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Yonghwan Moon,Jihoon Kim,Suhun Jung,Sang Kyung Kim,Jeongryul Kim,Keri Kim 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
Due to the worldwide spread of COVID-19, each government invests many human resources and money in screening tests. The spread of the virus has led to the development of robots that track the location of specimen collection or drive directly through master-slave devices by installing special equipment on patients noses to reduce the physical burden on medical staff and prevent infection during screening tests. Sampling robots proposed in previous studies have a rather complicated specimen collection process or make it impossible to collect specimens when the patient cannot wear special equipment. Therefore, we propose a deep learning-based model that predicts the nasopharyngeal specimen sampling path without additional equipment. The test bench for the collection of learning datasets was configured, and the nasopharyngeal specimen sampling path was expressed using an augmented reality marker to learn the estimated value. In addition, we add weight factors to the proposed model to compare the root mean square error of the direction vector.
Proactive strategy for long-term biological research aimed at low-dose radiation risk in Korea
Seong, Ki Moon,Kwon, TaeWoo,Park, Jina,Youn, BuHyun,Cha, Hyuk-Jin,Kim, Yonghwan,Moon, Changjong,Lee, Seung-Sook,Jin, Young Woo Informa UK (Taylor Francis) 2018 International journal of radiation biology Vol.94 No.7
An underwater parametric array source transducer composed of PZT/thin-polymer composite
Hwang, Yonghwan,Ahn, Hongmin,Nguyen, Duc-Nam,Kim, Wonho,Moon, Wonkyu Elsevier 2018 Sensors and actuators. A, Physical Vol.279 No.-
<P><B>Abstract</B></P> <P>The source transducers for parametric array (PA) sound are required to radiate the primary wave with high intensity and directivity so as to generate nonlinear interactions between strong acoustic waves at different frequencies effectively, resulting in so-called PA sound. Thickness-mode piezoelectric transducers using 1–3 lead zirconate titanate (PZT) polymer composites were used to produce wide-bandwidth PA sound due to their ability to generate high-intensity, high-frequency sound beams over a relatively wide frequency band. The small mechanical quality factor of 1–3 PZT polymer composites results in high damping of the polymer matrix leading to a transducer with relatively flat frequency response but yet decreased-power efficiency. A PZT polymer composite that can enhance the power efficiency of a PA source transducer over a wide frequency bandwidth was proposed. This is achieved by adopting thinner polymer matrix layers and PZT rods with dual resonance frequencies. A transducer demonstrated ultrasonic sound up to 197 and 203 dB (re = 1 μP) at 98 and 135 kHz, respectively. The power efficiencies were 50% at 98 kHz and 33% at 135 kHz. PA sound was successfully generated up to 150 dB (re = 1 μP) at 30 kHz with a half-power beam width of 3.4°.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Source transducer was suggested for parametric array in underwater. </LI> <LI> The source transducer is PZT/thin-polymer composite. </LI> <LI> The transducer has characteristics of wide frequency bandwidth and high radiation efficiency. </LI> </UL> </P>
Hwang, Yonghwan,Moon, Wonkyu Elsevier 2018 Applied acoustics Vol.141 No.-
<P><B>Abstract</B></P> <P>Parametric array (PA) sources generate a directional sound beam, via the PA phenomenon. Practical PA sources, such as PA loudspeakers, have high power consumption, low sound quality, and high cost. The stepped-plate transducer, which consists of a Langevin transducer, a horn, and a radiating plate with steps, can provide high-intensity sound and a highly directional sound beam in the acoustic axis. This study investigated the use of a stepped-plate transducer to make a PA source with high directivity and a wide bandwidth. A stepped-plate transducer that had two different resonance frequencies (<I>f</I> <SUB>1</SUB> = 77.5 kHz, <I>f</I> <SUB>2</SUB> = 87.4 kHz) was designed for wide bandwidth, and the three different heights of the steps on the plate (<I>t<SUB>s</SUB> </I> <SUB>1</SUB> = 2.28 mm, <I>t<SUB>s</SUB> </I> <SUB>2</SUB> = 2.14 mm, <I>t<SUB>s</SUB> </I> <SUB>3</SUB> = 2.02 mm) were intended to provide high directivity sound beams. The fabricated stepped-plate transducer demonstrated a 50 ± 3 dB sound pressure level for the difference frequency wave in the 4–19 kHz frequency range (with equalization), and 4.2–5.1° of HPBW was shown for the highly directional sound beam.</P>
High-Force Display Capability and Wide Workspace With a Novel Haptic Interface
Lee, Giuk,Hur, Sung-Moon,Oh, Yonghwan IEEE 2017 IEEE/ASME transactions on mechatronics Vol.22 No.1
<P>We present a novel haptic interface, named VirtuaPower, having a high-force display capability (FDC) and a wide workspace with a six-degree-of-freedom position measurement and FDC. The overall mechanism of VirtuaPower is designed based on a parallel pair of five-bar mechanisms supporting the end-platform. This novel mechanism enhances the high-FDC and overcomes the problem of small-size workspace, which are the pros and cons of parallel mechanisms, respectively. First, we present the conceptual design and prototype of VirtuaPower. Then, we formulate the forward kinematic and the constraint and space Jacobian. Using these formulations, we analyze two types of workspaces and FDC. In both analyses, VirtuaPower shows remarkable performances, especially in terms of its FDC, compared to other haptic interfaces having an equivalent size. In addition, we validate the static, step, and frequency responses of the force-display performance by performing experiments using the test bench of fixed end setup with a six-dimensional force/torque sensor. Finally, we evaluate the suitability of VirtuaPower as a haptic interface by realizing two types of virtual sphere walls and a virtual reality environment.</P>