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HY_NOTEBOOK

About

This is a personal blog about work, learning, and everyday life. Alongside software and operations notes, I want it to hold reflections on books, travel, and ordinary experiences.

I build Python and Node.js backends and work on keeping deployed services understandable and maintainable. My work has included sign-language accessibility, content production, and emergency notifications across cloud and on-premises environments.

How the work developed

From May 2018 to September 2024, I worked on APIs, Kubernetes delivery, CI/CD, monitoring, and incident response at an accessibility services company. Search synchronization, failed external calls, and incorrect notifications made investigation and operating records part of the development work.

Before that, I analyzed genomic data at a public health research institute from January 2014 to March 2017. Research and service development are different jobs, but preprocessing data and checking results remained useful when I later investigated audio and STT output.

Current public work

hy-home.docker holds my Compose home infrastructure, and hy-home.k8s covers local Kubernetes and GitOps. I keep learning notes and experiment conditions in hy-home.Learned. Current study includes data pipelines, AI tools, and web interfaces.

The career timeline records employment and responsibilities; projects cover implementation and outcomes. The skills pages distinguish professional use from personal study. My GitHub profile also records current public activity.

Education

  • M.S. in Life Science, Hanyang University (Seoul), March 2015–February 2017.
  • B.S. in Molecular Life Science, Hanyang University (ERICA), March 2007–February 2013.
  • Fast Campus Data Science School, August–December 2017.

Skills

Tools in context, distinguishing professional work, research, personal projects, and study.

Cloud and platform

  • Azure / NCP / NHN CloudProfessional · Configured service networking, integrations, test environments, and backend delivery.
  • Docker / Docker ComposeProfessional and personal · Built internal test environments; use include and explicit profiles for homelab service combinations.
  • Kubernetes / NKSProfessional · Worked with NKS microservices, HPA, disruption budgets, and pod placement.
  • NCP DevTools / GitHub ActionsProfessional and personal · Automated build/delivery flows and repository checks.
  • k3d / Helm / ArgoCDPersonal · Manage a local multi-node cluster and App-of-Apps/ApplicationSet declarations.
  • OpenBao / External SecretsPersonal · Work on the connection between an external secret store and Kubernetes.

Backend and databases

  • Python / Django / DRFProfessional · Built CRUD, search, upload, and state-management APIs for sign-language content.
  • Flask / FastAPIProfessional · Developed and maintained APIs connecting audio, STT, and sign-language matching services.
  • Node.js / Express.js / SequelizeProfessional · Implemented content APIs and data access, including refactoring Django APIs.
  • MySQL / MongoDBProfessional · Worked on persistence models and read/write logic for content, delivery, and service data.
  • Celery / RedisProfessional · Used for asynchronous platform jobs and caching.
  • OpenSearchProfessional · Implemented content search and synchronization between the database and search index.

Observability and incident response

  • Prometheus / GrafanaProfessional · Built metric collection and dashboards across Azure, NCP, and on-premises systems.
  • Node Exporter / Blackbox ExporterProfessional · Collected host metrics and externally observed service responses.
  • AlertmanagerProfessional · Connected monitoring events to notifications and response procedures.
  • Incident response / RunbooksProfessional · Defined SEV classification and detection, declaration, recovery, and improvement procedures.
  • OpenTelemetry / Loki / Tempo / AlloyPersonal and learning · Exploring log/trace collection and correlation.
  • SLI / SLO / Error budgetLearning · Studying user-journey success criteria, measurement windows, and error budgets.

Web interfaces and API integration

  • React / Next.js / ZustandLearning · Exploring components, routing, and client-state boundaries.
  • TypeScript / Tailwind CSSLearning · Working with interface/API types and responsive styling.
  • Swagger / OpenAPIProfessional · Documented request and response contracts for management and integration APIs.
  • AccessibilityLearning · Reviewing keyboard flow, accessible names, roles, states, and error messages.

