The multi-local resonance metamaterial is based on the local resonance mechanism of resonators, effectively blocking wave propagation within multiple resonant frequency ranges, a phenomenon known as band gaps. In practical applications for vibration reduction, the goal is to achieve wide-band vibration attenuation at low frequencies. Therefore, this study aims to improve the vibration reduction performance of multi-local resonance metamaterials by lowering the band gap frequency and expanding the band gap width. To achieve this, an objective function was formulated in the optimization problem, considering both the frequency and width of the band gap, with the geometric shapes of the multiple local resonators selected as design variables. The Sequential Quadratic Programming (SQP) technique was employed for optimization. The results confirmed that the band gap was generated at lower frequencies and that the band gap width was expanded.

In order to prevent disconnection of the hydraulic pump EDV cable, this study judged the vibration generated by the pump as the greatest effect on disconnection, and confirmed the vibration effect. And it had a structure that was vulnerable to vibration because of the wire flow space inside the EDV cable connector. After applying the improved adapter, vibration analysis, excitation test, and bending strength test were performed to confirm the effectiveness of design change and improvement. As a result of vibration analysis, the amount of vibration was reduced by about 10 times compared to the existing product, and the strength increased by about 4 times in the bending strength test was confirmed to increase the effect of preventing disconnection due to vibration.

Generally, vibration absorber systems are composed of spring-mass systems to reduce the vibration of a structure, and there are also methods to simply increase damping to achieve a damping effect across a wide frequency band. One similar method is to use a mechanism in which the eddy current is converted into a mechanical damping effect. When an eddy current is generated by electromotive force due to magnetic flux change, the reaction force is generated by the eddy current’s circulation. In this study, the damping system using the reaction force was constructed to reduce the transmission of vibrations generating from internal fluid and the vibration reduction characteristics that are transmitted externally were analyzed. As a result, 8.2 % of the vibration reduction effect from primary excitation frequency was confirmed.

In this study, the yaw misalignment value of wind turbine was measured using Lidar and it was analyzed the effect of vibration reduction and power performance improvement when applied to turbine. It was confirmed that the vibration of the main bearing and the gear box of the wind turbine was partially reduced. Also it was found that the output performance was improved when the wind speed was over 8m/s. As a result, it was also found that the annual energy production(AEP) was improved when the average annual wind speed of the wind farm was over 6m/s. Converted to AEP, the AEP improved about 1% and 4%, when the annual wind speed was 6m/s and 11m/s respectively, which resulted in an improvement of about 1~4% through the yaw misalignment correction of the wind turbine.

Since the 2010 year, an occurring number of grand scale earthquakes which above magnitude 5.0 have increased in the world. Many types of research that deal with reducing the damage to the structure from a large-scale earthquake have proceeded. A system which could mitigate strong vertical earthquake's acceleration might apply to structure, since big earthquake cases that occurred lots of loss in Tokyo and Kobe of Japan. A plenty of bearings have installed to mitigate vibration but many parts of these lack efficient ability what we want. In addition, former vertical isolation bearings to apply for the structure have both price and size limits according to material characteristics. Therefore, this paper proposes a new type of device that is made by utilized engineering plastic and improves hitherto used vertical isolation bearing's fault.

The characteristics and effectiveness of double tuned mass dampers (DTMD) have been studied by many researchers. DTMD usually consists of one larger mass block and one smaller mass block. In this study, DTMD was proposed to reduce the vibration of vertical pumps in industrial plants. In order to assess the efficiency of the proposed method, numerical analysis for the simplified vertical pump model with single and double TMDs was carried out. It was also investigated that the effects of optimal TMD parameters such as frequency ratio and damping ratio on dynamic responses of the main structure. According to analysis results, DTMD are more effective to control the vibration of the vertical pump and show good robustness to the change in the stiffness of TMD.

Recently, measures for reducing noise and vibration of a railroad station are actively being developed to enhance its property value and comfort level of passengers. In this paper, the applicability of the recently developed vibration mitigation method utilizing a platform TMD (Tuned Mass Damper) by installing a spring-damper system beneath the platform is experimentally verified using a bench scale structure. The two-story bench scale structure is built to simulate a real railroad station, and vibration reduction effect is verified by comparing acceleration before and after applying the platform TMD at the 2nd floor of the structure. The design parameters of the platform TMD system is determined based on vibration analysis result and the MTMD (Multiple TMD) theory recently developed to enhance the effectiveness of the platform TMD method. The vibration is excited to the bench-scale structure using a vibrator. The performance test result for a spring-damper system is also presented. The result of the experiment reveals that the platform TMD method can reduce the vibration of the bench-scale structure by greater than 5dB(V).

Wind tower structure has relatively simple shape compared to other structures, but due to its characteristics, various and irregular environmental loads are applied. These loads cause vibrations at tower, and can cause failure of the structure if over vibration occurs. Vibration occurred at structures is gradually exhausted by damping of the structures, and if high damping is ensured, the failure of the structure due to over vibration can be prevented. In this study, the vibration reduction effects are to be analyzed through FEM analysis by examining the top displacement, bottom moment, and bottom fatigue damage of the structure depending on damping ratio of the wind tower structure.

