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Two-dimensional perovskite SrnbO_(2) n with Zr doping for accelerating photoelectrochemical water splitting

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Journal of Materials Science & Technology 2023年第11期142卷 176-184页

作者： Thanh Tam Thi Tran Van-Huy Trinh Jeongsuk seo Department of Chemistry College of Natural SciencesChonnam National University77 Yongbong-roBuk-guGwangju 61186South Korea

The superior ability of perovskite-type SrnbO_(2) n to absorb intensive visible light makes it a potential semiconductor to produce hydrogen and oxygen by photoelectrochemical(PEC)water splitting under *** surface morphologies,such as shape and structure,of the oxynitride strongly affect its photoactivity,although the mechanism has been hardly ***,we report a two-dimensional(2D)porous SrnbO_(2) n plate with Zr doping,nitrided from layered perovskite Sr_(5)nb_(4)O_(15) and also its largely enhanced PEC water splitting ***^(4+)was doped in Sr_(5)nb_(4)O_(15) during flux-assisted calcination using KCl,producing 2D-type truncated-octahedral Sr_(5)nb_(4)O_(15):Zr plates approximately 50 nm in *** nitridation completely transformed Sr_(5)nb_(4)O_(15):Zr to 2D single-crystalline SrnbO_(2) n:Zr with a large surface area,which was subsequently used to fabricate a thin and uniform photoanode by the spin coating *** a result,the Co(OH)_(x)/SrnbO_(2) n:Zr/FTO photoanode capable of absorbing visible light of up to 680 nm exhibited an activity of 2.0 mA cm^(-2) at 1.23 V vs the reversible hydrogen electrode for water splitting under AM 1.5G simulated *** improvement in photoactivity mainly originated from the 2D surface morphology of SrnbO_(2) n:Zr,which is clearly distinguishable from 3D-type *** to electrochemical analyses,the 2D structure of SrnbO_(2) n:Zr boosted the separation and accelerated the transfer of charges photogenerated during the water splitting,thus driving the reaction ***,the result empirically demonstrates that controlling the surface morphology of SrnbO_(2) n is an effective strategy to suppress the recombination of charges and minimize their diffusion pathway,eventually enhancing the PEC activity.

关键词： Solar water splitting Water oxidation BanbO_(2)n Doping engineering Flux-assisted calcination Spin coating

Investigation of Punch Resistance of the Allomyrira dichtoloma Beetle Forewing

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Journal of Bionic Engineering 2018年第1期15卷 57-68页

作者： ngoc San Ha Vinh Tung Le nam seo Goo Smart Microsystem Research Laboratory Department of Advanced Technology Fusion Division of Interdisciplinary Studies Konkuk University Seou105029 Republic of Korea Faculty of Science Engineering and Technology Swinburne University of Technology Hawthorn VIC 3122 Australia

In this study, the punch resistance of the beetle forewing was investigated to address the ability of the forewing against the external force. The punch resistance of the forewing was measured for different sizes and sexes of beetles using a conventional testing method in conjunction with the Digital Image Correlation （DIC） technique. The results showed that the maximum fracture load was measured around 23 n for the female beetle and around 20.2 n for the male beetle in the front-side punch test. Moreover, the fracture load in the front-side punch test was higher than that in the back-side punch test for both male and female beetles. This means that the beetle forewing plays a protection role against external loads. Furthermore, the puncture energy in the front-side punch test for the female beetle （6.91 m J） was a little higher than that for the male beetle （5.27 mJ）. In addition, the DIC results revealed that the first crack occurred along the trachea line and the second crack then appeared in the direction that was perpendicular to the direction of the first crack. This study provides a com- prehensive understanding of the mechanical protection properties of the beetle forewing and offers a good lesson for studying lightweight bio-inspired composite material.

