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This paper reports a two-dimensional modeling to predict the aging effect on the variation of the electrical and thermal behaviors of a lithium-ion battery (LIB) cell under the constant current (CC) charge and discharge cycling over a long time. To account for the aging effects of the LIB cell due to cycling, the key modeling parameters are expressed as a function of cycling number. In order to validate the modeling methodology introduced in this paper, the modeling results towards the changes of the discharge curves and two-dimensional temperature distributions of the aged LIB cell during CC discharge at different C rates are compared with the experimental measurements after every thousand cycles. The electrical and thermal behaviors predicted by the modeling for the aged LIB cell show good agreement with the experimental data.

This paper presents the development of an electrochemical model that can be implemented into automotive battery management systems (BMSs). Compared with empirical models, the electrochemical model features more accurate state estimates over a broader and longer use of the battery. In this work, model implementation schemes are devised to make the electrochemical model uncomplicated enough to be embedded into the BMS. A nonlinear system of partial differential equations in the model is discretized into a linearized system of algebraic equations (AEs). A solver selected to evaluate the resulting system of AEs is modified for its application to the BMS. As the BMS is preoccupied by its existing tasks, the reformulated equations and optimized solver are reorganized such that the limited computational resources of the BMS are appropriately exploited. Consequently, the electrochemical model is implemented into the BMS, predicting battery behaviors in 1 s intervals while occupying a 14 kB RAM.

This paper reports a modeling methodology on the temperature dependence of the discharge behavior of a lithium-ion battery (LIB) in low environmental temperature. The discharge curves from the modeling for the discharge rates ranging from 0.5 C to 5 C under the low environmental temperatures of −20, −10 and 0 °C are compared with the experimental data in order to validate the two-dimensional modeling of the potential and current density distributions on the electrodes of an LIB cell as a function of the discharge time during constant-current discharge. The heat generation rates as a result of electrochemical reactions and ohmic heating are calculated to predict the temperature variations of the LIB as a function of the discharge time. The temperature variations obtained from the modeling agree well with the experimental measurements.

This paper reports on a three-dimensional thermal modeling approach for a lithium-ion battery (LIB). The combined effects of the thermal and electrical contact resistances between the current collecting tab of an LIB cell and the lead wire connecting the cell to an external cycler are considered explicitly in addition to the heat generated as a result of electrochemical reactions and ohmic heating in the electrode region of the battery cell. The effect of electrical contact resistance is taken into account when calculating current collecting tab heating, and the effect of thermal contact resistance is included in the heat flux boundary condition at the contact area between the current collecting tab and the lead wire. The three-dimensional thermal modeling is validated by comparing the modeling results with experimental temperature distributions from IR images during discharge in an LIB cell.

A method for modelling the thermal behaviour of a lithium-ion battery (LIB) during charge is presented. The effect of charge conditions on the thermal behaviour is examined by means of the finite element method. A comparison of the experimental charge curves with the modelling results validates the two-dimensional modelling of the potential and current density distribution on the electrodes of an LIB as a function of charge time during constant-current charge followed by constant-voltage charge. The heat generation rates as a function of the charge time and the position on the electrodes are calculated to predict the temperature distributions of the LIB based on the modelling results for potential and current density distributions. The temperature distributions obtained from the modelling are in good agreement with the experimental measurements.

A local-scale spatially refined multimedia fate model (LSRMFM) was developed to evaluate in detail the multimedia transport of organic compounds at a spatial level. The model was derived using a combination of an advection–dispersion–reaction partial differential equation, a steady-state multimedia fugacity model, and a geographical information system. The model was applied to predicting four major volatile organic compounds that are produced as emissions (benzene, toluene, xylene, and styrene) in an urban and industrial area (the 50 × 50-km area was divided into 0.5 × 0.5-km segments) in Korea. To test the accuracy of the model, the LSRMFM was used to predict the extent of dispersion and the data compared with actual measured concentrations and the results of a generic multimedia fate model (GMFM). The results indicated that the method developed herein is appropriate for predicting long-term multimedia pollution. However, the comparison study also illustrated that the developed model has some limitations (e.g., steady-state assumption) in terms of explaining all the observed concentrations, and additional verification and study (e.g., validation using a large observed data set, integration with a more accurate runoff model) would be desirable. In comparing LSRMFM and GMFM, discrepancies between the LSRMFM and GMFM outputs were found, as the result of geographical effects, even though the environmental parameters were identical. The geographical variation for LSRMFM output indicated the existence of considerable local human and ecological risks, whereas the GMFM output indicated less average risk. These results demonstrate that the model has the potential for improving the management of pollutant levels under these refined spatial conditions.

