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Wyszukujesz frazę "Choi, M." wg kryterium: Autor


Tytuł:
Influence of InAs Coverage on Transition of Size Distribution and Optical Properties of InAs Quantum Dots
Autorzy:
Kim, G.
Jeon, S.
Cho, M.
Choi, H.
Kim, D.
Kim, M.
Kwon, Y.
Choe, J.
Kim, J.
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1535820.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Hi
68.37.Ps
78.55.Cr
78.67.Hc
Opis:
The influence of InAs coverage on the formation of self-assembled quantum dots grown by molecular-beam epitaxy was investigated by atomic force microscopy and photoluminescence measurements. As the InAs coverage increased from 2.0 to 3.0 monolayers, the quantum dot density decreased from 1.1 × $10^{11}$ to 1.36 × $10^{10} cm^{-2}$. This result could be attributed to the coalescence of neighboring small InAs quantum dots resulting in the formation of much larger InAs quantum dots with lower quantum dot density. Atomic force microscopy results revealed that as the InAs quantum dot coverage increased, the transition of size distribution of InAs quantum dots from single-modal to multimodal occurred. The temperature-dependent photoluminescence spectra showed that the photoluminescence spectra red shifted and the photoluminescence peak intensity decreased as the InAs coverage increased. The thermal activation energy was strongly dependent on the InAs coverage, and for InAs quantum dots with 3.0 ML thick InAs coverage, this energy was estimated to be 147 meV.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 673-676
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Properties of Multi-Stacked InAs Quantum Dots Embedded in GaAs/InGaAs Strained Layer and its Annealing Behaviors
Autorzy:
Kim, D.
Kim, G.
Jeon, S.
Cho, M.
Choi, H.
Kim, M.
Lee, D.
Kim, J.
Eom, G.
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1537752.pdf
Data publikacji:
2010-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Hc
78.55.Cr
81.05.Ea
Opis:
Multi-stacked InAs QDs embedded in ten periods of GaAs/$In_{0.1}Ga_{0.9}As$ strained layers were grown by MBE and their optical properties were investigated by using PL spectroscopy. For the QDs embedded in ten periods of GaAs/$In_{0.1}Ga_{0.9}As$ strained layers, the PL intensity is enhanced about 4.7 times and a narrower FWHM of 26 meV is observed compared to those of the conventional multi-stacked QDs. The PL spectra of the InAs QDs show blue-shifts of about 50 meV with increasing annealing temperature up to 850°C. At annealing temperature of 600°C, the FWHM of the PL peak is reduced to 16 meV and PL intensity is enhanced compared to those of the as-grown sample, which indicates improvement of size uniformity and crystal quality of the QDs.
Źródło:
Acta Physica Polonica A; 2010, 117, 6; 941-944
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer
Autorzy:
Kim, M.
Jin, S.
Choi, H.
Kim, G.
Yim, K.
Kim, S.
Nam, G.
Yoon, H.
Kim, Y.
Lee, D.
Kim, Jin
Kim, Jong
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1505152.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
81.15.Gh
Opis:
A heavily Si-doped GaN/polymer hybrid structure with p-type poly(3,4-ethylene-dioxythiophene):beta-1,3-glucan (PEDOT nanoparticle) interface layer has been fabricated. The Si-doped GaN thin film with carrier concentration of 1 × $10^{19} cm^{-3}$ was grown by metal-organic chemical vapor deposition. The PEDOT nanoparticle with various sizes ranging from 60 to 120 nm was synthesized via a miniemulsion polymerization process. The electrical conductivity of the PEDOT nanoparticle is less than 1.2 S/cm. The current-voltage (I-V) characteristic of the hybrid structure shows diode-like behavior. The I-V characteristic was examined in the framework of the thermionic emission model. The ideality factor of the structure without PEDOT nanoparticle interface layer is 12.9. However, the ideality factor of the hybrid structure with PEDOT nanoparticle interface layer is obtained as 1.9. The value of ideality factor is dramatically decreased by inserting the PEDOT nanoparticle interface layer.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 875-879
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-velocity impact characteristics of composite plates with shape memory alloy wires
Niskoprędkościowe charakterystyki uderzeniowe płyt kompozytowych zawierających włókna ze stopów z pamięcią kształtu
Autorzy:
Rim, M.-S.