关键词： beetle forewing punch test punch energy digital image correlation

Full‑Fiber Auxetic‑Interlaced Yarn Sensor for Sign‑Language Translation Glove Assisted by Artificial neural network

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nano-Micro Letters 2022年第8期14卷 269-282页

作者： Ronghui Wu Sangjin seo Liyun Ma Juyeol Bae Taesung Kim Department of Mechanical Engineering Ulsan National Institute of Science and Technology(UNIST)50 UNIST‑GilUlsan 44919Republic of Korea College of Physical Science and Technology Xiamen UniversityXiamen 361005People’s Republic of China

Yarn sensors have shown promising application prospects in wearable electronics owing to their shape adaptability, good flexibility, and weavability. However, it is still a critical challenge to develop simultaneously structure stable, fast response, body conformal, mechanical robust yarn sensor using full microfibers in an industrial-scalable manner. Herein, a full-fiber auxetic-interlaced yarn sensor(AIYS) with negative Poisson’s ratio is designed and fabricated using a continuous, mass-producible, structure-programmable, and low-cost spinning technology. Based on the unique microfiber interlaced architecture, AIYS simultaneously achieves a Poisson’s ratio of-1.5, a robust mechanical property(0.6 c n/dtex), and a fast train-resistance responsiveness(0.025 s), which enhances conformality with the human body and quickly transduce human joint bending and/or stretching into electrical signals. Moreover, AIYS shows good flexibility, washability, weavability, and high repeatability. Furtherly, with the AIYS array, an ultrafast full-letter sign-language translation glove is developed using artificial neural network. The sign-language translation glove achieves an accuracy of 99.8% for all letters of the English alphabet within a short time of 0.25 s. Furthermore, owing to excellent full letter-recognition ability, real-time translation of daily dialogues and complex sentences is also demonstrated. The smart glove exhibits a remarkable potential in eliminating the communication barriers between signers and non-signers.

关键词： negative Poisson’s ratio yarns Interlaced yarn sensors Smart glove Deep learning Sign-language translation

new approaches to water purification for resource- constrained settings： Production of activated biochar by chemical activation with diammonium hydrogenphosphate

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Frontiers of Chemical Science and Engineering 2018年第1期12卷 194-208页

作者： Mohit nahata Chang Y. seo Pradeep Krishnakumar Johannes Schwank Department of Chemical Engineering University of Michigan-Ann Arbor Ann Arbor MI 48109 USA

A significant portion of the world＇s population does not have access to safe drinking water. This problem is most acute in remote, resource-constrained rural settings in developing countries. Water filtration using activated carbon is one of the important steps in treating con- taminated water. Lignocellulosic biomass is generally available in abundance in such locations, such as the African rain forests. Our work is focused on developing a simple method to synthesize activated biochar from locally available materials. The preparation of activated biochar with diammonium hydrogenphosphate （DAP） as the activating agent is explored under n2 flow and air. The study, carried out with cellulose as a model biomass, provides some insight into the interaction between DAP and biomass, as well as the char forming mechanism. Various characterization techniques such as n2 physisorption, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy are utilized to compare the properties between biochar formed under nitrogen and partial oxidative conditions. At a temperature of 450 ℃, the loading of DAP over cellulose is systematically varied, and its effect on activation is examined. The activated biochar samples are predominantly microporous in the range of concentrations studied. The interaction of DAP with cellulose is investigated and the nature of bonding of the heteroatoms to the carbonaceous matrix is elucidated. The results indicate that the quality of biochar prepared under partial oxidation condition is comparable to that ofbiochar prepared under nitrogen, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained settings.

关键词： cellulose DAP activation heteroatom,microporous

Impact of UV-A Radiation on Erythemal UV and UV-index Estimation over Korea

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Advances in Atmospheric Sciences 2015年第12期32卷 1639-1646页

作者： Sang seo PARK Yun Gon LEE Jung Hyun KIM Department of Atmospheric Sciences Yonsei University Department of Atmospheric Sciences Chungnam National University

