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Properties of ZnO Thin Films Grown on Si (100) Substrates by Pulsed Laser Deposition

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Journal of materials Science & Technology 2010年第11期26卷 973-976页

作者： Young Rae Jang keon-ho Yoo seung min Park Department of Physics Kyung Hee University Department of Chemistry Kyung Hee University

ZnO thin films were grown on Si （100） substrates by pulsed laser deposition using a ZnO *** substrate temperature was varied in the range of room temperature to 800 ℃,and the oxygen partial pressure of 0.1333 Pa （1 m Torr） to 1333 Pa （10 Torr）.The properties of the resulting films were investigated by photoluminescence （PL）,grazing incidence X-ray diffraction （GIXRD）,X-ray photoelectron spectroscopy （XPS）,and field emission scanning electron microscopy （FESEm）.Based on the ultraviolet （UV,～380 nm） to visible emission ratio in the PL spectrum,the optimum growth conditions were determined to be 600 ℃ and 133.3 Pa （1 Torr）,*** oxygen 1s peak in the XPS spectrum was decomposed into two *** peak at lower binding energy increased in intensity with the oxygen partial pressure from 0.1333 Pa （1 m Torr） to 133.3 Pa （1 Torr） while the other peak *** GIXRD curve at the optimum condition showed strong two peaks （002） and （103）.A strong correlation between the （103） peak intensity and the UV emission intensity was found.

关键词： ZnO Pulsed laser deposition Photoluminescence

Influence of the wastewater composition on denitrification and biological P-removal in the S-DN-P process: (c) Dissolved and undissolved substrates

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Journal of Environmental Sciences 2009年第8期21卷 1074-1079页

作者： Hee-Jeong Choi Chul-ho Choi seung-mok Lee Diwakar Tiwari Department of Environmental Engineering Kwandong University Department of Chemistry School of Physical Sciences Mizoram University

The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composition as well to the quantity of the substrates present in wastewater fraction. Three different wastewater fractions are obtained as： raw wastewater, dissolved wastewater （obtained with filtration using 0.45 μm filter）, and undissolved wastewater （i.e., infiltrate obtained by above filtration）. The ratio of P-release/CODtotal-consumption clearly inferred that undissolved wastewater possess very low value i.e., 0.0008 followed by raw wastewater 0.008 and dissolved wastewater 0.03. When this ratio was nearby 0.01, enhanced P-removal was observed. moreover, the ratio of P-uptake to NO3^--N decomposition for raw wastewater was two times for dissolved wastewater. Interestingly, it was observed that the P-removal and denitrification depend not only on the dissolved substrates but also the undissolved substrates present in the wastewater. The result of the P-removal obtained with this S-DN-P process did not show a big difference of 36%, 34% and 30%, respectively, for raw, dissolved and undissolved wastewater.

关键词： denitrification polyhydroxybutyrate sequencing batch biofilm reactor sorption denitrification P-removals

microstructure investigation and multicolor upconversion in Yb3+/Ln3+(Ln=Er/Tm/ho) ions doped α-Sialon

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Progress in Natural Science:materials International 2019年第5期29卷 549-555页

作者： Sang hoon Jeong Yuwaraj k.kshetri seung ho k.m Sung Hun Cho Soo W.Lee Department of Environment and Bio-Chemical Engineering Sun Moon University Research Center for Eco multi-Functional Nano materials Sun Moon University The Institute of Scientific and Industrial Research (ISIR) Osaka University

Yb3+/Ln3+(Ln=Er/Tm/ho)-α-sialon ceramics were fabricated by hot press sintering *** microstructure and luminescent properties were studied by XRD,EDS,HRTEm and photoluminescence *** results showed that the sintered ceramics consisted ofα-Sialon with a trace amount ofβ-Sialon *** frequency upconversion and downconversion properties of Yb3+/Ln3+(Ln=Er/Tm/ho)-α-Sialon ceramics were investigated under 980 nm low-power *** different concentrations of Yb3+/Ln3+(Ln=Er/Tm/ho)produced multicolor emissions characteristics of each Ln3+ion as a result of the energy transfer from Yb3+to Er3+,Tm3+and ho3+*** EDS spectra measurements and mappings showed that the Ln3+ions were well incorporated in theα-Sialon *** evolution of the emission decay behavior has been investigated to understand the energy transfer mechanism.

