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Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief

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Friction 2023年第7期11卷 1292-1306页

作者： Kuk-Jin SEO Hyun-joon KIM Dae-eun KIM Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Precision Mechanical Engineering Kyungpook National UniversitySangju 37224Republic of Korea Department of Advanced Science and Technology Convergence Kyungpook National UniversitySangju 37224Republic of Korea

This work shows that a soft,thin film comprising randomly aligned carbon nanotubes(CNTs)can reduce surface wear more effectively than a homogeneous thin film because of enhanced elastic recoverability and contact stress relief originating from its mesh *** investigate the wear characteristics of the mesh structure compared to those of the homogeneous thin film,multi-walled CNTs(MWCNTs)and diamond-like carbon(DLC)thin films were prepared to conduct nanoscale tribological experiments using the atomic force microscopy(AFM).The MWCNT thin film showed unmeasurably low wear compared with the DLC thin film under a certain range of normal *** demonstrate the wear reduction mechanism of the MWCNT thin film,its indentation and frictional behaviors were *** indentation behavior of the MWCNT thin film revealed repetitive elastic deformation with a wide strain range and a significantly lower elastic modulus than that of the DLC thin *** permanent deformation of the MWCNT thin film was observed through frictional experiments under relatively high normal load *** results are expected to provide insights into the design of highly wear-resistant surfaces using nanostructures.

关键词： carbon nanotube(CNT) thin film wear friction elastic recovery

Electrophoretic deposition of a supercapacitor electrode of activated carbon onto an indium-tin-oxide substrate using ethyl cellulose as a binder

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Journal of Materials Science & Technology 2020年第23期58卷 188-196页

作者： Taeuk Kim Seong-Hoon Yi Sang-eun chun School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

A transparent energy storage device is an essential component for transparent *** increasing demand for high-power devices stimulates the development of transparent supercapacitors with high power density.A transparent electrode for such supercapacitors can be assembled via the electrophoretic deposition of an active material powder with a binder onto a transparent *** properties of the binder critically influence the electrochemical behavior and performance of the resulting *** cellulose(EC)is known as an eco-friendly,transparent,flexible,and inexpensive ***,we fabricated an electrode film with EC binder via electrophoretic deposition on an indium tin oxide(ITO)substrate instead of using the conventional polytetrafluoroethylene(PTFE)*** assembled electrodes with EC and PTFE were compared to investigate the feasibility of EC as a binder from different perspectives,including homogeneity,wettability,electrochemical behavior,and mechanical *** EC enabled the formation of a homogeneous film composed of smaller particles and with a higher specific capacitance compared with films prepared with *** annealing improved the adhesion strength of the EC because of its glass transition;however,its hydrophobic nature limited utilization of the active material for charge *** electrochemical activation improved the wettability of the electrode,resulting in an increased capacitance of 60 F g^(-1).Furthermore,even with the lower wettability of EC compared with that of PTFE,better rate performance was possible with the EC *** increased mechanical stability after the annealing process ensured an excellent cycle life of 95%capacitance retention for 15,000 cycles.

关键词： Electrophoretic deposition Transparent electrode Activated carbon Ethyl cellulose Indium tin oxide

Byte Frequency Based Indicators for Crypto-Ransomware Detection from Empirical Analysis

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Journal of Computer Science & Technology 2022年第2期37卷 423-442页

作者： Geun Yong Kim joon-Young Paik Yeongcheol Kim eun-Sun Cho Department of Computer Science and Engineering Chungnam National UniversityDaejeon 34134South Korea School of Computer Science and Technology Tiangong UniversityTianjin 300387China

File entropy is one of the major indicators of crypto-ransomware because the encryption by ransomware increases the randomness of file ***,entropy-based ransomware detection has certain limitations;for example,when distinguishing ransomware-encrypted files from normal files with inherently high-level entropy,misclassification is very *** addition,the entropy evaluation cost for an entire file renders entropy-based detection impractical for large *** this paper,we propose two indicators based on byte frequency for use in ransomware detection;these are termed EntropySA and DistSA,and both consider the interesting characteristics of certain file subareas termed“sample areas”(SAs).For an encrypted file,both the sampled area and the whole file exhibit high-level randomness,but for a plain file,the sampled area embeds informative structures such as a file header and thus exhibits relatively low-level randomness even though the entire file exhibits high-level *** and DistSA use“byte frequency”and a variation of byte frequency,respectively,derived from sampled *** indicators cause less overhead than other entropy-based detection methods,as experimentally proven using realistic ransomware *** evaluate the effectiveness and feasibility of our indicators,we also employ three expensive but elaborate classification models(neural network,support vector machine and threshold-based approaches).Using these models,our experimental indicators yielded an average Fl-measure of 0.994 and an average detection rate of 99.46%for file encryption attacks by realistic ransomware samples.

