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Nitrogen-and Oxygen-Containing Porous Ultrafine Carbon Nanofiber:A Highly Flexible Electrode Material for Supercapacitor

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Journal of Materials Science & Technology 2017年第5期33卷 424-431页

作者： Kai Wei Kyu-Oh Kim Kyung-hun Song Chang-Yong kang jung soon Lee Mayakrishnan Gopiraman Ick-Soo Kim College of Textile and Clothing Engineering Soochow UniversitySuzhou215021China Nano Fusion Technology Research Group Division of Frontier FibersInstitute for Fiber Engineering(IFES)Interdisciplinary Cluster for Cutting Edge Research(ICCER)Shinshu UniversityTokida 3-15-1UedaNagano Prefecture386-8567Japan Department of Fiber System Engineering Dankook UniversityYoungin 448-701Republic of Korea Department of Clothing&Textiles PaiChai UniversityDaejeon 302-735Republic of Korea Department of Metallurgical Engineering Pukyong National UniversityBusan 608-739Republic of Korea Department of Clothing and Textiles Chungnam National UniversityDaejeon 305-764Republic of Korea

Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late）（PMMA）] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios （10/0, 7：3, 5：5 and 3：7） were chosen and found that the PAN/PMMA ratio of 3：7 （PAN/PMMA-3：7） is the optimum one. BET anal- ysis showed the specific surface area of the u-CNFs-3：7 was 46Z57 m2/g with an excellent pore volume （1.15 cms g-l） and an average pore size （9.48 nm）： it is about 25 times higher than the conventional CNFs （c-CNFs）. TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber di- ameter of-50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods, the u-CNFs-3：7 was used without any activation, chemical or mechanical modifications. The u-CNFs- 3：7 showed a better specific capacitance of 86 Fig in 1 mol/L 1-12S04 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3：7 an alternative choice to the existing CNFs for the supercapacitors.

关键词： Carbon fiber Porosity Electron microscopy Surface analysis Supercapacitor

An improvement of snow/cloud discrimination from machine learning using geostationary satellite data

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International Journal of Digital Earth 2022年第1期15卷 2355-2375页

作者： Donghyun Jin Kyeong-Sang Lee Sungwon Choi Noh-hun Seong Daeseong jung Suyoung Sim Jongho Woo Uujin Jeon Yugyeong Byeon Kyung-Soo Han Division of Earth Environmental System Science (Major of Spatial Information System Engineering) Pukyong National UniversityBusanKorea Korea Institute of Ocean Science and Technology Korea Ocean Satellite CenterBusanKorea BK21 FOUR Project of the School of Integrated Science for Sustainable Earth Environmental Disaster Pukyong National UniversityBusanKorea

Snow and cloud discrimination is a main factor contributing to errors in satellite-based snow *** address the error,satellite-based snow cover performs snow reclassification tests on the cloud pixels of the cloud mask,but the error still *** Learning(ML)has recently been applied to remote sensing to calculate satellite-based meteorological data,and its utility has been *** this study,snow and cloud discrimination errors were analyzed for GK-2A/AMI snow cover,and ML models(Random Forest and Deep Neural Network)were applied to accurately distinguish snow and *** ML-based snow reclassified was integrated with the GK-2A/AMI snow cover through *** used the S-NPP/VIIRS snow cover and ASOS in situ snow observation data,which are satellite-based snow cover and ground truth data,as validation data to evaluate whether the snow/cloud discrimination is *** ML-based integrated snow cover detected 33–53%more snow compared to the GK-2A/AMI snow *** terms of performance,the F1-score and overall accuracy of the GK-2A/AMI snow cover was 73.06%and 89.99%,respectively,and those of the integrated snow cover were 76.78–78.28%and 90.93–91.26%,respectively.

