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The Gas-to-Dust Relation in the Dark Cloud L1523-Observational Evidence for CO Gas Depletion

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Chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 686-692页

作者： H.G.kim b.G.kim J.H.Jung korea Astronomy and Space Science Institute 61-1 Hwaam Yuseong Daejeon 305-348 Korea

Correlation between gas and dust column density has been studied for the dark globule L1523. The 13CO（J=1→0） emission is used for tracing the gas, and the IR emissions, for tracing the dust constituent. In order to match the beam resolution between the images, a beam de-convolution algorithm based on the Maximum Correlation Method （MCM） was applied on the Infrared Astronomical Satellite （IRAS） data. The morphology of 13CO column density map shows a close correlation to that of 100μm dust optical depth. The distribution of the optical depth at 100 μm follows that of gas column density more closely than does the flux map at either 60 or 100μm. The ratio of the 13CO column density to the 100μm optical depth shows a decreasing trend with increasing dust optical depth in the central part, indicating possible molecular gas condensation onto dust particles. The excessive decrease in the CO column density in the envelope may most probably be due to the photo-dissociation of CO molecules.

关键词： ISM: clouds ISM: dust ISM: molecules

broadband electroluminescence from reverse breakdown in individual suspended carbon nanotube pn-junctions

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Nano Research 2020年第10期13卷 2857-2861页

作者： bo Wang Sisi Yang Yu Wang Younghee kim Ragib Ahsan Rehan k.apadia Stephen kDoorn Han Htoon Stephen b.Cronin Department of Physics and Astronormy University of Southern CalforniaLos AngelesCA 90089USA Ming Hsieh Department of Electrical Engineering University of Southern CaliforniaLos AngelesCA 90089USA Mork Farmily Department of Chemical Engineering and Materials Science University of Southern CaliforniaLos AngelesCA 90089USA Center for Integrated Nanotechnologies Materials Physics and Applications DivisionLos Alamos National LaboratoryLos AlamosNM 87545USA

There are various mechanisms of light emission in carbon nanotubes (CNTs), which give rise to a wide range of spectral emission characteristics that provide important information regarding the underlying physical processes that lead to photon emission. Here, we report spectra obtained from individual suspended CNT dual-gate field effect transistor (FET) devices under different gate and bias conditions. by applying opposite voltages to the gate electrodes (i.e., Vg1 = –Vg2), we are able to create a pn-junction within the suspended region of the CNT. Under forward bias conditions, the spectra exhibit a peak corresponding to E11 exciton emission via thermal (i.e., blackbody) emission occurring at electrical powers around 8 μW, which corresponds to a power density of approximately 0.5 MW/cm2. On the other hand, the spectra observed under reverse bias correspond to impact ionization and avalanche emission, which occurs at electrical powers of ~ 10 nW and exhibits a featureless flat spectrum extending from 1,600 nm to shorter wavelengths up to 600 nm. Here, the hot electrons generated by the high electric fields (~ 0.5 MV/cm) are able to produce high energy photons far above the E11 (ground state) energy. It is somewhat surprising that these devices do not exhibit light emission by the annihilation of electrons and holes under forward bias, as in a light emitting diode (LED). Possible reasons for this are discussed, including Auger recombination.

关键词： ballistic avalanche high-field band-to-band photoemission

Zeolitic imidazolate framework-67 derived Al-Co-S hierarchical sheets bridged by nitrogen-doped graphene:Incorporation of PANI derived carbon nanorods for solid-state asymmetric supercapacitors

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Journal of Energy Chemistry 2022年第11期31卷 429-445,I0012页

作者： Emad S.Goda bidhan Pandit Sang Eun Hong bal Sydulu Singu Seong k.kim Essam b.Moustafa kuk Ro Yoon kuk Ro Yoon Organic Nanomaterials Lab Department of ChemistryHannam UniversityDaejeon 34054Republic of Korea Gas Analysis and Fire Safety Laboratory Chemistry DivisionNational Institute for Standards136Giza 12211Egypt Department of Materials Science and Engineering and Chemical Engineering Universidad Carlos Ⅲ de MadridAvenida de La Universidad 3028911 LeganésMadridSpain Department of Chemical and biomolecular Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Chemical Engineering Hannam University1646 Yuseongdae-roYuseong-guDaejeon 34054Republic of Korea Mechanical Engineering Department Faculty of EngineeringKing Abdulaziz UniversityP.O.Box 80204Jeddah 22254Saudi Arabia

