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Lithium-ion batteries (LIBs), which store electric energy and can be easy to use when power is needed, are preferred as an energy storage device to expand renewable energy use and improve the efficiency of the power industry. However, when LIBs are charged at a high rate in a low temperature, metallic lithium is deposited on an anode, which could cause safety problems due to internal short circuit. Also, when LIBs are operated at a high temperature, it promotes aging by increasing the SEI and degradation of electrode structure. Thermal management is essential for maintaining the proper temperature of LIBs for energy-storage applications. It is important to develop a thermal modeling methodology to reflect the combined effects the thermal properties of the various components of a battery cell as well as the complex structures of the battery module. In this work, a three-dimensional modeling is carried out to investigate the effects of operating conditions on the thermal behavior of an LIB module. The battery module consisting of 28 prismatic pouch-type LIB cells fabricated by LG Chem. is modeled. The LIB cell has a nominal capacity of 63 Ah and is composed of lithium nickel manganese cobalt oxide (NMC) positive electrodes, graphite negative electrodes, and porous separators impregnated with plasticized electrolyte. In the battery module, 2 cells are connected in parallel, composing a single strand, and then 14 strands are connected in series (2P 14S configuration). The non-uniform distribution of the heat generation rate in an LIB cell within the module is calculated based the modeling results of the potential and current density distributions of the baPttery cell. Thermal modeling of an LIB module is validated by the comparison between the experimental measurements and modeling results.

The lithium-ion battery (LIB) is the primary choice for many applications such as mobile electronics, electric vehicles, and stationary energy storage solutions due to its high energy density, high voltage and low self-discharge rate. The service life of LIB for such applications is generally limited by aging, although it depends strongly on the usage conditions. The aging of LIB manifests itself in the variation of electrical and thermal behaviors such as capacity fade, cell voltage drop under load, and peak temperature rise during cycling. It is of intense interest to predict accurately the cycle life of the commercial LIB by including the effect of aging. In this work, a modeling is performed to predict the cycle life of an LIB cell during cycling over a long time. This work adopts a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. By not computing the potential distribution of electrolyte phase and the transport phenomena of ionic species, the modeling method in this work cuts down considerable computation time in comparison with rigorous electrochemical models. The validation of the modeling approach is provided through the comparison of the modeling results with the experimental measurement data.

The lithium-ion battery (LIB) is a preferred power source for battery electric vehicles (BEVs),because LIBs have higher energy density, longer life and higher power density than most other practical batteries. Although there is still a plenty of room to be improved for the cost, life, and safety of the LIB in BEV applications,another important issue to be overcome for the BEV battery is searching for an appropriate fast charge protocol to enable a rapid growth of BEV market. A short charge time, however, results in a rapid temperature rise of an LIB cell during charge. Therefore, it is essential to find an optimized fast charge protocol that can keep the peak temperature of LIB cell below the maximum allowable limit recommended by the LIB manufacturer. In this work, the effect of fast charge protocol on the temperature rise of an LIB cell during charge is analyzed based on the two-dimensional thermal modeling of the LIB cell under various fast charge protocols. The thermal modeling during fast charge is validated by the comparison of the modelling results with the experimental measurements using IR thermal images and thermocouples. The fast charge protocols are evaluated based on the peak temperatures of the LIB cell after charge.

In this paper, we report a modeling methodology on the transient behaviors of a lithium-ion battery (LIB) during dynamic cycling. To account for the short time effects of current pulses and rest periods, the nonfaradaic component of the current density transferred through the separator between the positive and negative electrodes is included based on the lumped double-layer capacitance. Two-dimensional modeling is performed to predict the transient behaviors of an LIB cell during dynamic cycling. To validate the modeling approach presented in this work, modeling results for the variations in cell voltage and two-dimensional temperature distribution of the LIB cell as a function of time are compared with the experimental data for constant-current discharge and charge cycles and the Heavy Duty Urban Dynamometer Driving Schedule cycles. The transient behaviors obtained from the modeling agree well with the experimental measurements.

