• Proceedings of the KSME Conference
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• 2007.05a
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• pp.974-978
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• 2007

In this paper, the requirements of passive levitation for nonmagnetic body in magnetic fluid are investigated. The passive levitation system includes the electromagnetic system composed of two hollow solenoids, the magnetic fluid and the nonmagnetic body made of aluminum. The hollow solenoids generate nonuniform magnetic fields, leading to the gradient of the magnetic field in magnetic fluid. Hence, the resultant magnetic body force in magnetic fluid is used to levitate the nonmagnetic body in the opposite direction of the gravitation. The levitation conditions according to applied current and the mass of the nonmagnetic body are obtained analytically.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.200-202
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• 2003

In this paper, Gauss filter function is used to filter the N-S equation and the subgrid-scale Reynold stresses model is introduced to deduce the practical form of LES equation for 2-D case for flow calculation of hydraulic machine. Then the LES equation and its discrete form in computational field are obtained in the body-fitted coordinate system and the numerical calculation program is built. The incompressible turbulent flow in double-flow-conduits-sewage pump impeller is computed by using the abovementioned program, and then the distribution rules of velocity and pressure in flow field are obtained. Based on this, the designs of double-flow-conduits-sewage pump impeller are optimized.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.9
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• pp.439-453
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• 2001

This study deals with the free vibration of two identical circular plates coupled with a bounded fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. In the theory, it is assumed that the ideal fluid in a rigid cylindrical container and the two plates are clamped along the plate edges. The proposed method is verified by the finite element analysis using commercial program with a good accuracy. Two transverse vibration modes, namely in-phase and out-of-phase, are observed alternately in the fluid-coupled system when the number of nodal circles increases for the fixed nodal diameter. The effect of gap between the plates on the fluid-coupled natural frequencies sis also investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1049-1056
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• 2012

The forced vibration response characteristics of a cracked pipe conveying fluid with a concentrated mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effects of concentrated mass and fluid velocity on the forced vibration characteristics of a cracked pipe conveying fluid are studied. The deflection response is the mid-span deflection of a cracked pipe conveying fluid. As fluid velocity and crack depth are increased, the resonance frequency of the system is decreased. This study will contribute to the decision of optimum fluid velocity and crack detection for the valve-pipe systems.

• Geomechanics and Engineering
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• v.5 no.4
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• pp.283-297
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• 2013

The aim of this paper is to investigate how the soil-structure interaction affects sloshing response of the elevated tanks. For this purpose, the elevated tanks with two different types of supporting systems which are built on six different soil profiles are analyzed for both embedded and surface foundation cases. Thus, considering these six different profiles described in well-known earthquake codes as supporting medium, a series of transient analysis have been performed to assess the effect of both fluid sloshing and soil-structure interaction (SSI). Fluid-Elevated Tank-Soil/Foundation systems are modeled with the finite element (FE) technique. In these models fluid-structure interaction is taken into account by implementing Lagrangian fluid FE approximation into the general purpose structural analysis computer code ANSYS. A 3-D FE model with viscous boundary is used in the analyses of elevated tanks-soil/foundation interaction. Formed models are analyzed for embedment and no embedment cases. Finally results from analyses showed that the soil-structure interaction and the structural properties of supporting system for the elevated tanks affected the sloshing response of the fluid inside the vessel.

• Tribology and Lubricants
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• v.38 no.3
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• pp.109-114
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• 2022

This paper reports the development of an oil flushing system combined with a microbubble generator. Oil flushing plays a crucial role in regulating the lubricant's performance during the lubricant replacement process. Moreover, harmful contaminants, such as sludge, wear particles, and rust, from piping systems or lubrication system can be removed by oil flushing. Oil flushing aims to increase the system's efficiency using a dedicated flushing oil, increasing of the supply pressure and generating a vortex. In addition, it helps the mechanical system or equipment achieve peak performance and reduces the potential for premature failure. However, the contaminant-removal applications of existing oil flushing system are limited. In this research, we aim to improve the performance of oil flushing system by incorporating a microbubble generator, which uses the venture effect to generate microbubbles and mixes them with lubricant. The microbubbles in the blended lubricant remove contaminants from the lubrication system more effectively. Structural mechanics and fluid dynamics are analyzed through fluid-structure interaction (FSI) analysis, and the numerical analysis results are used for the designing the system. The magnitude of the maximum stress is investigated based on the pressure results obtained by the CFD analysis; through the CFD analysis, the mixing ratio of air (bubble) and lubricant is evaluated using the volume of fluid (VOF) model according to the working conditions.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.499-502
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• 2004

The temperature distribution of a glass plate heated in the infrared heating chamber has been investigated. Temperature of the glass panel is measured using a set of thermocouples and the optical pyrometer. Temperatures measured by thermocouples have good agreement with those by the pyrometer. The temperature uniformity of the panel is improved with wall reflectivity, which is one of the important factors to uniformly heat the panel

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.121-122
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• 2008

In this paper, computational analysis on the steady-state and transient behaviors of the valve system is discussed. Fluid-structure interaction (FSI) is taken into account using ADINA software. The computational results are experimentally validated.

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.196-196
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• 2004

• Research in Mathematical Education
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• v.4 no.2
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• pp.57-62
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• 2000

we motivate the of the velocity field of a fluid in three ways: from a calculation of the velocity of a rotating fluid relative to a coordinate system rotating with the fluid and from two calculations of a vector form of circulation in small circles or spheres suspended in a moving fluid.