Hanyang University · 工学
Professor Kyung-Young Jhang's research lab specializes in ultrasonic nondestructive evaluation and characterization of materials, with a strong focus on nonlinear ultrasonics for assessing material degradation and microstructural changes. The lab investigates the application of advanced ultrasonic techniques—such as bispectral analysis, laser-ultrasonics, and surface wave measurements—to evaluate plastic deformation, porosity, grain structure, and aging effects in metals, including steels, additively manufactured components, and reactor materials. Their work bridges fundamental ultrasonic physics with practical industrial applications, particularly in nuclear energy, semiconductors, and advanced manufacturing.
Figures are computed from collected data and may differ slightly.
Nonlinear ultrasonics is suggested as a new approach for the effective evaluation of material degradation. As its quantification, the parameter beta is introduced on the basis of nonlinear elasticity, and a new method to measure the parameter beta using bispectral analysis is proposed. Then, the correlation between beta and material degradation is investigated. From the results for several mild steel (SS41, SS45) specimens that were degraded by stretching and cyclic loads, it was confirmed that
Metal additive manufacturing (AM) is an innovative manufacturing technology that uses a high-power laser for the layer-by-layer production of metal components. Despite many achievements in the field of AM, few studies have focused on the nondestructive characterization of microstructures, such as grain size and porosity. In this study, various microstructures of additively manufactured metal components were characterized non-destructively using linear/nonlinear ultrasonic techniques. The contrib
The ultrasonic nonlinear parameter is measured from the amplitudes of the harmonic frequency components generated during the propagation of ultrasonic waves in a material. There are two definitions for this parameter: absolute and relative. The absolute parameter is defined by the displacement amplitude; however, it is difficult to measure because of the very small displacement amplitude of the harmonic components. Conversely, the relative parameter is defined by the amplitude of the detected si
In the semiconductor industry, with increasing requirements for high performance, high capacity, high reliability, and compact components, the crack has been one of the most critical issues in accordance with the growing requirement of the wafer-thinning in recent years. Previous researchers presented the crack detection on the silicon wafers with the air-coupled ultrasonic method successfully. However, the high impedance mismatching will be the problem in the industrial field. In this paper, in
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