关键词： Geostationary satellite GK-2A/AMI snow cover product snow/cloud discrimination machine learning remote sensing

Exploring the experimental study and density functional theory calculations of symmetric and asymmetric chalcogen atoms interacted molybdenum dichalcogenides for lithium-ion batteries

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Journal of Materials Science & Technology 2023年第31期162卷 44-56页

作者： Dhanasekaran Vikraman Sajjad Hussain Zeesham Abbas K.Karuppasamy Woo-Seok kang P.Santhoshkumar A.Kathalingam Jongwan jung Hyun-Seok Kim Division of Electronics and Electrical Engineering Dongguk University-SeoulSeoul 04620Republic of Korea Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Hybrid Materials Center(HMC) Sejong UniversitySeoul 05006Republic of Korea Millimeter-wave Innovation Technology(MINT)Research Center Dongguk University-SeoulSeoul 04620Republic of Korea

Two-dimensional asymmetric chalcogen atoms attached to Janus nanoparticles have fascinated research attention owing to their distinctive properties and characteristics for various *** paper proposed a facile synthesis to produce efficient molybdenum-based symmetric and asymmetric chalcogens bounded by X Mo X and TeMo X ***,the fabricated X Mo X and TeMo X nanostruc-tures were employed as anodes for lithiumion batteries(LIBs).Assembled LIBs using TeMoS and TeMoSe Janus anodes achieved 2610 and 2073 mAh g^(-1)reversible capacity at 0.1 A g^(-1),respectively for the halfcell configuration,which is outstanding performance compared with previous *** rate capability performances at 0.1-20 A g^(-1)and exceptional cycling solidity confirmed high charge and discharge capacities for TeMo X Janus lithium-ion battery *** addition,the full cell device with TeMoS//LiCoO_(2)configuration explored the discharge capacity of 1605 mAh g^(-1)at 0.1 A g^(-1)which suggests their excellent electrochemical *** density functional theory approximations established the significance of assembled symmetric and asymmetric chalcogen atoms interacted with X Mo X and TeMo X anode materials for ***,the present investigation supports a new approach to creating two-dimensional materials based on asymmetric chalcogen atoms with core metal to effectively increase desirable energy storage characteristics.

关键词： TeMoS TeMoSe Janus Li-ion battery

IMAGE RESTOR ATION UNDER CAUCHY NOISE WITH SPA RSE REPR ESENTATION PRIOR AND TOTAL GENER ALIZED VA RIATION

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Journal of Computational Mathematics 2021年第1期39卷 81-107页

作者： Miyoun jung Myungjoo kang Department of Mathematics Hankuk University of Foreign StudiesYonginKorea Department of Mathematical Sciences Seoul National UniversitySeoulKorea

This article introduces a novel variational model for restoring images degraded by Cauchy noise and/or *** model integrates a nonconvex data-fidelity term with two regularization terms,a sparse representation prior over dictionary learning and total generalized variation(TGV)*** sparse representation prior exploiting patch information enables the preservation of fine features and textural patterns,while adequately denoising in homogeneous regions and contributing natural visual *** regularization further assists in effectively denoising in smooth regions while retaining *** adopting the penalty method and an alternating minimization approach,we present an efficient iterative algorithm to solve the proposed *** results establish the superiority of the proposed model over other existing models in regard to visual quality and certain image quality assessments.

关键词： Image restoration Cauchy noise Sparse representation prior Dictionary learn-ing Total generalized variation.

Water stable and matrix addressable OLED fiber textiles for wearable displays with large emission area

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npj Flexible Electronics 2022年第1期6卷 664-671页

作者： Hayoung Song Young Jin Song Jinwook Hong Ki Suk kang Sera Yu Ha-Eun Cho Jae-hun Kim Sung-Min Lee School of Materials Science and Engineering Kookmin UniversitySeoul 02707Republic of Korea School of Electrical Engineering KAISTDaejeon 34141Republic of Korea

Organic light-emitting diode(OLED)fibers with favorable electroluminescence properties and interconnectable pixel configurations have represented the potential for wearable electronic textile ***,the current technology of OLED fiber-based textile displays still leaves to be desired due to several challenges,including limited emission area and lack of encapsulation *** we present a fibrous OLED textile display that can attain a large emission area and long-term stability by implementing addressable networks comprised of integrated phosphorescence OLED fibers and by designing multilayer *** integrated fiber configuration offers decoupled functional fiber surfaces for an interconnectable 1-dimensional OLED pixel array and a data-addressing *** triadic metal/ultrathin oxide/polymer multilayer enables not only the oxygen/water permeation inhibition but also the controllable conductive channels of dielectric *** with reliable bending stability,the long-term operation of OLED textiles in water manifests the feasibility of the present device concept toward water-resistant full-emitting-area fibrous textile displays.

