to 34.4 km. The velocity tomogram shows the existence of a 129 km wide low-velocity zone centered at 7.2 km depth under the Okchon fold belt and Gyeonggi massif and low-velocity(< 5.4 km/s) rocks in the Gyeongsang sedimentary basin with a maximum thickness of 2.6 km