Because total UV （TUV） in the UV-A region is 100 times higher than in the UV-B region, UV-A is a considerable compo- nent when calculating erythemal UV （EUV） and UV-index. The ratio of EUV to TUV in the UV-A value [EUV（A）/TUV（A）] is investigated to convert the EUV（A） from TUV（A） for broadband observation. The representative value of EUV（A）/TUV（A）, from the simulation study, is 6.9 × 10^- 4 changing from 6.1 ×10^-4 to 7.0 × 10^ -4 as aerosol optical depth, total ozone and solar zenith angle change. By adopting the observational data of EUV（B） and TUV（A） from UV-biometer measurements at Yonsei University [（37.57°n, 126.95°E）, 84 m above sea level], the EUV irradiance increases to 15% of EUV（B） due to the consideration of EUV（A） from the data of TUV（A） observation. Compared to the total EUV observed from the Brewer spec- trophotometer at the same site, the EUV（B） from the UV-biometer observes only 95% of total EUV, and its underestimation is caused by neglecting the effect of UV-A. However, the sum of EUV（B） and EUV（A） [EUV（A＋B）] from two UV-biometers is 10% larger than the EUV from the Brewer spectrophotometer because of the spectral overlap effect in the range 320-340 nm. The correction factor for the overlap effect adjusts 8% of total EUV.

关键词： erythemal UV total UV UV-B UV-biometer

Comparisons of three data storage models in parametric temporal databases

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Journal of Central South University 2013年第7期20卷 1919-1927页

作者： seo-Young nOH Shashi K. GADIA Haengjin JAnG Supercomputing Center Korea Institute of Science and Technology Information Department of Computer Science Iowa State University

The parametric temporal data model captures a real world entity in a single tuple, which reduces query language complexity. Such a data model, however, is difficult to be implemented on top of conventional databases because of its unfixed attribute sizes. XML is a matured technology and can be an elegant solution for such challenge. Representing data in XML trigger a question about storage efficiency. The goal of this work is to provide a straightforward answer to such a question. To this end, we compare three different storage models for the parametric temporal data model and show that XML is not worse than any other approaches. Furthermore, XML outperforms the other storages under certain conditions. Therefore, our simulation results provide a positive indication that the myth about XML is not true in the parametric temporal data model.

关键词： data representation parametric data model XML-based representation

Optimal Resource Allocation Method for Device-to-Device Communication in 5G networks

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Computers, Materials & Continua 2022年第4期71卷 1-15页

作者： Fahd n.Al-Wesabi Imran Khan Saleem Latteef Mohammed Huda Farooq Jameel Mohammad Alamgeer Ali M.Al-Sharafi Byung seo Kim Department of Computer Science King Khalid UniversityMuhayel AseerKSA Faculty of Computer and IT Sana’a UniversityYemen Department of Electrical Engineering University of Engineering and TechnologyPeshawarPakistan Department of Medical Instrumentation Techniques Engineering Electrical Engineering Technical CollegeMiddle Technical UniversityBaghdad10013Iraq Department of Information Systems King Khalid UniversityMayahel AseerKSA Department of Computer Science College of Computers and Information TechnologyUniversity of BishaKSA Department of Software and Communications Engineering Hongik UniversityKorea

With the rapid development of the next-generation mobile network,the number of terminal devices and applications is growing ***,how to obtain a higher data rate,wider network coverage and higher resource utilization in the limited spectrum resources has become the common research goal of ***-to-Device(D2D)communication technology and other frontier communication technologies have ***-to-Device communication technology is the technology that devices in proximity can communicate directly in cellular *** has become one of the key technologies of the fifth-generation mobile communications system(5G).D2D communication technology which is introduced into cellular networks can effectively improve spectrum utilization,enhance network coverage,reduce transmission delay and improve system throughput,but it would also bring complicated and various interferences due to reusing cellular resources at the same *** resource management is one of the most challenging and importing issues to give full play to the advantages of D2D *** resource allocation is an important factor that needs to be addressed in D2D ***,this paper proposes an optimization method based on the game-matching *** main idea is to model the optimization problem of the quality-of-experience based on user fairness and solve it through game-matching *** results show that the proposed algorithm effectively improved the resource allocation and utilization as compared with existing algorithms.