해상풍력발전의 건설이 여러 가지 환경 및 가설공법 등의 설치환경 등의 원인에 의하여 건설지점이 천해에서 심해로 이동하는 경향을 나타내고 있다. 이러한 경향 속에 해상풍력발전 지지구조물의 심해화에 따른 지지구조물에 대한 연구는 중요성이 더욱 증대될 것으로 판단된다. 본 연구에서는 기존의 Jacket 구조물에 대하여 Precast Concrete Block 및 Suction pile을 적용한 Jacket 구조물을 제안하고 이에 대하여 구조해석 및 안전성 평가를 실시하였다. 또한 제안된 구조물에 동조액체감쇠기를 적용하여 구조물 진동성능 향상을 도모하고자 하였다. 연구결과, 제안된 신형식 Jacket 구조물은 충분한 안전성을 가지고 있는 것으로 평가되었으며, 동조액체감쇠기를 적용하였을 경우, 약 5%의 진동저감 효과가 있는 것으로 검토되었다.

Abnormal cab vibrations in the Y direction in commercial vehicles during driving(70~90kph) are not common vibrations that happen to vehicles during driving and can be an obstacle to normal driving. This study conducted Operation Deflection Shape(ODS) testing to identify the causes of those abnormal cab vibrations and find solutions for them and also a sine sweep test to find resonance and frequency in the cab suspension system and set directions for improvement. The study also altered the shape of the bush inner part for changes to the rigidity features of the cab bush in the Y direction and revised the design with optimal rigidity in the Y direction, thus improving abnormal cab vibrations in the Y direction during driving.

2011년 7월 서울시 구의동에 위치한 테크노마트 건물(39층)에서의 이상진동은 대한건축학회의 원인조사 결과, 휘트니스센터(12층)에서의 집단리듬운동에 의한 건물 전체의 연직진동모드의 공진현상으로 확인되었다. 본 연구에서는 연직진동의 특성과 이를 제어하기 위한 TMD의 설계 및 성능시험에 대하여 기술하고, TMD 설치에 따른 건물 유효감쇠비의 증가량과 진동저감 효과, 그리고 연직진동에 대한 거주성능의 개선정도를 정량적으로 평가하였다.

Instruments for surgical and dental application based on oscillatory mechanics submit unwanted vibrations to the surgeon's and dentist's hands. frequently the weight of the instrument's body is increased to dampen its vibration. Because medical devices to contact with human body directly are sterilized before use, conventional damping method and damper are not good for medical use. For dissipation of vibration, based on recent research regarding the optimization of particle damping, we made a prototype particle damper that dissipate the vibration of oscillatory saw and tested for validation of particle damping. As a result we found that particle damper operate more efficiently than solid mass damper if the geometry of the damper is optimized with respect to the specific amplitude of the vibration.

When the trains are passed the station, a serious force is applied to ground and the caused vibration is propagated to the area of the station by the ground and rocks. The caused vibration brings about the operation interruption of the equipment which is sensitive to the vibration, or will bring about the structural damage of the station. In this study, to investigate the vibrational evaluation of railway station by the train service, the vibration simulation was performed and analyzed the effect of the vibration isolating countermeasure. From the vibration measurement, all trains that passed through the station exceeded the vibration criteria. Therefore, the vibration isolating countermeasure was established and the vibration simulation was performed.

사장교 케이블은 구조적으로 휨강성과 감쇠력이 작아 풍우에 의해 쉽게 유해진동이 발생한다. 이러한 풍우진동을 저감시키기 위한 효과적인 방법으로 부가댐퍼를 장착하여 케이블의 감쇠력을 증가시키는 제어시스템이 널리 사용되어왔다. 그러나 댐퍼를 케이블의 정착부 부근에 설치할 수밖에 없는 구조적 한계로 인하여 충분한 감쇠력을 발휘하기 어렵다. 그러므로 본 논문은 수동제어시스템 보다 효과적으로 풍하중에 의한 케이블 진동을 제어하기 위한 능동제어시스템을 제안하였다. 제안된 능동제어시스템은 케이블의 정착단에 베어링 장치를 장착하여 케이블 단부에서 횡방향 변위가 가능하도록 모델링 하였으며, 앵커리지 내부에 장착된 능동댐퍼를 이용하여 적절한 제어력을 제공하도록 하였다. 능동제어를 위하여 최적제어 이론을 이용 LQG 조정기를 설계하였으며, 수치해석은 실제 교량인 서해대교의 최장 케이블을 대상으로 하여 기존의 댐퍼 시스템과 수동, 능동 댐퍼 부착에 따른 케이블의 진동제어성능을 비교 및 분석하였다. 연구결과 제안된 능동제어시스템은 효과적으로 사장교 케이블의 진동을 저감시킬 수 있는 시스템임을 입증하였으며, 기존의 부가댐퍼 시스템 보다 효과적으로 진동을 저감시킬 수 있을 것으로 사료된다.

In order to simulate the Helmholtz resonator environment, a perforated plate was inserted into a hollow slab to test its vibration performance. The vibration damping ratio was larger in the conventional hollow slab without apertures, however the accelerometer measurement showed a higher vibration reduction effect in the case of the perforated plate.

In this paper, we proposed a method to determine the acceleration/deceleration time of the motion for reducing the residual vibration caused by the resonance of the robot in the high-speed motion. The relationship between the acceleration/deceleration time and the residual vibration was discussed for the trapezoidal velocity profile by analyzing the time when the jerk happens. The natural frequency of the robot can be estimated in advance through the dynamics simulation. The simulation and experiment for both cases where the moving distance of the robot is long enough and the distance is short, are implemented in the 1-DOF linear robot. Simulation and experimental results show that when the acceleration/deceleration time is a multiple of the vibration period, the settling time and the amplitude of the residual vibration become less than when the time is not a multiple.