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Enhanced photocatalytic degradation of lindane using metal–semiconductor Zn@ZnO and ZnO/Ag nanostructures

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Journal of Environmental Sciences 2018年第12期30卷 107-115页

作者： Hyeon Jin Jung Ravindranadh Koutavarapu seulki Lee Ju Hyun Kim Hyun Chul choi Myong Yong choi Department of Chemistry (BK21+) and Research Institute of Natural Science Gyeongsang National University Department of Chemistry Chonnam National University

To achieve enhanced photocatalytic activity for the degradation of lindane, we prepared metal–semiconductor composite nanoparticles（NPs）. Zn@ZnO core–shell（CS） nanocomposites, calcined ZnO, and Ag-doped ZnO（ZnO/Ag） nanostructures were prepared using pulsed laser ablation in liquid, calcination, and photodeposition methods, respectively, without using surfactants or catalysts. The as-prepared catalysts were characterized by using X-ray diffraction（XRD）, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, ultraviolet–visible（UV–vis） spectroscopy, and photoluminescence spectroscopy. In addition, elemental analysis was performed by energy dispersive X-ray spectroscopy. The obtained XRD and morphology results indicated good dispersion of Zn and Ag NPs on the surface of the ZnO nanostructures. Investigation of the photocatalytic degradation of lindane under UV–vis irradiation showed that Zn@ZnO CS nanocomposites exhibit higher photocatalytic activity than the other prepared samples. The maximum degradation rate of lindane was 99.5% in 40 min using Zn@ZnO CS nanocomposites. The radical trapping experiments verified that the hydroxyl radical（·OH） was the main reactive species for the degradation of lindane.

关键词： Zn@ZnO ZnO/Ag Lindane Pulsed laser ablation in liquid Photocatalysis

Compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni bulk metallic glasses

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 318-322页

作者： Jihye An Hyunjune Yim choi-Yim Haein Department of Physics Sookmyung Women's University Department of Mechanical & System Design Engineering Hongik University

Starting from the quaternary Cu47Ti34Zr11Ni8 alloy, the compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni alloys was systematically investigated. Quaternary Cu-Ti-Zr-Ni alloys can be cast directly from the melt into copper molds to form fully amorphous strips or rods with the thickness of 3-6 mm. The evidence of the amorphous nature of the cast rods was provided by X-ray spectra. The measured glass transition temperature （Tg） and crystallization temperature （Tx） were obtained for the alloys using differential scanning calorimetry （DSC） at the heating rate of 20 K/s. In the results, the differences between the glass temperature and the crystallization temperature （△Tx=Tx-Tg） are measured with values ranging up to 33-55 K. The reduced glass transition temperature （Trg）, which is the ratio of the glass temperature to the liquidus temperature （T3, is often used as an indication of the glass-forming ability of metallic alloys. For the present Cu-Ti-Zr-Ni alloys, this ratio is typically in the range of 0.5838-0.5959, characteristic of metallic alloys with good glass-forming ability. The elastic constants for several selected alloys were measured using ultrasonic methods. The values of the elastic shear modulus, bulk modulus, and Poisson＇s ratio were also given.

关键词： bulk metallic glasses (BMGs) quatemary alloys elastic constants glass-forming ability

Reaction mechanism and additional lithium storage of mesoporous MnO_(2) anode in Li batteries

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Journal of Energy Chemistry 2021年第2期30卷 276-284,I0010页

作者： Jaesang Yoon Woosung choi Taewhan Kim Hyunwoo Kim Yun seok choi Ji Man Kim Won-Sub Yoon Department of Energy Science Sungkyunkwan UniversitySuwon 16419South Korea Department of Chemistry Sungkyunkwan UniversitySuwon 16419South Korea

Nanostructured transition metal oxides,employed as anode materials for lithium-ion batteries,exhibit a higher capacity than the theoretical capacity based on the conversion *** date,the reasons behind this phenomenon are *** the one-step evolution of anode material for lithium-ion batteries,it is essential to understand the lithium storage reaction mechanism of the anode ***,we provide a detailed report on the lithium storage and release mechanism of MnO2,using synchrotron-based X-ray techniques.X-ray diffraction and X-ray absorption spectroscopy results indicate that during the first discharge,MnO2 is reduced in the order of MnO2→LixMnO2(1

