• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.1
• /
• pp.43-48
• /
• 2013

In this paper, magnetic buoyancy force on nonmagnetic solid object submerged in magnetic liquid was simulated and measured. For the evaluation of the force, a multi-physics approach of hydrostatic equilibrium considering magnetic body force as well as gravity is presented. The magnetic body force should be regarded as an additional forcing term in the momentum equation of hydrodynamics. It is also shown that the virtual air-gap based Kelvin's force formula is a useful method for the calculation of force distribution in the magnetic liquid. The experimental result which was performed by a load-cell measurement system agreed quantitatively well with the numerical one.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.664-667
• /
• 2009

We would like to show a measuring technique of azimuthal anchoring energy of the nematic liquid crystals. The electro-optical setup of liquid crystal cell, crossed polarizers and magnetic field was assumed. The planar or hybrid alignment cells were prepared. The director in the light entering substrate and the polarization of light was adjusted into parallel to the magnetic field. The director orientation of exit substrate and analyser maintained perpendicular to the magnetic field. As the magnetic field strength is increased, the director deviates from the easy axis and rotates to the field direction. We obtained an equation calculating the change of transmission with the field and measured experimentally the transmission. By comparing the calculating and experimental data, we obtained the azimuthal anchoring strength.

• Nuclear Engineering and Technology
• /
• v.50 no.6
• /
• pp.869-876
• /
• 2018

The force of a direct current (DC) electromagnetic pump used to transport liquid lithium was analyzed to optimize its geometrical and electrical parameters by numerical simulation. In a heavy-ion accelerator, which is being developed in Korea, a liquid lithium film is utilized for its high charge-stripping efficiency for heavy ions of uranium. A DC electromagnetic pump with a flow rate of $6cm^3/s$ and a developed pressure of 1.5 MPa at a temperature of $200^{\circ}C$ was required to circulate the liquid lithium to form liquid lithium films. The current and magnetic flux densities in the flow gap, where a $Sm_2Co_{17}$ permanent magnet was used to generate a magnetic field, were analyzed for the electromagnetic force distribution generated in the pump. The pressure developed by the Lorentz force on the electromagnetic force was calculated by considering the electromotive force and hydraulic pressure drop in the narrow flow channel. The opposite force at the end part due to the magnetic flux density in the opposite direction depended on the pump geometrical parameters such as the pump duct length and width that defines the rectangular channels in the nonhomogeneous distributions of the current and magnetic fields.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.12
• /
• pp.1667-1675
• /
• 2001

Numerical simulations are carried out for the liquid encapsulant Czochralski(LEC) by imposing a magnetic field. The use of a magnetic field to the crystal growth is to suppress melt convection and to improve the homogeneity of the crystal. In the present numerical investigation, we focus on the range of 0-0.3Tesla strength for the axial and cusped magnetic field and the effect of the magnetic field on the melt-crystal interface, flow field and temperature distribution which are the major factors to determine the quality of the single crystal are of particular interest. For both axial and cusped magnetic field, increase of the magnetic field strength causes a more convex interface to the crystal. In general, the flow is weakened by the application of magnetic field so that the shape of the melt-crystal interface and the transport phenomena are affected by the change of the flow and temperature field.

• Journal of the Korean Magnetics Society
• /
• v.22 no.5
• /
• pp.183-187
• /
• 2012

In this paper, fluid movement of magnetic fluid which has free surface is investigated in a container subjected to a horizontal oscillation. Here, the vertical magnetic field is applied from the bottom of this container. The experiment is performed on the magnetic fluid in a rectangular and a cylindrical container and the effects of magnetic force exerted on the magnetic fluid are investigated on the resonance frequency and liquid surface displacement. The increase of magnetic field affects on the maximum resonance point and the liquid surface displacement. In result, it changes the amplitude of the surface wave and the period of sloshing fluid movement.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.22 no.3
• /
• pp.17-22
• /
• 1986

This paper investigates on the performance of liquid magnetic compass measuring the concomitant angle of the directional system by the kind of compass and the coefficiant of viscosity of the liquid of ones in accordance with the turning angular velocity of the compass bowl in artificial horizontal magnetic fields. The obtained results are as follows; 1. The concomitant angle is to be in proportion to the coefficiant of viscosity of the liquid of compass and the turning angular velocity of the compass bowl, but ones is to be in contrary proportion to the magnetic moment of the magnetic needle and the horizontal geomagnetic. 2. The overdevelopment of the concomitant angle keeps on regularly at any optional degree in the turning angular velocity over$\pi$ radian per minute, but varies periodically at 180 degree below 3 $\pi$ radian per minute.

