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Size and temperature effects on electric properties of CdTe/ZnTe quantum rings

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Chinese Physics B 2011年第9期20卷 450-455页

作者： woo-Pyo Hong Seoung-Hwan Park Department of Electronics Engineering Catholic University of DaeguHayangKyeongbuk 712-702Korea

The electronic properties of CdTe/ZnTe quantum rings （QRs） are investigated as functions of size and temperature using an eight-band strain-dependent k.p Hamiltonian. The size effects of diameter and height on the strain distributions around the QRs are studied. We find that the interband transition energy, defined as the energy difference between the ground electronic and the ground heavy-hole subbands, increases with the increasing QR inner diameter regardless of the temperature, while the interband energy decreases with the increasing QR height, This is attributed to the reduction of subband energies in both the conduction and the valence bands due to the strain effects. Our model, in the framework of the finite element method and the theory of elasticity of solids, shows a good agreement with the temperature-dependent photoluminescence measurement of the interband transition energies.

关键词： quantum ring eight-band k.p model finite-element method strain and temperatureeffects electronic structure

A Routing Protocol for Urban Vehicular Multi-hop Data Delivery

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Chinese Journal of Electronics 2016年第2期25卷 348-356页

作者： CHANG Sang-woo LEE Sang-sun Department of Electronic Engineering Hanyang University

Vehicular ad-hoc network(VANET) has distinctive environments such as highly dynamic topology, frequently disconnected network, hard delay constraints for safety-related application, and various communications environments based on highway or urban traffic scenarios. Therefore, development of a suitable routing protocol that considers these characteristics of VANET should be needed. In this paper we propose the improved distance-based VANET routing protocol in urban traffic environments. We apply approaches to multi-hop broadcast scheme for reliable packet dissemination in the intersection and stable route decision scheme based on the adaptive waiting time. The performance is evaluated under simulation which is implemented with the Manhattan urban traffic model. The results show the improved performance as compared with other protocols.

关键词： Distance-based routing protocol Vehicle-to-vehicle communication Waiting time Urban traffic environments Vehicular ad-hoc network(VANET)

Dislocation characteristics and dynamic recrystallization in hot deformed AM30 and AZ31 alloys

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Journal of Magnesium and Alloys 2022年第12期10卷 3495-3505页

作者： Hyeon-woo Son Soong-Keun Hyun Metallic Materials Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea

Zn addition to Mg alloys activates non-basal slip or twinning with solute softening *** the other hand,the effects of the Zn solute on the macroscopic dislocation behavior and dynamic recrystallization are not completely ***,it is unclear ifslip can be affected by changes in the c/a ratio of solute *** study was conducted to understand the solute strengthening of Zn addition and its effects on the dislocation characteristics and dynamic recrystallization.A hot torsion test was performed on both AM30 and AZ31 alloys up to a high strain to investigate the Zn solute effect on the dislocation characteristics and dynamic *** dislocation components of the hot torsioned alloys were evaluated by X-ray line profile analysis and electron backscatter *** results showed that the Zn solutes slightly accelerate strain accumulation at the initial stages of hot deformation,which accelerated recrystallization at high *** dislocation characteristics were changed dynamically by Zn addition:fortified-type slip,dislocation arrangement and strain anisotropy *** most important point was that the dislocation characteristics were changed dramatically at the critical strain for recrystallization and high strain *** addition of Zn also acted greatly in these strain *** indicates that the rapid formation of-type slip at the serrated grain boundaries occurs at the initiation of dynamic recrystallization and the increase in the grain triple junction because grain refinement has a great influence on the dislocation characteristics at high strain.

关键词： Magnesium alloy X-ray line profile Solid solution Dislocation density Dynamic recrystallization

Bright and stable near-infrared perovskite light emitters supported by multifunctional molecule design strategy

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Light(Science & Applications) 2023年第10期12卷 1995-1997页

作者： Joo Sung Kim Tae-woo Lee SN Display Co.Ltd. SeoulRepublic of Korea Soft Foundry Seoul National UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSchool of Chemical and Biological EngineeringInstitute of Engineering ResearchSeoul National UniversitySeoulRepublic of Korea

Perovskite light emitters can realize bright,stable and efficient light-emitting diodes through a molecular design strategy that enables strong endurance on high-current operation.

