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A novel electrospinning method for self-assembled tree-like fibrous scaffolds:Microenvironment-associated regulation of MSC behavior and bone regeneration

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Journal of Materials Science & Technology 2022年第20期115卷 52-70页

作者： jeong in kim Ju Yeon kim Sung-Ho Kook jeong-Chae Lee Cluster for Craniofacial Development and Regeneration Research Institute of Oral Biosciences and School of DentistryJeonbuk National UniversityJeonju 54896Republic of Korea Department of Bionanosystem Engineering Jeonbuk National UniversityJeonju 54896Republic of Korea Department of Bioactive Material Sciences Research Center of Bioactive MaterialsJeonbuk National UniversityJeonju 54896Republic of Korea

Numerous studies highlight advantages of electrospun scaffolds in bone tissue engineering,in which cellular behavior is tightly affected by fiber topographical cues of ***,the classic electrospinning setup limits a desired presentation of biomimetic fibrous microenvironments that sense mechanosignaling and regulate stem cell *** aims of this study were to fabricate advanced asspun scaffolds presenting tree-like microfiber/nanonet networks and to evaluate their regulatory potentials on behavior of human mesenchymal stem cells(h MSCs)and bone *** we developed a novel electrospinning setup that allowed the presentation of patterned Trunk microfibers(TMF)and/or branched nanonet fibers(BNn Fs)in biomimetic fibrous *** the cellular mechanisms,anisotropichierarchical topography of TMF controlled behavior of h MSCs through focal adhesion formation and Yesassociated protein(YAP)induction,whereas BNn F disturbed such mechanosensing responses in the *** fiber microenvironment-related expression and nuclear localization of YAP *** correlated with the potentials of as-spun scaffolds to enhance osteogenic differentiation of the h MSCs and alveolar bone defect healing in an animal ***,this study provides an advanced approach of the modified electrospinning setup for presentation of biomimetic fibrillar microenvironments in as-spun scaffolds along with their application in stem cell behavior regulation and regenerative tissue engineering.

关键词： Electrospinning Advanced biomimetic scaffolds Stem cell behavior Mechanosensing Bone tissue engineering

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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

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Two-dimensional Dirac plasmon-polaritons in graphene,3D topological insulator and hybrid systems

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Light(Science & Applications) 2022年第11期11卷 2602-2616页

作者： Chihun In Un jeong kim Hyunyong Choi Department of Physics Freie Universitat BerlinBerlin 14195Germany Department of Physical Chemistry Fritz-Haber-lInstitute of the Max-Planck-SocietyBerlin 14195Germany Department of Physics and Astronomy Seoul National UniversitySeoul 08826Republic of Korea Institute of Applied Physics Seoul National UniversitySeoul 08826Republic of Korea Advanced Sensor Laboratory Samsung Advanced Institute of TechnologySuwonGyeonggido 16419Republic of Korea

Collective oscillations of massless particles in two-dimensional(2D)Dirac materials offer an innovative route toward implementing atomically thin devices based on low-energy quasiparticle *** confinement of nearfield distribution on the 2D surface is essential to demonstrate extraordinary optoelectronic functions,providing means to shape the spectral response at the mid-infrared(IR)*** the dynamic polarization from the linear response theory has successfully accounted for a range of experimental observations,a unified perspective was stll elusive,connecting the state-of-the-art developments based on the 2D Dirac ***,we review recent works on graphene and three-dimensional(3D)topological insulator(TI)plasmon-polariton,where the mid-IR and terahertz(THz)radiation experiences prominent confinement into a deep-subwavelength scale in a novel optoelectronic *** presenting general light-matter interactions between 2D Dirac plasmon and subwavelength quasiparticle excitations,we introduce various experimental techniques to couple the plasmonpolaritons with electromagnetic *** and optical controls over the plasmonic excitations reveal the hybridized plasmon modes in graphene and 3D Tl,demonstrating an intense near-field interaction of 2D Dirac plasmon within the highly-compressed *** findings can further be applied to invent optoelectronic biomolecular sensors,atomically thin photodetectors,and laser-driven light sources.

关键词： structure Dirac topological

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Effects of foundation damage and water-level change on vibration modal parameters of gravity-type caisson structure

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Science China(Technological Sciences) 2015年第2期58卷 316-329页

作者： LEE So-Young kim jeong-Tae Department of Ocean Engineering Pukyong National University

In this paper,the effects of foundation damage and water-level change on vibration characteristics of gravity-type caisson structure are examined by analyzing modal parameters extracted from output-only *** achieve the objective,the following approaches are ***,vibration response analysis methods are selected to estimate power spectral density and modal parameters such as natural frequency,damping ratio and mode shape of a lab-scale caisson structural ***,vibration tests on the lab-scale caisson system are performed under a series of test scenarios which include three water-level changes and three damage ***,experimental modal parameters corresponding to the damaging cases as well as the water level cases are extracted by frequency domain decomposition method and stochastic subspace identification ***,the effects of the water-level variation and foundation damage on the extracted modal parameters are examined to assess the feasibility of the vibration-based damage detection in gravity-type caisson structures under water-level uncertainty.