关键词： fiber OLED wear

Is anoplasty superior to scar revision surgery for posthemorrhoidectomy anal stenosis?Six years of experience

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World Journal of Clinical Cases 2022年第22期10卷 7698-7707页

作者： Yu-Tse Weng Kuan-jung Chu Kuan-Hsun Lin Chun-Kai Chang jung-Cheng kang Chao-Yang Chen Je-Ming Hu Ta-Wei Pu Division of Plastic and Reconstructive Surgery Department of SurgeryTri-Service General HospitalNational Defense Medical CenterTaipei 114Taiwan National Defense Medical Center Taipei 114Taiwan Division of Thoracic Surgery Department of SurgeryTri-Service General HospitalNational Defense Medical CenterTaipei 114Taiwan Division of Plastic and Reconstructive Surgery Department of SurgeryZuoying BranchKaohsiung Armed Forces General HospitalKaohsiung 813Taiwan Division of Colon and Rectal Surgery Department of SurgeryTaiwan Adventist HospitalTaipei 105Taiwan Division of Colon and Rectal Surgery Department of SurgeryTri-Service General HospitalNational Defense Medical CenterTaipei 114Taiwan Division of Colon and Rectal Surgery Department of SurgerySongshan branchTri-Service General HospitalNational Defense Medical CenterTaipei 105Taiwan

BACKGROUND Anal stenosis is a rare but frustrating condition that usually occurs as a complication of *** severity of anal stenosis can be classified into three categories:mild,moderate,and *** are two main surgical treatments for this condition:scar revision surgery and anoplasty;however,no studies have compared these two approaches,and it remains unclear which is preferrable for stenoses of different *** To compare the outcomes of scar revision surgery and double diamond-shaped flap *** Patients with mild,moderate,or severe anal stenosis following hemorrhoidectomy procedures who were treated with either scar revision surgery or double diamond-shaped flap anoplasty at our institution between January 2010 and December 2015 were investigated and *** severity of stenosis was determined via anal examination performed digitally or using a Hill-Ferguson *** explored patient characteristics included age,sex,preoperative severity of anal stenosis,preoperative symptoms,and preoperative adjuvant therapy;moreover,their postoperative quality of life was measured using a 10-point *** underwent proctologic follow-up examinations one,two,and four weeks after *** We analyzed 60 consecutive patients,including 36 men(60%)and 24 women(40%).The mean operative time for scar revision surgery was significantly shorter than that for double diamondshaped flap anoplasty(10.14±2.31[range:7-15]min vs 21.62±4.68[range:15-31]min;P<0.001).The average of length of hospital stay was also significantly shorter after scar revision surgery than after anoplasty(2.1±0.3 vs 2.9±0.4 d;P<0.001).Postoperative satisfaction was categorized into four groups:45 patients(75%)reported excellent satisfaction(scores of 8-10),13(21.7%)reported good satisfaction(scores of 6-7),two(3.3%)had no change in satisfaction(scores of 3-5),and none(0%)had scores indicating poor satisfaction(1-2).As such,most patients were satisfied wi

关键词： Anal canal Anoplasty Scar revision Stenosis Surgery-induced tissue adhesions Surgical flaps

Densification simulation of compacted Al powders using multi-particle finite element method

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中国有色金属学会会刊：英文版 2009年第B9期19卷 68-75页

作者： Kyung-hun LEE jung-Min LEE Byung-Min KIM School of Mechanical Engineering Pu san National University

