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MOLECULAR DESIGn OF LIGHT EMITTInG POLYMERS

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Chinese Journal of Polymer Science 2000年第3期18卷 227-237页

作者： J.W.Yu J.K.kim J.MHong Y.C.kim H.n.Cho D.Y.kim C.Y.kim Polymer Materials Laboratory Korea Institute of Science and TechnologyP.O.Box 131CheongryangSeoul 130-650.Korea

Fluorene-based alternating and statistical copolymers were synthesized by employing reaction methods of Wittig,Heck and *** copolymers were classified into three groups with the photoluminescence(PL)emission maxima at420,475 and 500 nm,*** copolymers with two chromophores having PL emission maxima at 420 and475 nm emitted light with the emission maximum at 475 nm on photoexcitation at 365 nm and improved the quantumefficiency by the energy ***,the intramolecular energy transfer was inefficient compared to the intermolecularenergy transfer when the two chromophores were apart from each other in the range of the Forster critical ***-pyridinedivinylene alternating copolymer was synthesized by the Wittig reaction and found to have physical,electronic andelectrochemical properties of the individual units *** double-layered light emitting diode(LED)with the statisticalcopolymer as an emitting layer and the pyridine-containing copolymer as an electron transporting-hole blocking layer,whichwere sandwiched between ITO and Al,displayed a quantum efficiency of 0.1%.

关键词： Light emitting polymers

Vickers and Knoop Micro-hardness Behavior of Coarse-and Ultrafine-grained Titanium

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Journal of Materials Science & Technology 2010年第10期26卷 904-907页

作者： K.P.Sanosh A.Balakrishnan L.Francis T.n.kim Department of Information and Electronic Materials Engineering College of EngineeringPaichai University Laboratoire SIMAP GPM2 Grenoble-INPUJFCNRS 101 Rue de la PhysiqueBP46 38402 Saint Martin d'He' res CedexFrance University of Genova Department of Chemistry and Industrial Chemistry

The present study focuses on the relationship of hardness with grain size for commercially pure titanium （CpTi） and ultra fine grained titanium （UFG-Ti） produced by equal channel angular process （ECAP） of Cp-Ti）.Vickers and Knoop indentations of UFG-Ti at different loads was ～2.5 times harder than those of *** diffraction （XRD） analysis showed peak broadening in UFG-Ti due to reduced grain size and micro-lattice *** electron microscopy （SEM） revealed that ECAP had reduced the grain size of Cp-Ti by ～10 *** statistics showed UFG-Ti with lower dispersion in hardness values compare to Cp-Ti indicating a more uniform microstructure.

关键词： Vickers Knoop Hardness Ultrafine-grained Titanium

Transient analysis of diffusive chemical reactive species for couple stress fluid flow over vertical cylinder

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Applied Mathematics and Mechanics(English Edition) 2013年第8期34卷 985-1000页

作者： H.P.RAnI G.J.REDDY C.n.kim Department of Mathematics National Institute of Technology Department of Mechanical Engineering College of Advanced Technology (Industrial Liaison Research Institute) Kyung Hee University

The unsteady natural convective couple stress fluid flow over a semi-infinite vertical cylinder is analyzed for the homogeneous first-order chemical reaction effect. The couple stress fluid flow model introduces the length dependent effect based on the material constant and dynamic viscosity. Also, it introduces the biharmonic operator in the navier-Stokes equations, which is absent in the case of newtonian fluids. The solution to the time-dependent non-linear and coupled governing equations is carried out with an unconditionally stable Crank-nicolson type of numerical schemes. numerical results for the transient flow variables, the average wall shear stress, the nusselt number, and the Sherwood number are shown graphically for both generative and destructive reactions. The time to reach the temporal maximum increases as the reaction constant K increases. The average values of the wall shear stress and the heat transfer rate decrease as K increases, while increase with the increase in the Sherwood number.