关键词： caisson structure gravity-type structure modal parameter effect of water-level foundation damage

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A Deep Learning Hierarchical Ensemble for Remote Sensing Image Classification

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Computers, Materials & Continua 2022年第8期72卷 2649-2663页

作者： Seung-Yeon Hwang jeong-Joon kim Department of Computer Engineering Anyang UniversityAnyang-si14028Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14028Korea

Artificial intelligence,which has recently emerged with the rapid development of information technology,is drawing attention as a tool for solving various problems demanded by society and *** particular,convolutional neural networks(CNNs),a type of deep learning technology,are highlighted in computer vision fields,such as image classification and recognition and object *** these CNN models requires a large amount of data,and a lack of data can lead to performance degradation problems due to *** CNN architecture development and optimization studies become active,ensemble techniques have emerged to perform image classification by combining features extracted from multiple CNN *** this study,data augmentation and contour image extraction were performed to overcome the data shortage *** addition,we propose a hierarchical ensemble technique to achieve high image classification accuracy,even if trained from a small amount of ***,we trained the UCMerced land use dataset and the contour images for each image on pretrained VGGNet,GoogLeNet,ResNet,DenseNet,and *** then apply a hierarchical ensemble technique to the number of cases in which each model can be *** experiments were performed in cases where the proportion of training datasets was 30%,50%,and 70%,resulting in a performance improvement of up to 4.68%compared to the average accuracy of the entire model.

关键词： Image classification deep learning CNNs hierarchical ensemble UC-Merced land use dataset contour image

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A Delayed Stochastic Volatility Correction to the Constant Elasticity of Variance Model

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Acta Mathematicae Applicatae Sinica 2016年第3期32卷 611-622页

作者： Min-Ku LEE jeong-Hoon kim Department of Mathematics Kunsan National University Department of Mathematics Yonsei University

The Black-Scholes model does not account non-Markovian property and volatility smile or skew although asset price might depend on the past movement of the asset price and real market data can find a non-flat structure of the implied volatility surface. So, in this paper, we formulate an underlying asset model by adding a delayed structure to the constant elasticity of variance （CEV） model that is one of renowned alternative models resolving the geometric issue. However, it is still one factor volatility model which usually does not capture full dynamics of the volatility showing discrepancy between its predicted price and market price for certain range of options. Based on this observation we combine a stochastic volatility factor with the delayed CEV structure and develop a delayed hybrid model of stochastic and local volatilities. Using both a martingale approach and a singular perturbation method, we demonstrate the delayed CEV correction effects on the European vanilla option price under this hybrid volatility model as a direct extension of our previous work [12].

关键词： constant elasticity variance , delay stochastic volatility martingale option pricing

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Data Augmentation Using Contour Image for Convolutional Neural Network

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Computers, Materials & Continua 2023年第6期75卷 4669-4680页

作者： Seung-Yeon Hwang jeong-Joon kim Department of Computer Engineering Anyang UniversityAnyang-si14058Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14058Korea

With the development of artificial intelligence-related technologies such as deep learning,various organizations,including the government,are making various efforts to generate and manage big data for use in artificial ***,it is difficult to acquire big data due to various social problems and restrictions such as personal information *** are many problems in introducing technology in fields that do not have enough training data necessary to apply deep learning ***,this study proposes a mixed contour data augmentation technique,which is a data augmentation technique using contour images,to solve a problem caused by a lack of ***,a famous convolutional neural network(CNN)architecture,and CIFAR-10,a benchmark data set,are used for experimental performance evaluation to prove the superiority of the proposed *** to prove that high performance improvement can be achieved even with a small training dataset,the ratio of the training dataset was divided into 70%,50%,and 30%for comparative *** a result of applying the mixed contour data augmentation technique,it was possible to achieve a classification accuracy improvement of up to 4.64%and high accuracy even with a small amount of data *** addition,it is expected that the mixed contour data augmentation technique can be applied in various fields by proving the excellence of the proposed data augmentation technique using benchmark datasets.