关键词： emitter light diodes

Radiative life time of an exciton confined in a strained GaN/Ga_(1-x)Al_xN cylindrical dot:built-in electric field effects

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Chinese Physics B 2011年第7期20卷 367-372页

作者： Chang woo Lee A.John Peter Department of Chemical Engineering and Green Energy Center College of EngineeringKyung Hee University1 SeochunGihungYonginGyeonggi 446-701Republic of Korea Department of Physics Government Arts and Science CollegeMelur-625106India

The binding energy of an exciton in a wurtzite GaN/GaAlN strained cylindrical quantum dot is investigated theoretically. The strong built-in electric field due to the spontaneous and piezoelectric polarizations of a GaN/GaAlN quantum dot is included. Numerical calculations are performed using a variational procedure within the single band effective mass approximation. Valence-band anisotropy is included in our theoretical model by using different hole masses in different spatial directions. The exciton oscillator strength and the exciton lifetime for radiative recombination each as a function of dot radius have been computed. The result elucidates that the strong built-in electric field influences the oscillator strength and the recombination life time of the exciton. It is observed that the ground state exciton binding energy and the interband emission energy increase when the cylindrical quantum dot height or radius is decreased, and that the exciton binding energy, the oscillator strength and the radiative lifetime each as a function of structural parameters （height and radius） sensitively depend on the strong built-in electric field. The obtained results are useful for the design of some opto-photoelectronic devices.

关键词： quantum dot donor bound excitons oscillator strength

Organic solar cells for indoor power generation

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Science China Chemistry 2020年第1期63卷 1-2页

作者： Hwa Sook Ryu Han Young woo Department of Chemistry College of Science Korea University

During last decades,organic solar cells(OSCs)have achieved remarkable advancements via extensive studies on the optimization of photovoltaic donor/acceptor(D/A)materials,device fabrication,and the D/A bulk heterojunction *** conversion efficiencies(PCEs)up to〜16%for single junction cells and over 17%PCEs were successfully demonstrated for tandem OSC devices[1,2].OSCs may find real industrial applications soon,including building integrated photovoltaics,portable power sources and indoor power generation for low power consumption electronic devices(i.e.,internet of things(IOT)sensors).Among them,indoor applications have great potentials because OSCs can convert indoor lights into electricity more efficiently compared to inorganic counterparts[3].

关键词： D/A power portable

Enhanced refolding of lysozyme with imidazolium-based room temperature ionic liquids: Effect of hydrophobicity and sulfur residue

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Science China Chemistry 2012年第8期55卷 1657-1662页

作者： BAE Sang-woo CHANG woo-Jin KOO Yoon-Mo HA Sung Ho Department of Biological Engineering Inha University Incheon 402-751 Republic of Korea Department of Mechanical Engineering School of Freshwater Sciences University of Wisconsin-Milwaukee Milwaukee WI 53201-0413 USA Department of Chemical Engineering and Nano-Bio Technology Hannam University Daejeon 305-811 Republic of Korea

The expression of recombinant proteins in microorganism frequently leads to the formation of insoluble aggregates, inclusion bodies （IBs）. Thus, the additional in vitro protein refolding process is required to convert inactive IBs into water-soluble active proteins. This study investigated the effect of sulfur residue and hydrophobicity of imidazolium-based room temperature ionic liquids （RTILs） on the refolding of lysozyme as a model protein in the batch dilution method which is the most commonly used refolding method. When lysozyme was refolded in the refolding buffer containing [BF4]-based RTILs with a systematic variety of alkyl chain on cations varying from two to eight, less hydrophobic imidazolium cations having shorter alkyl chains were effective to facilitate lysozyme refolding. Compared to the conventional refolding buffer, 2 times higher lysozyme re- folding yield was obtained in l-ethyl-3-methylimidazolium tetrafluoroborate （[EMIM][BF4]） containing refolding buffer. The refolding yield of lysozyme was even more increased by 2.5 times when 1-butyl-3-methylimidazolium methylsulfate （[BMIM][MS]） containing sulfur residue on anion was used. The sulfur residue in [BMIM][MS] is supposed to improve the refolding yield of lysozyme which has 4 intrarnolecular disulfide bonds. For dilution-based refolding of lysozyme, the opti- mum concentrations of RTILs in refolding buffer were found to be 1.0 M [EMIM][BF4] and 0.5 M [PMIM][MS], respectively. The optimum temperate for dilution-based refolding of lysozyme with RTILs was 4 ℃.

