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The transport of cobalt ion in a continuous electrodeionization (CEDI) system was investigated in terms of electrochemical properties of ion exchange textile. The porous plug model and an extended Nernst‐Plank equation were applied to describe the transport of Co2+ through an ion exchange textile. The transport characteristics of Co2+ during CEDI operation suggested the transport mechanism was due mainly to the increased current induced by the high conductivity in the ion exchange textile, not accelerated ionic mobility. This study suggested the important parameter for the high performance of the CEDI system is the conductivity of the ion exchange media.

An RO-CEDI (Reverse osmosis-continuous electrodeionization) hybrid process was investigated to pro- duce high purity water. The RO system, with an effective membrane area of 1.1 m 2 , was operated using tap water with conductivity of 64 µs·cm −1 , and the CEDI system experiments were carried out in a cell-pair stack consisting of 3 com- partments. During the parametric study of the RO-CEDI hybrid system, the optimal operating conditions were deter- mined based on the water purity. The electrical resistivity and water dissociation of the ion exchange resins and ion exchange membrane were verified as the key mechanisms of the CEDI system in the water purification. The produced water met the quality requirements as a make-up water in a nuclear power plant with a resistivity of 10-16.7 MΩ·cm.

We have investigated the optical response of periodic arrays of metallic (gold) nanoparticles composed of a pair of particles on each lattice site. By varying the interparticle separation within the pairs from dielectric proximity to conductive contact on a nanometer scale, we observe an abrupt, large renormalization as well as a splitting of the surface plasmon polariton energy. These spectral anomalies are ascribed to a transition whereupon the interparticle dipole−dipole interaction is shunted and the plasmon polaritons exhibit multipolar behavior, including a very high local concentration of electromagnetic energy in the vicinity of their conductive contact.

This study investigated the production of high-purity water in the primary coolant of a nuclear power plant via the continuous electrodeionization (CEDI) process, using ion exchange resins as ion-conducting media between ion exchange membranes. The effectiveness of this method was examined with respect to the removal of heavy metals. The study was carried out on a laboratory scale with an effective area of 20 cm(2). The CEDI system was operated with a layered bed of cation exchange resins, anion exchange resins, and mixed-bed ion exchange resins. The stack configuration was designed to prevent a reaction between metal ions and hydroxide ions. The CEDI operation with the layered bed removed more than 99% of the ions at 30% of the current efficiency. The results showed that, with an inlet conductivity of 40 microScm(-1), a linear velocity of 4.17 cms(-1), and an applied current density of 17 mAcm(-2), the CEDI process yielded an outlet conductivity of 0.5 microScm(-1), thereby preventing the precipitation of metal ions. This study therefore successfully demonstrated the feasibility of the CEDI operation for the removal of heavy metals at a very low concentration.

A magnetic filter - continuous electrodeionization (CEDI) hybrid separation system was investigated for the purification of the primary coolant in a nuclear power plant. A magnetic filter system with a 3000 Gauss magnetic field and a CEDI system with a cell consisting of 3 compartments were used for the removal of magnetite and nickel ions, respectively. The hybrid separation system achieved removal rates of 98% for magnetite and 99% for the nickel ions demonstrating its feasibility for the purification of primary coolant.

Ion-exchange textiles (IETs) suitable for use in continuous electrodeionization (CEDI) stacks were prepared using the ultraviolet (UV)-induced grafting of acrylic acid and sodium styrene sulfonate for cation-exchange textiles, or 2-hydroxyethyl methacrylate and vinylbenzyl trimethyl ammonium chloride for anion-exchange textiles, onto nonwoven polypropylene fabric using benzophenone as photoinitiator. Although the ion-exchange capacity (2.2 meq g−1) of the prepared strong acid cation-exchange textile was lower than that of IRN77 strong acid cation-exchange resin (4.2 meq g−1), the overall rate constant of IET was very high due to its low crosslinking and high specific surface area. There was no significant difference between the two different media in terms of the Co(II) removal rate. Furthermore, the current efficiency for IETs was higher than that of IRN77 cation-exchange resin during a CEDI operation, with efficiencies of 60% and 20%, respectively. The IET also showed the faster exchange kinetics. Therefore, IETs prepared in this study proved to have desirable ion-conducting characteristics within the CEDI systems. Also this study revealed that the primary removal mechanism in CEDI is the transport of ions through a medium and not the ionic capacity of a medium. Copyright © 2004 Society of Chemical Industry

