• Steel and Composite Structures
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• v.16 no.1
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• pp.77-96
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• 2014

In this paper, magneto-thermo-elastic problem of a thick truncated conical shell immersed in a uniform magnetic field and subjected to internal pressure is investigated. Material properties of the shell including the elastic modulus, magnetic permeability, coefficients of thermal expansion and conduction are assumed to be isotropic and graded through the thickness obeying the simple power law distribution, while the poison's ratio is assumed to be constant. The temperature distribution is assumed to be a function of the thickness direction. Governing equations of the truncated conical shell are derived in terms of components of displacement and thermal fields and discretised with the help of differential quadrature (DQ) method. Results are obtained for different values of power law index of material properties and effects of thermal load on displacement, stress, temperature and magnetic fields are studied. Results of the present method are compared with those of the finite element method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.106-109
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• 2016

The YBaCuO superconducting bulks were prepared by the thermal diffusion process involving the peritectic reaction to investigate the effect on microstructure and superconductivity. All the diffused YBaCuO could be successively separated from superconducting 123 phase by applying the thermal diffusion process. Electromagnetic properties of treated and untreated YBaCuO superconductor were evaluated to investigate the pinning effect. It was confirmed experimentally that a large amount of magnetic flux was trapped in the thermal treated superconducting bulk than that in the untreated one, indicating that the pinning centers of magnetic flux are related closely to the occurrence mechanism of the magnetic effect.

• Smart Structures and Systems
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• v.25 no.6
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• pp.707-717
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• 2020

In this paper, analysis of thermal post-buckling behaviors of sandwich nanobeams with two layers of multi-phase magneto-electro-thermo-elastic (METE) composites have been presented considering geometric imperfection effects. Multi-phase METE material is composed form piezoelectric and piezo-magnetic constituents for which the material properties can be controlled based on the percentages of the constituents. Nonlinear governing equations of sandwich nanobeam are derived based on nonlocal elasticity theory together with classic thin beam model and an analytical solution is provided. It will be shown that post-buckling behaviors of sandwich nanobeam in thermo-electro-magnetic field depend on the constituent's percentages. Buckling temperature of sandwich nanobeam is also affected by nonlocal scale factor, magnetic field intensity and electrical voltage.

• Journal of Magnetics
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• v.6 no.3
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• pp.94-100
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• 2001

Fe-Co-Ni particles with an average size of 45 and 135 nm are characterized in terms of magnetic phase transformation and magnetic properties at room temperature. BCC structure of Fe-Co-Ni spherical particles can be synthesized from Fe-Co-Ni-Al-Cu precursor films by heating at 600-80$0^{\circ}C$ for the phase separation of Fe-Co rich Fe-Co-Ni particles, followed by a post heating at $600^{\circ}C$ for 5 hours. The average size of nanoparticles was directly determined by the thickness of precursor films. Exchange interactive hysteresis was observed for the nano-composite (Fe-Co-Ni)+(Fe-Ni-Al) films resulting from the short exchange interface between ferromagnetic Fe-Co-Ni particles surrounded by almost papramagnetic Ni-Al-Fe matrix. Arraying the isolated Fe-Co-Ni nano-particles in a random arrangement on $Al_2O_3$substrate the particle assembly showed a behavior of dipole interactive ferromagnetic clusters depending on their volume and inter-particle distance.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1901-1907
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• 2018

This paper is a study for accurate iron loss calculation of a cylindrical linear machine for free piston engine. This study presents that it is possible to accurately predict power loss in ferromagnetic laminations under magnetic flux by specially considering the dependence of hysteresis, classical, and excess loss components on the magnetic induction derivative. Significant iron loss in the armature core will not only compromise the machine efficiency, but may also result in excessive heating, which could lead to irreversible deterioration in the machine performance. Thus, correct prediction of power losses under a distorted flux waveform is therefore an important prerequisite to machine design, particularly when dealing with large apparatus where stringent efficiency standards are required. Finally, it will be discussed about the iron loss in various materials of cylindrical linear electric machine by geometric and electrical parameters. It will give elaborate information about the perfect design and design rules of cylindrical linear machine and in parallel tools for the calculation, simulation and design will be available.

• Proceedings of the KIEE Conference
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• summer
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• pp.1043-1045
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• 2004

This paper deals with the core loss calculation of a BLDC motor made of Soft Magnetic Composite material. Since the teeth of motor partially have overhang in axial direction, 3 - dimensional equivalent magnetic circuit network (3D-EMCN) is used as an analytical method to get flux density of each element. The total core loss is calculated with the magnetic flux density and core loss curves of the SMC material. The calculated result is compared with core loss of the motor without overhang in stator teeth.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.327-328
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• 2006

We have demonstrated that textured $Al_2O_3-mullite-SiC$ nanocomposites can be fabricated by slip casting followed by partial oxidation - reaction sintering of mixed suspensions of $Al_2O_3$ and SiC powders in a high magnetic field. The sintered density was changed by the degree of oxidation at 1200C and 1300C. The degree of orientation of alumina in the nanocomposite was examined on the basis of the X-ray diffraction patterns and scanning electron micrographs. It is confirmed that alumina-oriented nanocomposites were fabricated. The three-point bending strength at room temperature was observed for the nanocomposites.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.455-456
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• 2006

We have demonstrated that textured $Al_2O_3-mullite-SiC$ nanocomposites can be fabricated by slip casting followed by partial oxidation. reaction sintering of mixed suspensions of $Al_2O_3$ and SiC powders in a high magnetic field. The sintered density was changed by the degree of oxidation at 1200C and 1300C. The degree of orientation of alumina in the nanocomposite was examined on the basis of the X-ray diffraction patterns and scanning electron micrographs. It is confirmed that aluminaoriented nanocomposites were fabricated. The three-point bending strength at room temperature was observed for the nanocomposites.

• Structural Engineering and Mechanics
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• v.74 no.3
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• pp.425-434
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• 2020

The present paper is concerned at investigating the effect of hydrostatic initial stress, gravity and magnetic field in fiber-reinforced thermoelastic solid, with variable thermal conductivity. The formulation of the problem applied in the context of the three-phase-lag model, Green-Naghdi theory with energy dissipation, as well as coupled theory. The exact expressions of the considered variables by using state-space approaches are obtained. Comparisons are performed in the absence and presence of the magnetic field as well as gravity. Also, a comparison was made in the three theories in the absence and presence of variable thermal conductivity as well as hydrostatic initial stress. The study finds applications in composite engineering, geology, seismology, control system and acoustics, exploration of valuable materials beneath the earth's surface.

• Current Optics and Photonics
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• v.7 no.4
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• pp.463-470
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• 2023

Hydroxygraphene as a kind of functionalized graphene has important applications in composite, photoelectric and biological materials. In the present study, THz and microfluidic technologies were implemented to study the THz transmission characteristics of hydroxygraphene with different concentrations and residence times in magnetic and electric fields. The results show that the THz transmission intensity decreases with the increase in sample concentration and duration of an applied electric field, while it increases by staying longer in the magnetic field. The phenomenon is analyzed and explained in terms of hydrogen bond, conductivity and scattering characteristics. The results establish a foundation for future research on the THz absorption characteristics of liquid graphene based on microfluidic technology in different external environments. It also provides technical support for the application and development of graphene in THz devices.