Experimental study on multi-level overtopping wave energy convertor under regular wave conditions

Liu, Zhen,Han, Zhi,Shi, Hongda,Yang, Wanchang The Society of Naval Architects of Korea 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.

Controlled synthesis of transition metal/conducting polymer nanocomposites

Liu, Zhen,Liu, Yang,Zhang, Lin,Poyraz, Selcuk,Lu, Ning,Kim, Moon,Smith, James,Wang, Xiaolong,Yu, Yajiao,Zhang, Xinyu IOP Pub 2012 Nanotechnology Vol.23 No.33

<P>A novel displacement reaction has been observed to occur between conducting polymers (CP) and metal salts which can be used to fabricate nanostructured CP–metal composites in a one-pot manner. Vanadium pentoxide (V <SUB>2</SUB>O<SUB>5</SUB>) nanofiber is used during the synthesis as the reactive seeds to induce the nanofibril CP–metal network formation. The CP–metal nanocomposites exhibit excellent sensory properties for hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>) detection, where both high sensitivity and a low detection limit can be obtained. The sensory performance of the CP–metal composite can be further enhanced by a facile microwave treatment. It is believed that the CP–metal nanofibril network can be converted to a carbon–metal network by a microwave-induced carbonization process and result in the sensory enhancement. </P>

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.

휴대용 게임기 구매의도에 영향을 미치는 요인에 관한 한중 비교연구

LIU ZHEN,강유리,박철 한국경영정보학회 2010 한국경영정보학회 학술대회논문집 Vol.2010 No.1

첨단제품의 하나인 휴대용 게임기는 언제 어디서나 멀티미디어 콘텐츠를 활용할 수 있는 유비쿼터스를 기반으로 급속히 발전하고 있다. 본 연구에서는 휴대용 게임기를 대상으로 소비자의 구매의도에 영향을 미치는 요인이 무엇인지 한국과 중국의 소비자를 비교하였다. 사용된 변수는 크게 휴대용게임기 혜택요인과 소비자요인이었다. 그 결과, 한국과 중국에서 모두 시간활용성, 유행추구성, 소비자혁신성, 가격민감성, 그리고 주관적 규범은 게임기 구매의도에 유의한 영향을 미치는 것으로 나타났다. 그러나 조작편리성, 인지된 즐거움, 진부화 위험 등이 게임기 구매의도에 미치는 영향은 중국과 한국에서 유의한 차이가 나타났다. 본 연구 결과의 이론적 시사점으로는 향후 국가 간 휴대용 게임기의 구매의도에 관한 연구를 하는데 도움이 될 것이고, 실무적 시사점으로는 휴대용 게임기를 비롯한 첨단제품 사용에 관한 중국 소비자들의 구매의도를 파악하는데 도움이 될 것이다.

试论<秋声赋>的文体⋅主题思想与艺术价值

LIU ZHEN,이석형 한국중국어문학회 2018 中國文學 Vol.95 No.-

Ode to the Sound of Autumn, as a new emerging literature form, is the representative work of Wenfu. Inspired by Ouyang Xiu’s innovative consciousness and practice, as well as its superb language performance and amazing artistic value, Ode to the Sound of Autumn has exerted far-reaching influence in the history of Chinese literature. The author thinks that “Beiqiu Tanlao” is more consistent with the traditional cultural tendency of literati in the Song dynasty, which is also the theme of Ode to the Sound of Autumn. It is through this theme that Ouyang xiu expresses a generation of great literati’s observation and understanding of the universe, which reflects their emotions to life standing the new height of life. Moreover, Ode to the Sound of Autumn, not only enjoys great reputation in the history of Wenfu, but also is a classic prose in Chinese literature, it relies on beauty of image, sense and form, by using rhyme, level and oblique tones, rhythm, word, sentence, allusion, vividly show us its unique Chinese aesthetic characteristics from ancient times to the present. <秋聲賦>는 文賦의 대표 작품으로 작가 歐陽脩의 창신 의식과 실천적 탐구 정신이 반영되어 있다. <추성부>는 뛰어난 표현 수법과 놀라운 예술적 매력을 가지고 있어 이후 등장하는 賦體의 창작에 많은 영향을 끼친 것으로 평가된다. 필자는 <추성부>의 주제에 대하여 역대 비평가들의 평가를 통해 <추성부>의 문학사적 위상에 대해 재고찰해보았다. 동시에 다각도적인 분석을 통하여 그 중 “悲秋歎”가 송대 문인의 품격에 잘 어울리는 전통 문화의 경향이라고 판단하였다. 이러한 주제의식은 우주 만물에 대한 문인으로서의 관찰과 깨달음이 반영된 것이며, 작가 자신이 인생에서 느꼈던 생명에 대한 감개와 사고의 표현이라 할 수 있다. <추성부>는 부의 역사에서 최초의 문부라는 명성을 지니고 있을 뿐만 아니라 후세에까지 그 고아한 필치를 길이 남긴 美文이기도 하다. 그것의 신운미, 의경미, 그리고 체식미는 용운⋅평측⋅리듬⋅연자⋅조구⋅용전 등의 수법을 통해 <추성부>에서 형상화되었다. <추성부>는 오랜 시간이 흘렀어도 그 독창성을 인정받으며 지금까지 문언 미학의 특질을 잘 나타낸 작품으로 평가된다.

Controlled synthesis and luminescence properties of doped NaLa(WO4)2 microstructures

Yunhua Han,Yan Wang,Shaohua Huang,Fan-Long Jin,Shili Gai,Na Niu,Liuzhen Wang,Piaoping Yang 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-

In this work, well-defined NaLa(WO4)2microstructures were prepared by a facile hydrothermal processin the presence of oleylamine and oleic acid as a mixed surfactant. The phase, morphology, size andluminescence properties were well characterized by means of X-ray diffraction (XRD), scanning electronmicroscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and decaytime, respectively. The results reveal that the morphology and size of the as-synthesized samples can betuned by altering the reaction time and the amounts of oleic acid. A possible formation mechanism oftetragonal NaLa(WO4)2 is proposed on the basis of oleic acid amount-dependent experiments. Uponultraviolet (UV) excitation, NaLa(WO4)2:Eu3+ and NaLa(WO4)2:Tb3+ exhibit the characteristic downconversionemissions of Eu3+ and Tb3+. Yb3+/Er3+ and Yb3+/Tm3+ co-doped NaLa(WO4)2 samples showstrong green (Er3+, 4S3/2, 2H11/2!4I15/2) and blue (Tm3+, 1G4!3H6) up-conversion emission under980 nm laser diode excitation. Upconversion emission mechanisms of NaLa(WO4)2:Ln (Ln = Yb/Er, Yb/Tm) are also presented based on the emission spectra and the plot of luminescence intensity to pumppower. It should be noted that the intensity of the upconversion emissions can be dramatically enhancedcompared with sodium free tungstates, which can be attributed to the charge compensation and meansthe introduction of Na+ ions in WO42 causes less distortion in the crystal structure.