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Ni, Co-double hydroxide wire structures with controllable voids for electrodes of energy-storage devices

Journal of Materials Science & Technology 2020年第20期52卷 126-135页

作者： Jin Kyu Kim Chang soo Lee Jae Hun lee Jung Tae Park Jong Hak Kim Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department of Chemical Engineering Konkuk University120 Neungdong-roGwangjin-guSeoul 05029Republic of Korea

We re port the facile synthesis of Ni,Co-double hydroxide wire(NCHW)-based electrodes directly grown on a conductive substrate via a hydrothermal process.Various NCHW nanostructures were grown on Ni foam,and the growth was controlled using different compositions of solvents(ethanol and water).With increasing volume ratio of ethanol to water,the density of the wires decreased,and the spatial voids between the wires increased.The formation of large empty spaces improved the electrochemical performance because the exposure of a large surface area of the structure to the electrolyte resulted in a large number of active sites and facile electrolyte penetration into the structure.The different NCHW structures were ascribed to the pivotal role of the solvent in the urea hydrolysis;the solvent triggered the formation of hydroxides during the hydrothermal synthesis.The electrochemical performance of the NCHW electrodes was investigated via galvanostatic charge/discha rge tests,cyclic voltammetry,and electrochemical impedance spectroscopy.The highest specific capacitance was 1694.7 m F/cm^2 at 2 mA/cm^2,with excellent capacitance retention of 81.5% after 5000 cycles.The superior electrochemical performance of the NCHW electrodes is attributed to the large number of active sites and facile electrolyte diffusion into the structure,due to the well-organized structure with an optimized density of nanowires and large voids between the wires.

关键词： Ni,Co-double hydroxide Nanowire Electrode Energy-storage device Supercapacitor

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Parameterization of below-cloud scavenging for polydisperse fine mode aerosols as a function of rain intensity

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Journal of Environmental Sciences 2023年第10期132卷 43-55页

作者： chang Hoon Jung Hyung-Min lee Dasom Park Young Jun Yoon Yongjoo Choi Junshik Um Seoung soo lee Ji Yi lee Yong Pyo Kim Department of Health Management Kyungin Women’s UniversityIncheon 21041Korea Department of Environmental Science and Engineering Ewha Woman’s UniversitySeoulKorea Department of Environmental Engineering Konkuk UniversitySeoulKorea Korea Polar Research Institute IncheonKorea Department of Environment Hankuk University of Foreign StudiesYonginKorea Department of Atmospheric Sciences Pusan National UniversityBusanKorea Earth System Science Interdisciplinary Center University of MarylandCollege ParkMDUSA Research Center for Climate Sciences Pusan National UniversityBusanKorea Department of Chemical Engineering and Materials Science Ewha Womans UniversitySeoulKorea

The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet scavenging process has been poorly treated,especially during the removal of fine particles.This makes the numerical simulation of below-cloud scavenging in large-scale aerosolmodels unrealistic.To consider the slip effects of submicron particles,a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor.The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles.The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation.Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268,the coefficient of a and b in∧m=aRb spread in the range of 0.0002-0.1959 for a and 0.3261-0.525 for b over a size distribution of GSD of 1.3–2.5 and a geometric mean diameter of 0.01-2.5μm.Overall,this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity.This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity.Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.

关键词： Below-cloud scavenging Polydisperse aerosol Parameterization Cunningham correction factor Scavenging coefficient

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Preface: Nano/Micro Structures in Application of Computational Mechanics

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Computer Modeling in Engineering & Sciences 2019年第8期120卷 235-237页

作者： chang-Chun lee Nien-Ti Tsou Taek-soo Kim Department of Power Mechanical Engineering National Tsing Hua UniversityHsinchu 30013Taiwan Department of Material Science and Engineering National Chiao Tung UniversityHsinchu 30013Taiwan Department of Mechanical Engineering KAISTDaejeon 34141Korea

Many important issues of structures,such as lattice mismatch,compatibility,orientation,evolution,phase transition,surfaces,interfaces,defects,and domain engineering,have attracted considerable interest.The corresponding mechanisms of these issues have not been fully elucidated.Computational mechanics has been widely used to investigate such complexities in nano/microstructures in recent decades.In this special issue,leading experts in their respective fields are invited to present their new insight into the theoretical calculation and modeling of nano/microstructures.Nine articles are collected.A brief introduction on each article is provided below.

