Research

Sponsor: NRF (한국연구재단)

We conduct fundamental research on high-speed bearingless motors (i.e., magnetically levitated motor systems) for medium to high-power industrial applications. The research topics include 1) design of novel rotor topologies suitable for high-speed rotation, 2) design of multiphase combined windings, 3) computationally efficient electromagnetic analysis and optimization, and 4) development of power electronics and control systems.

Sponsor: KETEP (한국에너지기술평가원)
Collaborators: LG electronics, Chungnam National Univ, Soongsil Univ, Yonsei Univ, Postech, KIER

Active magnetic bearings (AMB) have been successfully deployed in advanced energy conversion systems, such HVAC chillers. Conventional AMBs use discrete sensors (e.g., eddy-current sensors) to measure the rotor's position and implement feedback controls. However, industry partners concern that sensors are prone to failure at elevated temperatures, such as in heat pumps. We are developing a sensorless control method for AMBs to eliminate the need for discrete sensors.

Sponsor: KRIT (국방기술진흥연구소)
Collaborators: Chungnam National Univ and Daejeon Technopark

Conventional helicopters use a swashplate to impose cyclic pitching on the rotor blades, thereby controlling the body's attitude and motions. For miniature drones, however, swashplate is not a favorable solution due to its large volume and mechanical complexity. We are developing a new type of magnetic actuators that can replace the function of the swashplate in a reduced volume and mechanical complexity.

Sponsor: KAIST
Collaborators: Profs. Heejin Ahn and Dasom Lee 

As a part of smart city testbed project for enhancing social acceptance of autonomous driving systems, we develop miniaturized autonomous vehicles (15:1 scale) that can communicate with the centralized controller coordinating multiple vehicles at road intersections.

Sponsor: KAIST
Collaborators: Profs. Sanha Kim, Hansohl Cho, Jeonyoon Lee

We develop element technologies for future electric mobility, such as 3D printed electric motors, carbon-reinforced high-speed rotors, hybrid magnetic circuit modeling for design optimization, and continuum electromechanics models.

Sponsor: NST (국가과학기술회)
Collaborators: KARI and KITECH

A drone propeller system typically consists of an electronic speed controller, brushless DC motor, and a propeller.  By combining model-based estimation and machine learning algorithm, we are developing a sensorless monitoring  system which can infer any damage of a drone propeller (e.g., wear or breakage) from the real-time measurement of motor voltages and currents.

Sponsors: UBC, NSERC, CFI

We developed bearingless motors (i.e., magnetically levitated motor systems) for high-speed industrial applications. The research topics include 1) design of multi-phase power electronic systems using wide-bandgap power devices and FPGA-based controllers, 2) design of novel motor topologies using magnet-free/reduced-magnet rotors and multi-phase windings, and 3) electromechanical modeling and analysis for optimal design and model-based control.

Sponsor: NSF
Collaborators: MIT, Caltech, Syracus University, University of Adelaide, LIGO Scientific Collaboration

We developed a new type of piezo-actuated deformable mirror for the laser interferometer gravitational-wave observatory (LIGO) active wavefront control. This is a system that can actively change the curvature of a mirror for mode matching between a laser beam and an optical filter cavity, thereby reducing the optical quantum noise. Since the LIGO mirrors need to be super-polished for the required surface figure, we cannot use a thin mirror (< 1mm) as in typical adaptive optics. Instead, Dr. Noh developed a novel flexure mechanism that holds a thick mirror (6mm) and applies a distributed moment on the mirror barrel with a piezo actuator.

Sponsor: NIH, Samsung Scholarship
Collaborators: MIT, Ension Inc.

We developed a bearingless blood pump whose rotor/impeller is magnetically levitated and rotated by a single stator unit. The contact-free operation reduces heat and stress imposed on the blood ow, thereby preventing hemolysis and thrombosis. A novel aspect of the pump is that the rotating body does not include permanent magnets. This reduces the unit cost of the pump head which should be disposed for each patient each time.

Sponsor: MIT Lincoln Laboratory

We developed a spherical motor that levitates and rotates a dipole-magnet rotor. The motor can generate an average reaction torque about any axis, which can be utilized to control the orientation of a satellite. This single sphere can reduce the size, weight, and power consumption of a satellite attitude control system by substituting for the conventional three momentum wheels.

Sponsor: DARPA
Collaborators: MIT Department of Biological Engineering

We developed a capacitive sensing technology providing a scalable and cost-effective way to enable continuous monitoring and closed-loop feedback control of fluid volumes in small-scale gravity-dominated wells in a variety of microfluidic applications, such as organ-on-chip platforms.

Sponsor: Samsung Scholarship
Collaborators: MIT, Boston Children's Hospital

Long-gap esophageal atresia (LGEA) is a rare-birth disorder where a baby is born with a disconnected esophagus. We developed a magnet-tipped catheter that can be inserted into the esophageal segments to stretch the tissue for tension-induced growth. A hydraulic piston is embedded at the tip of the catheter to control and measure the tension applied to the esophageal segments. The device enables less-invasive surgical correction of LGEA than the current standard method that requires multiple open-chest surgeries.

Sponsor: NRF (한국연구재단)
Collaborators: SNU Biorobotics Laboratory

We developed a 2 cm scale flea-inspired jumping robot that jumps 30times its body size. The main idea is to realize the flea's muscle structure using shape memory alloy (SMA) springs.