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A Study of the Content Validity of Reading Comprehension Tests in NMET II
Zhen-Jie Liu,Ming-Hao Jin 대한언어학회 2018 언어학 Vol.26 No.4
Liu, Zhen-Jie & Jin, Ming-Hao. (2018). A study of the content validity of reading comprehension tests in NMET II. The Linguistic Association of Korea Journal, 26(4), 103-124. Based on Bachman and Palmer’s (1996) framework of task characteristics, this paper aims to compare the reading comprehension tests of the 2013-2017 National Matriculation English Test II (NMET II) with the requirements of the New Curriculum Standards and Testing Syllabus, in particular, concerning the content validity of the tests in terms of the characteristics of input and expected responses. The implications of this study are discussed for test designers, teachers, and students. The results show that reading comprehension tests from 2013 to 2017 basically meet the requirements of the New Curriculum Standard and Testing Syllabus and have a high content validity. In terms of the characteristics of input, the length, reading speed, and readability of comprehension passages are appropriate for students; however, the distribution of topics and genres in each year is uneven. In terms of the characteristics of expected responses, the wordings of questions and the design of question items are reasonable. However, the response type is mainly restricted to selected response questions (multiple-choice), and the measure of reading skills coverage is unbalanced.
Zhen Shaoming,Liu Chenliang,Liu Xingmou 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2
This paper presents a time–frequency analysis of the vibration of transformer under direct current (DC) bias through Hilbert– Huang transform (HHT). First, the empirical mode decomposition (EMD) process, which is the key in HHT, was introduced. The results of EMD, namely, intrinsic mode functions (IMFs), were calculated and summed by Hilbert transform (HT) to obtain time-dependent series in a 2D time–frequency domain. Next, the theory of DC bias for the transformer was analyzed. In consideration of the DC bias eff ect and in combination with the existing transformer vibration-related mechanism, the electromagnetic force equations of the transformer core were deduced. Lastly, a test system of vibration measurement for the transformer was set up. Three direction (x, y, and z axes) components of core vibration were measured. Decomposition of EMD and HHT spectra showed that vibration strength increased, and odd harmonics were produced with DC bias. This method illustrates the most obvious vibration distortion in the z-axis direction when the transformer is DC biased. Among them, the distortion of IMF3 has increased by more than 5 times. However, the distortion in the x-axis and y-axis directions also exists, but it is not obvious. Especially, 50 Hz component appeared in z-direction, 50 Hz component increased twofold in y-direction, and 150 Hz component increased threefold in z-direction. Results indicated that HHT can not only provide the occurrence time of DC bias but can also obtain the signal change components of the transformer vibration. Thus, HHT is a viable signal processing tool for transformer health monitoring.
The Use of Newspaper Articles to Enhance the Reading Proficiency of Chinese EFL Learners
( Zhen Liu ),( Xiaohong Zhang ),( Seung-man Kang ) 대한영어영문학회 2022 영어영문학연구 Vol.48 No.2
Reading plays a critical role in improving the language proficiency of EFL learners. Indispensable to this end are appropriate reading materials for them to use in their reading class or on their own. This paper attempts to investigate the pedagogical effects of using newspaper articles as an authentic reading material. For our discussion, we take a survey among 65 Chinese EFL college students to find out their attitude towards news reading materials, strategies for reading, and enhancement in reading comprehension. The findings of the survey reveal that the teaching of these reading materials via explicit instruction exerts positive effects on the three objectives as follows. First, the paired-sample t-test of the pre-Q and the post-Q shows that teaching English newspaper materials improves the students’ attitude towards English reading. Second, this test also shows that the students have greatly improved their reading strategies for reading. Third, the results of the paired-sample t-test and the independent t-test indicate that there is significant improvement in reading comprehension after explicit instruction. (Chungbuk National University)
Experimental study on multi-level overtopping wave energy convertor under regular wave conditions
Zhen Liu,Zhi Han,Wanchang Yang 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.5
A multi-level overtopping wave energy converter was designed according to the large tidal range and small wave heights in China. It consists of two reservoirs with sloping walls at different levels. The reservoirs share a common outflow duct and a low-head axial turbine. The experimental study was carried out in a laboratory wave-flume to investigate the overtopping performance of the device. The depth-gauges were used to measure the variation of the water level in the reservoirs. The data was processed to derive the time-averaged overtopping discharges. It was found that the lower reservoir can store wave waters at the low water level and break the waves which try to climb up to the upper reservoir. The upper sloping angle and the opening width of the lower reservoir both have significant effects on the overtopping discharges, which can provide more information to the design and optimization of this type of device.
Liu Zhen,Ouyang Guoqing,Lu Wuchang,Zhang Huiming 한국유전학회 2021 Genes & Genomics Vol.43 No.8
Background Hepatocellular carcinoma (HCC) is one of the most common human cancers. Long non-coding RNAs (lncRNAs) play pivotal roles in progression of various cancers, including HCC. Objective We aimed to explore the exact role and underlying mechanism of lncRNA HOX transcript antisense intergenic RNA (HOTAIR) in HCC. Methods Quantitative real time polymerase chain reaction (qRT-PCR) was carried out to determine the levels of HOTAIR, DEAH-box helicase 33 (DHX33) and miR-526b-3p. Western blot assay was used to detect the protein level of DHX33. Besides, cell proliferation and apoptosis were assessed by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and fow cytometry analysis, respectively. Cell migration and invasion were detected by transwell assay. The interaction between miR-526b-3p and HOTAIR or DHX33 was predicted by starbase and confrmed by the dual-luciferase reporter assay. Murine xenograft model was established through injecting Huh7 cells transfected with sh-NC or sh-HOTAIR. Results The levels of HOTAIR and DHX33 were increased in HCC tissues and cells. Knockdown of either HOTAIR or DHX33 suppressed proliferation, migration and invasion but increased apoptosis in HCC cells. Moreover, DHX33 overexpression reversed the suppressive efect of HOTAIR knockdown on progression of HCC cells. Interestingly, miR-526b-3p could directly bind to HOTAIR, and DHX33 was a direct target of miR-526b-3p. Additionally, interference of HOTAIR restrained the tumor growth by upregulating miR-526b-3p and downregulating DHX33 in vivo. Conclusions HOTAIR knockdown suppressed cell proliferation, migration and invasion, and promoted apoptosis via regulating miR-526b-3p/DHX33 axis in HCC cells, providing a potential avenue for treatment of HCC.
Megahertz ZVS transformerless interleaved inverter for dielectric barrier discharge lamps
Liu, Zhen The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4
A transformerless zero-voltage switching (ZVS) megahertz interleaved inverter is proposed in this paper to improve the driving efficiency of dielectric barrier discharge (DBD) lamps. The proposed inverter consists of two inductors and two metal oxide semiconductor field effect transistors (MOSFETs). The MOSFETs operate in the interleaving mode and the energy injected into the DBD device is controlled by adjusting the turn-on time or frequency of the switching devices. Various waveforms can be realized by controlling the phase difference of the pulses. The operational principles were analyzed and the circuit was simulated. A prototype was built and demonstrated. Experiment results show that the proposed inverter can achieve ZVS and generate high-voltage bipolar pulses with a frequency range from several kilohertz to 1 MHz. A short pulse with a steep rise time of 40 ns, a peak-to-peak voltage of 1400 V and full width at half the maximum of 220 ns at a frequency of 1 MHz can be achieved. The lamp efficiency was increased by more than 7% when compared with the lamp driven at kilohertz. Therefore, it is suggested that the proposed inverter is suitable for driving the dielectric barrier discharge lamps efficiently with a simple structure.