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      • KCI등재

        The effectiveness of private tutoring: students’ perceptions in comparison with mainstream schooling in Hong Kong

        Shengli Zhan,Mark Bray,Dan Wang,Chad Lykins,Ora Kwo 서울대학교 교육연구소 2013 Asia Pacific Education Review Vol.14 No.4

        This paper examines Hong Kong students’ perceptions on the effectiveness of private supplementary tutoring relative to mainstream schooling. Drawing on survey and interview data, it shows that large proportions of secondary school students receive private tutoring. Students generally perceive private tutoring and private tutors to be more effective in the provision of examination support compared with mainstream schooling and teachers. However, perceptions vary according to students’ self-reported academic levels and motives for taking private tutoring. The operations of the parallel sector of private tutoring have significant implications for the nature of schooling and therefore need to be considered by teachers and school administrators. The Hong Kong data contribute to the international analysis of private tutoring and add a significant component to the wider conceptual literature.

      • A LSTM-based method for intelligent prediction on mechanical response of precast nodular piles

        Sheng-Liang Lu,Xiao-Xiao Chen,Chang-Sheng Zhan 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.2

        The determination for bearing capacity of precast nodular piles is conventionally time-consuming and high-cost by using numerous experiments and empirical methods. This study proposes an intelligent method to evaluate the bearing capacity and shaft resistance of the nodular piles with high efficiency based on long short-term memory (LSTM) approach. A series of field tests are first designed to measure the axial force, shaft resistance and displacement of the combined nodular piles under different loadings, in comparison with the single pre-stressed high-strength concrete piles. The test results confirm that the combined nodular piles could provide larger ultimate bearing capacity (more than 100%) than the single pre-stressed highstrength concrete piles. Both the LSTM-based method and empirical methods are used to calculate the shift resistance of the combined nodular piles. The results show that the LSTM-based method has a high-precision estimation on shaft resistance, not only for the ultimate load but also for the working load.

      • SCIESCOPUSKCI등재
      • KCI등재

        New DTR Estimation Method Without Measured Solar and Wind Data

        Zhan-Feng Ying,Yuan-Sheng Chen,Kai Feng 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

        Dynamic thermal rating (DTR) of overhead transmission lines can provide a significant increase in transmission capacity compared to the static thermal rating. However, the DTR are usually estimated by the traditional thermal model of overhead conductor that is highly dependent on the solar, wind speed and wind direction data. Consequently, the estimated DTR would be unreliable and the safety of transmission lines would be reduced when the solar and wind sensors are out of function. To address this issue, this study proposed a novel thermal model of overhead conductor based on the thermal-electric analogy theory and Markov chain. Using this thermal model, the random variation of conductor temperature can be simulated with any specific current level and ambient temperature, even if the solar and wind sensors are out of function or uninstalled. On this basis, an estimation method was proposed to determine the DTR in the form of probability. The laboratory experiments prove that the proposed method can estimate the DTR reliably without measured solar and wind data.

      • Integrated Protection Unit Design for Power Networks

        Zhan-feng Fan,Sheng-ming Ge,Z Q Bo,Lin Wang,Feng-quan Zhou,Xing Liu,Guo-bing Song 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.4

        This paper presents an hardware design solution for integrated protection of distribution systems (Network Protection Unit) by combining transient polarity comparison technique, which is based on the detection and processing of fault generated transient current signals. The integrated protection relays installed at each substation of a distribution network are communicated with the Network Protection Unit through specially designed Packet Transport Network (PTN) for fast and reliable transmission of transient polarity current signals. The relay detects the faulted generated super-imposed current signals. The transient polarity identification algorithm is then applied to the super-imposed signals to identify the polarity of the signal detected. The Network Protection Unit can collect all the transient polarity current signals under its protection area. Then The direction of a fault is determined by comparison of the polarity of the signals derived from all the line sections connected to the substation. The actual faulted section is identified by the Network Protection Unit through comparing the directional information from various stations. Simulation results presented in the paper demonstrate the feasibility of the scheme.

      • Let-7c Inhibits NSCLC Cell Proliferation by Targeting HOXA1

        Zhan, Min,Qu, Qiang,Wang, Guo,Liu, Ying-Zi,Tan, Sheng-Lan,Lou, Xiao-Ya,Yu, Jing,Zhou, Hong-Hao Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

        Objective: The aim of the present study was to explore mechanisms by which let-7c suppresses NSCLC cell proliferation. Methods: The expression level of let-7c was quantified by qRT-PCR. A549 and H1299 cells were transfected with let-7c mimics to restore the expression of let-7c. The effects of let-7c were then assessed by cell proliferation, colony formation and cell cycle assay. Mouse experiments were used to confirm the effect of let-7c on tumorigenicity in vivo. Luciferase reporter assays and Western blotting were performed to identify target genes for let-7c. Results: HOXA1 was identified as a novel target of let-7c. MTS, colony formation and flow cytometry assays demonstrated that forced expression of let-7c inhibited NSCLC cell proliferation by inducing G1 arrest in vitro, consistent with inhibitory effects induced by knockdown of HOXA1. Mouse experiments demonstrated that let-7c expression suppressed tumorigenesis. Furthermore, we found that let-7c could regulate the expression of HOXA1 downstream effectors CCND1, CDC25A and CDK2. Conclusions: Collectively, these results demonstrate let-7c inhibits NSCLC cell proliferation and tumorigenesis by partial direct targeting of the HOXA1 pathway, which suggests that restoration of let-7c expression may thus offer a potential therapeutic intervention strategy for NSCLC.