关键词： computer security cryptography machine learning ransomware

Environmentally adaptive reshaping of plant photomorphogenesis by karrikin and strigolactone signaling

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Journal of Integrative Plant Biology 2024年第5期66卷 865-882页

作者： Young-joon Park Bo eun Nam chung-Mo Park Department of Smart Farm Science Kyung Hee UniversityYongin 17104Korea Departmentof Biological Sciences Seoul National UniversitySeoul 08826Korea Department of Chemistry Seoul National UniversitySeoul 08826Korea

Coordinated morphogenic adaptation of growing plants is critical for their survival and propagation under fluctuating *** morphogenic responses to light and warm temperatures,termed photomorphogenesis and thermomorphogenesis,respectively,have been extensively studied in recent *** photomorphogenesis,plants actively reshape their growth and developmental patterns to cope with changes in light ***,photomorphogenesis is closely associated with diverse growth hormonal ***,accumulating evidence indicates that light-directed morphogenesis is profoundly affected by two recently identified phytochemicals,karrikins(KARs)and strigolactones(SLs).KARs and SLs are structurally related butenolides acting as signaling molecules during a variety of developmental steps,including seed *** receptors and signaling mediators have been identified,and associated working mechanisms have been explored using gene-deficient mutants in various plant *** particular interest is that the KAR and SL signaling pathways play important roles in environmental responses,among which their linkages with photomorphogenesis are most comprehensively studied during seedling *** this review,we focus on how the phytochemical and light signals converge on the optimization of morphogenic *** also discuss molecular mechanisms underlying the signaling crosstalks with an aim of developing potential ways to improve crop productivity under climate changes.

关键词： karrikins morphogenic adaptation photomorphogenesis seedling establishment strigolactones

Analysis of the current density characteristics in through-mask electrochemical micromachining(TMEMM) for fabrication of micro-hole arrays on invar alloy film

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Chinese Journal of Aeronautics 2017年第3期30卷 1231-1241页

作者： Da-som JIN Kwang-ho chun eun-sang LEE School of Mechanical Engineering Inha University Incheon 22212 Republic of Kore Department of Mechanical Engineering Inha University Incheon 22212 Republic of Korea

Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes（OLEDs） because of its low thermal expansion coefficient（1.86 × 10^-6cm/°C）.To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining（TMEMM） was developed and combined with a portion of the photolithography etching *** precise hole shapes,patterned photoresist（PR） film was applied as an insulating *** investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the *** finite element method（FEM） was used to verify the influence of each parameter on the current density on the invar alloy film *** parameters considered were the thickness of the PR mask,inter-electrode gap（IEG）,and electrolyte *** of experiments（DOE） was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current *** was conducted to select the suitable *** experiment was carried out to verify the simulation *** was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.

关键词： Electrochemical Invar alloy film Micromachining OLED shadow mask Photoresist film mask(PR film mask) Through-mask electrochemical micromachining(TMEMM)

Enhanced stability and rate performance of zinc-doped cobalt hexacyanoferrate (CoZnHCF) by the limited crystal growth and reduced distortion

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Journal of Energy Chemistry 2022年第6期31卷 649-658,I0018页

作者： Jihwan Kim Seong-Hoon Yi Li Li Sang-eun chun School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina School of Industrial Technology Advances Kyungpook National UniversityDaegu 41566Republic of Korea

Cobalt hexacyanoferrate (CoHCF) is a potential cathode for aqueous Na-ion batteries due to its high theoretical specific capacity (170 m Ah g^(-1));however,its lower rate capability and cyclability limit its *** distortion at a weak N-coordinated crystal field during cycling disintegrates Co,yielding an irreversible *** Zn amounts ranging 0–1 were added to the Co site to suppress the structural irreversibility of CoHCF,yielding Co_(1-x)Zn_(x)HCF powder;this Zn (x≤0.09) addition reduced the powder’s dimension because the lower four coordination of Zn–N,not the six coordination of Co–N,limits the powder ***,a small lattice parameter and interaxial angle (~90°) are obtained,implying that a narrower Co_(1-x)Zn_(x)HCF inner structure is formed to accommodate Na ***,the electronic conductivity of Co_(1-x)Zn_(x)HCF gradually increased within 0–0.09 range.A smaller particle size with a high surface area leads to a near-surface-limited redox process,similar to a capacitive *** the surface-limited reaction and electronic conductivity enhances the reversibility due to the smaller charge transfer resistance at the electrode/electrolyte interface caused by Zn *** redox-active Co with non-active Zn amount of 0.07 (Co_(1-x)Zn_(x)HCF) slightly reduces the specific capacity from 127 to 119 mAh g^(-1)at 0.1 A g^(-1)due to the shrunken Co charging *** performance is enhanced by compromising the capacity and reduced distortion,resulting in 81%retention at a 20-times-faster charging ***,the Co_(1-x)Zn_(x)HCF sample exhibited the good stability while preserving 74%of the initial capacity at 0.5 A g^(-1)after 200 cycles.

