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Preparation and characterization of 3-dimensionally ordered macroporous SiC

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Science China(Technological Sciences) 2006年第1期49卷 1-9页

作者： kim dong-pyo Department of Fine Chemical Engineering and Chemistry of Chungnam National University Taejon 305-764 South Korea

Three-dimensionally (3D) long range ordered macroporous SiC ceramics were prepared through infiltrating polymethylsilane (PMS) into the 3D ordered sacrificial silica template, pyrolysis and the template removal. It was found that the pore size (84―658 nm), BET surface area (299.44―584.64 m2/g) and micropore volume (0.25―0.64 cm3/g) of the achieved porous SiC can be tailored by utilizing different sizes silica sphere templates. There exist three kinds of pores in the porous ceramics: sphere inversed pores, windows and mesopores (2―5 nm). The sphere inversed pores were packed as hcp structure and three dimensionally penetrated through the windows, and the mesopores endowed the porous ceramics surprising high BET surface areas and micropore volumes.

关键词： three-dimensionally ordered materials, templated technique, preceramic polymer conversion technique, SiC ceramic.

Manifolding active sites and in situ/operando electrochemical-Raman spectroscopic studies of single-metal nanoparticle-decorated CuO nanorods in furfural biomass valorization to H_(2) and 2-furoic acid

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Journal of Energy Chemistry 2023年第9期84卷 50-61页

作者： Jiwon kim Talshyn Begildayeva Jayaraman Theerthagiri Cheol Joo Moon Ahreum Min Seung Jun Lee Gyeong-Ah kim myong Yong Choi Department of Chemistry(BK21 FOUR) Research Institute of Natural SciencesGyeongsang National UniversityJinju 52828Republic of Korea Core-Facility Center for Photochemistry&Nanomaterials Gyeongsang National UniversityJinju 52828Republic of Korea Department of IT-Energy Convergence(BK21 FOUR) Korea National University of TransportationChungju 27469Republic of Korea

Here,CuO nanorods fabricated via pulsed laser ablation in liquids were decorated with Ir,Pd,and Ru NPs(loading~7 wt%) through pulsed laser irradiation in the liquids *** resulting NPs-decorated CuO nanorods were characterized spectroscopically and employed as multifunctional electrocatalysts in OER,HER,and the furfural oxidation reactions(FOR).Ir-CuO nanorods afford the lowest overpotential of~345 mV(HER) and 414 mV(OER) at 10 mA cm^(-2),provide the highest 2-furoic acid yield(~10.85 mM) with 64.9% selectivity,and the best Faradaic efficiency~72.7% in 2 h of FOR at 1.58 V(***).In situ electrochemical-Raman analysis of the Ir-CuO detects the formation of the crucial intermediates,such as Cu(Ⅲ)-oxide,Cu(OH)_(2),and Ir_x(OH)_y,on the electrode-electrolyte surface,which act as a promoter for HER and *** Ir-CuO ‖ Ir-CuO in a coupled HER and FOR-electrolyzer operates at~200 mV lower voltage,compared with the conventional electrolyzer and embodies the dual advantage of energy-saving H_(2) and 2-furoic acid production.

关键词： Single-metal nanoparticle-decorated CuO nanorods Pulsed laser ablation and irradiation in liquids Furfural oxidation reaction Hydrogen evolution reaction Energy-saving H_(2)production 2-Furoic acid

Dragonfly Interaction Algorithm for Optimization of Queuing Delay in Industrial Wireless Networks

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Journal of Bionic Engineering 2024年第1期21卷 447-485页

作者： Sanjay Bhardwaj Da-Hye kim dong-Seong kim Department of IT Convergence Engineering ICT Convergence Research CenterKumoh National Institute of TechnologyGumiSouth Korea

In industrial wireless networks,data transmitted from source to destination are highly *** often leads to the queuing of the data,and poor management of the queued data results in excessive delays,increased energy consumption,and packet ***,a nature-inspired-based Dragonfly Interaction Optimization Algorithm(DMOA)is proposed for optimization of the queue delay in industrial wireless *** term“interaction”herein used is the characterization of the“flying movement”of the dragonfly towards damselflies(female dragonflies)for *** a result,interaction is represented as the flow of transmitted data packets,or traffic,from the source to the base *** includes each and every feature of dragonfly movement as well as awareness of the rival dragonflies,predators,and damselflies for the desired optimization of the queue *** features are juxtaposed as noise and interference,which are further used in the calculation of industrial wireless metrics:latency,error rate(reliability),throughput,energy efficiency,and fairness for the optimization of the queue *** analysis,convergence analysis,the Wilcoxon test,the Friedman test,and the classical as well as the 2014 IEEE Congress of Evolutionary Computation(CEC)on the benchmark functions are also used for the evaluation of DMOA in terms of its robustness and *** results demonstrate the robustness of the proposed algorithm for both classical and benchmarking functions of the IEEE CEC ***,the accuracy and efficacy of DMOA were demonstrated by means of the convergence rate,Wilcoxon testing,and ***,fairness using Jain’s index in queue delay optimization in terms of throughput and latency,along with computational complexity,is also evaluated and compared with other *** results show that DMOA exceeds other bio-inspired optimization algorithms in terms of fairness in queue delay management and average packet *** proposed a