The development of a mechanistic model for the thermal plant in the district heating system is addressed. Energy balance is composed of the change of enthalpy and the generation of the heat by a fuel combustor, on the basis of several assumptions. Effective thermal capacitance is estimated using the data measured in the heating system of Su-Seo area in Korea, and the validity of the developed model is clearly shown by the comparison of outlet temperatures from the boiler between the model prediction and data measured during the period other than that for the estimation. The model performs satisfactorily, and its usefulness has been illustrated by the application of the model-based controller for the regulation of outlet temperature. The controlled case shows that the temperature is maintained close to the set-point, and the energy saving is expected to be about 10 million USD for a year in the area.

A spatial distribution multimedia fate model is proposed for the rigorous simulation of the environmental multimedia fate of hazardous chemicals emitted from a variety of sources. To solve the relevant equation, we introduce an explicit finite difference method applied to uniform grids. We assessed the numerical properties of the model, including stability and accuracy. A new dimensionless number (multimedia transport number) is proposed for determining the numerical stability of the unsteady-state method. The model was verified by comparison with analytical solutions for the transport of non-conservative substances in two-phase open-channel flow. The spatial resolution of the spatial distribution model was tested via a comparison with a general multimedia fate model in a practical application related to toluene emissions in Seoul, South Korea.

This study describes the full disaggregation process of emission inventory maps in support of environmental modeling studies in a geographical information system. Using a heuristic approach, appropriate algorithms were found to accelerate the computational disaggregation speed. The algorithms were based on scan-conversion algorithms employed in the field of computer graphics. Various algorithms were analyzed in terms of supporting emission inventories with different shapes, such as points, polylines and polygons. The algorithms were implemented by using Visual Basic, thereby enabling the efficiencies of the algorithms to be analyzed and compared with each other. For the disaggregation of polygon types, with the aim of increasing the resolution of an inventory map, we suggest the advanced polygon-disaggregation method with land use data. An air dispersion simulation was performed in order to compare the accuracy of the emission input data generated by existing disaggregation methods and the advanced method proposed in the present study.

Miniaturized systems based on the principles of microfluidics are widely used in various fields, such as biochemical and medical applications. Systematic design processes are demanded for the proper use of these microfluidic devices based on mathematical simulations. In this research, passive mixing, without external forces, was simulated and analyzed with Fluent 6.1. After the simulation process, PDMS-based micro-chips were fabricated for use in experiments. In the experiments, gold nano-particles and CuSO4 solutions were used to visualize their mixing tendencies. Because the gold nano-particles were composed of specific aggregations with metal ions, colorimetric variations could be detected by the naked eye without any optical equipment. The simulation results showed good agreement with the experimental ones. The pressure drop in the micro-mixers was small and, therefore, their structures were deemed to be suitable for integration with lab-on-a-chips or micro-total analysis systems.

Recently, the multi-screening of target materials has been made possible by the development of the surface plasmon resonance (SPR) imaging method. To adapt this method to biochemical analysis, the multi-patterning technology of protein microarrays is required. Among the different methods of fabricating protein microarrays, the microfluidic platform was selected due to its various advantages over other techniques. Microfluidic devices were designed and fabricated with polydimethylsiloxane (PDMS) by the replica molding method. These devices were designed to operate using only capillary force, without the need for additional flow control equipment. With these devices, multiple protein-patterned sensor surfaces were made, to support the two-dimensional detection of various protein-protein interactions with SPR. The fabrication technique of protein microarrays can be applied not only to SPR imaging, but also to other biochemical analyses.

