1. Project Mandu (May 2024 - Ongoing)- Driving development roadmap for new service- Leading backend implementation using Java and Spring frameworks

1. Access Control Library Development (Feb 2023 - Mar 2023)- Designed and developed APIs to restrict access to authorized admin users only, strengthening admin function security- Optimized MongoDB with projection, aggregation, and indexing, achieving 26% improvement in average response time2. User MSA Service Refactoring and Migration (Oct 2021 - Oct 2022)- Refactored existing MSA service logic to decouple layers and increase development productivity- Wrote unit tests, increasing test coverage from 0% to 55%- Categorized, documented APIs aligning with MSA architecture and implemented new ones, achieving 70% MSA transition rate- Documented code conventions and review rules, fostering an improved code review culture3. Class Enrollment Page Optimization (Jul 2021 - Sep 2021)- Analyzed logs and query execution plans to identify slow queries- Optimized MongoDB queries using projection and aggregation, improving average response time by 50%- Refactored class enrollment logic4. Inactive User Management (Apr 2023 - Jun 2023)- Automated large-scale user data processing using Spring Batch for efficiency and accuracy- Transitioned users inactive for 1 year to dormant status and segregated personal information- Migrated data of approximately 2.4 million existing long-term inactive users- Managed inactive user process to comply with data privacy laws, prevent penalties, and identify active users for marketing efficiency