Writing on systems, Rust, and open source.https://scanf-s.github.io/https://scanf-s.github.io/blog/boeing-internship-review/https://scanf-s.github.io/blog/boeing-internship-review/A firsthand account of interning as a Student Software Engineer on the Cloud Systems team at Boeing Korea Engineering & Technology Center, covering recruitment, daily life, and key professional takeaways.Thu, 12 Mar 2026 00:00:00 GMThttps://scanf-s.github.io/blog/github-actions-self-hosted-runner/https://scanf-s.github.io/blog/github-actions-self-hosted-runner/How migrating from GitHub-hosted runners to native ARM64 AWS EC2 self-hosted runners eliminated QEMU emulation overhead and cut average build time from 15 minutes to 4 minutes.Mon, 27 Apr 2026 00:00:00 GMThttps://scanf-s.github.io/blog/optimizing-cicd-pipeline/https://scanf-s.github.io/blog/optimizing-cicd-pipeline/How the homepage-backend CI/CD pipeline was redesigned with GitHub Actions, standardized AWS ECR/ECS/SSM integration, SHA-based image tagging, and verifiable health checks to reduce deployment failures and recovery time.Sun, 01 Feb 2026 00:00:00 GMThttps://scanf-s.github.io/blog/retrieval-augmented-generation-system/https://scanf-s.github.io/blog/retrieval-augmented-generation-system/A detailed log of 33 experiments building a production RAG system for Korean legal multiple-choice questions, documenting iterative pipeline improvements that lifted accuracy from a 51.58% baseline to 53.67%.Mon, 30 Mar 2026 00:00:00 GMThttps://scanf-s.github.io/blog/fix-and-refactor-enums/https://scanf-s.github.io/blog/fix-and-refactor-enums/How a simple request to add AI school accounts grew into a full ENUM refactor: renaming departments, exposing a Category API endpoint, migrating the database column from enum to VARCHAR, and fixing a filtering hierarchy bug.Sun, 08 Mar 2026 00:00:00 GMThttps://scanf-s.github.io/blog/single-sign-on/https://scanf-s.github.io/blog/single-sign-on/How a student IT team replaced per-project login code with AWS Cognito-backed SSO, syncing user data between Cognito and RDS via Lambda triggers and VPC Peering.Fri, 05 Dec 2025 00:00:00 GMThttps://scanf-s.github.io/blog/observability-improvement-plan/https://scanf-s.github.io/blog/observability-improvement-plan/A plan to standardize logging across university IT services using OpenTelemetry and Elastic Common Schema, enabling distributed tracing, structured JSON logs, and a centralized Prometheus + Grafana Loki monitoring stack.Sat, 14 Mar 2026 00:00:00 GMThttps://scanf-s.github.io/blog/replacing-tokenbucket-in-cadence-cli/https://scanf-s.github.io/blog/replacing-tokenbucket-in-cadence-cli/An open-source contribution to the Cadence distributed orchestration engine that swapped a redundant custom token-bucket implementation for Go's standard rate limiter, while adding input validation to prevent infinite-wait deadlocks.Sat, 17 Jan 2026 00:00:00 GMThttps://scanf-s.github.io/blog/ez-http-constants-using-directive-fix/https://scanf-s.github.io/blog/ez-http-constants-using-directive-fix/An open-source contribution to the EZ language that added named HTTP status code constants and fixed the type checker so the 'using' directive correctly brings stdlib constants into scope.Fri, 02 Jan 2026 00:00:00 GMThttps://scanf-s.github.io/blog/ssunnounce-scraper/https://scanf-s.github.io/blog/ssunnounce-scraper/A major refactor of the SSU Announcement Scraper replaced headless-Chrome scraping with a direct API, cutting execution time from 44 to 3 seconds and code from 735 to 208 lines while adding unit and integration tests.Fri, 05 Dec 2025 00:00:00 GMThttps://scanf-s.github.io/blog/itsupport-aws-blueprint/https://scanf-s.github.io/blog/itsupport-aws-blueprint/A blueprint for redesigning a student club's AWS infrastructure to fix availability, scalability, and cost issues while staying under $150/month using Fargate, Spot instances, and containerized databases.Wed, 21 Jan 2026 00:00:00 GMThttps://scanf-s.github.io/blog/how-to-audit/https://scanf-s.github.io/blog/how-to-audit/A practical guide to adding insider-access traceability for a student organization's AWS infrastructure using SSM session logging to S3, Lambda-based PII scrubbing, and Discord alerts via EventBridge.Wed, 18 Feb 2026 00:00:00 GMT