• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5A
• /
• pp.557-564
• /
• 2009

In recent years, there have been numerous explosion-related accidents due to military and terrorist activities. Such incidents caused not only damages to structures but also human casualties, especially in urban areas. To protect structures and save human lives against explosion accidents, better understanding of the explosion effect on structures is needed. In an explosion, the blast overpressure is applied to concrete structures as an impulsive load of extremely short duration with very high pressure and heat. Generally, concrete is known to have a relatively high blast resistance compared to other construction materials. However, information and test results related to the blast experiment of internal and external have been limited due to military and national security reasons. Therefore, in this paper, to evaluate blast effect on reinforced have concrete structure and its protective performance, blast tests are carried out with $1.0m{\times}1.0m{\times}150mm$ reinforce concrete slab structure at the Agency for Defence Development. The standoff blast distance is 1.5 m and the preliminary tests consists with TNT 9 lbs and TNT 35 lbs and the main tests used ANFO 35 lbs. It is the first ever blast experiment for nonmilitary purposes domestically. In this paper, based on the basic experiment procedure and measurement details for acquiring structural behavior data, the blast experimental measurement system and procedure are established details. The procedure of blast experiments are based on the established measurement system which consists of sensor, signal conditioner, DAQ system, software. It can be used as basic research references for related research areas, which include protective design and effective behavior measurements of structure under blast loading.

• Explosives and Blasting
• /
• v.35 no.4
• /
• pp.19-26
• /
• 2017

The most widely used method for determining the blast effects of explosives is the Trauzl lead block test. This test is used to measure the explosive power (strength) of a substance by determining volume increase, which is produced by the detonation of a test explosive charged in the cavity of a lead block with defined quantity and size. In this paper, Trazul lead block test and AUTODYN numerical analysis were conducted to evaluate the coupling medium effect of blast hole. The effects of coupling materials can be expressed as the expansion of the cavity in a standard lead block through explosion of the explosives. The tests were conducted with emulsion explosives. The coupling mediums used as the filling material around a explosive charge were air, sand, water and gelatine. Results of test and numerical analysis showed that expansion of lead block were much more affected by water&gel than by sand and air. The water and gel showed similar results. As expected, the transmitted pressure and dynamic strain was higher in water and gelatine coupled blast hole than in air and sand.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.2
• /
• pp.102-114
• /
• 2004

The present work has been developed the interpretation processor including the behavior of material failure and the separation phenomena under transient dynamic loading (the operation of explosive bolt) using AUTODYN V4.3, SoildWork 2003 and TrueGrid V2.1 programs. It has been demonstrated that the interpretation in ridge-cut explosive bolt under dynamic loading condition should be necessary to the appropriate failure model and the basic stress of bolt failure is the principal stress. The use of this interpretation processor developing the present work could be extensively helped to design the shape and the amount of explosives in the explosive bolt having a complex geometry. It is also proved that the interpretation processor approach is an accurate and effective analysis technique to evaluate the separation mechanism in explosive bolts.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.8
• /
• pp.767-773
• /
• 2010

This paper describes development of a non-explosive separation device which can be equipped on small satellites. The spur geared micro DC motor, which has high reliability and advantage of price, is adopted as an actuator. The proposed separation device has resettability and it does not need extra jig to reload. In addition, the simple structure makes it easy to fabricate and assemble. To verify the performance of the proposed device, the response time tests, maximum preload tests and maximum shock level tests were performed. Also, through the vibration tests and thermal vacuum tests, feasibility of the proposed separation device was shown in launching and space environments. Therefore, we expect that the proposed separation device can replace the imported separation devices in near future.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.7
• /
• pp.565-572
• /
• 2021

In this study, a study on the performance and aging of explosive bolts stored for a long time among pyrotechnic mechanical devices(PMD) used as separation devices in the defense field is conducted. For this, explosive bolts that had been installed in the weapon system for about 10 years are secured. Performance and life extension test procedures are established based on the AIAA Standard and MIL-STD. Before performance evaluation, non-functional tests are performed to check whether external changes or failures occurred. Next, circuit inspection and X-ray tests are conducted to check the failure in internal circuits and structures. After that, performance test is carried out to confirm the operation of the samples that passed the non-functional test. Through this test, separation of bolt and separation time are measured, and some samples are tested after a high temperature storage test to confirm the remaining life and the possibility of extension. Finally, the remaining life and reliability are predicted based on the results of the test and the Arrhenius model to identify remaining shelf life and reliability depend on time.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.5
• /
• pp.457-463
• /
• 2009

This paper describes the development of non-explosive separation(NES) device which can be equipped on a small satellite. It comprises mechanism itself and spring-type shape memory alloy(SMA) actuator. In order to design SMA actuator properly, the necessary actuation force is measured. Based on that result, SMA actuator is designed and fabricated. Finally, SMA actuator and the proposed mechanism are integrated. In order to evaluate performance of the developed NES, we carried out a response time test, preload test and shock level test. In near future, we expect to replace the imported NES device with the developed device.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2012.04a
• /
• pp.113-116
• /
• 2012

플랜트란 산업 기계, 전기 통신 기계등 여러 가지를 생산하는 공장을 의미하고 있다. 해양플랜트는 바다위에 설치된 시설이라고 볼 수 있으며 주로 원유 및 가스를 채취하여 시중에서 사용할 수 있도록 정유공정까지 거치는 대규모 설비라고 할 수 있다. 따라서 가연성 물질을 생산, 적재함으로 화재 및 폭발의 위험성이 상존하며 화재가 발생하면 인화성 물질로 인한 대규모 화재와 폭발로 인하여 인명과 재산피해의 규모 또한 가름하기가 어렵다. 본 논문에서는 해양플랜트 화재시 화재와 폭발 두 가지 위험성 중 제트화재에 저항을 가지는 기자재를 평가할 수 있는 ISO 22899-1 시험방법과 설비에 대하여 설명하고자 한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2005.11a
• /
• pp.173-176
• /
• 2005

The present work has been studied the reliability improvement of inspection method for explosive bolt body. The standard value of impact test is made from impact test of explosive bolt body and a useful data is established to the correlation between the hardness and impact data of bolt body. The method is overcome an error obtained from conventional inspection by analysing the mechanical data from each inspection and can be improved to the reliability when mechanical property of explosive bolt body is inspected.

• Fire Science and Engineering
• /
• v.12 no.3
• /
• pp.3-9
• /
• 1998

We investigated the weight loss according to temperature using TGA in order to find the thermal hazard of brand-new activated-carbon and disused activated-carbon dusts, and the properties of dust explosion in variation of the specific surface area of their dust with the same particle size. Using hartman's dust explosion apparatus which estimate dust explosion by electric ignition after making dust disperse by compressed air, dust explosion experiments have been conducted by varying concentration and size of activated carbon dust. The explosion pressure of both activated carbon increased as the specipic surface area increased. The results indicated that brand-new activated-carbon of which specific surface area was larger three to four times than that of disused activated-carbon was much easier of dust explosion.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.6
• /
• pp.605-611
• /
• 2010

The geostationary satellite COMS is going to be launched in 2010, and, in the series of test, there are some high-pressure tests concerning the vessel tank filled with helium gas of hundreds atmospheric pressure. In this paper, authors evaluates risk associated with accidental rupture of the test system. Two possible scenarios are considered: 1) the 310-bar helium tank ruptures at the center of the acoustic chamber, and 2) the 116-bar reduced-pressure helium tank ruptures in the test room shielded by bullet-proof glasses. Using the theory of blast wave propagation and computational simulation, the dynamics of wave reflected in a confined space is investigated for highly complex unsteady flow physics.