• Tunnel and Underground Space
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• v.15 no.4 s.57
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• pp.296-304
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• 2005

This study is to observe stray currents generated around the steel tower by domestic transmission network system and analysis stability of electric detonator. It is measured the stay current of each ten place at steel tower of 765 kV, 345 tV, 154 tV transmission line among domestic transmission network system. Stay currents measured a total of 40m at intervals of 4m toward a line direction and a line vertical direction centering around steel tower. Temperature of the surface, EC, water content also are measured. Although stay currents show the highest values, that is 12 percent of at 4m and less than 1 percent of 40m with Institute of Makers of Explosives(IME) regulations. It is shown correlation between stay currents and water content$\cdot$EC$\cdot$temperature of the surface. Stay currents measured at line direction and line vertical direction were little different and the shape of diminution was also shown a similar aspect.

• Explosives and Blasting
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• v.40 no.1
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• pp.29-38
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• 2022

Electronic detonators are now widely used in various construction sites and quarry mines. Including the sites where safety-thing is located nearby, Cases of using electronic detonators are increasing to maximize operational efficiency by improving blast fragmentation or reducing the cost of secondary blasting. This case study is about applying for electronic detonators on zone 00 construction site, which is the part of urban area metropolitan express rail A line project. Although the project was initially planned to utilize non-electric detonators, Electronic detonators are considered as the solution not only for safe and fast excavation, but also to minimize civil complaint and the damage of safety-thing. By applying electronic detonators, we were able to satisfy environmental regulations standards and prevent nearby safety-thing from getting damaged.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.328-334
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• 2020

At the recent practice test of the Remote Controlled Munition system (for practice), nine out of 125 samples were generated. Although 7.2 % misfires occurred, the acceptance test met the defense standards. Minimizing the probability of broken fuses is essential to reducing the number of samples and improving the AQL according to the process quality. In addition, it is necessary to increase military training and ensure user safety. In the case of practical grenades, hit-type detonators are applied. Unlike the normal design, which takes a hit by strikers, a different design of a hit by pressure from a pressure generator was used. This study analyzed the detonator surface through computational fluid dynamics. The results showed that the probability of functional weakness and retraction increased with increasing slope of the detonator surface. To overcome this, design changes were made to improve the fuse crimping process and increase the detonator holder seat. A performance test with the same number of samples from the whole quantity was operated. The probability of broken fuses was 0 %. Therefore, the reliability and performance of the ammunition can be improved and is expected to contribute to the drawing and process design when developing similar ammunition.

• Explosives and Blasting
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• v.25 no.2
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• pp.11-21
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• 2007

The main structure of Gunsan steam power station was demolished by the toppling method using high explosives. Height of a main building is 58m and a total floor area is $292,000m^2$. It is Rahmen(rigid-frame) structure consisted of almost columns and beams and slabs exist only in one part of the building for the electricity generators equipments. To improve the efficiency of blasting work, it is separated into 4 sectors. Blasting floors were 1, 2, 3, & 4 stories from first sector to third sector, while 1, 2, 5, & 7 of fourth sector were blasted because it had not slabs. About 102.675 kg of the MegaMITE were used with 225 electric detonator and 638 non-electric detonators to check detonator connection and confidence of detonation. The blasting noise and vibration were monitored to evaluate the environment effect and the damage of the nearby structures.

• Explosives and Blasting
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• v.39 no.2
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• pp.15-26
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• 2021

Domestic electronic detonators are used widely in many quarry and construction sites since its launch at 2013. In the case of SOC projects conducted in the city, most of them are designed in high-depth to reduce complaints. The high-depth excavation needs a long construction period and huge cost for building shaft and ventilation hole. Mechanical excavation method is applied when safety things are located nearby the site. Solidity of rock and machine's performance affect on the method's efficiency. So as the efficiency is getting lower, the construction period is extended, and the cost is increases as well. This case study is about changing the machine excavation method to the blasting method which is electronic detonator applied at the shaft construction site in the city. This is an example of using electronic detonators on the construction site in reducing blast-noise and vibration while meeting environmental regulatory standards.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.2 s.21
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• pp.58-66
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• 2005

This paper presents miniaturized setback generators based on the conversion of mechanical energy into electrical energy for military applications, especially power supply for electronic fuzes. In order to minimize the volume of setback generators, a ring-shaped magnet enclosing a coil assembly is adopted. A mechanical safety system, shear plate, is used as a release mechanism of the setback generators to prevent the generators from operating accidentally. The setback generators are intended not to ignite an electrical detonator but to charge a capacitor which is capable of driving electronic circuit of fuze. We design the setback generators using the simulation results of an electromagnetic analysis tool, $Maxwell^{(R)}$ 2D. In experimental study, we perform safety tests of the shear plate and firing tests of the fabricated setback generators. The present setback generators show that the voltage of 14.2V is charged at the capacitor of $30{\mu}F$ within the charging time of 0.68msec and the critical acceleration for safety is 5,000G, thus verifying that the setback generators with a ring-shaped permanent magnet can be applicable to the power supply of small-caliber electronic fuze.

