README.md

"What remains is not the code, but the structure behind it."

Hi, I'm a Python Backend Engineer who cares deeply about maintainability, clarity, and developer experience.
I believe that a well-designed system architecture outlasts implementation details — and that's what I aim for every time I write code.

📘 Recent

Project

• (SIDE-PROJECT)POOMASI - BackEnd
  • Domain-Centric Architecture with DDD
    • Designed and developed the backend using FastAPI with Domain-Driven Design and a layered architecture.
    • Clearly separated Domain, Use Case, Interface, and Infrastructure layers to keep business logic independent and resilient to change.
  • Pure Domain Model & Testable Design
    • Implemented pure domain models by separating business logic from persistence using SQLAlchemy Imperative Mapping.
    • Adopted dependency injection with python-dependency-injector to reduce coupling and significantly improve testability and maintainability.
  • Use Case–Driven Business Logic & External Integration
    • Encapsulated complex business logic into a dedicated Use Case layer covering account management, Q&A, company/job postings, and skill/domain management.
    • Integrated external services (AWS S3, Kakao OAuth/OIDC, FCM, Slack, Toss) via the Adapter pattern and improved scalability through middleware-based authentication, security, and event handling.

Writing

Check out my blog for dev logs, experiments, and learnings.

• 환경변수 관리 도구인 Infisical 에 대한 노트 (2026-01-22)
• Docker를 이용한 Swap 메모리 증설과 OOM 테스트 (2025-12-30)
• TryHackMe : Cheese (2025-12-08)
• TryHackMe : gallery (2025-12-05)
• TryHackMe : Dreaming (2025-12-05)

🔍 Characteristic

• 🧱 Builds for the long term
  • From small APIs to large-scale services, I think about how today's choices affect tomorrow's developers.
• 🛠️ Loves clean abstractions:
  • I enjoy crafting code that speaks for itself and designing systems that scale with clarity.
• ✍️ Writes to learn
  • Whether it’s documenting a tricky test setup or reflecting on tools like PyCrunch, I treat writing as part of the craft.
• 🔄 Iterates constantly
  • I experiment, test, reflect — and repeat. Tools are replaceable, but reasoning skills aren't.

🧩 Philosophy

I treat code not as a product, but as a process.
In a world of ever-changing requirements, structure is what survives.

Experience of Impact

🔐 Security & Reliability

Experience in enhancing service security and ensuring system reliability through vulnerability assessment and mitigation.

• Identified and mitigated a SQL Injection vulnerability in a Serverless environment
  Reproduced a UNION-based SQLi attack using the SLEEP() function on unsafe string-formatted queries,
  and proposed secure parameterized query methods to fix the issue.
• Assessed and addressed a Server-Side Template Injection (SSTI) vulnerability
  Experimentally reproduced exploitation scenarios causing server lockups in PDF generation,
  then designed and applied input validation limits to protect system stability.
• Performed security audits for public sector servers
  Conducted web and server vulnerability assessments following KISA guidelines for institutions such as Korea Land and Geospatial Informatix Corporation and Korea Transportation Safety Authority.

⚙️ Performance Optimization & Infrastructure

Experience optimizing legacy systems and improving infrastructure to boost performance and scalability.

• Improved data collection performance by approximately 30% by migrating from Selenium to API-based integration
  Analyzed Keycloak-based authentication systems and implemented API token exchange via password grant,
  significantly reducing scraping latency.
• Optimized currency rate scraping by 85–90%
  Replaced Selenium-driven scraping with direct HTTP requests using session cookies,
  reducing runtime from 15–20 seconds down to 2–3 seconds.
• Achieved zero data loss in a real-time GPU monitoring system
  Diagnosed ~20% data packet loss across 250 GPUs and introduced L7 load balancing to ensure reliable data ingestion.

🧱 System Design & Automation

Experience designing reusable system components and implementing automation to enhance quality and developer productivity.

• Designed and developed a unified data collection module for five major advertising platforms
  Reduced platform-specific variations by creating reusable structures, contributing over 80% of the design and implementation.
• Established automated testing infrastructure achieving 71% test coverage
  Introduced pytest-based automated tests for a previously manually verified system, improving stability and maintainability.
• Developed Python-based crawlers for dynamic content aggregation
  Built and deployed YouTube and Instagram crawlers using Selenium with dynamic rendering handling, successfully applied in healthcare content projects.

Contact

• Email : [email protected]