Metal sulfides have been widely enticed as battery-type electrodes in supercapacitor devices because of their maximal theoretical ***,their lower conductivity and ion transport kinetics can largely restrict their rate performance,hence the practical usage in fields of demanding high power ***,the design of new electrodes with higher energy and power densities remains a highly challenging *** the best of our knowledge,a novel hierarchical composite of Al-CoS_(2) on nitrogendoped graphene(NG)is prepared based on a zeolite imidazole framework using a simple and scalable hydrothermal *** this hybrid,ultrathin Al-CoS_(2) nanosheet arrays are vertically orientated on the NG framework to limit self-aggregation,hence increasing the electrical property and cycle stability of *** is investigated that the Al/Co feeding ratio plays a crucial role in controlling the obtained hierarchical structure of Al-Co-S sheets and their electrode ***,Al^(3+) can influence remarkably the morphology and electrochemical property of the resultant graphene *** effective synergism is noticed between the redox Al-CoS_(2) and NG resulting in fast electron transfer and chargingdischarging ***,when the as-developed composite is utilized as a positive electrode at an applied current density of 1 A/g,a specific capacitance of 1915.8 F/g is attained with ultra-long cycle stability(96%,10,000 cycles)and an excellent retention rate(~89%).As a consequence,when a solid-state asymmetric supercapacitor(ASC)device is made by combining an Al-CoS_(2) @NG hybrid with a negative electrode made of polyaniline(PANI)derived carbon nanorods(PCNRs),it demonstrates remarkable specific capacitance(188 F/g),energy density(66.9 Wh/kg),and cyclic stability of 92%after 10,000 *** may open the pathway for the application of the next-generation supercapacitors in the future.

关键词： Hierarchical sheets MOFs Al-doped CoS_(2) Nitrogen-doped graphene Solid-state supercapacitor

Tribology of WC reinforced SiC ceramics: Influence of counterbody

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Friction 2019年第2期7卷 129-142页

作者： Sandan kumar SHARMA b.Venkata MANOJ kUMAR Young-Wook kim Department of Metallurgical and Materials Engineering Indian Institute of Technology (IIT) Roorkee TriboCeramics Laboratory Department of Materials Science and Engineeringthe University of Seoul

Hot pressed silicon carbide(SiC) composites prepared with 0, 10, 30 or 50 wt% tungsten carbide(WC) are subjected to dry sliding wear against WC-Co and steel ball. In particular an attempt has been made to answer the following important questions:(i) How does the load(from 5 to 20 N) effect sliding wear behaviour of SiC-ceramics against WC-Co and steel counterbodies?(ii) Is there any effect of WC content on friction and wear characteristics of SiC ceramics?(iii) Does the dominant material removal mechanism of SiC ceramics change with the addition of WC or counterbody?(iv) What is the influence of mechanical properties on the sliding wear? Experimental results indicated that coefficient of friction(COF) for the SiC ceramics varied between 0.66 and 0.33 with change in load and counterbodies. Wear volume for SiC ceramics found approximately 6-10 times more against WC-Co as compared against steel. Wear volume changes from 2.0 × 10^(–3)mm^3 to 1.2 × 10^(–2)mm^3 with change in counterbodies for SiC -(10, 30 or 50 wt%) WC composite at 20 N. SiC ceramics indicated abrasion and composites reveal tribochemical wear as major material removal mechanisms. Wear is influenced by the hardness of counterbody and fracture toughness of SiC -WC composites.

