Tae-U Yu

Structuring of conductive silver line by electrohydrodynamic jet printing and its electrical characterization

A set of silver lines with a few hundred nanometers in thickness and with a few hundred micrometers in width were obtained using the electrohydrodynamic jet printing. The lines exhibited about three times higher resistivity (4.8 μΩcm) than that of bulk silver after thermal sintering process. The characteristic impedance of the silver line was about 18 Ω while the value calculated was 20 Ω. This paper demonstrated the possibility of using electrohydrodynamic jet printing of silver nanoparticles to obtain conductive line onto circuit boards.

Effect of swirling flow by normal injection of secondary air on the gas residence time and mixing characteristics in a lab-scale cold model combustor

The present study investigates gas residence time and mixing characteristics for various swirl numbers generated by injection of secondary air into a lab-scale cylindrical combustor. Fine dust particles and butane gas were injected into the test chamber to study the gas residence time and mixing characteristics, respectively. The mixing characteristics were evaluated by standard deviation value of trace gas concentration at different measurement points. The measurement points were located 25 mm above the secondary air injection position. The trace gas concentration was detected by a gas analyzer. The gas residence time was estimated by measuring the temporal pressure difference across a filter media where the particles were captured. The swirl number of 20 for secondary air injection angle of 5° gave the best condition: long gas residence time and good mixing performance. Numerical calculations were also carried out to study the physical meanings of the experimental results, which showed good agreement with numerical results.

Design of electrohydrodynamic lens for stabilizing of eletrohydrodynamic jet printing

The generation of micro patterns from conductive material suspensions is gaining significant interests for its usages in the fabrication of flexible display elements and flexible printed circuit boards. In this paper, we presented the results of line patterns of silver nanoparticles obtained by using various types of focusing lenses for electrohydrodynamic jet printing. The pattern widths were measured as 80~100 μm when the electrohydrodynamic lens having a cone-type inner hole and a cone-type outer wall was used. Electric field strengths were calculated by a commercial solver packages for the four types of electrohydrodynamic lenses. A lens having a cone-type inner hole and a cone-type outer wall of thinner thickness was found to be the best design.

Combustion characteristics of simulated gas fuel in a 30 kg/h scale pyrolysis-melting incinerator.

Combustion characteristics of gas fuel in a pyrolysis-melting incinerator having a 30 kg/h capacity were investigated. Pyrolyzed gas from waste was simulated by propane that was injected in the combustion chamber, and burnt through multi-staged combustion by distributing the combustion air to primary, secondary, and tertiary air nozzles. Temperatures and the concentrations of gas components in the combustion chamber were measured. Combustion performance was evaluated with respect to the temperature distribution and combustion gas concentrations of O2, CO and NOx. Using secondary air and/or tertiary air, the combustion performance was improved, and, in particular, NOx concentration decreased significantly following the tertiary air injection.

Effect of Swirling Flow by Normal Injection of Secondary Air on the Gas Residence Time and Mixing Characteristics in a Combustor

We investigated gas residence time and mixing characteristics due to various swirl numbers generated by normal injection of secondary air to a lab-scale cylinderical combustor. The residence time was estimated by measuring the temporal pressure difference which was caused by deposition of test particles on a filter media after the injection by a syringe. The mixing characteristics were evaluated by standard deviation value of test gas concentration at different measuring points. The test gas concentration was detected by a gas analyzer. The swirl number of for

Study of the pyrolysis of biomass using thermo-gravimetric analysis (TGA) and concentration measurements of the evolved species

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