The distributions, densities and energies of defects near InGaN/GaN quantum wells in blue light-emitting diodes were simultaneously determined by utilizing capacitance–voltage (C–V) measurements. By combining the modulation frequency dependency, temperature dependency and C–V depth profiling with additional laser illumination, the densities and the locations of the defective layers could be determined. The relative defect densities of the devices were directly compared by monitoring the magnitude of the frequency dependence. This frequency dependency varies distinctly as the sample temperature changes. The activation energies of defects are then determined by analyzing the frequency dependency of C–V with temperature. We found that three different defects states were formed in a low-temperature-grown un-doped GaN (LT-GaN) layer inserted under the active layer. The activation energies of those defects were determined to be 3.96, 12.1 and 45.9 meV. The formation of additional defects states in the active layers induced by the insertion of LT-GaN layer was also observed.

Colloidal quantum dots (CQDs) are promising light harvesting materials for realization of solution processible, highly efficient multipurpose photovoltaics (PVs). Here, PbS CQD solar cells are reported with improved certified power conversion efficiency performance of 10.4% by simply controlling protic solvents (alcohols) in ligand exchange process. With shorter chain alcohols, the mobility of charge carriers is an order-of-magnitude improved due to the enhanced interparticle coupling; on the other hand, excessive removal of passivating ligands by very protic solvent, methanol (MeOH) induced undesirable traps on CQD surface. Consequently, it has been found that high performance CQD PVs require a solvent engineering for balance between native leaving ligands with incoming ligands during ligand exchange process for well-controlled surfaces of CQDs and enhanced carrier concentration of conductive CQD films.

GaN-based LEDs often develop unintended strain, due to the lattice and thermal expansion mismatch between the sapphire substrate and GaN layers. This residual compressive strain in GaN overlayers can cause a number of critical effects, such as wafer bowing, threading dislocation generation that impact the overall properties of the epilayers, and the resulting device performance. Raman spectroscopy is known to be a useful technique for measuring strain analysis by monitoring the energy position of the E2 (high) mode. However, the local strain of a specific area cannot be obtained by conventional Raman spectroscopy since the excitation laser in the usual case is transparent and scattered throughout the whole LED structure. As a result, only the average strain of the entire structure is generally measured. We successfully analyzed the depth dependent strain distribution by applying the SERS technique and careful sample manupulation, to produce a truncated structure. Our results showed that the strain in the undoped GaN buffer layers and the n-GaN layer gradually decreased up to the quantum well region, as the thickness increased, while the strain saturated in the active and p-GaN layers. The depth depndent strain was also quantified using our analysis.

The fast degradation of lead selenide (PbSe) nanocrystal quantum dots (NQDs) in ambient conditions impedes widespread deployment of the highly excitonic, thus versatile, colloidal NQDs. Here we report a simple in situ post-synthetic halide salt treatment that results in size-independent air stability of PbSe NQDs without significantly altering their optoelectronic characteristics. From TEM, NMR, and XPS results and DFT calculations, we propose that the unprecedented size-independent air stability of the PbSe NQDs can be attributed to the successful passivation of under-coordinated PbSe(100) facets with atomically thin PbX2 (X = Cl, Br, I) adlayers. Conductive films made of halide-treated ultrastable PbSe NQDs exhibit markedly improved air stability and behave as an n-type channel in a field-effect transistor. Our simple in situ wet-chemical passivation scheme will enable broader utilization of PbSe NQDs in ambient conditions in many optoelectronic applications.

The strain and piezoelectric fields in InGaN blue light-emitting diodes on a GaN layer, which is grown on a planar sapphire substrate or patterned sapphire substrates (PSSs), such as a microsized PSS and a nanosized PSS (NPSS), are investigated by micro-Raman spectroscopy and electroreflectance (ER) spectroscopy. The obtained piezoelectric field in InGaN multiple quantum wells (QWs) grown on the planar substrate is 0.83 MV/cm, and it is 0.70 MV/cm for the case of the NPSS. These results are attributed to the fact that the GaN layers on the PSSs have a smaller residual strain compared to that on the planar sapphire, and thus, strain reduction in the GaN layer can reduce the piezoelectric field in the InGaN QWs grown on top of it.

