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Boosting overall water splitting by incorporating sulfur into NiFe(oxy)hydroxide

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Journal of Energy Chemistry 2022年第1期31卷 364-371,I0010页

作者： Chiho kim Seong Hyun kim Seunghun Lee Ilyeong Kwon Seong Hyun kim Shinho kim Changgyu Seok Yoo Sei Park Yangdo kim Department of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea BK21 Four Innovative Graduate Education Program for Global High-tech Materials&PartsPusan National UniversityBusan 46241Republic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH).Pohang 37673Republic of Korea

Developing highly active and cost-effective electrocatalysts for enhancing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a significant challenge for overall water ***-incorporated nickel iron(oxy)hydroxide(S-NiFeOOH)nanosheets were directly grown on commercial nickel foam using a galvanic corrosion method and a hydrothermal *** incorporation of sulfur into NiFeOOH enhanced the catalytic activity for the HER and OER in 1 M KOH *** enhanced catalytic activity is attributed to the change in the local structure and chemical states due to the incorporation of *** performance for overall water splitting was achieved with an alkaline water *** was realized by employing S-NiFeOOH as a bifunctional electrocatalyst,thereby outperforming a water electrolyzer that requires the usage of precious metal electrocatalysts(i.e.,Pt/C as the HER electrocatalyst and IrO_(2) as the OER electrocatalyst).Moreover,when driven by a commercial silicon solar cell,an alkaline water electrolyzer that uses S-NiFeOOH as a bifunctional electrocatalyst generated hydrogen under natural *** study shows that S-NiFeOOH is a promising candidate for a large-scale industrial implementation of hydrogen production for overall water splitting because of its low cost,high activity,and *** addition,the solar-driven water electrolyzer using S-NiFeOOH as a bifunctional electrocatalyst affords the opportunity for developing effective and feasible solar power systems in the future.

关键词： Overall water splitting Hydrogen production Sulfur incorporated NiFe(oxy)hydroxide Electrocatalysts Solar-driven water splitting

Characterization of Ceramic Composite-Membranes Prepared by ORMOSIL Coating Sol

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Journal of Rare Earths 2004年第z2期22卷 136-140页

作者： Goo-Dae kim Tae-Bong kim School of New Materials Science and Engineering Yonsei UniversitySeoul 120-749Korea Division of MaterialsKorea Institute Science and TechnologySeoul 136-791Korea

Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under different molecular weight of polymer species [polyethylene glycol (PEG) ] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol (PEG)]. The properties of as-prepared ormosil sol such as,viscosity, gelation time were characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its micro-structure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross-flow apparatus. The ormosil sol coated Membrane is easily formed by steric effect of polymer and it improves flux efficiency because infiltration into porous support decreased. Its flux efficiency is elevated about 200(1/m2·h) compared with colloidal sol coated membrane at point of five minutes from starting test.

关键词： ORMOSIL sol crack Resistance ultra-filter micro-filter

Dragonfly Interaction Algorithm for Optimization of Queuing Delay in Industrial Wireless Networks

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Journal of Bionic Engineering 2024年第1期21卷 447-485页

作者： Sanjay Bhardwaj Da-Hye kim Dong-Seong kim Department of IT Convergence Engineering ICT Convergence Research CenterKumoh National Institute of TechnologyGumiSouth Korea

