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Frontiers of Optoelectronics 2010年第1期3卷 61-66页

作者： G.BRAMBILLA y.jung F.RENNA Optoelectronics Research Centre University of Southampton

The modified “flame brushing” technique has been used to manufacture microwires and nanowires from both silica and compound glasses. In this paper, the properties of the wires manufactured by this technique are pres... 详细信息

关键词： optical micro- and nano-fibers (OMNF) microwire nanowire flame brushing

Intermodal frequency generation in silicon-rich silicon nitride waveguides

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Photonics Research 2019年第6期7卷 615-621页

作者： C.LACAVA T.DOMINGUEZ BUCIO A.Z.KHOKHAR P.HORAK y.jung F.y.GARDES D.J.RICHARDSON P.PETROPOULOS F.PARMIGIANI Optoelectronics Research Centre University of SouthamptonS0171BJ Southampton UK Currently at Microsoft Research UK CB1 2FB Cambridge UK

Dispersion engineering in optical waveguides allows applications relying on the precise control of phase matching conditions to be implemented. Although extremely effective over relatively narrow band spectral regions,dispersion control becomes increasingly challenging as the bandwidth of the process of interest *** matching can also be achieved by exploiting the propagation characteristics of waves exciting different spatial modes of the same waveguide. Phase matching control in this case relies on achieving very similar propagation characteristics across two, and even more, waveguide modes over the wavelengths of interest, which may be rather far from one another. We demonstrate here that broadband(>40 nm) four-wave mixing can be achieved between pump waves and a signal located in different bands of the communications spectrum(separated by50 nm) by exploiting interband nonlinearities. Our demonstration is carried out in the silicon-rich silicon nitride material platform, which allows flexible device engineering, allowing for strong effective nonlinearity at telecommunications wavelengths without deleterious nonlinear-loss effects.

关键词： Intermodal frequency silicon-rich silicon nitride waveguides

Relation between etching profile and voltage-current shape of sintered SiC etching by atmospheric pressure plasma

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Plasma Science and Technology 2019年第4期21卷 137-144页

作者： D C SEOK S R yOO K I LEE y S CHOI y H jung Plasma Technology Research Center National Fusion Research InstituteGunsan City 54004Republic of Korea

Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma *** stable filament plasma was generated and could be used for SiC *** the processing gas(NF3)mixing rate increased,the width and depth of the etching profile became narrower and *** differentiated V-Q Lissajous method was used for measuring the capacitances(Ceq)of the electrode after the plasma turned *** width of the etching profile was proportional to *** the current peak value/smx of the substrate current in creased,the volume removal rate of SiC *** etch depth was proportional to the ratio of/smx to ***,because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity,the etching profile was ***,in high NF3 mixing process,the etching profile became stable and deeper.

关键词： dielectric barrier discharge silicon carbide plasma etching、filament discharge,surface charge

Isolation of intact bacteria from blood by selective cell lysis in a microfluidic porous silica monolith

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Microsystems & Nanoengineering 2019年第1期5卷 418-428页

作者： jung y.Han Michael Wiederoder Don L.DeVoe Department of Mechanical Engineering University of MarylandCollege ParkMD 20742USA Department of Chemical and Biomolecular Engineering University of MarylandCollege ParkMD 20742USA Fischell Department of Bioengineering University of MarylandCollege ParkMD 20742USA

Rapid and efficient isolation of bacteria from complex biological matrices is necessary for effective pathogen identification in emerging single-cell ***,we demonstrate the isolation of intact and viable bacteria from whole blood through the selective lysis of blood cells during flow through a porous silica *** mechanical hemolysis is achieved while providing passage of intact and viable bacteria through the monoliths,allowing size-based isolation of bacteria to be performed following selective lysis.A process for synthesizing large quantities of discrete capillary-bound monolith elements and millimeter-scale monolith bricks is described,together with the seamless integration of individual monoliths into microfluidic *** impact of monolith morphology,geometry,and flow conditions on cell lysis is explored,and flow regimes are identified wherein robust selective blood cell lysis and intact bacteria passage are achieved for multiple gram-negative and gram-positive *** technique is shown to enable rapid sample preparation and bacteria analysis by single-cell Raman *** selective lysis technique presents a unique sample preparation step supporting rapid and culture-free analysis of bacteria for the point of care.

