Awards/Grants

The Database Society of Japan (DBSJ) Kambayashi Young Researcher Award (2025) (link)
KDD 2024 Student Travel Award
SIGMOD Student Travel Grant for the WSDM 2024
Osaka University Fellowship for Cross-disciplinary Innovation (2023-)
Japan Student Services Organization (JASSO) Student Loan, Exemption (2023)
DEIM 2023 Student Presentation Award

Internatioanl Conference Papers

Kohei Obata, Taichi Murayama, Zheng Chen, Yasuko Matsubara, Yasushi Sakurai. “Disentangled Mode-Specific Representations for Tensor Time Series via Contrastive Learning”. PAKDD’25. (to appear)

Kohei Obata, Koki Kawabata, Yasuko Matsubara, Yasushi Sakurai. “Mining of Switching Sparse Networks for Missing Value Imputation in Multivariate Time Series”. Proceedings of the 30th ACM SIGKDD Conference on Knowledge Discovery and Data Mining (KDD ’24), August 25–29, 2024, Barcelona, Spain. (doi: 10.1145/3637528.3671760, github)
Kohei Obata, Koki Kawabata, Yasuko Matsubara, Yasushi Sakurai. “Dynamic Multi-Network Mining of Tensor Time Series”. Proceedings of the ACM Web Conference 2024 (WWW ’24, Oral Session), May 13–17, 2024, Singapore. Acceptance Rate for Oral Session: 192/2008, 9.6% (doi: 10.1145/3589334.3645461, github)
Kohei Obata. “Gaussian Graphical Model-Based Clustering of Time Series Data”. Proceedings of the 17th ACM International Conference on Web Search and Data Mining (WSDM ‘24), March 4–8, 2024, Merida, Mexico, pp. 8-12. (doi: 10.1145/3616855.3635728)

Kohei Obata. “Automatic Time-Series Clustering via Network Inference”. 47th International Conference on Very Large Data Bases (VLDB) PhD workshop, September 5, 2022, Sydney, Australia. (link)

Kohei Obata, Koki Kawabata, Yasuko Matsubara, Yasushi Sakurai. “Multivariate Time Series Imputation Method based on Sparse Network”. IPSJ Transactions on Databases (TOD) , April 2025. (to appear)

Kohei Obata, Yasuko Matsubara, Koki Kawabata, Kota Nakamura, Yasushi Sakurai. “Automatic Network Structure-based Clustering of Multivariate Time Series”. IPSJ Transactions on Databases (TOD) Vol.16, No.1, 1-13, January 2023. (link)

Kohei Obata, Koki Kawabata, Yasuko Matsubara, Yasushi Sakurai “時系列テンソルデータのための将来予測”. DEIM Forum 2023, March 5–9, 2023, Gifu, Japan. (link)