Ultracapacitors (UCs), known by different names such as supercapacitors, electrochemical double-layer capacitors, double-layer capacitors or electrochemical capacitors, have the potential to meet the high pulse power capability of the energy-storage systems for automotive applications. The primary advantages of UCs are higher power density and longer shelf and cycle life as compared to those of batteries. In the high pulse power operations for automotive applications, a large amount of heat is produced inside a UC cell. Because the lifetime and performance of a UC depend strongly on temperature, it is important to predict accurately the thermal behaviors of a UC for the efficient and reliable systems integration from an application perspective. In this work, a three-dimensional thermal model is presented to predict the thermal behaviors of the UC. Both of the irreversible and reversible heat generations inside the UC cell are considered. The effective density and specific heat capacity of the various compartments of the cell are estimated based on the mass fractions of the components of each cell compartment. The effective thermal conductivities of the various compartments of the cell are estimated based on the equivalent networks of parallel and series thermal resistances of the cell components. The validation of the three-dimensional thermal model is provided through the comparison of the modeling results with the experimental IR image at various charge/discharge currents.

An absorbent glass mat (AGM) lead-acid battery is a type of valve-regulated lead-acid (VRLA) battery. An AGM lead-acid battery differs from a flooded lead-acid battery in that the sulfuric acid is absorbed in a very fine fiberglass mat, making the battery spill-proof. The leading advantages of AGM type are a higher specific power, lower internal resistance, five times faster charge speed than the flooded version, and the ability to deep cycle. AGM lead-acid batteries are found in high-end vehicles equipped with more electronic devices and making inroads into the start-stop function of cars. A validated mathematical model for the accurate prediction of the charge and discharge behaviors of an AGM lead-acid battery in real-world driving conditions is necessary to ensure that the battery can provide enough power for the rising number of electrical components. In this work, a method of modeling the charge and discharge behaviors of an AGM lead-acid battery under various operating conditions is presented. This work adopts a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. By not computing the potential distribution of electrolyte phase and the transport phenomena of ionic species, the modeling method in this work cuts down considerable computation time in comparison with rigorous electrochemical models. The model is validated by comparing the modeling results with the experimental measurements.

The lithium-ion battery (LIB) is the primary choice for many applications such as mobile electronics, electric vehicles, and stationary energy storage solutions due to its high energy density, high voltage and low self-discharge rate. Reported safety incidents related to LIBs have resulted in an increased attention toward the safety issue of the LIB. In the operation of LIBs, there are many sorts of field failures including overheat, overcharge, and short circuit. External short circuit (ESC) is a severe fault which causes the large current flow and high temperature rise in an LIB immediately. Modeling to predict the maximum current flow and temperature rise of an LIB under ESC fault is essential to design an effective fault detection and diagnosis system for the safety management of LIB. In this work, a modeling is performed to predict the electrical and thermal behaviors of an LIB cell under ESC conditions. The validation of the modeling approach is provided through the comparison of the modeling results for a 75Ah LIB cell from KOKAM with the experimental measurement data obtained from the ESC tests. The ESC tests were carried out using the external resistances of 0, 2, and 5 mΩ. Model predictions reasonably reproduce the experimental data.

The zinc/bromine (Zn/Br2) flow battery is an attractive rechargeable system for energy storage because of its inherent chemical simplicity, high degree of electrochemical reversibility at the electrodes, good energy density, and abundant low-cost materials. Because the performance of a Zn/Br2 flow battery depends strongly on the operating temperature, it is important to develop a mathematical model to predict the performance of the battery as a function of the operating temperature in order to estimate such quantities as current efficiency and conversion per pass. This information can be used to design both of bench and production scale cells and to select the operating conditions for optimum performance. In this work, a method of modeling the dependence of the charge and discharge curves of a Zn/Br2 flow battery on its operating temperature is presented. This work adopts a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. To accommodate the temperature dependence, the key modeling parameters are expressed as the functions of temperature based on the well-known principles of the Arrhenius equation of chemical kinetics and the Nernst equation of electrochemical thermodynamics. The model is validated by comparing the modeling results with the experimental measurements.

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.