In industrial wireless networks,data transmitted from source to destination are highly *** often leads to the queuing of the data,and poor management of the queued data results in excessive delays,increased energy consumption,and packet ***,a nature-inspired-based Dragonfly Interaction Optimization Algorithm(DMOA)is proposed for optimization of the queue delay in industrial wireless *** term“interaction”herein used is the characterization of the“flying movement”of the dragonfly towards damselflies(female dragonflies)for *** a result,interaction is represented as the flow of transmitted data packets,or traffic,from the source to the base *** includes each and every feature of dragonfly movement as well as awareness of the rival dragonflies,predators,and damselflies for the desired optimization of the queue *** features are juxtaposed as noise and interference,which are further used in the calculation of industrial wireless metrics:latency,error rate(reliability),throughput,energy efficiency,and fairness for the optimization of the queue *** analysis,convergence analysis,the Wilcoxon test,the Friedman test,and the classical as well as the 2014 IEEE Congress of Evolutionary Computation(CEC)on the benchmark functions are also used for the evaluation of DMOA in terms of its robustness and *** results demonstrate the robustness of the proposed algorithm for both classical and benchmarking functions of the IEEE CEC ***,the accuracy and efficacy of DMOA were demonstrated by means of the convergence rate,Wilcoxon testing,and ***,fairness using Jain’s index in queue delay optimization in terms of throughput and latency,along with computational complexity,is also evaluated and compared with other *** results show that DMOA exceeds other bio-inspired optimization algorithms in terms of fairness in queue delay management and average packet *** proposed a

关键词： Dragonfly Damselfly Interaction Queuing delay Optimization Industrial wireless networks

Detecting IoT Botnet in 5G Core Network Using Machine Learning

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Computers, Materials & Continua 2022年第9期72卷 4467-4488页

作者： Ye-Eun kim Min-Gyu kim Hwankuk kim Department of Electronics Information and System Engineering Sangmyung UniversityCheonan-siKorea Department of Information Security Engineering Sangmyung UniversityCheonan-siKorea

As Internet of Things(IoT)devices with security issues are connected to 5G mobile networks,the importance of IoT Botnet detection research in mobile network environments is ***,the existing research focused on AI-based IoT Botnet detection research in wired network *** addition,the existing research related to IoT Botnet detection in ML-based mobile network environments have been conducted up to ***,this paper conducts a study on ML-based IoT Botnet traffic detection in the 5G core *** binary and multiclass classification was performed to compare simple normal/malicious detection and normal/threetype IoT Botnet malware *** both classification methods,the IoT Botnet detection performance using only 5GC’s GTP-U packets decreased by at least 22.99%of accuracy compared to detection in wired network *** addition,by conducting a feature importance experiment,the importance of feature study for IoT Botnet detection considering 5GC network characteristics was *** this paper analyzed IoT botnet traffic passing through the 5GC network using ML and presented detection results,think it will be meaningful as a reference for research to link AI-based security to the 5GC network.

关键词： IoT botnet 5G B5G malware machine learning

Copper telluride with manipulated carrier concentrations for high-performance solid-state thermoelectrics

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Journal of Materials Science & Technology 2022年第34期129卷 190-195页

作者： Hyun Ju Dabin Park Minsu kim Jooheon kim G.W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA School of Chemical Engineering&Materials Science Chung-Ang UniversitySeoul 06974Republic of Korea Department of Intelligent Energy and Industry Graduate SchoolChung-Ang UniversitySeoul 06974Republic of Korea Department of Advance Materials Engineering Chung-Ang UniversityAnseong 17546Republic of Korea

This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.

关键词： Thermoelectric Copper telluride Graphene Carrier concentration Single parabolic band model

Flow Characteristics in Compact Thermal Spray Coating Systems with Minimum Length Nozzle

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Plasma Science and Technology 2009年第5期11卷 550-554页

作者： Seung-Hyun kim Youn-Jea kim School of Mechanical Engineering Sungkyunkwan University

In this study, numerical analysis is performed to adopt the equivalence ratio on the high velocity oxygen fuel （HVOF） thermal spray coating systems equipped with a minimum length nozzle. The analysis is applied to investigate the axisymmetric, steady-state, turbulent, and chemically combusting flow both within the torch and in a free jet region between the torch and the substrate to be coated. The combustion is modeled using a single-step and eddy-dissipation model which assumes that the reaction rate is limited by the turbulent mixing rate of the fuel and oxidant. As the diameter of the nozzle throat is increased, the location of the Mach shock disc moves backward from the nozzle exit. As the throat diameter and the divergent portion are 6 mm and 8 mm, respectively, the pressure in the HVOF system is the lowest at the chamber and the expanding gas is steadily maintained with both high velocity and high temperature for different equivalence ratios. Thus, relatively minor amendments of the equivalence ratio and the geometry of HVOF can lead to improved control over coating characteristics.