We investigated the effects of a strain-control layer on piezoelectric fields and indium incorporation in blue-emitting InGaN/GaN quantum wells (QWs) using reverse-biased electroreflectance spectroscopy. With this technique, we could determine the change in both indium incorporation and the piezoelectric field by the inserted buffer layer. We compared two test samples, which have identical structures except for the insertion of an additional InGaN layer at the bottom of the blue-QW. The magnitude of the piezoelectric fields in the QWs with the added layer was significantly smaller even with a slightly higher indium composition. The result shows that the strain in the QW is partially released and can be controlled quantitatively by the strain-control layer underneath. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, we construct an oblique reflecting switched diffusion process and give the Skorohod representation for this process by using the Dirichlet space theory. We show the tightness property for a sequence of these processes. To do this, we extend the Lyons–Zheng decomposition theorem to the oblique reflecting switched diffusion process

Transportation safety is one of the most important applications for vehicular ad-hoc networks based on IEEE 802.11p. When a vehicle is in an emergency condition, a safety-related message is transmitted to the neighboring vehicles and infrastructures. Vehicles and infrastructures are exchanging periodic messages on the vehicle position, traffic information to provide various services. When the traffic load is very high, the emergency message cannot be delivered immediately. To overcome this situation, a priority based transmission scheme is considered to guarantee the transmission of the emergency message. We analyze the performance of vehicular communication networks in two perspectives. Firstly, an analytical Markov-chain model for vehicle-to-vehicle (V2V) ad-hoc communication networks is proposed for broadcasting messages with priority based on IEEE 802.11p. Secondly, an analytic Queuing model for vehicular communication networks are proposed to evaluate the network performance for dealing with safety and non-safety messages from the point of the infrastructure.

We propose and demonstrate to derive the Auger recombination coefficient by fitting efficiency–current and carrier lifetime–current curves simultaneously, which can minimize the uncertainty of fitting results. The obtained Auger recombination coefficient is cm6s−1 in the present sample, which contributes slightly to efficiency droop effect.

The water transport in a gas diffusion layer (GDL) has been investigated using two-dimensional lattice Boltzmann (LB) simulation. The LB model is developed to simulate the dynamic behavior of liquid water and enables to visualize the water-invasion process through micro-pores in GDL. To investigate the effect of rib structure on water invasion process in GDL, two different cases (i.e., with and without rib structure) are compared. The numerical model is verified by the comparison of the flow permeabilities in GDL. The validation result indicates that the LB model can properly predict the permeability of GDL and enables to simulate the water transport behavior in the GDL. The reconstruction of GDL is established by randomly placing the particles in GDL and ignoring the GDL deformation due to clamping force. The results of LB simulation confirm that the liquid water transport inside GDL is strongly governed by capillary force and the rib structure greatly impacts on the water transport behavior. The rib structure influences on the location of water breakthrough by comparing the simulation results of two different cases. This is due to the higher resistance force underneath the rib, resulting in the change of flow path which preferentially selects the lower resistance force. The water saturation level under the channel is higher than that under the rib caused by the suppression of growth of water cluster. After water breakthrough, the liquid water distribution under the channel has little change, whereas that under the rib keeps stretching for a while. The result indicates that a careful control of rib structure would enhance the water removal from the GDL. Therefore further studies for the optimum design of rib structure are needed. In an operating PEMFCs, the mechanism of water transport and wetting characteristics play an important role on flooding behavior. Therefore the results of the present study would contribute to the novel design for better water removal and flooding alleviation from the GDL.

In this work, aggregation and breakage of Li-ion precursor in Taylor-reactor are studied for various simulation condition, i.e., agitation rate, particle property, and reactor direction. The mean particle size and distribution is important to electrochemical performance of cathode materials. The population balance equation (PBE) is solved for coupling between particle interaction and fluid dynamic. The quadrature method of moments (QMOM) is implemented in a commercial computational fluid dynamics (CFD) code. Sum of three aggregation kernels, such as turbulent, Brownian, and Stokes aggregation, is considered for the calculation. [1] Breakage kernel is a combination of power-law kernel and various daughter distribution functions. Collision efficiency is assumed to be equal and the precursor is considered as spherical particle. Three-dimensional analysis is implemented and the simulation results are compared with experimental data. [1] L. Claudotte, N. Rimbert, P. Gardin, M. Simonnet, J. Lehmann, and B. Oesterle, AIChE J., Vol.56, No.9, pp. 2347-2355 (2010)