For the optimal design of the vehicle electric system, it is important to have a reliable modeling tool to predict the dynamic behavior of the automotive battery. In this work, a one-dimensional modeling was carried-out to predict the dynamic behaviors of a 12-V automotive lead-acid battery. The model accounted for electrochemical kinetics and ionic mass transfer in a battery cell. In order to validate the modeling, modeling results were compared with the experiment data of the dynamic behaviors of the lead-acid batteries of two different capacities that were mounted on the automobiles manufactured by Hyundai Motor Company. The discharge behaviors were measured with various discharge rates of C/3, C/5, C/10, C/20 and combination. And dynamic behaviors of charge and discharge were measured. The voltage curves from the experiment and simulation were in good agreement. Based on the modeling, the distributions of the electrical potentials of the solid and solution phases, and the current density within the electrodes could be predicted as a function of charge and discharge time.

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 district heating system produces thermal energy and supplies it to a large region. District heating systems can provide higher efficiencies and better pollution control than localized boilers. The heat generated by a district heating system is distributed to the customer via a network of insulated pipes. For the optimal operation of a district heating system, it is important to predict the distributions of pressure, flow rate and temperature of heating fluid within the network of pipes at various operating conditions. In this work, a mathematical modeling was performed to predict the dynamic hydraulic-thermal behaviors of heating fluid in the network of pipes for a district heating system. The mathematical model accounts for the conservations of mass, momentum and energy. In order to verify the validity of modeling, the modeling results were compared with the monitoring data of Gang-nam Branch of District Heating.

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.

The lithium ion diffusion coefficients of bare, carbon-coated and Cr-doped were obtained by fitting the discharge curves of each half cell with Li metal anode. Diffusion losses at discharge curves were acquired with experiment data and fitted to equations. Theoretically fitted equations showed good agreement with experimental results. Moreover, theoretical equations are able to predict lithium diffusion coefficient and discharge curves at various discharge rates. The obtained diffusion coefficients were similar to the true diffusion coefficient of phase transformation electrodes. Lithium ion diffusion is one of main factors that determine voltage drop in a half cell with cathode and Li metal anode. The high diffusion coefficient of carbon-coated and Cr-doped resulted in better performance at the discharge process. The performance at high discharge rate was improved much as diffusion coefficient increased.

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.

The battery is the primary reason that hampers a mass adoption of electric vehicles (EVs). Although lithium ion battery (LIB) is a preferred power source for EV, there is still a plenty of room to be improved for the cost, life and safety of the LIB in EV applications. Another important issue to be overcome for the EV battery is searching for an appropriate fast charge protocol to alleviate “range anxiety” for the driver of passenger EV and thus to enable a rapid growth of EV market. A short charge time is, however, reported to be achieved always at the expense of cycle life regardless of the charge techniques. It is, therefore, essential to find an optimized fast charge protocol that can balance fast charge and healthy cycling for the LIBs. In this work, the thermal behaviors of LIB cell under various fast charge protocols are analyzed based on the two-dimensional modeling of the nonuniform temperature distribution in LIB cell during fast charge. The thermal modeling during fast charge is validated by the comparison of the modelling results with the experimental measurements using IR thermal images and thermocouples. The fast charge protocols are evaluated based on the peak temperature of LIB cell and the thermal imbalance within LIB cell during fast charge. The maximum, average, and minimum temperatures obtained from the experimental measurements are compared with those predicted by the model in Fig. 1. The maximum, average, and minimum temperatures obtained from the experiment and modelling are in good agreement with each other at charge rate of 5C during CC-CV charging. Fig. 2 shows the temperature distributions based on the experimental IR image and the modeling for a 14.6 Ah LIB at an environmental temperature of 25℃ at charge time of 180, 480, 1140 s during CC-CV charging with CC charge at 5C. The overall temperature distributions obtained from the experiment agree well with those from the modeling in Fig. 2. Figure 1