The powder compaction simulations were performed to demonstrate deformation behavior of particles and estimate the effect of different punch speeds and particle diameters on the relative density of powder by a multi-particle finite element model(MPFEM). Individual particle discretized with a finite element mesh allows for a full description of the contact mechanics. In order to verify the reliability of compaction simulation by MPFEM, the compaction tests of porous aluminum with average particle size of 20 μm and 3 μm were performed at different ram speeds of 5, 15, 30 and 60 mm/min by MTS servo-hydraulic tester. The results show that the slow ram speed is of great advantage for powder densification in low compaction force due to sufficient particle rearrangement and compaction force increases with decrease in average particle size of aluminum.

关键词：粉末压实粉末粒子多孔铝有限元法模拟致密化平均粒径有限元模型

Yolk-shell-structured （***.s）9S8 solid-solution powders：Synthesis and application as anode materials for Na-ionbatteries

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Nano Research 2017年第9期10卷 3178-3188页

作者： jung Hyun Kim Yun Chan kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea

Multicomponent metal sulfide materials with a yolk–shell structure and a single phase were studied for the first time as anode materials for sodium-ion batteries. Yolk–shell-structured Fe–Ni–O powders with a molar ratio of iron and nickel components of 1/1 were prepared via one-pot spray pyrolysis. The prepared Fe–Ni–O powders were transformed into yolk–shell-structured (Fe0.5Ni0.5)9S8 solid-solution powders via a sulfidation process. The initial discharge and charge capacities of the (Fe0.5Ni0.5)9S8 powders at a current density of 1 A·g−1 were 601 and 504 mA·h·g−1, respectively. The discharge capacities of the (Fe0.5Ni0.5)9S8 powders for the 2nd and 100th cycle were 530 and 527 mA·h·g−1, respectively, and their corresponding capacity retention measured from the 2nd cycle was 99%. The (Fe0.5Ni0.5)9S8 powders had high initial discharge and charge capacities at a low current density of 0.1 A·g−1, and the reversible discharge capacity decreased slightly from 568 to 465 mA·h·g−1 as the current density increased from 0.1 to 5.0 A·g−1. The synergetic effect of the novel yolk–shell structure and the multicomponent sulfide composition of the (Fe0.5Ni0.5)9S8 powders resulted in excellent sodium-ion storage performance.

关键词： metal sulfide multicomponent sulfide yolk–shell sodium-ion batteries spray pyrolysis

Controlling a lithium surface with an alkyl halide nucleophile exchange

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Journal of Energy Chemistry 2021年第11期30卷 617-626,I0015页

作者： jung-hun Lee Thuy Hoai Linh Vuong Soo Min Hwang Jae-hun Kim Young-Jun Kim SKKU Advanced Institute of Nanotechnology(SAINT) Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Nano Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea School of Materials Science and Engineering Kookmin UniversitySeoul 02707Republic of Korea

Despite its high theoretical energy density, lithium metal faces huge challenges in its implementation as an anode for Li secondary batteries because of its uncontrollable dendritic growth and large volume change during plating/stripping processes. These geometric changes cause degradation in a cell’s cycle life and performance and can lead to short-circuits and explosions. Here, we report a new approach to producing a LiF-rich phase on the lithium anode surface by employing a “bi-phase” separator. We fabricated it by coating polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) onto a cellulose separator. The coverage of coating was adjusted by varying its concentration in the coating solution. The combination of cellulose and PVDF-HFP produced a LiF-rich solid-electrolyte interphase layer on the Li metal surface via an alkyl halide nucleophile exchange in contact with the bi-phase separator during plating. Symmetric cell tests show that the bi-phase separator extends the cycle life by more than 300 h, with overpotentials of less than 100 mV under plating/stripping at 2 mA cm^(−2) for a capacity of 2 mAh cm^(−2). The formation mechanism of the LiF-rich phase is suggested from spectroscopic analyses.

关键词： Li metal anode PVDF-HFP Cellulose LiF Phase inversion