Self-assembled ZnSe/ZnS quantum dots (QDs) have been grown in the Stranski–Krastanov (S–K) mode using a metalorganic chemical vapor deposition technique under the atomic-layer epitaxy mode. Atomic-force-microscopy measurements on the uncapped ZnSe/ZnS QDs reveal that lens-shaped ZnSe QDs are formed after 1–2 monolayer ZnSe is deposited. The ZnSe QDs are estimated 1–2 nm in height and 25–35 nm in radius. The temperature-dependent behavior of confined carriers in the ZnSe QDs has been investigated through photoluminescence (PL) measurements. PL spectra show a substantial PL linewidth narrowing accompanied by a large redshift of the emission peak energy with increasing temperature. This unusual temperature-dependent behavior is interpreted as the dot-to-dot carrier transfer through the wetting layer, which is common to QDs grown in the S–K mode.

We apply an optical probing technique on AlGaN/GaN field-effect transistors to demonstrate that coherent gigahertz phonons are generated copiously under large signal operation. The phonon generation originates from time varying electron screening of the piezoelectric polarization fields in the active region, and may provide a nondiffusive means of energy dissipation for high power devices.

Synthesis of silver nanoplates was studied in the modified polyol method, where the nucleation and seed stage occurred in a poly(ethylene glycol) (PEG)–water mixture solution, and the growth stage happened in the PEG environment. The morphological evolution of nanoplates was characterized using UV, SEM, and TEM. Interestingly, plane nanostructures with unusual jagged edges were finally formed in our modified polyol method. Using TEM, we observed the medium state of fusion between two nanoplates, resulting in generating unusual jagged edges. Therefore, a novel two-dimensional oriented attachment occurred in our modified polyol method, which involves smaller nanoplates as the building blocks. Further control experiments showed that the presence of water could break this kinetic preferred reactivity, leading to the formation of nanoparticles.

A simple and mass productive extrusion technique was applied to fabricate anode-supported micro-tubular solid oxide fuel cells (SOFCs). A standard NiO/8YSZ (Nickel oxide/8 mol % yttria stabilized zirconia) cermets anode, 8 YSZ electrolyte, and LSM (Lanthanum strontium manganite) cathode were used as the materials components. SEM (secondary electron microscopy) images indicated vacuum infiltration method successfully generated the thin electrolyte layer (10∼15 μm) with a structurally effective three phase boundaries. Fabricated unit cell showed the open circuit voltage of 1.12 V without any fuel leaking problems. Electrochemical tests showed a maximum power density up to 0.30 W/cm2 at 800 °C, implying the excellent performance as micro-tubular SOFCs. This study verified that the extrusion aided by vacuum infiltration process could be a promising technique for mass production of microtubualr SOFCs.Copyright © 2008 by ASME

A communication system is developed for ubiquitous - transportation sensor network (u-TSN). The developed system is used for inter-vehicle and vehicle-to-road side unit communications. The communication module is based on the IEEE 802.11a/g standard. The maximum throughput of the communication module is about 10 to 15 Mbps depending on the distance and moving speed.

We performed surface-plasmon enhanced Raman scattering (SERS) studies of a DNA monolayer on chemically modified Au nanoparticle arrays. Drastic enhancement of Raman signal from DNA molecules was observed on the optimized templates that were prepared by using electron-beam lithography followed by chemical modification. We observed that Raman signal of DNA molecules was enhanced when the surface plasmons in the closely-spaced Au nanoparticles were resonantly excited. Our results suggest that the artificial generation of spatially controlled hot spots for SERS can be achieved by this technique.

