• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.98-104
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• 2009

A solid kick motor is used for propulsion system of KSLV-I 2nd stage. During combustion of the kick motor, vibration and shock could be generated. And it could be transferred to the vehicle equipment bay through the kick motor body. If vibration and shock transferred to the vehicle equipment bay are considerable, electrical equipments could be disordered. Therefore we need to verify influence of vibration and shock caused by combustion of the kick motor. In this research, we measured vibration of the kick motor on the ground firing test. Based on this measurement data, we analyzed random vibration and shock response spectrum.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.214-217
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• 2005

To improve the safety of facilities and human beings when the ground fault occurs, public power utility prescribes the reasonable ground resistances, measures and controls the ground resistance of all the ground electrodes biennially. Concerning the safety of human, there are two safety criteria widely accepted, i.e. the IEEE Std 80-2000 and the IEC 479-1:1994. The IEEE Std 80-2000 is based on a simplified electric shock model usually translated into permissible touch and step voltages. The IEC 479-1:1994 is less specific than IEEE Std 80-2000 for analysis purpose. The IEC 479-1:1994 provides values of permissible body current against electric shock duration. This paper provides a technical study of these two standards to analyze the safety of human beings of ground electrodes developed recently for distribution power system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.114-122
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• 2002

The integration of the landing gear system is a complex relationship between the many conflicting parameters of shock absorption, minimum stow area, complexity, weight and cost. Especially ground impact load and dynamic behaviors greatly influence design load of landing gear components as well as load carrying structural attachment. This study investigates ground impact load and dynamic behaviors of the T-50 landing gear system using ADAMS. Taking into account for various operational/environmental conditions, an analysis of shock absorbing characteristics at ground impact is performed with experience derived from a wide range of proprietary designs. Analytical results are presented for discussing the effects of aircraft horizontal and vertical speed, landing attitudes, shock absorbing efficiency. This analysis leads us to the conclusion that the proposed program is shown to be a better quantitative one that apply to a new development and troubleshooting of the landing gear system.

• Earthquakes and Structures
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• v.26 no.1
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• pp.17-30
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• 2024

Earthquakes can lead to substantial damage to buildings, with long-period ground motion being particularly destructive. The design of high-performance building structures has become a prominent focus of research. The double-story isolated structure is a novel type of isolated structure developed from base isolated structure. To delve deeper into the building performance of double-story isolated structures, the double-story isolated structure was constructed with the upper isolated layer located in different layers, alongside a base isolated structure for comparative analysis. Nonlinear elastoplastic analyses were conducted on these structures using different ground motion inputs, including ordinary ground motion, near-field impulsive ground motion, and far-field harmonic ground motion. The results demonstrate that the double-story isolated structure can extend the structural period further than the base isolated structure under three types of ground motions. The double-story isolated structure exhibits lower base shear, inter-story displacement, base isolated layer displacement, story shear, and maximum acceleration of the top layer, compared to the base isolated structure. In addition, the double-story isolated structure generates fewer plastic hinges in the frame, causes less damage to the core tube, and experiences smaller overturning moments, demonstrating excellent resistance to overturning and a shock-absorbing effect. As the upper isolated layer is positioned higher, the compressive stress on the isolated bearings of the upper isolated layer in the double-story isolated structure gradually decreases. Moreover, the compressive stress on the isolated bearings of the base isolated layer is lower compared to that of the base isolated structure. However, the shock-absorbing capacity of the double-story isolated structure is significantly increased when the upper isolated layer is located in the middle and lower section. Notably, in regions exposed to long-period ground motion, a double-story isolated structure can experience greater seismic response and reduced shock-absorbing capacity, which may be detrimental to the structure.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.8
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• pp.481-485
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• 2003

In electric railway system, potential of rail has been risen, for return-current flows through rail. The magnitude of rising voltage is different to railway feed system, ground admittance of rail and the load current. If rising voltage of rail is large, electric shock can be occurred to passengers and maintenance- worker, In this paper, we estimate the rising voltage of rail in high speed railway system and check the safety to human beings.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.81-84
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• 2001

In industrial field, especially the mobile generator is almost used as a islanding generator source for light, electric thrill, and compressor, and so on. However, because there still exists a lot of aged load, it causes the electric shock against person. In this paper authors introduce the proper method to reduce the electric shock in field discussing the scheme of ground connection.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.34-40
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• 2016

A satellite is exposed to various impact environment until orbit entry. It is particularly undergoing the biggest impact by pyro shock, which is generated when the launch vehicle stages are separated or the satellite is separated from the launch vehicle. In this paper, due to the fact that the pyro shock is prerequisite for performing the test and verification on the ground, we developed an air-gun type shock tester for NEXTSat-1 shock test at the KAIST SaTReC along with the development of program introduced by LabVIEW software. The program operated in shock tester is consist of data measurement and analysis with the convenient implementation of user interface and its easy modification of the code.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.581-589
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• 2019

Guided missiles assembled with the bolted joint are subjected to various shock loading conditions while flying in the air and operating on the ground or platform. Especially, It is important to analyze the effect of the shock load on the structure because it affects the structure for a short duration time while its acceleration magnitude is quite large. In this study, mechanical shock tests on the structure with the bolted joint have been carried out to measure the acceleration changes of the structure against external shock loads by electrical exciter. Variation of dynamic characteristics of a structure with fastening methods and fastening forces has been investigated through Shock Response Spectrum analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.68-74
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• 2011

The touch or step voltages which exist in the vicinity of a grounding electrode are closely related to the earth structure and resistivity and the ground current. The grounding design approach is required to determine the grounding electrode location where the hazardous voltages are minimized. In this paper, in order to propose a method of mitigating the electric shock hazards caused by the ground surface potential rise in the vicinity of a counterpoise, the hazards relevant to touch voltage were evaluated as a function of the soil resistivity ratio $\rho_2/\rho_1$ for several practical values of two-layer earth structures. The touch voltage and current on the ground surface just above the test electrode are calculated with CDEGS program. As a consequence, it was found that burying a grounding electrode in the soil with low resistivity is effective to reduce the electric shock hazards. In the case that the bottom layer soil where a counterpoise is buried has lower resistivity than the upper layer soil, when the upper layer soil resistivity is increased, the surface potential is slightly raised, but the current through the human body is reduced with increasing the upper layer soil resistivity because of the greater contact resistance between the earth surface and the feet. The electric shock hazard in the vicinity of grounding electrodes is closely related to soil structure and resistivity and are reduced with increasing the ration of the upper layer resistivity to the bottom layer resistivity in two-layer soil.

• Explosives and Blasting
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• v.9 no.3
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• pp.3-9
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• 1991

On Influence of ground Vibration occured when smoky-chimney is demolished. The Shock Energy by falling down of smoky-ehimney(60m height ) demolition spread mainly to the breaking reinforced concrete and to ground Vibration.