• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.146-147
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• 2002

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.379-380
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• 2000

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1457-1461
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• 2013

The $Fe_3O_4$-core and Ag-shell ($Fe_3O_4@Ag$ nanoeggs) were prepared through the encapsulation of 3-aminopropyltriethoxysilane-coated magnetite nanoparticle in nano-Ag shell by a simple chemically controlled procedure. The $Fe_3O_4@Ag$ nanoeggs were characterized by scanning electron microscopy, transmission electron microscopy, UV-vis spectrum and superconducting quantum interference device magnetometer, respectively. A detailed analysis is provided of how the hydrolysis and condensation of 3-aminopropyltriethoxysilane and the pH value are vital in fabricating the $Fe_3O_4@Ag$ nanoeggs. The prepared $Fe_3O_4@Ag$ nanoeggs possessed uniform size, improved monodispersity, stability against aggregation and high magnetization, which were utilized for the detection of latent fingerprints deposited onto different surfaces. The experimental results showed that the latent fingerprints developed with the $Fe_3O_4@Ag$ nanoeggs powders exhibited excellent ridge details with minimal background staining.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.343-350
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• 1995

An overview will be given on recent Mossbauer and magnetization investigation of the applied field dependence of the magnetic properties of typical systems without strong magnetic anisotropy and showing the absence of magnetic saturation in high fields (including iron-rich spin glass (amorphous $Fe_{93}Zr_{7}$, soft ferromagnets (amorphous $Fe_{88}Zr_{12}$, $Fe_{70}Ni_{20}Zr_{10}$ and $Fe_{88}B_{12}$) and pure Fe). The results emphasize that shape anisotropy due to surface irregularities causes misalignment between the magnetization and the applied field in the otherwise collinear magnetic structure.

• Steel and Composite Structures
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• v.20 no.6
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• pp.1323-1343
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• 2016

This paper presents the results of an extensive numerical analysis program devoted to the investigation of the mechanical behaviour of bolted ball-cylinder joints. The analysis program is developed by means of finite element (FE) models implemented in the non-linear code ABAQUS. The FE models have been accurately calibrated on the basis of available experimental results. It is indicated that the FE models could be used effectively to describe the mechanical performance of bolted ball-cylinder joints, including failure modes, stress distributions and load-displacement curves. Therefore, the proposed FE models could be regarded as an efficient and accurate tool to investigate the mechanical behavior of bolted ball-cylinder joints. In addition, to develop a further investigation, parametric studies were performed, varying the dimensions of hollow cylinders, rectangular tubes, convex washers and ribbed stiffener. It is found that the dimensions of hollow cylinders, rectangular tubes and ribbed stiffener influenced the mechanical behaviour of bolted ball-cylinder joints significantly. On the contrary, the effects of the dimensions of convex washers were negligible.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.687-689
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• 1995

Our team works on mixture of hard magnetic materials. As hard magnetic material we used mixture of powders: melt-spun ribbon Nd-Fe-B, ferrite and Alnico. Their different mixtures are basic material for dielectromagnets under our investigation. Main disadvantage of dielectromagnets with Nd-Fe-B alloy powder as a component is a low corrosion resistance. Protection against corrosion is covering dielectromagnets with metallic or organic coating film. The coating film protects dielectromagnets from free particles on the surface and low resistance for mechanical stresses too. The surface of dielectromagnets prepared from mixture of powders if formed by metallic particles - powder of Nd-Fe-B and Alnico, particles of oxide - powder of ferrite and particles of resin - bonding materials. Team work on technology of laying the metallic coating on dielectromagnets prepared from mixture of mentioned powders. Papers show the results of initial investigation on metallic coating technology. It shows influence of type and used technology of the metallic coating film on magnetic properties of dielectromagnets.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.218.2-218.2
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• 2008

• Journal of Korean Vacuum Science & Technology
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• v.6 no.2
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• pp.76-78
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• 2002

We have carried out the first-principle electronic structure calculations to investigate the spacer layer formation of Fe/Si multilayered films (MLF) and compared with the results obtained by optical spectroscopy. The computer-simulated spectra based on various structural models of MLF showed that neither FeSi$_2$ nor B2O-phase FeSi, which are semiconducting, could be considered as the spacer layers in the Fe/Si MLF for the strong antiferromagnetic coupling. The optical properties of the spacer extracted from the effective optical response of the MLF strongly support its metallic nature. The optical conductivity spectra of various phases of Fe-Si compounds were calculated and compared with the extracted optical properties of the spacer. From the above theoretical investigations it is concluded that a E2-phase metallic FeSi compound is spontaneously formed at the interfaces during deposition.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.615-619
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• 2012

Recently, ultrafine grained (ufg, typically 100 > d > 500 nm) Ti-Fe eutectic materials have been highlighted due to their extraordinarily high strength and good abrasion resistance compared to conventional coarse grained (cg, d > $1{\mu}m$) materials. However, these materials exhibit limited plastic strain and toughness during room temperature deformation due to highly localized shear strain. Several approaches have been extensively studied to overcome such drawbacks, such as the addition of minor elements (Sn, Nb, Co, etc.). In this paper, we have investigated the influence of the addition of Gd and Y contents (0.3-1.0 at.%) into the binary Ti-Fe eutectic alloy. Gd and Y are chosen due to their immiscibility with Ti. Microstructural investigation reveals that the Gd phase forms in the eutectic matrix and the Gd phase size increases with increasing Gd content. The improvement of the mechanical properties is possibly correlated to the precipitation hardening. On the other hand, in the case of Ti-Fe-Y alloys, with increasing Y contents, primary phases form and lamellar spacing increases compared to the case of the eutectic alloy. Investigation of the mechanical properties reveals that the plasticity of the Ti-Fe-Y alloys is gradually improved, without a reduction of strength. These results suggest that the enhancement of the mechanical properties is closely related to the formation of the primary phase.

• Journal of Korea Foundry Society
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• v.19 no.1
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• pp.71-76
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• 1999

Eutectic and off-eutectic Al-Fe alloys were unidirectionally solidified at the solidification rate of $1{\sim}50\;mm/min$ under the temperature gradients $75{\sim}80^{\circ}C/cm$. The investigation has been carried out for the microstructural variation, phase transition, mechanical properties by means of detailed analyses of stress-strain, micro-Vickers hardness and scanning electron micrography. The thermal stability at elevated temperature has been studied on $Al-Al_6Fe$ eutectic alloy held at $600^{\circ}C$ for $0{\sim}150$ hours. When the solidification rate was less than 10mm/min, the X-ray diffraction and EDS analysis showed the presence of $Al_3Fe$ compound. As the solidification rate more than 20 mm/min, $Al-Al_3Fe$ eutectic phase was transfered into $Al-Al_6Fe$ eutectic phase. The mechanical properties of unidirectionally solidified off-eutectic Al-Fe alloy is better than those of unidirectionally solidified eutecic Al-Fe alloy Maximum ultimate tensile strength was obtained in Al-2.25% Fe alloy which was unidirectionally solidified at the solidification rate of 20 mm/min. The metastable $Al-Al_6Fe$ phase was transferred into stable $Al-Al_3Fe$ phase at $600^{\circ}C$ held for 150 hours.