• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.223-226
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• 2000

Currently a multichannel system for virtual 3-D sound rendering is under development. Robust sound image formation and smooth real time interactivity are main design Points. The system utilizes VBAP algorithm as virtual sound image positioning. Overall system settings can be easily configured. We developed software, RIMA. as a driving Program of the system. At this stage, it is possible to position virtual sound images at arbitrary positions in three-dimensional space. The characteristics of the system are discussed. The system has been applied to the KAIST Bicycle Simulator to generate the virtual sound field.

• Journal of Ocean Engineering and Technology
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• v.31 no.5
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• pp.364-370
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• 2017

A numerical model based on the mode superposition method is used to study the vortex-induced vibration response characteristics of a deep-sea riser such as steel catenary riser (SCR). A steel catenary riser can be modeled using a flexible cable with simple supports at both ends. The natural frequency, mode shape and mode curvature of the riser are calculated and the vortex-induced vibration response of the riser is obtained using the equilibrium of the input and output power. The mode superposition method is applied to the vibrational stresses for each mode to calculate the overall riser fatigue life.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.80-85
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• 1996

Predictions of vibration induced by subway operation has been studied through comparison between the measurement values and the estimated values which proposed by other scientists to determine the adequacy of each equation. It was found from this study that the Wilson's prediction equation gives the best overall approximation value although the peak frequency band lies somewhat higher than that obtained from measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1247-1252
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• 2007

The machine equipment of the building inside occurs the vibration. In order to reduce this vibration spring, rubber pad is used. But efficiency of this classical mount is restricted at specific frequency. Also maximum efficiency design is complicated. This paper proposes and examines a attached mass isolation system that is used to reduce transmitted vibrations from machines onto their floor support. With attached mass the low frequency performance is improved overall. The performance is showed in 2 degree of freedom model test. And the proposed isolator has been validated by dynamic test and good agreement between theoretical and experimental results has been obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.851-856
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• 2016

In this paper, the free vibration characteristics of longitudinally corrugated cylindrical shells is investigated by the theoretical analysis. The equivalent homogenization model is adapted to investigate the overall mechanical behavior of these corrugated shells. The corrugated element can be represented as an orthotropic material. Both the effective extensional and flexural stiffness of this equivalent orthotropic material are considered in the analysis. To demonstrate the validity of the proposed theoretical approach, the theoretical results are compared with those from 3D finite element analysis using ANSYS commercial code. Some numerical results are presented to check the effect of the geometric properties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.351.2-351
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• 2002

The overall noise reduction was compared in regard to the vibrational characteristics of floor impact noise in a multi story residential building which has several noise reduction treatments. The vibration through its structural elements such as wall, floor and ceiling and sound emitting were investigated for each insulation treatment. It was found that, in case of heavy-weight impact noise, the vibration energy is emitted mostly from ceiling, but for the light-weight impact noise, most of the energy comes through ceiling and walls. (omitted)

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.697-703
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• 2000

In design step of an active vibration control system, the stability analysis is required for obtaining a stable control region so that the system is protected from it violent natural vibration. This paper describes the procedure of stability simulation for the active magnetic bearing-main spindle of a machine tool. The characteristic equation of the overall system is derived by assembling the dynamic equation of a flexible shaft and the transfer functions of feedback components. And the stable region is obtained by calculating the eigenvalues of the characteristic equation. The simulated control stable region is good agreement by comparing the experiment. Therefore the stable control gain is selected in this paper.

• Structural Engineering and Mechanics
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• v.22 no.1
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• pp.53-70
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• 2006

The paper summarizes the dynamic-based assessment of a reinforced concrete arch bridge, dating back to the 50's. The outlined approach is based on ambient vibration testing, output-only modal identification and updating of the uncertain structural parameters of a finite element model. The Peak Picking and the Enhanced Frequency Domain Decomposition techniques were used to extract the modal parameters from ambient vibration data and a very good agreement in both identified frequencies and mode shapes has been found between the two techniques. In the theoretical study, vibration modes were determined using a 3D Finite Element model of the bridge and the information obtained from the field tests combined with a classic system identification technique provided a linear elastic updated model, accurately fitting the modal parameters of the bridge in its present condition. Hence, the use of output-only modal identification techniques and updating procedures provided a model that could be used to evaluate the overall safety of the tested bridge under the service loads.

• Advances in nano research
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• v.15 no.2
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• pp.141-153
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• 2023

The main objective of this paper is to develop the finite element study on the nonlinear free vibration of functionally graded nanocomposite spherical shells reinforced with graphene platelets under the first-order shear deformation shell theory and von Kármán nonlinear kinematic relations. The governing equations are presented by introducing the full asymmetric nonlinear strain-displacement relations followed by the constitutive relations and energy functional. The extended Halpin-Tsai model is utilized to specify the overall Young's modulus of the nanocomposite. Then, the finite element formulation is derived and the quadrilateral 8-node shell element is implemented for finite element discretization. The nonlinear sets of dynamic equations are solved by the use of the harmonic balance technique and iterative method to find the nonlinear frequency response. Several numerical examples are represented to highlight the impact of involved factors on the large-amplitude vibration responses of nanocomposite spherical shells. One of the main findings is that for some geometrical and material parameters, the fundamental vibrational mode shape is asymmetric and the axisymmetric formulation cannot be appropriately employed to model the nonlinear dynamic behavior of nanocomposite spherical shells.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.450-453
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• 2006

Coupling adjacent building with supplemental damping devices is a developing method of reduced structural response due to wind and seismic excitations. The philosophy is to allow structures, vibrating at different frequencies, to exert control forces upon one another to reduce the overall responses of the system. This paper studies the effect of installing vibration control devices of two high rise building structures(49 stories and 42 stories) connected by sky-bridge. According to the analysis results the use of sky-bridge can be effective in increasing damping ratio of the system.