Electrochemistry and nucleation mechanism of induced co-deposition of cobalt, tungsten and phosphorus from a citrate bath was investigated using voltammetry and chronoamperometry techniques. It was found that the induced co-deposition of the species occurred under diffusion control and followed instantaneous nucleation mechanism. Co–W–P coatings were electrodeposited potentiostatically on plain carbon steels from a citrate bath containing CoSO 4 , Na 2 WO 4 and NaH 2 PO 2 . X-ray diffraction studies of the coatings revealed that the as-deposited Co 81 W 10 P 9 coatings had amorphous structure. The formation of some stoichiometric compounds like Co 3 W, Co 2 P and WP 2 , however, was observed upon annealing at 600 °C. The hardness of the Co–W–P coatings increased with annealing temperature which was possibly due to the formation of these inter-elemental compounds. The corrosion resistance of the Co–W–P coatings increased with increase in annealing temperature which might also be due to the formation of the stoichiometric compounds at elevated temperatures. A comparison between coating characteristics of Co–W–P and chromium showed that the Co–W–P coatings exhibited nobler corrosion potential than chromium coatings.

The environmental contamination problems caused by accelerated industrialization are becoming increasingly important issues. It is necessary to estimate the distributions of the contaminants and to recognize the risks to our environment. The behavior of volatile organic compounds (VOC) can be analyzed with the concept of fugacity. However, it is difficult to simulate the fate of heavy metals with this concept, because their vapor pressure is extremely small or unknown. Therefore, the aquivalence (from “equivalent aqueous”) theory, which was derived from the fugacity theory, is utilized to establish a mathematical model and to analyze the fate of heavy metals in an urban multimedia system. The target heavy metal is lead and the target region is around Jungrang stream in Seoul. The multimedia is composed of air, water, sediment, soil and vegetation. To verify the proposed mathematical model, the modeling results were compared with the measurement data obtained from the Korea Testing and Research Institute.

A thermal modeling was performed to study the effect of the electrode configuration on the thermal behavior of a lithium-polymer battery. It was examined the effect of the configuration of the electrodes such as the aspect ratio of the electrodes and the placing of current collecting tabs as well as the discharge rates on the thermal behavior of the battery. The potential and current density distribution on the electrodes of a lithium-polymer battery were predicted as a function of discharge time by using the finite element method. Then, based on the results of the modeling of potential and current density distributions, the temperature distributions of the lithium-polymer battery were calculated. The temperature distributions from the modeling were in good agreement with those from the experimental measurement for the batteries with three different types of electrodes at the discharge rates of 1C, 3C, and 5C.

A three-dimensional modelling approach is used to study the effects of operating and ambient conditions on the thermal behaviour of a NESSCAP 2.7 V/3500 F ultracapacitor cell for a 42-V automotive electrical system. The rate of heat generation of the ultracapacitor during charge and discharge is measured with a calorimeter. The transient temperature distribution of the ultracapacitor during cycling is obtained by using the finite element method with an implicit predictor-multicorrector algorithm. The results show that the temperature of the ultracapacitor cell increases during the first 50 cycles after which it reaches a periodic steady-state value that increases with increasing ambient temperature.

Atomic scale etching (ASE) of poly-Si, which can give etching with atomic scale accuracy, was investigated in inductively coupled Ar and He plasmas. ASE used a cyclic operation of gas adsorption and ion beam irradiation, which is the same concept as atomic layer etching of single crystal substrates. The etch rate gradually increased, reached the saturated region, and then rapidly increased with increasing bias voltage (or ion energy) in both Ar and He plasmas. This saturation region offered a process window for the realization of ASE. At the bias voltage within the process window for ASE, the etch rate was self-limited with respect to the duration of ion beam irradiation for both Ar and He plasmas, confirming that ASE of poly-Si was successfully achieved in both Ar and He plasmas. The range of the process window for ASE using He plasmas was about 10 times wider than that using Ar plasmas. This is because heavier Ar ions impart a greater fraction of ion energy to the surface atoms compared to lighter He ions.