关键词： α-Sialon hot press sintering Upconversion Energy transfer

Synergetic analysis of springtime air pollution episodes over Gwangju,korea

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Journal of Environmental Sciences 2017年第7期29卷 270-283页

作者： Sung-kyun Shin kwon-ho Lee seung-Shik Park.man Sing Wong Research Institute for Radiation-Satellite(RIRS) Gangneung-Wonju National University(GWNU)Gangneung 25457Republic of Korea Department of Atmospheric and Environmental Sciences(DAES) Gangneung-Wonju National University(GWNU)Gangneung 25457Republic of Korea Department of Environment and Energy Engineering Chonnam National UniversityGwangju 61186Republic of Korea Department of Land Surveying and Geo-Informatics The Hong Kong Polytech UniversityKowloonHong Kong

The characteristics of springtime aerosols,including their optical and microphysical properties,were analyzed for the months of march to may of 2009 in Gwangju（35.23°N,126.84°E）,korea.A high Light Detection and Ranging（LIDAR）-derived aerosol depolarization ratio（δ） of 0.25 ± 0.04 was determined on dust particles during the observation ***？ngstr？m exponent values of the 440–870 nm wavelength pair（？_（440–870）） and single-scattering albedo at 675 nm（Ω_（675）） measured by a CImEL sun/sky radiometer were 0.77 ± 0.19 and 0.95 ±0.01,*** elevated dust layers reached a maximum elevation of 4 km above sea ***/smoke particles that originated from highly populated/industrialized regions could be distinguished by their relatively smaller particle size（？_（440–870） ranged between1.33 and 1.36） and higher light-absorbing（Ω_（675） of 0.92 ± 0.01） *** aerosols are mostly distributed at altitudes 〈 1.2 *** root-mean-square deviation（RmSD） between the aerosol optical depth（AOD,τ） derived from LIDAR_（（τ_（LIDAR））） and from the CImEL sun/sky radiometer_（（τ_（CImEL））） varied with respect to the surface Pm10 *** RmSD between τ_（LIDAR） and τ_（CImEL） was as low as 13% under lower Pm_（10） concentration levels（〈 100 μg/m^3）.In contrast,the RmSD between τ_（LIDAR） and τ_（CImEL） increased three times（~31%） under high surface Pm_（10） concentration levels（〉100 μg/m^3）.These results suggest that the accuracy of τ_（LIDAR） is influenced by specific atmospheric conditions,regardless of its uncertainty.

关键词： LIDAR Sun/sky radiometer mODIS Optical/microphysical properties Aerosol optical depth

Specific oceanographic characteristics and phytoplankton responses influencing the primary production around the Ulleung Basin area in spring

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Acta Oceanologica Sinica 2020年第2期39卷 107-122页

作者： minji Lee Jin ho k.m Yun-Bae k.m Chan hong Park kyoungsoon Shin seung ho Baek South Sea Research Institute Korea Institute of Ocean Science and TechnologyGeoje 53201Korea Ulleungdo/Dokdo Ocean Science Station Korea Institute of Ocean Science and TechnologyUlleungdo 40205Korea Dokdo Research Center East Sea Research InstituteKorea Institute of Ocean Science and TechnologyUljin 36315Korea

The East Sea(Sea of Japan)is a marginal,semi-closed sea in the northwestern *** Ulleung Basin area,which is located near the subpolar front of the East Sea,is known to have high primary production and good fisheries in spring *** episodic wind-driven events during the spring of 2017,horizontal and vertical profiles of physical chemical biological factors were investigated at 29 stations located in the Ulleung Basin *** addition,growth responses of phytoplankton communities to nutrient additions were evaluated by bioassay experiments to understand the fluctuation of phytoplankton *** of strong northwestern wind,phytoplankton biomass was scattered and upwelling phenomenon might be suppressed in this *** phytoplankton abundances in the coastal stations were significantly higher than offshore and island *** contrast,the nutrient and chlorophyll a(Chl a)concentrations and the phytoplankton biomass were quite low in all *** was dominated group(>75.1%for coastal,40.0%for offshore and 43.6%for island stations).In the algal bioassays,the phytoplankton production was stimulated by N *** in vivo Chl a values in the+N and+NP treatments were significantly higher than the values in the control and the+P *** on the field survey,the higher nutrients in coastal waters affected the growth of diatom assemblages,however,little prosperity of phytoplankton was observed in the offshore waters despite the injection of sufficient nutrients in bioassay *** growth of phytoplankton depended on the initial cell *** of results indicated that a dominant northwestern wind led to a limited nutrients condition at euphotic layers,and the low level of biomass supply from the coasts resulted in low primary *** supplying nutrients and introducing phytoplankton through the currents are critical to maintain the high productivity in the Ulleung Basin area of the East Sea.

