About me

I am an incoming PhD student at the University of Illinois Urbana-Champaign (UIUC) School of Information Sciences, starting Fall 2026, where I am fortunate to be advised by Prof. Yonghan Jung.

Previously, I was an AI Engineer at NAVER, where I worked on off-policy evaluation for large-scale online ad auction systems and designed an LLM-as-a-Judge evaluation framework for automated quality assessment of AI-generated search responses, including bias mitigation strategies and an ensemble judging pipeline to replace human annotation at scale. I received my M.S. and B.S. in Electrical Engineering from KAIST, advised by Prof. Changho Suh.

Research Interests

• Causal Inference — counterfactual reasoning, off-policy evaluation
• Agentic AI — llm-as-a-judge, evaluation bias mitigation
• Recommender Systems — data bias and scarcity, cold-start problems

News

• [Aug. 2026] Begin Ph.D. at UIUC, School of Information Sciences.
• [Nov. 2025] Paper accepted at IEEE ICDM 2025 — Best Paper Award Finalist.
• [Aug. 2025] Joined NAVER as an AI Engineer.

Selected Publications

On Predicting Post-Click Conversion Rate via Counterfactual Inference
Junhyung Ahn and Sanghack Lee
IEEE International Conference on Data Mining (ICDM), 2025

Matrix Completion with Hierarchical Graph Side Information
Adel Elmahdy*, Junhyung Ahn*, Changho Suh, and Soheil Mohajer (*Equal contribution)
Conference on Neural Information Processing Systems (NeurIPS), 2020