An etching of a SiO2 contact hole with a diameter of 0.19μm and an aspect ratio of 13, using C4F6/Ar/O2/CH2F2 and c-C4F8/Ar/O2/CH2F2 plasmas, was performed for a feasibility test of the use of unsaturated fluorocarbons (UFCs) as an alternative to perfluorocarbon (PFC) gases for a high aspect ratio contact hole etching. The etch profile of the contact hole obtained in the C4F6/Ar/O2/CH2F2 plasma was shown to have 23% lower degree of bowing than that in the c-C4F8/Ar/O2/CH2F2 plasma. The Kelvin and chain contact resistances of the contact holes etched in the C4F6/Ar/O2/CH2F2 plasma were 10-12% higher than those in the c-C4F8/Ar/O2/CH2F2 plasma, but they were within the device spec. The integration of device with 0.1μm design rule using C4F6/Ar/O2/CH2F2 and c-C4F8/Ar/O2/CH2F2 plasmas during the contact hole etching was also conducted, and it was found that etch profiles, metal coverage, and bottom critical dimensions of the contact in the C4F6/Ar/O2/CH2F2 plasma were nearly identical to those in the c-C4F8/Ar/O2/CH2F2 plasma, suggesting that the use of C4F6 gas as an etchant gas for a high aspect ratio contact hole etching can be a good alternative to PFC gases.

Vanadia–titania catalysts prepared by a sol–gel method and by supercritical drying showed a very high activity and thermal stability for gas phase oxidation of 1,2-dichlorobenzene (DCB) in the range of 150–600 °C. The selectivity for carbon oxides was kept over 95% unless the reaction temperature was relatively low ( The surface structure of vanadia played a critical role on the catalytic activity, but the structure of crystalline titania was revealed to have exclusive dependency. For the vanadia–titania catalysts with the inherent characteristics of aerogels such as high specific surface area and chemical homogeneity, little bulk vanadia was observed and catalytic activity was maintained or improved due to the formation of surface mono- and poly-vanadates after repeated reactions.

Interaction of a plasma with a hole on a solid wall bounding that plasma was investigated by measuring the energy and angular distribution of ions extracted through a hole in contact with a high density deuterium plasma. Experiments were conducted by varying the ratio of the hole diameter to the sheath thickness (d/l) and the hole aspect ratio. In contrast to reported studies, holes with diameter larger than as well as smaller than the local sheath thickness were used. At one extreme, when d/l≪1, the plasma was not perturbed by the presence of the hole. The ion energy distribution (IED) had multiple peaks and the ion angular distribution (IAD) was Gaussian, peaking at zero angle with respect to the surface normal. At the other extreme, when d/l≫1, the plasma “leaked” through the hole. The IED had a single peak with a shoulder and the IAD was quite broad extending up to 30° off normal. The IAD was not affected by varying power and pressure suggesting that the plasma leaked completely out of the hole. When d/l≈1, the shape of the IED and IAD was in-between the two extremes mentioned above.

A three-dimensional simulation was performed to predict the flow field and the separation efficiency for particles in a hydrocyclone to be used for the sludge separation in water purifying plants. The Reynolds averaged Navier–Stokes and Reynolds averaged continuity equations employing renormalization group k – e model were solved to calculate the turbulent flow field in a hydrocyclone. The particle trajectories were computed by integrating the force balance equations on particles based on the predicted flow field. The separation efficiency defined as the fraction of particles recovered to underflow was obtained by using the calculated particle trajectories. The separation efficiency of a hydrocyclone for the sludge separation in water purifying plants was measured experimentally as a function of particle size. Simulation results agreed favorably with experimental data.

Using first principles calculations and Monte Carlo simulations, we have examined the validity of the Ising model widely used for the order–disorder phase transition on Si(0 0 1)-2 × 1. Our study suggests that not only dipole–dipole interactions of asymmetric dimers but also subsurface layer strains play an important role in determining the energetics for different surface configurations. Without consideration of the strain effect the Ising model can miscalculate the phase transition significantly. Including the strain effect, a new model Hamiltonian predicts a transition temperature range of 170–200 K, in good agreement with experimental observations (∼200 K). However, the new model still cannot reproduce streak patterns (well above the transition temperature) as seen in low-energy electron diffraction. We discuss a possible reason for the disagreement.

The behavior of chloride ions introduced into concrete from concrete surface by marine environment and by use of marine aggregate was analyzed for a coastal concrete structure. A mathematical model including the diffusion of chloride ion in aqueous phase of pores, the adsorption and desorption of chloride ions to and from the surface of solid phase of concrete, and the chemical reactions of chloride ions with solid phase was presented. Finite element method was employed to carry out numerical analysis. Quantitative analysis was conducted to measure the distribution of the free chloride ion concentration in aqueous phase of concrete with potentiometric titration based on ASTM D 1820. The concentration profiles of chloride ions predicted by the mathematical model agreed favorably with the measured data. The results of this study may be used to predict the onset of reinforcement corrosion and to identify the maximum limit of chloride ions contained in concrete admixtures.

