Journal of Powder Materials

Ji-Hun Yu

6 Articles

Trend in Research and Development Related to Lean Heavy Rare-earth Permanent Magnets for Next-generation Motors: Jung-Goo Lee, Youn-Kyoung Baek, Ji-Hun Yu, Chul-Jin Choi; J Korean Powder Metall Inst. 2012;19(2):151-159.; DOI: https://doi.org/10.4150/KPMI.2012.19.2.151

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Study on the Demagnetization and Classification of NdFeB Magnets According to Different Heat Treatment Temperatures
Byeong Jun Kim, Ik Keun Park, Young Sung Kim
Journal of the Korean Society of Manufacturing Technology Engineers.2021; 30(2): 119. CrossRef
Low Cost Design Study of Brushless DC Motor for Electric Water Pump Application
Tae-Uk Jung
Journal of Electrical Engineering and Technology.2014; 9(3): 942. CrossRef
Optimized Design of Rotor Considering Cost-Reduction of Small BLDC Motor for the Water Pump
Hoe-Cheon Kim, Tae-Uk Jung
The Transactions of The Korean Institute of Electrical Engineers.2013; 62(4): 495. CrossRef

Synthesis of Zr-Ti Alloy Powder by Magnesium Reduction: Dong-Won Lee, Geun-Tae Park, Tae-Soo Lim, Hye-Moon Lee, Ji-Hun Yu; J Korean Powder Metall Inst. 2011;18(4):359-364.; DOI: https://doi.org/10.4150/KPMI.2011.18.4.359

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Zr-Ti alloy powders were successfully synthesized by magnesium thermal reduction of metal chlorides. The evaporated and mixed gasses of ZrCl_4+TiCl_4 were injected to liquid magnesium and the chloride components were reduced by magnesium leading to the formation of MgCl_2. The released Zr and Ti atoms were then condensed to particle forms inside the mixture of liquid magnesium and magnesium chloride, which could be dissolved fully in post process by 1~5% HCl solution at room temperature. By the fraction-control of individually injected ZrCl_4 and TiCl_4 gasses, the final compositions of produced alloy powders were changed in the ranges of Zr-0 wt.%~20 wt.%Ti and their purity and particle size were about 99.4% and the level of several micrometers, respectively.

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Synthesis of Vanadium Powder by Magnesiothermic Reduction
Dong Won Lee, Hak Sung Lee, Jung Yeul Yun, Young Ho Kim, Jei Pil Wang
Advanced Materials Research.2014; 1025-1026: 509. CrossRef
Extraction of Vanadium Powder by Metallothermic Reduction
Dong-Won Lee, Sang-Hyun Heo, Jong-Taek Yeom, Jei-Pil Wang
Journal of Korean Powder Metallurgy Institute.2013; 20(1): 43. CrossRef

A study on Magnetic Properties of BaFe₁₂O₁₉ Fabricated by Ultrasonic Spray-pyrolysis Process Using Self-Assembly Method: Moon-Hee Choi, Ji-Hun Yu, Dong-Hwan Kim, Kook-Chae Chung, Yang-Do Kim; J Korean Powder Metall Inst. 2010;17(4):263-269.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.263

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Hexagonal barium ferrite (BaFe_12O_19) nano-particles have been successfully fabricated by spraypylorysis process. BaFe_12O_19 precursor solutions were synthesized by self-assembly method. Diethyleneamine (DEA) surfactant was used to fabricate the micelle structure of Ba-DEA complex under various DEA concentrations. BaFe_12O_19 powders were synthesized with addition of Fe ions to Ba-DEA complex and then fabricated BaFe_12O_19 powders by spray-pyrolysis process at the temperature range of 800sim1000°C. The molar ratio of Ba/DEA and heat-treatment temperatures significantly affected the magnetic properties and morphology of BaFe_12O_19 powders. BaFe_12O_19 powders synthesized with Ba/DEA molar ratio of 1 and heat-treated at 900°C showed the coercive forces (iHc) of 4.2 kOe with average crystal size of about 100 nm.

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Synthesize of Nd₂Fe₁₄B Powders from 1-D Nd₂Fe₁₄B Wires using Electrospinning Process
Nu Si A Eom, Su Noh, Muhammad Aneeq Haq, Bum Sung Kim
Journal of Korean Powder Metallurgy Institute.2019; 26(6): 477. CrossRef

The Present Issues of Rare Earth Magnetic Powder for Bonded Magnets: Dong-Hwan Kim, Ji-Hun Yu; J Korean Powder Metall Inst. 2010;17(2):81-87.; DOI: https://doi.org/10.4150/KPMI.2010.17.2.081

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Preparation of Highly Efficient Nd-Fe-B Magnetic Powders by Reduction/Diffusion Process
Dongsoo Kim, Chunqiang Chen, Younkyoung Baek, Chuljin Choi
Journal of Korean Powder Metallurgy Institute.2013; 20(3): 197. CrossRef

A Study on Magnetic Properties of BaFe₁₂O_₁₉ Fabricated by Self-assembly Method: Moon-Hee Choi, Ji-Hun Yu, Dong-Hwan Kim, Hye-Mum Lee, Su-Min Kim, Yang-Do Kim; J Korean Powder Metall Inst. 2009;16(6):410-415.; DOI: https://doi.org/10.4150/KPMI.2009.16.6.410

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Hexagonal barium ferrite (BaFe_12O_19) nano-particles have been successfully synthesised using selfassembly method. Diethyleneamine (DEA) surfactant was used to fabricate the micelle structure of Ba-DEA complex under various DEA concentrations. BaFe_12O_19 powders were synthesized with addition Fe ions to Ba-DEA complex and then heat treated at temperature range of 800-1000°C. The molar ratio of Ba/DEA and heat-treatment temperature significantly affected the magnetic properties and morphology of BaFe_12O_19 powders. BaFe_12O_19 powders synthesized with Ba/DEA molar ratio of 1 and heat-treated at 1000°C for 1 hour showed the coercive forces (iHc) of 4.84 kOe with average crystal size of about 200 nm.

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A study on Magnetic Properties of BaFe12O19Fabricated by Ultrasonic Spray-pyrolysis Process Using Self-Assembly Method
Moon-Hee Choi, Ji-Hun Yu, Dong-Hwan Kim, Kook-Chae Chung, Yang-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(4): 263. CrossRef

Characteristics of L1₀ Ordered Fe₅₀Pt₅₀ Nanoparticles Synthesized by Chemical Vapor Condensation Process: Gyeong-Mo Lee, Ji-Hun Yu, Dong-Won Lee, Byung-Kee Kim, Hyeok-Don Kim, Tae-Suk Jang; J Korean Powder Metall Inst. 2007;14(5):281-286.; DOI: https://doi.org/10.4150/KPMI.2007.14.5.281

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Abstract PDF: Ordered L1_0 to FePt nanoparticles are strong candidates for high density magnetic data storage media because the L1_0 phase FePt has a very high magnetocrystalline anisotropy (K_usim6.6-10times107erg/cm3), high coercivity and chemical stability. In this study, the ordered L1_0 FePt nanoparticles were successfully fabricated by chemical vapor condensation process without a post-annealing process which causes severe particle growth and agglomeration. The Fe_50Pt_50 nanopowder was obtained when the mixing ratio of Fe(acac) and Pt(arac) was 2.5 : 1. And the synthesized FePt nanoparticles were very fine and spherical shape with a narrow size distribution. The average particle size of the powder tended to increase from 5 nm to 10 nm with increasing reaction temperature from 800°C to 1000°C. Characterisitcs of FePt nanopowder were investigated in terms of process parameters and microstructures.

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