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中国有色金属学会会刊：英文版 2012年第S3期22卷 585-595页

作者： Jung-Min LEE Chan-Joo LEE Kyung-Hun LEE Byung-Min KIM Dongnam Regional Division Korea Institute of Industrial Technology Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the ***,this indirect measurement occasionally leads to inaccurate properties of the indented *** objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation *** relations between the residual indentation profile and n value of the indented material were identified by dimensional ***,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and *** parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after *** were subsequently characterized as dimensionless functions using n and E/σr ***,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

关键词： nano-indentation pile-up sink-in strain hardening exponent FE simulation

Fouling distribution in forward osmosis membrane process

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Journal of Environmental Sciences 2014年第6期26卷 1348-1354页

作者： Junseok Lee Bongchul Kim Seungkwan Hong School of Civil Environmental & Architectural Engineering Korea University

Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis （FO） membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic （alginate） fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter- current flow operation of FO membrane process.

关键词： forward osmosis membrane module length organic fouling fouling reversibility counter-current flow FO operation

Computational approaches for fast generation of digital 3D video holograms(Invited Paper)

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Chinese Optics Letters 2009年第12期7卷 1083-1091页

作者： Seung-Cheol Kim Eun-Soo Kim 3D Display Research Center Department of Electronic Engineering Kwangwoon University

Several approaches for fast generation of digital holograms of a three-dimensional （3D） object have been discussed. Among them, the novel look-up table （N-LUT） method is analyzed to dramatically reduce the number of pre-calculated fringe patterns required for computation of digital holograms of a 3D object by employing a new concept of principal fringe patterns, so that problems of computational complexity and huge memory size of the conventional ray-tracing and look-up table methods have been considerably alleviated. Meanwhile, as the 3D video images have a lot of temporally or spatially redundant data in their inter- and intra-frames, computation time of the 3D video holograms could be also reduced just by removing these redundant data. Thus, a couple of computational methods for generation of 3D video holograms by combined use of the N-LUT method and data compression algorithms are also presented and discussed. Some experimental results finally reveal that by using this approach a great reduction of computation time of 3D video holograms could be achieved.

关键词： LUT Computational approaches for fast generation of digital 3D video holograms CGH

In situ synthesis of chemically bonded NaTi2（PO4）3/rGO 2D nanocomposite for high-rate sodium-ion batteries

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Nano Research 2016年第6期9卷 1844-1855页

作者： Ha-Kyung Roh Hyun-Kyung Kim Myeong-Seong Kim Dong-Hyun Kim Kyung Yoon Chung Kwang Chul Roh Kwang-Bum Kim Department of Material Science & Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seou103722 Republic of Korea Department of Materials Science and Metallurgy University of Cambridge 27 Charles Babbage Road Cambridge CB30FS UK Center for Energy Convergence Korea Institute of Science and Technology 5 Hwarang-ro 14-gil Seongbuk-gu Seou102792 Republic of Korea Energy & Environmental Division Korea Institute of Ceramic Engineering & Technology 101 Soho-ro Jinju-si Gyeongsangnam-do 52851 Republic of Korea

A phase-pure NaTi2（PO4）3/reduced graphene oxide （rGO） nanocomposite was prepared using a microwave-assisted one-pot method and subsequent heat treatment. The well-crystallized NaTi2（PO4）3 nanoparticles （30-40 nm） were uniformly precipitated on rGO templates through Ti-O-C bonds. The chemical interactions between the NaTi2（PO4）3 nanoparticles and rGO could immobilize the NaTi2（PO4）3 nanoparticles on the rGO sheets, which might be responsible for the excellent electrochemical performance of the nanocomposite. The NaTi2（PO4）B/rGO nanocomposite exhibited a specific capacity of 128.6 mA-h.g-1 approaching the theoretical value at a 0.1 C-rate with an excellent rate capability （72.9% capacity retention at 50 C-rate） and cycling performance （only 4.5% capacity loss after 1,000 cycles at a high rate of 10 C）. These properties were maintained even when the electrodes were prepared without the use of an additional conducting agent. The excellent sodium storage properties of the NaTi2（PO4）B/rGO nanocomposite could be attributed to the nano-sized NaTi2（PO4）3 particles, which significantly reduced the transport lengths for Na＋ ions, and an intimate contact between the NaTi2（PO4）3 particles and rGO due to chemical bonding.

关键词： NaTi2(PO4)dreducedgraphene oxide (rGO)nanocomposite chemical bonding energy-efficiency in situ synthesis high-rate sodium-ion batteries

New results on stability criteria for neural networks with time-varying delays

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Chinese Physics B 2011年第5期20卷 163-173页

作者： O.M.Kwon J.W.Kwon S.H.Kim School of Electrical Engineering Chungbuk National University410 SungBong-RoHeungduk-guCheongju 361-763Republic of Korea Department of Computer Engineering Kyungwon UniversitySan 65Sujung-guSungnam 461-701Republic of Korea School of Integrated Technology College of EngineeringYonsei University50 Yonsei-RoSeodaemun-guSeoul 120-749Republic of Korea

In this paper, the problem of stability analysis for neural networks with time-varying delays is considered. By constructing a new augmented Lyapunov-Krasovskii＇s functional and some novel analysis techniques, improved delaydependent criteria for checking the stability of the neural networks are established. The proposed criteria are presented in terms of linear matrix inequalities （LMIs） which can be easily solved and checked by various convex optimization algorithms. Two numerical examples are included to show the superiority of our results.

