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Journal of Energy Chemistry 2021年第6期30卷 10-18,I0001页

作者： Yoongon kim Yuseong Noh Jaejin Bae Hyunwoo Ahn Minho kim Won Bae kim Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohang 37673South Korea

Lithium-sulfur(Li-S)batteries have attracted considerable attention as next-generation energy storage devices owing to their high theoretical specific capacity and ***,the commercialization of Li-S batteries is hindered by critical issues,including the migration of the dissolved lithium polysulfides(LiPSs)from the sulfur electrode to the lithium metal anode,resulting in poor cycling ***,we report a multifunctional interlayer configured with an N-doped carbon framework and titanium nitride nanowires on a polypropylene separator(NC/TiN NWs@PP)to suppress the polysulfide shuttling ***/TiN NWs@PP can be obtained by electrospinning and the subsequent scalable solution-based vacuum *** one-dimensional structure of the TiN NWs can shorten the Li-ion diffusion distance with large electrode/electrolyte ***,the N-doped carbon framework in the NWs enables facile electron transportation and allows the suppression of the shuttle effect to improve the electrochemical reaction *** Li-S battery with a NC/TiN NWs@PP separator exhibited enhanced cycling stability and rate capability,indicating that this could be a new research direction for Li-S batteries.

关键词： Li-S battery Shuttle effect Interlayer Separator TiN N-doped carbon 1D Nanowire

A systematic correlation between morphology of porous carbon cathode and electrolyte in lithium-sulfur battery

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Journal of Energy Chemistry 2021年第10期30卷 561-573,I0014页

作者： Jihyeon Park Seoyoung Yoon Seoyeah Oh Jiyoon kim Dongjun kim Geonho kim Jiyeon Lee Myeong Jun Song Ilto kim Kwonnam Sohn Jiwon kim School of Integrated Technology College of EngineeringYonsei University85 Songdogwahak-roYeonsu-guIncheon 21983Republic of Korea Integrated Science and Engineering Division Underwood International CollegeYonsei University85 Songdogwahak-roYeonsu-guIncheon 21983Republic of Korea Integrated Biotechnology and Translational Medicine Graduate SchoolYonsei University85 Songdogwahak-roYeonsu-guIncheon 21983Republic of Korea LG Chem. LG Science Park30 Magokjungang 10-roGangseo-guSeoul 07796Republic of Korea

Porous carbon has been applied for lithium-sulfur battery cathodes,and carbonized metal-organic framework(MOF)is advantageous in tuning the ***,we have systematically synthesized water-distorted MOF(WDM)derived porous carbon via controlling the proportion of both water in a mixed solvent(dimethylformamide and water)and ligand in MOF-5 precursors(metal and ligand),which is categorized by its morphology(*** stone(closed),Tassel(open)and Intermediate(semi-open)).For example,decrease in water and increase in ligand content induce Cracked stone WDMs which showed the highest specific surface area(2742-2990 m^(2)/g)and pore volume(2.81-3.28 cm^(3)/g)after *** effect of carbonized WDMs(CWDMs)on battery performance was examined by introducing electrolytes with different sulfur reduction mechanisms(***/DME and ACN_(2) LiTFSITTE):Closed framework effectively confines polysulfide,whereas open framework enhances electrolyte *** initial capacities of the batteries were in the following order:Cracked stone>Intermediate>Tassel for DOL/DME and Intermediate>Tassel>Cracked stone for ACN_(2) *** note,Intermediate CWDM exhibited the highest initial capacity and retained capacity after 100 cycles(1398 and 747 mAh/g)in ACN_(2) LiTFSI-TTE electrolyte having advantages from both open and closed *** sum,we could correlate cathode morphology(openness and pore structure)and electrolyte type(*** solubility)with lithium-sulfur battery performance.