关键词： couple stress fluid chemical reaction natural convection vertical cylinder,finite difference method

Examination of n-T_(9) conditions required by n=50,82,126 waiting points in r-process

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Communications in Theoretical Physics 2021年第10期73卷 147-157页

作者： nguyen Duy Ly nguyen ngoc Duy nguyen kim Uyen Vinh n T Pham Faculty of Fundamental Sciences Vanlang UniversityHo Chi Minh City 700000Vietnam Department of Physics Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Physics Ho Chi Minh City University of EducationHo Chi Minh City 700000Vietnam

We examined the conditions of neutron density(n) and temperature(T9) required for the n = 50, 82,and 126 isotopes to be waiting points(WP) in the r-process. The nuclear mass based on experimental data presented in the AME2020 database(AME and AME ± Δ) and that predicted using FRDM,WS4, DZ10, and KTUY models were employed in our estimations. We found that the conditions required by the n = 50 WP significantly overlap with those required by the n = 82 ones, except for the WS4 model. In addition, the upper(or lower) bounds of the n-T9 conditions based on the models are different from each other due to the deviations in the two-neutron separation *** standard deviations in the nuclear mass of 108 isotopes in the three n = 50, 82, and 126 groups are about rms = 0.192 and 0.434 Me V for the pairs of KTUY-AME and WS4-KTUY models,respectively. We found that these mass uncertainties result in a large discrepancy in the nn-T_(9) conditions, leading to significant differences in the conditions for simultaneously appearing all the three peaks in the r-process abundance. The newly updated FRDM and WS4 calculations can give the overall conditions for the appearance of all the peaks but vice versa for their old versions in a previous study. The change in the final r-process isotopic abundance due to the mass uncertainty is from a few factors to three orders of magnitude. Therefore, accurate nuclear masses of the r-process key nuclei, especially for 76 Fe,81Cu,127Rh,132Cd,192Dy, and 197Tm, are highly recommended to be measured in radioactive-ion beam facilities for a better understanding of the r-process evolution.

关键词： neutron capture r-process nuclear mass isotopic abundance precise mass measurement

The H∞ Robust Stability and Performance Conditions for Uncertain Robot Manipulators

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 270-272页

作者： Geun Il Song Hae Yeon Park Jung Hoon kim the Department of Electrical Engineering Pohang University of Science and Technology (POSTECH) the Department of Electrical Engineering Pohang University of Science and Technology (POSTECH) the Institute for Convergence Research and Education in Advanced Technology Yonsei University

Dear Editor,H∞This letter develops a new framework for the robust stability and performance conditions as well as the relevant controller synthesis with respect to uncertain robot *** often exist model uncertainties between the nominal model and the real robot manipulator and disturbances. Hence, dealing with their effects plays a crucial role in leading to high tracking performances, as discussed in [1]–[5].

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High-performance MoS_(2)/p^(+)-Si heterojunction field-effect transistors by interface modulation

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nano Research 2022年第7期15卷 6500-6506页

作者： Yoonsok kim Taeyoung kim Eun Kyu kim Department of Physics and Research Institute of natural Science Hanyang UniversitySeoul 04763Republic of Korea

Molybdenum disulfide(MoS_(2)),one of transition metal dichalcogenides,is a promising semiconductor material for electronic or optoelectronic devices due to its favorably electronic ***,in metal-oxide semiconductor field-effect transistor(MOSFET)structures using MoS_(2),electrical performances such as mobility and subthreshold swing are suppressed by the interface trap density between the channel and dielectric ***,the electrical stability of such structures is compromised due to interface traps and that can be analyzed such as current hysteresis and transient ***,we demonstrate MoS_(2) heterojunction field-effect transistors(HFET)by applying MoS_(2)/p^(+)-Si heterojunctions and achieve high performance characteristics,including a mobility of 636.19 cm^(2)/(V∙s),a subthreshold swing of 67.4 mV/dec,minimal hysteresis of 0.05 V,and minimized transient ***,the HFET devices with varying the channel length demonstrated degradation of electrical performance with increasing the overlap area of the channel and dielectric *** results regarding MoS_(2)/p^(+)-Si HFETs resulted in the structural optimization of high-performance electronic devices for practical applications.

关键词： molybdenum disulfide(MoS_(2)) transition metal dichalcogenide junction field-effect transistor dielectric layer interface trap

Evaluation of the k-nearest neighbor method for forecasting the influent characteristics of wastewater treatment plant

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Frontiers of Environmental Science & Engineering 2016年第2期10卷 299-310页

作者： Minsoo kim Yejin kim Hyosoo kim Wenhua PIAO Changwon kim Department of Civil and Environmental Engineering Pusan National University Busan 609-735 Republic of Korea Department of Civil and Environmental Engineering Catholic University of Pusan Busan 609-757 Republic of Korea EnvironSoft Co. Ltd. #511 Industry-University Co.Bld. Pusan Nationai University Busan 609-735 Republic of Korea

