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Thin film processing and multiferroic properties of Fe-BaTiO_3 hybrid composite

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 92-95页

作者： Pan YANG Jin-song ZHU Jai-Yeoul lee hee young lee School of Materials Science and Engineering Yeungnam University Gyeongsan 712-749 Korea National Laboratory of Solid State Microstructures Department of Physics Nanjing University Nanjing 210093 China

Multiferroic bi-layer Fe/BaTiO3 （BTO） thin films were successfully deposited on Pt（200）/MgO（100） substrates using ion beam sputter deposition （1BSD）, and the mutiferroic properties were studied at room temperature. X-ray diffraction （XRD） analyses showed that BTO films were c-axis oriented and epitaxially grown on platinum coated MgO substrates, and （110） epitaxial Fe films were subsequently grown on （001） BTO films. Fe/BTO bi-layer films showed good ferroelectric and ferromagnetic properties at room temperature and the multiferroic coupling was observed, which should be attributed to the hybridization of Fe and Ti occurring at the ferromagnetic-ferroelectric interface.

关键词： multiferroic effect ferroelectricity magnetic properties magnetoelectric effect

Observational Study of Surface Wind along a Sloping Surface over Mountainous Terrain during Winter

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Advances in Atmospheric Sciences 2018年第3期35卷 276-284页

作者： young-hee lee Gyuwon lee Sangwon JOO Kwang-Deuk AHN Department of Astronomy and Atmospheric Sciences Kyungpook National University Numerical Data Application Division Numerical Modeling Center

The 2018 Winter Olympic and Paralympic Games will be held in Pyeongchang, Korea, during February and March. We examined the near surface winds and wind gusts along the sloping surface at two outdoor venues in Pyeongchang during February and March using surface wind data. The outdoor venues are located in a complex, mountainous terrain, and hence the near-surface winds form intricate patterns due to the interplay between large-scale and locally forced winds. During February and March, the dominant wind at the ridge level is westerly; however, a significant wind direction change is ob- served along the sloping surface at the venues. The winds on the sloping surface are also influenced by thermal forcing, showing increased upslope flow during daytime. When neutral air flows over the hill, the windward and leeward flows show a significantly different behavior. A higher correlation of the wind speed between upper- and lower-level stations is shown in the windward region compared with the leeward region. The strong synoptic wind, small width of the ridge, and steep leeward ridge slope angle provide favorable conditions for flow separation at the leeward toot of the ridge. The gust factor increases with decreasing surface elevation and is larger during daytime than nighttime. A significantly large gust factor is also observed in the leeward region.

关键词： flow separation gust factor leeward region sloping surface

Properties of multilayer gallium and aluminum doped ZnO(GZO/AZO) transparent thin films deposited by pulsed laser deposition process

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 96-99页

作者： Jin-Hyun SHIN Dong-Kyun SHIN hee-young lee Jai-Yeoul lee Department of Materials Engineering Yeungnam University

Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO （1：1） thin film deposited at 400 ~C shows the electrical resistivity of 4.18 x 10 4 ~.cm, an electron concentration of 7.5 x 1020/cm3, and carrier mobility of 25.4 cm2/（V.s）. The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the AI ratio.

关键词： multilayer thin films Ga-doped zinc oxide Al-doped zinc oxide pulsed laser deposition

A density functional theory study of the tunable structure, magnetism and metal-insulator phase transition in VS2 monolayers induced by in-plane biaxial strain

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Nano Research 2015年第4期8卷 1348-1356页

作者： Min Kan Bo Wang young hee lee Qiang Sun Department of Materials Science and Engineering Peking University 8eijing 100871 China Center for Integrated Nanostructure Physics Institute for Basic Science Sungkyunkwan University Suwon 440-746 Korea Department of Physics and Department of Energy Science Sungkyunkwan University Suwon 440-746 Korea School of Mathematical Sciences Peking University Beijing 100871 China Center forAppfied Physics and Technology Peking University Beijing 100871 China

We report a density functional theory study of a phase transition of a VS2 monolayer that can be tuned by the in-plane biaxial strain. This results in both a metal-insulator transition and a low spin-high spin magnetic transition. At low temperature, the semiconducting H-phase is stable and large strain （〉3%） is required to provoke the transition. On the other hand, at room temperature （300 K）, only a small tensile strain of 2% is needed to induce the phase transition from the semiconducting H-phase to the metallic T-phase together with the magnetic transition from high spin to low spin. The phase diagram dependence on both strain and temperature is also discussed in order to provide a better understanding of the phase stability of VS2 monolayers.

关键词： phase transition biaxial strain phase diagram density functional theory(DFT) transition metaldichalcogenide(TMD) materials

Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector

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Nano Research 2021年第6期14卷 1967-1972页

作者： Ui Yeon Won Boo Heung lee young Rae Kim Won Tae Kang Ilmin lee Ji Eun Kim young hee lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics Institute for Basic Science(IBS)Suwon16419Republic of Korea

Graphene(Gr)/Si-based optoelectronic devices have attracted a lot of academic attention due to the simpler fabrication processes,low costs,and higher performance of their two-dimensional(2D)/three-dimensional(3D)hybrid interfaces in Schottky junction that promotes electron-hole ***,due to the built-in potential of Gr/Si as a photodetector,the Iph/Idark ratio is often hindered near zero-bias at relatively low illumination *** is a major drawback in self-powered *** this study,we have demonstrated a self-powered van der Waals heterostructure photodetector in the visible range using a Gr/hexagonal boron nitride(h-BN)/Si structure and clarified that the thin h-BN insertion can engineer asymmetric carrier transport and avoid interlayer coupling at the *** dark current was able to be suppressed by inserting an h-BN insulator layer,while maintaining the photocurrent with minimal decrease at near *** a result,the normalized photocurrent-to-dark ratio(NPDR)is improved more than 104 ***,both Iph/Idark ratio and detectivity,increase by more than 104 times at−0.03 V drain *** proposed Gr/h-BN/Si heterostructure is able to contribute to the introduction of next-generation photodetectors and photovoltaic devices based on graphene or silicon.

