Gihun Cho

AI Research Engineer, Motif Technologies

I work on post-training and evaluation for large language models.

Experience

2026 —

AI Research Engineer, Motif Technologies

Reinforcement learning for agentic tasks, evaluation and benchmark design, and supervised fine-tuning data pipelines.

2023 – 2026

Graduate Researcher, Innovative Radiology AI Lab (iRAIL)

Seoul National University. Advised by Chang Min Park, M.D., Ph.D. Clinical evaluation of medical LLMs and VLMs; metrics and benchmarks for radiology report generation.

Publications

CREPE: Rapid Chest X-ray Report Evaluation by Predicting Multi-category Error Counts

Gihun Cho, Seunghyun Jang, Hanbin Ko, Inhyeok Baek, Chang Min Park

Proceedings of EMNLP 2025, Main Conference (poster). Suzhou, China.

Six radiology-specific error categories, each regressed by its own head on a BiomedBERT encoder and summed into one score. Trained on 32k synthetic report pairs; agrees with radiologists on ReXVal at τ = 0.786 while running in 9.5 ms per pair — roughly 280× faster than an LLM judge.

ACL Anthology OpenReview Project page Code

Exploring the Capabilities of Large Language Model Encoders for Image-Text Retrieval in Chest X-rays

Hanbin Ko, Rong Yang, Gihun Cho, Inhyeok Baek, Donguk Kim, Joonbeom Koo, Changi Kim, Dongheon Lee, Chang Min Park

IEEE Journal of Biomedical and Health Informatics (2026).

A bidirectional LLM text encoder adapted to chest radiograph reports, trained with masked token prediction and supervised contrastive learning over stylistically different but clinically equivalent variants of the same report, then dropped into a dual-tower vision-language framework.

DOI arXiv

SeamXSim: Seamless-textured virtual colonoscopy simulator via unpaired long-term video translation

Seunghyun Jang, Dongheon Lee, Yisak Kim, Gihun Cho, Kwang Woo Kim, Sihyun Kim, Jong Pil Im, Byeong Gwan Kim, Chang Min Park

Computers in Biology and Medicine 198, 111217 (2025).

Seamless colon textures synthesized from a single exemplar by inpainting and outpainting, then carried through an unpaired video translation stage to produce long-term colonoscopic sequences from simulation.

DOI PubMed

Evaluating Open and Closed-Source Language and Vision-Language Models for Multicenter Image-Based Diagnosis in Radiology

RSNA 2024, Cutting-Edge Research (abstract). Chicago, USA. First author, equal contribution.

How far open-weight models had closed the gap with commercial ones on differential diagnosis, given images, patient history and findings text together, measured against reader performance across multiple centers.

Software

2025

crepe

Reference implementation and released weights for the EMNLP 2025 paper. Scores a chest X-ray report against its reference in one call.

2025

rrg-metric

Nine metrics for radiology report generation behind a single interface, so that a full evaluation fits in under ten lines.

Education

2024 – 2026

M.S. Bioengineering, Seoul National University

2018 – 2024

B.S. Biomedical Engineering, Hanyang University

2015 – 2018

Software Development, Sunrin Internet High School