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Synthesis of crystalline g-C_(3)N_(4) with rock/molten salts for efficient photocatalysis and piezocatalysis

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Green Energy & Environment 2024年第5期9卷 890-898页

作者： Tingting Xu Jung Hur Ping Niu Shulan Wang sangwook lee Sang-Eun Chun Li Li Department of Chemistry College of ScienceNortheastern UniversityShenyang110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China School of Metallurgy Northeastern UniversityShenyang110819China School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea School of Industrial Technology Advances Kyungpook National UniversityDaegu41566Republic of Korea

Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics signiﬁcantly restricts its practical ***,synthesizing highly crystalline g-C_(3)N_(4) with sufﬁcient surface activities still remains ***,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed *** rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for ***,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt *** catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.

关键词： High crystallinity Carbon nitride Photocatalysis Piezocatalysis Overall water splitting

High-performance self-powered color filter-free blue photodetector based on wide-bandgap halide perovskites

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Journal of Materials Science & Technology 2023年第21期152卷 100-108页

作者： Yeonghun Yun Hanbyeol Cho Jina Jung Sung Woong Yang Devthade Vidyasagar Rajendra Kumar Gunasekaran sangwook lee School of Materials Science and Engineering Kyungpook National University(KNU)Daegu 41566South Korea KNU Advanced Material Research Institute Kyungpook National UniversityDaegu 41566South Korea Institute of Microstructure Technology&Light Technology Institute Karlsruhe Institute of TechnologyKarlsruhe 76131Federal Republic of Germany

Blue photodetectors(PDs)are attracting great attention for various *** blue PDs based on inorganic GaP or InGaN absorbers are limited by their expensive,complex,and high-temperature fabrication *** absorber-based blue PDs still have much lower photode-tecting properties than inorganic blue *** this study,a high-performance self-powered blue PD is developed using methylammonium lead halide(MAPbX_(3);X=I,Br,and Cl)perovskites based on the eco-nomic and facile solution process at low *** composition is obtained through halide-composition *** best-performing device exhibits an average external quantum efficiency and an average detectivity of 42.7%and 8.65×10^(11) Jones,respectively,within the blue *** peak responsivity of the proposed PD is 0.174 A W^(−1) at 455 nm,which is comparable to that of commercial gallium phosphide blue PD(0.180 A W^(−1) at 470 nm).Moreover,the proposed device exhibits excellent environmental stability under ambient air *** findings will act as a basis for next-generation image sensor technologies,such as vertically stacked red/green/blue PDs.

关键词： Perovskites Photodetectors Blue Composition engineering Self-powered Wide bandgap

Digital Image Processing Methods for Bridge Coating Management and Their Limitations

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Journal of Civil Engineering and Architecture 2011年第1期5卷 39-47页

作者： sangwook lee Department of Construction Engineering and Engineering Technology Texas Tech University Lubbock TX 79424 USA

Accurate and objective rust defect assessment is required to maintain good quality steel bridge coating surfaces and make a decision whether a bridge shall completely or partially be repainted. For more objective rust defect recognition, digital image recognition methods have been developed for the past few years and they are expected to replace or complement conventional painting inspection methods. Efficient image processing methods are also essential for the successful implementation of steel bridge coating warranty contracting where the owner, usually a state agency, and the contractor inspect steel bridge coating conditions regularly and decide whether additional maintenance actions are needed based on the processed data. There are two approaches to develop automated rust defect recognition methods： applying a statistical method or an artificial intelligence technique. This paper presents the application of previously developed image processing methods for defect evaluations on a bridge coating surface and discusses their limitations under three environmental conditions which are often encountered while acquiring digital images.

关键词： Bridges deterioration image processing condition assessment.

High-throughput compositional mapping of triple-cation tin-lead perovskites for high-efficiency solar cells

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InfoMat 2023年第4期5卷 25-38页

作者： Rajendra Kumar Gunasekaran Jina Jung Sung Woong Yang Jungchul Yun Yeonghun Yun Devthade Vidyasagar Won Chang Choi Chang-Lyoul lee Jun Hong Noh Dong Hoe Kim sangwook lee School of Materials Science and Engineering Kyungpook National UniversityDaeguRepublic of Korea Advanced Photonics Research Institute(APRI) Gwangju Institute of Science and Technology(GIST)GwangjuRepublic of Korea School of Civil Environmental and Architectural EngineeringGreen SchoolKorea UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Korea UniversitySeoulRepublic of Korea

