8. Design, analysis, and experimental validation of a stepped plate parametric array loudspeaker 

Woongji Kim, Beomseok Oh, Chayeong Kim, and Wonkyu Moon*
Journal of the Acoustical Society of America 158, 2561-2576, 2025 [IF: 2.3, JCR: 42.7% in Acoustics]
(doi: 10.1121/10.0039368) 

7. Bidirectional Asymmetric Frequency Conversion in Nonlinear Phononic Crystals 

Yeongtae Jang†, Beomseok Oh†, Eunho Kim* and Junsuk Rho*
Physical Review Letters  135, 036603, 2025 [IF: 9.0, JCR: 7.5% in Physics, Multidisciplinary]
(doi: 10.1103/3n97-7kmd) 

High notes from one side, deep tones from the other
In this study, we demonstrate bidirectionally asymmetric frequency conversion in the gradient phononic crystals. By harnessing the interplay of intrinsic local resonance coupling, spatial asymmetry, and nonlinearity, we realize both frequency up- and down-conversion within the same local-resonance branch.

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6. An accurate measurement of parametric array using a spurious sound filter topologically equivalent to a half-wavelength resonator

Woongji Kim†, Beomseok Oh†, Junsuk Rho* and Wonkyu Moon*
Applied Acoustics  240, 110910, 2025 [IF: 3.6, JCR: 15.9% in Acoustics]
(doi: 10.1016/j.apacoust.2025.110910)
Related data file available at [zenodo.15055891]

New type of acoustic filter using high-Q resonance for PA sound measurement
Parametric arrays (PAs) exploit the nonlinear interaction of ultrasonic waves to produce highly directional audio beams. However, practical measurement and evaluation of PAs remain technically challenging due to the inherent presence of spurious sound signals. In this work, we develop a resonator-based acoustic filter that effectively suppresses ultrasonic frequencies, enabling accurate measurement of audio signals.

4. Elastic trapping by acoustoelastically induced transparency

Dongwoo Lee, Jeonghoon Park, Seokwoo Kim, Beomseok Oh, Xinji Piao, Namkyu Park and Junsuk Rho*
Communications Physics 8, 87, 2025 [IF: 5.8, JCR: 13.6% in Physics, Multidisciplinary]
(doi: 10.1038/s42005-025-02001-8)

3. Wide field-of-hearing metalens for aberration-free sound capture
Dongwoo Lee†, Beomseok Oh†, Jeonghoon Park, Seong-Won Moon, Kilsoo Shin, Sea-Moon Kim and Junsuk Rho*
Nature Communications 15, 3044, 2024  [IF: 15.7, JCR: 7% in Multidisciplinary Sciences]
(doi: 10.1038/s41467-024-47050-9)

Coma aberration-free wide-angle acoustic metalens
In this work, we introduce a new concept: the "field-of-hearing," as a counterpart of "field-of-view" in optics. It is well known that achieving a wide angular response in single-layer metalenses is a formidable challenge. By harnessing perfect acoustic symmetry conversion, we successfully realize an off-axis aberration-free metalens with a wide field-of-hearing.

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2. Engineering metalenses for planar optics and acoustics
Beomseok Oh†, Kyungtae Kim†, Dongwoo Lee† and Junsuk Rho*
Materials Today Physics 39, 101273, 2023
[IF: 9.7, JCR: 10.4% in Physics, Applied]  (doi: 10.1016/j.mtphys.2023.101273)

1.  An improved analytic model for designing the polymer-composite stepped-plate transducer using the modified Mindlin plate theory
Beomseok Oh, Chayeong Kim, Dongwoo Lee, Junsuk Rho* and Wonkyu Moon*
Ultrasonics 131, 106933, 2023 [IF: 4.1, JCR: 11% in Acoustics]  (doi: 10.1016/j.ultras.2023.106933)

Stepped-plate parametric array loudspeakers
Parametric array (PA) is a nonlinear acoustic phenomenon that generates directional audio by using two high-frequency ultrasounds. Traditional PA loudspeakers (PALs) use multiple radiator units, making them expensive. We have developed cost-effective PALs by incorporating polymer-composite stepped plates with a single-body piezoelectric ultrasonic transducer.