关键词： minimum length nozzle HVOF equivalence ratio

Fabrication of Piezoelectric Cellulose Paper and Audio Application

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Journal of Bionic Engineering 2009年第1期6卷 18-21页

作者： Jung-Hwan kim Sungryul Yun Joo-Hyung kim Jaehwan kim Creative Research Center for EAPap Actuator Department of Mechanical EngineeringINHA University253 Young-Hyun DongNam GuIncheon402-751Republic of Korea

We report the fabrication process of piezoelectric cellulose paper and the enhancement method of its piezoelectric property. Stretching method with different wet-drawing ratios was introduced to increase the piezoelectric property of cellulose paper during regeneration *** is observed that the Young's modulus and the piezoelectric charge constants are very dependent on the drawing ratio and the direction of nanofibrils of piezoelectric *** the enhanced piezoelectric property,we prove that the flexible regenerated piezoelectric cellulose can be applied to the potential acoustic applications such as thin piezoelectric paper speaker.

关键词： piezoelectric speaker piezoelectricity cellulose wet-drawing process

Microstructure and texture evolution of Ti-Nb-Si based alloys for biomedical applications

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Rare Metals 2006年第z2期25卷 163-167页

作者： kim Won-Yong kim Han-Sol Advanced Materials R&D Division Korea Institute of Industrial Technology Incheon 406-130 Korea

Microstructure and texture of Ti-Nb-Si based alloys, prepared by water quenching from β-phase field, cold rolling and recrystallization heat treatment followed by water quenching, were investigated in terms of optical microstructure and analysis of X-ray pole figure result. In as-quenched sample, relatively random distribution of pole figure was detected without showing a specific texture component. In as-cold rolled sample, however, it is found well-developed several texture components consisting of rotated cube, α-fiber and γ-fiber texture components which are frequently observed in bcc-structured metals and alloys were found. Therefore, texture components developed in the present alloys are closely related to the deformation of β-phase even though small amount of α″ phase co-exist in the microstructure. In recrystallized sample, α-fiber texture component is weakly detected while the other texture components, rotated cube and γ-fiber components, appears to be relatively unchanged. No additional texture components were detected besides those texture components observed in the cold rolled samples.

关键词： Ti-Nb-Si based alloys microstructure texture

Sandwich-type ordered mesoporous carbon/graphene nanocomposites derived from ionic liquid

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Nano Research 2016年第9期9卷 2696-2706页

作者： Ho Seok kim Young Hwan kim Kwang Chul Roh Kwang-Bum kim Lab of Energy Storage Materials Department of Material Science & EngineeringYonsei UniversitySeou1120749Republic of Korea Energy & Environmental Division Korea Institute of Ceramic Engineering & TechnologyJinju 52851Republic of Korea

Sandwich-type ordered mesoporous carbon/graphene nanocomposites were successfully synthesized using 2D ordered mesoporous silica/graphene nanocomposites as the hard template and an ionic liquid as a N-rich carbon source. We used an ionic liquid of 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide containing nitrile groups (–CN) in the cation and anion as a carbon precursor for the preparation of the nanocomposites. Nitriles do not decompose under thermal treatment in an inert gas atmosphere, but leave significant amounts of N-rich carbon materials. The nanocomposites had a large surface area (1,316 m2·g–1), an average pore diameter of 5.9 nm, and high electrical conductivity. The nanocomposite electrode showed a high specific capacitance of 190 F·g–1at 0.5 A·g–1in 1 M TEABF4/AN electrolyte and a good rate capability between 0 and 2.7 V for supercapacitor (or ultracapacitor) applications. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： ionic liquid-derived carbon ordered mesoporous carbon/graphene nanocomposite 2D graphene nanocomposite supercapacitor