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Nano-Micro Letters 2024年第10期16卷 618-637页

作者： Se In kim Woong-Ju kim Jin Gu Kang dong-Wan kim School of Civil Environmental and Architectural EngineeringKorea University02841 SeoulSouth Korea Nanophotonics Research Center Korea Institute of Science and Technology02792 SeoulSouth Korea

Doped two-dimensional(2D)materials hold significant promise for advancing many technologies,such as microelectronics,optoelectronics,and energy ***,n-type 2D oxidized Si nanosheets,namely n-type siloxene(n-SX),are employed as Li-ion battery *** thermal evaporation of sodium hypophosphite at 275℃,P atoms are effectively incorporated into siloxene(SX)without compromising its 2D layered morphology and unique Kautsky-type crystal ***,selective nucleophilic substitution occurs,with only Si atoms being replaced by P atoms in the O_(3)≡Si-H *** resulting n-SX possesses two delocalized electrons arising from the presence of two electron donor types:(i)P atoms residing in Si sites and(ii)H *** doping concentrations are varied by controlling the amount of precursors or their mean free *** at 2000 mA g^(-1),the n-SX electrode with the optimized doping concentration(6.7×10^(19) atoms cm^(-3))delivers a capacity of 594 mAh g^(-1) with a 73%capacity retention after 500 *** improvements originate from the enhanced kinetics of charge transport processes,including electronic conduction,charge transfer,and solid-state *** approach proposed herein offers an unprecedented route for engineering SX anodes to boost Li-ion storage.

关键词： Li-ion battery Two-dimensional N-type siloxene Doping mechanism Kinetics

Thresholdless coherence in a superradiant laser

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Light(Science & Applications) 2024年第11期13卷 2549-2555页

作者： Seung-Hoon Oh Jinuk kim Junseo ha Gibeom Son Kyungwon An Department of Physics and Astronomy&Institute of Applied Physics Seoul National UniversitySeoulKorea Korea Research Institute of Standards and Science DaejeonKorea

Lasing threshold in the conventional lasers is the minimum input power required to initiate laser *** has been widely accepted that the conventional laser threshold occurring around a unity intracavity photon number can be eliminated in the input-output curve by making the so-calledβparameter approach *** recent experiments,however,have revealed that even in this case the photon statistics still undergo a transition from coherent to thermal statistics when the intracavity mean photon number is decreased below *** the coherent output is only available above the diminished threshold,the long-sought promise of thresholdless lasers to produce always coherent light has become ***,we present an always-coherent thresholdless laser based on superradiance by two-level atoms in a quantum superposition state with the same phase traversing a high-Q *** lasing was observed without the conventional lasing threshold around the unity photon number and the photon statistics remained near coherent even below *** coherence was improved by reducing the coupling constant as well as the excited-state amplitude in the superposition *** results pave a way toward always-coherent thresholdless lasers with more practical media such as quantum dots,nitrogen-vacancy centers and doped ions in crystals.

关键词： laser coherent lasing

Additive manufacturing of flexible 3D surface electrodes for electrostatic adhesion control and smart robotic gripping

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Friction 2023年第11期11卷 1974-1986页

作者： dong Geun kim Hyeongmin JE AJohn haRT Sanha kim Department of Mechanical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA

Mechanically flexible surface structures with embedded conductive electrodes are attractive in contact-based devices,such as those used in reversible dry/adhesion and tactile *** shapes of the surface structures strongly determine the contact behavior and therefore the resulting adhesion and sensing functionalities;however,available features are often restricted by fabrication ***,we additively manufacture elastomeric structure arrays with diverse angles,shapes,and sizes;this is followed by integration of conductive nanowire *** fabricated flexible three-dimensional(3D)surface electrodes are mechanically compliant and electrically conductive,providing multifunctional ability to sense touch and to switch adhesion via a combined effect of shear-and electro *** designed soft,anisotropic flexible structures to mimic the gecko’s reversible adhesion,which is governed by van der Waals forces;we integrated nanowires to further manipulate the localized electric field among the adjacent flexible 3D surface electrodes to provide additional means to digitally tune the electrostatic attraction at the contact *** addition,the composite surface can sense the contact force via capacitive *** our flexible 3D surface electrodes,we demonstrate a complete soft gripper that can grasp diverse convex objects,including metal,ceramic,and plastic products,as well as fresh fruits,and that exhibits 72%greater electroadhesive gripping force when voltage is applied.