It is usually accepted that the doped ceria buffer layer is needed between the conventional yttria-stabilized zirconia (YSZ) electrolytes and the Fe and Co containing cathode materials such as (La,Sr)(Co,Fe)O3-δ (LSCF) to improve the cell performance and to prevent unwanted chemical reactions between them. In this study, the effect of the sintering temperature, cobalt doping amount, and the starting powders of GDC (Gadolinium Doped Ceria) layer were investigated. The cell testing result indicated that it would be desirable to decide the sintering temperature of the GDC layer less than 1250°C to minimize the effect of the solid solutions based on (Zr, Ce)O2 . Furthermore, 5 days operations of the button cell with cobalt doped GDC layer showed the increased ohmic and polarization resistance, indicating the cobalt segregation from the GDC layer during the long term operation.Copyright © 2010 by ASME

In this study, a thin (less than 1 micrometer) interlayer of gadolinia doped ceria (GDC) was applied by aerosol deposition (AD) process between YSZ electrolyte and LSCF-GDC composite cathode. The GDC interlayer was co-fired with the cathode without an additional heat treatment step. Performance of the cells with the GDC layer was evaluated with small button type cells. The results show that the GDC layer was dense enough to successfully prevent the formation of SrZrO3 layer after cathode heat treatments under 1100°C. Electrochemical performance of the cells largely depended on the sintering temperatures. Maximum power densities were 1.0 ± 0.1 W/cm2 at 750°C after sintering at the temperatures between 1000°C and 1060°C. Through SEM and TEM study, solid solution layer at the interface of GDC layer and YSZ layer was found in the specimen after sintering at 1000°C and SrZrO3 layers on both sides of the GDC layer after heat treatment at 1100°C. These layers contributed to the poor performance of the cells sintered at over 1080°C. Therefore, the temperatures for cathode sintering have to be precisely controlled to get the best performance. AD process requires week vacuum and takes only couple minutes to finish deposition. This presentation also shows scaling up the ADM process to 320 mm × 220 mm planar cells for dozens kW stack application at the Research Institute of Industrial Science and Technology (RIST) in Korea. Long term operation tests for the large cells are now on process.Copyright © 2010 by ASME

Diels-Alder reaction of cyclic sugar dienophiles with cyclopentadiene and cyclohexadiene occurred in totally exo - and face-selective manner to afford single stereoisomers, one of which wa tranformed into a highly substituted cyclopentane.

Periodic Au nanoparticle arrays, fabricated using electron beam lithography, have been modified by chemical reaction in solutions having various concentrations of a reducing agent. As the nanoparticles enlarge due to the formation of additional Au nanolumps on the surface, both the position and intensity of plasmon absorbance of Au nanoparticle arrays change in proportion to the concentration of the reducing agent. Moreover, the plasmon absorbance is split into dipole and quadrupole modes as conductive connections form between the particles. Our results demonstrate that the changes in both the position and intensity of plasmon absorbance can be employed together as complementary readout values of nanosensors.

Trichuris trichiura, commonly referred to as a whipworm, has a worldwide distribution, particularly among countries with warm, humid climates. In Korea, trichuriasis was a highly prevalent soil-transmitted helminthiasis until the 1970s. However, the nationwide prevalence decreased to 0.02% in 2004 as a result of national control activities and improvement in the socioeconomic status of Koreans. Most infected individuals have no distinct symptoms, if lightly infected. The diagnosis is typically confirmed by detection of T. trichiura eggs on examination of a stool sample; few reports have described detection of the parasite during colonoscopy. Recently, we managed 4 patients with trichuriasis who were diagnosed by detection of the parasite on colonoscopy, and we reviewed the literature on the colonoscopic diagnosis of T. trichiura in Korea. We suggest that colonoscopy might be a useful diagnostic tool, especially when infected by only a few male worms with no eggs in the stool.

We investigated the effects of prestrained layers on piezoelectric fields and indium incorporation in blue-emitting InGaN/GaN quantum wells by using reverse-biased electroreflectance spectroscopy. We compared two sets of samples, which have identical structures except an insertion of an additional UV quantum well at the bottom of the blue-quantum well. Indium composition of quantum wells with the additional layer is larger than in the wells without the added layer. In contrast, the magnitude of the piezoelectric fields in the quantum wells with the added well is smaller even with higher In composition. The result shows that the strain in the quantum well is partially released and can be controlled by the insertion of the prestrained layer underneath.

