Hyeonjun Kil
Backend Engineer
About
Backend engineer with 3 years and 7 months of experience across 4 domains (Education, Healthcare, Clinical Trials, Gaming), achieving quantifiable results including 82% BigQuery cost reduction, complete resolution of clinical trial system Deadlocks, and contributing to major hospital contract acquisitions. Specialized in system design from monolithic to Event-Driven cloud-native architectures, creating long-term business value through root cause analysis and systematic solutions.
Experience
DEV Team Server Developer
GameDuo
2025-01 — Present
Mobile game development and publishing company
- 82% BigQuery Cost Reduction: Storage Read API adoption ($6.25→$1.1 per TB)
- Serverless Architecture: Event-Driven Architecture based AWS Lambda migration
- Marketing Integration Platform: Google Ads/Meta/TikTok unified dashboard
- Game Data Audit System: Repository abstraction-based balance change tracking
Dev2 Team Docs Squad Backend Engineer
JNPMedi
2023-06 — 2024-08
Clinical trial data management solution startup with 16B KRW cumulative investment
- Complete Deadlock Resolution: Foreign key lock timing analysis preventing clinical trial notification failures
- New Contract Contribution: User-organization 1:N structure enabling major hospital and pharma company contracts
- Rapid MVP Launch: VDR 3 weeks, TMF 3 months emergency deployment meeting deadlines
- Event-Driven Architecture: AWS SNS/SQS based system reliability improvement
Dev Team Backend Engineer
Medgo
2022-04 — 2023-06
Telemedicine and medication delivery platform startup with 300K cumulative downloads
- Architecture Modernization: Express.js → NestJS transition for code consistency and type safety
- Unified Authentication System: JWT-based subdomain session conflict resolution
- Medical Service Automation: OCR + public API for automated prescription medication guidance
- Real-time Optimization: Socket.IO Room targeting for network traffic optimization
Dev Team Backend Engineer
SimpleHAN
2021-07 — 2022-04
Custom software solutions SI company
- Bulk Data Processing: Apache POI-based batch processing for hundreds of member records
- Multi-country Unified Auth: JWT-based cross-domain login system
- Deployment Automation: Travis CI-based CI/CD eliminating hosting costs
- Legacy Integration: iframe-based PHP system non-disruptive feature extension
Technical Skills
Education
Inha Technical College
Bachelor's • Computer Information Engineering
2022-02 — 2023-02 GPA: 4.10/4.5
Inha Technical College
Associate • Computer Information
2017-02 — 2022-02 GPA: 4.16/4.5
Certifications
Engineer Information Processing
Human Resources Development Service of Korea • 2023-06