Hanbum Ko

I am a Ph.D. student in Artificial Intelligence at Korea University, advised by Prof. Sungwoong Kim and Prof. Sungbin Lim, as a member of the AGI Laboratory, and I received my M.S. in Artificial Intelligence from UNIST.

My research is on AI for Science — building large language models that reason about chemistry, ground themselves in molecular structure, and can be trusted on real scientific tasks.

Email  /  CV  /  Scholar  /  Github  /  LinkedIn

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Updates

2026 RetroReasoner, our reasoning LLM for strategic retrosynthesis prediction, is accepted to Findings of EMNLP 2026.
2026 MolDesignBench, our benchmark for evaluating LLM agents on scenario-grounded molecular design, is accepted to COLM 2026.
2025 Our hierarchical decomposition framework for the Steiner tree packing problem received the Best Paper Award at ICORES 2025.
2025 ReactionReasoner and Mol-LLM are both accepted to the NeurIPS 2025 Workshop on AI for Science, on chemical reaction reasoning and structure-grounded molecular LLMs.

Research

My research is on AI for Science, primarily large language models for chemistry. Three lines of work: eliciting explicit reasoning for retrosynthesis and reaction prediction; grounding multimodal LLMs in molecular structure so that molecular graphs are used rather than ignored; and building the data pipelines and benchmarks needed to train and evaluate these models on realistic tasks.

I also work on neural combinatorial optimization for industrial problems such as circuit routing and truck-and-drone delivery. In both areas I work on settings with real-world constraints — feasible solutions that are hard to find, semi-structured data, and evaluation that reflects how a model would actually be used.

First-author works are highlighted below.

RetroReasoner
RetroReasoner: A Reasoning LLM for Strategic Retrosynthesis Prediction
Hanbum Ko, Chanhui Lee, Ye Rin Kim, Rodrigo S. Hormazabal, Sehui Han, Sungbin Lim, Sungwoong Kim
Findings of EMNLP, 2026
paper

Trains an LLM to reason explicitly about strategic bond disconnections — which bond to break, and why — before proposing precursors, so a retrosynthesis prediction can be inspected rather than merely ranked.

MolDesignBench
MolDesignBench: Evaluating LLM-based Agent for Scenario-grounded Molecular Design
Yongjun Jeong, Hanbum Ko, Ye Rin Kim, Chanhui Lee, Rodrigo S. Hormazabal, Jaewan Lee, Sehui Han, Sungbin Lim, Sungwoong Kim
Conference on Language Modeling (COLM), 2026

A benchmark that places LLM agents in scenario-grounded design tasks — an objective and its constraints — and measures whether the molecules they propose actually satisfy them.

ReactionReasoner
ReactionReasoner: Towards Reasoning LLM for Chemical Reaction Prediction
Hanbum Ko, Chanhui Lee, Ye Rin Kim, Rodrigo S. Hormazabal, Sehui Han, Sungbin Lim, Sungwoong Kim
NeurIPS Workshop on AI for Science, 2025
paper

Rather than mapping reactants to products in a single pass, the model works through the transformation step by step, which helps most where pattern matching over SMILES fails.

Mol-LLM
Mol-LLM: Multimodal Generalist Molecular LLM with Improved Graph Utilization
Chanhui Lee, Hanbum Ko, Yuheon Song, Yongjun Jeong, Rodrigo S. Hormazabal, Sehui Han, Kyunghoon Bae, Sungbin Lim, Sungwoong Kim
NeurIPS Workshop on AI for Science, 2025
arXiv / openreview

Multimodal molecular LLMs are given molecular graphs but rarely use them. Molecular structure Preference Optimization (MolPO) optimizes preferences between correct and perturbed structures, so the model exploits structure and outperforms both generalist and specialist models on property and reaction prediction.

Steiner tree packing
Hierarchical Decomposition Framework for Steiner Tree Packing Problem
Hanbum Ko, Minu Kim, Honglak Lee, Sungbin Lim, Sungryull Sohn, et al.
ICML Workshop on Sampling and Optimization in Discrete Space (SODS), 2023  /  ICORES, 2025  (Best Paper Award)
paper / ICORES version

Rectilinear Steiner tree packing, the problem behind circuit routing, is hard even to find a feasible solution for. Our hierarchical optimizer decomposes it into high- and low-level sub-problems with far smaller search spaces, then composes their solutions.

