Electrochemical characteristics of LiNi0.9Co0.1O2 synthesized at 800 °C from the different combinations of carbonates and oxides

Cathode active materials with a composition of LiNi_0.9Co_0.1O₂ were synthesized by a solid-state reaction method at 800 °C using Li₂CO₃, NiO or NiCO₃, and CoCO₃ or Co₃O₄ as the sources of Li, Ni, and Co, respectively. The electrochemical properties of the synthesized samples were then investigated. The structure of the synthesized LiNi_0.9Co_0.1O₂ was analyzed, and the microstructures of the samples were observed. The curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂ for the first charge–discharge and the intercalated and deintercalated Li quantity Δx were studied. The LiNi_0.9Co_0.1O₂ sample synthesized from Li₂CO₃, NiCO₃, and Co₃O₄ had the largest first discharge capacity (152 mAh/g), with a discharge capacity deterioration rate of 1.4 mAh/g/cycle.     

Electrochemical performance of cobalt-substituted lithium nickel oxides synthesized from lithium and nickel carbonates and cobalt oxide

LiNi_1?yCo_yO₂ (y=0.1, 0.3 and 0.5) cathode materials were synthesized by a solid-state reaction method at different temperatures using Li₂CO₃ as a Li source, NiCO₃ as a Ni source, and Co₃O₄ as a Co source. The electrochemical properties of the synthesized samples were then investigated. Structures of the synthesized LiNi_1?yCo_yO₂ (y=0.1, 0.3 and 0.5) samples were analyzed, and microstructures of the samples were observed. Voltage vs. x in Li_xNi_1?yCo_yO₂ curves for the first and second charge–discharge cycles and intercalated and deintercalated Li quantity Δx were studied. LiNi_0.9Co_0.1O₂ synthesized at 800 °C had the largest first discharge capacity (152 mAh/g) and quite good cycling performance, with a discharge capacity of 146 mAh/g at n=5. It had a discharge capacity fading rate of 1.4 mAh/g/cycle.     

Global scheduling with code-motions for high-level synthesisapplications

In this paper, we present a global scheduling technique for synthesis applications. The algorithm accepts a specification containing conditional branches and while-loop constructs and schedules it for a given set of resources. The algorithm performs several types of code motions across different basic blocks and trades off cost with performance. Several real-life examples taken from Numerical Recipes in C are used to demonstrate the efficacy of the approach. The results indicate that code-motions are very important for achieving significant speed-ups for synthesis applications     

A high-speed, high-sensitivity silicon lateral trench photodetector

We report a novel silicon lateral trench photodetector that decouples the carrier transit distance from the light absorption depth, enabling both high speed and high responsivity. The photodetector, fabricated with fully VLSI compatible processes, exhibits a 6-dB bandwidth of 1.5 GHz at 3.0 V and an external quantum efficiency of 68% at 845 nm wavelength. A photoreceiver with a wire-bonded lateral trench detector and a BiCMOS transimpedance amplifier demonstrates excellent operation at 2.5 Gb/s data rate and 845 nm wavelength with only a 3.3 V bias     

The Sources and Directions of Technological Capability Accumulation in Korean Semiconductor Industry

In this paper we analyze the technological accumulation processes in the Korean semiconductor industry from the institutional approach. Institutional approach, which is closely connected with Neo-Schumpeterian tradition, has emerged as an alternative theoretical framework to neoclassical approach to understand the process of producing technological knowledge. Traditional wisdom of neoclassical approach revealed the limitation to explain the complex nature of knowledge creation and diffusion. US patent data are analyzed in terms of the increasing trend of numbers and its content to measure the rate and direction of technological capability accumulation. This analysis shows that semiconductor technologies are one of the fastest growing fields among Korean technological activities. Moreover, the analysis of patent content suggests that fabrication technologies are the most important area within the technological development of semiconductors, whilst circuit design and testing technologies are beginning to increase in significance. In addition, it is examined how private sectors and public institutions have contributed to generate technological capabilities, and the relationship between them has been changed during the development processes. It is found that Korean firms enhanced their technological capabilities from the learning and assimilation of imported technology to enhanced in-house R&D capabilities in the later stage. The support of public institution and government policy also played significant role to this successful transformation in conjunction with the vigorous R&D investment of public sector.     

