• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.784-793
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• 2017

A two-axis gimbal-type X-band antenna mounted on an observation satellite can efficiently transmit high-capacity image data to a ground station regardless of both the satellite position and the orbital motion. However, this X-band antenna induces unnecessary micro-jitter which can degrade the image quality of the high-resolution observation satellite. Therefore, to achieve the high-resolution image quality from the observation satellite, micro-jitters have been required to be isolated. In this study, to resolve aforementioned drawback, we proposed blade gear using a shape memory alloy (SMA) applied to azimuth stage of X-band antenna. To investigate the rotational basic characteristics of the proposed SMA blade gear, we performed rotational static loading test. Futhermore, to evaluate the cycle to failure of the gear, accelerated life test was conducted. The temperature test was conducted to confirm rotational basic characteristics at various temperature conditions. To verify the isolation performance for micro-jitter, we performed micro-jitter measurement test.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.41-48
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• 1985

자동차 태수의 급격한 증가 및 일상생활에 있어서의 자동차 사용할 때간 증대는 곧 개개인의 생 활공간에 대한 자동차의 점유비율이 높아가고 있음을 입증한다. 따라서 거주성, 안락감, 쾌적성 등 종합적 주거환경에 관한 고객의 요구 역시 높은 수준으로 만족되어야 한다. 그러나 연비, 생 산성향상 등 경제적 측면의 요구에 부합하기 위한 자량의 경량화, 소형화 추세는 위에서 언급된 차내 주거환경을 저해하는 여러 가지 난제를 안겨주고 있다. 특히 안락감, 쾌적성의 저해는 가 장 직접적으로 나타나는 문제이며, 이는 차체의 진동입력에 대한 감수성 증대와 진동전달계류의 단서화에 따른 절연능력의 저하에 기인하는 것으로 보인다. 더구나 이와같은 진동문제는 대부분 차내소음을 유발시키며 넓은 주파수범위(홍80-120Hz)에 걸쳐 이들 두가지가 서로 달성되는 경우 가 많기 때문에 대적성의 저해요인으로 가장 크게 주목되고 있다. 자동차 진동 소음의 저감을 위한 노력은 실험적, 이론적 해석방법의 진보에 힘입어 꾸준한 소모로 실현되고 있으며 발생기구, 전달계류, 응답계류을 통틀어 부분적 또는 종체적인 연구가 계속되고 있다. 이와같은 세가지 계류중 전달계류은 발생기구와 응답계류 각각의 특성에 대하여 상호보완적인 역할을 수행해야 하기 때문에 항시 까다로운 요구조건을 안락시키도록 연구되어야 한다. 본고에서는 진동 소음의 전달계류중 가장 중요한 위치를 차지하고 있는 방진고무의 기본적역할 및 이들의 동력학적 측 면에서의 응용원리에 대해 검토하고 최근 급변하는 신기술동향에 대해 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.8
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• pp.543-556
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• 2016

In this work, an insulated coupling test machine for a 5-MW-class wind turbine was designed and developed, along with the public performance testing of a 3-MW-class wind turbine. The results of the device design, development requirements, functional considerations, structural vibration analysis, and the evaluation of the insulated coupling test machine are presented in this study. For the coupling models, thick fiberglass composite pipe insulation, fabricated by filament winding, was considered. Results of three-dimensional finite element analysis conducted using both solid element and shell element modeling were analyzed and compared, considering the effect of thickness. In addition, results from the nonlinear finite element analysis of multiple leaf springs of the laminated disk pack structure were verified and compared with experimental data.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.11 s.116
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• pp.1100-1107
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• 2006

As environmental vibration requirements on precision equipment become more stringent, use of pneumatic isolators has become more popular and their performance is subsequently required to be further improved. Performance of passive pneumatic isolators is related to various design parameters in a complicated manner and, hence, is very limited especially in low frequency range by chamber volume. In this study, transmissibility behavior of the pneumatic isolators depending on frequency and dynamic amplitude are presented. Then, an active control technique, time delay control, which is adequate for a low frequency nonlinear system, is applied. A procedure of applying the time delay control law to a pneumatic isolator is presented and it's effectiveness in the transmissibility performance is shown. Comparison between passive and active pneumatic isolators is made based on simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1247-1252
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• 2007

The machine equipment of the building inside occurs the vibration. In order to reduce this vibration spring, rubber pad is used. But efficiency of this classical mount is restricted at specific frequency. Also maximum efficiency design is complicated. This paper proposes and examines a attached mass isolation system that is used to reduce transmitted vibrations from machines onto their floor support. With attached mass the low frequency performance is improved overall. The performance is showed in 2 degree of freedom model test. And the proposed isolator has been validated by dynamic test and good agreement between theoretical and experimental results has been obtained.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.925-933
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• 2006

Using the physics-based model for the vibration isolation system, the model uncertainties are described. With the model including parameter perturbations, the robust controller to meet the robust performance and stability is designed through $\mu$-synthesis by DK-iteration. The order of controller is reduced by virtue of Hankel norm approximation technique to allow the efficient implementation in the real-time experimental environment without any performance degradation. The performance of the reduced $\mu$-controller is accessed in comparison with the original one. The experiments validate the superiority of the proposed control scheme against the model uncertainties and its applicability with varying payload.

• Journal of KSNVE
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• v.11 no.1
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• pp.141-146
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• 2001

This paper deals with an application of Magneto-Rheological (MR) fluid to a small size mount for precision equipment of automobiles. MR fluid is known as a class of functional fluids with controllable apparent viscosity of fluid by the applied magnetic field strength. A typical MR fluid is a suspension where pure iron particles of 1-20 (m in diameter are dispersed in a liquid such as mineral oil or silicone oil, at the concentration of 20 - 40 vol%. Electro magnetic coil is installed at the bottom of a variable-damping mount filled with MR fluid, and performance of the mount was investigated experimentally. Furthermore, the Properties of the MR Mount on experimental study were explained analytically by mechanical model of the MR mount.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.464-467
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• 2002

This paper presents investigation of damping characteristics of squeeze mode type MR (magneto-Rheological) mount experimentally. Since damping property of the MR fluid is changed by variation of the applied magnetic field strength, squeeze mode type MR mount proposed in the study has variable damping characteristics according to the applied magnetic field strength. Impact and excitation tests were performed to investigate the dynamic properties of squeeze mode type MR mount. Responses of the mount were compared in proportion to the applied magnetic field strength. The experimental results show that the mount can effectively reduce vibration amplitude in a wide frequency range by changing the applied magnetic field strength.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.12 s.117
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• pp.1262-1271
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• 2006

Using the physics-based model for the vibration isolation system, the model uncertainties are described. With the model including parameter perturbations, the robust controller to meet the robust performance and stability is designed through $\mu$-synthesis by DK-iteration. The order of controller is reduced by virtue of Hankel norm approximation technique to allow the efficient implementation in the real-time experimental environment without any performance degradation. The performance of the reduced $\mu$-controller is accessed in comparison with the original one. The experiments validate the superiority of the proposed control scheme against the model uncertainties and its applicability with varying payload.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.166-170
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• 2008

In this study, it proved that transfer path analysis is a proper technique to estimate the interior noise from comparing measured interior noise in case of 3 point supported engine mount system. And the simulation of the vibration isolation for active engine mount using FXLMS algorithm is performed. Also, it verified that reduction of estimated interior noise from transfer path analysis and simulation of the vibration isolation.