关键词： D2D communication resource allocation optimization networks

Phase stability and mechanical properties of wire+arc additively manufactured H13 tool steel at elevated temperatures

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Journal of Materials Science & Technology 2021年第8期67卷 80-94页

作者： A.n.M.Tanvir Md.R.U.A hsan Gijeong seo Brian Bates Chanho Lee Peter K.Liaw Mark noakese Andrzej nycz Changwook Ji Duck Bong Kim Department of Mechanical Engineering Tennessee Technological UniversityCookevilleTN 38505USA Department of Manufacturing and Engineering Technology Tennessee Technological UniversityCookevilleTN 38505USA Center for Manufacturing Research Tennessee Technological UniversityCookevilleTN 38505USA Department of Materials Science and Engineering University of TennesseeKnoxvilleTN 37996USA Manufacturing Demonstration Facility Oak Ridge National LaboratoryOak RidgeTN 37830USA Advanced Forming Process R&D Group Korea Institute of Industrial TechnologyUlsan 44413Republic of Korea

Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near *** offers the benefits of inexpensive initial system setup and a high deposition rate for fabricating medium-and large-sized parts such as die-casting *** this study,AISI H13 tool steel,a popular die-casting tool metal,is manufactured by cold metal transfer(CMT)-based WAAM and is then comprehensively analyzed for its microstructural and mechanical ***-dependent phase combinations are observed,which could be explained by nonequilibrium thermal cycles that resulted from the layer-by-layer stacking mechanism used in *** addition,remelting and reheating of the layers reduces welding anomalies(e.g.,pores and voids).The metallurgical characteristics of the H13 strongly correlate with the mechanical *** combinations of phases at different locations of the additively manufactured part exhibit a periodic microhardness ***,Retained Austenite,Ferrite,and Carbide phases are found in combination at different locations of the part based on the part’s temperature distribution during additive ***,the tensile properties at elevated temperatures(23℃,300℃,and 600℃)are comparable to those from other WAAM and additive manufacturing(AM)*** X-ray diffraction results verify that the microstructural stability of the fabricated parts at high temperatures would allow them to be used in high temperatures.

关键词： Tool steel Martensitic steel Wire+arc additive manufacturing(WAAM) High temperature tensile test High temperature XRD

Reversible and controllable threshold voltage modulation for n-channel MoS2 and p-channel MoTe_(2 )field-effect transistors via multiple counter doping with ODTS/poly-L-lysine charge enhancers

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nano Research 2021年第9期14卷 3214-3227页

作者： Seung Gi seo Jinheon Jeong Seung Yeob Kim Ajit Kumar Sung Hun Jin Department of Electronic Engineering Incheon National UniversityAcademy-ro 119Yeongsu-guIncheon 22012Republic of Korea

Confronted by the inherent physical limitations in scaling down Si technology,transition metal dichalcogenides(TMDCs)as alternatives are being tremendously researched and paid attention ***,mature counter doping technology for TMDCs is still elusive,and thus,a controllable and reversible charge enhancer is adopted for acceptor(or donor)-like doping via octadecyltrichlorosilane(ODTS)(or poly-L-lysine(PLL))***,multiple counter doping for TMDC field-effect transistors(FETs),combined with a threshold voltage(V;h)freezing scheme,renders the V_(th) modulation controllable,with negligible degradation and decent sustainability of FETs even after each treatment of a representative charge *** parallel,the counter doping mechanism is systematically investigated via photoluminescence spectroscopy,X-ray photoelectron spectroscopy,atomic force microscopy(AFM),surface energy characterization,and measurement of optoelectronic properties under illumination with light of various *** impressively,complementary inverters,composed of type-converted molybdenum ditelluride(MoTe_(2)>FETs and hetero-TMDC FETs in enhancement mode,are demonstrated via respective ODTS/PLL ***,driving backplane application for micro-light-emitting diode(p-LED)displays and physical validation of a corresponding counter doping scheme even for flexible polyethylene terephthalate(PET)substrates could be leveraged to relieve daunting challenges in the application of nanoscale Si-based three-dimensional(3D)stacked systems,with potential adoption of ultralow power and monolithic optical interconnection technology.

关键词： transition metal dichalcogenides(TMDCs) counter doping charge enhancer field-effect transistors micro-light-emitting diode(m-LED)