Young Il Kwon

A study of creep-fatigue life prediction using an artificial neural network

In this study, using AISI 316 stainless steel, creep-fatigue tests were carried out under various test conditions (different total strain ranges and hold times) to verify the applicability of the artificial neural network method to creep-fatigue life prediction. Life prediction was also made by the modified Coffin-Manson method and the modified Ostegren method using 21 data points out of a total 27 experimental data points. The six verification data points were carefully chosen for the purpose of evaluating the predictability of each method. The predicted lives were compared with the experimental results and the following conclusions were obtained within the scope of this study. While the creep-fatigue life prediction by the modified Coffin-Manson method and the modified Ostegren method had average errors of 35.8% and 47.7% respectively, the artificial neural network method had only 15.6%. As a result, the artificial neural network method with the adaptive learning rate was found to be far more accurate and effective than any of the others. The validity of the artificial neural network method for life prediction checked with the six verification data points also proved to be very satisfactory.

Analysis on Convergence in Green Technology Field Using Patent Information

Convergence means that independently existing entities create a new entity with a larger value through chemical bonding. Such convergence requires consilience of knowledge or discipline. Green technology shows a strong nature of convergence, having strong links between technologies rather than being an independent technology. Green technology can help the energy convergence society by producing energy through renewable energy, abandoning the way of growth of inputting large amount of fossil fuel like petroleum and gas, managing energy through a smart grid, storing energy in energy storage facility, and using LED or environment-friendly vehicle. In this study, we will measure the degree of convergence in green technology field to consider which field of technology actually converges in green technology. In the result, it was found that convergence was continuously increasing in green technology field, and the link between solar energy and LED lighting technology was especially strong. This means that convergence is happening between a technology of energy production and a technology that uses energy, and that the society is going forward to energy convergence society through green technology.

Analysis of Research Trends of Organic Solar Cell Using Patent Information

For an efficient solution in the organic solar cell, the requirements may be largely as follows: development of organic semi-conductor material with a low energy band gap, enhancement of efficiency through morphology and surface control and an increase in efficiency utilizing tandem cell and plasmon technology. This study analyzed research trends in these three fields through a network analysis and mapping analysis using thesis information and patent information. It was shown that in case of the enhancement of efficiency through the development of semi-conductor material with an energy band gap on organic solar cell, morphology and surface control, there have been many ongoing studies since 2007. The enhancement technology for efficient utilization of tandem cell and plasmon technology has been frequently studied recently.