• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.619-626
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• 2006

Body-on-frame type vehicle has a set of frame bushes between body and frame for vibration isolation. Such frame bushes are important vibration transmission paths to passenger space for excitations during driving. In order to reduce the vibration level of passenger space, therefore, change of complex stiffness of the frame bushes is more efficient than modification of other parts of the vehicle such as body, frame and suspension. The purpose of this study is to reduce the vibration level for ride comfort by optimization of complex stiffness of frame bushes. In order to do this, a simple finite element vehicle model was constructed and complex stiffness of the frame bushes was set to be design variables. The objective function was defined to reflect frequency dependence of passenger ride comfort. Genetic algorithm and sub-structure synthesis were applied for minimization of the objective function. After optimization level at a position of interest on the car body was reduced by about 43.7 % in RMS value. Causes for optimization results are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.96-99
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• 2005

Noise and vibration generated by heavy-weight floor impact in apartment buildings were studied. The resonance frequency increased in the floor structures where damping materials were used in the living room and the bedroom. Both the acceleration wavelength and the acceleration level decreased. The results showed that the resonance frequency increased and vibration acceleration level decreased when the damping materials were used. Heavy-weight impact sound levels of the structure decreased substantially below 80Hz.

• Journal of KSNVE
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• v.9 no.3
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• pp.477-484
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• 1999

This study aims to present proper thickness of resilient mount and pattern of chips for the improvement of impact sound isolation. To achieve this aim, field tests were performed to evaluate the performance of impact sound isolation of pilot samples using waste tire chips against light and heavy-weight impacter, which samples were installed over concrete slabs of an apartment housing. In this study, the experiments were performed by the impact sound level of floors in KS F 2810 "Method for field measurement of floor impact level". As results, a flooring structure using waste tire chips as a resilient mount, with no relation to chip's types, has enhanced performance by 1~2 degree in light impact sound isolation, while it has improvement in heavy impact sound isolation. And fiber-type chips have better performance than granule-type ones when they overlaid concrete slab with 15~20 mm of thickness. For the improvement of impact sound isolation, it is recommended that insulating materials should be applied at joints between floating floors and walls, or floating floors and a doorframes, and also waterproof papers should be used for the effective thickness of resilient mount.ent mount.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.207-212
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• 1993

When constructing highly precise production plants, for example, super LSI plants or semiconductor plants, it is important to take the necessary control countermeasures into consideration to obtain the working microvibration environment, which is directly related to product precision. Working environment of a clean room means vibration-free and there are only ultra-miro vibration which human cannot sense. In order to provide an place having a vibration-free working environment with only ultra-micro vibration it is necessary to posses a great number of vibration isolation technlogies, wide-ranging and abundant survey and teat data, and a high level of knowledge enabling comprehensive judgments to be made. In this study, experimental modal analysis is used to analyze the dynamic characteristics of double floor for vibration-proofing near apparatus which generate vibration. It is concluded that the double floor system with rubber pad inserted between floor panel and pedestal is good for vibration proof.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.816-821
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• 2013

This case study presents a practical method to reduce resonant vibration of generator-motor set. The generator is driven at 1800rpm by induction integral motor. The vibration is below alarm limits, but the dominant frequency of vibration is sub-synchronous and close to that of bearing fault signal in spite of new bearings. To find an mechanism of abnormal vibration, ODS and Modal analysis is carried out. The measured modal characteristics were compared with those of FE Analysis. The ODS mode at rated speed is consistent with system natural frequency mode that is excited by bearings. To reduce vibration level, the isolation mount at system base is changed with new rubber mount for lower natural frequency.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.145-151
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• 2019