关键词： Ulleung Basin Ulleungdo and Dokdo spring phytoplankton blooms episodic windstorm algal bioassays primary production

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 k.m 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

Performance studies on an oscillating water column employing a Savonius rotor

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Science China(Technological Sciences) 2011年第7期54卷 1674-1679页

作者： Sandeep k PATEL krishnil RAm m.Rafiuddin AHmED Young-ho LEE Division of mechanical Engineering the University of the South Pacific Division of mechanical and Information Engineering Korea Maritime University Busan Republic of Korea

A new oscillating water column (OWC) design is proposed in this study to incorporate a simpler Savonius type turbine. Conventional OWC devices employ a bi-directional turbine such as a Wells or an Impulse turbine to extract energy from the air. The disadvantages of the Wells turbine include its inability to self start and stalling. The Savonius turbine is much cheaper and is an effective option at low Reynolds numbers. In the current rectangular OWC device, unlike the circular OWC, the width of entry of the capture chamber can be increased without being influenced by the diameter at the turbine section. To improve its primary capture efficiency, the front and rear walls of the OWC are inclined to minimize reflection. The Savonius rotor characteristics are studied with respect to the change in frequency of the incoming waves. The rotor rpm is sensitive to wave period and primary conversion efficiency while changes in depth only affect the rotor rpm at lower frequencies. The Savonius rotor shows promising results and can be incorporated into large scale OWC devices to reduce costs of the turbine component of the system.

关键词： wave energy Savonius rotor oscillating water column inclined chamber

Electrically driven, phosphor-free, white light-emitting diodes using gallium nitride-based double concentric truncated pyramid structures

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Light(Science & Applications) 2016年第1期5卷 665-670页

作者： seung-Hyuk Lim Young-ho ko Christophe Rodriguez Su-Hyun Gong Yong-hoon Cho Department of Physics and kI for the NanoCentury Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-guDaejeon 34141Korea Electronics and Telecommunications Research Institute(ETRI) 218 Gajeong-roYuseong-guDaejeon 34129Korea The Laboratoire Nanotechnologies Nanosystémes(LN2)-CNRS UmI-3463 Institut Interdisciplinaire d’Innovation Technologique(3IT)Universitéde Sherbrooke3000 boulevard UniversitéJ1K 0A5QCCanada

White light-emitting diodes(LEDs)are becoming an alternative general light source,with huge energy savings compared to conventional ***,white LEDs using phosphor(s)suffer from unavoidable Stokes energy converting losses,higher manufacturing cost,and reduced thermal ***,we demonstrate electrically driven,phosphor-free,white LEDs based on three-dimensional gallium nitride structures with double concentric truncated hexagonal *** electroluminescence spectra are stable with varying *** origin of the emission wavelength is studied by cathodoluminescence and high-angle annular dark field scanning transmission electron microscopy *** variation of the carrier injection efficiency is also investigated by a comparative analysis between spatially resolved photoluminescence and electroluminescence.

关键词： indium gallium nitride light-emitting diodes phosphor-free three-dimensional structures white color

Dual-frequency piezoelectric micromachined ultrasound transducer based on polarization switching in ferroelectric thin films

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microsystems & Nanoengineering 2023年第5期9卷 233-243页

作者： Jin Soo Park Soo Young Jung Dong Hun k.m Jung ho Park ho Won Jang Tae Geun k.m seung-Hyub Baek Byung Chul Lee Bionics Research Center Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Electrical Engineering Korea UniversitySeoul 02841Republic of Korea Center for Electronic materials Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of material Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Division of Bio-medical Science and Technology KIST SchoolUniversity of Science and Technology(UST)Seoul 02792Republic of Korea kHU-kIST Department of Converging Science and Technology Kyung Hee UniversitySeoul 02447Republic of Korea

Due to its additional frequency response,dual-frequency ultrasound has advantages over conventional ultrasound,which operates at a specific frequency ***,a tunable frequency from a single transducer enables sonographers to achieve ultrasound images with a large detection area and high *** facilitates the availability of more advanced techniques that simultaneously require low-and high-frequency ultrasounds,such as harmonic imaging and image-guided *** this study,we present a novel method for dual-frequency ultrasound generation from a ferroelectric piezoelectric micromachined ultrasound transducer(PmUT).Uniformly designed transducer arrays can be used for both deep low-resolution imaging and shallow high-resolution *** switch the ultrasound frequency,the only requirement is to tune a DC bias to control the polarization state of the ferroelectric *** vibration of the PmUT membrane strongly depends on the polarization state,producing low-and high-frequency ultrasounds from a single excitation *** strategy for dual-frequency ultrasounds meets the requirement for either multielectrode configurations or heterodesigned elements,which are integrated into an ***,this technique significantly reduces the design complexity of transducer arrays and their associated driving circuits.

关键词： piezoelectric ferroelectric enable