• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.340-343
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• 2011

Explosive bolts are reliable and efficient mechanical fastening devices having the special feature of a built-in release. The disadvantage of explosive bolt lies in that it is based on the high explosive effect of a pyrotechnic charge. The aim of the present work is to propose a pyrotechnically releasable mechanical linking device for two mechanical elements that does not suffer from such drawbacks. The pyro-lock using the pressure cartridge has the release characteristic without fragmentation and minimum pyro-shock. The present work is focused on the design, the interpretation of structure, the separation mechanism, separation force, and the results of various tests.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.101-108
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• 2015

In this paper, we have proposed a separable nose cap and its opening device to protect a seeker's window from aerodynamic heating and to decrease the drag force on missile body. The nose cap should be promptly deployed to secure the view field of seeker when it is needed. This cap consists of two nose cap structures and separation devices such as pyro puller and pusher. The performance of pyro puller was fully verified through analyses and several kinds of operating tests. We can obtain a sufficient confidence level of the pyro puller through many operating tests under various environments.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1061-1063
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• 2002

In this paper, the characteristics of the pyro unit applied to rocket release device in KSR-Ill are analyzed by experimental results, which are the current and voltage waveforms of the battery used as energy source. The precision design approach of the rocket release device can be achieved since the behavior and the required energy of the pyro are identified through the results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.581-586
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• 2000

Explosively activated pyro-technic device is used to release exhausted rocket booster or payloads at prescribed times in the rocket's flight. It creates pyro-shock environment that rocket or payload components must survive. With the shock spectra acquired from flight data, laboratory test should be performed before flight to check whether all of component can sustain the shock environment. The pyro-shock environment simulation was created by the resonance fixture response to a projectile impact. Desired shock spectra is realized by adjusting the natural frequency of resonance plate and the velocity of impact hammer. This paper describes the development process of Pyro-shock testing machine, which is designed and tested by Korean engineers, to verify components of Korean Sounding Rocket(KSR-3) and the other Korean space vehicle. Both analytical and experimental techniques are introduced in this paper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.26-29
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• 2017

KARI has been conducting R&D for independent development of KSLV-II since 2010. Vehicle holding device is a device for vertically standing SLV on the launch pad of launch complex and fixing the lower part of vehicle in order to firmly fix vehicle so that SLV does not fall from an external load such as a wind load. When thrust generated after the 1st stage engine ignition of SLV must exceed the takeoff weight of vehicle, and holding device should be quickly released so that it does not interfere with takeoff of vehicle like other ground equipment at the beginning of the launch. Pyro-valve is one of the key components constituting VHD, and it should have high reliability and quick response characteristics with similar functional parts applied to launch vehicle separation device and satellite separation device. Through this paper, I intend to broaden the overall understanding of the development process of pyro-valve for VHD and KSLV-II.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.239-242
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• 2004

The fairing of the launch vehicles has a role of protecting the spacecraft from outer thermal, acoustical, and mechanical loads during flight. Among them, the thermal load is analyzed in the present study. The ascent thermal analyses include aerodynamic heating rate on every point of the fairing, heat transfer through the fairing and spacecraft, and the final temperature during ascent flight phase. A design code based on theoretical/experimental database is applied to calculate the aerodynamic heating rate, and a thermal math program, SINDA/Fluint, is considered for conductive heat transfer of the fairing. The results show that the present design satisfies the allowing temperature of the structure. Another important thermal problem, pyro explosive fairing separation device, is calculated because the pyro system is very sensitive to the temperature. The results also satisfies the pyro thermal condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.4
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• pp.321-326
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• 2010

The non-explosive release device using jack mechanism is designed and fabricated for the small satellite. As a triggering actuator for the release device, a piezo rotory motor with torque of more than $1.7kgf{\cdot}cm$ is employed to guarantee stable activation. For performance tests of separation device, we conducted release time test, preload test and shock test. The device was operated within 1.172sec and activated stably under load of 45kgf. Maximum shock was measured as 18G that is much less than the pyro-separation device produces. We confirmed the possibility as a satellite separation device through above presented tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.358-362
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• 2006

Pyro-shock generally refers to the severe mechanical transients caused by the detonation of an ordnance device on a structure. Such device on a structure, including linear explosive, and point explosive are widely used to accomplish in-flight separation of structural elements on aerospace vehicle. And they are a significant cause of launch vehicle failures. The launch vehicle being developed in Korea also uses the explosive for separation events. In this paper, the isolator equipped to small satellite launch vehicle made of PTFE(Teflon) is developed to reduce the separation shock. The test to measure dynamic stiffness of PTFE isolator is performed. This test enables us to find the frequency range of PTFE isolator. And,, pyre-shock test using explosive to evaluate the performance of PTFE isolator is executed. from this study, the isolator conformed to frequency range and load requirement is developed using PTFE instead of rubber.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.813-822
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• 2008

The present work has been developed the interpretation processor including analysis of the failure stress in pyrotechnically releasable mechanical linking device, which has the release characteristic without fragmentation and pyro-shock, using SoildWorks, COSMOS Works and ANSYS programs. The aim of the invention is to propose a pyrotechnically releasable mechanical linking device for two mechanical elements that does not suffer from such drawbacks. The pyrotechnically releasable mechanical linking device according to the invention is simple, compact and inexpensive in structure. It is simple to implement and permit the use of only a reduced quantity of pyrotechnic composition, such composition possibly being devoid of any primary explosive at all. The present work is only focused on the design of structure and the material characteristics. To analyze the fracture morphology resulted from tensile test in the different ball type bolts, the present work has been performed to estimate the failure stress of material and to make the same result from tensile test. The failure stress of SUS 630 in ductile material is approximately 1050 Mpa. The failure stress of SUS 420 in brittle material is about 1790 Mpa. Among the models used the ductile material, the model 6 is suitable a design of structure compared to that of other models. The use of this interpretation processor developed the present work could be extensively helped to estimate the failure stress of material having a complex geometry such as the ball type bolt