• Textile Coloration and Finishing
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• v.32 no.2
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• pp.80-88
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• 2020

Supercritical fluid dyeing is a new alternative to the conventional aqueous process because of its environmental benefits. In this study, dyeing properties of Nylon 6 fabrics were investigated depending on dyeing temperature and pressure in supercritical CO₂ fluid dyeing system. In order to select the optimal condition for supercritical fluid dyeing of Nylon 6 fabrics, dyeing temperature and pressure were varied from 100, 110, 120℃, 200, 230, 260bar, respectively. The results of K/S values and levelling properties showed that the optimal dyeing condition for Nylon 6 fabrics was 110℃ and 230bar in the supercritical CO₂ fluid dyeing system. The washing fastness ratings of the dyed Nylon 6 fabrics under supercritical medium were good for both fading and staining except for staining on nylon.

• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.455-461
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• 2006

High temperature dielectric constants of the various ceramic materials have been measured using cavity perturbation method. The measurements were applied to refractory, traditional and fine ceramic powder compacts from room temperature to $1200^{\circ}C$. Calibration constant in the equation suggested by Hutcheon et al., was determined from the dielectric constants of reference specimen (teflon and alumina) at room temperature. From these results, informations on the refectory materials were obtained for the microwave kiln design and understanding of the microwave heating effects of ceramics have been improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.421-421
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• 2012

Graphene has drawn enormous attention owing to its outstanding properties, such as high charge mobility, excellent transparence and mechanical property. Synthesis of Graphene by chemical vapor deposition (CVD) is an attractive way to produce large-scale Graphene on various substrates. However the fatal limitation of CVD process is high temperature requirement(around $1,000^{\circ}C$), at which many substrates such as Al substrate cannot endure. Therefore, we propose plasma enhanced CVD (PECVD) and decrease the temperature to $400^{\circ}C$. Fig. 1 shows the typical structure of RF-PECVD instrument. The quality of Graphene is affected by several variables. Such as plasma power, distance between substrate and electronic coil, flow rate of source gas and growth time. In this study, we investigate the influence of these factors on Graphene synthesis in vacuum condition. And the results were checked by Raman spectra and conductivity measurement.

• Korean Journal of Materials Research
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• v.25 no.7
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• pp.347-351
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• 2015

To study the characteristics of ZTO, which is made using a target mixed $ZnO:SnO_2=1:1$, the ZnO and $SnO_2$ were analyzed using PL, XRD patterns, and electrical properties. Resulting characteristics were compared with the electrical characteristics of ZnO, $SnO_2$, and ZTO. The electrical characteristics of ZTO were found to improve with increasing of the annealing temperature due to the high degree of crystal structures at high temperature. The crystal structure of $SnO_2$ was also found to increase with increasing temperatures. So, the structure of ZTO was found to be affected by the annealing temperature and the molecules of $SnO_2$; the optical property of ZTO was similar to that of ZnO. Among the ZTO films, ZTO annealed at the highest temperature showed the highest capacitance and Schottky contact.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.116-119
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• 2007

The application of light weight materials, such as aluminum alloy, has been limited due of their poor formability. Especially, aluminum alloy tube has limited expansion capability at most 15% at room temperature. New manufacturing process, called hot air forming, is introduced to apply aluminum tube to the automotive suspension components which have complex shape and require high expansion ratio about 40%. The process is carried out at the elevated temperature above $500^{\circ}C$, so numerous material properties and process parameters related to the high temperature should be investigated and determined to get a sound product. In this study, the effect of thermal properties and forming parameters such as the temperature of tool, axial feeding and gas pressure are analyzed by using explicit finite element method.

• Laser Solutions
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• v.12 no.4
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• pp.12-16
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• 2009

The engineering ceramic is one of the materials advantageous in various conditions with high strength, endurance at high temperature, abrasion resistance and corrosion resistance, etc. However, due to high strength and high brittleness, ceramic incurs high costs and long time on finishing process required after sintering. So a process for obtaining wanted measurements of them has been studied using the high temperature which makes ceramics softened and heat affected recently. This study makes an estimate of laser-assisted machining (LAM) if an economically practical process for manufacturing precision silicon nitride ceramic parts using laser beam. In this study, mechanical properties of silicon nitride at high temperature were observed. And during the LAM, it was observed that cutting force and tool wear were reduced and oxidation of machined surface was increased according to a increase of laser power.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2030-2031
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• 2007

This paper is purpose to understand the surge property for the shorted turn or shorted strand in high voltage motor stator windings. a shorted turn in high voltage motor windings causes a huge circulating current. and overheat windings, consequently burns the motor. a few shorted strands not cause winding failure immediately, but they increase the winding loss and temperature increase due to contact resistance. We carried out the surge test for three cases, normal winding, shorted turn winding and shorted strand winding. and we analyzed the test result.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.52-59
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• 2006

Graphite is well known as a material which has high-temperature thermostable property, chemical resistance against acid and alkaline state also is very easy to environment. Nowadays the need of graphite product is increasing rapidly because of its advantages. In this paper, the mechanical property of newly developed graphite products with high density is investigated with especially in compression test. I introduced the graphite specimens for this study by NGF method with two expandable graphite and compared to the specimens of commercial graphite sheet from expanded graphite which made by the rolling process. I investigated the characteristics of these materials by measuring specific weight, hardness, compressive strength and investigating structures by SEM, It is verified that the graphite products with NGF method has superior properties for using gasket materials than that of commercial graphite sheet.

• Journal of IKEEE
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• v.27 no.1
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• pp.25-29
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• 2023

Effect of the processes of polysilazane solid electrolyte layer and silver (Ag) active electrode on the electrical characteristics of memristor was investigated. The memristor with the solid electrolyte annealed at higher temperature exhibited the higher set voltage and better memory retention characteristics than that annealed at lower temperature. The increase in the set voltage and the improvement of the memory retention characteristic at high annealing temperature were attributed to a reduction in the void density and an increase in the void uniformity inside the solid electrolyte, respectively. In the case where the polysilazane solution's concentration is high, the memristor exhibited rapid degradation of low resistive state even annealed at high temperature. Lastly, it was shown that the memristor with the solution-processed Ag active electrode showed WORM property unlike that with the vacuum-processed Ag active electrode. The WORM property was possibly due to morphological defects present in the solution-processed Ag active electrode.

• Journal of Powder Materials
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• v.27 no.1
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• pp.8-13
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• 2020

In this study, we investigated the effects of precipitates and oxide dispersoids on the high-temperature mechanical properties of oxide dispersion-strengthened (ODS) Ni-based super alloys. Two ODS Ni-based super alloy rods with different chemical compositions were fabricated by high-energy milling and hot extrusion process at 1150 ℃ to investigate the effects of precipitates on high-temperature mechanical properties. Further, the MA6000N alloy is an improvement over the commercial MA6000 alloy, and the KS6000 alloy has the same chemical composition as the MA6000 alloy. The phase and microstructure of Ni-based super alloys were investigated by X-ray diffraction and scanning electron microscopy. It was found that MC carbide precipitates and oxide dispersoids in the ODS Ni-based super alloys developed in this study may effectively improve high-temperature hardness and creep resistance.