关键词： neural networks time-varying delays stability Lyapunov method

Improved speech absence probability estimation based on environmental noise classification

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Journal of Central South University 2012年第9期19卷 2548-2553页

作者： SON Young-ho LEE Sang-min Department of Electronic Engineering Inha University Institute for Information and Electronics Research Inha University

An improved speech absence probability estimation was proposed using environmental noise classification for speech enhancement.A relevant noise estimation approach,known as the speech presence uncertainty tracking method,requires seeking the "a priori" probability of speech absence that is derived by applying microphone input signal and the noise signal based on the estimated value of the "a posteriori" signal-to-noise ratio(SNR).To overcome this problem,first,the optimal values in terms of the perceived speech quality of a variety of noise types are ***,the estimated optimal values are assigned according to the determined noise type which is classified by a real-time noise classification algorithm based on the Gaussian mixture model(GMM).The proposed algorithm estimates the speech absence probability using a noise classification algorithm which is based on GMM to apply the optimal parameter of each noise type,unlike the conventional approach which uses a fixed threshold and smoothing *** performance of the proposed method was evaluated by objective tests,such as the perceptual evaluation of speech quality(PESQ) and composite *** was then evaluated by a subjective test,namely,mean opinion scores(MOS) under various noise *** proposed method show better results than existing methods.

关键词： speech enhancement soft decision speech absence probability Gaussian mixture model (GMM)

Mssbauer spectra of MnFe_(2-2x)Al_(2x)O_4(0≤x≤0.4) ferrites

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Journal of Central South University 2010年第6期17卷 1129-1132页

作者： BATOO K M KUMAR S PRAKASH R ALIMUDDIN SONG J I CHUNG H JEONG H KOO B H LEE C G King Abdullah Institute for Nanotechnology King Saud UniversityRiyadh 11451Saudi Arabia School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and BK21 Eco-Friendly Heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.

关键词： ferrites hyperfine interactions Moessbauer spectroscopy isomer shift

Distributed Coordinator Election Scheme for QoS Support and Seamless Connectivity in WPANs

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Journal of Computer Science & Technology 2009年第6期24卷 1138-1148页

作者： Soon-Gyu Jeong Sang-Jo Yoo Graduate School of Information Technology & Telecommunications Inha University

Wireless personal area networks （WPANs） are formed in a relatively small area, and coordinator that serves as a central control device plays an important role in the operation and organization of a piconet. Typical applications of WPANs include home automation systems, security systems and health monitoring systems. In these types of systems, guaranteeing seamless connectivity is very important, and communications cannot take place when the coordinator malfunctions. Thus, in the case of a breakdown, it is necessary to elect a new coordinator as soon as possible. For this reason, a distributed coordinator election scheme （DCES） is proposed that considers not only QoS support but also network connectivity in an effort to avoid possible network partition. Simulation results show that the proposed scheme can elect a new coordinator while maintaining QoS and guaranteeing connectivity for a limited period.

关键词： QoS seamless connectivity leader election piconet coordinator (PNC) wireless personal area network (WPAN)

Microstructure of fast tool servo machining on copper alloy

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中国有色金属学会会刊：英文版 2012年第S3期22卷 820-824页

作者： Hong LU Soo-chang CHOI Sang-min LEE Deug-woo LEE Department of Nano Fusion Technology Pusan National University Korea Institute of Machinery & Materials Department of Nano Mechatronics Engineering Pusan National University

The development of the fast tool servo (FTS) for precision machining was *** micron machining performance of a piezoelectric-assisted FTS on copper alloy was *** results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the *** excessive driving frequency increases the formation of *** effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.

关键词： fast tool servo microstructure piezoelectric diamond machining copper alloy

A study on the interference effects for tidal current power rotors

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Science China(Technological Sciences) 2010年第11期53卷 3094-3101页

作者： Chul-Hee JO Kang-Hee LEE Jin-Young YIM Department of Naval Architecture & Ocean Engineering Inha University

Due to global warming, the need to secure an alternative resource has become more important nationally. With the high tidal range of up to 9.7 m on the west coast of Korea, numerous tidal current projects are being planned and constructed. To extract a significant quantity of power, a tidal current farm with a multi-arrangement is necessary in the ocean. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. The power generation is strongly dependent on the size of the rotor and the incoming flow velocity. However, the interactions between devices also contribute significantly to the total power capacity. Therefore, rotor performance considering the interaction problems needs to be investigated for generating maximum power in a specific field. This paper documents a performance study of devices considering the interference between rotating rotors with axial, transverse and diagonal arrangements.

关键词： TCP (tidal current power) renewable energy interference effect rotor CWC (circulation water channel) CFD (computational fluid dynamics)