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Medgo

Dev Team Backend Engineer

2022-04 — 2023-05

Telemedicine and medication delivery platform startup with 300K cumulative downloads

Highlights

  • Modernized 3,000-line legacy codebase via 3-stage progressive migration (single-file → layered → NestJS) with JS→TS + 80% TDD coverage, maintaining zero post-deployment incidents
  • Resolved session conflicts across 3 subdomains on 300K-download platform by building JWT-based token authentication in 3 weeks, enabling seamless user switching
  • Automated full prescription-to-medication-guide workflow via Naver Clova OCR + MFDS (Korea FDA) API integration, cutting pharmacist processing time 90% (3-5min→30sec)
  • Introduced Socket.IO-based real-time status sync + Web Push notifications, reducing status reflection delay from tens of seconds to instant and eliminating patient wait complaints

Projects

Auth Server Development

2022.04 (3 weeks)

Built JWT-based unified authentication system to resolve subdomain session conflicts

  • Designed and implemented NestJS + JWT token authentication system
  • Migrated from session-based to token-based auth for seamless subdomain user transitions
  • MySQL-based JWT key management (infrastructure simplification over Redis)
  • Access Token + Refresh Token dual token structure
  • Unified authentication for web (doctor/pharmacist/admin) + mobile app
NestJS TypeScript JWT MySQL

Common Module Development

2022.05 ~ 2022.06

Resolved code duplication and inconsistency from independent service management by consolidating shared modules

  • Built error log notification module for system monitoring efficiency
  • Implemented user permission verification middleware for security enhancement
NestJS TypeScript

Doctor/Pharmacist Web Service Enhancement

2022.04 ~ 2023.05

Resolved lack of real-time status updates and manual notification workflows in doctor/pharmacist back-office systems by introducing Socket.io and Web Push

  • Doctor ID + time slot composite unique key preventing duplicate appointments
  • Extended existing consultation request→doctor approval flow by adding per-doctor availability management and appointment booking to enhance the scheduling system
  • Socket.IO Room-based real-time status sync reflecting consultation/dispensing/delivery events to relevant users instantly
  • Reduced status reflection delay from tens of seconds to instant, eliminating patient wait complaints
  • VAPID + Service Worker-based background notifications for instant appointment and dispensing alerts even when browser is inactive
  • Integrated Kakao simple login and identity verification
  • Enhanced admin dashboard for operational monitoring
  • Built internal API gateway integrating delivery (Hoodadak) and payment external services with Circuit Breaker pattern for fault isolation
  • Implemented real-time error monitoring system via Discord webhooks
Express.js NestJS TypeScript EJS MySQL Socket.io Web Push

Prescription OCR & Medication Guide System

2022.11 ~ 2022.12

Automated pharmacist's manual prescription entry process using OCR

  • Integrated Naver Clova OCR API for automatic text extraction from prescription images
  • Built structured data pipeline for automatic system entry
  • Developed automated medication guide generation using MFDS (Korea FDA) drug information API
  • Reduced pharmacist processing time from 3-5 minutes to under 30 seconds per prescription
NestJS TypeScript Naver Clova OCR MySQL

Backend Architecture Migration

2023.03 ~ 2023.05

Migrated from Express.js single-file (app.js) structure to NestJS modular architecture

  • 3-phase incremental migration: app.js single file → Layered Architecture (Controller/Service/Repository) → NestJS framework adoption
  • JavaScript → TypeScript migration for type safety
  • Introduced TDD and achieved 80% unit test coverage
NestJS TypeScript TypeORM Jest MySQL

Technical Skills

NestJS Express.js TypeScript TypeORM EJS MySQL JWT Socket.io Web Push Naver Clova OCR Jest