Backend Engineer — I design distributed services on Java/Spring and own them all the way through deployment and operations.
- 🔧 I build systems end-to-end — from Kafka event pipelines and MSA to K3s + GitOps deployment
- ⚡ I enjoy the tricky parts: concurrency, race conditions, and real-time processing
- 🤖 I work with AI as a pair across the whole development lifecycle
C4I System — Target Tracking · API Gateway · Threat Intel AI
Real-time object tracking + AI threat analysis, polyglot MSA on a self-built K3s cluster
Java 21 Spring Boot Kafka Python FastAPI K3s ArgoCD WebSocket
- Streams a drone simulator and a live ADS-B feed (adsb.fi) to a real-time dashboard through a Kafka → WebSocket pipeline
- Two AI services with different approaches (pgvector + Gemini RAG / LangGraph + Qdrant) consume the same topic as independent consumer groups
- Verified zero-touch deployment end to end: GitHub Actions → Docker Hub → ArgoCD Image Updater write-back
- Migrated from VMware to Multipass to fix recurring node OOM / NotReady failures
AI-powered group travel planner — Gradle multi-module MSA backend
Java 21 Spring Boot 3 Spring AI Kafka PostgreSQL Redis Grafana
- Monorepo with two independently deployed services: layered (
travel-core) and hexagonal (travel-supply) - Three-step trip recommendations with Gemini 2.5 Flash (Spring AI) and Redis-backed conversation memory; saving a flight updates the user's travel map via Kafka
- Observability with Prometheus · Grafana · Zipkin; zero-downtime Nginx blue-green deployment
Real-time co-op café tycoon — solving race conditions in multiplayer state
Java 17 Spring Boot 3 WebSocket(STOMP) Redis
- Eliminated the race condition where two players grab the same order at once, using an atomic Redis Lua script
- Producer-consumer order queue on Redis Lists, SETNX to prevent double-assigning tables, Pub/Sub to broadcast state changes
📁 More Projects
| Project | Description | Key |
|---|---|---|
| Connecteamed | Team collaboration platform covering a project from kickoff to retrospective (UMC 9th) | QueryDSL · JWT/OAuth2 · AWS Lightsail |
| SikjajaeDeal | Location-based B2B marketplace and search platform for food ingredients | Elasticsearch · KakaoMap API |
| LikeLion-RealTalk | Real-time debate platform with Claude AI fact-checking | WebSocket Pub/Sub · Redis |
| memory-viz | Real-time visualizer for macOS physical and virtual memory layout | Python · vm_stat · vmmap |
Backend
Infra
Tools
Dev Environment — Ghostty · Zsh · tmux · Neovim(LazyVim) · Hammerspoon, all version-controlled in my dotfiles
⏱ WakaTime Metrics (auto-updated daily)
💡 Other is terminal time tracked by WakaTime (tmux, zsh, etc.)
🐱 My GitHub Data
📦 275.8 kB Used in GitHub's Storage
🏆 1,873 Contributions in the Year 2026
🚫 Not Opted to Hire
📜 35 Public Repositories
🔑 3 Private Repositories
I'm a Night 🦉
🌞 Morning 1225 commits ██░░░░░░░░░░░░░░░░░░░░░░░ 08.14 %
🌆 Daytime 5631 commits █████████░░░░░░░░░░░░░░░░ 37.40 %
🌃 Evening 4688 commits ████████░░░░░░░░░░░░░░░░░ 31.14 %
🌙 Night 3513 commits ██████░░░░░░░░░░░░░░░░░░░ 23.33 %
📅 I'm Most Productive on Friday
Monday 1920 commits ███░░░░░░░░░░░░░░░░░░░░░░ 12.75 %
Tuesday 2310 commits ████░░░░░░░░░░░░░░░░░░░░░ 15.34 %
Wednesday 2495 commits ████░░░░░░░░░░░░░░░░░░░░░ 16.57 %
Thursday 2004 commits ███░░░░░░░░░░░░░░░░░░░░░░ 13.31 %
Friday 3155 commits █████░░░░░░░░░░░░░░░░░░░░ 20.95 %
Saturday 1995 commits ███░░░░░░░░░░░░░░░░░░░░░░ 13.25 %
Sunday 1178 commits ██░░░░░░░░░░░░░░░░░░░░░░░ 07.82 %
📊 This Week I Spent My Time On
💬 Programming Languages:
Other 16 hrs 47 mins ███████████████░░░░░░░░░░ 60.38 %
Markdown 7 hrs 20 mins ███████░░░░░░░░░░░░░░░░░░ 26.39 %
Python 1 hr 27 mins █░░░░░░░░░░░░░░░░░░░░░░░░ 05.24 %
Bash 1 hr 1 min █░░░░░░░░░░░░░░░░░░░░░░░░ 03.71 %
Swift 25 mins ░░░░░░░░░░░░░░░░░░░░░░░░░ 01.51 %
🔥 Editors:
Ghostty 15 hrs 34 mins ██████████████░░░░░░░░░░░ 55.96 %
Claude Code 11 hrs 12 mins ██████████░░░░░░░░░░░░░░░ 40.28 %
Neovim 57 mins █░░░░░░░░░░░░░░░░░░░░░░░░ 03.47 %
iTerm2 4 mins ░░░░░░░░░░░░░░░░░░░░░░░░░ 00.27 %
Terminal 0 secs ░░░░░░░░░░░░░░░░░░░░░░░░░ 00.02 %
🐱💻 Projects:
portfolio 8 hrs 34 mins ████████░░░░░░░░░░░░░░░░░ 30.83 %
ghostty 4 hrs 42 mins ████░░░░░░░░░░░░░░░░░░░░░ 16.92 %
sm010422 4 hrs 9 mins ████░░░░░░░░░░░░░░░░░░░░░ 14.92 %
terminal_backup 3 hrs 42 mins ███░░░░░░░░░░░░░░░░░░░░░░ 13.30 %
personal-knowledge-graph-1 hr 55 mins ██░░░░░░░░░░░░░░░░░░░░░░░ 06.92 %
💻 Operating System:
Mac 27 hrs 49 mins █████████████████████████ 100.00 %
🤖 AI Coding This Week
⏱ AI Coding Time: 17 hrs 3 mins (61.33%)
✍️ 5,020 lines written by AI, 234 lines written by hand (95.55% AI-written)
🔤 5,347,016 Input Tokens, 1,314,879 Output Tokens
💵 $92.19 Estimated AI Cost This Week
🧠 33 AI Sessions, 331 AI Prompts
Opus 5,130 lines █████████████████████████ 100.00 %
🔎 AI Coding Insights:
🤖 AI-Driven — 95.55% of written lines came from AI
📄 Detailed Prompter — average 562 characters per prompt
🔁 Iterative Prompter — average 10 prompts per session
🚀 High AI Trust — 4.65% of changed lines were hand-edited
I Mostly Code in Java
TypeScript 6 repos ████░░░░░░░░░░░░░░░░░░░░░ 15.00 %
Python 3 repos ██░░░░░░░░░░░░░░░░░░░░░░░ 07.50 %
Go 2 repos █░░░░░░░░░░░░░░░░░░░░░░░░ 05.00 %
Ruby 1 repo █░░░░░░░░░░░░░░░░░░░░░░░░ 02.50 %
Dockerfile 1 repo █░░░░░░░░░░░░░░░░░░░░░░░░ 02.50 %
Last Updated on 08/11/2026 22:26:39 UTC