关键词： Dragonfly Damselfly Interaction Queuing delay Optimization Industrial wireless networks

Simple reactor for the synthesis of silver nanoparticles with the assistance of ethanol by gas-liquid discharge plasma

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Plasma Science and Technology 2019年第4期21卷 34-43页

作者： Pan LU dong-Wook kim dong-Wha PARK Department of Chemistry and Chemical Engineering Inha University100 Inha-Ro.Michuhol-guIncheon 22212Republic of Korea Regional Innovation Center for Environmental Technology of Thermal Plasma(RIC-ETTP: Inha University100 Inha-RoMichuhol-gu.Incheon 22212.Republic of Korea

Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic *** addition to the development of the power supply,improving the reactor is also one of the main strategies to enhanee the *** this study,a simple reactor for the gas-liquid discharge plasma induced by argon gas was applied to synthesize silver nanopailicles from silver nitrate(AgNO3)in *** AC power supply with a peak voltage of 3.5 kV was *** frequency and on-time were set to 50 kHz and 2.5“s,*** oscilloscope showed that the rising time was approximately 2“*** ethanol was used as the source for the reactive reducing *** more additional comp on ents existed in the solution during the discharge and neither of the electrodes was in contact with the treated *** temperature in creased by 10°C within 1 min without a cooling *** was the main impurity and was expected to be produced from the decomposition of the organics under the *** elevated temperature decreased the organic by-products by evaporation and could also decrease the production of *** electron microscopy showed that the spherical silver nanoparticles with a size of approximately 10 nm were synthesized with a crystal structure and that a low concentration of ethanol prefers the production of the mono-dispersed colloid.

关键词： silver nanoparticles synthesis nonthermal plasma ethanol reduction gas-liquid discharge

Synthesis and Characterization of Photosensitive Poly(imide sulfonates) for Fuel Cell Application

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Journal of Wuhan University of Technology(Materials Science) 2013年第4期28卷 635-642页

作者：文璞山 LIU Hui kim Jae Hoon LI Xiangdan LEE myong-Hoon Department of Polymer Science and Technology Research Center for Advanced Materials Development Chonbuk National University College of Chemistry and Material Science South-Central University for Nationalities The Graduate School of Flexible and Printable Electronics Chonbuk National University

The novel sulfonated polyimide membranes were successfully synthesized by thermal imidization with monomers of 4,4＇-（hexafluoroisopropylidene）diphthalic anhydride （6FDA）, 4,4＇-diamino- diphenyl ether-2,2＇-disulfonic acid （SODA） and 3,3 ＇-diaminochalcone （3DAC）. Photosensitive chalcone moiety was introduced to the main chain of copolymers, and the photocrosslinking of resulting copolymer in aqueous electrolyte was attempted. A series of sulfonated copolyimide precursors containing chalcone functional groups in the main chain were prepared with different sulfonation degrees by controlling the molar ratio of SODA, 6FDA and 3DAC. The polymer membranes were prepared from these sulfonated aromatic precursors by solution casting and subsequent thermal imidization. The crosslinking with UV irradiation was attempted in the presence or absence of distilled water. The characterizations of the resulting membrane such as the ion-exchange capacity, water absorption and ionic conductivity were performed with respect to the copolymer compositions and the photocrosslinking conditions.

关键词： sulfonated polyimide photosensitive chalcone polymer electrolyte membrane fuel cell

Chrysanthemum indicum ethanol extract attenuates hepatic stellate cell activation in vitro and thioacetamide-induced hepatofibrosis in rats

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Asian Pacific Journal of Tropical Biomedicine 2021年第11期11卷 500-509页

作者： Yun-Jin Chae Sushruta Koppula myong-Ki kim Tony Yoon Mindong Song Department of Applied Life Science Graduate School of Konkuk University268 Chungwon-daeroChungju-siChungbuk27478Republic of Korea Department of Biotechnology College of Biomedical and Health SciencesKonkuk University268 Chungwon-daeroChungju-siChungbuk27478Republic of Korea Research Institute and College of Biomedical&Health Science Konkuk University268 Chungwon-daeroChungju-siChungbuk27478Republic of Korea Scholar Foxtrot Co. LTD501SinGwan-dong 5FJongam-ro 36-gilSeongbuk-guSeoul02796Republic of Korea Department of Food Science and Engineering Seowon UniversityCheongjuChungbuk 28674Republic of Korea Food One Corp 127Sincheoksandan 5-roDeoksan-eupJincheon-gunChungbuk 27850Republic of Korea