关键词： silica porous quantities

Denitrification Rates and Their Controlling Factors in Streams of the Han River Basin with Different Land-Use Patterns

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Pedosphere 2014年第4期24卷 516-528页

作者： S.P.jung y.J.KIM H.KANG School of Civil and Environmental Engineering Yonsei UniversitySeoul 120-749(Korea) River and Coastal Research Division Korea Institute of Construction TechnologyGoyang 211-712(Korea)

Land-use patterns can affect various nutrient cycles in stream ecosystems, but little information is available about the effects of urban development on denitrification processes at the watershed scale. In the presented study, we investigated the controlling factors of denitrification rates within the streams of the Han River Basin, Korea, with different land-use patterns, in order to enhance the effectiveness of water resource management strategies. Ten watersheds were classified into three land-use patterns （forest, agriculture and urban） using satellite images and geographic information system techniques, and in-situ denitrification rates were determined using an acetylene blocking method. Additionally, sediment samples were collected from each stream to analyze denitrifier communities and abundance using molecular approaches. In-situ denitrification rates were found to be in the order of agricultural streams （289.6 mg N20-N m-2 d-1）〉 urban streams （157.0 mg N20-N m-2 d-1）〉 forested streams （41.9 mg N20-N m-2 d-l）. In contrast, the average quantity of denitrifying genes was the lowest in the urban streams. Genetic diversity of denitrifying genes was not affected by watershed land-use pattern, but exhibited stream-dependent pattern. More significance factors were involved in denitrification in the sites with higher denitrification rates. Multiple linear regression analysis revealed that clay, dissolved organic carbon and water contents were the main factors controlling denitrification rate in the agricultural streams, while dissolved organic carbon was the main controlling factor in the urban streams. In contrast, temperature appeared to be the main controlling factor in the forested streams.

关键词： denitrifier communities denitrifying genes nutrient cycle stream ecosystem

State estimation for neural neutral-type networks with mixed time-varying delays and Markovian jumping parameters

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Chinese Physics B 2012年第10期21卷 29-37页

作者： S.Lakshmanan Ju H.Park H.y.jung P.Balasubramaniam Department of Information and Communication Engineering/Electrical Engineering Yeungnam University214-1 Dae-DongKyongsan 712-749Republic of Korea Department of Mathematics Gandhigram Rural Institute-Deemed UniversityGandhigram - 624 302TamilnaduIndia

This paper is concerned with a delay-dependent state estimator for neutral-type neural networks with mixed timevarying delays and Markovian jumping *** addressed neural networks have a finite number of modes,and the modes may jump from one to another according to a Markov *** construction of a suitable Lyapunov-Krasovskii functional,a delay-dependent condition is developed to estimate the neuron states through available output measurements such that the estimation error system is globally asymptotically stable in a mean *** criterion is formulated in terms of a set of linear matrix inequalities（LMIs）,which can be checked efficiently by use of some standard numerical packages.

关键词： neural networks state estimation neutral delay Markovian jumping parameters

Design Features and Commissioning of the Versatile Experiment Spherical Torus (VEST) at Seoul National University

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Plasma Science and Technology 2013年第3期15卷 244-251页

作者： K.J.CHUNG y.H.AN B.K.jung H.y.LEE C.SUNG y.S.NA T.S.HAHM y.S.HWANG Department of Nuclear Engineering Seoul National University

A new spherical torus called VEST （Versatile Experiment Spherical Torus） is designed, constructed and successfully commissioned at Seoul National University. A unique design feature of the VEST is two partial solenoid coils installed at both vertical ends of a center stack, which can provide sufficient magnetic fluxes to initiate tokamak plasmas while keeping a low aspect ratio configuration in the central region. According to initial double null merging start-up scenario using the partial solenoid coils, apprdpriate p6wer supplies for driving a toroidal field coil, outer poloidal field coils, and the partial solenoid Coils are fabricated and successfully commissioned. For reliable start-up, a pre-ionization system with two cost-effective homemade magnetron power supplies is also prepared. In addition, magnetic and spectroscopic diagnostics with appropriate data acquisition and control systems are well prepared for initial operation of the device. The VEST is ready for tokamak plasma operation by completing and commissioning most of the designed components.

