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Your search keyword '"Lee, Taehwa"' showing total 169 results
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169 results on '"Lee, Taehwa"'

10. Robust acoustic directional sensing enabled by synergy between resonator-based sensor and deep learning.

Author

Yu, Ziqi, Li, Xiaopeng, Jung, Hojung, Harada, Masahiro, Prokhorov, Danil, and Lee, Taehwa

Abstract

We demonstrate enhanced acoustic sensing arising from the synergy between resonator-based acoustic sensor and deep learning. We numerically verify that both vibration amplitude and phase are enhanced and preserved at and off the resonance in our compact acoustic sensor housing three cavities. In addition, we experimentally measure the response of our sensor to single-frequency and siren signals, based on which we train convolutional neural networks (CNNs). We observe that the CNN trained by using both amplitude and phase features achieve the best accuracy on predicting the incident direction of both types of signals. This is even though the signals are broadband and affected by noise thought to be difficult for resonators. We attribute the improvement to a complementary effect between the two features enabled by the combination of resonant effect and deep learning. This observation is further supported by comparing to the CNNs trained by the features extracted from signals measured on reference sensor without resonators, whose performances fall far behind. Our results suggest the advantage of this synergetic approach to enhance the sensing performance of compact acoustic sensors on both narrow- and broad-band signals, which paves the way for the development of advanced sensing technology that has potential applications in autonomous driving systems to detect emergency vehicles. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Understanding social innovation activities for energy transition: Evidence from experiences of social innovation agents in South Korea.

Author

Kim, Gyuhwan and Lee, Taehwa

Subjects
SOCIAL innovation, CITIZEN attitudes, ATTITUDE change (Psychology), ALTERNATIVE fuels, POLITICAL participation, TECHNOLOGICAL innovations
Abstract

Even though social innovations activities have been garnering global interest, their implications on energy transition remain unclear. In this study, we aimed to define social innovation activities that can support energy transition. We interviewed 19 social innovation agents, and the grounded theory (GT) method was applied to define the social innovation activities applicable for energy transition through inductive reasoning. Our results revealed that social innovation activities for energy transition could be defined as the entire interaction process between the pragmatic actions of agents and the participation of citizens. Notably, social innovation activities for energy transition could increase citizen participation and help economies to transition from conventional to alternative energy production and use systems. Thus, these activities lead to significant changes in the behaviors and attitudes of citizens, which are the prime factors when incorporating a subsequent structural change. Our study can provide a reliable framework to understand social innovation activities for energy transition and guide both agents and policy practitioners in decision-making, to improve and smoothen energy transition in South Korea. [ABSTRACT FROM AUTHOR]

Published
2023
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31. A Tactile Emotional Interface for Instant Messenger Chat

Author

Shin, Heesook, Lee, Junyoung, Park, Junseok, Kim, Youngjae, Oh, Hyunjoo, Lee, Taehwa, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Smith, Michael J., editor, and Salvendy, Gavriel, editor

Published
2007
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37. Passive Cavitation Mapping by Cavitation Source Localization from Aperture-Domain Signals – Part 1: Theory and Validation Through Simulations

Author

Telichko, Arsenii V., Lee, Taehwa, Jakovljevic, Marko, and Dahl, Jeremy J.

Subjects
Microbubbles, Sound, Acoustics, Article, Algorithms, Ultrasonography
Abstract

Passive cavitation mapping (PCM) algorithms for diagnostic ultrasound arrays based on time exposure acoustics (TEA) exhibit poor axial resolution, which is in part due to the diffraction-limited point spread function of the imaging system and poor rejection by the delay-and-sum beamformer. Here, we adapt a method for speed of sound estimation to be utilized as a cavitation source localization (CSL) approach. This method utilizes a hyperbolic fit to the arrival times of the cavitation signals in the aperture domain, and the coefficients of the fit are related to the position of the cavitation source. Wavefronts exhibiting poor fit to the hyperbolic function are corrected to yield improved source localization. We demonstrate through simulations that this method is capable of accurate estimation of the origin of coherent spherical waves radiating from cavitation/point sources. The average localization error from simulated microbubble sources was 0.12±0.12 mm (0.15±0.14λ(0) for a 1.78MHz transmit frequency). In simulations of two simultaneous cavitation sources, the proposed technique had an average localization error of 0.2 mm (0.23λ(0)), while conventional time exposure acoustics (TEA) had an average localization error of 0.81 mm (0.97λ(0)). The reconstructed PCM-CSL image showed a significant improvement in resolution compared to the PCM-TEA approach.

Published
2021

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