• Korean Journal of Materials Research
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• v.11 no.6
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• pp.512-518
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• 2001

It has been well known that 6.5wt% Si steel sheets have excellent magnetic properties such as low core loss. high maximum permeability and low magnetostriction. In this work, we studied a method for producing 6.5wt% Si steel sheets using a chemical vapor deposition (CVD) method. The following is the procedure adopted in this work to produce 6.5wt% Si steel sheets; SiCl$_4$ gas is applied onto a low content-Si steel sheet placed in a tube furnace. Silicon atoms resulted from the decomposition of SiCl$_4$ are permeated through the surface of the steel sheet. Finally, by the diffusion process maintaining it under a high temperature the silicon atoms diffuse uniformly into the sheet. Through this process, 6.5wt% Si steel sheets can be obtained. The manufactured Fe-6.5wt% Si steel sheet with a thickness of 0.5mm exhibited a high frequency core loss (W$_{2}$1k/) of 8.92 W/kg. Its permeability increased from 37,100 to 53,300 at 1 tesular(T). The mechanical properties of the manufactured steel sheets were also estimated and the result showed that the workability was significantly improved by annealing in vacuum at 773k. Increased plastic deformation was also observed prior to fracture and the amount of grain boundary rupture was reduced.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.185-191
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• 1998

Magnetic domain structure and static magnetic properties were investigated in the ultra thin 3%Si-Fe strip wound cores when the strips were wound and annealed to relief the stress. The elastic and plastic deformation due to the radius of curvature was also investigated for the cores. At the as-wound state, the maze pattern domain structure was generated on the concave surface of the core and 180$^{\circ}$ domain wall was recovered by annealing 600 $^{\circ}C$$\times$30 min. After annealed by 900 $^{\circ}C$$\times$30 min, Hc of strip-wound cores was not reached to the $H_c$ of the strip even at the cores of elastic deformation region. It is necessary to relief the local stress remained in the core when the cores were manufactured for the application of ultra-thin 3%Si-Fe strip.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.296-301
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• 2016

Using high magnetic flux from a 60 Hz high-current cable, a 2 W wireless-powered energy harvesting receiver for sensor operation, internet of things (IoT) devices, and LED lights inside electrical cable tunnels is proposed. The proposed receiver comprises a copper coil with a high number of turns, a ring-shaped ferromagnetic core, a capacitor for compensating for the impedance of the coil in series, and a rectifier with various types of loads, such as sensors, IoT devices, and LEDs. To achieve safe and easy installation around the power cable, the proposed ring-shaped receiver is designed to easily open or close using a clothespin-shaped handle, which is made of highly-insulated plastic. Laminated silicon steel plates are assembled and used as the core because of their mechanical robustness and high saturation flux density characteristic, in which the thickness of each isolated plate is 0.3 mm. The series-connected resonant capacitor, which is appropriate for low-voltage applications, is used together with the proposed receiver coil. The concept of the figure of merit, which is the product weight and cost of both the silicon steel plate and the copper wire, is used for an optimized design; therefore, the weight of the fabricated receiver and the price of raw material is 750 gf and USD $2 each, respectively. The 2.2 W powering capability of the fabricated receiver was experimentally verified with a power cable current of $100A_{rms}$ at 60Hz.

• Korean Journal of Heritage: History & Science
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• v.50 no.4
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• pp.122-147
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• 2017

The Jungsandong sites are distributed across quartz and mica schist formations in Precambrian, and weathering layers include large amounts of non-plastic minerals such as mica, quartz, felspar, amphibole, chlorite and so on, which form the ground of the site. Neolithic pottery from Jungsandong exhibits various brown colors, and black core is developed along the inner part for some samples, and sharp comb-pattern and hand pressure marks can be observed. Their non-plastic particles have various composition, size distribution, sorting and roundness, so they are classified into four types by their characteristic mineral compositions. I-type (feldspar pottery) is including feldspar as the pain component or mica and quartz. II-type (mica pottery) is the combination of chloritized mica, talc, tremolite and diopside. III-type (talc pottery) is with a very small amount of quartz and mica. IV-type (asbestos pottery) is containing tremolite and a very small amount of talc. The inner and outer colors of Jungsandong pottery are somewhat heterogeneous. I-type pottery group shows differences in red and yellow degree, depending on the content of feldspar, and is similar to III-type pottery. II-type is similar to IV-type, because its red degree is somewhat high. The soil of the site is higher in red and yellow degree than pottery from it. The magnetic susceptibility has very wide range of 0.088 to 7.360(${\times}10^{-3}$ SI unit), but is differentiated according to minerals, main components in each type. The ranges of bulk density and absorption ratio of pottery seem to be 1.6 to 1.7 and 13.1 to 26.0%, respectively. Each type of pottery shows distinct section difference, as porosity and absorption ratio increase in the order as follows: I-type (organic matter fixed sample) < III-type and IV-type < I-type < II-type (including IV-type of IJP-15). The reason is that differences in physical property occur according to kind and size of non-plastic particles. Although Jungsandong pottery consists of mixtures of various materials, the site pottery has a geological condition on which all mineral composition of Jungsandong pottery can be provided. There, it is thought that raw materials can be supplied from weathered zone of quartz and mica schist, around the site. However, different constituent minerals, size and rock fragments are shown, suggesting the possibility that there can be more raw material pits. Thus, it is estimated that there may be difference in clay and weathering degree.