• Journal of Powder Materials
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• v.30 no.1
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• pp.41-46
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• 2023

In this study, an Al₈₂Ni₇Co₃Y₈ (at%) bulk metallic glass is fabricated using gas-atomized Al₈₂Ni₇Co₃Y₈ metallic glass powder and subsequent spark plasma sintering (SPS). The effect of powder size on the consolidation of bulk metallic glass is considered by dividing it into 5 ㎛ or less and 20-45 ㎛. The sintered Al₈₂Ni₇Co₃Y₈ bulk metallic glasses exhibit crystallization behavior and crystallization enthalpy similar to those of the Al₈₂Ni₇Co₃Y₈ powder with 5 ㎛ or less and it is confirmed that no crystallization occurred during the sintering process. From these results, we conclude that the Z-position-controlled spark plasma sintering process, using superplastic deformation by viscous flow in the supercooled liquid-phase region of amorphous powder, is an effective process for manufacturing bulk metallic glass.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.481-484
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• 2003

In this study, we fabricated the master metallic nano-stamper with nano pillar patterns to apply replication processes which is adequate for mass production. Master nano patterns with various hole diameters between 300 nm and 1000 nm was fabricated by e-beam lithography. After the seed layer was deposited on the master nano patterns using e-beam evaporation, the nickel was electroformed. In each step, the shape and surface roughness of their patterns were analyzed using SEM and AFM.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.259-262
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• 1991

Carbon fiber/Aluminum composites were fabricated vacuum hot press method with condition of $10^{-3}$ torr, 100MPa, $600^{\circ}C$, 30min. Microstructure, mechanical properties, electrical properties and thermal properties of CF/Al composites were studied.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.829-831
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• 2003

In the present study, the electroless plating method was applied instead of the sputtering as a formation method of metallic bus electrodes. No additional blackening step is needed in this method since this process provides a metallic seed layer with black color by a single step. The parameters which affects color and morphology of the metallic seed layer in the electroless plating solution were investigated

• 전기의세계
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• v.19 no.2
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• pp.1-5
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• 1970

According to the previous studies which was done by the author, the flashover voltage was found to be increased considerably if some metallic barriere are inserted into the flashover discharge path. This paper shows that the flashover voltage in suspension insulators and bushings is raised up by the application of metallic barrier effect on surface discharge. Using moderate metallic barrier configulation the flash over voltage can be raised up by the amount of about 15% compared to that of the convensional type of suspension insulatiors and bushings.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.4
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• pp.46-53
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• 1984

The analysis of temperature distribution and change of metallic structures during water quench were presented by finite element method. In temperature calculation the equation of unsteady state hear conduction problem considering latent heat due to phase transformation was applied to finite solid cylinder, SM 45C of 40mm diameter and 40mm height. In metallic structure analysis iso-thermal transformation curve and the equations of evolution in pearlite-martensite transformation were applied. The calculated results upon temperature and metallic structures were agreed with those of experimental observations.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.201-207
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• 2006

• Journal of Powder Materials
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• v.25 no.3
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• pp.246-250
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• 2018

In this study, we investigate the deformation behavior of $Hf_{44.5}Cu_{27}Ni_{13.5}Nb_5Al_{10}$ metallic glass powder under repeated compressive strain during mechanical milling. High-density (11.0 g/cc) Hf-based metallic glass powders are prepared using a gas atomization process. The relationship between the mechanical alloying time and microstructural change under phase transformation is evaluated for crystallization of the amorphous phase. Planetary mechanical milling is performed for 0, 40, or 90 h at 100 rpm. The amorphous structure of the Hf-based metallic glass powders during mechanical milling is analyzed using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Microstructural analysis of the Hf-based metallic glass powder deformed using mechanical milling reveals a layered structure with vein patterns at the fracture surface, which is observed in the fracture of bulk metallic glasses. We also study the crystallization behavior and the phase and microstructure transformations under isothermal heat treatment of the Hf-based metallic glass.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.2
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• pp.297-316
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• 1995

The system and symbolizing ideologic meanings of the metallic Kwon in period of the Three-Kingdoms were comsidered by comparing to their cultural path and structal styles throughout the tree and the deer worship ideology. The results of this study are as followings; Firstly, the beginning of the Korean, mostly northern style was originated from metal tools of the Bronze age in BC 6c-7c. The maJ;lufature of the metallic adornment brought the pr-evailing use of metallic objects of craftwork after the supply of ironmongery. Secondly, the cultmal characteristics of the metallic Kwan in the kor-ean Peninsula were influenced f-rom the northern chinese tribes, Momg Go, Hung No, and Sien-pi who were transmitted from the scythian of the southern Russia having a prefenence for gold. Thir-dly, the metallic Kwon of the Kogmgo and the Baekje era was ideologically based on the ar-t of Buddism of the pattern of blazing flame, the carved pattern of flower- of herb, and the honey. sukle which were tramsmitted to china thr-ough the silk noad. Fourthly, the metallic K wam of the silla era consisted of the tree and the antler types in closely nelated to the tree and the deer ideology which were based on the background of shamanism. It should be raid that the metallic Kwan of the silla esa are connected to the type of nor-them ancient K wan. Lasthy, the metallic Kwan-Mo of the Kaja esa was mosthy original type of flower of herb even if kome of these ar-e similiar to the tree adornment type of silla. This type of flower of herb in based on the scythian type with a statue im silveer founded at Alexandnopol in the southern russia.

• Journal of Power System Engineering
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• v.20 no.4
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• pp.38-43
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• 2016

Safety-related equipments of Nuclear Power Plants(NPP) have to perform environmental qualification test in accordance with IEEE-323 standards. However, non-metallic materials replace new one regularly instead of the test because they are considered as consumable parts. In this study, the seven kinds of non-metallic materials are selected and their activation energy was experimentally evaluated with uncertainty analysis by using thermogravimetric analyzer(TGA). In order to obtain activation energy of non-metallic materials, mass difference, temperature raising rate and conversion rate on the specimen are analyzed. It is postulated that the three experiment conditions are important to get a reliable activation energy. This postulate was experimentally confirmed using Arrhenius equation and Flynn-Wall-Ozawa analysis.