关键词： Cobalt hexacyanoferrate Rate capability Stability Growth limitation Structural distortion Near-surface-limited redox process

A Study of the Gas Flow through Air Jet Loom

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Journal of Thermal Science 2007年第2期16卷 159-163页

作者： Heuy-Dong Kim Chae-Min Lim Ho-joon Lee Doo-Hwan chun School of Mechanical Engineering Andong National University388Songcheon-dongAndong 760-749KoreaE-mail:kimhd Korea Textile Machinery Research Institute 300Sampoong-dongKyeongsan 712-210Korea

Air jet loom, as one of the shuttleless looms, transports a yam into warps using viscosity and kinetic energy of an air jet. Performance of this picking system depends on the ability of instantaneous inhalation/exhaust, configuration of nozzle, operation characteristics of a check valve, etc. In the recent past, many studies have been reported on the air jet discharged from a nozzle exit, but studies for understanding the flow field characteristics associated with shear layer and shock wave/boundary layer interaction in the nozzle were not conducted enough. In this paper, a computational study was performed to explain the flow field in the air jet nozzle with an acceleration tube and validated with previous experimental data available. The results obtained from the computational study show that, in the supersonic flow regime, the flow field depends significantly on the length of acceleration tube. As nozzle pressure ratio increases, drag force acting on the string also increases. For a longer acceleration tube, the total pressure loss is large, owing to the frictional loss.

关键词： compressible flow nozzle shear layer shock wave air jet loom shuttleless loom

An Efficient and Spam-Robust Proximity Measure Between Communication Entities

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Journal of Computer Science & Technology 2013年第2期28卷 394-400页

作者： Joo Hyuk Jeon Jihwan Song Jeong eun Kwon Yoon joon Lee Man Ho Park Myoung Ho Kim Department of Computer Science Korea Advanced Institute of Science and Technology Biz Solution Team SK Telecom Information Technology R&D Center Mobile Communication Convergence Research Team Electronics and Telecommunications Research Institute

Electronic communication service providers are obliged to retain communication data for a certain amount of time by their local laws. The retained communication data or the communication logs are used in various applications such as crime detection, viral marketing, analytical study, and so on. Many of these applications rely on effective techniques for analyzing communication logs. In this paper, we focus on measuring the proximity between two communication entities, which is a fundamental and important step toward further analysis of communication logs, and propose a new proximity measure called ESP （Efficient and Spam-Robust Proximity measure）. Our proposed measure considers only the （graph- theoretically） shortest paths between two entities and gives small values to those between spam-like entities and others. Thus, it is not only computationally efficient but also spam-robust. By conducting several experiments on real and synthetic datasets, we show that our proposed proximity measure is more accurate, computationally efficient and spam-robust than the existing measures in most cases.

关键词： proximity closeness spam electronic communication

Enhancement of photoresponsive electrical characteristics of multilayer MoS2 transistors using rubrene patches

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Nano Research 2015年第3期8卷 790-800页

作者： eun Hei Cho Won Geun Song Cheol joon Park Jeongyong Kim Sunkook Kim Jinsoo Joo Department of Physics Korea University Seou1136-713 R. O. Korea Department of Electronics and Radio Engineering Institute for Laser Engineering Kyung Hee University Yongin Gyeonggi-do 446-70 I R. O. Korea Center for Integrated Nanostructure Physics (CINAP) Institute for Basic Science (IBS) Department of Energy Science Sungkyunkwan University Suwon 440-746 R. O. Korea

Multilayer MoS2 is a promising active material for sensing, energy harvesting, and optoelectronic devices owing to its intriguing tunable electronic band structure. However, its optoelectronic applications have been limited due to its indirect band gap nature. In this study, we fabricated a new type of phototransistor using multilayer MoS2 crystal hybridized with p-type organic semiconducting rubrene patches. Owing to the outstanding photophysical properties of rubrene, the device characteristics such as charge mobility and photoresponsivity were considerably enhanced to an extent depending on the thickness of the rubrene patches. The enhanced photoresponsive conductance was analyzed in terms of the charge results of the nanoscale laser confocal time-resolved PL measurements. transfer doping effect, validated by the microscope photoluminescence （PL） and

关键词： MoS2 rubrene transistor photoresponsivity charge transfer