CV

Education

• B.S. in Computer Science, Wake Forest University, 2013-16
• M.S. in Computer Science, Wake Forest University, 2016-18
• Ph.D in Computational Science and Engineering, College of Computing, Georgia Institute of Technology, 2018-23 (expected)

Work experience

• Summer 2015: Intern
  • NASA and Caltech’s Jet Propulsion Laboratory (JPL)
  • Developed work flows for physical ocean data visualization and processing
• Summer 2016: REU Fellow at University of Massachusetts at Amherst
  • Conducted research on Indoor Localization Problem. Determining the location of mobile devies in a building using Wi-Fi signal strengths.
• Graduate Research Assistant, Wake Forest U. 2016-18
  • Conducted research on Tensor Decompositions. Developed parallel algorithms for shared and distributed memory systems.
  • Explored applications to Neuroimaging.
  • Advised by Pr. Grey Ballard
• Summer 2019: Astro Intern at Oak Ridge National Labs
  • Worked on parallel and distrubted algorithms for Nonnegative Matrix Factorization
  • Advised by Dr. Ramakrishnan Kannan
• Summer 2021 and 2022: Berkeley Lab Summer Intern
  • Worked on developing randomized sampling algorithms for training Graph Neural Networks in Pytorch and Pytorch Geometric
  • Advised by Pr. Aydın Buluç

Publications

Dynamic functional connectivity and individual differences in emotions during social stress

Tobia, M. J., Hayashi, K., Ballard, G., Gotlib, I. H., & Waugh, C. E. (2017). Dynamic functional connectivity and individual differences in emotions during social stress. Human Brain Mapping, 38(12), 6185–6205. https://doi.org/10.1002/hbm.23821

Shared-Memory Parallelization of MTTKRP for Dense Tensors

Hayashi, Koby. (2018). "Shared-Memory Parallelization of MTTKRP for Dense Tensors." Proceedings of the 23rd ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming.

Parallel Nonnegative CP Decomposition of Dense Tensors

G. Ballard, K. Hayashi and K. Ramakrishnan, "Parallel Nonnegative CP Decomposition of Dense Tensors," 2018 IEEE 25th International Conference on High Performance Computing (HiPC), Bengaluru, India, 2018, pp. 22-31, doi: 10.1109/HiPC.2018.00012.

Hypergraph Random Walks, Laplacians, and Clustering

Koby Hayashi, Sinan G. Aksoy, Cheong Hee Park, and Haesun Park. 2020. Hypergraph Random Walks, Laplacians, and Clustering. In Proceedings of the 29th ACM International Conference on Information & Knowledge Management (CIKM20). Association for Computing Machinery, New York, NY, USA, 495–504. https://doi.org/10.1145/3340531.3412034

Distributed-Memory Parallel Symmetric Nonnegative Matrix Factorization

S. Eswar, K. Hayashi, G. Ballard, R. Kannan, R. Vuduc and H. Park, "Distributed-Memory Parallel Symmetric Nonnegative Matrix Factorization," SC20: International Conference for High Performance Computing, Networking, Storage and Analysis, Atlanta, GA, USA, 2020, pp. 1-14, doi: 10.1109/SC41405.2020.00078.

PLANC: Parallel Low Rank Approximation with Non-negativity Constraints

Srinivas Eswar, Koby Hayashi, Grey Ballard, Ramakrishnan Kannan, Michael A. Matheson, and Haesun Park. 2021. PLANC: Parallel Low-rank Approximation with Nonnegativity Constraints. ACM Trans. Math. Softw. 47, 3, Article 20 (September 2021), 37 pages. https://doi.org/10.1145/3432185

Skew Symmetric Adjacency Matrices for Clustering Directed Graphs

K. Hayashi, S. G. Aksoy and H. Park, "Skew-Symmetric Adjacency Matrices for Clustering Directed Graphs," 2022 IEEE International Conference on Big Data (Big Data), Osaka, Japan, 2022, pp. 555-564, doi: 10.1109/BigData55660.2022.10020413.

Talks

Distributed Memory Parallel Symmetric Nonnegative Matrix Factorization

September 17, 2020

Talk at Department of Computer Sciecne, UT Austin, Austin, Texas

Teaching

TA for Numerical Linear Algebra

Awards and Honors

• Computational Science Graduate Fellowship 2019-2023. Four years financial support covering full stipend, tuition and fees for PhD studies for 4 years. (https://www.krellinst.org/csgf/)
• Research Assistantship 2016-2018 Wake Forest University. Tuition and Stipend for Masters studies in Computer Science.
• NSF Travel Grant, PPoPP 2018
• ACM SIGIR Student Travel Grant, CIKM 2020
• Magna Cum Laude and Honors in Computer Science Wake Forst University 2016
• IEEE Student Travel Award, ICBD 2022