A planar anode-supported electrolyte was fabricated using a tape casting method that involved a single step cofiring process. A standard NiO∕8YSZ cermet anode, 8mol% YSZ electrolyte, and a lanthanum strontium manganite cathode were used for the solid oxide fuel cell unit cell. A pressurized cofiring technique allows the creation of a thin layer of dense electrolyte about 10μm without warpage. The open circuit voltage of the unit cell indicated negligible fuel leakage through the electrolyte film due to the dense and crack-free electrolyte layer. An electrochemical test of the unit cell showed a maximum power density up to 0.173W∕cm2 at 900°C. Approximated electrochemical properties, e.g., activation energy, Ohmic resistance, and exchange current density, indicated that the cell performance was significantly influenced by the electrode properties of the unit cell.

A simple and mass productive extrusion technique was applied to fabricate anode-supported micro-tubular solid oxide fuel cells (SOFCs). A standard NiO/8YSZ (Nickel oxide/8 mol % yttria stabilized zirconia) cermets anode, 8 YSZ electrolyte, and LSM (Lanthanum strontium manganite) cathode were used as the materials components. SEM (secondary electron microscopy) images indicated vacuum infiltration method successfully generated the thin electrolyte layer (10∼15 μm) with a structurally effective three phase boundaries. Fabricated unit cell showed the open circuit voltage of 1.12 V without any fuel leaking problems. Electrochemical tests showed a maximum power density up to 0.30 W/cm2 at 800 °C, implying the excellent performance as micro-tubular SOFCs. This study verified that the extrusion aided by vacuum infiltration process could be a promising technique for mass production of microtubualr SOFCs.

Micro-tubular Solid Oxide Fuel Cells (SOFCs) are fabricated and tested for analysis of electrochemical properties. The impedance spectra from individual 1.8 mm diameter, 1.2 cm length micro-tubular SOFCs are obtained for the intermediate temperature range of 450–550°C. The micro-tubular SOFC used is anode supported, consisting of a NiO and Gd0.2 Ce0.8 O2−x (GDC) cermet anode, thin GDC electrolyte, and a La0.6 Sr0.4 Co0.2 Fe0.8 O3−y (LSCF) and GDC composite cathode. The impedance information gained at cell operating temperatures of 450, 500, and 550°C yielded power density losses of 0.8, 2.3, and 4.6% respectively. Within the operating temperature range of 450–550 °C, the ceria based 1.8 mm micro-tubular SOFCs were found to have a power densities ranging between 180–740 mW/cm2 .Copyright © 2008 by ASME

Micro tubular solid oxide fuel cells (SOFCs) have many desirable advantages compared to general SOFC. Recently, microtubualr SOFC are now studied to apply into APU system in a future generation vehicles. In this study, electrochemical and mechanical properties of the micro tubular SOFCs (less than 1 mm O.D.) have been characterized. Electrochemical characterization showed the excellent performance of MT SOFC with the power density of 1 W/cm2 at 600°C. Impedance measurement indicated that the contribution of contact resistance on the cell performance was still high and there were many possibilities to improve the cell performance. Mechanical test of the MT-SOFC using burst testing apparatus indicated the mechanical properties were mainly dependent on porosity and wall thickness, i.e. physical properties of anode support. This study examined the properties of micro-tubular SOFC using the novel characterization method for APU application.

Taylor reactor is composed of two co-axial cylinders where the outer one is stationary and the inner one is rotating. Recently, Taylor reactor is applied on the lithium ion battery to produce cathode material. In the reactor, complex chemical reactions and particle growth occur. The particle size and distribution have significant impact on the performance of cathode material. This study simulates inter-particle aggregation and breakage in Taylor reactor and predicts particle size and distribution. The simulated results are compared with experiment. The quadrature method of moments (QMOM) is implemented to solve a population balance equation (PBE). For the aggregation kernel, the sum of turbulence kernel and Brownian aggregation kernel is considered. The power-law kernel is taken as a breakage kernel. The mixture model is used to describe the interaction between continuous phase and dispersed phase. The effect of internal flow on the dispersed phase (i.e. particle) is investigated by changing rpm.

Nanoengineered fluorescent response is reported in semiconductor core-shell (CdSe/ZnS) quantum dots in proximity to the surface plasmon field of periodic silver nanoparticle arrays. Tuning the surface plasmon resonance to the quantum dot exciton emission band results in an /spl sim/50-fold enhancement of the fluorescence.

