Prof. Hongki Jo Profile

Prof. Hongki Jo

Assistant Professor at The Univ. of Arizona

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Author

Publications (25)

Proceedings Article | 9 May 2024 Presentation + Paper

Performance evaluation of flexible capacitive sensors on non-uniform surfaces

Emmanuel Ogunniyi, Han Liu, John White, Austin R. Downey, Simon Laflamme, Jian Li, Caroline Bennett, William Collins, Hongki Jo, Paul Ziehl

Proceedings Volume 12949, 1294916 (2024) https://doi.org/10.1117/12.3010959

KEYWORDS: Sensors, Surface finishing, Signal to noise ratio, Transducers, Capacitors, Structural health monitoring, Structural monitoring, Capacitance

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The use of strain gauges is foundational to structural health monitoring, allowing infrastructure to continuously observe strain, infer stress, and potentially detect fatigue/fracture cracks. However, traditional strain gauges have drawbacks. In addition to being costly, a single-element strain gauge will only detect strain in a single direction and must be mounted on smooth surfaces to ensure good adhesion. Soft Elastomeric Capacitors (SECs) have been proposed as a low-cost alternative to traditional strain gauges while allowing for a broader range of applications. They are flexible and can be modeled with different dimensions based on the monitored structure. Each SEC consists of three layers; the two outer layers act as electrodes and are made of a styrene-ethylene-butylene-styrene polymer in a matrix with carbon black. The inner (dielectric) layer comprises titanium oxide in a matrix with SEBS. The use of the SECs is not limited by the geometry of the surface being monitored, and it can, therefore, be adhered to a variety of surfaces as its flexibility allows it to conform to the irregularity and complexity of the monitored structure. The change experienced by a structure will correlate directly to the change in capacitance observed across the sensor, which can be used to predict the monitored structure’s state. While SECs have been studied for applications on various materials, experiments have been limited to adhering the sensor to smooth surfaces. However, concrete structures have various surface finishes that are not uniform, often deriving from an architect’s aesthetic desire. This work tests a corrugated SEC through compression tests on concrete samples with different surface finishing to investigate the effect of surface finishing on the SEC-measured strain. Each concrete sample is subjected to loading by a dynamic testing system, and the data collected from the SEC are compared to off-the-shelf resistive strain gauges. The results show that the performance of the cSEC on the different surfaces is not hindered by different concrete finishes, where a high signal-to-noise ratio of 21 dB and low mean absolute error of 22 μϵ is seen on the concrete specimen with a rough concrete surface. The strain metrics and surface effect on SEC performance are discussed.

Proceedings Article | 18 April 2023 Presentation + Paper

Actively managed battery degradation of wireless sensors for structural health monitoring

Tahsin Afroz Hoque Nishat, Jong-Hyun Jeong, Hongki Jo, Qiang Zhou, Jian Liu

Proceedings Volume 12486, 124860Z (2023) https://doi.org/10.1117/12.2658497

KEYWORDS: Wireless sensors, Energy efficiency, System identification, Batteries, Sensor networks, Sensors, Structural health monitoring, Mode shapes, Machine learning, Solar energy, Bridges, Power consumption

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Proceedings Article | 18 April 2023 Paper

Soft elastomeric capacitors with an extended polymer matrix for strain sensing on concrete

Emmanuel Ogunniyi, Han Liu, Austin R. Downey, Simon Laflamme, Jian Li, Caroline Bennett, William Collins, Hongki Jo, Paul Ziehl

Proceedings Volume 12486, 1248618 (2023) https://doi.org/10.1117/12.2658568

KEYWORDS: Capacitance, Sensors, Capacitors, Polymers, Digital image correlation, Transducers, Electrodes, Dielectrics, Structural sensing, Structural health monitoring, Strain analysis

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Surface strain sensors, such as linear variable differential transformers, fiber Bragg gratings, and resistive strain gauges, have seen significant use for monitoring concrete infrastructure. However, spatial monitoring of concrete structures using these sensor systems is limited by challenges in the surface coverage provided by a specific sensor or issues related to mounting and maintaining numerous mechanical sensors on the structure. A potential solution to this challenge is the deployment of large-area electronics in the form of a sensing skin to provide complete coverage of a monitored area while being simple to apply and maintain. Along this line of effort, networks constituted of soft elastomeric capacitors have been deployed to monitor strain on steel and composite structures. However, using soft elastomeric capacitors on concrete surfaces has been challenging due to the electrical coupling between the sensors and concrete, which amplifies transduced strain signals obtained from the soft elastomeric capacitors. In this work, the authors investigate the isolation of the soft elastomeric capacitors from the concrete by extending the styrene-block-ethylene-co-butylene-block-styrene matrix of the soft elastomeric capacitors to include a decoupling layer between the electrode and the concrete. Experimental investigations are carried out on concrete specimens for which the soft elastomeric capacitor is adhered to with a thin layer of off-the-shelf epoxy and then loaded on the dynamic testing system to monitor strain provoked on the concrete samples. The results presented here demonstrate the viability of the electrically isolated soft elastomeric capacitors for monitoring strain on concrete structures. Initial comparisons between un-isolated and electrically isolated soft elastomeric capacitors showed that the nominal capacitance of the soft elastomeric capacitor is significantly lowered by adding an isolation layer of SEBS. Furthermore, strain results for the soft elastomeric capacitors are compared to ones from a resistive strain gauge and digital image correlation. The data obtained is significant for modifying soft elastomeric capacitors with the anticipation for future use on concrete structures.

