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MXene-based hybrid materials for electrochemical and photoelectrochemical H_(2) generation

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Journal of Energy Chemistry 2024年第6期93卷 111-125,I0004页

作者： Jun young kim Seung Hun Roh Chengkai Xia Uk Sim Jung Kyu kim School of Material Science and Engineering North University of ChinaTaiyuan 030051China School of Chemical Engineering Sungkyunkwan University(SKKU)2066Seobu-roJangan-guSuwon 16419Republic of Korea Hydrogen Energy Technology Laboratory Korea Institute of Energy Technology(KENTECH)NajuJeollanamdo 58330Republic of Korea SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan University(SKKU)2066Seobu-roJangan-guSuwon 16419Republic of Korea

The conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar *** aligns with the increasing global demand for the development of an ideal energy alternative to fossil fuels that does not emit greenhouse ***(EC) and photoelectrochemical(PEC) water splitting technologies have garnered significant attention worldwide for advanced hydrogen solar fuel production in recent *** achieve sustainable green H_(2) production,it is essential to create efficient catalyst materials that are low-cost and can replace expensive noble metal-based *** characteristics make them an ideal catalyst material for the ***-dimensional MXenes with M_(n+1)X_(n) structure have been identified as a promising option for EC and PEC water splitting due to their superior hydrophilicity,metal-like conductivity,large surface area,and adjustable surface ***,we present a summary of recent advancements in the synthesis and performance enhancement methods for MXene hybrid materials in hydrogen production through EC and PEC water ***,we examine the challenges and insights associated with the rational design of MXene-based hybrid materials to facilitate efficient water splitting for sustainable solar fuel production.

关键词： MXene Hybrid materials EC PEC HER OER Water splitting

Joining Technology of Dissimilar Materials for Automotive Components(Ⅱ)

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Journal of Rare Earths 2004年第z2期22卷 35-37页

作者： Meung Ho Rhee Jong Ho Song Woo young Chung young Myoung kim Korea Automotive Technology Institute 74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA Korea Automotive Technology Institute74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA Korea Automotive Technology Institute74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA Korea Automotive Technology Institute74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA

Joining techniques of dissimilar materials for lightweight multi-material automotive body structure were discussed. The joining of 1 .4 mm thickness steel and 2 mm thickness of Al were performed by the new method that is hybrid laser welding system. After aluminum and steel were welded by laser hybrid welding process, the micro-structure investment and the micro-hardness test were carried out. Hybrid laser welding promises a bright future in joining technology of dissimilar materials for automotive components.

关键词： multi-material automotive body dissimilar materials hybrid laser welding

Wave-tide-surge coupled model simulation for Typhoon Maemi

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Acta Oceanologica Sinica 2007年第1期26卷 35-47页

作者： CHOI Byung Ho kim Dong Chule kim young Bok kim Hyun Seung Department of Civil and Environmental Engineering Sungkyunkwan UniversitySuwon 440-746Korea Korean Ocean Science and Engineering Corporation Seoul 152-050Korea

Reasonably accurate predictions of wave heights, current and elevations during storm events are vital information for marine operations and design of offshore and coastal structures in the surrounding seas of Korea Peninsula. Ocean circulation and wind-wave models have traditionally been run separately, but recent researches have identified potentially important interactions between current and wave motions. The coupled tide-surge and the WAM wave models at the atmospheric boundary layer and bottom boundary layer around the Korea Peninsula are applied for the Typhoon Maemi （0314） event. Communication between the models is aehievod using MPI. Results are compared with coastal tide gauges and moored wave buoys and comparisons are also made between wave computations from the coupled model and the independent third generation wave models. Results suggest that applying the fide-surge-coupled model can be an effective means of obtaining wave and storm surge predictions simultaneously.

关键词： wave-tide-surge coupled simulation Typhoon Maemi wave models

Volume Estimation of Small Scale Debris Flows Based on Observations of Topographic Changes Using Airborne LiDAR DEMs

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Journal of Mountain Science 2014年第3期11卷 578-591页

作者： Hosung kim Seung Woo LEE Chan-young YUNE Gihong kim Department of Civil Engineering Gangneung-Wonju National University

This paper describes a geographic information system(GIS)-based method for observing changes in topography caused by the initiation, transport, and deposition of debris flows using highresolution light detection and ranging(LiDAR) digital elevation models(DEMs) obtained before and after the debris flow events. The paper also describes a method for estimating the volume of debris flows using the differences between the LiDAR DEMs. The relative and absolute positioning accuracies of the LiDAR DEMs were evaluated using a real-time precise global navigation satellite system(GNSS) positioning method. In addition, longitudinal and cross-sectional profiles of the study area were constructed to determine the topographic changes caused by the debris flows. The volume of the debris flows was estimated based on the difference between the LiDAR DEMs. The accuracies of the relative and absolute positioning of the two LiDAR DEMs were determined to be ±10 cm and ±11 cm RMSE, respectively, which demonstrates the efficiency of the method for determining topographic changes at an scale equivalent to that of field investigations. Based on the topographic changes, the volume of the debris flows in the study area was estimated to be 3747 m3, which is comparable with the volume estimated based on the data from field investigations.

