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Your search keyword '"Hwang, J. S."' showing total 19 results
Start Over Author "Hwang, J. S." Publication Type Conference Materials
19 results on '"Hwang, J. S."'

16. Digital Phased Array Ultrasonic Inspection system with dynamic focusing.

Author

Hwang, J. S., Shin, H. J., Song, S. J., and Song, T. K.

Subjects
PHASE transitions, IMAGE quality in diagnostic ultrasonic imaging
Abstract

Enhancement of the ultrasonic flaw detection and characterization is expected through the development of a high performance PAULI (Phased Array Ultrasonic Inspection) system which can provide high resolution two-dimensional (sector scan: S-scan) images. The high-resolution S-scan image renders inspection results more readable compared to the conventional A-scan and B-scan results. Therefore, it can improve inspection efficiency and reliability. In this study, the ultrasonic imaging technologies developed in medical applications were adapted to develop a digital PAULI system for nondestructive testing. To provide real-time S-scan images, the PAULI system uses 64 independent transceiver channels controlled by proper delay laws for steering and focusing the ultrasound beams along each scan lines. The PAULI system employs a novel dynamic receive focusing technique in order to optimize the lateral resolution by focusing the ultrasound wave at all imaging points. The dynamic receive focusing is achieved in real-time by digital signal processing methods. The feasibility of PAULI system is demonstrated for the NDE of steel structures. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

18. Dielectrophoretically Formed Single Wall Carbon Nanotube Network on Polyether Sulfone.

Author

Kim, T. G., Hwang, J. S., Kang, J., Kim, S., Roth, S., Dettlaff-Weglikowska, U., and Hwang, S. W.

Subjects
SINGLE walled carbon nanotubes, ELECTROPHORESIS, POLYETHERS, SULFONES, MICROFABRICATION, SCANNING electron microscopy, DENSITY, ELECTRIC conductivity
Abstract

AC dielectrophoresis (DEP) is a useful method to fabricate single wall carbon nanotube (SWCNT) network structures on various kinds of substrates. We report on the fabrication of SWCNT networks with varying densities, on transparent and flexible polyether sulfone (PES) substrates by using DEP. From the scanning electron microscope observations and current-voltage measurements of the fabricated SWCNT network, we obtain the contour map of the density and conductance as functions of Vp-p and f. Our results show that the maximum density does not necessarily imply the maximum conductance. We find that there exists an optimum density for the maximum conductance. [ABSTRACT FROM AUTHOR]

Published
2011
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