• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.273-276
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• 2014

The development of a vehicle-mounted radar to detect the location of enemy artillery is mainly mounted during operation to the mobility of the equipment and efficiency of utilization range. It is equipped with an electronic device responsible for the operation of the radar system. Electronic equipments is performed functionality imparted without an error-specific in spite of disturbances such as vibration / shock caused by vehicle movement. Therefore, vibration / shock resistance is held to prevent damaging from vibration / shock generated from the outside environment during operation. In addition, a standardized and specified cabinet structure equipped with electronic equipment is placed in shelter to ensure additional safety for vibration / shock. In this study, it is evaluated by analytical method with vibration / shock resistance of the cabinet structures for ensuring structural safety factor is applied to the aluminum. It is verified the reliability of the structure and structural dynamics to verify by calculated natural frequencies adding the weight of the cabinet structure and the structural displacement and stress results confirmed with vibration / shock caused by the vehicle movement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.975-977
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• 2014

Recently, As portability of storage device has been increased, it is important to analyze the precise anti-shock analysis. For non-operational shock analysis, the accuracy of non-operational shock simulation has been improved. However, because operational shock analysis includes nonlinear process, it is hard to get clear result from operational shock simulation. In this paper, by using Lagrange multiplier method, the FE model including ramp-disk contact of nonlinear process will be analyzed. Through this, we find ramp-disk contact affect the dynamic of slider. Additionally, for the more accurate analysis, we should include ramp-disk contact process at the FE model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.499-504
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• 2004

The purpose of this study is to investigate a investigating of a floor-impact isolation system using damping materials in apartment buildings. The stiffness elastic modulus(k) by puls impact forces were calculated loss factor by Hilbert transforms. It is absolved that natural frequency was moved floor shock-absorbing materials and the impact force was reduced by floor panel. The slab was constructed by damping materials. As towards a result, the system showed inverse A 45dB by heavy weight-impact noise and inverse A 52dB by light-impact noise. High frequencies impact-noise can be reduced by upgrading naturial frequency of vibration and noise in the system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.27-32
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• 2007

this paper the acoustic signature from a supersonic nozzle is measured and compared to the result of a program developed for a gas turbine noise prediction. In order to measure the jet Mach Number, the pressure and temperature at the settling chamber was measured along with pressures from a pitot-tube placed near the exit. The results are also compared to the ones obtained with a shadow graph technique. Jet noise produced by an imperfectly expanded jet contains shock associated noise, which consist of broadband noise and screech tone noise. For subsonic condition, the directivity is dominant to the downstream direction due to turbulence mixing noise. For supersonic conditions, however, the directivity is dominant toward upstream direction due to shock associated noise. The comparison with a jet exhaust noise prediction code shows good agreement at supersonic conditions but needs to be improved at subsonic speeds.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.67-71
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• 2003

The propagation characteristics of the impulse wave discharged from the exit of a perforated pipe is investigated through a simple shock tube facility. The pressure histories and directivities of the impulse wave propagating outside from the exit of pipe with several different configurations are analyzed for the range of the incident weak shock wave Mach number between 1.02 and 1.2. In the shock tube experiments, the impulse wave are visualized by a Schlieren optical system for the purpose of understanding its propagation characteristics. The experimental results show that for the near sound field the impulse noise strongly propagates toward to the pipe axis, but for the far sound field the impulse noise uniformly propagates toward to the omnidirections, indicating that the directivity pattern is almost same regardless of the pipe type. Especially, it is shown that the perforated pipe has a little performance to reduce the impulse noise only for the near sound field

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.103-106
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• 2005

This paper reviews the dynamic load phenomenon referred to as 'silo quaking', caused shock vibration and loud noise, during gravity discharge in coal silos. Quaking in tall silo is examined using experimental data obtained from a Coal Power Plant and several experimental and numerical investigations available in the published literature. In the experiment, the acceleration was measured at various height on the silo column and floor and by doing so, not only could the variation of the amplitude of the quaking be observed, but also the propagation of waves could clearly be seen. Through an overview of recent research on this subject, it is shown that the current silo quaking is produced by slip-stick friction between the internal wall of silo and the granular material, i.e. coal.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.213-216
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• 2005

Active control method is applied to a flexible beam excited by a shock impulse by focusing on reducing the residual vibrations after the shock input. It is assumed that the shock input can be measured and is always occurred on the same point of the beam. If the system is well identified and the corresponding inverse system is designed reliably, it has shown that a very simple feed-forward active control method may be applied to suppress the residual vibrations without using an error sensor and adaptive algorithm. Both numerical simulation and experimental result show a promising possibility of applying to a practical problem.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.250-253
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• 2005

This paper is investigates the separation shock of payload fairing. Separation test of subscale PLF using half separation device and half PLA is performed. Resulting shock loads at equipment bay and fairing joint are measured. Pyroshock estimation is performed using AUTOSEA Pyroshock Module. Input data to analysis model is obtained from the separation test results of subscale PLF. And model of AUTOSEA is updated comparing results between tests and analysis.. This enables us to validate the AUTOSEA model. Tuned model of subscale PLF and separation device is used to update full scale model, and the shock analysis result of full scale model is estimated in this paper. This paper also discusses the results regarding the difficulty of structural modeling and its numerical implementation in AutoSEA2 Software.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.809-812
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• 2005

This paper explains environmental tests of vessel-launched missiles, verifying if a fully assembled missile performs properly from disturbance on delivery by vehicles or naval vessels. We also have operated vibration tests by ground and naval transportation as well as shock tests by naval transportation before firing. The environmental tests have adopted Military Standard Specification and confirmed missile's reliability by performance tests, followed by missile's development. However, this significant testing which have meaning was dong by the missile's body and not with parts.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.546-550
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• 2008

Impulsive excitation on vehicles produces shock-type vibration on the seat, usually which has major frequencies and damping ratios dependent on the characteristics of the suspension, the tire, the seat cushion and so on. The response of single degree of freedom model to a half-sine force input was considered as simple shock-type vibration signal. The quasi-apparent-mass for fifteen subjects was obtained with the shock-type vibration generated on the rigid seat, so its nonlinearity was found over 6.3 Hz according to the difference of magnitude of the shocks.