Hyosang Yoon

In recent years, highly sensitive pressure sensors that are flexible, biocompatible, and stretchable have attracted significant research attention in the fields of wearable electronics and smart skin. However, there has been a considerable challenge to simultaneously achieve highly sensitive, low-cost sensors coupled with optimum mechanical stability and an ultralow detection limit for subtle physiological signal monitoring devices. Targeting aforementioned issues, herein, we report the facile f

The rapid development of pressure sensors with distinct functionalities, notably, with increased sensitivity, fast response time, conformability, and a high degree of deformability, has increased the demand for wearable electronics. In particular, pressure sensors with an excellent sensitivity in the low-pressure range (<2 kPa) and a large working range simultaneously are strongly demanded for practical applications in wearable electronics. Here, we demonstrate an emerging class of solid polymer

Abstract Pressure sensors with highly sensitive and flexible characteristics have extensive applications in wearable electronics, soft robotics, human–machine interface, and more. Herein, an effective strategy is explored to enhance the sensitivity of the capacitive pressure sensor by fabricating a dielectric hybrid sponge consisting of calcium copper titanate (CaCu 3 Ti 4 O 12 , CCTO), a giant dielectric permittivity material, in polyurethane (PU). An ultrasoft CCTO@PU hybrid sponge is fabricat

Abstract On‐body strain information provides various indicators such as heart rate, physiological pulse, voice waveform, respiratory rate, and body motion status. Recent advances in wearable strain sensors using nanomaterials have significantly enhanced sensor performance with regard to sensitivity, detectable range, and response time. However, it is still challenging to obtain all types of body strain information, from small vibrations to joint movements, using one type of sensor. Herein, a ful

Abstract Recent advances in supercapacitive pressure sensors based on iontronic film have a significant capacitive response and a low detection limit due to their large capacitance change resulting from electrical double layer (EDL) and these pressure sensors are used to detect a wide range of pressure with high resolution for various applications such as prosthesis, wearable devices, and robotics. Thus, the enhancements to the EDL capacitive response are significantly important challenges for a

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

In this work, a Kalman filtering algorithm is proposed that estimates the spacecraft attitude and attitude parameters without gyroscope measurements for nanosatellites. The attitude parameters include sensor and actuator alignment, spacecraft body moment of inertia, reaction wheel moment of inertia, reaction wheel speed, and the dipole moment of the spacecraft. The new filtering formulation is based on the differential form of the rigid-body rotational dynamics, and so the body rate and the othe

We propose a new star pattern identification algorithm using the vector pattern matching technique on the celestial sphere. The proposed algorithm provides more robust identification performance in cases where the captured star images are biased from the onboard catalog star image positions. The technique is based on the approach of maximizing the target score function, which is formed by the correlation between the original and the reference star patterns on the celestial sphere.

Abstract A star tracker calibration method using star images is presented in this paper. Unlike previous works, the proposed method estimates all parameters and the attitudes at once in a single least-squares formulation for the optimal calibration, which can be easily converted to a recursive estimation form. In addition, this paper presents a method to estimate the overall star tracker performance for attitude determination from the calibration results. Since the proposed method uses star imag

As CubeSat capabilities continue to improve, many missions need high-speed communication to downlink data. Data rates using radio frequency (RF) communications are constrained by antenna size and power. Laser communications (lasercom) systems can use a much narrower beam width for a given aperture size due to having shorter wavelengths. Higher data rates can be achieved with optical communication than with RF assuming the same power level and similar efficiencies, but the primary challenge of la

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.