The transport of charged species in collisional currentless plasmas is traditionally thought of as a diffusion-like process. In this paper, it is demonstrated that, in contrast to two-component plasma, containing electrons and positive ions, the transport of additional ions in multispecies plasmas is not governed by diffusion, rather described by nonlinear convection. As a particular example, plasmas with the presence of negative ions have been studied. The velocity of a small perturbation of negative ions was found analytically and validated by numerical simulation. As a result of nonlinear convection, initially smooth ion density profiles break and form strongly inhomogeneous shock-like fronts. These fronts are different from collisionless shocks and shocks in fully ionized plasma. The structure of the fronts has been found analytically and numerically.

Profile evolution simulations during chemical vapor deposition based on a 2D continuum model reveal that the type of surface kinetics plays an important role in determining step coverage of films deposited in high aspect ratio trenches and vias. Linear surface kinetics, resulting from an adsorption rate limited process, is found to cause difficulty in bringing about conformal step coverage in deep narrow trenches without reducing the growth rate considerably. Under such condition, void-free filling cannot be achieved while maintaining a growth rate acceptable to integrated circuit (IC) manufacturing. The numerical study also suggests that the high tendency of the precursor for chemical equilibrium on a surface, resulting in nonlinear kinetics by a surface reaction limited process, is crucial to achieve a uniform step coverage as typically observed in SiO2 deposition from tetraethylorthosilicate (TEOS).

The effect of power modulation oil radical concentration and uniformity in a single-wafer plasma reactor was investigated with a radical transport and reaction model. Plasma etching of silicon using tetrafluoromethane under relatively high pressure (≈l torr) high frequency (13.56 MHz) conditions was taken as an example system. Gas velocity, temperature, and radical concentration profiles were obtained numerically by a finite element method. When compared to a contin uous wave plasma, power modulation can alter the relative concentration of radicals and in turn the each rate and uniformity as well as selectivity and anisotropy Uniformity is improved by power modulation except at high flow rates which, however, result in poor utilization of the feedstock gas.

This paper reports a method of modeling the dependence of the discharge behavior of a lithium-ion battery (LIB) on the environmental temperature. A comparison of the experimental discharge curves for discharge rates ranging from 0.5 to 5 C and environmental temperatures of 15, 25, 35, and 45°C with the modeling results validates the two-dimensional modeling of the potential and current density distributions on the electrodes of an LIB as a function of the discharge time during galvanostatic discharge based on the finite element method. The heat generation rates as a function of the discharge time and the position on the electrodes are calculated to predict the temperature distributions of the LIB based on the modeling results of the potential and current density distributions. The temperature distributions obtained from the modeling are in good agreement with the experimental measurements.

Vanadia–alumina composite aerogels were synthesized by a cogelation method using alcoholic solutions of metal chlorides under acidic conditions. The resulting aerogels exhibited high surface areas and narrow pore size distributions in the mesoporous region. The vanadium oxides existing on the surface of the aerogels predominantly developed into polyvanadates in terms of chemical structure following the introduction of V species up to 40 wt.% with 500 °C calcination. The intensities of the Raman spectra for the polyvanadates increased with vanadia content, while Raman bands shifted towards lower wavenumbers with decreasing vanadia content due to weak V–O bonds. Homogeneity of the surface vanadates on the aerogels was much higher than that on the impregnated materials, as observed in temperature programmed reduction and NH3temperature programmed desorption patterns.

The conditions marking the onset of natural convection due to buoyant forces are investigated in the thermal entrance region of horizontal plane Couette flow. The base temperature profile produced by pure forced convection is approximated as a fourth order polynomial using the integral method. With this approximate base-temperature profile stability criteria are obtained by means of the local stability analysis, its modification, and the natural-amplification analysis. The last one takes into consideration the axial amplification rate of disturbances at the onset of thermal instability. This new concept is tested here for the first time. The consideration of axial amplification of disturbances makes the system more stable. It is shown that the results of the natural-amplification analysis agree well with the existing experimental data.