Novel zero-voltage-transition current-fed full-bridge PWM converterfor single-stage power factor correction

A novel zero-voltage-transition (ZVT) current-fed full-bridge pulsewidth modulation (PWM) power converter for single-stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter. A simple auxiliary circuit which includes only one active switch provides a zero-voltage-switching (ZVS) condition to all semiconductor devices (two active switches are required for the previous ZVT converter). This leads to reduced cost and a simplified control circuit compared to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed power converter are presented and verified by the experimental results from a 1.5 kW 100 kHz laboratory prototype     

Modeling and analysis of static and dynamic characteristics forbuck-type three-phase PWM rectifier by circuit DQ transformation

The static and dynamic characteristics of buck-type three-phase pulse width modulation (PWM) rectifier are fully analyzed based on the DC and AC circuit models developed by the circuit DQ transformation. Various static power converter characteristics such as gain, real and reactive power, power factor and unity power factor conditions are completely analyzed. Transition characteristics are also analyzed by both exact small-signal models with full set of equations and simplified output models in explicit form. The usefulness of the models is verified through computer simulations and experiments with good agreement shown     

Measuring Economic Externalities of IT and R&D

We measure and compare externalities of IT and R&D capital stocks in different Korean industry sectors using inter‐industry input‐output tables of 1985, 1990, 1995 and 2000. We also compute the multiplier effects that relate to the directions of future economic effects. The key findings are as follows. First, we observed continuous capital deepening in all nine industries over the period of 1985 to 2000. Second, the backward multipliers of IT capital were the highest in the manufacturing industry. As for inter‐industry externalities, the indirect backward multipliers, which exclude intra‐industry backward multiplier effects within the industry, were also the highest in the manufacturing industry. Third, the forward multiplier effects of IT capital stock were the most substantial in the construction industry during the 1980s and in the manufacturing industry thereafter. Finally, using the transition multiplier matrix reflecting the backward effects of the two capitals in the past, the economic backward effects, especially the external economic effects, are predicted to increase through 2010 among all industries. The above findings suggest that, in order to maximize the forward and backward effects of the ever‐increasing IT capital, we need to formulate an industry policy reducing the cost of capital accumulation in the manufacturing industry through improvement in productivity of the IT industry.     

Optimal and heuristic algorithms for solving the binding problem

In this paper we present an optimal and a heuristic approach to solve the binding problem which occurs in high-level synthesis of digital systems. The optimal approach is based on an integer linear programming formulation. Given that such an approach is not practical for large problems, we then derive a heuristic from the ILP formulation which produces very good solutions in order of seconds. The heuristic is based on a network flow model and also considers floorplanning during the design process to minimize the interconnection area     

TiO2 hollow spheres as effective additives in oligomer electrolytes for dye-sensitized solar cells

TiO₂ hollow spheres are employed as an additive of oligomer electrolytes for dye-sensitized solar cells (DSSCs). The measurement of steady-state currents confirms that introducing TiO₂ hollow spheres can facilitate ionic diffusion in oligomer electrolytes. Even compared with conventional nanoparticle additives, the hollow spheres are more favorable to increase the diffusion coefficients of I^? and I₃^? in oligomer electrolytes. Furthermore, the hollow structure with a submicron size is effective to scatter incident light and thereby enhance the light-harvesting efficiency of DSSCs. The energy-conversion efficiency of the DSSCs with TiO₂ hollow sphere additives significantly improves up to 7.22% due to the facilitated ionic diffusion and the enhanced light-harvesting efficiency.