      • KCI등재

        Case Study of the Effect of Rainfall Infiltration on a Tunnel Underlying the Roadbed Slope with Weak Inter-Layer

        Sheng-yuan Fan,Zhan-ping Song,Yu-wei Zhang,Nai-fei Liu 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.5

        It is a common type of tunnel under-cross the roadbed slope with weak inter-layer. Rainfall infiltration will cause soil softening, matric suction and strength reduction, which seriously threaten the safety of slope and tunnel. This paper presents a case where a tunnel underlying the roadbed slope with weak inter-layer in Guiyang 1# line, China. The seepage calculation model in MIDAS GTS/NX software, considering hydraulic permeability coefficient characteristiccurve and soil-water characteristic curve, was used to analyze the stress and deformation of the roadbed slope and tunnel. The results reveal that rainfall infiltration has great influence on the deformation of roadbed slope with weak inter-layer and the force of internal tunnel. Slope displacement increases rapidly in the early stage and decreases in the late stage, but the absolute value of displacement increases continuously and the slope safety factor decreases gradually, which makes the slope in a dangerous state. The force of tunnel lining increases in the early stage and decreases with the recovery of soil strength after rainfall. The control effects of anchor cable and anti-slide pile reinforcement on slope sliding and tunnel stress were studied. And the anchor cable reinforcement measure is more effective on reducing slope slip and tunnel lining structure internal force.

      • KCI등재

        Performance of Hepatitis B Core-Related Antigen Versus Hepatitis B Surface Antigen and Hepatitis B Virus DNA in Predicting HBeAg-positive and HBeAg-negative Chronic Hepatitis

        Zhan-qing Zhang,Yan-bing Wang,,Wei Lu,,Dan-ping Liu,,Bi-sheng Shi,,Xiao-nan Zhang,,Dan Huang,,Xiu-fen Li,,Xin-lan Zhou,,Rong-rong Ding, 대한진단검사의학회 2019 Annals of Laboratory Medicine Vol.39 No.1

        Background: We examined changes in hepatitis B core-related antigen (HBcrAg) during the four sequential phases of chronic hepatitis B virus (HBV) infection: hepatitis B e antigen (HBeAg)-positive chronic infection (EPCI) and hepatitis (EPCH), followed by HBeAg-negative chronic infection (ENCI) and hepatitis (ENCH). We compared the performance of serum HBcrAg, hepatitis B surface antigen (HBsAg), and HBV DNA in predicting EPCH and ENCH.

      • Performance Analysis of Packet Transport Network Communication for Integrated Wide-Area Protection

        Sheng-ming Ge,Z Q Bo,Lin Wang,Zhan-feng Fan,Xing Liu,Feng-quan Zhou 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.3

        As a new protection, wide-area protection enables protective relaying, and automatic control based on electric power system network communications and comprehensive judgment of multi-point information, which plays an increasingly important role in the secure and stable operation of electric power system. Interaction of wide-area information relies on communication network featuring high reliability and low time delay. On the other hand, most service of power transformation station is gradually towards IP and data oriented, along with the development of smart grid. This paper aims to introduce the wide-area protection technology supported by Packet Transport Network (PTN) communication technology, with analyzing the QoS (Quality of Service) network assurance architecture of PTN network, which establishes three planes, including transport plane, management plane, and control plane, based on ASON (Automatically Switched Optical Network) technology. After demonstrating the QoS assurance system of PTN from traffic control and transmission route, this paper introduces PTN networking test. Based on detailed parameters in the test results, the transmission performance of PTN on time delay, protection, and time synchronization of various electric power communication services are analyzed, with showing that PTN can fully meet the requirements of electric power communication.

      • SCIESCOPUSKCI등재

        New DTR Estimation Method Without Measured Solar and Wind Data

        Ying, Zhan-Feng,Chen, Yuan-Sheng,Feng, Kai The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

        Dynamic thermal rating (DTR) of overhead transmission lines can provide a significant increase in transmission capacity compared to the static thermal rating. However, the DTR are usually estimated by the traditional thermal model of overhead conductor that is highly dependent on the solar, wind speed and wind direction data. Consequently, the estimated DTR would be unreliable and the safety of transmission lines would be reduced when the solar and wind sensors are out of function. To address this issue, this study proposed a novel thermal model of overhead conductor based on the thermal-electric analogy theory and Markov chain. Using this thermal model, the random variation of conductor temperature can be simulated with any specific current level and ambient temperature, even if the solar and wind sensors are out of function or uninstalled. On this basis, an estimation method was proposed to determine the DTR in the form of probability. The laboratory experiments prove that the proposed method can estimate the DTR reliably without measured solar and wind data.

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