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        • KCI등재SCOPUS

          Synthesis of bi-functionalized ionic liquid - mesoporous alumina composite material and its CO2 capture capacity

          Liwei,Sun,Shaokun,Tang 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.10

          Bi-functionalized ionic liquid (IL) - mesoporous alumina (MA) composite material was synthesized and used for CO2 capture. Ordered mesoporous alumina was synthesized by self-assembly method with aluminum isopropoxide as aluminum source. Then bi-functionalized ionic liquid 1-methoxyethyl-3-methyl imidazole glycinate ([MOEmim][Gly]) was immobilized on mesoporous alumina by ultrasonic-assisted impregnation method. Ordered mesostructure of alumina keeps well in the composite material. Compared with bi-functionalized ionic liquid, thermal stability of the composite material greatly improved. Finally, CO2 capture capacity of IL-MA composite material was studied under different temperatures. On the basis of both capture capacity and capture rate, 40 oC is the optimal temperature. The capture capacity is 1.42mol·mol IL−1 - equivalent to 144mg·g sorbent−1, which is higher than IL or MA alone. Furthermore, the capture capacity of composite material almost maintains constant after eight capture-regeneration cycles.

        • KCI등재SCOPUS

          Mechanism and kinetics of esterification of adipic acid and ethylene glycol by tetrabutyl titanate catalyst

          Liwei,Chen,Jumei,Xu,Weilan,Xue,Zuoxiang,Zeng 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.1

          An eight-step mechanism of esterification reaction between adipic acid (AA) and ethylene glycol (EG) catalyzed by tetrabutyl titanate [Ti(OBu)4] was studied in detail. The kinetic data for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)4] were measured in the temperature range of 403 K-433 K. A second- order kinetic model was established, and the model parameters were obtained through an optimization procedure by minimizing the value differences between the simulated component concentrations in the reaction system with the experimental ones. The results demonstrate that the model is suitable for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)4]. Furthermore, the esterification reaction rate increases with the increase of reaction temperature, concentration of catalyst and the initial reactant ratio of EG to AA.

        • KCI등재SCOPUS

          CFD study on hydraulic performance of subsurface flow constructed wetland: Effect of distribution and catchment area

          Liwei,Fan,Reti,Hai,Zexiang,Lu 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.5

          A subsurface flow constructed wetland (SSFW) was simulated by using a commercial computational fluid dynamic (CFD) code (Fluent 6.22, Fluent Inc.). The liquid residence time distribution in the SSFW was obtained by the particle trajectory model. The simulation confirmed that the effect of the distribution and/or catchment area on the hydraulic efficiency is significant. An inappropriate horizontal distribution and/or catchment area can result in poor hydraulic efficiency. The hydraulic efficiency of the SSFW with the vertical distribution and/or catchment area can be kept at a high level (above 0.898). The design of the vertical distribution and/or catchment area in the SSFW is better than that of the horizontal. From the point of view of the engineering design, a small dimension distribution and/or catchment area in the SSFW is advisable, which maintains a considerable hydraulic efficiency of the SSFW (above 0.840), but also benefits the increase of the purge area. A subsurface flow constructed wetland (SSFW) was simulated by using a commercial computational fluid dynamic (CFD) code (Fluent 6.22, Fluent Inc.). The liquid residence time distribution in the SSFW was obtained by the particle trajectory model. The simulation confirmed that the effect of the distribution and/or catchment area on the hydraulic efficiency is significant. An inappropriate horizontal distribution and/or catchment area can result in poor hydraulic efficiency. The hydraulic efficiency of the SSFW with the vertical distribution and/or catchment area can be kept at a high level (above 0.898). The design of the vertical distribution and/or catchment area in the SSFW is better than that of the horizontal. From the point of view of the engineering design, a small dimension distribution and/or catchment area in the SSFW is advisable, which maintains a considerable hydraulic efficiency of the SSFW (above 0.840), but also benefits the increase of the purge area.

        • KCI등재SCOPUS

          DISTRIBUTED FORMATION CONTROL OF HOMOGENEOUS VEHICLE PLATOON CONSIDERING VEHICLE DYNAMICS

          Liwei,Xu,Weichao,Zhuang,Guodong,Yin,Chentong,Bian 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.6

          Vehicle dynamics plays a significant role on the formation of a vehicle platoon, especially at high speed condition. This paper proposes a distributed platoon formation framework for homogeneous autonomous vehicles which takes the vehicle dynamics into consideration. The boundaries of vehicle stability are firstly calculated by considering both lateral dynamics and actuator saturation. By combining the stability boundaries with multi-objective flocking (MOF) algorithm, a distributed formation controller is designed, which can form the vehicle platoon with high cruising speed steadily and rapidly. In addition, a low-level tracking controller is proposed to constitute a hierarchical control architecture which can achieve stable and accurate formation of platoon. Simulation results show the proposed platoon formation controller achieves safe, stable and rapid platoon formation than the traditional MOF-based formation controller which does not consider the vehicle dynamics.