关键词： protein refolding room temperature ionic liquid dilution refolding lysozyme hydrophobicity sulfur

Investigation of Domain Wall Velocity to External Fields for High-Quality Waveguide-Type Periodically Poled LiNbO_(3) Fabrication

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Journal of Rare Earths 2006年第Z1期24卷 131-135页

作者： Soo woo Kwon woo Seok Yang H M Lee woo Kyung Kim Hang Yong Lee Dae Ho Yoon Yo Seung Song Department of Materials Engineering Hankuk Aviation UniversityGoyang 412-791Korea Nano Bio-Photonics Team Korea Electronics Technology InstituteBundang 463-816Korea Department of Advanced Material Engineering Sungkyunkwan UniversitySuwon 440-746Korea

The Ti-doped waveguide-type periodically poled LiNbO_(3)(PPLN)were fabricated and the dependence of domain wall velocity on an external field applied for domain inversion was *** whole polarization reversal process was computer-controlled to regulate domain wall expansion at a feedback time shorter than 5μ*** coercive voltage and several values of excess voltage were applied on 500μm-thick wafers serially connected to a 1-MOhm external resistor which had an effect of the poling current reduction,*** deceleration of domain wall *** domain wall velocity is sensitive to the poling voltage,precisely speaking,to the excess *** domain wall velocities were 28.70,16.02 and 5.75μm·s^(-1)under poling field of 23.5,22.0 and 21.0 kV·mm^(-1),***,average duty cycle of PPLN is about 49.93%.

关键词： periodically poled lithium niobate coerciv field duty cycle domain wall velocity quasi phase matching

Characteristics of gastric cancer recurrence five or more years after curative gastrectomy

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Chinese Journal of Cancer Research 2016年第5期28卷 503-510页

作者： Chang-Hyun Shin woo-Yong Lee Seung-woo Hong Yeo-Goo Chang Department of Surgery Ilsan Paik HospitalInje University College of Medicine Department of Surgery Seoul Paik HospitalInje University College of Medicine

Objective： To investigate the characteristics of recurrences that occurred 5 or more years after curative resection for gastric ***： We analyzed recurrences among 1,299 patients with gastric cancer who underwent curative operations at the Department of Surgery, Inje University Seoul Paik Hospital between September 1998 and December 2002. Recurrences were classified as within 2 years （early）, 2-5 years （intermediate）, and more than 5 years （late） after gastrectomy. The clinicopathologic findings of the patients with late recurrence were compared with those of patients in the other two recurrence groups, with special reference to the patterns of recurrence. Both univariate and multivariate analyses were performed, incorporating factors such as operation type, T-stage, N-stage, stage, lymphatic invasion, neural invasion, histology, tumor size, and recurrence ***： At the time of last follow-up, recurrence occurred in 266 （20.5%） patients. Recurrence times were classified as 〈2 years （182 patients）, 2-5 years （61 patients）, or 〉5 years （23 patients）. The late recurrence rate was 8.6%. The occurrence of recurrence 〉5 years after gastrectomy was significantly correlated with age, operation type, T-stage, N-stage, stage, lymphatic invasion, neural invasion, histology, tumor size, location and recurrence site （P〈0.05）. The main recurrence patterns in the 23 patients with late recurrence were locoregional metastasis （10 patients, 43.5%）, peritoneal seeding （8 patients, 34.8%）, hematogenous metastasis （2 patients, 8.7%）, and multiple metastasis （3 patients, 13.0%）. A multivariate analysis showed that larger tumor size and younger age were independent prognostic factors for late recurrence. Additionally, locoregional and peritoneal recurrences were significantly more common than hematogenous recurrences. Conclusions： Although late recurrence was uncommon, younger age and larger tumor size were associated with high risk. Follow-up surveillance is recommended

关键词： Curative surgery gastric cancer gastrectomy late recurrence recurrence