Mixed tin-ead perovskites suffer from structural instability and rapid tin oxidation;thus,the investigation of their optimal composition ranges is important to address these inherent *** critical role of triple cations in mixed Sn–Pb iodides is studied by performing a wide range of compositional screenings over mechanochemically synthesized bulk and solution-processed thin films.A ternary phase map of FA(Sn_(0.6)Pb_(0.4))I_(3),MA(Sn_(0.6)Pb_(0.4))I_(3),and Cs(Sn_(0.6)Pb_(0.4))I_(3)is formed,and a promising composition window of(FA_(0.6-x)MA_(0.4)Cs_(x))Sn_(0.6)Pb_(0.4)I_(3)(0≤x≤0.1)is demonstrated through phase,photoluminescence,and stability *** cell performance and chemical stability across the targeted compositional space are investigated,and FA_(0.55)MA_(0.4)Cs_(0.05)Sn_(0.6)Pb_(0.4)I_(3)with strain-relaxed lattices,reduced defect densities,and improved oxidation stability is *** inverted perovskite solar cells with the optimal composition demonstrate a power conversion efficiency of over 22%with an open-circuit voltage of 0.867 V,which corresponds to voltage loss of 0.363 V,promising for the development of narrow-bandgap perovskite solar cells.

关键词： compositional engineering mixed tin-ead iodides narrow-bandgap perovskites perovskite solar cells strain relaxation ternary phase mapping

Large Eddy Simulation of Pseudo-Shock Waves Using Wall Model

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Open Journal of Fluid Dynamics 2014年第3期4卷 321-333页

作者： sangwook lee Yousuke Ogino Keisuke Sawada Department of Aerospace Engineering Tohoku University Sendai Japan

A supersonic turbulent flowfield involving the pseudo-shock waves in an isolator of a supersonic combustion ramjet is computed using two different LES codes which are a high-order upwind finite volume scheme, and a sixth order compact differencing scheme utilizing the localized artificial diffusivity method for stabilizing shock waves and employing a wall model to enable the use of coarse mesh. In the validation study where a supersonic turbulent boundary layer flow over a flat plate is examined, both LES codes are well validated using velocity profile in the boundary layer given by the hot-wire anemometry and normal stress given by the laser Doppler anemometry. In particular, the sixth order compact differencing scheme gives closer agreements with these experimental data. Then, the validated LES codes are applied to solve the Mach number 2.5 supersonic turbulent flowfield involving the pseudo-shock waves. It is shown that typical features of unsteady flowfield of the pseudo-shock waves are well obtained by both schemes. Again, it is indicated that the sixth order compact differencing scheme gives closer agreements with the existing velocity data obtained by particle image velocimetry and pressure fluctuation data on the wall surface. Besides, the computational cost of the compact differencing scheme is found to be 1/7 of that for the upwind finite volume scheme, even though a wall model is solved at each grid point on the wall surface. Therefore, the obtained results in the present study allow recommending the sixth order compact differencing scheme with a wall model for simulating supersonic turbulent flowfield in an isolator involving the pseudo-shock waves.

关键词： Large Eddy Simulation Wall Model Pseudo-Shock Wave

Surface-functionalized hole-selective monolayer for high efficiency single-junction wide-bandgap and monolithic tandem perovskite solar cells

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Journal of Energy Chemistry 2024年第1期88卷 317-326,I0008页

作者： Devthade Vidyasagar Yeonghun Yun Jae Yu Cho Hyemin lee Kyung Won Kim Yong Tae Kim Sung Woong Yang Jina Jung Won Chang Choi Seonu Kim Rajendra Kumar Gunasekaran Seok Beom Kang Kwang Heo Dong Hoe Kim Jaeyeong Heo sangwook lee School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Materials Science and Engineering and Optoelectronics Convergence Research CenterChonnam National UniversityGwangju 61186Republic of Korea Department of Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea

Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transferdynamics of perovskite solar cells(PSCs).Herein,we report a facile but powerful method to functionalize the surface of 2PACz-SAM,by which reproducible,highly stable,high-efficiency wide-bandgap PSCs can be *** 2PACz surface treatment with various donor number solvents improves assembly of 2PACz-SAM and leave residual surface-bound solvent molecules on 2PACz-SAM,which increases perovskite grain size,retards halide segregation,and accelerates hole *** surface functionalization achieves a high power conversion efficiency(PCE)of 17.62%for a single-junction wide-bandgap(~1.77 e V)*** also demonstrate a monolithic all-perovskite tandem solar cell using surfaceengineered HSC,showing high PCE of 24.66%with large open-circuit voltage of 2.008 V and high fillfactor of 81.45%.Our results suggest this simple approach can further improve the tandem device,when coupled with a high-performance narrow-bandgap sub-cell.