关键词： Mesoporous MnO_(2) Reaction mechanism Electrolyte-derived surface layer Synchrotron-based X-ray techniques Anode Li battery

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

Numerical analysis of thermal plasma scrubber for CF4 decomposition

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Plasma Science and Technology 2019年第6期21卷 9-14页

作者： J KO T H KIM S choi Department of Nuclear and Energy Engineering Jeju National University Jeju 63243 Republic of Korea Institute for Nuclear Science and Technology Jeju National University Jeju 63243 Republic of Korea

CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse *** must be removed or converted safely due to its extreme *** a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is *** this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition *** decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium *** chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical *** injection position and angle of the CF4 were controlled in order to enhance the decomposition *** vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma *** addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped *** a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.

关键词： numerical simulation decomposition CF4 thermal plasma scrubber

Evaluation of anti-tubercular activity of linolenic acid and conjugatedlinoleic acid as effective inhibitors against Mycobacterium tuberculosis

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Asian Pacific Journal of Tropical Medicine 2016年第2期9卷 121-125页

作者： Won Hyung choi Department of Biomedical Science and Department of Medical Zoology Kyung Hee University School of Medicine

Objective: To evaluate a new pharmacological activity/effect of linolenic acid(α- and γ-form) and conjugated-linoleic acid(CLA) causing antibacterial activity against Mycobacterium tuberculosis(Mtb). Methods: The anti-Mtb activity/effect of linolenic acid and CLA were determined using different anti-Mtb indicator methods such as resazurin microtiter assay(REMA) and MGIT 960 system assay. The Mtb was incubated with various concentrations(12.5–200) μg/m L of the compounds and anti-Mtb first-line drugs for 5 d in the REMA, and for 3 wk in MGIT 960 system assay. Results: Linolenic acid and CLA obviously indicated their anti-Mtb activity/effect by strongly inhibiting the growth/proliferation of Mtb in a dosedependent manner in the REMA and the MGIT 960 system assay. Interestingly, linolenic acid and CLA consistently induced anti-Mtb activity/effect by effectively inhibiting the growth/proliferation of Mtb in MGIT 960 system for 21 d with a single-treatment, and their minimum inhibitory concentrations were measured as 200 μg/m L respectively. Conclusions: These results demonstrate that linolenic acid and CLA not only have effective anti-Mtb activity/properties, but also induce the selective-anti-Mtb effects by strongly inhibiting and blocking the growth/proliferation of Mtb through a new pharmacological activity/action. Therefore, this study provides novel perspectives for the effective use of them and the potential that can be used as potent anti-Mtb candidate drugs, as well as suggests the advantage of reducing the cost and/or time for developing a new/substantive drug by effectively repurposing the existing drugs or compounds as one of new strategies for the global challenge of tuberculosis.

关键词： MGIT 960 system Tuberculosis Drug susceptibility testing γ-linolenic acid

An Approach to Share Architectural Drawing Information and Document Information for Automated Code Checking System

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Tsinghua Science and Technology 2008年第S1期13卷 171-178页

作者： Jungsik choi Inhan Kim Department of Architectural Engineering Kyung-Hee University College of Architecture and Civil Engineering Kyung-Hee University

The purpose of this study is to suggest a way of optimized managing and sharing information between standard architectural drawings and construction documents in Korea architectural industry for automated code checking system by linked STEP and XML. To archive this purpose, the authors have analyzed current research and technical development for STEP and XML link and developed a prototype system for sharing information between model based drawings and XML based construction documents. Finally, the authors have suggested practical use scenario of sharing information through linked STEP and XML using test case of automatic code checking. In the paper, the possibility of constructing integrated architectural computing environment through exchange and sharing of drawing information and external data for the whole building life-cycle, from the conceptual design stage to the construction and maintenance stage has been examined. Automated code checking through linked STEP and XML could be enhanced through col-laboration business, more completed code, improved building performance, and reduced construction costs.

