Dohyun worked on the gsainfoteam/groups-be repository, focusing on backend development and database management using TypeScript, NestJS, and Prisma. Over the course of a month, Dohyun unified group membership logic by consolidating two separate user removal methods into a single, streamlined function within the GroupRepository, updating the GroupService to consume this new API. This change improved code maintainability and consistency. Additionally, Dohyun addressed a bug where deleted groups were still visible to third parties by refining database queries to exclude such records. The work demonstrated a methodical approach to code cleanup and targeted improvements in group visibility and user management.