Seungju Han

Hi, I am Seungju Han, a first-year Ph.D. student in Computer Science at Stanford advised by Yejin Choi.

For research, I am:

improving language models to help solve challenging scientific problems; these days, interested in reasoning and knowledge of LLMs.
interested in data and training algorithms, and prefer very simple and clean ideas that are scalable.

Previously, I was:

research intern at NVIDIA (2024–2025): reasoning (Retro-Search, Prismatic Synthesis), pre-training data (Nemotron-H, Nemotron Nano 2)
visiting researcher at Allen Institute for AI (2022–2024): safety (WildGuard), VLM (Champagne)
ml engineer at Hyperconnect (acquired by Match Group for $1.7B; 2019–2022): social chatbots
studying in Korea: Seoul National University (2017–2024), Seoul Science High School (2014–2016)

Feel free to reach me if you are interested in chatting about research! + I will be at COLM 2025!

Research

Selected All

NVIDIA Nemotron Nano 2: An Accurate and Efficient Hybrid Mamba-Transformer Reasoning Model
NVIDIA

Tech report, 2025 Paper

Nemotron-H: A Family of Accurate and Efficient Hybrid Mamba-Transformer Models
NVIDIA

Tech report, 2025 Paper

Prismatic Synthesis: Gradient-based Data Diversification Boosts Generalization in LLM Reasoning
Jaehun Jung, Seungju Han*, Ximing Lu*, Skyler Hallinan*, David Acuna, Shrimai Prabhumoye, Mostafa Patwary, Mohammad Shoeybi, Bryan Catanzaro, Yejin Choi

NeurIPS 2025 (Spotlight, 3.1% acceptance rate) Paper / Blog

Nemotron-CrossThink: Scaling Self-Learning beyond Math Reasoning
Syeda Nahida Akter, Shrimai Prabhumoye, Matvei Novikov, Seungju Han, Ying Lin, Evelina Bakhturi, Eric Nyberg, Yejin Choi, Mostofa Patwary, Mohammad Shoeybi, Bryan Catanzaro

Preprint, 2025 Paper

Retro-Search: Exploring Untaken Paths for Deeper and Efficient Reasoning
Ximing Lu*, Seungju Han*, David Acuna*, Hyunwoo Kim*, Jaehun Jung*, Shrimai Prabhumoye, Niklas Muennighoff, Mostofa Patwary, Mohammad Shoeybi, Bryan Catanzaro, Yejin Choi

Preprint, 2025 Paper

Subtle Risks, Critical Failures: A Framework for Diagnosing Physical Safety of LLMs for Embodied Decision Making
Yejin Son*, Minseo Kim*, Sungwoong Kim, Seungju Han, Jian Kim, Dongju Jang, Youngjae Yu, Chanyoung Park

EMNLP 2025 Paper

Verifying the Verifiers: Unveiling Pitfalls and Potentials in Fact Verifiers
Wooseok Seo*, Seungju Han*, Jaehun Jung, Benjamin Newman, Seungwon Lim, Seungbeen Lee, Ximing Lu, Yejin Choi, Youngjae Yu

COLM 2025 Paper

G1yphD3c0de: Towards Safer Language Models on Visually Perturbed Texts
Yejin Choi, Yejin Yeo, Yejin Son, Seungju Han, Youngjae Yu

COLM 2025

Representation Bending for Large Language Model Safety
Ashkan Yousefpour*, Taeheon Kim*, Ryan S. Kwon, Seungbeen Lee, Wonje Jeung, Seungju Han, Alvin Wan, Harrison Ngan, Youngjae Yu, Jonghyun Choi

ACL 2025 Paper

MAPoRL: Multi-Agent Post-Co-Training for Collaborative Large Language Models with Reinforcement Learning
Chanwoo Park, Seungju Han, Xingzhi Guo, Asuman Ozdaglar, Kaiqing Zhang, Joo-Kyung Kim

