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Yuhuan Zhang,Yu Dang,Yahan He,Xiao Ma,Lidong Wang 서울대학교 교육연구소 2021 Asia Pacific Education Review Vol.22 No.2
In general, private supplementary tutoring is considered an effective means of improving academic achievement by parents. However, previous studies have produced partial or inconclusive results regarding its effectiveness. Thus, the present study conducted a comprehensive analysis based on a specially designed longitudinal survey of private supplementary mathematics tutoring among middle school students in China. The hierarchical linear analysis did not show a considerably significant positive effect of regular private tutoring, even when such tutoring continued throughout the summer vacation and school semester. The data also allowed a deeper inquiry into the role of the quality, quantity, and applicability of private tutoring. In addition, the heterogeneous effect of private supplementary tutoring across students with different mathematics achievement levels was explored, with possible explanations including the different learning styles of students from different groups, the ceiling effect of the testing tool, and the different learning needs of different groups of students. These results suggest that parents should carefully select private tutoring for their children, and that the government should provide more comprehensive professional guidelines to regulate the industry.
Wentao Qiao,Yuhuan Wang,Renjie Zhu,Ruifeng Li,Mingshan Zhao 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.6
To solve the shortcomings of single-limb or double-limb cold-formed thin-walled steel column easy to buckling failure and low bearing capacity, a new cross-shaped built-up cold-formed thin-walled steel multi-limb-section is proposed for columns. The structure is composed of several single-limb cold-formed thin-walled steel C-channel sections. The flanges and webs are connected by self-drilling screws. In order to assess the mechanical properties of this built-up multi-limb-section column and the influence of the slenderness ratio on the column behavior, the axial loading tests were carried out. Three kinds of single-limb column and built-up multi-limb-section column with different ratio of slenderness were tested. The deformation process, failure mode and bearing capacity were analyzed. The SC specimens failed with local buckling and distorted buckling, while the MC and LC specimens failed with local buckling and global instability. For the built-up multi-limb-section column, the section combination multiple is 12. Compared to the section combination multiple, the bearing capacity combination multiple is much higher. The SQ specimens’ combination factor is about 1.1, the combination factor of MQ specimens and LQ specimens are about 1.4 and 3.0, respectively. It is concluded that the overall combined-performance and structural efficiency of the specimens is proportional to the combination factor.