The strong coupling limit of cavity QED is reached when matter inserted inside a microcavity exchanges energy with the resonant mode of the cavity more rapidly than the combined rate at which light leaves the cavity and the matter wave function loses its phase information [1,2]. In this limit, the microcavity and matter form a composite quantum system with two new eigenstates that are superpositions of the initial uncoupled states, with new eigenenergies separated in energy by the Rabi splitting. The matter component of the coupled system can be a gas of atoms trapped inside the cavity [3], a superconducting qubit [4], or a solid state thin film containing excitons, in the form of an inorganic quantum well [5], quantum dot [6,7], or organic material [8], in which case the superposition states are referred to as exciton polaritons. Applications of strong coupling in atomic and semiconductor systems have led to one-atom zero threshold lasers [9], high gain polariton parametric amplifiers [10], and predictions that strong coupling may play a key role in future quantum information processors [11]. These experiments have all relied on optical pumping. Here we demonstrate electrically pumped exciton-polariton emission, the first device in which strongly coupled states of light and matter are electrically excited. The matter component of our device is a 6 � 1n mthick film of J aggregated dye. The film consists of 4 bilayers [12] of the cationic polyelectrolyte PDAC (poly diallyldimethylammonium chloride) and J aggregates of the anionic cyanine dye TDBC (5,6-dichloro-2-[3-[5,6-dichloro-1-ethyl-3-(3-sulfopropyl)-2(3H)-benzimidazolidene]-1-propenyl]-1-ethyl-3-(3-sulfopropyl) benzimidazolium hydroxide, inner salt, sodium salt), molecular structures shown in Fig. 1(a). The J aggregates are crystallites of dye in which the transition dipoles of the constituent molecules strongly couple to form a collective narrow linewidth optical transition possessing oscillator strength derived from all the aggregated monomers [13]. The bilayer films contain a high density of J aggregated TDBC and therefore have a very large peak absorption

In this paper, multi-band orthogonal frequency division multiplexing (MB-OFDM) system is analyzed as a strong candidate for wireless personal area network (WPAN) standard. MB-OFDM system provides the information data rate from 53.3 Mbps to 480 Mbps according to the used bandwidth. Also, the frequency/time-domain spreading schemes supply the frequency diversity gain but they decrease the transmission efficiency per unit time. To compensate this problem, the transmit diversity scheme is proposed where a symbol is repeatedly transmitted at the space domain. The bit error rate (BER) performance of the proposed system is confirmed by simulation

Exciton-polariton dynamics are studied in organic semiconductor microcavities operating in the strongly coupled polariton regime, with thin films of cyanine J-aggregates sandwiched between low-loss dielectric mirrors. The delocalized excitons are subject to polariton normal mode splittings which are modulated by near resonant femtosecond excitation pulses, while orientational disorder effects on the formation of polariton states play an important role in polariton dynamics.

The time-varying electron density in the channel of a microwave GaN/AlGaN FET gives raise to GHz coherent phonon generation due to the screening of the giant piezoelectric fields, which we measure optically. Such propagating nonthermal channels of energy release may be of relevance to future high power devices.

We have investigated the electromagnetic interaction of periodic arrays of metallic (gold) nanoparticles, composed of a pair of particles on each lattice site. By varying the interparticle separation from dielectric proximity to conductive contact on nm scale, we observe very large renormalization and splitting of the surface plasmon energy associated with an abrupt transition from the dipolar to a conductively coupled regime

Ultrafast nonlinear optical response is reported for Frenkel excitons in organic J-aggregate thin films, resonantly coupled to surface plasmons in gold nanoparticle arrays. We show that tuning the resonance wavelength of the surface plasmon of the arrays to the J-band of the surrounding cyanine dyes results in a strong enhancement of the optical nonlinearity

Nonlinear optical response is reported in organic semiconductor microcavities operating in the strongly coupled polariton regime, with thin films of cyanine J-aggregates sandwiched between low-loss dielectric mirrors. The delocalized excitons are subject to large polariton "Rabi" splittings and modulated by near resonant fsec excitation pulses.

