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Settling and dewatering characteristics of granulated methane-oxidizing bacteria

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Journal of Environmental Sciences 2013年第2期25卷 280-286页

作者： kwang Ho Ahn kwang Soo Kim Sung Won Kang Chul Yong Um Won Tae lee kwang Baik Ko Korea Institute of Construction Technology 283Goyangdae-RoIlsanseo-GuGoyang-SiGyeonggi-Do 411-712Korea School of Civil and Environmental Engineering Yonsei UniversitySinchondong 134SudaemunguSeoul 120-749Korea School of Civil and Environmental Engineering Kumoh National Institute of TechnologyDaehak-ro 61GumiGyeongbuk 730-701Korea

We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria （GMOB） after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time （SRT, 10, 15 and 20 days） during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration （SRF） of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance （EPS）, activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.

关键词： methane-oxidizing bacteria dewaterability specific resistance to filtration extracellular polymeric substances

Structurally engineered colloidal quantum dot phosphor using TiO_(2) photonic crystal backbone

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Light(Science & Applications) 2022年第11期11卷 2782-2789页

作者： Hansol lee Tae-Yun lee Yeonsang Park Kyung-Sang Cho Young-Geun Rho hyuck Choo Heonsu Jeon Department of Physics and Astronomy Seoul National UniversitySeoul 08826Republic of Korea Inter-university Semiconductor Research Center Seoul National UniversitySeoul 08826Republic of Korea Department of Physics Chungnam National UniversityDaejeon 34134Republic of Korea Institute of Quantum Systems Chungnam National UniversityDaejeon 34134Republic of Korea Samsung Advanced Institute of Technology Suwon 16678Republic of Korea Institute of Applied Physics Seoul National UniversitySeoul 08826Republic of Korea

Photonic crystal(PhC)phosphor,in which the phosphor material is periodically modulated for an enhancement in color-conversion efficiency via resonant absorption of excitation photons,is a paradigm-shifting structural phosphor ***-dimensional(2D)square-lattice PhC phosphor is currently considered the most advanced platform because of not only its high efficiency,but also its immunity to excitation *** the present study,two major modifications are made to further improve the performance of the 2D PhC phosphor:increasing the refractive index contrast and planarizing the *** index contrast is improved by replacing the PhC backbone material with TiO_(2)whereas the surface planarization is achieved by removing excessive colloidal quantum dots from the *** comparison with the reference phosphor,the upgraded PhC phosphor exhibits~59 times enhanced absorption(in simulations)and~7 times enhanced emission(in experiments),both of which are unprecedentedly *** results not only brighten the viability and applicability of the PhC phosphor but also spur the phosphor development through structural engineering of phosphor materials.

关键词： immunity phosphor backbone

Mechanism of contact pressure-induced friction at the amorphous carbon/alpha olefin interface

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npj Computational Materials 2018年第1期4卷 213-221页

作者： Xiaowei Li Aiying Wang kwang-Ryeol lee Computational Science Center Korea Institute of Science and TechnologySeoul 136-791Republic of Korea Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201P.R.China

Combining an amorphous carbon(a-C)film with a lubricating oil can significantly improve the friction performance and lifetime of moving mechanical ***,the friction mechanism is not well understood owing to a lack of information regarding the structure of the interface when exposed to high contact ***,we select linear alpha olefin,C5H10,as a lubricant and study the evolution of the structure of the a-C/C5H10/a-C sliding interface under contact pressure via reactive molecular dynamics *** results suggest that introducing C5H10 into the a-C/a-C interface reduces the friction coefficient by up to 93% compared with no lubricant,although the lubricating efficiency strongly depends on the contact *** particular,increasing the contact pressure not only induces the binding of the lubricant with a-C,but also facilitates the dissociation of the C5H10 carboncarbon skeleton by specific scissions,which governs the friction *** results disclose the underlying lubrication mechanism and could enable the development of new and effective lubricating systems with long lifetimes.

关键词： friction interface amorphous

Electrocrystallization of Monodisperse Nanocrystal Copper on Highly Oriented Pyrolytic Graphite Electrode

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Chinese Journal of Chemistry 2005年第2期23卷 121-126页

作者：黄令 lee,Eun-Sung KIM,kwang-Bum DepartmentofChemistry XiamenUniversityXiamenFujian361005China DepartmentofMetaUurgicalEngineering YonseiUniversitySeoul120-749SouthKorea

Mechanism of copper electrocrystallization on highly oriented pyrolytic graphite electrode from a solution of 1 mmol/L CuSO 4 and 1.0 mol/L H 2 SO 4 has been studied using cyclic voltammogram and chronoamperometry. The results show that in copper electrodeposition the charge‐transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing centers. Reduction of Cu(II) ions did not undergo underpotential deposition. The initial deposition kinetics of Cu electrocrystallization corresponds to a model including progressive nucleation and diffusion controlled growth. Copper nanocrystals with size of 75.6 nm and relative standard deviation of 9% can be obtained by modulation potential electrodeposition.

