• BMB Reports
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• v.31 no.3
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• pp.264-268
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• 1998

Dopamine (DA) acts on swimming motor neurons (SMNs) of Polyorchis penicillatus as an inhibitory neurotransmitter by hyperpolarizing their membrane potentials, which results from the activation of voltagesensitive potassium channels mediated through a $D_2-type$ receptor. In addition, DA, and not the hyperpolarized membrane potential, directly decreased the input resistance of SMNs by ca. 50% from 1.42 to 0.68 $G{\Omega}$. It strongly indicates that DA can shunt other excitatory synaptic signals onto SMNs where DA usually elicited much greater responses in their neurites than soma. All these evidences suggest that DA may operate in this primitive nervous system in dual modes as an inhibitory neurotransmitter and neuromodulator as well.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.82-87
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• 2000

The component mode synthesis method(CMS) used for vibration analysis has demerit that error becomes larger, as degree of natural frequency grows higher. The reason of error occurrence is that Guyan's static reduction is used and the number of modes taken in each component is deficient. This paper proposes the substructure synthesis method using dynamic reduction to solve the problem from the component mode synthesis method. Computer simulation for the proposed method. FEM and the component mode synthesis method(CMS) on a rectrangular plate has been carried out to prove the avilability of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.177-183
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• 1996

By utilizing the concept of normal modes, nonlinear dynamics is studied on pendulum dynamic absorber. When the spring mode loses the stability in undamped free system, a dynamic two-well potential is formed in Poincare map. A procedure is formulated to compute the forced responses associated with bifurcating mode and predict double saddle-loop phenomenon. It is found that quasiperiodic motion and stable periodic motion coexist in some parameter ranges, and only periodic motions or rotation of pendulum with chaotic fluctuation are observed in other ranges.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.708-713
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• 2007

Finite element model updating has been performed using an optimization technique in the paper. The objective function consists of natural frequencies, modal assurance criterion values, and bandwidths of modes, which are obtained from finite element analysis and experiment. Young's modulus and damping coefficient of the material are selected as design variables whose values are modified to make the objective function as small as possible. To consider the loading effect of an accelerometer, its mass and moment of inertia are added to design variables. This model updating method has been applied to a cantilever beam, and experimental data are measured by modal test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1293-1296
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• 2007

In this paper, present a finite element method to reduce vibration of a cylindrical structure by avoiding resonance between motor and structure. To analysis the modes of structure, some different FE models (different places and combinations of ribs) of the structure with free-free condition were built and compared.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.865-868
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• 2006

In this paper, a dynamic behavior(natural frequency) of a cracked simply supported pipe conveying fluid is presented. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid due to the coupled mode (modes combined) is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The stiffness of the spring depends on the crack severity and the geometry of the cracked section. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. This study will contribute to the safety test and stability estimation of structures of a cracked pipe conveying fluid.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.930-936
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• 2008

Fluid loading of a vibrating cylindrical shell has influence on natural frequencies and vibration magnitudes of the shell and the acoustic pressure of fluid. The vibroacoustics of fluid-filled cylindrical shells need the coupled solution of Helmholtz equation and governing equation of a cylindrical shell with boundary conditions. This paper proposed the wall impedance of fluid-filled axisymmetric cylindrical shells, focusing on the inner fluid/shell interaction. To propose the impedance, shell displacements used the linear combination of in vacuo shell modes. Acoustic pressure prediction of fluid used Kirchhoff-Helmholtz integral equation with Green's function of the plane mode. For the demonstration of the proposed results, numerical applications on mufflers were conducted.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1590-1594
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• 2007

This paper describes a case study on dynamic characteristics analysis of a 5-axis multi-tasking machine tool of ram-head typed. Natural frequency and corresponding vibration modes of the machine tool structure were obtained by using both FEM modal analysis and an experimental modal test(impulse hammer test). Both the theoretical and experiment analysis results showed good agreement with each other. Finally, some discussion and review, from the view point of resonance vibration and/or mode coupled chatter, were made based on the analysis results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.676-681
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• 2002

System Identification is carried out for a full scale five-story builing to design a vibration controller. Dynamic characteristics such as natural frequencies, damping ratios, and modes are obtained from the input/output information by both sine-sweep method and white noise method. The active mass driver installed on the five floor is applied as external loading to move the building and each floor acceleration is measured and processed for the system identification. The identified building will be experimentally investigated again with viscoelastic dampers installed at inter-stories to obtain the response behavior. Corresponding result will be presented soon.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.399-406
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• 2007

Structural vibrations of generator sets with medium speed diesel engine mainly come from the resonance between the excitations of engine and natural modes of system. The countermeasures to reduce the vibration or to avoid the resonance are fairly well known to workers. However these processes which are applied after the completion of system need much time consumption and additional cost. In this paper, the vibration measurement results collected for about 8 years were compiled as Database. Based on the database, the change of vibration was predicted with respect to variation of system such as engine type, generator weight, mount stiffness, and etc. As results of study, this paper presents the anti-vibration design procedures of newly composed generator sets using Database in the initial design stage and their effects.