• Proceedings of the KSME Conference
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• 2000.04a
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• pp.837-842
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• 2000

In this Paper, the vibrational characteristics of a gearbox for epicyclic Rear train have been studied The modal parameters and mode shapes of a gearbox have been computed using ANSYS code. Modal testing was carried out to verity the FEM analysis model. It has been shown that the analysis results are m good agreements with the experimental results. Harmonic analysis has been executed to verify the effect of thickness variance of gearbox housing on the modal response. Analyzing the calculated results, some guides fer optimal vibration response has been deduced.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.66-72
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• 2012

Ultrasonic metal welder is consisted of power supply, transducer, booster, and horn. Precise designing is required since each part's shape, length and mass can affect driving frequency and vibration mode. This paper gives a description of an experimental study of the ultrasonic welding of metals. A horn suitable for 40,000Hz was attached to the ultrasonic metal welder in order to weld Cu sheet. The Cu sheet welding was done with different amplitude, pressure and welding time, and its maximum tension was measured. Maximum tension of 177.99N was obtained when the pressure was 2.5bar, amplitude was 80%, and welding time was 0.34sec. Therefore, excessive welding condition negatively influences maximum tension measurement result.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.174-194
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• 2015

In this paper, an Energy Flow Analysis (EFA) for coplanar coupled Mindlin plates was performed to estimate their dynamic responses at high frequencies. Mindlin plate theory can consider the effects of shear distortion and rotatory inertia, which are very important at high frequencies. For EFA for coplanar coupled Mindlin plates, the wave transmission and reflection relationship for progressing out-of-plane waves (out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave) in coplanar coupled Mindlin plates was newly derived. To verify the validity of the EFA results, numerical analyses were performed for various cases where coplanar coupled Mindlin plates are excited by a harmonic point force, and the energy flow solutions for coplanar coupled Mindlin plates were compared with the classical solutions in the various conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.6
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• pp.42-50
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• 1996

이 논문은 step기둥의 자유진동 및 좌굴하중에 관한 연구이다. 축하중을 받는 변단면 기둥의 자유진동을 지배하는 편미분방정식을 이용하여 축하중을 받는 step기둥의 자유진동을 지배하는 상미분방정식을 유도하였다. 또한 이 자유진동을 지배하는 미분방정식을 이용하여 step기둥의 좌굴하중을 지배하는 상미분방정식을 유도하였다. 유도된 미분방정식들을 Heun방법과 Regula-Falsi방법을 이용하여 고유진동수 및 좌굴하중을 산출할 수 있는 수치해석방법을 개발하였다. 실제 수치해석 예에서는 2개의 step구간을 갖는 회전-회전, 회전-고정, 고정-고정 기둥에 대한 무차원 고유진동수화 무차원변수들과의 관계 및 무차원 좌굴하중과 무차원 변수들과의 관계를 그림에 나타내었다.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.868-873
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• 2004

Recently, The surface-wave method has widely been used for the site investigation due to the economic advantage and the improved reliability. The typical surface-wave methods currently available are SASW method, MASW method and CSW method. The CSW method has a potential of high-quality measurement, but its inherent problems limited its use to the special cases such as the compaction-quality control. The CSW method uses the steady-state harmonic vibration for the seismic source as in the steady-state Rayleigh-wave method, which is superior to the impact source used for other methods. This study proposed a new procedure to solve the inherent problems of the CSW method and to improve the reliability of the CSW measurements. To verify the validity of the proposed in this study, the SASW results were compared with the CSW results for the numerical simulation of the CSW testing. Also, the feasibility of the proposed method was verified using the field measurements at a geotechnical site.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.170-172
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• 1999

This paper deals with modal analysis and displacement of stator in SRM due to electromagnetic forces according to the rotor position. The analysis is performed by using 3 dimensional Finite Element Method(FEM). And, the prediction of resonance speed is achieved from the comparison with current harmonic according to duty ratio of voltage source and the natural frequencies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.5
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• pp.527-534
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• 1987

Two phase voltage controlled oscillation was realized by using the Electronic analog simulation of nonlinear simultaneous 2st order equation in terms of vibration and it's usefullness was sustined. Sinde it is complex and expensive to implement the circuits actually which composits and multiplicate the two phase signal squared respectively, this paper is obtained the simplificotion and switching circuit. The circuit introducced in this paper had propotionality of frequency to control input voltage, rapid response time, and little phase error, also this circuit operated with very low THD(Total Harmonic Distortion) and constant amplitude at higher than 10 :1 of frequency ratio.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.34-39
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• 2015

Experimental studies were conducted on the liquid sloshing characteristics in a spherical tank covered with a flexible membrane. A spherical acrylic tank with 145.2 mm in radius was used as a test tank, and it was half-filled with water. Silicon membranes with 0.2 mm thickness were used as a test membrane with plane or hemispherical types. The test tank was harmonically excited in a vertical direction by an electro-dynamic exciter. In this case, a parametric instability vibration comes up when the excitation frequency is twice the natural frequency. Parametric instability regions of natural modes were measured for three cases, i.e. liquid surface is free, covered with plane membrane and hemi-spherical membrane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.611-616
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• 2011

Two kinds of structural analysis on the shape of the impeller models, and the natural frequency, harmonic vibration analysis is performed on the shape of the impeller and the resonant frequency of the local analysis of vulnerable areas by ensuring the structural stability of the shape of the impeller evaluation.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.171-173
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• 1995

Slot field harmonics exist in air gap due to inevitable slot constructure of induction motors. They give rise to noise by the electromagnetic vibration and mechanical pulsation. We calculate the slot field harmonics for varying the ratio of slot width vs teeth pitch using the carter's coefficent. We computate the flux density in air gap by FEM(Finite Element Method) and analyze it in frequency domain using DFT(Discrete Fourier Transform). We develop the new algorithm mixing FEM with DFT.