关键词： silicon carbide tungsten carbide composites steel sliding wear counterbody

Electronic fingerprint mechanism of NO_(x) sensor based on single-material SnP_(3) logical junction

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npj Computational Materials 2022年第1期8卷 2107-2116页

作者： Muhammad S.Ramzan Agnieszka b.kuc Han Seul kim Department of Physics and Earth Sciences Jacobs University BremenCampus Ring 128759BremenGermany Institut für Physik Carl von Ossietzky Universität Oldenburg26129OldenburgGermany Helmholtz-Zentrum Dresden-Rossendorf Abteilung RessourcenökologieForschungsstelle LeipzigPermoserstr.1504318LeipzigGermany Division of National Supercomputing R&D Korea Institute of Science and Technology Information(KISTI)245 Daehak-roYuseong-guDaejeon34141Republic of Korea

An extraordinary sensing ability of the SnP3-based single-material logical junction for harmful NO_(x)gases was explored in the present work through a set of first-principles electronic structure *** a sensing platform,a metal-semiconductor-metal lateral junction composed of a single material was designed based on the metallic/semiconducting characteristics of trilayer/monolayer SnP_(3).Lacking a Schottky barrier at the electrode-channel interface,the gas-specific charge transfer between the SnP_(3) layer and gas molecules was precisely detected based on the current-voltage ***_(x)gases with strong adsorption strength and charge transfer amount on the SnP_(3)substrate were shown to be particularly well detected in this manner,in terms of either the absolute magnitude of the current or negative differential resistance(NDR)at a reasonably small bias voltage as a sensing *** work will provide a new pathway to design a Schottky barrier-free metal-semiconductor junction for highly sensitive sensor applications.

关键词： gases barrier charge

High Coercive NdFeb Thin Film Obtained by Diffusion Annealing

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Journal of Materials Science & Technology 2000年第2期16卷 111-112页

作者： MJ.kim and Y.b.kim (korea Research Institute of Standards and Science, Taejon 305-600, korea) C.b.Song (kongju National University, kongju 314-701, Chungnam, korea) Y.Li, D.S.Suhr, C.O.kim and T.k.kim (Chungnam National University, Taejon 305-340, korea) korea Research Institute of Standards and Science Taejon 305-600 South Korea kongju National University Kongju 314-701 Chungnam South Korea Chungnam National University Taejon 305-340 South Korea

The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeb/Nd/Ta]thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeb layer (R=0～3.3), then diffused and crystallized by annealing at 650℃ for 10 min. The film without Nd layer showed soft magnetic behavior and high content of a-Fe phase. The films with R > =1 showed good hard magnetic properties with the high coercivity of about 20 kOe.

关键词： Thin NdFeb High Coercive NdFeb Thin Film Obtained by Diffusion Annealing

Use of ^(137)Cs and ^(210)Pb_(ex) fallout radionuclides for spatial soil erosion and redistribution assessment on steeply sloping agricultural highlands

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Journal of Mountain Science 2021年第11期18卷 2888-2899页

作者： Jung-Hwan YOON Young-Nam kim kye-Hoon kim M.b.kIRkHAM Hyuck Soo kim Jae E.YANG kangwon Institute of Inclusive Technology Kangwon National UniversityChuncheon 24341Republic of Korea Department of biological Environment Kangwon National UniversityChuncheon 24341Republic of Korea Institute of Agriculture and Life Science Gyeongsang National UniversityJinju 52828Republic of Korea Department of Environmental Horticulture University of SeoulSeoul 02504Republic of Korea Department of Agronomy Kansas State UniversityManhattanKS 66506-0110USA

The steeply sloping agricultural highlands in korea have severe soil *** of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not feasible using existing soil-erosion *** study measured the site-specific concentrations of ^(137)Cs and ^(210)Pb_(ex) on both a highland slope(33%slope)and a reference site(undisturbed flat area)to estimate soil erosion and *** use of the fallout radionuclide(FRN)method was evaluated to see if it is a suitable method for characterizing soil *** were compared with those obtained with the Universal Soil Loss Equation(USLE),which is an empirical model that estimates annual soil *** average concentrations of ^(137)Cs and ^(210)Pb_(ex) at the reference site were 11.57±0.24 bq kg^(-1) and 59.74±4.2 bq kg^(-1),*** of ^(137)Cs and ^(210)Pb_(ex) in the experimental slope were 16.4%and 10.8%,respectively,of those at the reference *** inventories were lower at the upper point of the slope than those at the basal point of the *** of ^(137)Cs and ^(210)Pb_(ex) were significantly correlated with available phosphorus,organic matter,CEC,and exchangeable *** of soil redistribution rate using ^(137)Cs and ^(210)Pb_(ex) showed site-specific variations at different points along the slope,and respective ranges were^(-1)7.46~-207.51 and 1.55~-581.38 Mgha^(-1) yr^(-1),which indicated that more erosion was assessed by ^(210)Pb_(ex) than by ^(137)*** analysis showed that soil erosion occurred along the entire slope,except for the bottom point of the slope where 1.55 Mgha^(-1) yr^(-1) of sediment *** USLE provided a single value of the average annual soil loss in the entire slope,which was either 166 or 398 Mgha^(-1) yr^(-1),depending on the soil erodibility factor(soil series factor and calculated factor from soil sample analysis)used in t

