• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1988-1991
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• 2005

A micro fluid actuator driven by electromagnetic force at MEMS(Micro Electro Mechanical System) level has been designed. The operation of the actuator was simulated in three steps. First, fluid flow analysis has been performed to determine the actuator load. With the load, dynamic behavior of the actuator structure has been analysed. Finally, fluid-structure interaction analysis has been performed to predict the performance of the actuator. To avoid excessive amount of computation, axisymmetric and plane strain 2-D models were used.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.101-107
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• 2003

Dynamic behavior of flexible rectangular liquid storage structures is analysed by the developed method. The rectangular liquid storage structures are assumed to be fixed to the ground and a moving coordinate system is used. The irrotational motion of invicid and incompressible ideal fluid is represented by two analytic solutions. One is the solution of the fluid motion in the rigid rectangular liquid storage structure due to ground motions and the other is the solution of the fluid motion by the motion of the wall in the flexible rectangular liquid storage structure. The motion of structure is modeled by finite elements. The fluid-structure interaction effect is reflected into the coupled equation of motion as added fluid mass matrix. The free surface sloshing motion and hydrodynamic pressure acting on the wall in the flexible rectangular liquid storage structure due to the horizontal ground motion are obtained by the developed method and verified.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.12 s.189
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• pp.64-71
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• 2006

In this study, to design aluminum scrap recycling equipment, fluid flow and thermal analysis considering electromagnetic phenomenon were carried out by using ANSYS program. The magnetic flux generated by electromagnetic pump has influence on fluid velocity of Al liquid metal with molten metal motion and thermal generation. To investigate the effect of the number of phase on fluid flow and thermal generation, electromagnetic force and magnetic flux were obtained by computer simulation. In addition, the results obtained by fluid flow and thermal analysis, recycling equipment of aluminum scrap with the cooling technology of electromagnetic coil, the most suitable phase and current were proposed.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.4
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• pp.97-109
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• 1998

In this paper, we propose a new approach to solve stochastic fluid flow models applied to the analysis of ceil loss of an ATM multiplexer. Existing stochastic fluid flow models have been analyzed by using linear differential equations. In case of large state space, however. analyzing stochastic fluid flow model without numerical errors is not easy. To avoid this numerical errors and to analyze stochastic fluid flow model with large state space. we develope a new computational algorithm. Instead of solving differential equations directly, this approach uses iterative and numerical method without calculating eigenvalues. eigenvectors and boundary coefficients. As a result, approximate solutions and upper and lower bounds are obtained. This approach can be applied to stochastic fluid flow model having general Markov chain structure as well as to the superposition of heterogeneous ON-OFF sources it can be extended to Markov process having non-exponential sojourn times.

• Journal of Korean Neurosurgical Society
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• v.53 no.1
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• pp.59-61
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• 2013

Authors report a rare case of acute intracranial subdural and intraventricular hemorrhage that were caused by intracranial hypotension resulted from cerebrospinal fluid leakage through an unidentified dural tear site during spinal surgery. The initial brain computed tomography image showed acute hemorrhages combined with preexisting asymptomatic chronic subdural hemorrhage. One burr hole was made over the right parietal skull to drain intracranial hemorrhages and subsequent drainage of cerebrospinal fluid induced by closure of the durotomy site. Among various methods to treat cerebrospinal fluid leakage through unidentified dural injury site, primary repair and spinal subarachnoid drainage are well known treatment options. The brain imaging study to diagnose intracranial hemorrhage should be taken before selecting the treatment method, especially for spinal subarachnoid drainage. Similar mechanism to its spinal counterpart, cranial cerebrospinal fluid drainage has not been mentioned in previous article and could be another treatment option to seal off an unidentified dural tear in particular case of drainage of intracranial hemorrhage is needed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.101-105
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• 2008

A flexible structure submerged in acoustic fluid is affected by its surrounding fluid. In transient response of a submerged structure, the coupled effect between structures and surrounding fluid emerges as damping and added mass at early and late time, respectively. Therefore, the characteristics of submerged structure such as natural frequencies and damping coefficients are changed by its surrounding fluid. In this paper, the analytic modal equation of a spherical shell surrounded by water and air is dealt with. Through the example, the damping coefficients and natural frequencies of flexible structures are studied for various external acoustic fluid and structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.160-165
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• 2008

Fluid loading of a vibrating cylindrical shell can change natural frequencies and vibration magnitudes of the shell and a vibrating cylindrical shell can also change 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 Kirchchoff-Helmholtz Integral equation with Green function of the plane mode. For the demonstration of the proposed results, numerical applications on mufflers were conducted.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.1
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• pp.57-63
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• 2009

Magneto-Rheological(MR) fluid composes of a base fluid and ferromagnetic particles less than tens of micrometer size dispersed in the fluid. It is called as a smart material because its rheological properties are changable by a magnetic field. Its important applications are active devices such as controllable dampers and controllable clutches. The merit of those products is that their functional characteristics are controllable such that they enable active control strategies. This paper proposes an idea for machine tool applications of the MR fluid clutch as a safety device for power transmission. FEM has been used for magnetic field analyses and the results are compared with some former experiments. Some design syntheses of the MR clutches are suggested and hopefully considered that it may be an effective safety device for power transmission of machine tools.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.66-71
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• 2001

In this work, an ER clutch has been constructed and its characteristics have been evaluated by adapting an electro-rheological fluid(ERF) as an operating medium. ER fluids are suspensions which show an abrupt increase in rheological properties under electric fields. An ER clutch system using ER fluid is a new conception device because an apparent viscosity of ER fluid can be changed by apply an electric field. As a first, Bingham properties of ER fluids are experimentally distilled as a function of electric field. We use the disk type ER clutch in which the ER fluid fills the annular space between a pair of coaxial disk electrodes and experiment results show that the measured revolution per minute was increased with the increase of the electric field. The ER fluid used in the present study consists of weight fraction 35% in zeolite suspended silicone oil.