• Explosives and Blasting
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• v.38 no.2
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• pp.22-35
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• 2020

Recently, electronic detonators have been widely used in various sites. Electronic detonators are often used for the purpose of reducing the noise and vibration produced by blasting. In addition, electronic detonators are used for precision blasting at sites where mechanical excavation techniques are applied due to proximity of safety things or where blasting by conventional detonators are not possible. Various technologies are being attempted at the blasting site to increase constructivity and lower production costs by using electronic detonators. In this paper, we would like to introduce a construction case that use of electronic detonators in the situation of safety things being adjacent increases the efficiency of construction while meeting the ground vibration criteria of Ministry of Land, Infrastructure, and Transport. The blasting was carried out at domestic and overseas shaft using HiTRONIC II™, produced by Hanwha. Generally the shaft blasting is performed by dividing the blasting surface because of the noise and vibration caused by the blasting. but, in the case introduced in this paper, the blasting was carried out once without dividing the blasting surface, thus the construction period could be shortened.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.20-26
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• 2019

In this paper, we propose measurement based numerical resistivity model for low energy exploding foil initiator (LEEFI) of electronic safety and arming device(ESAD). A resistivity model describes a behavior of variable resistance in LEEFI by firing current. The previous resistivity model was based on high energy detonator applications as explosive bridge wire and exploding foil initiator. Therefore, to estimate the voltage, current, and burst time of LEEFI, a resistivity model suitable for LEEFI is needed. For the modeling of resistivity of LEEFI, we propose a specific action based equation which represents a behavior of LEEFI when firing current is applied. To verify the proposed model, we analyze a firing current transmission path to obtain parasitic impedance. We experimentally verify that the proposed resistivity model offers precise estimation for the behavior of variable resistance in LEEFI.

• Explosives and Blasting
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• v.37 no.2
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• pp.22-30
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• 2019

On sites where explosives are used, the effects of noise and vibration produced by the blast wave are subject to a number of operational restrictions. Recently, the number of civil complaints has increased and the standard of environmental regulations on secure goods has been greatly tighten. Therefore, work is generally carried out by machine excavation in case of close proximity of safety thing. Machine excavation methods have the advantage as reducing noise and vibration compared to blasting methods, but depending on the conditions of rock intended to be excavated, they are sometimes less constructive than planned. In general, the closer a rock type is to hard rock, the less constructible it becomes. In this paper, we are going to explain the construction of a construction section with a close proximity to a safety thing using electronic detonators. While the project site was designed with a machine excavation methods due to the close(9.9m) proximity of safety thing(the railroad), construction using electronic detonators was reviewed as an alternative method for improving rate of advance time and construction efficiency when expose to hard rock. Through blasting using electronic detonators, construction and economic efficiency were maximized while minimizing impact on surrounding safety things. Because $HiTRONIC^{TM}$, which is produced by Hanwha, has innovative stability and high explosion reliability, it is able to explode with high-precision accuracy. Electronic detonators are widely used in construction sites of railway or highway, other urban burrowing areas and large limestone mines.

• Explosives and Blasting
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• v.36 no.4
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• pp.48-61
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• 2018

This case study is concerned with the project of the explosive demolition for the KOGAS office building located in Bundang district in Seongnam city. Since the office building was a kind of long-span beam structures, a mechanical demolition method using jacking support systems was considered in the beginning of the project. With consideration of the excessive reinforcement cost, uncertainty of safety, and prolonged construction period, however, the original plan was later changed to use an explosive demolition method. For the purpose of protecting nearby buildings and facilities during the collapse process, the explosive initiation sequence was elaborately designed to bring down the building structure towards its front left corner. A total of over 550 electronic detonators (Unitronic 600) was used to sequentially initiate the explosives installed at appropriate columns in the first, second, and fifth floors. To diminish dust production, water bags of small and large sizes were respectively installed at each column and on the floors to be blasted. As such, every effort was exercised to mitigate overall noise, dust, and shock vibrations that could be generated during the explosive demolition process for the office building.