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Akademický článek

The Cause of Institutionalized Private Tutoring in Korea: Defective Public Schooling or a Universal Desire for Family Reproduction?

Autor: Sang Hoon Bae (배상훈), Kee Ho Choi (최기호)

Publikováno v: ECNU Review of Education, Vol 7 (2024)

Purpose In Korea, private tutoring is considered a social evil that damages the capacity of public schooling and undermines social justice. Although the government has implemented various policies to reduce private tutoring, ranging from improving th

Externí odkaz: https://doaj.org/article/2f475629df1f402ab0ca84ee37a5ddd2

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New Half-Metallocene Catalysts Generating Polyethylene with Bimodal Molecular Weight Distribution and Syndiotactic Polystyrene

Autor: Bo Geun Song, Yonggyu Han, Seung Woong Yoon, Min Hyung Lee, Youngkyu Do, Youngjo Kim, Kee Ho Choi

Publikováno v: Macromolecular Rapid Communications. 22:573-578

A new type of half-metallocene catalyst for the polymerization of ethylene and styrene Cp * M((O) 3 O 9 Si 7 (c-C 5 H 9 ) 7 ) (M= Ti (1), Zr (2)) is prepared by the reaction of (HO) 3 O 9 Si 7 (c-C 5 H 9 ) 7 with Cp * MCl 3 in the presence of triethy

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::d962c32b539540e17997ce882cb850bf
https://doi.org/10.1002/1521-3927(20010501)22:8<573::aid-marc573>3.0.co

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Control of molecular weight distribution (MWD) for polyethylene catalyzed over Ziegler-Natta/Metallocene hybrid catalysts

Autor: Dae Jung Choi, Wha Young Lee, Han Seock Cho, Kee Ho Choi

Publikováno v: Korean Journal of Chemical Engineering. 17:205-209

Two types of inorganic supports, MgCl2 and SiO2, for the impregnation of catalysts were prepared by the recrystallization and sol-gel methods, respectively. The Ziegler-Natta/Metallocene hybrid catalysts were prepared in order to control the molecula

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::c7d2b2a6bcb24f909c62a5aa04dc6005
https://doi.org/10.1007/bf02707144

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Ziegler-Natta/Metallocene Hybrid Catalysts on SiO2/MgCl2 Bisupport for the Ethylene Polymerization with Respect to the Mg/Si Mole Ratio

Autor: Jin Suk Chung, Young Gwan Ko, Wha Young Lee, Han Seock Cho, Kee Ho Choi

Bisupport for the olefin polymerization was prepared by the gelation of the colloidal phase of SiCO2 using MgCl2 solution as an initiator. The prepared Ziegler-Natta/Metallocene hybrid catalysts on the bisupport exhibited the characteristics of both

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::f96e1add058898512821d4b686521d24
https://doi.org/10.1016/s0167-2991(99)80124-4

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