关键词： Lithium-sulfur battery Metal-organic framework Hierarchical porous carbon cathode Morphology control Electrolyte Lithium polysulfide solubility

A Novel Transparent and Auditable Fog-Assisted Cloud Storage with Compensation Mechanism

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Tsinghua Science and Technology 2020年第1期25卷 28-43页

作者： Donghyun kim Junggab Son Daehee Seo Yeojin kim Hyobin kim Jung Taek Seo Department of Computer Science Kennesaw State UniversityMariettaGA 30060USA Department of Information Security Engineering Soonchunhyang UniversityAsan 31538South Korea

This paper introduces a new fog-assisted cloud storage which can achieve much higher throughput compared to the traditional cloud-only storage architecture by reducing the traffics toward the cloud storage. The fog-storage service providers are transparency to end-users and therefore, no modification on the end-user devices is necessary. This new system is featured with(1) a stronger audit scheme which is naturally coupled with the proposed architecture and does not suffer from the replay attack and(2) a transparent and efficient compensation mechanism for the fog-storage service providers. We provide rigorous theoretical analysis on the correctness and soundness of the proposed system. To the best of our knowledge, this is the first paper to discuss about a storage data audit scheme for fog-assisted cloud storage as well as the compensation mechanism for the service providers of the fog-storage service providers.

关键词： fog computing cloud computing network storage data audit merkle hash tree integer factorization payment transparency

DYNAMIC PROPERTIES OF AL-ALLOY FOAM BEAM DAMAGED BY COMPRESSIVE FATIGUE

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Acta Mechanica Solida Sinica 2008年第3期21卷 241-246页

作者： Sung-Gaun kim Ilhyun kim Amkee kim Seung-Joon kim Junhong Park Division of Mechanical and Automotive Engineering Kongju National University 275 Budae-dongCheonan Chungnam 330-717 Korea Department of Mechanical Engineering Hanyang University Seongdong-Gu Seoul 133-791 Korea

The permanent residual strain in aluminum （Al） alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles. Consequently, the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam. In this paper, the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied. The beam specimens with various residual strains were made by cyclic compression-compression stress. The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method. As a result, the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam. The loss factor shows a manifest dependence on the fatigue residual strain.

关键词： Aluminum foam fatigue dynamic stiffness loss factor

Some identities of Bell polynomials

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Science China Mathematics 2015年第10期58卷 2095-2104页

作者： kim Dae San kim Taekyun Department of Mathematics Sogang University Department of Mathematics Kwangwoon University

We investigate Bell polynomials, also called Touchard polynomials or exponential polynomials, by using and without using umbral calculus. We use three different formulas in order to express various known families of polynomials such as Bernoulli polynomials, poly-Bernoulli polynomials, Cauchy polynomials and falling factorials in terms of Bell polynomials and vice versa. In addition, we derive several properties of Bell polynomials along the way.

关键词： Bell-polynomial umbral calculus poly-Bernoulli polynomial higher-order Bernoulli polynomial Cauchy polynomial

Network-Aided Intelligent Traffic Steering in 5G Mobile Networks

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Computers, Materials & Continua 2020年第10期65卷 243-261页

作者： Dae-Young kim Seokhoon kim School of Computer Software Daegu Catholic UniversityGeyongsan38430Korea Department of Computer Software Engineering Soonchunhyang UniversityAsan31538Korea

Recently,the fifth generation(5G)of mobile networks has been deployed and various ranges of mobile services have been *** 5G mobile network supports improved mobile broadband,ultra-low latency and densely deployed massive *** allows multiple radio access technologies and interworks them for services.5G mobile systems employ traffic steering techniques to efficiently use multiple radio access ***,conventional traffic steering techniques do not consider dynamic network conditions *** this paper,we propose a network aided traffic steering technique in 5G mobile network architecture.5G mobile systems monitor network conditions and learn with network *** a machine learning algorithm such as a feed-forward neural network,it recognizes dynamic network conditions and then performs traffic *** proposed scheme controls traffic for multiple radio access according to the ratio of measured ***,it can be expected to improve traffic steering *** performance of the proposed traffic steering scheme is evaluated using extensive computer simulations.