• Nuclear Engineering and Technology
• /
• v.49 no.1
• /
• pp.82-91
• /
• 2017

Liquid alloy systems have a high degree of thermal conductivity, far superior to ordinary nonmetallic liquids and inherent high densities and electrical conductivities. This results in the use of these materials for specific heat conducting and dissipation applications for the nuclear and space sectors. Uniquely, they can be used to conduct heat and electricity between nonmetallic and metallic surfaces. The motion of liquid metals in strong magnetic fields generally induces electric currents, which, while interacting with the magnetic field, produce electromagnetic forces. Electromagnetic pumps exploit the fact that liquid metals are conducting fluids capable of carrying currents, which is a source of electromagnetic fields useful for pumping and diagnostics. The coupling between the electromagnetics and thermo-fluid mechanical phenomena and the determination of its geometry and electrical configuration, gives rise to complex engineering magnetohydrodynamics problems. The development of tools to model, characterize, design, and build liquid metal thermomagnetic systems for space, nuclear, and industrial applications are of primordial importance and represent a cross-cutting technology that can provide unique design and development capabilities as well as a better understanding of the physics behind the magneto-hydrodynamics of liquid metals. First studies for the development of computational tools for the design of liquid metal electromagnetic pumps are discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.4
• /
• pp.237-246
• /
• 2004

The advantages of the Magnetic Fluid Linear Pump(MFLP) is that this device could Pump the non-conductive. non-magnetic liquid such as Insulin or blood because of the segregation structure of the magnetic fluid and pumping liquid. In this device. the sequential currents are needed to Produce pumping forces so that Pumping Forces and Pumping speed mainly depend on the current Patterns. The excessive forces at Pumping moment could cause the medical shock, and weak forces at intermediate moment could cause the back flow or the pumping liquid. So the ripples of the pumping forces need to be reduced for the medical application. In this research, the driving characteristics in the MFLP by operating current is analysed. The change of magnetic fluid surface according to the driving currents could be obtained be magneto-hydrodynamic analysis so that Pumping fortes could be computed by integration of the surface moving to the pumping direction at each moment. The actual MFLP with 13mm diameter was made and tested for experiments. The effects of driving current and frequency on the pumping forces and pumping speed were analyzed and compared with experimental measurements.

• Proceedings of the KSME Conference
• /
• 2001.06e
• /
• pp.142-147
• /
• 2001

Natural convection of a magnetic fluid is different from that of Newtonian fluids because magnetic body force exists in an addition to gravity and buoyancy. In this paper, natural convection of a magnetic fluids(W-40) in a cubic cavity is examined by numerical and experimental method. One side wall was kept at a constant temperature($25^{\circ}C$), and the opposite side wall was also held at a constant but lower temperature($20^{\circ}C$). Under above conditions, various magnitudes of the magnetic fields were applied up. GSMAC scheme is used for a numerical method, and the thermo-sensitive liquid crystal film(R20C5A) is utilized in order to visualize wall-temperature distributions as an experimental method. This study has resulted in the following fact that the natural convection of a magnetic fluids is controlled by the direction and intensity of the magnetic fields.

• Journal of the Korean Magnetic Resonance Society
• /
• v.24 no.2
• /
• pp.47-52
• /
• 2020

Liquid-liquid phase separation (LLPS) of biomolecules, a newly-found phase behavior of molecules in the liquid phase, has shown to its relationship to various biological function and misfolding diseases. Extensive studies have increasingly revealed a general mechanism of LLPS and characterized the liquid droplet; ho wever, intermolecular interactions of proteins and structural states of LLPS-inducing proteins inside of the droplet remain largely unknown. Solution NMR spectroscopy has emerged as a powerful approach as it provides invaluable information on protein intermolecular interactions and structures at the atomic and residue level. We herein comprehensively address useful techniques of solution NMR including the effect of paramagnetic relaxation enhancement for the study on the LLPS and droplet based on recent studies.