• Journal of computational fluids engineering
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• v.10 no.1
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• pp.56-62
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• 2005

Large eddy simulation of vortexing flow of molten steel in the continuous casting mold with and without DC magnetic field was conducted. The influence of the position of magnetic field to the residence time and depth of the vortex was analyzed. The mechanism of the influence of magnetic field to the vortexing flow was found. The computational results show that the vortexing flow is the result of shearing of the two un-symmetric surface flows from the mold narrow faces when they meet adjacent to the SEN; the un-symmetric flow for turbulent vortex is caused by turbulent energy of the fluid and that for biased vortex is caused by biased flow and the turbulent energy of fluid; with the moving of the magnetic field from the centerline of the outlet of the SEN to the free surface, the surface velocity is decreased gradually and the depth of the turbulent vortex and the biased vortex is decreased, the residence time is increased with the magnetic field moves from DL=120mm to DL=60mm and then decreased; the turbulent vortex and the biased vortex can be eliminated when the magnetic field is located at the free surface.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.160-160
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• 2003

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.33.4-33.4
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• 2008

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.234-235
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• 2003

• Proceedings of the Korean Magnestics Society Conference
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• 2001.04a
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• pp.84-85
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• 2001

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.173-178
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• 1994

The water-based magnetic fluids were prepared with the synthesized ultra-fine magnetite, oleic acid and SDBS (sodium dodecyl benzene sulfonate) as surfactants. The dispersion of water-based magnetic fluids was about 90 % when the added amounts of oleic acid and SDBS for magnetite(27 g) were more than $2.66{\times}10^{-3}$ mol and 10 g respectively. As the solid content increased from o. 05 g/cc to 0.4 g/cc, saturation magnetization of magnetic fluids at 5 kOe increased from 1.98 emu/g to 9.63 emu/g at $Fe^{2+}/Fe^{3+}=0.5$ and from 2.7 emu/g to 14.63 emu/g at $Fe^{2+}/Fe^{3+}=1.0$, and the its viscosity increased from 1.3 cp to 4.4 cp at $Fe^{2+}/Fe^{3+}=0.5$. pH region of oleic acid and SDBS stabilized water-based mag¬netic fluids was stable was in the range of pH 3.0 to pH 11.0. Stability of Water-based magnetic fluids can be obtained by observation of magnetic memory patterns on the VCR tape.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.120-120
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• 2004

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.235-244
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• 2012

Nuclear magnetic resonance (NMR) logging has been considered one of the most complicated nevertheless, one of the most powerful logging methods for the characterization on of both rocks and natural fluids in formation. NMR measures magnetized signals (polarization and relaxation) between the properties of hydrogen nucleus called magnetic moment and applied magnetic fields. The measured data set contains two important petrophysical properties such as density of hydrogen in the fluids inside the pore space and the distinct decay rate for fluid type. Therefore, after the proper data processing, key petrophysical information, not only the quantities and properties of fluids but also supplies of rock characterization in a porous medium, could be archived. Thus, based on this information, several ongoing researches are being developed in estimating aspects of reservoir productivity information, permeability and wettability since it is the key to having correct interpretation. This study goes through the basic theory of NMR at first, and then reviews NMR logging tools as well as their technical characteristics. This paper also briefly discusses the basic knowledge of NMR simulation algorithm by using Random walk.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.286.1-286.1
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• 2007

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2962-2964
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• 2005

Magneto-Rheological (MR) fluid is suspension of fine magnetic particles in a liquid carrier such as silicon oil or water. MR fluid exhibits solid-like mechanical behavior into chain or clusters with high yield stress when magnetic field is applied to the particles. The response of MR fluids is very quick and reversible after removal of the field. MR Fluids have high yield stress (up to 5kPs) and operate in low voltage power supply. Recently, MR damper using MR fluids was open used in vibration control system such as structural devices, seat vibration controllers and helicopter rotor systems, but it is too big in size and heavy. Therefore, it is not appreciate to rehabilitation devices such as prosthetic limbs.