关键词： compatibility insight mechanisms

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Microfluidic dual loops reactor for conducting a multistep reaction

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Frontiers of Chemical Science and Engineering 2018年第2期12卷 239-246页

作者： Si Hyung Jin Jae-Hoon Jung Seong-Geun Jeong Jongmin Kim Tae Jung Park chang-soo lee Department of Chemical Engineering Chungnam National University Daejeon 34134 Korea Lotte Chemical R&D Center Daejeon 34110 Korea Department of Chemistry Chung-Ang University Seoul 06974 Korea

Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that enables multistep reaction by integrating two identical loop reactors. Specifically, reactants A and B are synthesized in the first loop reactor and transferred to the second loop reactor to synthesize with reactant C to form the final product. These individual reactions have nano-liter volumes and are carded out in a stepwise manner in each reactor without any cross-contamination issue. To pre- cisely control the mixing efficiency in each loop reactor, we investigate the operating pressure and the operating frequency on the mixing valves for rotary mixing. This microfluidic dual loops reactor is integrated with several valves to realize the fully automated unit operation of a multistep reaction, such as metering the reactants, rotary mixing, transportation, and collecting the product. For proof of concept, CdSeZn nanopartieles are successfully synthesized in a microfluidic dual loops reactor through a fully automated mukistep reaction. Taking all of these features together, this microfluidic dual loops reactor is a general microfluidic screening platform that can synthesize various materials through a multistep reaction.

关键词： microfluidics multistep reaction rotary mixing nanoparticle

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Velocity Profiles between Two Baffles in a Shell and Tube Heat Exchanger

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Journal of Thermal Science 2015年第4期24卷 356-363页

作者： Tae-Hyun chang chang-Hoan lee Hae-soo lee Kwon-soo lee Senior Research Fellow of RESEAT Korea Institute of Science and Technology Information Korea Institute of Science and Technology Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University International University of Korea

Heat exchangers are extensively utilized for waste heat recovery,oil refining,chemical processing,and steam generation.In this study,velocity profiles are measured using a 3D particle image velocimetry(PIV)system between two baffles in a shell and tube heat exchanger for parallel and counter flows.The PIV and computational fluid dynamics results show the occurrence of some strong vectors near the bottom.These vectors are assumed due to the clearance between the inner tubes and the front baffle.Therefore,the major parts of the vectors are moved out through the bottom opening of the rear baffle,and other vectors produce a large circle between the two baffles.Numerical simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent software.The k-εturbulence model is employed to calculate the flows along the heat exchanger.

关键词：管壳式换热器速度分布计算流体动力学 FLUENT软件隔板粒子图像测速管式换热器余热回收

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Microstructure of fast tool servo machining on copper alloy

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中国有色金属学会会刊：英文版 2012年第S3期22卷 820-824页

作者： Hong LU soo-chang CHOI Sang-min lee Deug-woo lee Department of Nano Fusion Technology Pusan National University Korea Institute of Machinery & Materials Department of Nano Mechatronics Engineering Pusan National University

The development of the fast tool servo (FTS) for precision machining was investigated.The micron machining performance of a piezoelectric-assisted FTS on copper alloy was evaluated.The results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the FTS.The excessive driving frequency increases the formation of burrs.The effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.

关键词： fast tool servo microstructure piezoelectric diamond machining copper alloy

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Effects of an Urban Park and Residential Area on the Atmospheric CO_2 Concentration and Flux in Seoul,Korea

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Advances in Atmospheric Sciences 2013年第2期30卷 503-514页

作者： Moon-soo PARK Seung Jin JOO chang Seok lee Center for Atmospheric and Environmental Modeling Seoul 151 919Korea Life and Environmental Engineering Seoul Women's UniversitySeoul 139 774Korea

The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.

