Repository Community: null
http://hdl.handle.net/20.500.11750/171
2024-03-22T08:20:47Z
2024-03-22T08:20:47Z
가이드와이어 마이크로로봇 및 그 제작 방법
김진영
최홍수
황준선
http://hdl.handle.net/20.500.11750/48128
2024-02-29T17:40:17Z
Title: 가이드와이어 마이크로로봇 및 그 제작 방법
Author(s): 김진영; 최홍수; 황준선
Autonomous 3D positional control of a magnetic microrobot using reinforcement learning
Abbasi, Sarmad Ahmad
Ahmed, Awais
Noh, Seungmin
Gharamaleki, Nader Latifi
Kim, Seonhyoung
Chowdhury, Aparajita M. Masum Bulbul
Kim, Jin-young
Pane, Salvador
Nelson, Bradley J.
Choi, Hongsoo
http://hdl.handle.net/20.500.11750/47980
2024-03-21T00:40:29Z
2023-12-31T15:00:00Z
Title: Autonomous 3D positional control of a magnetic microrobot using reinforcement learning
Author(s): Abbasi, Sarmad Ahmad; Ahmed, Awais; Noh, Seungmin; Gharamaleki, Nader Latifi; Kim, Seonhyoung; Chowdhury, Aparajita M. Masum Bulbul; Kim, Jin-young; Pane, Salvador; Nelson, Bradley J.; Choi, Hongsoo
Abstract: Magnetic microrobots have shown promise in the field of biomedical engineering, facilitating precise drug delivery, non-invasive diagnosis and cell-based therapy. Current techniques for controlling the motion of such microrobots rely on the assumption of homogenous magnetic fields and are significantly influenced by a microrobot’s properties and surrounding environment. These strategies lack a sense of generality and adaptability when changing the environment or microrobot and exhibit a moderate delay due to independent control of the electromagnetic actuation system and microrobot’s position. To address these issues, we propose a machine learning-based positional control of magnetic microrobots via gradient fields generated by electromagnetic coils. We use reinforcement learning and a gradual training approach to control the three-dimensional position of a microrobot within a defined working area by directly managing the coil currents. We develop a simulation environment for initial exploration to reduce the overall training time. After simulation training, the learning process is transferred to a physical electromagnetic actuation system that reflects real-world intricacies. We compare our method to conventional proportional-integral-derivative control; our system is more accurate and efficient. The proposed method was combined with path planning algorithms to allow fully autonomous control. The presented approach is an alternative to complex mathematical models, which are sensitive to variations in microrobot design, the environment and the nonlinearity of magnetic systems. © 2024, The Author(s), under exclusive licence to Springer Nature Limited.
2023-12-31T15:00:00Z
Fabrication and Characterization of the Transparent PLZT-Based Piezoelectric Speaker
Lee, Younghyeon
Choi, Jong-Jin
Choi, Hongsoo
Jang, Jongmoon
http://hdl.handle.net/20.500.11750/47915
2024-02-08T16:40:13Z
2023-10-31T15:00:00Z
Title: Fabrication and Characterization of the Transparent PLZT-Based Piezoelectric Speaker
Author(s): Lee, Younghyeon; Choi, Jong-Jin; Choi, Hongsoo; Jang, Jongmoon
Abstract: The transparent piezoelectric loudspeaker has received significant attention as acoustic components for smart window system due to its lightweight, portability, and visibility. In this work, we fabricated a Lanthanum lead zirconate titanate (PLZT) ceramic disc with transparency (65% at 550 nm) and piezoelectric properties (d33 = 180 pC/N) by oxygen atmosphere sintering method. In addition, a transparent piezoelectric loudspeaker was developed by sputtering top and bottom electrode with indium tin oxide (ITO) thin film on the PLZT ceramic disc, and attaching them to Polyethylene terephthalate (PET) as a diaphragm. Applying the input voltage of 10 Vpp, the piezoelectric PLZT loudspeaker shows a frequency response of 30 to 68 dB sound pressure in the frequency range of 500 Hz to 8 kHz. This study showed that the transparent PLZT speakers could potentially be applied to future smart devices or displays. © 2023 IEEE.
2023-10-31T15:00:00Z
Characterizing the Performance of a Resonance-Based MEMS Particle Sensor with Glass Beads
Choi, Ji-Seob
Noh, Jinhong
Choi, Hongsoo
Yoon, Yong-Jin
Park, Woo-Tae
http://hdl.handle.net/20.500.11750/47724
2024-03-19T08:40:31Z
2024-02-29T15:00:00Z
Title: Characterizing the Performance of a Resonance-Based MEMS Particle Sensor with Glass Beads
Author(s): Choi, Ji-Seob; Noh, Jinhong; Choi, Hongsoo; Yoon, Yong-Jin; Park, Woo-Tae
Abstract: Fine dust measurement methods, such as weight change, beta ray measurement, light scattering, and resonance change, have been studied and used, but there is still room for improvement in terms of cost, system volume, and accuracy. In this study, we aimed to develop a low-cost, micro-scale, and highly accurate dust sensor using semiconductor processes. The sensor consists of a piezoelectric membrane with a diameter of 800µm and a thickness of 2.8µm. The resonance frequency and mode shape were measured and monitored using a Laser-Doppler-Vibrometer (LDV), and the resonance frequency shift was calculated based on the same mode shape. Vibration modes from (0,1) to (3,1) were observed within a 0–200kHz frequency bandwidth. Spherical glass beads were used to measure resonance frequency shift for additional mass ranging from 0.863 to 4.52µg. The first resonance mode (0,1) exhibited a clear proportional relationship between the resonance frequency shift and additional mass, while other modes exhibited non-proportional trends. Intriguingly, notable discrepancies in the resonance frequency shift emerged based on the spatial placement of the glass beads, even when the mass was the same. Additionally, we presented an approximate theoretical curve to portray the resonance frequency shift, which we subsequently validated against our measurement findings. This study presents a new attempt on the characterization method of piezoelectric mass sensors and provides a relatively simple and accurate analysis of the results. © 2023, The Author(s), under exclusive licence to Korean Society for Precision Engineering.
2024-02-29T15:00:00Z