Proceedings Article | 18 April 2022 Presentation + Paper

Long-term field monitoring of fatigue cracks for steel bridges with wireless large-area strain sensors

Sdiq Anwar Taher, Jian Li, Jong-Hyun Jeong, Simon Laflamme, Hongki Jo, Caroline Bennett, William Collins, Han Liu, Austin Downey, Mona Shaheen

Proceedings Volume 12046, 1204604 (2022) https://doi.org/10.1117/12.2613072

KEYWORDS: Sensors, Bridges, Data storage, Capacitance, Wavelets, Remote sensing, Clouds, Structural health monitoring, Continuous wavelet transforms, Strain analysis, Wireless communications, Structural sensing, Smart structures, Damage detection

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Proceedings Article | 22 March 2021 Presentation + Paper

Monitoring impact damage in composites with large area sensing skins

Alexander Vereen, Austin Downey, Subramani Sockalingham, Paul Ziehl, Simon LaFlamme, Jian Li, Hongki Jo

Proceedings Volume 11591, 115911Q (2021) https://doi.org/10.1117/12.2582572

KEYWORDS: Sensors, Capacitors, Skin, Composites, Glasses, Capacitance, Sensor networks, Nondestructive evaluation, Inspection, Head

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The effect of low energy impacts can seriously impair the operational life span of composites in the field. These low-energy impacts can induce a permanent loss in the toughness of the composite without any visible indication of the material’s compromise. The detection of this damage utilizing nondestructive inspection requires dense measurements over much of the surface and has been traditionally achieved by removing the part from service for advanced imaging techniques. While these methods can accurately diagnose the damage inflicted internally by the impacts, they accrue non-trivial opportunity costs while the structure is inspected. To enable the capabilities of in-service monitoring of the composite, the novel soft elastomeric capacitor was investigated as a sensing solution. The sensor is made of three layers comprised of a styrene-ethylene-butylene-styrene (SEBS) matrix, a commercially available elastomer. These layers consist of a titania filled center layer that forms the dielectric of the capacitor and two highly conductive outer layers doped with carbon black. This simple formation allows for a capacitor that has extremely robust mechanical properties. The soft elastomeric capacitor functions by taking up deformations on the surface of the composite that is transduced into a measurable change in capacitance. This study provides an electro-mechanical model for impact damage and experimentally investigates the efficacy of these sensors for use in damage detection given their promising characteristics; that being that the sensor geometry can be arbitrarily large allowing for much fewer sensors than traditional sensor networks employed for this task at a much lower cost than installing traditional in-situ sensing solutions. To investigate these properties a set of impact trials were undertaken on a drop tower using small samples of glass fiber reinforced plate, of random orient and short fiber, with a soft elastomeric capacitor mounted directly opposite the impact site. The impactor head was only allowed one contact with the sample before being intercepted. The testing range for the samples ranged from well below the yield strength of the glass fiber reinforced plate to the ultimate strength of the plate. Experimental results reported a square root relation between the impact energy given to the plate when inducing plastic deformations and the sensor’s measured change in capacitance.

Proceedings Article | 22 March 2021 Presentation + Paper

Experimental validation of textured sensing skin for fatigue crack monitoring

Han Liu, Simon Laflamme, Jian Li, Caroline Bennett, William Collins, Austin Downey, Hongki Jo

Proceedings Volume 11591, 115911R (2021) https://doi.org/10.1117/12.2582592

KEYWORDS: Skin, Sensors, Yield improvement, Thin films, Numerical analysis, Capacitors, Capacitance

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Proceedings Article | 27 March 2018 Presentation + Paper

Heterogeneous data fusion for impact force identification in truss structures

Muhammad Saleem, Hongki Jo

Proceedings Volume 10598, 105981X (2018) https://doi.org/10.1117/12.2296763

KEYWORDS: Error analysis, Sensors, Filtering (signal processing), Data fusion, Statistical analysis, Civil engineering, Electronic filtering, Genetic algorithms, Composites, Modeling

