I am currently a postdoctoral researcher in Applied Mathematics at Harvard, working with Prof. L. Mahadevan. Previously, I completed my Ph.D. in Mechanical Engineering at Seoul National University under the supervision of Prof. Ho-Young Kim.

My research broadly explores the nonlinear dynamics and physics of soft matter, with particular interests in:

• Nonlinear dynamics (irregular rolling)
• Singularities (e.g., paper folding and crumpling)
• Geometry and topology (entanglement, tentacle robots, irregular rolling)
• Controllability of soft structures (web robots, tentacle robots)
• Friction and contact in soft systems (entanglement, dynamic Signorini problems)
• Collective behavior (entanglement, tentacle robots)
  — and just about everything else that bends, twists, or entangles, collectively.

Publications

*: Co-first authors

Phase transitions in rolling of irregular cylinders and spheres
Daoyuan Qian, YJ, L. Mahadevan
Proceedings of the National Academy of Sciences 122, e2417161122 (2025)

Entanglement transition in rod packings
YJ, Thomas Plumb-Reyes, Hao-Yu Greg Lin, L. Mahadevan
Proceedings of the National Academy of Sciences 122, e2401868122 (2025)

Active entanglement enables stochastic, topological grasping
Kaitlyn Becker, Clark Teeple, Nicholas Charles, YJ, Daniel Baum,
James C. Weaver, L. Mahadevan, Robert Wood
Proceedings of the National Academy of Sciences 119, e2209819119 (2022)

Thermodynamics of hygroresponsive soft engines: Cycle analysis and work ratio
Beomjune Shin, YJ, Munkyeong Choi, Ho-Young Kim
Physical Review Applied 18, 044061 (2022)

Evaporative capillary rise
Jungtaek Kim, YJ, Ho-Young Kim
Physical Review Fluids 7, L032001 (2022)

Soft artificial electroreceptors for non-contact spatial perception
W. J. Song, Y. Lee, YJ*, Y.-W. Kang, J. Kim, J.-M. Park, Y.-L. Park, H.-Y. Kim, J.-Y. Sun
Science Advances 7, sciadv.abg9203 (2021)

Avian mud nest architecture by self-secreted saliva
YJ, Sohyun Jung, Sang-im Lee, Wongjung Kim, Ho-Young Kim
Proceedings of the National Academy of Sciences 118, e2018509118 (2021)

Ionic spiderwebs
Y. Lee, W. J. Song, YJ, H. You, M.-Y. Kim, H.-Y. Kim, J.-Y. Sun
Science Robotics 5, eaaz5405 (2020)

Optimal diameter reduction ratio of acinar airways in human lungs
K. Park*, YJ, T. Son, Y.-J. Cho, N. L. Jeon, W. Kim, H.-Y. Kim
PLOS ONE 14, e0218947 (2019)

Poro-elasto-capillary wicking of cellulose sponges
J. Ha, J. Kim, YJ, G. Yun, D.-N. Kim, H.-Y. Kim
Science Advances 4, eaao7051 (2018)

Capillarity ion concentration polarization as spontaneous desalting mechanism
S. Park, YJ, S. Y. Son, I. Cho, Y. Cho, H. Lee, H.-Y. Kim, S. J. Kim
Nature Communications 7, 11223 (2016)

Three-dimensional point spread function of surface plasmon-coupled emission microscopy
YJ, Euiheon Chung
Proceedings of SPIE, Nano-Bio Sensing, Imaging, and Spectroscopy, 88790D (2013)

Media

🪺 How do bird nests stay together?
🏀 Getting the ball rolling.
🦑 This robotic tentacle gripper is gentle, practical, and terrifying.
🦑 Bizarre Tentacle Robot Looks Like It Emerged From ‘The Matrix’.
🦑 This spooky robot uses inflatable tentacles to grab delicate items.
🌲 New Models Expand Thermodynamics to Humidity-Driven Engines That Mimic Plants.
🐟 가오리 피부가 ‘힌트’… 눈 감고도 사물 감지하는 센서 개발
🛖 제비 무게 100배 견디는 제비집의 비밀은 ‘침’
🕸️ Artificial spider web gets an ionic boost
🧽 An absorbing study on the maths of sponges

Experience

2021-Present. Postdoctoral Fellow.
Harvard School of Engineering and Applied sciences, Cambridge, MA, USA.
Research: Control/design of soft matter under topological/frictional constraints.
Supervisor: Prof. Lakshminarayanan Mahadevan

2020-2021. Postdoctoral Fellow.
Rowland institute, Harvard University, Cambridge, MA, USA.
Research: Fluid dynamics of textured surfaces (e.g., shark skin) for drag reduction.
Supervisor: Dr. Shabnam Raayai-Ardakani

2019-2020. Postdoctoral Fellow.
Department of Mechanical Engineering, Seoul National University, Seoul, South Korea.
Research: Structural optimization in animal architectures.
Supervisor: Prof. Ho-Young Kim

Education

2014-2019 PhD in Mechanical Engineering.
Seoul National University, Seoul, South Korea.
Thesis: Optimal control/design principles in biological transport systems. Supervisor: Prof. Ho-Young Kim

2012-2014 MS in Biomedical Engineering.
Gwangju Institute of Science and Technology, Gwangju, South Korea.
Thesis: Statistical optics for biomedical applications.
Supervisor: Prof. Euiheon Chung

2008-2012 BS in Mechanical engineering.
Pohang university of Science and Technology, Pohang, South Korea.