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.

Synergistic Effect of Bone Marrow-Derived Mesenchymal Stem Cells and Platelet-Rich Plasma in Streptozotocin-Induced Diabetic Rats

( Zhen Zhen Lian ),( Xiao Jing Yin ),( Hua Li ),( Li Li Jia ),( Xiu Zhen He ),( Yong Bo Yan ),( Nai Hua Liu ),( Ka Yiu Wan ),( Xiao Kun Li ),( Shao Qiang Lin ) 대한피부과학회 2014 Annals of Dermatology Vol.26 No.1

Background: Diabetic wounds are a major clinical challenge, because minor skin wounds can lead to chronic, unhealed ulcers and ultimately result in infection, gangrene, or even amputation. Studies on bone marrow derived mesenchymal stem cells (BMSCs) and a series of growth factors have revealed their many benefits for wound healing and regeneration. Platelet-rich plasma (PRP) may improve the environment for BMSC development and differentiation. However, whether combined use of BMSCs and PRP may be more effective for accelerating diabetic ulcer healing remains unclear. Objective: We investigated the efficacy of BMSCs and PRP for the repair of refractory wound healing in a diabetic rat model. Methods: Forty-eight rats with diabetes mellitus induced by streptozotocin were divided into four groups: treatment with BMSCs plus PRP, BMSCs alone, PRP alone, phosphate buffered saline. The rate of wound closure was quantified. A histopathological study was conducted regarding wound depth and the skin edge at 7, 14, and 28 days after surgery. Results: Wound healing rates were significantly higher in the BMSC plus PRP group than in the other groups. The immunohistochemistry results showed that the expression of platelet/endothelial cell adhesion molecule 1, proliferating cell nuclear antigen, and transforming growth factor-β1 increased significantly in the BMSC plus PRP group compared to the other treatment groups. On day 7, CD68 expression increased significantly in the wounds of the BMSC plus PRP group, but decreased markedly at day 14 compared to the controls. Conclusion: The combination of BMSCs and PRP aids diabetic wound repair and regeneration. (Ann Dermatol 26(1) 1∼10, 2014)

Joint Correction of Ionosphere Noise and Orbital Error in L-Band SAR Interferometry of Interseismic Deformation in Southern California

Zhen Liu,Hyung-Sup Jung,Zhong Lu IEEE 2014 IEEE transactions on geoscience and remote sensing Vol.52 No.6

<P>The accuracy of L-band synthetic aperture radar (SAR) differential interferometry (InSAR) on crustal deformation studies is largely compromised by ionosphere path delays on the radar signals. The ionosphere effects cause severe ionospheric distortion such as azimuth streaking and long wavelength phase distortion similar to orbital ramp error. Effective detection and correction of ionospheric phase distortion from L-band InSAR images are necessary to measure and accurately interpret surface displacement. In this paper, we investigate the performance improvement of L-band InSAR interseismic deformation measurements in southern California through the joint correction of both ionosphere noise and orbital error. Our results show that this method can effectively remove orbit and ionosphere phase distortions. In comparison with in situ GPS measurements, the achieved InSAR measurement accuracy is improved from ~ 30 mm to ~ 10 mm by the proposed joint correction method. We show that, after the joint correction, the remaining atmosphere noise can be further mitigated through stacking, leading to an RMS error of ~ 4.7 mm/year in resultant line-of-sight velocity, as compared with ~ 11.3 mm/year before the correction. Our results demonstrate that the proposed joint correction technique provides a promising way to jointly correct orbital and ionospheric artifacts in L-band InSAR studies of crustal deformation.</P>

Facile synthesis of polypyrrole coated copper nanowires: a new concept to engineered core–shell structures

Liu, Yang,Liu, Zhen,Lu, Ning,Preiss, Elisabeth,Poyraz, Selcuk,Kim, Moon J.,Zhang, Xinyu The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.20

<P>Polypyrrole coated copper nanowires were synthesized in a one-pot manner in the presence of cupric precursor and pyrrole. They displayed ultra-high sensitivity as a potentiometric sensor with considerable environmental stability comparable to noble metals.</P> <P>Graphic Abstract</P><P>Polypyrrole coated copper nanowires (PPy-CuNWs) were obtained in one-pot synthesis, which possess outstanding chemical sensing properties and environmental stability. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc16961d'> </P>

Solid State Reaction Synthesis and Thermoelectric Properties of Ag-Doped Mg₂Si_0.8Ge_0.2

Liu, Qiong Zhen,Zhang, Lian Meng,Shen, Qiang,Jiang, Hong Yi,Wang, Chuan Bin Trans Tech Publications, Ltd. 2006 Key engineering materials Vol.313 No.-

<P>By two-step solid state reaction, Mg2Si0.8Ge0.2 was successfully synthesized .The effect of Ag-doping concentration on the thermoelectric transport properties of p-type Mg2Si0.8Ge0.2 was investigated. With the increasing of Ag-doping concentration, the electrical conductivity σ and Seebeck coefficient α increase correspondingly over the measuring temperature range (300-800K).The peaks of the curves of Seebeck coefficient versus temperature shift towards the lower temperature .When the doping concentration of Ag is 16000ppm(nominal molar percent), the power factor P of Mg2Si0.8Ge0.2 reaches 4.4×10-4W/mK2 at 800K,obviously improved in comparison with the sample with no additive .</P>

The Components of Cacalia tangutica

Liu, Zhen-Ling,Tian, Xuan Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.7

Research on Vibration Saltation of the Transformer Core Caused by DC Bias of Based on Empirical Mode Decomposition

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.

Long non-coding RNA HOTAIR promotes hepatocellular carcinoma progression by regulating miR-526b-3p/DHX33 axis

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.

EXTENDED AHP METHOD FOR INTEGRATING QUANTITATIVE AND QUALITATIVE EVALUATIONS

Zhen LIU,Hikaru INOOKA 제어로봇시스템학회 1997 제어로봇시스템학회 국내학술대회 논문집 Vol.2 No.10