关键词： Data augmentation image classification deep learning convolutional neural network mixed contour image benchmark dataset

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A Universal Activation Function for Deep Learning

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Computers, Materials & Continua 2023年第5期75卷 3553-3569页

作者： Seung-Yeon Hwang jeong-Joon kim Department of Computer Engineering Anyang UniversityAnyang-si14028Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14028Korea

Recently,deep learning has achieved remarkable results in fields that require human cognitive ability,learning ability,and reasoning *** functions are very important because they provide the ability of artificial neural networks to learn complex patterns through *** activation functions are being studied to solve problems such as vanishing gradients and dying nodes that may occur in the deep learning ***,it takes a lot of time and effort for researchers to use the existing activation function in their ***,in this paper,we propose a universal activation function(UA)so that researchers can easily create and apply various activation functions and improve the performance of neural *** can generate new types of activation functions as well as functions like traditional activation functions by properly adjusting three *** famous Convolutional Neural Network(CNN)and benchmark datasetwere used to evaluate the experimental performance of the UA proposed in this *** compared the performance of the artificial neural network to which the traditional activation function is applied and the artificial neural network to which theUA is *** addition,we evaluated the performance of the new activation function generated by adjusting the hyperparameters of *** experimental performance evaluation results showed that the classification performance of CNNs improved by up to 5%through the UA,although most of them showed similar performance to the traditional activation function.

关键词： Deep learning activation function convolutional neural network benchmark datasets universal activation function

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Effects of humic acid on phytodegradation of petroleum hydrocarbons in soil simultaneously contaminated with heavy metals

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Journal of Environmental Sciences 2011年第12期23卷 2034-2041页

作者： Soyoung Park Ki Seob kim jeong-Tae kim Daeseok Kang Kijune Sung Department of Ocean Engineering Pukyong National University Busan 608-737 Korea Department of Ecological Engineering Pukyong National University Busan 608-737 Korea

The use of humic acid （HA） to enhance the efficiency of phytodegradation of petroleum hydrocarbons in soil contaminated with diesel fuel was evaluated in this study. A sample of soil was artificially contaminated with commercially available diesel fuel to an initial total petroleum hydrocarbons （TPH） concentration of 2300 mg/kg and four heavy metals with concentrations of 400 mg/kg for Pb, 200 mg/kg for Cu, 12 mg/kg for Cd, and 160 mg/kg for Ni. Three plant species, Brassica campestris, Festuca arundinacea, and Helianthus annuus, were selected for the phytodegradation experiment. Percentage degradation of TPH in the soil in a control pot supplemented with HA increased to 45% from 30% without HA. The addition of HA resulted in an increases in the removal of TPH from the soil in pots planted with B. campestris, F. arundinacea, and H. annuus, enhancing percentage degradation to 86%, 64%, and 85% from 45%, 54%, and 66%, respectively. The effect of HA was also observed in the degradation of n-alkanes within 30 days. The rates of removal of n-alkanes in soil planted with B. campestris and H. annuus were high for n-alkanes in the range of C11–C28. A dynamic increase in dehydrogenase activity was observed during the last 15 days of a 30-day experimental period in all the pots amended with HA. The enhanced biodegradation performance for TPHs observed might be due to an increase in microbial activities and bioavailable TPH in soils caused by combined effects of plants and HA. The results suggested that HA could act as an enhancing agent for phytodegradation of petroleum hydrocarbons in soil contaminated with diesel fuel and heavy metals.

关键词： phytodegradation TPHs humic acid n-alkanes DHA combined effects

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Nanocrystalline low-silica X zeolite as an efficient ion-exchanger enabling fast radioactive strontium capture

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Frontiers of Chemical Science and Engineering 2024年第9期18卷 15-23页

作者： Hyungmin Jeon Susung Lee jeong-Chul kim Minkee Choi Department of Chemical and Biomolecular Engineering(BK21 Four) Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Center for Nanomaterials and Chemical Reactions Institute for Basic Science(IBS)Daejeon 34141Republic of Korea

NaA zeolite(Si/Al=1.00)has been commercially applied for capturing radioactive 90Sr^(2+)because of its high surface charge density,effectively stabilizing the multivalent ***,owing to its narrow micropore opening(4.0Å),large micron-sized crystallites,and bulkiness of hydrated Sr^(2+),the Sr^(2+)exchange over NaA has been limited by very slow *** this study,we synthesized nanocrystalline low-silica X by minimizing a water content in a synthesis gel and utilizing a methyl cellulose hydrogel as a crystal growth *** resulting zeolite exhibited high crystallinity and Al-rich framework(Si/Al of approximately 1.00)with the sole presence of tetrahedral Al sites,which are capable of high Sr^(2+)uptake and ion ***,the zeolite with a FAU topology has a much larger micropore opening size(7.4Å)and a much smaller crystallite size(~340 nm)than NaA,which enable significantly enhanced ion-exchange *** to conventional NaA,the nanocrystalline low-silica X exhibited remarkably increased Sr^(2+)-exchange kinetics(>18-fold larger rate constant)in batch *** both the nanocrystalline low-silica X and NaA exhibited comparable Sr^(2+)capacities under equilibrated conditions,the former demonstrated a 5.5-fold larger breakthrough volume than NaA under dynamic conditions,attributed to its significantly faster Sr^(2+)-exchange kinetics.

关键词： Sr^(2+)removal low-silica X zeolite nanocrystal hydrogel methyl cellulose

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