Unveiling of the energy storage mechanisms of multi -modified (Nb2O5@C)/rGO nanoarrays as anode for high voltage supercapacitors with formulated ionic liquid electrolytes

Zhang, Jiahe,Zhang, Haitao,Zhang, Yaqin,Zhang, Junwei,He, Hongyan,Zhang, Xixiang,Shim, Jae-Jin,Zhang, Suojiang Elsevier 2019 ELECTROCHIMICA ACTA Vol.313 No.-

AQUEOUS SYNTHESIS OF HIGH QUANTUM YIELD AND MONODISPERSED THIOL-CAPPED CdxZn1-xTe QUANTUM DOTS BASED ON ELECTROCHEMICAL METHOD

JUNWEI LI,YANG JIANG,YUGANG ZHANG,DI WU,ANQI LUO,ZHONGPING ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.2

A facile green approach has been developed to control the growth regime in the aqueous synthesis of CdxZn1-xTe semiconductor quantum dots (QDs) based on the electrochemistry method. The Low growth temperature and slow injection of Te precursor are used to prolong the diffusion controlled stage and thus suppress Ostwald ripening during the nanocrystal growth. The experimental results showed that a low concentration of Te precursor will definitely influence the growth procedure. The UV–visible absorption spectra, as well as transmission electron microscopy (TEM) shows the QDs a good monodispersity at any interval of the reaction procedure. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs have high crystallinity and cubic structure. The size and composition-dependent fluorescent emission wavelength of the resultant CdxZn1-xTe alloyed QDs can be tuned from 460 to 610 nm, and their photoluminescent quantum yield can reach up to 70%. Especially in the wavelength range of 510–578 nm, the overall PL QYs of the as-prepared CdxZn1-xTe QDs were above 50%. The current work suggests that electrochemical method is an attractive approach to the synthesis of high-quality II-VI ternary alloyed semiconductor QDs at large-scale with a prominent cost advantage.

Self-Assembly of Gold Nanoparticles on Gold Core-Induced Polypyrrole Nanohybrids for Electrochemical Sensor of Dopamine

Junwei Ding,Kai Zhang,Wei Xu,Zhiqiang Su 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.8

Gold core-induced polypyrrole nanohybrids (Au–PPyNHs) were successfully synthesized via in situ chemical oxidation polymerization of pyrrole molecules, and their structure was directly confirmed and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Furthermore, gold nanoparticles (AuNPs) were assembled onto the as-prepared Au–PPyNHs by electrostatic interaction to fabricate the nanohybrids of Au–PPyNH–Au. The created Au–PPyNH–Au nanohybrids was immobilized onto glassy carbon electrode and applied to construct dopamine (DA) sensor. We found that the fabricated sensor with Au–PPyNH–Au nanohybrids is highly specific probe for sensing DA. The Au–PPyNH–Au based DA sensor has a linear detection range from 1 µM to 0.321 mM and a detection limit of 0.32 µM.

Design and Optimization for Distributed Compress-and-Forward System based on Multi-Relay Network

( Junwei Bao ),( Dazhuan Xu ),( Hao Luo ),( Ruidan Zhang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.6

A novel distributed compress-and-forward (CF) system based on multi-relay network is presented. In this system, as the direct link between the source and destination is invalid due to some reasons, such as the limited power, special working environment, or even economic factors, relays are employed to receive analog signals and carry on distributed compressed encoding. Subsequently, the digital signals are transmitted to the destination via wireless channel. Moreover, a theoretical analysis for the system is provided by utilizing the Chief Executive Officer (CEO) theory and Shannon channel capacity theory, and the rate-distortion function as well as the connection between the transmission rate and the channel capacity are constructed. In addition, an optimal signal-to-noise ratio (SNR) -based power allocation method is proposed to maximize the quantization SNR under the limited total power. Simulation result shows that the proposed CF system outperforms the amplify-and-forward (AF) system versus the SNR performance.