In this study, the effects were analyzed by applying the vibration absorption liner into the guide rail bracket as a part of method to reduce the vibration and noise on the high-rise apartment. As the result of vibration absorption liner performance, it was checked that the level of vibration and noise was reduced around 65.49% in the car side and around 90.05% in the counterweight side. Therefore, the vibration absorption effect by the vibration absorption liner of elevator guide rail bracket became fairly good. In case of the vibration absorption liner application, there was an effect on the reduction of 7.26 to 22.22% at hoistway section area, 3,840,000 to 9,780000 KRW at the cost of material and installation by comparing with the damping beam application. Also, in case of the vibration absorption liner application with light weight instead of damping beam with heavy weight, it was thought to become significant effect at preventing the safety from the accidents on installation site.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.194-199
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• 2005

Body-on-frame type vehicle has a set of frame bushes which are installed between body and frame fur vibration Isolation. Such frame bushes are important vibration transmission paths to passenger space. In order to reduce the vibration level of passenger space, therefore, the change of complex stiffness of the frame bushes is more efficient than modification of other parts of the vehicle such as body, frame and suspension. The purpose of this study is to reduce the vibration level for ride comfort by optimization of complex stiffness of frame bushes. In order to do this end, simple finite element vehicle model was constructed and the complex stiffness of frame bushes was set to be design variable. Objective function was defined to reflect passenger ride comfort and genetic algorithm and sub-structure synthesis were applied for minimization of the objective function.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.186-190
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• 2011

The Line-Of-Sight stabilization system is designed to minimize the error of Line-Of-Sight under the disturbing circumstances. In order to control this system more accurately and reduce the level of the disturbance, adding an isolator is mostly considered. However, it is difficult to predict the exact the behavior of the isolator and the effect of a stabilization Error. Therefore, the simulation model of the control system using co-simulation with Adams and matlab simulink is presented and the effects of the isolation properties are reviewed.

• International Journal of High-Rise Buildings
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• v.6 no.3
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• pp.227-235
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• 2017

This paper describes some of the challenges for structural design of a mid-story seismic isolated high-rise building, which is located near Tokyo station, completed in 2015. The building is a mixed-use complex and encompasses three volumes: one substructure including basement and lower floors, and a pair of seismic isolated superstructures on the substructure. One is a 136.5m high Main Tower (office use), and the other is a 98.5 m high South Tower (hotel use). The seismic isolation systems are arranged in the $3^{rd}$ floor of the Main Tower and $5^{th}$ floor of the South Tower, so that we call this isolation system as the mid-story seismic isolation. The primary goal of the structural design of this building was to secure high seismic safety against the largest earthquake expected in Tokyo. We adopted optimal seismic isolation equipment simulated by dynamic analysis to minimize building damage. On the other hand, wind-induced vibration of a seismic isolated high-rise building tends to be excited. To reduce the vibration, the following strategies were adopted respectively. In the Main Tower with a large wind receiving area, we adopted a mechanism that locks oil dampers at the isolation level during strong wind. In the South Tower, two tuned mass dampers (TMDs) are installed at the top of the building to control the vibration. In addition, our paper will also report the building performance evaluated for wind and seismic observation after completion of the building. In 2016, an earthquake of seismic intensity 3 (JMA scale) occurred twice in Tokyo. The acceleration reduction rate of the seismic isolation level due to these earthquakes was approximately 30 to 60%. These are also verified by dynamic analysis using observed acceleration data. Also, in April 2016, a strong wind exceeding the speed of 25m/s occurred in Tokyo. On the basis of the record at the strong wind, we confirmed that the locking mechanism of oil damper worked as designed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1123-1128
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• 2006

철도 및 도로교통에 의한 건축구조물의 진동, 소음을 저감시킬 수 없는 PO-MAT(Polyurethane Mat) 제품과 다양한 건축물의 진동, 소음이 전달되는 상황에 적용되어 방진효과를 정확하게 예측하는데 사용될 수 있는 설계안을 개발하였다. 개발된 제품은 다공질의 폴리우레탄 탄성체의 조직으로 도로 및 철도의 교통진동의 방진과 연구실, 기계실, 공조실 등의 Floating Floor System 및 건축기초의 내진용으로 사용되고, 실제구조물에 적용하여 진동저감과 충격흡수, 소음저감 효과가 탁월함을 확인하였다.