• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.129-133
• /
• 2004

This paper is the result of a experimental study about non-linear one to one modal coupling of a flexible circular cantilever beam which was transversely excited with harmonic excitation. It was proved that 2 order jumping in out of plane was caused by jump phenomenon in in-plane of flexible circular cantilever beam, because of non-linear coupling. In addition, cantilever beam showed hardening spring characteristics in in-plane and softening spring characteristics in out-of-plane.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.42 no.1
• /
• pp.7-12
• /
• 2005

It was analyzed that the vibration and frequency characteristics for quartz crystal using a finite element method, ANSYS. It was investigated that the resonant frequency of quartz crystal by fixing the diameter of quartz crystal for the various its thickness. There were also studied that the resonant frequency value with different electrode thin films of Au, Ag and Al. As the result of this study, the best condition for quartz crystal unit was determined by the finite element method. If the thickness of quartz crystal is smaller than 0.2 mm, the high frequency over 8.102 MHz was obtained. In addition, as to the change of resonant frequency on electrode thin film, Al turned out to be superior to Au or Ag in frequency response.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.10a
• /
• pp.850-854
• /
• 2009

Approximate analysis for a building installed with a friction damper is revisited to get insight of its dynamic behavior. Energy balance equation is used to have a closed analytical form solution of dynamic magnification factor (DMF) for the building with combined viscous and friction damping. It is found out that DMF is dependent on friction force ratio and resonance frequency. Linear transfer function from input external force to output building displacement is obtained by simplifying DMF equation. Root mean square of building displacement is derived under earthquake-like random excitation. Finally, design of friction damper is proposed by processing target control ratio, damping ratio factor, and friction force in sequence.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1995.10a
• /
• pp.74-79
• /
• 1995

모우드 밀도의 산정을 정확하게 구하기 위해 고주파수 영역에서 흔히 적용되는 3채널 측정법이 저주파수대 영역에서도 2채널법에 의한 방법보다 주파수 응답함수의 크기 및 공전주파수의 위치를 보다 더 잘 나타내 주고 있다는 것을 실험적으로 제시하였다. 2채널 측정법에 비하여 3채널 측정법이 모우드 밀도가 균일한 보의 경우에 있어서도 주파수 응답함수의 크기를 실제의 경우와 근접하게 추정해 줄 수 있을 뿐 아니라, 상대적으로 모우드 밀도가 높은 평판의 경우에 있어서도 공진주파수 대에서의 주파수 응답함수의 형태를 보다 분명히 나타내어 줄 수 있는 것으로 나타났다. 한편, 구조물과 가진기의 상호작용에 의한 고유진동수의 변동량 측정의 관점에서는 2채널 측정법과 3채널 측정법의 경우 모두 주파수 응답함수를 적절히 나타내어 주고 있는 것으로 나타났다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.11
• /
• pp.996-1002
• /
• 2013

Conditions of stiffness for a steel spring torsional vibration damper are difficult and ambiguous. Nevertheless correct estimation of stiffness is essential and important in the damper design for the damper to activate properly in the field. In this paper, to build up the estimation method of steel spring torsional vibration damper a miniaturized model was developed for modelling between a spring and inner star of the damper. The method obtained from the results through the experiment and analysis of it was applied to the prototype torsional damper.

• Proceedings of the Korean Reliability Society Conference
• /
• 2004.07a
• /
• pp.297-301
• /
• 2004

세탁기의 Shaft Ass'y는 모터로부터 동력을 전달 받아 세탁 및 탈수행정의 제어 기능을 수행하는 세탁기의 핵심부품으로 사용 중 브레이크 밴드소음을 유발하여 소비자의 불만족 요소로 작용하고 있다. 그러나 드럼과 브레이크 페드의 정확한 마찰소음 현상 규명이 안되어 불량 개선에 많은 어려움이 있다. 이를 해결하고자 소음, 진동, 소재 분석 및 ESPI(Electronic Speckle Pattern Interferometry) 분석을 통해 고장원인을 규명하였다. 특히 ESPI는 비접촉, Full Field 정밀 변형 가시화 장치로 Shaft Ass'y의 동작 중 공진소음 발생 부위를 변형 가시화를 통해 정확하게 찾을 수 있었다. 밴드소음 원인은 브레이크 Lever의 공진에 의해 발생하였고 브레이크 밴드 패드의 접촉면적 불균일로 인한 국부적 마찰력 증대가 소음원으로 작용하였다. 밴드소음의 정확한 고장 메커니즘 규명을 통해 개선안을 도출하여 적용하였고 밴드소음 개선효과를 얻을 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.877-880
• /
• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the substrate effect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.11
• /
• pp.932-937
• /
• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the rectangular substrate affect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration. And frequency constant for length extensional vibration becomes slightly small as the substrate thickness becomes thin, but it does not change as its length changes. Electro-mechanical coupling factor for length extensional vibration, k$\_$31/ does not change as its length changes within length/width$\geq$4, but it becomes small as its width increases.

• Journal of the Korean Society of Visualization
• /
• v.18 no.3
• /
• pp.14-22
• /
• 2020

An experiment, in the cases that satisfies deep water condition, has been performed to observe the strongly nonlinear sloshing flow in a rectangular tank. A variety of parametric study on oscillating frequency and amplitude was conducted and we found that two types of wave motions, sloshing wave and Faraday wave, could be persisting simultaneously even in horizontal sloshing problem. Moreover, it is observed both of symmetric and skewed symmetric Faraday wave exist. A comprehensive explanation is given to the generation mechanism of those waves and how to interact among them.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1992.04a
• /
• pp.285-290
• /
• 1992

기계 구조물의 과도한 진동은 기계의 성능 및 수명에 나쁜 영향을 미치며 기계및 부품의 파괴까지 유발하게 되는 원인이되므로 이를 제진하기위한 각종 방법이 오래전부터 연구되고 있다. 본 연구에서는 현재까지 진행된 충격식 댐퍼의 이론을 기초로 한 사이클당 두번의 충돌이일어난다는 가정하에, 파라메타 의 변화에따른 최적 감쇠특성을 얻기위한 최적간극과 최적 질량비를 쉽게구할 수 있는 식을 유도하였다. 그리고, 실험에 의하여 공진상태에 있어서 불의 충격력에 의한 감쇠특성을 조사하였고, 이론으로구한 식과 비교 검토함으로서, 실제 현장등에서 간편하게 근사식을 이용하여 최적조건을 구하고, 이 자료를 기초로하여 설계, 제작시 보다 간편하게 사용할 수 있도록 하였다.