• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.229-236
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• 2020

A crush switch assembly(CSA) connected to an impact fuze provides electrical signal for detonation of the loaded main charge when an impact with the target is detected. Because the CSA experiences continuous changes in flight environment such as changes in velocity, vibration, and stresses, it is necessary to accurately predict the behavior of the fuze to maintain functionality during flight and to detonate when necessary. In this paper, random vibration analysis for flight environment and impact analysis on target hit are performed using FEA. Then, high speed impact tests are performed with the original and scaled down models to ensure operation validation of the manufactured products. The test results are then compared with M&S results to verify the capability of currently modeled CSA.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.389-393
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• 2014

This paper presents one of the methods for design to reduce the noise and vibration of 200kW motor for electric propulsion ship. One of the important factors affecting vibration of the motor is the resonance. The natural frequency and natural mode of the 200kW motor is analyzed by using FEM tool and impact test equipment to avoid the resonance. Also, compare FEM result with impact test result to make a reliable FE model of 200kW motor. In order to find out the effect of the noise and vibration of the motor by electromagnetic excitation force, conduct electromagnetic-structure coupled analysis. These characteristics are much useful to design 200kW motor for electric propulsion ship.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1455-1458
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• 2007

Vibration characteristics of concrete slabs were investigated using a 1:10 scale model and finite element method. A 1:10 scale model of a test building with 150 and 200mm slab thicknesses was made of acrylic materials. Modal test was conducted to investigate mode shape and modal frequencies. Results show that the mode shapes of two slabs with different thickness are similar each other, whereas natural frequency is different. Through modal analysis using FEM, it was revealed that both mode shapes and natural frequencies calculated from the FEM model are similar to those of the scale model measurement. It was also found that natural frequencies increased with increment of the slab thickness.

• Journal of KSNVE
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• v.7 no.3
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• pp.511-519
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• 1997

For a number of years it has been known that flexural vibration in a beam and plate can be damped by the application of layer of damping (viscoelastic) material that is in turn constrained by a backing layer or foil. In this study, a quantitative analysis of damping of the sandwich beam has been performed by using impact test. The damping is characterized by the loss factor .etha. in which the damping is normalized by imaginary part of the complex bending stiffiness of the beam. Results show that the relative thickness of the sandwich beam gives more effect on the riatural-frequencies and loss factor than the variation of width does. It is also shown that the Ross-Kerwin-Ungar equation and impact test can be effectively used to identify the damping characteristic of the sandwich beam and viscoelastic material.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.498-503
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• 2009

This paper presents the vibration problem of the Engine Casing (E/C) "B" deck in the handymax vessel and describes a method to avoid resonance. The first ship of the series did not have any vibration issue on the "B" deck. However, resonance condition occurred when additional machine was installed to the following vessels. To understand the dynamic characteristics of the deck, the normal mode analysis and impact test have been performed. Within the normal operating range of the vessel, the $1^{st}$ natural frequency of the E/C "B" deck is close to the main engine's $6^{th}$ order. Based on these analysis, a reinforcement on the deck was suggested and it proved to be effective. Since actual impact test after the reinforcement also confirmed the resonance avoidance.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.82-88
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• 1999

In order to execute the major role as the high density large capacity data storage device, which is one of the major characteristics of DVD(Digital Versatile Disk), there must be a method to effectively absorb the external impact or internal vibration. The DVD which has been developed until now tries to control two different types of vibrations, using only one absorber. But this goes against the independence Axiom of Axiomatic Approach which makes the design to be coupled. And in fat most of the malfunctions occurring during DVD data input/output is due to impact or vibration. Therefore in this paper, the vibration absorption system and operation reliability of DVD will be evaluated with the Axiomatic Approach and plans and feasibility to design an improved vibration absorption system will be provided also based on the Axiomatic Approach.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.261-262
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• 2014

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.1
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• pp.1-10
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• 2013

In this study, impact vibration tests are applied to analyze the vibration characteristics of caisson-type breakwater, and the results obtained from vibration tests are compared with numerical simulation results considering fluid-soil-structure interaction effects to verify the feasibility of a numerical analysis model. It is found that natural frequencies are reduced as amount of 1.7-4.3% after additional parapet structure is added to increase the height of breakwater, and the same results was observed from the numerical simulation study. Through the comparison, it was verified that the vibration tests and numerical simulation study can be applied to evaluate the vibration characteristics of caisson-type breakwater.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.3
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• pp.77-81
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• 2009

There has been an increasing demand on measurement of the vibration levels in commercial truck shipments, where all packaged products are exposed to some levels of random vibration and shock. In this study, bear glass bottles loaded at the front, middle, and rear positions of 11 tonne truck bed was shipped from Kwangju to Waegouan. Vertical direction vibration levels were analysed and matching laboratory random vibration test was performed using power spectral density (PSD) profiles derived from truck transit records. Also, the effects of drop hight on glass bottles were evaluated. As expected, the maximum vibration levels were recorded at the rear of truck bed. No breakage of bottles were observed during truck transit and laboratory random vibration testing set at 0.52 $G_{rms}$. In drop test, glass bottles were not damaged by bottom side impact, while short side drop impact caused about twice higher bottle breakage rate than that of long side drop impact at 30 cm and 40 cm drop hight.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.273-278
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• 2014

This study presents a chatter vibration avoidance program for the milling process. Chatter vibration has a negative effect on workpieces and spindle-tools. When chatter vibration occurs, the cutting tool is loaded dynamically, a chatter pattern is generated on the workpiece, and the tool life is reduced. The developed program is composed of various modules such as an FFT analyzer, an impact test analyzer, a chatter vibration indicator, and a spindle speed recommender. The proposed program is verified using an AISI D2 cutting experiment in milling process. The effect of chatter vibration on the machining condition can be simulated by the suggested method, and successfully exploited to avoid chatter vibration.