• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.673-675
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• 2011

고무는 소재의 탄성 회복 능력과 감쇄 능력, 수밀성의 우수성으로 인해 여러 기계산업의 부품으로 사용되어 지고, 자동차 부품으로는 마운트와 범퍼 등의 충격해소를 위하여 설계되어지고 있다. 본 논문에서는 승차감에 영향을 주는 내부 소음 및 진동의 원인인 엔진의 떨림현상을 감쇄시키기 위한 부품인, 엔진마운트의 고무 모형을 CATIA 프로그램을 사용하여 모델링하였고, ANSYS 12.0 프로그램으로 진동과 하중을 주어 변화량을 측정하여 상용차에 맞는 엔진마운트의 최적설계를 방향을 제시하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.1
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• pp.24-30
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• 1985

An experimental work to predict critical flow velocity to give whirling instability on staggered array tube banks model which is located in wind tunnel is presented. The critical flow velocity was obtained by measuring flow induced tube vibration on three tube array models having different pitch to diameter ratio as changing damping ratio and natural frequency of tube model. The obtained experimental results are directly compared with the numbers of other investigators and partly proved the truth of Blevin's new idea to predict critical flow velocity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.323.2-323
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• 2002

Sloshing of fuel in a liquid propellant tank is an important part of the dynamic and the stability analysis of the rocket. Baffles are installed in a propellant tank to reduce the instability due to sloshing. Multi degree of spring-mass-damper model was used to model sloshing of fuel in an axisymmetric tank. The natural frequencies and damping ratios are estimated. In order to verify the estimated natural frequencies and damping ratios, tests are performed for the real propellant tank of KSR-III with single ring baffle. Results of fuel sloshing analysis are compared with those of tests.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.73-74
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.503-506
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• 2005

The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle (5$\times$5) is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid like the coolant mixing performance and to obtain the Flow-Induced Vibration (FIV) characteristics of the rod bundle over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the bundle prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the small scaled test bundle. For the damping factor of the rod bundle and the grid case at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the rod bundle is about 0.7% with reasonable error of 2% for the previous results. Nonlinear behavior of the rod bundle might be stem mainly Iron the rod-grid support configuration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.563-564
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• 2010

A Numerical analysis of preventing pressure oscillation for the supersonic inlet of IRR at the boosting mode was conducted in this study. To reduce the fluctuation of pressure, the supersonic inlet was equipped with annular slit. By decreasing the entrained air mass, the amplitude of fluctuation and maximum pressure at the inlet were decreased while the frequency was increased. In case, the optimal trade-off value is obtained between frequency and amplitude, it is expected that the pressure oscillation declining method using the slit will be helpful in various boosting and transition mode problem for IRR.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.33-39
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• 2006

Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 3 Kyoungju region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy In frequency domain. Average stress drop of 3 events and local attenuation parameter ${\kappa}$ were estimated to about 48-bar and 0.0312 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 417 and 0.83. ${\kappa}$ values are much higher than that of EUS, even though smaller than that of WUS. All these values resultant from this study show that there are differences in some parameters of other studios due to differences in the governing equation. of acceleration motions

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2844-2850
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• 2015

Rolling noise caused by the contact between the train wheels and rails is the main factor of noise generated by the operation of railway, therefore the features of rail vibration and its correlations with noise radiation should be identified. In this study, noise radiation generated from vibration were predicted by utilizing FE model with boundary element method. Noise radiation generated from vibration were predicted by utilizing FE model with boundary element method, and were compared with the measured noise in order to validate the reliability of the analysis method. In addition, the features of noise radiation according to the rail attenuation were examined in the frequency domain, and the noise radiation has been reduced by approximately 3dB(A) with additional rail damping.

• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.52-57
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• 1994

본 개발에서는 주로 진동응답의 추정법에 대하여 검토하고 큰 성과를 얻었다. 이를 실제 설계에 활용해 나가는 것이 앞으로의 기본적인 과제이다. 또 이를 앞으로도 계속 개발해 나가기 위해서 는 다음과 같은 개발과제들을 들 수 있다. 1) 진동응답추정 .계산model 본 계발에는 Oil tanker와 산적화물선의 in-put generator(I/G)을 개발하였다. 이 이외의 선종 에 대하여도 본 개발에 의한 방법을 적용하게 되면 보다 정도 높은 계산 model로 새로이 refine해 나갈 수가 있다. .실선mode 해석전용 본 개발에 의하여 얻은 실선 mode해석 방법에 의하면 실선 계측으로부터 정확한 진동질량(m) 과 감쇄계수(d)를 얻게 된다. 이와 같은 m값과 d값의 자료를 더 축적하게 되면 진동응답 계 산정도를 한층 더 높일 수 있다. 2) 진동 제어 .종래의 설계방법과 본 개발에 의한 계산방법을 종합 적용하게 되면, 최적의 구조설계의 실용화 와 진동의 제어가 가능하게 될 것이다. .Enging, propeller 자체의 기진력을 경감시키는 연구는 본 개발에 들지 않고 앞으로의 과제로 남는다. .본 신형 주기방진stay의 개발은 본 진동제어의 idea에 도입하게 되면 또 다른 새로운 개발이 가능하다. .종래의 재료와 새로운 고성능 재료를 조합하게 되면 진동재어재료로서의 실용화가 가능하다.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.202-203
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• 2007

STATCOM은 계통에 무효 전력을 공급함으로써 모선 전압을 유지시키는 역할을 한다. 따라서 발전기들의 회전자 위상각과 같은 유효전력과 관련된 계통 변수들의 제어 능력은 없다. 그러나 여자기에 PSS와 같은 제어기를 설치하여 발전기 회전자 진동을 제어하는 것처럼 STATCOM에도 이러한 제어기를 설치함으로써 부가적인 효과를 얻을 수 있다.