Objective:To investigate the antifibrotic effects of Chrysanthemum indicum ethanol extract(CIEE)against activated hepatic stellate cells(HSC)and thioacetamide(TAA)-induced hepatofibrosis in ***:Cell viability and proliferation of HSC-T6 cells were measured using MTT *** HSCs were used to study ***(200 mg/kg)was used to induced hepatic fibrosis in ***(100 and 500 mg/kg)and silymarin(50 mg/kg)were administered *** functions including alanine transaminase,aspartate transaminase,glutathione,and hydroxyproline levels were measured using commercial *** sections and fibrotic biomarker expression were measured using hematoxylin and eosin staining and real-time polymerase chain ***:In vitro study revealed that CIEE(0.1,0.25,and 0.5 mg/mL)inhibited the proliferation of activated HSCs exposed to transforming growth factor(TGF)-β and restored the activated primary HSC *** in vivo studies,TAA-induced increase in liver/body weight ratio(5.46±0.26)was significantly reduced(4.13±0.22)by CIEE(P<0.05 at 500 mg/kg).CIEE(100 and 500 mg/kg)improved the liver functions by significantly attenuating changes in alanine transaminase,aspartate transaminase,glutathione,and hydroxyproline levels(P<0.05).Further,CIEE(100 and 500 mg/kg)ameliorated the histological changes in liver tissue and TGF-β expression significantly(P<0.05)in TAA-induced ***:CIEE significantly protects against TAA-induced liver damage in rats and can be used in the treatment of liver fibrosis.

关键词： Chrysanthemum indicum Fibrosis Hepatoprotective Hydroxyproline Thioacetamide

Analysis of the Oscillatory Flows of Multiple Shock Waves in a Constant Area Duct

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Journal of Thermal Science 2024年第3期33卷 794-806页

作者： K JAMES Jintu kim Heuy dong Department of Mechanical Engineering Andong National UniversityAndong36729Republic of Korea CAD-IT Korea Co. Ltd.Seoul08591Republic of Korea

The oscillatory response of multiple shock waves to downstream perturbations in a supersonic flow is studied numerically in a rectangular *** shock waves are formed inside the duct at a shock Mach number of *** duct has an exit height of H,and the effect of duct resonance on multiple shock oscillations is investigated by attaching exit ducts of lengths 0H,50H,and *** downstream disturbance frequency varied from 10 Hz to 200 Hz to explore the oscillation characteristics of the multiple shock *** oscillatory response of shock waves under self-excited and forced oscillation conditions are analyzed in terms of wall static pressure,shock train leading-edge location,shock train length,and the size of the separation *** extent of the initial shock location increases with an increase in exit duct length for the self-excited oscillation *** analysis of the shock train leading edge and the spectral analysis of wall static pressure variations are *** variation in the shock train length is analyzed using the pressure ratio method for self-excited as well as forced *** RMS amplitude of the normalized shock train length(ζ_(ST))increases with an increase in the exit duct length for the self-excited oscillation *** the downstream perturbation frequency is increased,ζ_(ST)is decreased for exit duct *** all exit duct designs and downstream forcing frequencies,the size of the separation bubble grows and shrinks during the shock oscillations,demonstrating the dependence on duct resonance and forced oscillations.

关键词： shock train downstream disturbance supersonic flow shock wave boundary layer interaction duct resonance flow separation

The Effect of Diffuser Angle on the Discharge Coefficient of a Miniature Critical Nozzle

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Journal of Thermal Science 2010年第3期19卷 222-227页

作者： Jae Hyung kim Heuy dong kim Toshiaki Setoguchi School of Mechanical Engineering Andong National UniversityAndong760-749Korea Department of Mechanical Engineering Saga University1HonjoSagaJapan

Many researches on critical nozzles have been performed to accurately measure the mass flow rate of gas flow,and to standardize the performance as a flow ***,much interest is being paid on the measurement of very small mass flow rate in industry fields such as MEMS ***,the design and performance data of the critical nozzles obtained so far have been applied mainly to the critical nozzles with comparatively large diameters,and the works available on miniature critical nozzles are *** the present study,a computational fluid dynamics method has been applied to investigate the influence of the diffuser angle on discharge coefficient of the miniature critical *** computations,the throat diameter of critical nozzle is varied from 0.2 mm to 5.0 mm and the diffuser angle is changed from 2 deg to 8 *** computational results are validated with some experimental data *** results show that the present computational results predict appropriately the discharge coefficient of the gas flows through miniature critical *** is known that the discharge coefficient is considerably influenced by the diffuser angle,as the throat diameter of nozzle becomes small below a certain *** implies that the miniature critical nozzles should be carefully designed.

关键词： Compressible Flow Critical Nozzle Compressible Flow Discharge Coefficient Diffuser Configuration Reynolds Number

Supersonic Cavity Based Combustion with Kerosene/Hydrogen Fuel

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Journal of Thermal Science 2015年第2期24卷 164-172页

作者： Rajarshi Das Jeong Soo kim Heuy dong kim Department of Mechanical Engineering Andong National University School of Mechanical Engineering Pukyong National University

A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Math number of 2.08 has been probed. The investigation has been carried out in a two dimension- al numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test sec- tion shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.

关键词： Scramjet fuel-air mixing kerosene hydrogen equivalence ratio