关键词： electroadhesion tactile sensing robotic gripper additive manufacturing dry adhesive

Solid-state phase transformations toward a metal-organic framework of 7-connected Zn_(4)0 secondary building units

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Nano Research 2021年第2期14卷 411-416页

作者： Jaehui kim Junsu ha Jae Hwa Lee Hoi Ri Moon Department of Chemistry Ulsan National Institute of Science and Technology(UNIST) Ulsan 44919Republic of Korea

In the development of metal-organic frameworks(MOFs),secondary building units(SBUs)have been utilized as molecular modules for the construction of nanoporous materials with robust *** solvothermal synthetic conditions,dynamic changes in the metal coordination environments and ligand coordination modes of SBUs determine the resultant product ***,MOF phases with new topologies can also be achieved by post-synthetic treatment of as-synthesized MOFs via the introduction of acidic or basic moieties that cause the simultaneous cleavage/reformation of coordination bonds in the solid *** this sense,we studied the solid-state transformation of two ndc-based Zn-MOFs(ndc=1,4-naphthalene dicarboxylate)with different SBUs but the same pcu topology to another MOF with sev *** of the chosen MOFs with pcu nets is[Zn_(2)(ndc)_(2)(bpy)]_(n)(bpy=4,4,-bipyridine),(6C_(bpy)-MOF)consisting of a 6-connected pillared-paddlewheel SBU,and the other is IRMOF-7 composed of 6-connected Zn40(C 00)6 SBUs and *** post-structural modification,these pcu MOFs were converted into the same MOF with sev topology constructed from the uncommon 7-connected Zri_(4)O(COO)_(7)SBU(7C-MOF).The appropriate post-synthetic conditions for the transformation of each SBUs were systematically *** addition,the effect of the pillar molecules in the pillared-paddlewheel MOFs on the topology conversion was studied in terms of the linker basicity,which determines the inertness during the solid-state phase *** post-synthetic modification approach is expected to expand the available methods for designing and synthesizing MOFs with controlled topologies.

关键词： metal-organic framework secondary building units solid-state transform ation linker basicity ligand addition reaction

Dynamic soil-structure interaction analysis in time domain based on a modified version of perfectly matched discrete layers

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第1期12卷 168-179页

作者： dong Van Nguyen Dookie kim Department of Civil Engineering Kunsan National University558 Daehak-roGunsan-si54150Republic of Korea

Analysis of soil-structure interaction is commonly conducted by dividing the infinite domain of the soil into two domains:interior and exterior *** interior domain is bounded in a small region,while the exterior domain is replaced by artificial boundary *** choice of artificial boundary conditions is a critical issue in the analysis of soil-structure interaction *** matched discrete layer(PMDL)has been proved as a good approach for modeling the exterior *** this study,a modified version of the PMDLs,*** with analytical wavelengths(AW-PMDLs),is used in the soil-structure interaction analysis in time domain,which essentially can be regarded as an extension of the analysis in frequency domain,being previously proven to be *** verifications are *** results demonstrate that the proposed method performs well in the analysis of soilstructure interaction problems in time domain.

关键词： Soil-structure interaction Time domain Wave propagation Wavelength Infinite domain Perfectly matched discrete layer(PMDL)

Combined treatment of phacoemulsification and single-port limited pars plana vitrectomy in acute angle-closure glaucoma

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International Journal of Ophthalmology(English edition) 2019年第6期12卷 974-979页

作者： ha Jeong Noh Seong Taeck kim Department of Ophthalmology Chosun University Hospital

AIM: To evaluate the efficacy of combined treatment of phacoemulsification(PE) and micro-incisional single-port transconjunctival limited pars plana vitrectomy(PPV) in acute angle-closure glaucoma(AACG).METHODS: A retrospective study included 26 patients who underwent PE diagnosed with AACG. Among them, 16 patients(16 eyes) underwent PE alone, 10 patients(10 eyes) underwent combined limited vitrectomy and PE. Then we compared intraocular pressure(IOP), anterior chamber angle, anterior chamber depth, central corneal thickness and corneal endothelial cell count before and after surgery, and effective PE time during cataract ***: Effective PE time was shorter in the combined surgery group than in the single surgery group(P=0.040). There was no statistically significant difference in IOP and best-corrected visual acuity between the two groups postoperatively. At 6 mo postoperatively, there was no difference in the anterior chamber angle, anterior chamber depth, and central corneal thickness between two groups, but corneal endothelial cell count was higher in the combined surgery group than in the single surgery group(P=0.046). No complication such as vitreoretinal disease, endophthalmitis, bullous keratopathy was ***: Combined micro-incisional single-port transconjunctival limited PPV and PE are more effective and safer than PE alone because of less operation time and fewer complications for management of AACG.