Low‐complexity de‐mapping algorithms for 64‐APSK signals

Junwei Bao,Dazhuan Xu,Xiaofei Zhang,Hao Luo 한국전자통신연구원 2019 ETRI Journal Vol.41 No.3

Due to its high spectrum efficiency, 64‐amplitude phase‐shift keying (64‐APSK) is one of the primary technologies used in deep space communications and digital video broadcasting through satellite‐second generation. However, 64‐APSK suffers from considerable computational complexity because of the de‐mapping method that it employs. In this study, a low‐complexity de‐mapping method for (4 + 12 + 20 + 28) 64‐APSK is proposed in which we take full advantage of the symmetric characteristics of each symbol mapping. Moreover, we map the detected symbol to the first quadrant and then divide the region in this first quadrant into several partitions to simplify the formula. Theoretical analysis shows that the proposed method requires no operation of exponents and logarithms and involves only multiplication, addition, subtraction, and judgment. Simulation results validate that the time consumption is dramatically decreased with limited degradation of bit error rate performance.

Antifreeze protein detection using Rhodamine B as photoluminescence label in porous silicon

Hongyan Zhang,Zhenhong Jia,Xiaoyi Lv,Junwei Hou,Xiaojing Liu,Ji Ma,Jun Zhou 한국물리학회 2013 Current Applied Physics Vol.13 No.4

A novel method is demonstrated to detect Antifreeze proteins (AFPs) based on photoluminescence (PL)using porous silicon (PS) coated with silver as a substrate. Ag/PS substrate is obtained through immersion of PS in silver nitrate (AgNO3) solutions and is incubated with Rhodamine B (RB) as PL label. This substrate is easy to be fabricated and the pore size of PS is large enough for biological molecules to infiltrate, which is an ideal platform for biological molecule detection. Through functionalization used glutaraldehyde (GTA) and 4-(N-Maleimidomethyl) cyclohexane-1-carboxylicacid (Sulfo-SMCC) as crosslinkers separately, we test the role of the AFPs antibodies in selective capturing the AFPs antigen and explain the reason of the enhancement of PL intensity. The result shows a significant enhancement of the PL intensity of RB at around 590 nm due to the interaction of antibodyeantigen competitive binding with AFPs. Therefore, the PL corresponding to RB was selected to detect the target AFPs and the PL intensity of RB proportional to the AFPs concentration. The detection limit was found to be 1.65 mg/ml for AFPs when GTA was used as cross-linker, and the detection limit was 16.5 ng/ml with Sulfo-SMCC as cross-linker

Macrokinetic Model for Gluconobacter oxydans in 2-keto-L-gulonic Acid Mixed Culture

Zhixiong Zhang,Xinjie Zhu,Ping Xie,Junwei Sun,Jingqi Yuan 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.5

A set of kinetic models have been developed for the production of 2-keto-L-gulonic acid from L-sorbose by a mixed culture of Gluconobacter oxydans and Bacillus megaterium. A metabolic pathway is proposed for Gluconobacter oxydans, and a macrokinetic model has been developed for Gluconobacter oxydans, where the balances of some key metabolites, ATP and NADH are taken into account. An unstructured model is proposed for concomitant bacterium Bacillus megaterium. In the macrokinetic model and unstructured model, the mechanism of interaction between Gluconobacter oxydans and Bacillus megaterium is investigated and modeled. The specific substrate uptake rate and the specific growth rate obtained from the macrokinetic model are then coupled into a bioreactor model such that the relationship between the substrate feeding rate and the main state variables, such as the medium volume, the biomass concentrations, the substrate,and the is set up. A closed loop regulator model is introduced to approximate the induction of enzyme pool during lag phase after inoculation. Experimental results demonstrate that the model is able to describe 2-keto-Lgulonic acid fermentation process with reasonable accuracy.

基于UDMISS理论的中国移动医疗APP质量和用户满意度的关系研究

曹峻玮 ( Junwei Cao ),张贵花 ( Guihua Zhang ),刘栋 ( Dong Liu ) 사단법인 아시아문화학술원 2021 인문사회 21 Vol.12 No.3