关键词： spherical torus partial solenoids double null merging start-up

Study on durability of Pt supported on graphitized carbon under simulated start-up/shut-down conditions for polymer electrolyte membrane fuel cells

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Journal of Energy Chemistry 2018年第1期27卷 326-334页

作者： Won Suk jung Department of Chemical Engineering University of South CarolinaColumbiaSC 29208USA

The primary issue for the commercialization of proton exchange membrane fuel cell（PEMFC） is the carbon corrosion of support under start-up/shut-down conditions. In this study, we employ the nanostructured graphitized carbon induced by heat-treatment. The degree of graphitization starts to increase between 900 and 1300 ℃ as evidenced by the change of specific surface area, interlayer spacing, and ID/IG value. Pt nanoparticles are deposited on fresh carbon black（Pt/CB） and carbon heat-treated at 1700 ℃（Pt/HCB17） with similar particle size and distribution. Electrochemical characterization demonstrates that the Pt/HCB17 shows higher activity than the Pt/CB due to the inefficient microporous structure of amorphous carbon for the oxygen reduction reaction. An accelerating potential cycle between 1.0 and 1.5 V for the carbon corrosion is applied to examine durability at a single cell under the practical start-up/shutdown conditions. The Pt/HCB17 catalyst shows remarkable durability after 3000 potential cycles. The Pt/HCB17 catalyst exhibits a peak power density gain of 3%, while the Pt/CB catalyst shows 65% loss of the initial peak power density. As well, electrochemical surface area and mass activity of Pt/HCB17 catalyst are even more stable than those of the Pt/CB catalyst. Consequently, the high degree of graphitization is essential for the durability of fuel cells in practical start-up/shut-down conditions due to enhancing the strong interaction of Pt and π-bonds in graphitized carbon.

关键词： Polymer electrolyte membrane fuel ceils Membrane electrolyte assembly Carbon corrosion Start-up/shut-down Durability

Tolerating Permanent State Transition Faults in Asynchronous Sequential Machines

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Journal of Computer Science & Technology 2016年第5期31卷 1028-1037页

作者： jung-Min yang School of Electronics Engineering Kyungpook National University Daegu 41566 Korea

Corrective control theory lays a novel foundation for the fault-tolerant control of asynchronous sequential machines. In this paper, we present a corrective control scheme for tolerating permanent state transition faults in the dynamics of asynchronous sequential machines. By a fault occurrence, the asynchronous machine may be stuck at a faulty state, not responding to the external input. We analyze the detectability of the considered faults and present the necessary and sufficient condition for the existence of a controller that overcomes any permanent transition faults. Fault tolerance is realized by using potential reachability and asynchronous mechanisms in the machine. A case study on an asynchronous counter is provided to illustrate the proposed fault detection and tolerance scheme.

关键词： asynchronous sequential machine corrective control permanent fault fault tolerance

Next High Performance and Low Power Flash Memory Package Structure

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Journal of Computer Science & Technology 2007年第4期22卷 515-520页

作者： jung-Hoon Lee ERI Control Instrumentation EngineeringGyeongSang National UniversityJinju660-701Korea

In general, NAND flash memory has advantages in low power consumption, storage capacity, and fast erase/write performance in contrast to NOR flash. But, main drawback of the NAND flash memory is the slow access time for random read operations. Therefore, we proposed the new NAND flash memory package for overcoming this major drawback. We present a high performance and low power NAND flash memory system with a dual cache memory. The proposed NAND flash package consists of two parts, i.e., an NAND flash memory module, and a dual cache module. The new NAND flash memory system can achieve dramatically higher performance and lower power consumption compared with any conventionM NAND-type flash memory module. Our results show that the proposed system can reduce about 78% of write operations into the flash memory cell and about 70% of read operations from the flash memory cell by using only additional 3KB cache space. This value represents high potential to achieve low power consumption and high performance gain.

关键词： flash memory NAND-type NOR-type memory localities buffer or cache memory