The k-nearest neighbor （k-nn） method was evaluated to predict the influent flow rate and four water qualities, namely chemical oxygen demand （COD）, suspended solid （SS）, total nitrogen （T-n） and total phosphorus （T-P） at a wastewater treatment plant （WWTP）. The search range and approach for determining the number of nearest neighbors （nns） under dry and wet weather conditions were initially optimized based on the root mean square error （RMSE）. The optimum search range for considering data size was one year. The square root-based （SR） approach was superior to the distance factor-based （DF） approach in determining the appropriate number of nns. However, the results for both approaches varied slightly depending on the water quality and the weather conditions. The influent flow rate was accurately predicted within one standard deviation of measured values. Influent water qualities were well predicted with the mean absolute percentage error （MAPE） under both wet and dry weather conditions. For the seven-day prediction, the difference in predictive accuracy was less than 5% in dry weather conditions and slightly worse in wet weather conditions. Overall, the k-nn method was verified to be useful for predicting WWTP influent characteristics.

关键词： influent wastewater prediction data-drivenmodel k-nearest neighbor method (k-nn)

Grasping Force Estimation by sEMG Signals and Arm Posture: Tensor Decomposition Approach

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Journal of Bionic Engineering 2019年第3期16卷 455-467页

作者： Sanghyun kim Joowan kim Mingon kim Seungyeon kim Jaeheung Park Department of Transdisciplinary Studies Seoul National University Suwon 16229 Korea Advanced Institutes of Convergence Technology Suwon 16229 Korea

Grasping force estimation using surface Electromyography (sEMG) has been actively investigated as it can increase the manipulability and dexterity of prosthetic hands and robotic hands. Most of the current studies in this area only focus on finding the relationship between sEMG signals and the grasping force without considering the arm posture. Therefore, regression models are not suitable to predict grasping force in various arm postures. In this paper, a method to predict the grasping force from sEMG signals and various grasping postures is developed. The proposed algorithm uses a tensor algebra to train a multi-factor model relevant to sEMG signals corresponding to various grasping forces and postures of the wrist and forearm in multiple dimensions. The multi-factor model is then decomposed into four independent factor spaces of the grasping force, sEMG signals, wrist posture, and forearm posture. Moreover, when a participant executes a new posture, new factors for the wrist and forearm are interpolated in the factor spaces. Thus, the grasping force with various postures can be predicted by combining these factors. The effectiveness of the proposed method is verified through experiments with ten healthy subjects, demonstrating the higher performance of proposed grasping force prediction method than the previous algorithm.

关键词： surface Electromyography (sEMG) grasping force force estimation tensor decomposition

Characterization of lattice parameters gradient of Cu(In1-xGax)Se2 absorbing layer in thin-film solar cell by glancing incidence X-ray diffraction technique

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Journal of Materials Science & Technology 2020年第16期47卷 193-201页

作者： Yong-Il kim Ki-Bok kim Miso kim Department of nano Science University of Science and Technology217GajeongYuseongDaejeon34113Republic of Korea Korea Research Institute of Standards and Science 267GajeongYuseongDaejseon34113Republic of Korea

In or Ga gradients in the Cu(In1-xGax)Se2(CIGS)absorbing layer lead to change the lattice parameters of the absorbing layer,giving rise to the bandgap grading in the absorbing layer which is directly associated with the degree of absorbing ability of the CIGS solar *** tried to characterize the depth profile of the lattice parameters of the CIGS absorbing layer using a glancing incidence X-ray diffraction(GIXRD)technique,and then investigate the bandgap grading of the CIGS absorbing *** the glancing incident angle increased from 0.50 to 5.00°,the a and c lattice parameters of the CIGS absorbing layer gradually decreased from 5.7776(3)to 5.6905(2)?,and 11.3917(3)to 11.2114(2)?,*** depth profile of the lattice parameters as a function of the incident angle was consistent with vertical variation in the compositionof In or Ga with depth in the absorbing *** variation of the lattice parameters was due to the difference between the ionic radius of In and Ga co-occupying at the same crystallographic *** to the results of the depth profile of the refined parameters using GIXRD data,the bandgap of the CIGS absorber layer was graded over a range of 1.222-1.532 *** approach allows to determine the In or Ga gradients in the CIGS absorbing layer,and to nondestructively guess the bandgap depth profile through the refinement of the lattice parameters using GIXRD data on the assumption that the changes of the lattice parameters or unit-cell volume follow a good approximation to Vegard’s law.

关键词： Cu(In1-xGax)Se2 absorbing layer Depth profile Glancing incidence X-ray diffraction technique Bandgap grading Vegard’s law