AI tools and agent study

  • Ollama / Open WebUIPersonal · Manage local AI service definitions and prerequisites in the homelab.
  • LangChain / LangGraph / MCPLearning · Studying retrieval, tool calls, state flow, and connection permissions.
  • PyTorch / Hugging FaceLearning · Exploring model use, inference, and serving fundamentals.
  • Agent collaborationPersonal · Connect requirements, scope, and verification records, with provider-specific entry points.

Data analysis and pipelines

  • Pandas / Jupyter NotebookProfessional · Analyzed audio/STT output and delivery errors and prepared reports.
  • Python / cron / ETLProfessional · Automated recurring collection, preprocessing, and analysis to inform matching changes.
  • Samtools / LinuxResearch · Preprocessed genomic data and worked with variant frequencies and annotation.
  • NumPy / PolarsUse and learning · Comparing array and table processing and transformation approaches.
  • Kafka / Airflow / dbtLearning · Studying streaming, scheduling, transformation layers, and data quality checks.

Career

Backend/platform work at an accessibility services company and genomic analysis at a public health research institute.

  1. 2018.05–2024.09

    Engineer, Development Team — Backend / Platform / DevOpsAccessibility services company

    • Developed REST APIs and content-management backends using Django, Flask, FastAPI, and Express.js.
    • Configured cloud and on-premises services, Kubernetes deployments, CI/CD, and monitoring.
    • Analyzed audio/STT data, maintained sign-language services, and documented incident response.

  2. 2014.01–2017.03

    General Researcher, Division of Bio-Science InformationPublic health research institute

    • Preprocessed and analyzed DNA sequencing data using Samtools, Linux, and Python.
    • Examined genetic-variant frequencies and differences between populations.
    • Annotated variants using public databases as part of the KRGDB research.

Projects

Professional backend, delivery, analysis, and incident-response projects, plus current public repositories.

  1. General

    Barrier-free museum kiosk backend

    Developed content APIs and integrations for sign-language, audio, and Braille kiosks.

    Python · Django · Django REST Framework · Node.js · Express.js · MySQL · NHN Cloud · Prometheus · Alertmanager

  2. General

    Content production platform modernization

    Reworked content state, search, synchronization, and asynchronous processing.

    Python · Django · Django REST Framework · Celery · Redis · MySQL · MongoDB · OpenSearch · Azure

  3. General

    Emergency notifications for deaf users

    Processed CAP XML alerts and delivered notifications by user preferences and region.

    Python · Requests · Pandas · MySQL · MongoDB · Firebase Cloud Messaging · Azure · Nginx

  7. General

    Incident response process

    Defined incident severity, response roles, recovery steps, and follow-up.

    Incident Response · Runbooks · SEV

  8. General

    Initial sign-language content platform

    Built content CRUD, upload and state handling, and animation-module integration.

    Python · Django · Django REST Framework · MySQL · AWS · Azure · Nginx · Linux

  9. General

    KRGDB genomic database

    Contributed genomic preprocessing, variant analysis, and annotation for KRGDB.

    Linux · Python 2.x · Samtools · Vim

  10. General

    Multi-cloud and on-premises monitoring

    Connected metrics, dashboards, and alerts across cloud and on-premises environments.

    Prometheus · Grafana · Alertmanager · Node Exporter · Blackbox Exporter · Linux · Azure · NCP

  11. General

    Project Template · Repeated setup

    Organizes language and framework starters with code checks and CI configuration.

    Project Structure · Markdown · Static Analysis · CI Workflows

  12. General

    Sign-language matching and data analysis

    Compared audio, STT output, and delivery results to investigate matching errors.

    Python · Pandas · Jupyter Notebook · Requests · cron · NCP · Linux

  14. General

    Web-based avatar sign-language service

    Built APIs and the NCP Kubernetes delivery environment for a public-sector SaaS service.

    Python · Flask · Node.js · Express.js · MySQL · NCP · Kubernetes · Docker · Nginx