Kim, E.-H.
Lee, I.
Choi, I.-H.
Ahn, S.-M.
Koo, K.-N.
Bae, J.-S.
Roh, J.-H.
Powiązania:
https://bibliotekanauki.pl/articles/279293.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
shape memory alloy
SMAHC
composite
low-velocity impact
impact resistance
Opis:
To investigate impact characteristics of shape memory alloy hybrid com- posites (SMAHC), several experiments were performed. Tensile tests of shape memory alloy (SMA) wires were carried out to investigate thermomechanical properties, and low-velocity impact tests of SMAHC plates and conventional composite plates without SMAs at the critical energy level. low-velocity impact tests of several types of composite plates, including composite plates with embedded SMAs/Fe/Al wires and conventional composite plates, were also done. Results of these experiments show that embedding SMAs in a composite plate can improve the impact resistance. Lastly, low-velocity impact tests of SMAHC plates with SMA wires embedded at different positions through the thickness were performed in an effort to improve the impact resistance. Embedding SMA wires at a lower position in the composite plates was the most effective for improving the impact resistance.
Do analizy charakterystyk uderzeniowych hybrydowych kompozytów SMAHC zwierających włókna SMA ze stopów wykazujących efekt pamięci kształtu przeprowadzono szereg badań eksperymentalnych. Przeprowadzono próby na rozciąganie włókien SMA w celu zbadania ich właściwości termomechanicznych oraz niskoprędkościowe testy uderzeniowe płyt SMAHC oraz konwencjonalnych płyt laminowanych przy energii krytycznej. Wykonano także testy dla płyt kompozytowych zawierających włókna SMA/Fe/Al. Rezultaty doświadczeń pokazały, że wbudowanie w strukturę laminatu włókien SMA może zwiększyć odporność kompozytu na obciążenie uderzeniowe. Opisano również badania eksperymentalne płyt SMAHC z włóknami SMA wbudowanymi na różnej głębokości. Wykazano, że najlepsze parametry posiadają kompozyty z włóknami umieszczonymi możliwie daleko od uderzanej powierzchni.
Źródło:
Journal of Theoretical and Applied Mechanics; 2011, 49, 3; 841-857
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoluminescence Studies of Aluminum Nitride Nanowires
Autorzy:
Yang, J.
Na, H.
Kim, H.
Kebede, M.
Choi, R.
Jeong, J.
Lee, C.
Powiązania:
https://bibliotekanauki.pl/articles/1505466.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
78.55.-m
Opis:
We report the production of AlN nanowires by the thermal heating method, for exploring their photoluminescence properties. The room-temperature photoluminescence properties were investigated with different annealing environment. While broad emissions with peaks at around 2.45 and 2.95 eV were obtained from both unannealed and annealed samples, the additional 2.1 eV peak was found from the annealed samples. We have suggested the possible emission mechanisms based on the assumption that both 2.45 eV peak and 2.1 eV peak are ascribed to the nitrogen vacancies. Annealing in N_2 environment exhibited lower intensities of 2.45 eV peak and 2.1 eV peak in comparison to those in Ar environment, presumably due to the suppression of nitrogen vacancies.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 125-127
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ca2plus waves and ROS in long distance root-to-shoot signalling
Autorzy:
Choi, W.
Toyota, M.
Hilleary, R.
Swanson, S.
Gilroy, S.
Powiązania:
https://bibliotekanauki.pl/articles/80330.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
reactive oxygen species
peptide
signalling system
plant stress
stress tolerance
gene expression
signalling network
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxide Formation In Metal Injection Molding Of 316L Stainless Steel
Tworzenie tlenków podczas wtryskiwania proszku stali nierdzewnej 316L
Autorzy:
Jang, J. M.
Lee, W.
Ko, S.-H.
Han, C.
Choi, H.
Powiązania:
https://bibliotekanauki.pl/articles/351352.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
powder injection molding
sintering
316L stainless steel
sintering atmosphere
micro parts
wtryskiwanie proszku
spiekanie
stal nierdzewna 316L
mikro-część
Opis:
The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1281-1285
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recovery Of Valuable Metals In Tin-Based Anodic Slimes By Carbothermic Reaction
Odzysk cennych metali ze szlamów anodowych na bazie Sn metodą reakcji karbotermicznej
Autorzy:
Han, C.