ACL 2025 Paper

AI as Humanity's Salieri: Quantifying Linguistic Creativity of Language Models via Systematic Attribution of Machine Text against Web Text
Ximing Lu, Melanie Sclar, Skyler Hallinan, Niloofar Mireshghallah, Jiacheng Liu, Seungju Han, Allyson Ettinger, Liwei Jiang, Khyathi Chandu, Nouha Dziri, Yejin Choi

ICLR 2025 (Oral, 1.8% acceptance rate) Paper / Code

Do LLMs Have Distinct and Consistent Personality? TRAIT: Personality Testset designed for LLMs with Psychometrics
Seungbeen Lee*, Seungwon Lim*, Seungju Han, Giyoung Oh, Minju Kim, Beongwoo Kwak, Jiwan Chung, Hyungjoo Chae, Dongha Lee, Jinyoung Yeo, Youngjae Yu

NAACL Findings 2025 Paper

WildGuard: Open One-Stop Moderation Tools for Safety Risks, Jailbreaks, and Refusals of LLMs
Seungju Han*, Kavel Rao*, Allyson Ettinger, Liwei Jiang, Bill Yuchen Lin, Nathan Lambert, Yejin Choi, Nouha Dziri

NeurIPS 2024 Paper / Code / Data

WildTeaming at Scale: From In-the-Wild Jailbreaks to (Adversarially) Safer Language Models
Liwei Jiang, Kavel Rao*, Seungju Han*, Allyson Ettinger, Faeze Brahman, Sachin Kumar, Niloofar Mireshghallah, Ximing Lu, Maarten Sap, Yejin Choi, Nouha Dziri

NeurIPS 2024 Paper / Code / Data

Selective Vision is the Challenge for Visual Reasoning: A Benchmark for Visual Argument Understanding
Jiwan Chung, Sungje Lee, Minseo Kim, Seungju Han, Ashkan Yousefpour, Jack Hessel, Youngjae Yu

EMNLP 2024 Oral Paper

Multimodal Laughter Reasoning with Textual Audio-Visual Representation
Hyun Lee, Sung Bin Kim, Seungju Han, Youngjae Yu, Tae Hyun Oh

NAACL 2024 Paper

Reading Books is Great, But Not if You Are Driving! Visually Grounded Reasoning about Defeasible Commonsense Norms
Seungju Han, Junhyeok Kim, Jack Hessel, Liwei Jiang, Jiwan Chung, Yejin Son, Yejin Choi, Youngjae Yu

EMNLP 2023 Oral Paper

CHAMPAGNE: Learning Real-world Conversation from Large-Scale Web Videos
Seungju Han, Jack Hessel, Nouha Dziri, Yejin Choi, Youngjae Yu

ICCV 2023 Paper / Code

Measuring and Improving Semantic Diversity of Dialogue Generation
Seungju Han, Beomsu Kim, Buru Chang

EMNLP 2022 Paper

Meet Your Favorite Character: Open-domain Chatbot Mimicking Fictional Characters with only a Few Utterances
Seungju Han*, Beomsu Kim*, Jin Yong Yoo*, Seokjun seo, Sangbum Kim, Enkhbayar Erdenee, Buru Chang

NAACL 2022 Paper

Understanding and Improving the Exemplar-based Generation for Open-domain Conversation
Seungju Han*, Beomsu Kim*, Seokjun Seo*, Enkhbayar Erdenee*, Buru Chang

ACL 2022 4th Workshop on NLP4ConvAI Oral Presentation, Outstanding Paper Paper

Distilling the Knowledge of Large-scale Generative Models into Retrieval Models for Efficient Open-domain Conversation
Beomsu Kim*, Seokjun Seo*, Seungju Han*, Enkhbayar Erdenee*, Buru Chang

EMNLP 2021 Paper

Disentangling Label Distribution for Long-tailed Visual Recognition
Youngkyu Hong*, Seungju Han*, Kwanghee Choi*, Seokjun Seo, Beomsu Kim, Buru Chang

CVPR 2021 Paper / Code

Attentron: Few-Shot Text-to-Speech Utilizing Attention-Based Variable-Length Embedding
Seungwoo Choi*, Seungju Han*, Dongyoung Kim*, Sungjoo Ha

Interspeech 2020 Paper