关键词： graphene hexagonal boron nitride van der Waals heterostructure self-powered Research

Research on Cavitation Characteristics and Influencing Factors of Herringbone Gear Pump

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2917-2946页

作者： Jinlong Yang Kwang-hee lee Chul-hee lee Department of Mechanical Engineering of Inha University Incheon22212South Korea

Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow *** is one of the main hazards that affect the regular operation of the *** on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,***,there are few cavitation studies on external herringbone gear *** addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow ***,it is urgent to study the cavitation characteristics of external herringbone gear *** with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is *** simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing *** can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be *** example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.

关键词： Herringbone gear pump cavitation rotating speed inlet pressure helix angle TwinMesh

Management of a deviated nose

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Management of a deviated nose

Tuning the inhomogeneous charge transport in ZnO interfaces for ultrahigh on/off ratio top-gated field-effect-transistor arrays

第四届华东六省一市整形外科学术会议暨2007年浙江省整形、美容学术会议

作者： hee-young lee M.D Planning Director Korea social of Aesthetic Surgery Co-Chairman 2~(nd)Congress of Eastern Cosmetic Surgery Attending professor at the Catholic UniversityKorea Director-形 Clinic GeneskinGang-NamSong-PaKwang-JuBang-Bae Ian Clinic

Two units of correction in deviated nose are septal surgery and techniques for modifying the osseocartilagenous vault."As the septum goes,so goes the nose"Thus it is important to repair that provides structure realignment with release of deforming forces causing cartilagenous septal deviation. We will introduce multiple techniques of septal surgery and osteotomy techniques in our clinic.

关键词： Management of a deviated nose

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Nano Research 2020年第11期13卷 3033-3040页

作者： Thanh Luan Phan Dinh Loc Duong Tuan Khanh Chau Sidi Fan Won Tae Kang Thi Suong Le Hyun Yong Song Linfeng Sun Van Tu Vu Min Ji lee Quoc An Vu young hee lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics(CINAP) Institute for Basic Science(IBS)Suwon16419Republic of Korea Department of Energy Science Sungkyunkwan UniversitySuwon16419Republic of Korea Department of Physics Sungkyunkwan UniversitySuwon16419Republic of Korea

The interface between oxide/oxide layers shows an inhomogeneous charge transport behavior,which reveals a high conductivity owing to *** typical example is the hetero-interface between ZnO film and other wide band gap oxides(e.g.,Al_(2)O_(3),TiO_(2),and HfO_(2)).It is thus quite evident that the ZnO/other oxides hetero-interface contains high density electron carriers effectively screening the gate-induced electric ***,an extremely weak gate modulation in ZnO film was showed,resulting in very low on/off ratio of 1.69 in top-gate field-effect-transistor(TG-FET)***,to extend the usage of ZnO TG-FET is not quite possible toward further practical ***,we clarified the correlation of inhomogeneous region in oxide/oxide hetero-junction by systematically *** work suggests that a self-assembly of molecules(SAM)buffer layer is suitable for tuning the inhomogeneous charge transport in ZnO film,which not only reduces the interface trap density,but also effectively enhances the gate electric field modulation at the *** further report the robust fabrication of TG-FET arrays based on ZnO thin film,using an ultra-thin alkylphosphonic acid molecule monolayer as buffer *** device demonstrates a pronounced ultrahigh on/off ratio of≥10^(8),which is 8-order of magnitude higher than that of a device without buffer *** the highly reliable arrays,our device exhibits a high yield of over 93%with an average on/off ratio of^10^(7) across the entire wafer scale,mobility(18.5 cm^(2)/(V·s)),an extended bias-stressing(~2,000 s)and long-stability(~150 days)under ambient conditions.

关键词： zinc oxides thin-film field-effect-transistor self-assembly molecule inhomogeneous charge transport interface engineering

SUMS OF DUAL TOEPLITZ PRODUCTS ON THE ORTHOGONAL COMPLEMENTS OF FOCK-SOBOLEV SPACES

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Acta Mathematica Scientia 2024年第3期44卷 810-822页

作者：陈泳 young Joo lee Department of Mathematics Hangzhou Normal UniversityHangzhou311121China Department of Mathematics Chonnam National UniversityGwangju61186Korea

We consider dual Toeplitz operators on the orthogonal complements of the FockSobolev spaces of all nonnegative real ***,for symbols in a certain class containing all bounded functions,we study the problem of when an operator which is finite sums of the dual Toeplitz products is compact or ***,for bounded symbols,we construct a symbol map and exhibit a short exact sequence associated with the C^(*)-algebra generated by all dual Toeplitz operators with bounded symbols.

关键词： dual Toeplitz operators Fock-Sobolev spaces symbol map