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Proceedings Article | 27 March 2018 Presentation + Paper

Dense capacitive sensor array for monitoring distortion-induced fatigue cracks in steel bridges

Xiangxiong Kong, Jian Li, William Collins, Caroline Bennett, Hongki Jo, Jong-Hyun Jeong, Simon Laflamme

Proceedings Volume 10598, 105980Q (2018) https://doi.org/10.1117/12.2296592

KEYWORDS: Bridges, Sensors, Capacitors, Skin, Data acquisition, Capacitance, Structural health monitoring, Lithium, Civil engineering, Safety

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Proceedings Article | 27 March 2018 Presentation + Paper

Flood fragility analysis of instream bridges

Touhid Ahamed, Jaeho Shim, Hongki Jo, Jennifer Duan

Proceedings Volume 10598, 1059826 (2018) https://doi.org/10.1117/12.2296782

KEYWORDS: Bridges, Floods, Reliability, MATLAB, Corrosion, 3D modeling, Structural analysis, Civil engineering, Inspection

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Proceedings Article | 27 March 2018 Presentation + Paper

Capacitance-based wireless strain sensor development

Jong-Hyun Jeong, Jian Xu, Hongki Jo, Jian Li, Xiangxiong Kong, William Collins, Caroline Bennett, Simon Laflamme

Proceedings Volume 10598, 105980S (2018) https://doi.org/10.1117/12.2296716

KEYWORDS: Capacitance, Wheatstone bridges, Capacitors, Structural health monitoring

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Proceedings Article | 12 April 2017 Paper

A robust signal processing method for quantitative high-cycle fatigue crack monitoring using soft elastomeric capacitor sensors

Xiangxiong Kong, Jian Li, William Collins, Caroline Bennett, Simon Laflamme, Hongki Jo

Proceedings Volume 10168, 101680B (2017) https://doi.org/10.1117/12.2260364

KEYWORDS: Signal processing, Capacitors, Sensors, Electronics, Structural health monitoring, Bridges, Capacitance, Performance modeling, Data acquisition, Civil engineering

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Proceedings Article | 20 April 2016 Paper

Real-time image processing for non-contact monitoring of dynamic displacements using smartphone technologies

Jae-Hong Min, Nikolas Gelo, Hongki Jo

Proceedings Volume 9803, 98031B (2016) https://doi.org/10.1117/12.2219418

KEYWORDS: Structural health monitoring, Image processing, Real time image processing, Sensor networks, Graphics processing units, High speed cameras, Cameras, Machine vision, Computer vision technology, Optical filters, Image filtering, OpenGL, Information operations, Sensors, Target detection

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Proceedings Article | 20 April 2016 Presentation + Paper

High-sensitivity strain visualization using electroluminescence technologies

Jian Xu, Hongki Jo

Proceedings Volume 9803, 98030T (2016) https://doi.org/10.1117/12.2218545

KEYWORDS: Visualization, Electroluminescence, Structural health monitoring, Civil engineering, Sensors, Wheatstone bridges

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Proceedings Article | 20 April 2016 Paper

Practical application of RINO, a smartphone-based dynamic displacement sensing application for wind tunnel tests

Seung-Woo Lee, Jong-Hyun Jeong, Kyle Knez, Jae-Hong Min, Hongki Jo

Proceedings Volume 9803, 98032X (2016) https://doi.org/10.1117/12.2219404

KEYWORDS: Wind measurement, Structural health monitoring, Sensors, Visual optics, Sensor performance, Cameras, Image processing, Position sensors, Imaging systems, Video acceleration, Bridges, Optical filters, Information operations, Aerodynamics, Data modeling, Data acquisition

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Proceedings Article | 20 April 2016 Paper

Multi-metric strain estimation at unmeasured locations of plate structures using augmented Kalman filter

Dyan Melvin, Hongki Jo, Babak Khodabandeloo

Proceedings Volume 9803, 980348 (2016) https://doi.org/10.1117/12.2219203

KEYWORDS: Filtering (signal processing), Sensors, Failure analysis, Model-based design, Structural health monitoring, Bridges, Time metrology, Finite element methods, Data analysis, Sensing systems, Error analysis, Matrices, Civil engineering

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Proceedings Article | 10 April 2014 Paper

Multi-metric model-based structural health monitoring

Hongki Jo, B. Spencer

Proceedings Volume 9061, 90611F (2014) https://doi.org/10.1117/12.2045126

KEYWORDS: Filtering (signal processing), Error analysis, Structural health monitoring, Sensors, Model-based design, Bridges, Safety, Matrices, Inspection, Sensor technology

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Proceedings Article | 19 April 2013 Paper

