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HY_NOTEBOOK

About Me

Backend, Platform & DevOps Engineer

I've spent most of my career building backend systems and platform infrastructure with Python and Node.js. My work has ranged from public-sector B2G/B2B SaaS platforms to real-time high-availability notification systems and multi-cloud SRE monitoring — all across Azure, Naver Cloud Platform (NCP), and on-premise hybrid environments. I designed and operated these systems myself and learned what it takes to keep them running.

Early on, shipping features was the whole job. Over time, though, the question shifted: "How fast does this system come back when something breaks?" That question stuck with me. Since then, I've focused on HA architecture, observability, and practical incident response workflows.

I've built CI/CD pipelines on NCP DevTools (Source Commit/Build/Deploy) and GitHub Actions, operated real-time anomaly detection with Prometheus, Grafana, and Alertmanager, and put together search (OpenSearch), caching (Redis), async processing (Celery), and ETL pipelines. The common thread has been balancing availability and performance.

When we migrated a public SaaS product to NCP-based microservices, I handled the CSAP, K-PaaS, and national security certifications directly. That meant addressing security requirements at the architecture level, not just checking boxes. On the performance side, I improved our notification pipeline to cut the error rate by 75% while scaling the system to handle 5x the load. Standardizing our monitoring brought MTTR down by 30%.

More recently, I've been expanding from my backend and infrastructure roots into data engineering pipelines, AI/LLMOps, and Infrastructure as Code.

What I'm focused on right now

I'm deepening the skills I already use in production while methodically learning new areas.

DevOps & GitOps

Topic Goal
ArgoCD + Helm GitOps workflows Implement canary and blue-green deployments hands-on
Terraform for NCP/Azure infrastructure Establish multi-cloud IaC patterns
GitHub Actions / NCP DevTools improvements Fully automate the test-build-deploy cycle
Kubernetes Operator patterns Operate custom resources via CRDs

Data engineering

Topic Goal
Apache Kafka + Schema Registry Build event-driven architectures from scratch
Apache Airflow ETL pipelines Design DAG-based scheduling and data workflows
Polars/Pandas data transformation High-performance data processing and analysis automation
dbt (Data Build Tool) Codify and test the transformation layer

Backend (going deeper)

Topic Goal
Go & Java/Spring Boot Expand backend capabilities beyond Python/Node
gRPC + Protocol Buffers Experiment with high-performance service-to-service communication
Async processing (Celery, Redis Queue) Push-test performance limits and optimize
Clean Architecture / DDD Apply domain-driven design in practice

Infrastructure & databases

Topic Goal
PostgreSQL HA (Patroni/pg_auto_failover) Battle-test failover in real operating conditions
Redis Cluster mode Develop recovery strategies for different failure scenarios
MinIO + Harbor Self-host private registries and object storage
InfluxDB / time-series databases Optimize time-series data management and queries

Observability

Topic Goal
OpenTelemetry-based distributed tracing Adopt distributed tracing as a standard
Loki + Tempo + Alloy stack Build a unified log/trace analysis pipeline
SLO/SLI definition & error budgets Quantify incident response effectiveness
eBPF-based observation Gain kernel-level performance visibility

Frontend (expanding toward full-stack)

Topic Goal
Next.js App Router + TypeScript Build production-quality UIs
React Query + Zustand Learn server state management patterns
API contract design Design backend APIs with UX in mind

AI / ML & LLMOps

Topic Goal
Ollama + LangChain + LangGraph Build local AI agents
MCP (Model Context Protocol) Tool integration and agent orchestration
PyTorch / Hugging Face Fine-tuning experiments and model serving basics
MLflow / Weights & Biases Experiment tracking and model management (MLOps)

Skills

Tools used across infrastructure, backend, observability, modern web, and AI.

Infra & Platform

  • Terraform (NCP/Azure)
  • Docker
  • ArgoCD (GitOps)
  • Istio

Backend & Database

  • Python (Celery)
  • Redis Cluster
  • PostgreSQL HA
  • Kafka (EDA)

Observability

  • Prometheus
  • Grafana
  • Loki
  • Tempo
  • Alloy

AI

  • LangChain

Modern Web

  • Next.js
  • React
  • TypeScript

Experiences

Experience across platform engineering, reliability, and AI development.

  1. Current

    Full-stack AI ResearcherInnovation & Future Tech

    • Building intelligent agents with Ollama and LangChain to automate internal workflows.
    • Expanding into full-stack development with Next.js, React, and TypeScript.
    • Researching Kafka-based Event-Driven Architectures (EDA) for data flow control.

  2. Continuous

    Backend ArchitectSystems Engineering & Reliability

    • Optimized API performance and implemented large-scale async processing with Redis/Celery.
    • Reduced MTTR by 30% by integrating Loki, Tempo, and Alloy for observability.
    • Implemented self-healing recovery systems with PostgreSQL HA and Redis Cluster.

  3. 6+ Years

    Platform & DevOps LeadInfrastructure Transformation

    • Automated 100% of NCP/Azure infrastructure provisioning with Terraform.
    • Built GitOps environments using ArgoCD and Istio for declarative operations.
    • Engineered Docker-based home server infrastructure integrating PostgreSQL HA and Kafka.

  4. 2018.05~2024.09 (6 Years 4 Months)

    Backend & DevOps EngineerEQ4ALL

    • Built fully automated CI/CD pipelines using NCP DevTools and GitHub Actions.
    • Integrated Prometheus, Grafana, and Alertmanager for real-time observability, reducing MTTR by 30%.
    • Designed Patroni-based PostgreSQL HA and Redis Cluster failover architectures to ensure 24/7 uptime.

  5. 2018.05~2024.09 (6 Years 4 Months)

    BioInformatics General ResearcherKNIH (Korea National Institute of Health)

    • Automated preprocessing and analytical workflow execution for large-scale genomic datasets.
    • Maintained secure biomedical database and computing environments for national researchers.
    • Optimized high-performance computing (HPC) and cloud data infrastructure for genomic analysis.

Projects

Selected technical projects with implementation notes.

  1. General

    hy-home.docker (Home Server Infrastructure)

    This repository packages the open-source services used on my home server as Docker containers. It gives beginners and experienced users a straightforward way to build a personal cloud, with volume mounts for data persistence, isolated networks for service communication, and environment variables for security settings.

    Linux · Docker · Docker Compose · GitHub Actions · Shell Scripts · Bridge Network · Reverse Proxy

  2. General

    hy-home.k8s (Kubernetes Homelab Architecture)

    This repository contains declarative Kubernetes configurations for the microservices used on my home server. Namespaces separate services, Persistent Volumes (PV) manage data, and Ingress handles external access, bringing cloud-native operations to a home lab.

    Kubernetes · ArgoCD · Helm · Ingress Controller (Nginx/Traefik) · MetalLB · Prometheus · Grafana

  3. General

    Project Template (Modular Blueprint)

    A reusable Blueprint for starting projects quickly. Its standard directory structure, Code Conventions, and automated workflows reduce initial infrastructure setup, leaving more time for core Business Logic.

    Modular Architecture · ESLint · Prettier · GitHub Actions