• Transactions on Electrical and Electronic Materials
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• v.9 no.6
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• pp.265-272
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• 2008

In this paper, AC losses of long wire Bi-2223 tapes with different twist pitch of superconducting core were fabricated, measured and analyzed. These samples produced by a powder-in-tube method are multi-filamentary tape with Ag matrix. Also, it's produced by non-twist. The critical current measurement was carried out under the environment in Liquid nitrogen and in zero field by 4-prob method. And the Magnetic measurement was carried out under the environment of applied time-varying transport current by transport method. From experiment, the susceptibility measurements were conducted while cooling in a magnetic field. Flux loss measurements were conducted as a function of ramping rate, frequency and field direction. The AC flux loss increases as the twist-pitch of the tapes decreased, in agreement with the Norris Equation. Neutron-diffraction measurements have been carried out investigate the crystal structure, magnetic structures, and magnetic phase transitions in Bi-2223([Bi, Pb]:Sr:Ca:Cu:O).

• Textile Coloration and Finishing
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• v.28 no.2
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• pp.118-123
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• 2016

The use of natural organic dyes obtained from renewable resources such as plants and trees has the potential for not only preserving petrochemicals but also all-endangered environment for coming next generations. In spite of inferior fastness, natural dyes can be employed in the colouration of natural as well as synthetic fibers. Recently, the potentiality of using natural dyes in colouration with additional UV-protection and antimicrobial properties has been reported. This study is aimed to investigate the effect of Zinc compounds compared to another metallic compounds as mordants on the dyeing properties of natural dye extracted from mulberry leaves and coffee. In this study, the results showed Zinc compounds was expose that is more similar than other mordants in washing fastness through a repeated experiment. Also, Zinc is the environmental impact is less material compared with other mordants, essential edibility minerals ingredient that is necessary in human body.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1579-1582
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• 2011

Alumina particles wrapped in few-layer graphene sheets were prepared by calcining aluminum nitride powders under a mixed gas flow of carbon monoxide and argon. The graphene sheets were characterized by powder X-ray diffraction (XRD), Raman spectroscopy, electron energy loss spectroscopy, and high-resolution transmission electron microscopy. The few-layer graphene sheets, which wrapped around the alumina particles, did not exhibit any diffraction peaks in the XRD patterns but did show three characteristic bands (D, G, and 2D bands) in the Raman spectra. The dye-sensitized solar cell (DSSC) with the alumina particles wrapped in few-layer graphene sheets exhibited significantly improved overall energy-conversion efficiency, compared to conventional DSSC, due to longer electron lifetime.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.3
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• pp.265-274
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• 2004

To investigate the effect of cereal powders on the quality and storage characteristics of sausage, Aw, pH, microbial count, TBA value, VBN value, textual and sensory characteristics were examined. Water activity tended to decrease as storage time prolonged and all the samples showed higher Aw's than that of the control. During the storage period, pH values of all the samples decreased. L, a and b values had a tendency to decrease during the storage period. During the four weeks storage at 4$^{\circ}C$, TBA and VBN values of all the sample showed increasing tendency and were lower than those of the control. Total plate counts of bacteria, the number of lactic acid bacteria and coliform bacteria counts increased as the storage time prolonged. Texture characteristics of all samples increased up to 1 week storage and decreased subsequently. The sensory scores of all the samples decreased as the storage time prolonged.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.289-294
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• 1995

As the results of the study on the effects of mixing time for raw materials to the electric and magnetic properties of Mg-ferrite, the fraction of spinel phase after calcination and the geometry density of sintered Mg-ferrite increased from 30% to 100% and from 2.5g/cc to 4.25g/cc respectively due to mixing-homobenity of raw materials. The AC resistivity of grains decreased and lattice parameter, saturation magnetization increased due to the increase in Fe+2 of sintered body. conclusively the characteristic of powder after calcination had strong influence on the microstructure, electric, and magnetic properties in Mg-ferrite sintered body.

• Journal of the Korean Ceramic Society
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• v.38 no.4
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• pp.380-387
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• 2001

140$0^{\circ}C$ 환원 분위기(질소-수소) 조건에서 열처리하여 반도성 SrTiO$_3$하소분말을 제조하였다. 하소분말을 이용하여 135$0^{\circ}C$에서 2시간동안 상압 소결하여 소결체를 제조하였으며, 이때 소결 분위기에 따른 소결체 입계의 전기적 특성을 고찰하였다. 이들 소결체는 전형적인 바리스터 특성을 나타내었으며, 특히 소결 분위기를 질소-수소로부터 공기로 변화시킴에 따라서 소결체의 문턱 전압, 입계 비저항 그리고 입계 전위 장벽은 430V/cm, 10MΩ.cm 그리고 2.0$\times$$10^{-3}$eV로부터 1000V/cm 이상, 240 MΩ.m 그리고 1.1eV로 변하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.749-752
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• 2001

Very fine cobalt oxide xerogel and ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. The results materials determine by using electrode that mixed ketjen black and PVdF. But CoO$\_$x/ have the low voltage, so we experimente to change electrolyte and various concentration.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.291-291
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• 1999

Long 19-filamentary Bi-2223 tapes were prepared using the so called "powder-in-tube" method. In the preparation, two types of precursor powders and two different reduction rates during rolling were used. Also two rolling method, which resulted in different filament geometry, were used. The characteristics of the tapes will be presented. Also A coil was prepared using two 56 m-long 19-filament tape. It was consisted of two double pancake coils. Each pancake, which is separated by FRP spacer, was composed of 98 turns. The experimental results will be presented and compared to the simulation result.

• Tribology and Lubricants
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• v.19 no.5
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.14-18
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• 2000

This paper describes a series of experiments to investigate the operational characteristics of a superconducting power supply with superconducting excitation coil. In this experiment, the superconducting excitation coil is introduced to control the pole-flex in the air gap of the machine. The operating current of the superconducting powder supply is designed to have the value of 300 [A] for the rotational speed of 600 rpm. Sensors installed on the Nb sheet yield the information on the spatial and temporal behaviors of the magnetic field in spot and on the characteristics of the superconducting power supply.