        • KCI등재SCOPUS

          Enhanced Catalytic Ability of Candida rugosa Lipase Immobilized on Pore-enlarged Hollow Silica Microspheres and Cross-linked by Modified Dextran in Both Aqueous and Non-aqueous Phases

          Liwei,Ren,Honghua,Jia,Min,Yu,Wenzhong,Shen,Hua,Zhou,Ping,Wei 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.5

          Candida rugosa lipase (CRL) is one of the most widely used lipases. To enhance the catalytic abilities of CRL in both aqueous and non-aqueous phases, hollow silica microspheres (HSMSs) with a pore size of 18.07 nm were used as an immobilization support, and aldehydecontaining dextrans were employed to further cross-link the adsorbed CRL. In the experimental ranges examined,the loading amount of lipase linearly increased to 171 ±3.4 mgprotein/gsupport with the CRL concentration and all the adsorption equilibriums were reached within 30 min. After simple cross-linking, the tolerance to pH 4.0 ~ 8.0 as well as the thermal stability of immobilized CRL at 40 ~ 80oC were both substantially increased, and 82 ± 2.1% activity remaining after the sixth reuse. The immobilized CRL was successfully applied to the resolution of racemic ibuprofen in non-aqueous phase. The initial reaction rate increased by 1.4- and 3.6-fold compared with the rates of adsorbed and native lipases, respectively. Furthermore, the R-ibuprofen was obtained at ee > 93%, and the enantiomeric ratio reached E > 140 at the conversion of 50 ± 1.5% within 48 h.

        • KCI등재SCOPUS

          Multilinear Calderon-Zygmund operators and their commutators on central Morrey spaces with variable exponent

          Liwei,Wang 대한수학회 2020 대한수학회보 Vol.57 No.6

          In this paper, we establish the boundedness of the $m$-linear Calder\'{o}n-Zygmund operators on product of central Morrey spaces with variable exponent. The corresponding boundedness properties of their commutators with $\lambda$-central {\rm BMO} symbols are also considered. Finally, we prove that the multilinear commutators of Calder\'{o}n-Zygmund singular integrals introduced by P\'{e}rez and Trujillo-Gonz\'{a}lez are bounded on central Morrey spaces with variable exponent. Our results improve and generalize some previous classical results to the variable exponent setting.

        • KCI등재

          Synthesis of Au Nanoparticles Functionalized 1D α-MoO3 Nanobelts and Their Gas Sensing Properties

          Liwei,Wang,Shaopeng,Wang,Hao,Fu,Yinghui,Wang,Kefu,Yu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.10

          A novel sensor material of Au nanoparticles (NPs) functionalized 1D α-MoO3 nanobelts (NBs) was fabricated by a facile lysine-assisted approach. The obtained Au/α-MoO3 product was characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray (EDX), and X-ray photoelectron spectra (XPS). Then, in order to investigate the gas sensing performances of our samples, a comparative gas sensing study was carried out on both the α-MoO3 NBs before and after Au NPs decoration by using ethanol vapor as the molecular probe. The results turned out that, after the functionalization of Au NPs, the sensor exhibited improved gas-sensing characteristics than the pure α-MoO3, such as response and recovery time, optimal operating temperature (OT) and excellent selectivity. Take for example 200 ppm of ethanol, the response/ recovery times were 34 s/43 s and 5.7 s/10.5 s, respectively, while the optimal operating temperature (OT) was lower to 200 ℃ rather than 250 ℃. Besides, the functionalized sensor showed a higher response to ethanol at 200 ℃, and response was 1.6 times higher than the pure MoO3. The mechanism of such improved sensing properties was interpreted, which might be attributed to the spillover effect of Au NPs and the electronic metal-support interaction.

        • An Empirical Research on the Influencing Factors of Mobile Commerce Diffusion in China

          Liwei,Li 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.6

          This paper analyzes the factors affecting China's mobile commerce diffusion at the infant stage and taking-off stage using the data of 31 provinces of China in the years of 2009 and 2012 respectively based on the partial least square regression method. The results of the analysis indicate that fixed broadband penetration rate, GDP per capita and internet penetration rate, urbanization level are the top 4 factors at the infant stage of mobile commerce diffusion, while internet penetration rate,2G mobile penetration rate, income and fixed broadband penetration are the top 4 factors at the taking-off stage of mobile commerce. The findings provide researchers and policy-makers systematic insights into the role of different factors in mobile commerce diffusion at a country level and over time.

        • Online consumer ratings/reviews (OCR), click-through rate (CTR) and the boomerang effect of online hotel booking

          ( Liwei Hsu ), ( Yi Ting Huang ), ( Ching Wen Wang ) 한국관광학회 2018 한국관광학회 국제학술발표대회 Vol.84 No.-

          Travelers of today greatly rely on the Internet to book hotels wherein they are able to use online consumer ratings/reviews as references to make their decision if they are not familiar with the hotel. However, customers may suspect that positive reviews and ratings are possibly being manipulated by business owners which may lead to the occurrence of Boomerang Effect. This research recruited 54 students (n = 54) from a national university in southern Taiwan. The participants were asked to search for information about hotels in Taipei for their next trip on an online hotel booking platform. Number of stars and positive as well as negative reviews of the hotel they selected were recorded for further analyses which would be cross-examined with the Click-Through Rates (CTR) of each hotels. Results of this research show that the number of star a hotel is rated has significantly high correlation with its CTR. Furthermore, both numbers of positive and negative reviews are significantly correlated to CTR; nevertheless, number of positive reviews is close to highly correlated to CTR whereas number of negative reviews is moderately correlated to CTR. Lastly, Boomerang Effect was not discovered in the process of participants' making decision through online hotel booking.

        • Research on Influence of Multimedia Network Teaching Platform and Effective Interaction on Physical Education Curriculum Based on Smart Classroom

          Liwei,SUN 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.11

          With the development of computer information technology and multimedia Internet technology, human beings have entered a new era of knowledge and network. Education information construction is an important way for the modernization of education, in this paper, the author research on influence of multimedia network teaching platform and effective interaction on physical education curriculum. For the necessity of multimedia and network assisted instruction, 68.57% teachers think that multimedia teaching is very important, and it is necessary means of physical education teaching. Multimedia network teaching platform can also integrate the latest sports information resources, students can watch all kinds of large-scale sports events by online video.

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