Lunit, Seoul
Mar 2025 - Present
AI Research Scientist
- Deceptive Grounding: conceived and led a first-author study of entity-attribution failure in clinical RAG, from the research question and controlled benchmark to analysis, deployment evaluation, and writing. Accepted to the NeurIPS 2026 main track.
- Medical-model post-training: owned post-training and evaluation for Chain of Evidence, contributing to the public L1-16B-A3B and L1-30B-A5B models. Built synthetic-data and tool-use SFT pipelines; implemented and comparatively evaluated on-policy self-distillation, leading its adoption in the production training pipeline.
- Model-side safety: lead this work within Lunit's contribution to AI4ALL (ModuAI), a Kakao-led national consumer-AI initiative. Authored a priority-ordered behavior specification for a medical-information agent and designed tests of unsafe responses, unnecessary refusals, and faulty tool outputs.
- Training and behavior analysis: conducted GRPO, SDPO, and reward-modeling experiments. Diagnosed reward hacking and checkpoint regressions through model outputs, reasoning traces, and evaluation signals, revising data, objectives, templates, or serving configurations accordingly.
- External evaluation: led acceptance-evaluation delivery, from task data and post-training to a checkpoint with a reproducible evaluation harness. Designed rubric-based agent benchmarks and blinded clinician evaluation with hospital partners.
- Pathology models: develop self-supervised Vision Transformers for whole-slide pathology, studying positional encoding, optimization, and transfer. Built fault-tolerant distributed inference for clinical-scale image collections.
- Evaluation lead, Conquer Health: designed HealthBench-based scoring against frontier baselines and a blinded clinician evaluation protocol for the August 2026 hackathon.
- Research culture: lead Lunit's recurring AI paper-study program and write for its official technical publication, including You Could Have Invented Dr.GRPO Yourself.
Deceptive Grounding: studied entity-attribution failure across 13 models and a 740-pair sample from one clinical RAG deployment. Project · Paper · Code