关键词： electrocrystallization electrodeposition nucleation and growth nanocrystal copper

Electron beam deposition and characterization of thin film Ti-Ni for shape memory applications

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Rare Metals 2006年第Z2期25卷 237-242页

作者： NOH Hae-Yong JEE kwang-Koo lee Kyu-Hwan lee Young-Kook Department of Metallurgical System Yonsei University Seoul 120-749 KoreaAdvanced Materials Research Center Division of Materials Korea Institute of Science and Technology Cheongryang Seoul 130-650 Korea Advanced Materials Research Center Division of Materials Korea Institute of Science and Technology Cheongryang Seoul 130-650 Korea Department of Metallurgical System Yonsei University Seoul 120-749 Korea

Thin film of Ti-Ni alloy has a potential to perform the microactuation functions required in the microelectromechanical system (MEMS). It is essential, however, to have good uniformity in both chemical composition and thickness to realize its full potential as an active component of MEMS devices. Electron beam evaporation technique was employed in this study to fabricate the thin films of Ti-Ni alloy on different substrates. The targets used for the evaporation were first prepared by electron beam melting. The uniformity of composition and microstructure of the thin films were characterized by electron probe microanalysis (EPMA), Auger electron spectroscopy (AES), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The mechanical property of the thin films was evaluated by the nano-indentation test. The martensitic transformation temperature was measured by differential scanning calorimetry (DSC). It is confirmed that the chemical composition of deposited thin films is identical to that of the target materials. Furthermore, results from depth profiling of the chemical composition variation reveal that the electron beam evaporation process yields better compositional homogeneity than other conventional methods such as sputtering and thermal evaporation. Microstructural observation by TEM shows that nanometer size precipitates are preferentially distributed along the grain boundaries of a few micron size grains. The hardness and elastic modulus of thin films decreases with an increase in Ti contents.

关键词： electron beam evaporation TiNi SMA thin film martensitic transformation reverse martensitic transformation

Effects of fractional-order PI controller on delay margin in single-area delayed load frequency control systems

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 380-389页

作者： Vedat CELIK Mahmut Temel OZDEMIR kwang Y.lee Department of Electrical and Electronics Engineering Faculty of EngineeringFirat UniversityElazigTurkey Department of Electrical and Computer Engineering Baylor UniversityWacoUSA

This study aims to determine the improvement effect on the delay margin if fractional-order proportional integral(PI) controller is used in the control of a singlearea delayed load frequency control(LFC) system. The delay margin of the system with fractional-order PI control has been obtained for various fractional integral orders and the effect of them has been shown on the delay margin as a third controller parameter. Furthermore,the stability of the system that is either under or over the delay margin is examined by generalized modified Mikhailov *** stability results obtained have been confirmed numerically in time domain. It is demonstrated that the proposed controller for delayed LFC system provides more flexibility on delay margin according to integer-order PI controller.

关键词： Delay dependent stability Delay margin Fractional-order proportional integral(PI) Generalized modified Mikhailov criterion Load frequency control with delay

Analysis of the current density characteristics in through-mask electrochemical micromachining(TMEMM) for fabrication of micro-hole arrays on invar alloy film

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Chinese Journal of Aeronautics 2017年第3期30卷 1231-1241页

作者： Da-som JIN kwang-ho CHUN Eun-sang lee School of Mechanical Engineering Inha University Incheon 22212 Republic of Kore Department of Mechanical Engineering Inha University Incheon 22212 Republic of Korea

Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes（OLEDs） because of its low thermal expansion coefficient（1.86 × 10^-6cm/°C）.To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining（TMEMM） was developed and combined with a portion of the photolithography etching *** precise hole shapes,patterned photoresist（PR） film was applied as an insulating *** investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the *** finite element method（FEM） was used to verify the influence of each parameter on the current density on the invar alloy film *** parameters considered were the thickness of the PR mask,inter-electrode gap（IEG）,and electrolyte *** of experiments（DOE） was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current *** was conducted to select the suitable *** experiment was carried out to verify the simulation *** was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.

关键词： Electrochemical Invar alloy film Micromachining OLED shadow mask Photoresist film mask(PR film mask) Through-mask electrochemical micromachining(TMEMM)

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

Effect of stick-slip on magneto-rheological elastomer with a magnetic field

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Friction 2017年第4期5卷 383-391页

作者： Chenglong LIAN kwang-hee lee Jun-wook AN Chul-hee lee Department of Mechanical Engineering Inha University100 InharoNam-guIncheon 22212Republic of Korea Department of Construction Machinery Engineering Inha University100 InharoNam-guIncheon 22212Republic of Korea

This study investigated the stick-slip characteristics of a magneto-rheological elastomer (MRE) against an aluminum ***,the MRE was manufactured,and a stick-slip tester was employed to evaluate the stick-slip performance of the MRE under different velocities and load conditions with and without a magnetic *** fast Fourier transform (FFT) of the friction force of the stick-slip and the roughness of the aluminum plate surface were calculated to confirm the stick-slip *** the tests,the wear surfaces were observed to evaluate the wear properties of the MRE regarding the *** showed that the stick-slip was smaller at lower *** higher velocity,the reduction of the stick-slip under a magnetic field was more clearly ***,the wear reduced with reduced stick-slip under a magnetic field.

关键词： stick-slip friction wear magneto-rheological elastomer