关键词： STEP XML sharing and exchange architectural drawing information construction document information

Prediction accuracy of reservoir break flood simulation model using finite volume method and UAV

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International Journal of Agricultural and Biological Engineering 2020年第6期13卷 7-15页

作者： Jeongbae Jeon Won choi Spatial Information Research Institute Korea Land and Geospatial Infomatix CorporationKorea Land and Geospatial Infomatix CorporationJeollabuk-doSouth Korea Department of Rural Systems Engineering Global Smart Farm Convergence MajorResearch Institute of Agriculture and Life SciencesSeoul National UniversitySeoul 08826South Korea

Methods for producing high-resolution digital topographic maps using an unmanned aerial vehicle(UAV),and 3D fluid dynamics simulation to estimate the flooded areas caused by a collapsed reservoir,were proposed in this *** UAV flight path for photographing damaged areas was divided into two sections considering the drone flight time and overlapping range of the images in the x-and *** metadata taken by the drone were transferred into world coordinates by tracking the key features of the photographs of nearby areas using a 3D rotation *** point cloud data with a 3D space were extracted from the registered images,and a digital surface map(DSM)was produced using a point cloud classification geometric mapping *** amend the serious elevation errors caused by natural or artificial obstacles,a kriging interpolation method was used to reproduce the DSM.A transient computational simulation that considers both the complex geometric topology and hydrodynamic energy of flowing water was conducted using FLOW-3D software to deal with an renormalization group(RNG)turbulence *** flooded areas calculated through visual reading using images taken by the UAV were compared with the 3D simulation results for *** flooded areas estimated through the simulation were approximately 18.3%larger than those found by visual *** flows were mainly observed in obstacles or curved areas of the stream,and the differences in the water depth could be further ***,the villagers confirmed that the flooded areas were much greater than what was seen through the visual ***,the combination of UAV surveying and the 3D simulation method based on the RNG turbulence model is recommended to accurately estimate flooded areas,and it will support an administrative policy aimed at minimizing the economic costs of damage caused by future reservoir collapses.

关键词： reservoir failure flooded area finite volume method unmanned aerial vehicle photogrammetric survey digital surface model

Vertically Integrated Electronics: New Opportunities from Emerging Materials and Devices

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Nano-Micro Letters 2022年第12期14卷 195-223页

作者： seongjae Kim Juhyung seo Junhwan choi Hocheon Yoo Department of Electronic Engineering Gachon University1342 Seongnam-daeroSujeong-guSeongnamGyeonggi-do 13120Republic of Korea Center of Bio-Integrated Electronics Northwestern UniversityEvanstonIL 60208USA Querrey Simpson Institute for Bioelectronics Northwestern UniversityEvanstonIL 60208USA Present Address:Department of Chemical Engineering Dankook University152 Jukjeon-roSuji-guYonginGyeonggi-do 16890Republic of Korea

Vertical three-dimensional(3D)integration is a highly attractive strategy to integrate a large number of transistor devices per unit *** approach has emerged to accommodate the higher demand of data processing capability and to circumvent the scaling limitation.A huge number of research efforts have been attempted to demonstrate vertically stacked electronics in the last two *** this review,we revisit materials and devices for the vertically integrated electronics with an emphasis on the emerging semiconductor materials that can be processable by bottom-up fabrication methods,which are suitable for future flexible and wearable *** vertically stacked integrated circuits are reviewed based on the semiconductor materials:organic semiconductors,carbon nanotubes,metal oxide semiconductors,and atomically thin two-dimensional materials including transi-tion metal *** features,device performance,and fabrication methods for 3D integration of the transistor based on each semiconductor are ***,we highlight recent advances that can be important milestones in the vertically integrated elec-tronics including advanced integrated circuits,sensors,and display *** are remaining challenges to overcome;however,we believe that the vertical 3D integration based on emerging semiconductor materials and devices can be a promising strategy for future electronics.

关键词： Vertical stacking Three-dimensional integration Metal routing Via-hole Two-dimensional semiconductors