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Wyszukujesz frazę "Park, Seung-Young" wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Improvement of Microwave Absorption Characteristics by Coating Layer in Substituted U-Type Ferrites
Autorzy:
Jeong, Kwang-Pil
Kim, Jeong-Gon
Yang, Su-Won
Choi, Jin-Hyuk
Park, Seung-Young
Powiązania:
https://bibliotekanauki.pl/articles/353196.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hexagonal ferrite
U-type ferrite
silicon oxide layer
microwave absorption
Opis:
The U-type ferrite is a kind of hexagonal ferrite, and it is known as a microwave absorber in the X-band. The magnetic and dielectric loss of the U-type ferrite change to the composition and coating layer, etc. In this study, the silicon oxide layer was coated on the substituted U-type ferrites to improve microwave absorption characteristics. The complex permittivity and complex permeability were measured using toroidal specimens that were press-molded and the measured frequency range was set from 2-18 GHz. The improvement of the microwave absorption rate was different according to the type of the substituted U-type ferrites. Only in the substituted U-type ferrites with nickel and zinc, an improvement in the microwave absorption rate due to enhancement of magnetic loss was confirmed. The highest microwave absorption was 99.9% at 9.6 GHz, which was S_Z0.5 U.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1287-1291
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Mg Ratio on the Extraction of Dy from (Nd,Dy)-Fe-B Permanent Magnet Using Liquid Mg
Autorzy:
Park, Sang-Min
Nam, Sun-Woo
Cho, Ju-Young
Lee, Sang-Hoon
Hyun, Seung-Keun
Kim, Taek-Soo
Powiązania:
https://bibliotekanauki.pl/articles/353657.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dysprosium
liquid metal extraction
(Nd,Dy)-Fe-B magnet
extraction behavior
diffusion
Opis:
Recently, since the demand of rare earth permanent magnet for high temperature applications such as an electric motor has increased, dysprosium (Dy), a heavy rare earth element, is becoming important due to severe bias in its production. To fulfillthe increasing need of Dy, recycling offers as a promising alternative. In recycling of rare earths, Hydro-metallurgical extraction method is mainly used however it has adverse environmental effects. Liquid metal extraction on the other hand, is an eco-friendly and simple method as far as the reduction of rare earth metal oxide is concerned. Therefore, liquid metal extraction was studied in this research as an alternative to the hydro-metallurgical recycling method. Magnesium (Mg) is selected as solvent metal because it doesn’t form intermetallic compounds with Fe, B and has a low melting and low boiling point. Extraction behavior of Dy in (Nd,Dy)-Fe-B magnet is observed and effect of Mg ratio on extraction of Dy is confirmed.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1281-1285
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Process Variables on Friction Stirred Microstructure and Surface Hardness of AZ31 Magnesium Alloy
Autorzy:
Kim, Jae-Yeon
Hwang, Jung-Woo
Lee, Seung-Mi
Hyun, Chang-Young
Park, Ik-Keun
Byeon, Jai-Won
Powiązania:
https://bibliotekanauki.pl/articles/355106.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
friction stir process
AZ31 alloy
diamond particle
process variable
grain size
Opis:
Effects of various friction stir processing (FSP) variables on the microstructural evolution and microhardness of the AZ31 magnesium alloy were investigated. The processing variables include rotational and travelling speed of the tool, kind of secondphase (i.e., diamond, Al2 O3 , and ZrO2 ) and groove depth (i.e., volume fraction of second phase). Grain size, distribution of second phase particle, grain texture, and microhardness were analyzed as a function of the FSP process variables. The FSPed AZ31 com-posites fabricated with a high heat input condition showed the better dispersion of particle without macro defect. For all composite specimens, the grain size decreased and the microhardness increased regardless of the grooved depth compared with that of the FSPed AZ31 without strengthening particle, respectively. For the AZ31/diamond composite having a grain size of about 1 μm, microhardness (i.e., about 108 Hv) was about two times higher than that of the matrix alloy (i.e., about 52 Hv). The effect of second phase particle on retardation of grain growth and resulting hardness increase was discussed.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 907-911
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Principal Instructional Leadership and Teaching for Learner Autonomy: A Multilevel Analysis of the Case of South Korea
Autorzy:
Ham, Seung-Hwan
Ahn, Sung-Ho G.
Cha, Yun-Kyung
Ju, Mi-Kyung
Kim, Sunah
Ku, Hara
Lee, Sun-Kyung
Park, Young Serk
Powiązania:
https://bibliotekanauki.pl/articles/18104543.pdf
Data publikacji:
2013-09-30
Wydawca:
Wydawnictwo Adam Marszałek
Opis:
This study aims to explore how teachers’ use of instructional strategies to foster learner autonomy varies depending on principal instructional leadership. Based on a nationally representative sample of approximately 2,200 teachers in 131 middle schools in South Korea, a series of hierarchical generalized linear modeling analyses has been conducted. The main findings from this study lend credence to the idea that teachers whose school principals provide greater instructional leadership are significantly more likely to integrate instructional strategies to advance learner autonomy into their classroom teaching. This result appears very robust even after a range of variables pertaining to school and teacher characteristics is simultaneously taken into account.
Źródło:
The New Educational Review; 2013, 33; 247-260
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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