Li(Ni0.6Mn0.2Co0.2)O2 (NMC622) cathode materials have been recognized as the next generation cathode materials due to its higher capacity and lower raw material cost than commercialized cathode materials such as NMC532. Thus, many industrial companies have been made every effort to commercialize and apply the NMC622 to lithium ion battery system such as energy storage system (ESS). However, production cost of NMC622 still has been recognized as expensive material to be applied in the industrial field and it becomes main issues to be overcome. CSTR (Continuous Stirred Tank Reactor) has been widely applied in the industrial field to produce the NMC622 precursor but it has initial long stabilization time as well as low production efficiency. This is caused by the original limitation of CSTR such as the low mass transfer rate and required complete mixing zone to stabilize the system. Thus, in this study, we suggest the novel reactor system that shows the higher mass transfer rate as well as higher production rate than those of CSTR. Developed novel reactor system uses the taylor-couette flows to induce higher mass transfer rate and production efficiency with uniform particle size distribution. In this study, we synthesized NMC622 using taylor-couette reactor to understand the function and mechanism of the operation. The effect of operating parameters, i.e. pH, operating rpm, and feed retention time, in the taylor-couette reactor, was investigated thoroughly to evaluate the feasibility to produce NMC622 precursor. Produced precursors are characterized using SEM, XRD, ICP, FIB, PSA. Then, cathode materials are prepared and tested using a galvanostatic intermittent titration method (GITT) to understand the electrochemical properties. This study verified that taylor couette reactor is feasible process to be applied to the commercial NMC622 production. Acknowledgement - This work was supported by the Korea Institute of Energy Technology Evaluation and Planning under the Energy Technology Development Program (20132020101750)

Li(Ni0.6Mn0.2Co0.2)O2 (NMC622) cathode materials have been recognized as the next generation cathode materials due to its higher capacity and lower raw material cost than commercialized cathode materials such as NMC532. Thus, many industrial companies have been made every effort to commercialize and apply the NMC622 to lithium ion battery system such as energy storage system (ESS). However, production cost of NMC622 still has been recognized as expensive material to be applied in the industrial field and it becomes main issues to be overcome. CSTR (Continuous Stirred Tank Reactor) has been widely applied in the industrial field to produce the NMC622 precursor but it has initial long stabilization time as well as low production efficiency. This is caused by the original limitation of CSTR such as the low mass transfer rate and required complete mixing zone to stabilize the system. Thus, in this study, we suggest the novel reactor system that shows the higher mass transfer rate as well as higher production rate than those of CSTR. Developed novel reactor system uses the taylor-couette flows to induce higher mass transfer rate and production efficiency with uniform particle size distribution. In this study, we synthesized NMC622 using taylor-couette reactor to understand the function and mechanism of the operation. The effect of operating parameters, i.e. pH, operating rpm, and feed retention time, in the taylor-couette reactor, was investigated thoroughly to evaluate the feasibility to produce NMC622 precursor. Produced precursors are characterized using SEM, XRD, ICP, FIB, PSA. Then, cathode materials are prepared and tested using a galvanostatic intermittent titration method (GITT) to understand the electrochemical properties. This study verified that taylor couette reactor is feasible process to be applied to the commercial NMC622 production.

Li22Si5 alloy powder was synthesized by mechanical alloying and its electrochemical performance was investigated for use in solid-state battery anodes. Two types of anode powder were prepared: 1) Li–Si alloy powder after mechanical alloying with Li-granules and Si-powder, and 2) Li–Si alloy powder from the first process followed by additional ball milling for reduction of particle size. Using these anode materials, all-solid-state lithium batteries were assembled with Li4Ti5O12 (LTO) as cathode and Li2S–P2S5 as electrolyte. Impedance spectra of the two types of cells were measured, and the results showed that the non-ohmic resistance was less in the case of the cell with the secondary ball-milled, fine anode powder. Galvanostatic charge/discharge tests were also performed, and capacity was increased about two times by the additional powder milling process; which is consistent with the impedance results. Thus, the results from the present work indicate that using the secondary milling process to refine the electrode powder is an effective way to increase the kinetics of alloying and de-alloying with improvement in interfacial properties in all-solid-state lithium secondary batteries.

We experimentally clarify the effects of barrier dopings on the polarization induced electric fields and the band structure in InGaN/GaN blue light emitting diodes. Both effects were independently verified by using electric field modulated reflectance and capacitance-voltage measurement. It is shown that the Si barrier doping does reduce the polarization induced electric field in the quantum wells. But the benefit of Si-doping is nullified by modification of the band structure and depletion process. With increased number of doped barriers, smaller number of quantum wells remains in the depletion region at the onset of the diffusion process, which can reduce the effective active volume and enhance the electron overflow.