关键词： limited vitrectomy phacoemulsification acute angle-closure glaucoma

Anti-inflammatory and Antimicrobial Effects of Anthocyanin Extracted from Black Soybean on Chronic Bacterial Prostatitis Rat Model

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Chinese Journal of Integrative Medicine 2018年第8期24卷 621-626页

作者： Byung Il Yoon Woong Jin Bae Yong Sun Choi Su Jin kim U Syn ha Sung-Hoo Hong dong Wan Sohn Sae Woong kim Department of Urology International St Mary's HospitalThe Catholic Kwandong University of Korea Department of Urology College of MedicineThe Catholic University of Korea

Objective： To investigated the anti-inflammatory and antimicrobial effects of anthocyanins extracted from black soybean on the chronic bacterial prostatitis（CBP） rat ***： The SpragueDawley rats were divided into 4 groups,including control,ciprofloxacin,anthocyanins and anthocyanins with ciprofloxacin groups（n=8 in each group）.Then,drip infusion of bacterial suspension（Escherichia coli Z17O2：K1：H^-） into Sprague-Dawley rats was conducted to induce *** 4 weeks,results of prostate tissue,urine culture,and histological analysis on the prostate were analyzed for each ***： The use of ciprofloxacin,anthocyanins,and anthocyanins with ciprofloxacin showed statistically significant decreases in bacterial growth and improvements in the reduction of prostatic inflammation compared with the control group（P〈0.05）.The anthocyanins with ciprofloxacin group showed a statistically significant decrease in bacterial growth and improvement in prostatic inflammation compared with the ciprofloxacin group（P〈0.05）.Conclusions： These results suggest that anthocyanins may have anti-inflammatory and antimicrobial effects,as well as a synergistic effect with ***,we suggest that the combination of anthocyanins and ciprofloxacin may be effective in treating CBP to obtain a higher rate of treatment success.

关键词： prostatitis anti-bacterial agents anthocyanins

“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 *** 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 *** MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial ***,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 ***,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 ***,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of ***,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 *** 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

Study on the Wiping Gas Jet in Continuous Galvanizing Line

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Journal of Thermal Science 2011年第3期20卷 242-247页

作者： Yong-Hun Kweon Heuy-dong kim POSCO Technical Research Laboratories 699 Gumho-dong GwangyangJeonnam 545-090 Korea School of Mechanical Engineering Andong National UniversityAndong 760-749 Korea

In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.

关键词： Gas-Jet Wiping Hot-Dip Galvanizing Impact Pressure Coating Thickness

Shear deformable finite beam elements for composite box beams

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Acta Mechanica Sinica 2014年第2期30卷 223-240页

作者： Nam-Il kim dong-Ho Choi Department of Architectural Engineering Sejong University Department of Civil and Environmental Engineering Hanyang University

The shear deformable thin-walled composite beams with closed cross-sections have been developed for coupled flexural, torsional, and buckling analyses. A theoretical model applicable to the thin-walled laminated composite box beams is presented by taking into account all the structural couplings coming from the material anisotropy and the shear deformation effects. The current composite beam includes the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. Seven governing equations are derived for the coupled axial-flexural-torsional-shearing buckling based on the principle of minimum total potential energy. Based on the present analytical model, three different types of finite composite beam elements, namely, linear, quadratic and cubic elements are developed to analyze the flexural, torsional, and buckling problems. In order to demonstrate the accuracy and superiority of the beam theory and the finite beam elements developed by this study,numerical solutions are presented and compared with the results obtained by other researchers and the detailed threedimensional analysis results using the shell elements of ABAQUS. Especially, the influences of the modulus ratio and the simplified assumptions in stress-strain relations on the deflection, twisting angle, and critical buckling loads of composite box beams are investigated.

关键词： Thin-walled Composite box beam Deflection Twisting angle Buckling load Shear deformation