Filling in the Gaps
Filling in the Gaps: LLM-Based Structured Data Generation from Semi-Structured Scientific Data
Hanbum Ko, Hongjun Yang, Sehui Han, Sungwoong Kim, Sungbin Lim, Kyunghoon Bae, Rodrigo S. Hormazabal
ICML Workshop on AI for Science, 2024
paper / talk

A framework for gathering, augmenting, and restructuring unstructured scientific documents with LLMs, applied to chemical reactions for document augmentation and knowledge-graph completion.

TSP with Drone
A Deep Reinforcement Learning Approach for Solving the Traveling Salesman Problem with Drone
Aigerim Bogyrbayeva, Taehyun Yoon, Hanbum Ko, Sungbin Lim, Hyokun Yun, Changhyun Kwon
Transportation Research Part C: Emerging Technologies, vol. 148, 2023
paper / journal / code

A hybrid attention-encoder / LSTM-decoder model for routing a truck and a drone in tandem, improving both solution quality and computation time over purely attention-based models.

ReSPack
ReSPack: A Large-Scale Rectilinear Steiner Tree Packing Data Generator and Benchmark
Kanghoon Lee, Youngjoon Park, Han-Seul Jeong, Sunghoon Hong, Deunsol Yoon, Sungryull Sohn, Minu Kim, Hanbum Ko, et al.
NeurIPS Workshop on SyntheticData4ML, 2022
paper

A generator and benchmark producing rectilinear Steiner tree packing instances at scale, with controllable size and difficulty, for training and comparing learned routing solvers.

  SwarmSense: Effective and Resilient Drone Swarm and Search for Disaster Response and Management Application
Cheolmin Jeon, Jeongsoo Ha, Hanbum Ko, Byeongman Lee, Bo Ryu
The World Congress on ANBRE, 2019

A drone-swarm sensing and search system for disaster response, resilient to the loss of individual drones.

  Augmenting Structure for Noise Reduction in UAV
Hanbum Ko, Yeeun Lee, Suyeon Jin, Emma Kang, Nick Noonan, Minsun Lee, Michael J. Hopmeier, Eric T. Matson
The World Congress on ANBRE, 2019

Structural augmentations to a UAV airframe that reduce the noise it radiates in flight.

Education

Sep 2023 – Present Ph.D. in Artificial Intelligence, Korea University
Advisors: Prof. Sungwoong Kim, Prof. Sungbin Lim
Mar 2021 – Aug 2023 M.S. in Artificial Intelligence, UNIST
Advisor: Prof. Sungbin Lim
Mar 2014 – Feb 2021 B.S. in Computer Science and Engineering, minor in Statistics, Chungnam National University
Study abroad at Purdue University, Dec 2018 – Jan 2019

Experience

Sep 2023 – Present Research & Teaching Assistant, AGI Laboratory, Korea University
Sep 2023 – Aug 2024 Research Intern, Materials Intelligence Lab., LG AI Research (Mentors: Rodrigo S. Hormazabal, Sehui Han)
Mar 2022 – Dec 2022 Research Intern, Advanced ML Lab., LG AI Research (Mentors: Sungryull Sohn, Moontae Lee)
Mar 2021 – Aug 2023 Research & Teaching Assistant, LIM Laboratory, UNIST
Mar 2019 – Feb 2021 Research Intern, EpiSys Science, Inc., Poway, CA, USA

Selected Projects & Awards

2023 – Present EXAONE Discovery Development · LG AI Research
2022 PCB Auto Routing · LG AI Research & LG Electronics
2021 NeurIPS 2021 Competition — Machine Learning for Combinatorial Optimization
2nd on the global leaderboard, 1st on the student leaderboard
2019 – 2020 AlphaDogFight Trials (hosted by DARPA) · EpiSys Science, Inc.
2020 Patent: System for Increasing Resolution of JPEG Compressed Image and Method Thereof
KR Reg. No. 10-2098375, assigned to CNU Industry-Academic Cooperation Foundation

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