关键词： Debris flow Topographic change LiDAR DEM Volume estimation Global navigation satellitesystem (GNSS)

Super-resolution localization photoacoustic microscopy using intrinsic red blood cells as contrast absorbers

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Light(Science & Applications) 2019年第1期8卷 212-222页

作者： Jongbeom kim Jin young kim Seungwan Jeon Jin Woo BAIK Seong Hee Cho Chulhong kim Departments of Creative IT Engineering Electrical EngineeringMechanical Engineeringand Interdisciplinary Bioscience and BioengineeringPohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohangGyeongbuk 37673Republic of Korea

Photoacoustic microscopy(PAM)has become a premier microscopy tool that can provide the anatomical,functional,and molecular information of animals and humans in ***,conventional PAM systems suffer from limited temporal and/or spatial ***,we present a fast PAM system and an agent-free localization method based on a stable and commercial galvanometer scanner with a custom-made scanning mirror(L-PAM-GS).This novel hardware implementation enhances the temporal resolution significantly while maintaining a high signal-to-noise ratio(SNR).These improvements allow us to photoacoustically and noninvasively observe the microvasculatures of small animals and humans in ***,the functional hemodynamics,namely,the blood flow rate in the microvasculature,is successfully monitored and quantified in *** importantly,thanks to the high SNR and fast B-mode rate(500 Hz),by localizing photoacoustic signals from captured red blood cells without any contrast agent,unresolved microvessels are clearly distinguished,and the spatial resolution is improved by a factor of 2.5 in ***-GS has great potential in various fields,such as neurology,oncology,and pathology.

关键词： resolution absorber scanner

Spatio-temporal variability in sea surface wind stress near and off the east coast of Korea

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Acta Oceanologica Sinica 2005年第1期24卷 107-114页

作者： NAM SungHyun kim young Ho PARK Kyung-Ae kim Kuh Ocean Laboratory/RIO School of Earth and Environmental Sciences Seoul National University Seoul 151-742 KoreaOcean Laboratory/RIO School of Earth and Environmental Sciences Seoul National University Seoul 151-742 KoreaOcean Laboratory/RIO School of Earth and Environmental Sciences Seoul National University Seoul 151-742 KoreaOcean Laboratory/RIO School of Earth and Environmental Sciences Seoul National University Seoul 151-742 Korea

Sea surface wind stress variabilities near and off the east coast of Korea, are examined using 7 kinds of wind datasets from measurements at 2 coastal (land) stations and 2 ocean buoys,satellite scatterometer (QuikSCAT), and global reanalyzed products (ECMWF,NOGAPS,and NCEP/NCAR). Temporal variabilities are analyzed at 3 frequency bands; synoptic (2-20 d), intra-seasonal (20-90 d),and seasonal (>90 d).Synoptic and intra-seasonal variations are predominant near and off the Donghae City due to the passage of the mesoscale weather system. Seasonal variation is caused by southeastward wind stress during Asian winter monsoon. The sea surface wind stress from reanalyzed *** and KMA-B measurements off the coast show good agreement in the magnitude and direction,which are strongly aligned with the alongshore *** the land-based sites,wind stresses are much weaker by factors of 3-10 due to the mountainous landmass on the east parts of Korea *** first EOF modes(67%-70%) of wind stresses from reanalyzed and QuikSCAT data have similar structures of the strong southeastward wind stress in winter along the coast but show different curl structures at scales less than 200 km due to the orographic *** second EOF modes (23%-25%) show southwestward wind stress in every September along the east coast of the North Korea

关键词： sea surface wind stress spatio-temporal variability monsoon seasonal intra-seasonal synoptic band orographic effect

Voxelated opto-physically unclonable functions via irreplicable wrinkles

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Light(Science & Applications) 2023年第11期12卷 2378-2390页

作者： Kitae kim Se-Um kim Moon-young Choi Mohsin Hassan Saeed youngmin kim Jun-Hee Na Department of Convergence System Engineering Chungnam National University99 Daehak-roYuseong-guDaejeon 34134Republic of Korea Department of Electrical and Information Engineering Seoul National University of Science&Technology232 Gongneung-roNowon-guSeoul 01811Republic of Korea Department of Electrical Electronicsand Communication Engineering EducationChungnam National University99 Daehak-roYuseong-guDaejeon 34134Republic of Korea Hologram Research Center Korea Electronics Technology InstituteWorld Cup buk-ro 54-gilMapo-guSeoul 03924Republic of Korea

