Byun Hyunseok

  • Frontend Engineer / AI Engineer•
  • Seoul, South Korea•
  • 95. 07. 01
  • • Frontend architecture design
  • • Design system development and documentation
  • • Reduced load time from 350ms -> 90ms through data caching optimization
  • • Reduced feature delivery time from 5 days -> 1.5 days through AI automation
  • • Reduced debugging time from 1 day -> half a day
  • • Service stabilization for 1,000 concurrent users

Work Experience

Global Knowledge Korea

Seoul, South Korea

Frontend Engineer / AI Engineer

24. 03. 18 - 26. 09. 30

  • Flunti
    Next.jsReactTailwindTanStack QueryECS
    • Led frontend architecture and delivery for a SaaS platform serving 15+ enterprise sites
    • Integrated TanStack Query and Next.js Fetch API caching to improve DX and reduce page load time from 350ms -> 90ms
    • Optimized proxy-layer data caching, reducing total reference-data load time from 100ms -> 65ms
    • Built reusable Metadata and JSON-LD helpers for SEO
  • Design System
    NextjsRadixUITailwindStoryBook
    • Designed and implemented a React-based component library, collaborating with a designer to build 20+ reusable components
    • Adopted Storybook and developed a feedback plugin
    • Built and deployed a design system documentation site with Next.js and Storybook
    • Ensured UI consistency across sites and improved development efficiency
  • Studio
    Next.jsDrizzleDockerEC2
    • Designed, developed, and deployed a design-system-based platform helper site for AI-driven development
    • Designed and implemented page-generation prompts and automated pipelines, reducing average feature development time from 5 days -> 1.5 days
    • Built an HTML mock generator, stepper-based guide pages, and an AI bot for assessing feature feasibility to support cross-functional collaboration
  • AI Documentation
    Claude code
    • Designed and applied documentation and prompts for AI-driven frontend development, reducing average debugging time from 1 day -> half a day
    • Analyzed existing conventions and architecture patterns to create and distribute 15+ skills and 6+ commands
    • Built a PR analysis and automation pipeline, reproducing approximately 90% of the issues identified in human review comments through comparative validation
  • Real-time Live Classroom Platform
    ReactTailwindTanStack Query
    • Developed core frontend features including Zoom Live integration, real-time quizzes, and community boards for a live training platform supporting 1,000 concurrent users
    • Embedded live lectures in the platform with Zoom Web SDK, providing a seamless one-stop learning experience
    • Optimized request flow and APIs during real-time quiz traffic spikes, reducing ECS Task average CPU utilization from 80% -> 40% based on CloudWatch
    • Stabilized and debugged quiz interaction logic requiring synchronized time limits and start times

Prosoft

Changwon, South Korea

Fullstack Engineer

23. 02. 06 - 24. 03. 01

  • Legacy Solution Re-architecture and Enhancement
    SpringBootVuePinia
    • Re-architected a Nexacro-based legacy solution with Vue 3, TypeScript, and Pinia
    • Eliminated redundant API calls and optimized API requests through asynchronous processing, improving response speed by up to 2x
    • Modularized core features including forms, grids, and search conditions to improve reusability
    • Built WebSocket notifications and drawing management features with PDF.js and Fabric.js
    • Created VitePress-based onboarding documentation to support rapid onboarding for new team members
  • DB Migration
    MyBatisOracleDBMariaDBJAVA
    • Refactored SQL statements written in Oracle DB syntax to ANSI-standard SQL, then applied and tested them in MyBatis mappers

Keywords Studio

Tokyo, Japan

LQA Tester

19. 07 - 22. 01

  • Game LQA and Onboarding Process Improvement
    RedmineMS ExcelJIRA
    • Conducted LQA for 7+ projects and supported their successful releases
    • Formed a task force amid a shortage of Korean-language personnel, supporting onboarding while testing in parallel and reducing onboarding time from 2-3 days -> 1 day

Projects

Personal Projects

Toys

Nov 2022 - Present

  • BBlog
    Next.jsTypeScriptDrizzleMySQLbetter-auth
    • Maintained a personal blog since 2022 while migrating its stack through Vue, Svelte, and Next.js
    • Built MDX articles, tag filtering and search, comments, and a Log timeline for content management
    • Separated the service architecture across a Vercel frontend, b-hub backend, MySQL, and Cloudflare R2
  • Webtoon Bookmarker
    Chrome MV3BunReactshadcn/ui
    • Developed and maintained a Chrome Web Store extension that injects a bookmark tab into the Naver Webtoon homepage
    • Built user-specific webtoon bookmark management with a Content Script, React Popup, and chrome.storage.local
    • Rebuilt v1 -> v2 with Manifest V2 -> V3, Chakra UI -> shadcn/ui, and a Vite-based build -> Bun build pipeline
  • kataru
    HonoReactCloudflareDrizzleMySQL
    • Designed and built a multi-user blog SaaS with Hono, React SSR, and an Island architecture
    • Separated user-specific subpath blogs from a CSR admin application
    • Built an HTML and Markdown bidirectional editor and a Hono-based Sharp image conversion server for Cloudflare R2
  • b-hub
    BunHonoDrizzleMySQLCloudflare R2
    • Designed and operate a backend hub that integrates 8 domains of personal services
    • Unified authentication, file processing, APIs, and scheduling with Bun, Hono, Drizzle, and MySQL
    • Implemented an RFC 4791 CalDAV server and verified core domain behavior with 1,704+ tests

Skills

Frontend

  • Next.js
  • React
  • Vue
  • TypeScript
  • Tailwind CSS
  • TanStack Query
  • Storybook
  • Electron

Backend

  • Hono
  • Spring Boot
  • Drizzle ORM
  • JPA
  • MyBatis
  • MySQL
  • MariaDB
  • SQLite

Cloud

  • AWS ECS
  • AWS Lightsail
  • Vercel
  • Cloudflare R2

Infrastructure

  • Docker
  • Debian/RHEL Linux
  • Nginx

etc.

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