• 환경영향평가
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• 제22권4호
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• pp.381-387
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• 2013

In order to improve the environmental vibration, it is necessary to method for not only reduce the vibration source, but also control the vibration path. In this study, we used borebole for estimate the vibration reduction. And also, we analyzed displacement and vibration velocity caused by the position of borehole as well as the condition of borehole in ground structure. Visual FEA(Finite Element Analysis) program was used in this numerical analysis. The results are as follows : The displacement magnitude and X, Y direction displacement were represented to different results due to the condition and position of borehole, and were represented to the lowest values when the position of borehole is the most close condition from the vibration source. And also, the vibration velocity was decreased as using borebole in ground structure. The isolation efficiency of the vibration was calculated to maximum 18.40% when borehole was established to the most close position from the vibration source and the receive point.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.866-871
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• 2005

In this paper a study on the characteristics and the reduction method for the ground vibration due to traveling tilting car is carried out. The transmitted load which induces the ground vibration is computed through a study oil the interaction between tilting car and the line. Then, this lead is applied into the numerical model, which is not only designed considering the diverse ground conditions hut also verified by the ultrasonic experiment. Through the numerical analysis according to the conditions, the characteristics and the reduction method for the ground vibration by tilting car are studied.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1104-1110
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• 2003

The present study investigates the hemorheological characteristics of blood flow with applying vibration to a non-aggregating red blood cell suspension. In order to obtain the non-aggregating RBC suspension, blood samples were treated with vibration at a specified condition, which viscosities were taken before and after the treatment, respectively. The viscosity of the blood samples after treatment was higher than before treatment. These treated blood samples were forced to flow through a capillary tube that was vibrated perpendicularly to the direction of the flow. The experimental results showed that vibration caused a reduction of the flow resistance of the non-aggregated blood. The reduction of the flow resistance was strongly dependent on both frequency and amplitude of vibration. These results show potential in treating various diseases in the microcirculation associated with blood cell aggregation.

• 소성∙가공
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• 제25권6호
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• pp.373-378
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• 2016

Recent researches have reported that the superposition of ultrasonic vibrations in metal forming provides beneficial effects such as the reduction of forming load, flow stress and interfacial friction which improves the surface quality of end products. This paper presents experimental investigations on the effects of ultrasonic vibrations in upsetting tests of aluminum. The ultrasonic exciting system consists of piezoelectric transducer and resonator was designed and constructed to superimpose high frequency oscillation on the forming tools. Ultrasonic vibration-assisted upsetting tests were performed for three vibration modes five amplitudes, and the results were compared with those of conventional upsetting tests. The results showed that the superimposition of ultrasonic vibration reduces the upsetting load, and the load reduction is only dependent on the amplitude of the applied vibration regardless of deformation histories and vibration modes.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.102-111
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• 1995

The non-periodic fluctuation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration has become a significant problem along with the requirements of higher performance. The torsional vibration of the automotive driveline can be reduced by smoothing the fluctuation by adjusting the torsional characteristics of the clutch-disc. Computer simulation of the driveline is a useful investigative tool on studying the torsional characteristics of the clutch-disc. In this paper, a dynamic model for the automotive driveline was developed, and the engine torque of the model were evaluated with experimental data. By executing a simulation using the model, it has become possible to obtain the clutch-disc torsional characteristics for reducting the torsional vibration at creeping.

• 소음진동
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• 제4권3호
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• pp.319-325
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• 1994

The flucturation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration has become a significant problem, due to an increase in the flucturation of the torque of recent light weighted powered engines, along with the requirements of higher performance. The torsional vibration of the automotive driveline can be reduced by soothing the fluctuation by adjusting the torsional characteristics of the clutch-disc. Computer simulation of the engine- input gear train is a useful investigative tool on studying the torsional characteristics of the clutch-disc. In this paper, a dynamic model for the automotive driveline was developed, and the engine torque and drag torque of the model were evaluated withe experimental data. By executing a simulation using the model, it has become possible to obtain the clutch-disc torsional characteristics when the engine is idling and the clucth-disc torsional characteristics for reducing the torsional vibration has been suggested.

• 한국소음진동공학회논문집
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• 제22권1호
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• pp.74-80
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• 2012

The vibration of a LP turbine case may cause the failure of power generation and reduce the life of its facility. In this study we carried out on-site measurements of a LP turbine in order to find the cause of the vibration and conducted experimental and numerical modal analysis of the turbine case with its support frame. The measurement and the modal analysis show that the natural frequency of the turbine becomes close to 60 Hz due to the subsidence of the support. The elimination of the subsidence by shimming between the turbine and the support frame gave rise to the reduction of the vibration of the LP turbine case.

• 한국생산제조학회지
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• 제6권2호
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• pp.67-75
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• 1997

The noise . vibration characteristics of Hypoid gears which were made from three seperate materials(SCM, TSCM, SNCM) under the identical process were investigated for the sake of durability improvement of differential gear compatible with low level noise gear set. For this study, we developed a rig experimental equipment which can perform close noise.vibration experiment of differential gear. Consequently, we could analyze the noise.vibration characteristics of final reduction gear by materials, and also we observed changes in both metallic structure and hardness according to the materials of pinion gear. In addition to this, the correlation between the vibration of the differential gear and the interior noise of the passenger vehicles was proved by analyzing the results of rig vibration experiment and field noise test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.384-389
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• 2011

The vibration of a LP turbine casing may cause the problems of power generation and the life of its facility. In this study, we carried out on-site measurements of a LP Turbine in order to find the cause of the vibration and conducted experimental and numerical modal analysis of the turbine with its support frame. The measurement and the modal analysis show that the natural frequency of the turbine becomes close to 60 Hz due to the subsidence of the support. The elimination of the subsidence by shimming between the turbine and the support frame gave rise to the reduction of the vibration of the LP turbine case.

• 융복합기술연구소 논문집
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• 제9권1호
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• pp.21-24
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• 2019

This research presents an development of impact damper for reduction of vehicle vibration from road excitation. The structural vibrations are transferred through the vehicle body. The impact damper for reducing structural vibration from road excitation were designed and derived by using simplified numerical model. To analyze the characteristics of the impact damper, the vibration of simplified beam attached to impact damper was simulated. The damping ratios for different mass ratios of the impact dampers were calculated. The numerical results can be utilized to reduce the radiated noise from the electric vehicle.