The increased prevalence of the Internet of Things(IoT)and the integration of digital technology into our daily lives have given rise to heightened security risks and the need for more robust security *** response to these challenges,physical unclonable functions(PUFs)have emerged as promising solution,offering a highly secure method to generate unpredictable and unique random digital values by leveraging inherent physical ***,traditional PUFs implementations often require complex hardware and circuitry,which can add to the cost and complexity of the *** present a novel approach using a random wrinkles PUF(rw-PUF)based on an optically anisotropic,facile,simple,and cost-effective *** wrinkles contain randomly oriented liquid crystal molecules,resulting in a two-dimensional retardation map corresponding to a complex birefringence ***,our proposed technique allows for customization based on specific requirements using a spatial light modulator,enabling fast *** random wrinkles PUF has the capability to store multiple data sets within a single PUF without the need for physical ***,we introduce a concept called‘polyhedron authentication,’which utilizes three-dimensional information storage in a voxelated random wrinkles *** approach demonstrates the feasibility of implementing high-level security technology by leveraging the unique properties of the rw-PUF.

关键词： hardware functions utilize

A facile synthesis of hierarchical Sn3O4 nanostructures in an acidic aqueous solution and their strong visible- light-driven photocatalytic activity

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Nano Research 2015年第11期8卷 3553-3561页

作者： Hui Song Su-young Son Seul Ki kim Gun young Jung School of Materials Science and Engineering Gwangju Institute of Science and Technology (GIST) Gwangju 500-712 Republic of Korea Carbon Convergence Materials Research Center Institute of Advanced Composite Materials Korea Institute of Science and Technology (KIST) Jeollabuk-do 565-905 Republic of Korea

Hierarchical tin（Ⅲ） oxide, Sn3O4, nanospheres were synthesized via hydrothermal reaction under strongly acidic ambient conditions. The morphology of Sn3O4 varied with decreasing pH. The prickly SnaO4 nanospheres changed into SnaO4 nanospheres covered with single-crystalline nanoplates having a high BET surface area of ca. 55.05 m^2·g^-1 and a band gap of ca. 2.25 eV. Small amounts （0.05 g） of the hierarchical Sn3O4 nanostructures completely decomposed a 30% methyl orange （MO） solution in 100 mL deionized water within 15 min under one sun condition （UV ＋ visible light）. The Sn3O4 photocatalyst exhibited a fast decomposition rate of 1.73 ×10^-1 min^-1, which is a 90.86% enhancement relative to that of the commercially available P25 photocatalyst. The high photocatalytic activity of the hierarchical Sn3O4 nanostructures is attributed to its ability to absorb visible light and its high surface-to-volume ratio.

关键词： Sn3O4 hierarchical structure hydrothermal morphology engineering photocatalyst

Predicting Concrete Compressive Strength Using Deep Convolutional Neural Network Based on Image Characteristics

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Computers, Materials & Continua 2020年第10期65卷 1-17页

作者： Sanghyo Lee Yonghan Ahn Ha young kim Division of Architecture and Civil Engineering Kangwon National UniversitySamcheok-si25913Korea School of Architecture and Architectural Engineering Hanyang University ERICAAnsan-si15588Korea Graduate School of Information Yonsei UniversitySeoul03722Korea

In this study,we examined the efficacy of a deep convolutional neural network(DCNN)in recognizing concrete surface images and predicting the compressive strength of concrete.A digital single-lens reflex(DSLR)camera and microscope were simultaneously used to obtain concrete surface images used as the input data for the ***,training,validation,and testing of the DCNNs were performed based on the DSLR camera and microscope image *** of the analysis indicated that the DCNN employing DSLR image data achieved a relatively higher *** accuracy of the DSLR-derived image data was attributed to the relatively wider range of the DSLR camera,which was beneficial for extracting a larger number of ***,the DSLR camera procured more realistic images than the ***,when the compressive strength of concrete was evaluated using the DCNN employing a DSLR camera,time and cost were reduced,whereas the usefulness ***,an indirect comparison of the accuracy of the DCNN with that of existing non-destructive methods for evaluating the strength of concrete proved the reliability of DCNN-derived concrete strength *** addition,it was determined that the DCNN used for concrete strength evaluations in this study can be further expanded to detect and evaluate various deteriorative factors that affect the durability of structures,such as salt damage,carbonation,sulfation,corrosion,and freezing-thawing.

关键词： Deep convolutional neural network(DCNN) non-destructive testing(NDT) concrete compressive strength digital single-lens reflex(DSLR)camera microscope