• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.84-90
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• 2017

Explosive bolt is coupled in a variety of guided weapons and space projectiles, to perform the separation function. Thus, the role of the explosive bolt in guided weapons systems is very important, as it can cause failure of the entire system in the case of mission failure. For this reason, the design life prediction for explosive bolt is highly and frequently required recently, but its accurate prediction method has not been presented. In order to apply the existing accelerated aging process, we should know the activation energy and the acceleration factor of the explosive bolt. Since the information required for accelerated aging is not presently secured, it is difficult to predict the design life of explosive. Thus, in the present study, we have evaluated the performance of actual explosive bolts in the condition of natural aging over 10 years in order to present a minimum design life.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.67-74
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• 2016

Explosive bolt is one of separation device that uses high explosive charge, and is separated by pressure formed by an explosion and the resulting shock waves. Explosive bolt having such a mechanism would have to be designed to minimize shock and debris formation generated during separation. In this study, separation tests were carried out with distance as variable for restraining the explosive bolt (Air Gap). Bolt release and its separating shape with variation of air gap is observed, and we used accelerometer to measure the shock wave transmitted through a bound object. In addition, separation behavior of explosive bolt is analyzed using ANSYS AUOTODYN program. By comparing the results of previously performed experiments and analysis, we could confirm the effects of air gap to the release behavior of explosive bolt, and decide optimum constraining environment for specific separation bolts.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.437-443
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• 2024

The purpose of radiological Dispersal Device(RDD) is to kill people by explosives and to cause radiation exposure by dispersing radioactive materials. And It is a form of explosive that combines radioactive materials such as Co-60 and Ir-192 with improvised explosives. In this study, we tested and evaluated whether it was possible to read the internal structure of an explosive using X-rays in a radioactive explosive situation. The improvised explosive device was manufactured using 2 lb of model TNT explosives, one practice detonator, one 9V battery, and a timer switch in a leather briefcase measuring 41×35×10 cm³. The radioactive material used was the Co-60 source used in the low-level gamma ray irradiation device operated at the Advanced Radiation Research Institute of the Korea Atomic Energy Research Institute. The radiation dose used was gamma ray energy of 1.17 MeV and 1.33 MeV from a Co-60 source of 2208 Ci. The dose rates are divided into 0.5, 1, 2, and 4 Gy/h, and the exposure time was divided into 1, 3, 5, and 10 minutes. Co-60 source was mixed with the manufactured explosive and X-ray image reading was performed. As a result of the experiment, the X-ray image appeared black in all conditions divided by dose rate and time, and it was impossible to confirm the internal structure of the explosive. This is because γ-rays emitted from radioactive explosives have higher energy and stronger penetrating power than X-rays, so it is believed that imaging using X-rays is limited By blackening the film. The results of this study are expected to be used as basic data for research and development of X-ray imaging that can read the internal structure of explosives in radioactive explosive situations.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.749-754
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• 2004

Up to now, non-explosive demining system adaptable to a mobile robot has been developed. This system has much smaller platform and consists of non-explosive mechanism. Brief experiment indoors showed thai developed demining system can remove landmines well. But, out of doors, some problems are detected i.e. Inclination of overall system causes a suspension of rake rotation. In this research, a study on performance improvement of developed non-explosive demining system is mainly discussed. To compensate the inclination of the system, mechanical sensor composed of shaft and spring is used. This sensor gives a signal to a leadscrew motor and controls a rotating direction. From an experiment, it is confirmed that the mechanical sensor as stated is a good solution of the inclination of the system.

• Explosives and Blasting
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• v.28 no.1
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• pp.55-62
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• 2010

Explosive welding was planed in a closed drift of a mine for its reuse. In this study, we analyzed the stabilization of roof and pillar which were expected to be affected by overpressure experienced during the continual explosive welding. Three equations, normal equation, CONWEP and DDESB, were used for the estimation of overpressure. The investigation shows that the continual use of the explosive welding in a drift may result in considerable damage on the drift.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.155-161
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• 2005

Up to now, a lot of unmanned demining systems have been developed. However, some inferiority surely exist by reason of their large platform and explosive mechanism. To settle this inferiority, non-explosive demining system adaptable to a mobile robot already has been developed. Brief experiment indoors showed that developed demining system can remove landmines well. But, out of doors, several problems are detected. In this research, a study on the performance improvement of developed non-explosive demining system is mainly discussed. To overcome downhill effect, mechanical sensor composed of shaft and spring is used. It is confirmed that clearance depth control using the mechanical sensor is a good solution for the inclination of the system.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.243-248
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• 2001

The present work is described the design factors and separation mechanism of ridge-cut explosive bolt in order to optimize the stage separation characteristics. Characteristics of test samples would differ depend on the detonating devices, the shape and size of bolt body, the amount of loading explosives, and the confinment conditions of bolt. Based on the results from these experimental factors, it appears to optimal condition of ridge-cut explosive that the amount of loading explosive seems to be near 110mg of RDX, the height of loading explosive is 3.5mm, the thickness of bolt is 3.9mm, and the degree of ridge is approximately $120^{\circ}$

• Journal of Welding and Joining
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• v.14 no.2
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• pp.65-70
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• 1996

Detonation velocity of domestic expolsives was measured using the Dautriche method. The variables employed in this study were the thickness of explosive and the amount of salt added in the ammonium nitrate(AN) explosive. As the results of this study, it was shown that the detonation velocity increases with an increase of explosive thickness but decreases with an increase of salt content. It was further demonstrated that the detonation velocity decreases rather rapidly when the salt content increases over 20 percent. In addition, the accuracy of Dautriche method was evaluated as a preliminary study and its result showed that this method is quite reliable with an experimental error of less than 10 pct.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.477-480
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• 2006

Normally, with all ensuring the fire resistance structure as a method of setting the required cover thickness to fire, the RC is significantly affected from the standpoint of its structural stability that the compressive strength and elastic modulus is reduced by fire. Especially, high strength concrete and lightweight aggregate concrete is occurred serious fire performance deterioration by explosive spalling. Thus, this study is concerned with explosive spalling of lightweight concrete using structural lightweight aggregate. From the experimental test result, lightweight aggregate concrete is happened explosive spalling. The decrease of cross section caused by explosive spalling made sharp increasing gradient of inner temperature.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.667-670
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• 2003

The purpose of this study is to present data for the reusing, reinforcement and estimation of safety of the RC structure damaged by fire, and for the prevention of explosive spalling by checking the character of explosive spalling according to kinds of fine aggregate, admixture and water-cement ratios. The materials used fine aggregates were sea sand, crushed sand and recycled sand, and the admixtures were fly ash and blast-furnace slag. Also the water-cement ratios was 55% and 30.5%. After those were heated respectively for 30 and 60 minutes in accordance with Standard Time-Temperature Curve. And then conditions of explosive spalling were divided into five grades, and characters of explosive spalling were investigated.