关键词： Soil erosion Steep highland Fallout radionuclide ^(137)Cs ^(210)Pb_(ex) USLE

Clawed Miniature Inchworm Robot Driven by Electromagnetic Oscillatory Actuator

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Journal of bionic Engineering 2015年第4期12卷 519-526页

作者： kyung-min Lee Youngshik kim Jamie k. Paik buhyun Shin korean Intellectual Property Office Gov. Complex-Daejeon Bldg. 4 189 Cheongsa-ro Se-gu Daejeon 302-701 Korea Department of Mechanical Engineering Hanbat National University 125 Dongseodaero Yuseong-gu Daejeon 305-719 Korea The Institute of Mechanical Engineering EPFL STIlGM UPPAIK BM 4118 (B~timent BM) Station 17 Switzerland

In this research we propose a novel inchworm robot, which is composed of an Electromagnetic Oscillatory Actuator （EOA） and claws. The EOA consists of a yoke, a magnet, and a coil. The overall robot size is 12.2 mm x 11 mm x 9 mm （length x height ~ width）. The locomotion of the robot is achieved by different amounts of slips when the robot stretches and contracts its front leg. To realize locomotion, the working conditions were calculated theoretically and the calculated input signal was applied to the robot. The performance of the inchworm robot was evaluated experimentally with varying input voltages and frequencies. A simple op-amps based driving circuit was used to provide a square-wave input. Travel speed, average distance per step of the robot, and moving distance of the leg and body at each step were measured. The maximum travel speed was 36 mm-s-1 at 30 Hz, which validates our simple locomotion strategy experimentally.

关键词： electromagnetic actuator micro mobile robot inchworm crawler locomotion

Applying robust design to study the effects of stratigraphic characteristics on brittle failure and bump potential in a coal mine

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International Journal of Mining Science and Technology 2018年第1期28卷 137-144页

作者： bo-Hyun kim Mark k.Larson Heather E.Lawson Spokane Mining Research Division NIOSH/CDC

bumps and other types of dynamic failure have been a persistent, worldwide problem in the underground coal mining industry, spanning *** example, in just five states in the *** 1983 to 2014,there were 388 reportable *** significant advances in mine design tools and mining practices,these events continue to *** conditions have been associated with bump potential, such as the presence of stiff units in the local *** effect of a stiff sandstone unit on the potential for coal bumps depends on the location of the stiff unit in the stratigraphic column, the relative stiffness and strength of other structural members, and stress concentrations caused by *** study describes the results of a robust design to consider the impact of different lithologic risk factors impacting dynamic failure *** the inherent variability of stratigraphic characteristics in sedimentary formations,such as thickness, engineering material properties, and location, is significant and the number of influential parameters in determining a parametric study is large, it is impractical to consider every simulation case by varying each parameter ***, to save time and honor the statistical distributions of the parameters, it is necessary to develop a robust design to collect sufficient sample data and develop a statistical analysis method to draw accurate conclusions from the collected *** this study,orthogonal arrays, which were developed using the robust design, are used to define the combination of the(a) thickness of a stiff sandstone inserted on the top and bottom of a coal seam in a massive shale mine roof and floor,(b) location of the stiff sandstone inserted on the top and bottom of the coal seam,and(c) material properties of the stiff sandstone and contacts as interfaces using the 3-dimensional numerical model, *** completion of the numerical experiments, statistical and multivariate analysis are performed using

关键词： bumps Robust design FLAC3D Plastic dissipated energy Multiple regression