Kim, Y.-M.
Son, S. H.
Choi, H.
Kim, T. B.
Kim, Y. H.
Powiązania:
https://bibliotekanauki.pl/articles/352796.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tin
anodic slime
carbothermic reduction
carbon
recovery
cyna
szlam anodowy
reakcja karbotermiczna
węgiel
odzysk metali
Opis:
This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail of carbothermic reaction, thermodynamic calculation was carried out and compared with experiments. From thermodynamic calculation and experiment, it was confirmed that Sn-based anodic slime could be reduced by controlling temperature and amount of carbon. However, any tendency between the reduction temperature and carbon content for the reduction reaction was not observed.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1213-1216
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simplified procedure for the free vibration analysis of rectangular plate structures with holes and stiffeners
Autorzy:
Cho, D. S.
Vladimir, N.
Choi, T. M.
Powiązania:
https://bibliotekanauki.pl/articles/260556.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
energy approach
plate with hole
stiffened panel
thick plate
VAPS software
free vibration analysis
Opis:
Thin and thick plates, plates with holes, stiffened panels and stiffened panels with holes are primary structural members in almost all fields of engineering: civil, mechanical, aerospace, naval, ocean etc. In this paper, a simple and efficient procedure for the free vibration analysis of such elements is presented. It is based on the assumed mode method and can handle different plate thickness, various shapes and sizes of holes, different framing sizes and types as well as different combinations of boundary conditions. Natural frequencies and modes are determined by solving an eigenvalue problem of a multi-degree-of-freedom system matrix equation derived by using Lagrange’s equations. Mindlin theory is applied for a plate and Timoshenko beam theory for stiffeners. The applicability of the method in the design procedure is illustrated with several numerical examples obtained by the in-house developed code VAPS. Very good agreement with standard commercial finite element software is achieved.
Źródło:
Polish Maritime Research; 2015, 2; 71-78
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A dynamic bi-orthogonal field equation approach to efficient Bayesian inversion
Autorzy:
Tagade, P. M.
Choi, H. L.
Powiązania:
https://bibliotekanauki.pl/articles/330516.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
Bayesian framework
stochastic partial differential equation
Karhunen–Loève expansion
generalized polynomial chaos
dynamically biorthogonal field equations
ramy Bayesa
stochastyczne równanie różniczkowe
przekształcenie Karhunena-Loeve'a
chaos wielomianowy
Opis:
This paper proposes a novel computationally efficient stochastic spectral projection based approach to Bayesian inversion of a computer simulator with high dimensional parametric and model structure uncertainty. The proposed method is based on the decomposition of the solution into its mean and a random field using a generic Karhunen–Loève expansion. The random field is represented as a convolution of separable Hilbert spaces in stochastic and spatial dimensions that are spectrally represented using respective orthogonal bases. In particular, the present paper investigates generalized polynomial chaos bases for the stochastic dimension and eigenfunction bases for the spatial dimension. Dynamic orthogonality is used to derive closed-form equations for the time evolution of mean, spatial and the stochastic fields. The resultant system of equations consists of a partial differential equation (PDE) that defines the dynamic evolution of the mean, a set of PDEs to define the time evolution of eigenfunction bases, while a set of ordinary differential equations (ODEs) define dynamics of the stochastic field. This system of dynamic evolution equations efficiently propagates the prior parametric uncertainty to the system response. The resulting bi-orthogonal expansion of the system response is used to reformulate the Bayesian inference for efficient exploration of the posterior distribution. The efficacy of the proposed method is investigated for calibration of a 2D transient diffusion simulator with an uncertain source location and diffusivity. The computational efficiency of the method is demonstrated against a Monte Carlo method and a generalized polynomial chaos approach.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 2; 229-243
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Grain Boundary Morphologies on Stress Corrosion Cracking of Alloy 600
Autorzy:
Kim, H. P.
Choi, M. J.
Kim, S. W.
Kim, D. J.
Lim, Y. S.
Hwang, S. S.