关键词： Perovskite solar cells 2PACz Monolithic tandem solar cells Wide bandgap

An ultralong-life SnS-based anode through phosphate-induced structural regulation for high-performance sodium ion batteries

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Science Bulletin 2022年第20期67卷 2085-2095,M0004页

作者： Ying Wang Hongguan Li Silin Chen Boyin Zhai Shuanlong Di Guangying Gao sangwook lee Sangeun Chun Shulan Wang Li Li School of Metallurgy Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Department of Chemistry College of ScienceNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea School of Industrial Technology Advances Kyungpook National UniversityDaegu 41566Republic of Korea

As a star representative of transition metal sulfides, Sn S is viewed as a promising anode-material candidate for sodium ion batteries due to its high theoretical capacity and unique layered structure. However,the extremely poor electrical conductivity and severe volume expansion strongly hinder its practical application while achieving a high reversible capacity with long-cyclic stability still remains a grand challenge. Herein, different from the conventional enhancement method of elemental doping, we report a rational strategy to introduce PO_(4)^(3-)into the Sn S layers using phytic acid as the special phosphorus ***, the presence of PO_(4)^(3-)in the form of Sn–O–P covalent bonds can act as a conductive pillar to buffer the volume expansion of Sn S while expanding its interlay spacing to allow more Na+storage, supported by both experimental and theoretical evidences. Profiting from this effect combined with microstructural metrics by loading on high pyridine N-doped reduced graphene oxide, the as-prepared material presented an unprecedented ultra-long cyclic stability even after 10,000 cycles along with high reversible capacity and excellent full-cell performances. The findings herein open up new opportunities for elevating electrochemical performances of metal sulfides and provide inspirations for the fabrication of advanced electrode materials for broad energy use.

关键词： SnS Phytic acid Sodium ion batteries Ultra-long cyclic stability Anode

Combustion and emission characteristics of a dual injection system applied to a DISI engine

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Petroleum Science 2014年第3期11卷 424-431页

作者： Byungdeok In sangwook Park Hyungmin Kim Kihyung lee Hanyang University

Concerns about environmental pollution and energy shortages have increased worldwide. One approach to reduce CO2 emissions from gasoline engines is to achieve stratified charge combustion with various injection ratios using port fuel injection （PFI） and direct injection. The combustion and emission characteristics of a 4-valve direct injection spark ignition （DISI） engine equipped with a dual injection system were investigated while the injection ratio was varied. When the direct injection ratio increased, the lean limit A/F was extended. This suggests that the dual injection gasoline engine with both PFI and direct injection can meet severe vehicle emission and fuel economy requirements. The dual injection system had higher combustion pressure than that of either a conventional or direct injection systems. Therefore, the engine power of a dual injection DISI engine would be higher than that of a single injection DISI engine. However, NOx emissions increased compared with the emission levels in both PFI and DISI systems.

关键词： Direct injection spark ignition (DISI) injection ratio lean burn combustion stratified combustion lean limit A/F

Development of Cloud Based Air Pollution Information System Using Visualization

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Computers, Materials & Continua 2019年第6期59卷 697-711页

作者： sangwook Han JungYeon Seo Dae-Young Kim SeokHoon Kim HwaMin lee Deptartment of Computer Science and Engineering Soonchungyang UniversityAsan31538Korea School of Information Technology Engineering Daegu Catholic UniversityGyeongsan38430Korea Department of Computer Software and Engineering Soonchungyang UniversityAsan31538Korea

Air pollution caused by fine dust is a big problem all over the world and fine dust has a fatal impact on human *** there are too few fine dust measuring stations and the installation cost of fine dust measuring station is very *** this paper,we propose Cloud-based air pollution information system using *** measure fine dust,we have developed an inexpensive measuring device and studied the technique to accurately measure the concentration of fine dust at the user’s *** we have developed the smartphone application to provide air pollution *** our system,we provide collected data based analytical results through effective data *** system provides information on fine dust value and action tips through the air pollution information *** it supports visualization on the map using the statistical program *** user can check the fine dust statistics map and cope with fine dust accordingly.

关键词： Air pollution visualization R big data cloud clusters