Improving the efficiency of a dye-sensitized solar cell with a reflex condenser system.

Dye-sensitized solar cells (DSSCs) are inexpensive to manufacture and easy to process in comparison with silicone solar cells, but they are difficult to commercialize due to their low efficiency. Accordingly, the aim of this study was to improve the efficiency of a DSSC via an aluminum film reflective plate, reusing discarded light after it was absorbed. We found that the factor having the most dominant influence on DSSC efficiency was the amount of radiation reacting with the dye. For a reflective plate with [symbol: see text] = 30° and h = 15 mm, DSSC efficiency was increased about three times.

Improving the efficiency of a dye-sensitized solar cell with a reflex condenser system.

Dye-sensitized solar cells (DSSCs) are inexpensive to manufacture and easy to process in comparison with silicone solar cells, but they are difficult to commercialize due to their low efficiency. Accordingly, the aim of this study was to improve the efficiency of a DSSC via an aluminum film reflective plate, reusing discarded light after it was absorbed. We found that the factor having the most dominant influence on DSSC efficiency was the amount of radiation reacting with the dye. For a reflective plate with θ = 30° and h = 15 mm, DSSC efficiency was increased about three times.

The characteristics of machined surface controlled by multi tip arrayed tool and high speed spindle.

In this study, we propose one of the ultra-precision machining methods that can be adapted brittle material as well as soft material by using multi arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because particles of grinding tools are irregular size and material can be fragile. Therefore we were able to design tool paths and machine controlled pattern on surface by multi arrayed diamond tips which has uniform size made in MEMS fabrication and high speed spindle of which maximum speed is about 300,000 rpm. We defined several parameters that can have effect on machining surface. Those are multi array of diamond tips (n * n), speed of the air spindle, and feeding rate. Surface roughness and surface texture can be controlled by those parameters for micro machining.

The characteristics of variable speed inchworm stage using lever mechanism by different materials.

Currently, piezoelectric actuators which have attractive features such as high output force, high positioning resolution, high stiffness and quick response have been used in many ultra precision stages. But their positioning ranges are very small. This very limited displacement severely restricts the actuator's immediate implementation for long-range positioning. This paper shows a variable speed inchworm type stage with hinge structures as lever mechanism for nanometer resolution with large dynamic range and studies on characteristics of it. The inchworm stage has hinge structure levers which can shift their pivot position. And it can amplify/reduce output displacement using mechanical advantage with a lever. Especially we suggest guide-line of design according this work that was performed using different materials of stages (Aluminium and Stainless Steel). As the results of simulations, the larger lever ratio is, the smaller stiffness of lever portion is. As the results of experiments, when we input voltage into the inchworm stage, output displacement of each lever is different according to material. Hysteresis of stage could also present that grow according as lever rate rises and stiffness of material. In the case of feeding speed, Aluminium with less hardness showed excellent responsiveness, hence excellent feed performance results.

Surface patterning for brittle amorphous material using nanoindenter-based mechanochemical nanofabrication.

This paper demonstrates a micro/nanoscale surface patterning technology for brittle material using mechanical and chemical processes. Fused silica was scratched with a Berkovich tip under various normal loads from several mN to several tens of mN with various tip rotations. The scratched substrate was then chemically etched in hydrofluoric solution to evaluate the chemical properties of the different deformed layers produced under various mechanical scratching conditions. Our results showed that either protruding or depressed patterns could be generated on the scratched surface after chemical etching by controlling the tip rotation, the normal load and the etching condition. In addition, the mask effect of amorphous material after mechanical scratching was controlled by conventional mechanical machining conditions such as contact area, chip formation, plastic flow and material removal.