关键词： Mobile network 5G traffic steering machine learning MEC

A Data Download Method from RSUs Using Fog Computing in Connected Vehicles

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Computers, Materials & Continua 2019年第5期59卷 375-387页

作者： Dae-Young kim Seokhoon kim School of Information Technology Daegu Catholic UniversityGyeongsan-si 38430Republic of Korea Department of Computer Software Engineering Soonchunhyang UniversityAsan-si 31538Republic of Korea

Communication is important for providing intelligent services in connected *** must be able to communicate with different places and exchange information while *** service operation,connected vehicles frequently attempt to download large amounts of *** can request data downloading to a road side unit(RSU),which provides infrastructure for connected *** RSU is a data bottleneck in a transportation system because data traffic is concentrated on the ***,it is not appropriate for a connected vehicle to always attempt a high speed download from the *** the mobile network between a connected vehicle and an RSU has poor connection quality,the efficiency and speed of the data download from the RSU is *** problem affects the quality of the user ***,it is important for a connected vehicle to connect to an RSU with consideration of the network conditions in order to try to maximize download *** proposed method maximizes download speed from an RSU using a machine learning *** collect and learn from network data,fog computing is used.A fog server is integrated with the RSU to perform *** the algorithm recognizes that conditions are not good for mass data download,it will not attempt to download at high ***,the proposed method can improve the efficiency of high speed *** conclusion was validated using extensive computer simulations.

关键词： Connected car fog computing data download DSRC machine learning

Analysis of Imperfect Acoustic Cloaking Resonances

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Chinese Physics Letters 2012年第12期29卷 119-122页

作者： kim Seungil Department of Mathematics and Research Institute for Basic Sciences Kyung Hee UniversitySeoul 130-701Korea

We study the resonance phenomenon arising from imperfect acoustic cloaking in 2D based on a small perturbation of the transformation *** is shown that the resonant frequencies of imperfect cloaking appearing in the total scattering cross section converge to Dirichlet eigenvalues of the concealed region as a perturbation parameter approaches *** theory enables us to predict the location of the resonant frequencies of imperfect cloaking and to identify the corresponding resonance modes.

关键词： perturbation imperfect resonant

Effective Denoising Architecture for Handling Multiple Noises

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Computer Systems Science & Engineering 2023年第3期44卷 2667-2682页

作者： Na Hyoun kim Namgyu kim The Graduate School of Business IT of Kookmin University Seoul02707Korea

Object detection,one of the core research topics in computer vision,is extensively used in various industrial *** there have been many studies of daytime images where objects can be easily detected,there is relatively little research on nighttime *** the case of nighttime,various types of noises,such as darkness,haze,and light blur,deteriorate image ***,an appropriate process for removing noise must precede to improve object detection *** there are many studies on removing individual noise,only a few studies handle multiple noises *** this paper,we pro-pose a convolutional denoising autoencoder(CDAE)-based architecture trained on various types of *** also present various composing modules for each noise to improve object detection performance for night *** the exclusively dark(ExDark)Image dataset,experimental results show that the Sequentialfiltering architecture showed superior mean average precision(mAP)compared to other architectures.

关键词： Object detection computer vision nighttime multiple noises convolutional denoising autoencoder

Identities for degenerate Bernoulli polynomials and Korobov polynomials of the first kind

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Science China Mathematics 2019年第5期62卷 999-1028页

作者： Taekyun kim Dae San kim Department of Mathematics Kwangwoon University Department of Mathematics Sogang University

In this paper, we derive five basic identities for Sheffer polynomials by using generalized Pascal functional and Wronskian matrices. Then we apply twelve basic identities for Sheffer polynomials, seven from previous results, to degenerate Bernoulli polynomials and Korobov polynomials of the first kind and get some new identities. In addition, letting λ→ 0 in such identities gives us those for Bernoulli polynomials and Bernoulli polynomials of the second kind.

关键词： generalized Pascal functional matrix Wronskian matrix degenerate Bernoulli polynomial Krobov polynomial of the first kind