移动医疗APP近几年在中国快速发展, 特别是随着COVID-19的爆发, 越来越多的人开始通过移动医疗APP在线获取医疗健康服务。本研究以移动医疗APP质量、用户对移动医疗APP熟悉程度为研究视角, 分析了影响用户满意度的因素。基于更新的信息系统成功理论(UDMISS), 考察已有的相关研究, 建立了包括3个维度、4个变量的研究模型, 提出了和研究相关的假设, 并对移动医疗APP用户进行问卷调查, 使用PLS-SEM以及SmartPls3.0对问卷数据进行分析, 对研究模型进行评价, 并且对提出的假设进行了验证。通过本研究期待为移动医疗APP企业的发展和营销提供理论基础和实践指导。 Mobile medical APP have developed rapidly in China in recent years, especially with the explosion of COVID-19, more and more people have started to access medical and health services online through mobile medical APP. This study analyzes the factors affecting user satisfaction by taking the quality of mHealth APP and users’ familiarity with mHealth APP as the research perspective. Based on the updated theory of information system success (UDMISS), the existing related studies were examined, a research model including 3 dimensions and 4 variables was established, hypotheses related to the study were proposed, and a questionnaire survey was conducted on mHealth APP users, and the questionnaire data were analyzed using PLS-SEM and SmartPls3.0 to evaluate the research model, and the proposed The hypotheses were validated. This study is expected to provide theoretical basis and practical guidance for the development and marketing of mobile medical APP companies.

Solution and Estimate to the Angular Velocity of INS Formed only by Linear Accelerometers

Wu Junwei,Liu Jinfeng,Zhang Yunan,Yuan Na 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.1 No.-

At present, most efforts tend to develop a INS which is only based linear accelerometers, because of the low cost micro-machining gyroscopes lack of the accuracy needed for precise navigation application and possible achieving the required levels of precise for micro-machining accelerometer. Although it was known in theory that a minimum of six accelerometers are required for a complete description of a rigid body motion, and any configuration of six accelerometers (except for a “measure zero” set of six-accelero-meter schemes) will work. Studies on the feasible configuration of GF-INS indicate that the errors of angular velocity resolved from the six accelerometers scheme are diverged with time or have multi solutions. The angular velocity errors are induced by the biases together with the position vectors of the accelerometers, therefore, in order to treat with the problem just mentioned, researchers have been doing many efforts, such as the extra three accelerometers or the magnetometers may be taken as the reference information, the extended Kalman filter (EKF) involved to make the angular velocity errors bound and be estimated, and so on. In this paper, the typical configurations of GF-INS are introduced; for each type GF-INS described, the solutions to the angular velocity and the specific force are derived and the characteristic is indicated; one of the corresponding extend Kalman filters are introduced to estimate the angular errors; parts of the simulation results are presented to verify the validity of the equations of angular velocity and specific force and the performance of extend Kalman filter.

在线教育平台游戏化元素对持续使用的影响机制研究: 基于S-O-R视角

张贵花 ( Guihua Zhang ),曹峻玮 ( Junwei Cao ),刘栋 ( Dong Liu ) 사단법인 아시아문화학술원 2021 인문사회 21 Vol.12 No.6

近几年在线教育快速发展, 特别是随着COVID-19的爆发, 越来越多的⼈开始通过在线教育平台进行学习。本研究从在线教育平台中的游戏元素切入, 分析影响⽤户持续使用的因素。基于刺激机体反应框架(S-O-R Framework), 在先行研究的基础上, 提出假设, 建⽴研究模型。对在线教育⽤户进⾏问卷调查后, 使⽤PLS-SEM以及SmartPls3.0进行假设验证。研究结果表明游戏化元素对在线教育用户的享受和持续使用有显著的积极影响, 同时发现用户的适应性显著的正向调节了游戏化元素和用户享受之间的关系。研究指出, 为了更好地激发用户兴趣, 在线教育企业应结合课程内容和用户特点, 精心设计游戏化体验。 Online education is developing rapidly in recent years. Especially with the outbreak of COVID-19, more and more people begin to learn through online education platform. This research starts with the elements of gamification in online education and analyzes the factors affecting users’ continuous use. Based on the Stimulus-Organism-Response Framework (SOR) and the previous researches, the hypothesis was put forward, and the research model was established. After the questionnaire survey of online education users, PLS-SEM and smartpls3.0 were used to verify the hypothesis. The research results show that gamification elements have a significant positive impact on the enjoyment and continuous use of online education users, and it is also found that users’ adaptability significantly positively regulates the relationship between gamification elements and users’ enjoyment. Research points out that in order to better stimulate user interest, online education companies should carefully design gamification experience in combination with course content and user characteristics.