Automated wireless monitoring system for cable tension using smart sensors

Sung-Han Sim, Jian Li, Hongki Jo, Jongwoong Park, Soojin Cho, Billie Spencer, Chung-Bang Yun

Proceedings Volume 8692, 86922B (2013) https://doi.org/10.1117/12.2009552

KEYWORDS: Bridges, Sensors, Smart sensors, Sensor networks, Structural health monitoring, Antennas, Data processing, Solar cells, Connectors, Data transmission

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Proceedings Article | 3 April 2012 Paper

Preliminary study of low-cost GPS receivers for time synchronization of wireless sensors

R. Kim, T. Nagayama, H. Jo, B. Spencer

Proceedings Volume 8345, 83451A (2012) https://doi.org/10.1117/12.915394

KEYWORDS: Global Positioning System, Receivers, Structural health monitoring, Sensors, Clocks, Electronic filtering, Sensor networks, Smart sensors, Error analysis, Linear filtering

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Proceedings Article | 3 April 2012 Paper

Design and validation of high-precision wireless strain sensors for structural health monitoring of steel structures

Hongki Jo, JongWoong Park, B. Spencer, Hyung-Jo Jung

Proceedings Volume 8345, 834518 (2012) https://doi.org/10.1117/12.915392

KEYWORDS: Wheatstone bridges, Bridges, Sensors, Structural health monitoring, Calibration, Temperature metrology, Resistors, Amplifiers, Magnetic sensors, Resistance

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Proceedings Article | 18 April 2011 Paper

Full-scale decentralized damage identification using wireless smart sensors

Shinae Jang, Sung-Han Sim, Hongki Jo, Billie Spencer

Proceedings Volume 7981, 79814W (2011) https://doi.org/10.1117/12.881160

KEYWORDS: Bridges, Structural health monitoring, Sensors, Damage detection, Smart sensors, System identification, Head, Environmental sensing, Software development, Solar cells

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Proceedings Article | 13 April 2011 Paper

Hybrid wireless smart sensor network for full-scale structural health monitoring of a cable-stayed bridge

Hongki Jo, Sung-Han Sim, Kirill Mechitov, Robin Kim, Jian Li, Parya Moinzadeh, B. Spencer, Jong Woong Park, Soojin Cho, Hyung-Jo Jung, Chung-Bang Yun, Jennifer Rice, Tomonori Nagayama

Proceedings Volume 7981, 798105 (2011) https://doi.org/10.1117/12.880513

KEYWORDS: Sensors, Structural health monitoring, Bridges, Smart sensors, Sensor networks, Neodymium, Environmental monitoring, Environmental sensing, Data communications, Data processing

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Proceedings Article | 1 April 2010 Paper

Feasibility study of wind generator for smart wireless sensor node in cable-stayed bridge

Jong-Woong Park, Hyung-Jo Jung, Hongki Jo, Shinae Jang, Billie Spencer

Proceedings Volume 7647, 764747 (2010) https://doi.org/10.1117/12.853600

KEYWORDS: Sensors, Bridges, Solar energy, Structural health monitoring, Wind energy, Solar cells, Energy harvesting, Wind measurement, Resistance, Wind turbine technology

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Proceedings Article | 1 April 2010 Paper

Decentralized bridge health monitoring using wireless smart sensors

S. Jang, S. Sim, H. Jo, B. Spencer

Proceedings Volume 7647, 76473I (2010) https://doi.org/10.1117/12.847527

KEYWORDS: Structural health monitoring, Sensors, Smart sensors, Damage detection, Bridges, System identification, Correlation function, Data processing, Matrices, Head

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Proceedings Article | 1 April 2010 Paper

Development of high-sensitivity accelerometer board for structural health monitoring

Hongki Jo, Jennifer Rice, Billie Spencer, Tomonori Nagayama

Proceedings Volume 7647, 764706 (2010) https://doi.org/10.1117/12.848905

KEYWORDS: Sensors, Structural health monitoring, Smart sensors, Interference (communication), Sensor networks, Magnesium, Analog electronics, Power supplies, Microelectromechanical systems, Signal to noise ratio

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Proceedings Article | 1 April 2010 Paper

Structural health monitoring system of a cable-stayed bridge using a dense array of scalable smart sensor network

Soojin Cho, Shin Ae Jang, Hongki Jo, Kirill Mechitov, Jennifer Rice, Hyung-Jo Jung, Chung-Bang Yun, Billie Spencer, Tomonori Nagayama, Juwon Seo

Proceedings Volume 7647, 764707 (2010) https://doi.org/10.1117/12.852272

KEYWORDS: Bridges, Smart sensors, Structural health monitoring, Sensors, Sensor networks, Wind measurement, Data communications, Energy harvesting, Solar cells, Head

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Showing 5 of 25 publications

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