The lithium-ion battery (LIB) is the primary choice for electric vehicle (EV) applications due to its high energy density, high voltage and low self-discharge rate. The service life of LIB for EV applications is generally limited by aging and the aging of LIB depends strongly on the thermal history during usage. In order to secure the resilience of LIB for the EV applications, it is essential to develop a modelling tool that has a capability to account for the relationship between the aging and thermal history of LIB to design an optimal battery management system. In this work, a modeling is performed to predict the effect of aging on the performance decay an LIB as well as variation of thermal behaviours during cycling for a long time. The validation of the modeling approach is provided through the comparison of the modeling results for a 14.6Ah LIB cell from LG Chem. with the experimental measurement data obtained from the cycling tests. The cycling tests were performed under the protocol of the constant-current charge and the constant-current discharge. In Fig. 1, the discharge capacities measured at every thousand cycles for discharge rates of 1C, 3C, and 5C were compared with those calculated from the modeling. The modeling results and the experimental data on the capacity fade of the aged LIB cell are in good agreement in Fig. 1. Fig. 2 shows the temperature distributions from the experimental IR image and the modeling for the LIB at an environmental temperature of 25 ˚C at times of 240, 480, and 636 s during the CC discharge with a rate of 5C after 1000 cycles. Model predictions reasonably reproduce the experimental data. Figure 1

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.

CoWP films were electrochemically deposited on copper-coated silicon wafers from citrate electrolytes containing cobalt sulphate, sodium tungstate and sodium hypophosphite under various deposition conditions and characterisations of the films were carried out using various instrumental techniques. Composition analyses using XPS showed that the surfaces of the films contained large amounts of oxides and hydroxide of tungsten and cobalt, respectively. An AES depth-profile, however, revealed that the bulk of the films predominantly consisted of cobalt, tungsten and phosphorus. Microstructural analyses using XRD showed that, depending on the composition and/or deposition conditions, CoWP films could be amorphous, polycrystalline and crystalline with a strong preferred orientation. Amorphous films were obtained when deposited at higher applied potential and current density or the films contained high amount of phosphorus and/or tungsten, while films deposited by very low applied potential and current density were crystalline with a preferred orientation of [0 0 2] of hexagonal cobalt. SEM images showed that the films deposited from neutral or acidic baths at room temperature had typical spherical nodular structures, while the films deposited from basic solution or at elevated temperature had needle-like crystallites. The crystalline films were much rougher than the amorphous films.

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.

CoWP films were electrodeposited on copper-coated silicon wafers from citrate electrolyte containing cobalt sulphate, sodium tungstate and sodium hypophosphite at room temperature potentiostatically. The effects of electrolyte concentration on thickness, composition and microstructure of the films were studied. It was observed that the deposition current density and thickness increased with increasing cobalt and hypophosphite ion concentrations, whereas an increase in tungstate ion concentration resulted in a decrease in current density and thickness. Films with larger variations of cobalt (from 64 to 83 at.%), tungsten (from 0.5 to 24 at.%) and phosphorus (from 6 to 21 at.%) were electrodeposited by controlling the concentrations of the electrolytes. X-ray diffraction studies suggested that films containing ∼20 at.% phosphorus were amorphous while films with lower phosphorus content were crystalline. SEM and AFM examinations showed that the size of crystallites and surface roughness were mainly dependent on the amount of phosphorus present in the films.

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.

The potential and current density distribution on the electrodes of a lithium-polymer battery were studied by using the finite element method. The effect of the configuration of the electrodes such as the aspect ratio of the electrodes and the size and placing of current collecting tabs as well as the discharge rates on the battery performance was examined to enhance the uniformity of the utilization of the active material of electrodes. The results showed that the aspect ratio of the electrodes and the size and placing of current collecting tabs have a significant effect on the potential and current density distribution on the electrodes to influence the distribution of the depth of discharge on the electrodes, thus affecting the uniform utilization of the active material of electrodes.

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.

An Al dual damascene process for the metallization of sub-100 nm dynamic random access memory devices was performed, and the effects of wafer cleaning method on the damascene structures and their electrical properties were investigated. Interconnect structures obtained with the Al dual damascene process using the conventional NH4OH-based wet cleaning (Type I) and the wet cleaning followed by CF4/Ar-plasma dry cleaning (Type II) showed that the metal lines having the aspect ratio of 3 were patterned without gap-filling of inter metal dielectrics. All the sheet resistances of metal lines using the two different wafer cleaning methods during the Al dual damascene process were within specification. The via resistance distributions, however, depended on the cleaning method, and it was found that the cleaning Type II produced a 100% yield and very narrow distribution of the contact resistances of the 0.24 μm-diameter via due to the efficient removal of stable AlxOy species for cleaning Type II.

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.