• Tunnel and Underground Space
• /
• v.16 no.2 s.61
• /
• pp.189-193
• /
• 2006

Guide line for rock blasting design of the MOCT(Ministry of Construction and Transportation) adopts attenuation equation of du Pont company for blasting vibration. In this paper the validity of the equation is studied by comparing with several equations of Dowding, Devine and author's induced from the domestic vibration data. The equation is inadequately used and predicted values are proved to be underestimated and causes vibration problems.

• Journal of the Korean Institute of Gas
• /
• v.12 no.1
• /
• pp.13-18
• /
• 2008

Vibration velocity induced by earthquakes or external vibration sources is one of the integrity assessment indexes, and is also a representative value used to describe the amount of vibration because it is based on a proportional relationship with the damage scale. In this study, the vibration velocity criterion for structures is first examined. Then, based on the velocity criterion, an integrity assessment is performed. Burial condition is set up based on the "Highway and Local Road Design Criteria" with API 5L Gr. X65 pipeline(D=762 mm). The FE model considers DB-24 vehicle load as a time function with a varying velocity in the range of $20{\sim}160\;km/h$. Maximum vibration velocity occurs at v=80 km/h and decreases after v=80 km/h. The maximum vibration velocity of buried pipeline by DB-24 loads is about 0.034 cm/s. The velocity that occurs is in the range of allowable values for each vibration velocity criterion. The wave propagation velocity was identified based on attenuation law and the minimum value appears at vehicle velocity 80 km/h that has maximum vibration velocity.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.3
• /
• pp.419-429
• /
• 2019

The characteristics of ground vibration have been analyzed by test blasting in southern region of Jeju (layered ground consisting of basalt and clinker). By grasping the principal component of ground vibration and depriving the prediction equations of ground vibration, the propagation characteristics of ground vibration have been compared to the domestic design guidelines. Ground vibration in layered ground has a small amplitude at a short distance. However, it has been confirmed that the vibration energy is transmitted further by virtue of the low attenuation of the ground vibration as it goes to a longer distance. Moreover, the frequency has been confirmed to be low frequency band. The outcome has been defined that it resulted because the clinker layer with a large pore transforms the blasting energy seismic wave with high frequency into a low frequency wave having a long waveform period. In addition, the limits of design guidelines were identified by comparing the ground vibration of Jeju and other bedrock areas. Thus, the necessity of the development of the prediction equations of ground vibration utilized in design that reflect the characteristics of the area has been suggested.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.03a
• /
• pp.174-181
• /
• 2003

The groundborne vibration from moving train loads in tunnels could cause damages on structures and make people uneasy. With an aim at developing basis for effective screening measures, this paper attempts to study the characteristics of propagation and attenuation of groundborne vibration from moving train loads in tunnels considering the effect of joints. The wave propagation problem is modeled by a commercial code FLAC and the results are compared to those from using a finite-element-based code DIANA. It is shown that the groundborne vibration is affected significantly by the location and direction of joints.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.127-128
• /
• 2008

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.508-509
• /
• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.392-393
• /
• 2014

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.196-202
• /
• 1997

A reinforced hydraulic hoses,caiied a resonator hoses,with fixible metal tube are commonly used in automotive power steering hydraulic systems to attenuate and eliminate the objectionable fluid borne noise(pressure ripple) or vibration produced by a pump or steering gear. To achieve better nose attenuation in automotile vehicles, the investigations on propagation and attenuation characteristics of fluid borne pressure ripple in power steering hydraulic ciruit are required. So, this paper descibes a mathematical model of hydraulic hoses to support design the power steering hydraulic circuit and analyze the attenuation characteristics of flow and pressure ripples. The model is based on the transfer matrix approach. The experimental results show that the pulsation attenuation characteristics of hydraulic house is remarkably affected by the flexible metal tube inserted coaxially inside a hydraulic hose with a finite length as well as viscoelastic properties of house wall. It is also shown that the predicted results bymodel proposed here agree well with the measured results over a wide frequency range. These results will assist in the modeling and design of hydraulic hoses, and hear, should provide a means for designing a quieter automotive power steering hydraulic systems.

• Earthquakes and Structures
• /
• v.24 no.3
• /
• pp.193-204
• /
• 2023

The concept of meta-material-based isolation systems (MMIS) for structural columns has been revisited in the present study in order to enhance the stability of rubber pads by using steel shim reinforced rubber (SSRR) layers. Analytical calculations have shown a significant improvement in the stability of MMIS with SSRR pads. Finite element analysis has also been conducted to further show the reduced response of a bridge with the modified MMIS under excitations having frequencies within the corresponding attenuation zone (AZ) as compared to the response of a conventional bridge without MMIS. FE analysis further shows the stress generated on the bridge with MMIS systems are within safe limits. Finally, a generalized procedure has been developed to design bridge columns with the proposed modified MMIS.

• Proceedings of the KIEE Conference
• /
• 1998.07f
• /
• pp.1872-1875
• /
• 1998

In the industrial motor drive system, a shaft torsional vibration is often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. Recently, there are new methods which estimate unknown state variables by using a reduced order observer and feedback these state variables by using a pole placement design method. But there is a trade-off between the fast command following property and the attenuation of disturbances and vibrations in these design methods. In this paper, the vibration suppression control of a two-mass system using a reference model is proposed. Because of using a reference model, the proposed control satisfy the fast command following property and the attenuation of disturbances and vibrations. Control parameter can be changed to maintain high system performance in control using a reference model. Experimental results show the validity of the proposed state feedback control using a reference model, and this controller is compared with the state feedback controller.