Powiązania:
https://bibliotekanauki.pl/articles/352569.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
alloy 600
NaOH
stress corrosion cracking
grain boundary morphologies
Opis:
Effects of grain boundary morphologies on stress corrosion cracking (SCC) of Alloy 600 have been studied in 40% NaOH at 315°C using C-ring specimens. The configuration of the grain boundary and the intergranular carbide density were controlled by heat treatment. SCC tests were performed at +150 mV above the corrosion potential. The specimen with a serrated grain boundary showed higher SCC resistance than that with a straight grain boundary. This appears to be caused by the fact that the specimen with the serrated grain boundary has longer SCC path. SCC resistance also increased with intergranular carbide density probably due to enhanced relaxation of stress at intergranular carbide.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1415-1419
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxidation Behavior of Steel with Cr Content and Water Flow Rate
Autorzy:
Kim, D.-J.
Kim, K. M.
Shin, J. H.
Cheong, Y. M.
Lee, E. H.
Lee, G. G.
Kim, S. W.
Kim, H. P.
Choi, M. J.
Lim, Y. S.
Hwang, S. S.
Powiązania:
https://bibliotekanauki.pl/articles/351548.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
steel
flow accelerated corrosion
Cr content
flow rate
surface oxides
Opis:
Fast water flow facilitates ferrous ion transport leading to flow accelerated corrosion (FAC) of carbon steel and the possibility of a large accident through a failure of a secondary pipe in a nuclear power plant. Ion transport is directly linked to oxide properties such as the thickness, chemical composition and porosity. This work deals with a precise observation of the cross section of the corroded specimen focusing on an oxide passivity and its thickness using SEM (scanning electron microscope) and TEM (transmission electron microscope) as well as an apparent weight loss and a surface observation for the specimens corroded using a rotating cylindrical electrode autoclave system in pure water of pH 7 at 150°C having dissolved oxygen below 1 ppb within a flow rate range of 0 to 10 m/s. The Cr content in steel was changed from 0.02 to 2.4 wt%. Increasing the Cr content in the alloy, the FAC rate and oxide thickness decreased. The oxide porosity tends to decrease with the Cr content and immersion time owing to the development of Cr containing oxide. The oxidation behavior is not changed with the immersion time.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1383-1387
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Range resolution improvement of range-gated vision system in backscattering hazy environments
Autorzy:
Park, S.-K.
Choi, I.-Y.
Baik, S.-H.
Jeong, K.-M.
Powiązania:
https://bibliotekanauki.pl/articles/174523.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
range-gated vision system
range image
windowed center-of-mass
cross-correlation
Gaussian window
Opis:
A range-gated vision system simultaneously provides two-dimensional and range images because its light intensity contains the reflectance as well as depth information. The range-resolution of the system is usually inversely proportional to the induced backscattering noise. In this paper, a range imaging technique is proposed to precisely measure range information from highly backscattering foggy environments. A windowed center-of-mass position extracted from the peak area of a cross-correlation signal of two signals, a Gaussian window signal in reduced size and a range-gated signal according to distance, is adopted as the range depth. The proposed measuring technique provides more robust and more precise range information than conventional measuring techniques for hazy targets by virtue of the reduction of backscattering bias noise usually induced by airborne particles. The experimental results and the signal processing procedures to acquire precise range information from hazy targets are described in this paper.
Źródło:
Optica Applicata; 2017, 47, 4; 533-543
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Diffusion of 57Co into Rh Foil for Preparing Mössbauer Source
Autorzy:
Uhm, Y. R.
Kim, J. J.
Choi, S. M.
Son, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/352775.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Mössbauer source
diffusion
electroplating
57Co/Rh
Opis:
To establish the coating conditions for 57 Co, non-radioactive Co ions are dissolved in an acid solution and electroplated on to a rhodium plate. The thermal diffusion of electroplated Co into a rhodium matrix was studied to apply a 57 Co Mössbauer source. The procedure to form a Co deposited onto Rh foil was established using two different electroplating baths: the acid-based buffer (pH 3) containing boric acid, sodium chloride, and saccharin, and the alkaline-based buffer (pH 10) containing hydrazine hydrate and ammonium citrate. The influence of different annealing conditions was investigated. From the results, the best diffusion degree of electrodeposited Co onto the rhodium matrix was obtained in an annealing process performed at 1100°C for 3 h in vacuum over 10-5 hPa.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1249-1252
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł

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