关键词： C02 concentration C02 flux Seoul urban forest urban residential region

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Corrugated surface microparticles with chitosan and levofloxacin for improved aerodynamic performance

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Asian Journal of Pharmaceutical Sciences 2023年第3期18卷 146-158页

作者： chang-soo Han Ji-Hyun Kang Eun hye Park Hyo-Jung lee So-Jeong Jeong Dong-Wook Kim Chun-Woong Park College of Pharmacy Chungbuk National UniversityCheongju 28160Republic of Korea School of Pharmacy Jeonbuk National UniversityJeonju 54896Republic of Korea College of Pharmacy Wonkwang UniversityIksan 54538Republic of Korea

Corrugated surface microparticles comprising levofloxacin(LEV),chitosan and organic acid were prepared using the 3-combo spray drying method.The amount and the boiling point of the organic acid affected the degree of roughness.In this study,we tried to improve the aerodynamic performance and increase aerosolization by corrugated surface microparticle for lung drug delivery efficiency as dry powder inhaler.HMP175 L20 prepared with 175 mmol propionic acid solution was corrugated more than HMF175 L20 prepared with 175 mmol formic acid solution.The ACI and PIV results showed a significant increase in aerodynamic performance of corrugated microparticles.The FPF value of HMP175 L20 was 41.3%±3.9%compared with 25.6%±7.7%of HMF175 L20.Corrugated microparticles also showed better aerosolization,decreased x-axial velocity,and variable angle.Rapid dissolution of drug formulationswas observed in vivo.Lowdoses administered to the lungs achieved higher LEV concentrations in the lung fluid than high doses administered orally.Surface modification in the polymer-based formulation was achieved by controlling the evaporation rate and improving the inhalation efficiency of DPIs.

关键词： Chitosan Organic acid Levofloxacin Corrugated surface Aerodynamic performance

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“One stone,two birds”solvent system to fabricate microcrystalline cellulose–Ti_(3)C_(2)T_(x)nanocomposite film as a flexible dielectric and thermally conductive material

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Nano Research 2023年第2期16卷 3240-3253页

作者： Yong-Zhu Yan Shuwei Li Sung soo Park Wei-Jin Zhang Jun Seok lee Jung Rae Kim Dong Gi Seong chang-Sik Ha Department of Polymer Science and Engineering School of Chemical EngineeringPusan National UniversityBusan 46241Republic of Korea School of Chemical and Biomolecular Engineering Pusan National UniversityBusan 46241Republic of Korea Division of Advanced Materials Engineering Dong-Eui UniversityBusan 47340Republic of Korea

A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was developed.The MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control drying.The MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial polarization.Thus,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered structure.Additionally,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and flexibility.Furthermore,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of MXene.Moreover,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous systems.With the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.

关键词： Ti_(3)C_(2)T_(x) microcrystalline cellulose flexible dielectric thermally conductive N,N-dimethylacetamide/lithium chloride(DMAc/LiCl) compatibility

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Cytotoxicity and anti-inflammatory effects of root bark extracts of Acanthopanax henryi

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Chinese Journal of Natural Medicines 2014年第2期12卷 121-125页

作者： KIM Jong-Hwan LIU Xiang-Qian DAI Ling YOOK chang-soo lee Kyung-Tae Herbal Medicine Research Division Korea Food & Drug Administration Hunan Key Laboratory of Traditional Chinese Medicine modernization School of Pharmacy Hunan University of Chinese Medicine College of Pharmacy Kyung-Hee University

AIM: To investigate the cytotoxicity, anti-inflammatory activity, and action mechanism of root bark extracts of Acanthopanax henryi. METHOD: The hot methanol extract of the root bark of A. henryi was subjected to XAD-4 column chromatography eluting with a gradient of methanol in water. The cytotoxicity and anti-inflammatory effects of the MeOH fractions were evaluated on the inhibition on lipopolysaccharide(LPS)-induced nitric oxide, prostaglandin E2, interleukin-1β, and interleukin-6 production in RAW 264.7 macrophages. RESULTS: The 80% MeOH fraction was a better inhibitor of LPS-induced NO, PGE2, IL-1β, and IL-6 production, and expression of inducible nitric oxide synthase(iNOS) at the protein levels in a concentration-dependent manner. CONCLUSION: The 80% MeOH fraction of A. henryi root bark has significant anti-inflammatory activity. This provides a pharmacological basis for clinical application for the treatment of inflammation.

关键词： Acanthopanax henryi(Oliv.) Harms Root bark extract Cytotoxic activity Anti-inflammatory activity

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