• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1218-1226
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• 1994

The shock tube is a useful device for investigating shock phenomena, spray combustion, unsteady gas dynamics, etc. Therefore, it is necessary to analyze exactly the flow phenomena in shock tube. In this study, the mechanics of its reflected shock zone has been investigated by using of the one-dimensional gas dynamic theory in order to estimate the transition from initial reflection of shock wave region. Calulation for four kinds of reflected shock tube temperature (i.e. (a) 1388 K (b) 1276 K (c) 1168 K (d) 1073 K) corresponding to the experimental conditions have been carried out sumarized as follows. (1) The qualitative tendency is almost the same as in that conditions in region of reflected wave region. (2) High temperature period (reflected shock wave temperature) $T_{5}$, exists 0-2.65 ms. (3) Transition period from temperature of reflection shock wave is far longer than the calculated one. This principally attributed to the fact that the contact surface is accelerated, also, due to the release of energy by viscoity effect. This apparatus can advance the ignition process of a spray in a ideal condition that involved neither atomization nor turbulent mixing process, where, using a shock tube, a column of droplets freely from atomizer was ignited behind a reflected shock.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1069-1074
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• 1999

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.57-61
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• 2001

In a main propulsion system of naval ship, DRME(Double Resilient Mounted Engine) is mostly adopted to ensure vibration isolation and shock resistance against underwater explosion weapon attack. In this paper, an analysis program for vibration and shock evaluation of DRME is presented. DRME is modelled as multi-rigid bodies with nonlinear mounts, and direct time integration method is introduced for shock analysis. The computed results are compared with those of foreign ones. Navy's proposed specifications are well satisfied with this program. This analysis program serves for the development of domestic DRME technology of naval ship.

• Journal of KSNVE
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• v.4 no.3
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• pp.345-352
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• 1994

Electronic products can be subjected to many different forms of shock. These shocks are usually experienced during transporting the electronic products from a manufacturer to customers. Drop tests are performed to test the product fragility before shipment. Package cushioning materials are often used to protect electronic products from severs shock environments. In the present paper, an algorithm to predict the shock responses of the main mechanical parts is developed by use of the shock analysis in which the modal parameters extracted from vibration test are used. These results are in good agreement with the results of drop test. By use of the shock response prediction algorithm developed herein, it is possible to predict the results of drop test at various drop directions and also to select the optimal package cushioning materials.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.147-154
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• 2001

The underwater explosion shock test is performed for the evaluation of the shock-resistant capability which is a very critical factor considering the survivability of the battle ship. Some measured signals have impulsive noise and gaussian white noise because of the unstable power supply system and the transient movement of cables during the underwater explosion shock test. The advanced shock signal analysis method which remove the noise of measured signal using the threshold policy of the median filter and the orthogonal wavelet coefficients are proposed. It is verified that the signal-to-noise ratio was improved about 30㏈ by the numerical simulation.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.167-177
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• 2003

In this study, a mathematical nonlinear dynamic model is introduced to predict the damping force of automotive shock absorber. And 11 design parameters were proposed for the sensitivity analysis of damping force. Design parameters consist of 5 piston valve design parameters, 5 body valve design parameters and 1 initial pressure of reservoir chamber air. All of these design parameters are main design parameters of shock absorber in the procedure of shock absorber design. The simulation results of this paper offer qualitative information of damping force variation according to variation of design parameters. Therefore, simulation results of this paper can be usefully use in the design procedure of shock absorber

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1440-1447
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• 2015

This paper describes a study for anti high-shock design of MEMS vibrating ring gyroscope. Structure models was made by MEMS technology processing. MEMS Vibrating Ring Gyroscope mechanical structure were not only anti-high shock simulated with the LS Dyna Ver 971 software but also with mathematical analysis and the finite element method in order to confirm the shock reliability. Shock test result of a MEMS vibrating gyroscope being developed to have gun-hardened survivability while maintaining tactical grade navigation performance for application to various guided projectiles.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.11-16
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• 1997

In the stroke sensitive shock absorber, the oil path is formed along the internal cylinder surface to make the oil flow during the piston's upper-lower reciprocation movement. In constrast with the conventional shock absorbesr which show one dynamic characteristic curve, stroke sensitive shock absorber shows two kinds of dynamic characteristics according to the stroke. In this study, in order to obtain more precise information about design and damping performance analysis, the analysis on the damping force generation process and dynamic behaviour characteristics of stroke sensitive shock absorber are performed by considering the valve characteristics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.987-996
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• 2003

The structural integrity of the reactor vessel with the approaching end of life must be assured for pressurized thermal shock. The regulation specifies the screening criteria for this and requires that specific analysis be performed for the reactor vessel which is anticipated to exceed the screening criteria at the end of plant life. In case the screening criteria is exceeded by the deterministic analysis, probabilistic analysis must be performed to show that failure probability Is within the limit. In this study, probabilistic fracture mechanics analysis of the reactor vessel for pressurized thermal shock is performed and the effects of residual stress and master curve on the failure probability are investigated.

• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.51-55
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• 2013

HDD has been easily exposed to the external shock and vibration because HDD has to apply to mobile devices. Therefore, the stiffness of base has been the important factors for the design of HDD. To improve the stiffness of base, the frame was applied to the base. First, the finite element model of the base was constructed. Then, the FE model was verified by modal analysis. Drop test was performed to confirming the shock simulation model. The dynamic characteristic of original base which is verified is compared with the base which is applied the frame through modal analysis and shock analysis.