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SimpleHAN

Dev Team Backend Engineer

2021-07 — 2022-03

Custom software consulting firm

Highlights

  • Developed LMS core features (QR attendance, PDF certificates, Excel bulk registration) full-stack over 10 months, digitizing learning management for 300+ students per semester
  • Overcame legacy PHP system limitations via cross-frame integration, implementing weighted matching algorithm and counselor back-office to launch JOB Agent service
  • Built cross-domain auth server to unify login across 5 country-specific websites into a single authentication system

Projects

Learning Management System (LMS) Development

2021.07 ~ 2022.03

Resolved manual learning management (attendance, completion, progress) causing low operational efficiency and frequent errors at educational institutions

  • QR Attendance: Built real-time attendance API with date+userID composite unique key preventing duplicate check-ins
  • Excel Bulk Registration: Apache POI-based row-by-row sequential processing ensuring data consistency for batch member registration
  • Developed LMS core learning features including board CRUD, video upload, and progress tracking
  • Dynamic Certificate: JasperReports-based PDF auto-generation API
Java Spring Boot MyBatis MySQL Apache POI JasperReports

Incheon Smart Green Industrial Complex Control Center

2022.01 ~ 2022.03

Resolved fragmented reservation, monitoring, and SMS systems preventing unified management at industrial complex control center

  • Reservation System: Built real-time booking API with time+location composite unique key preventing scheduling conflicts
  • Dashboard API: Integrated monitoring data and status aggregation
  • Async SMS: Bizppurio SMS API + @Async non-blocking reservation confirmation notifications
Java Spring Boot MySQL Bizppurio SMS API

Future Service JOB Agent Development

2021.07 ~ 2022.03

Resolved legacy PHP system's extensibility limitations and lack of structured scoring and counseling management

  • iframe Integration: Embedded Spring Boot independent app into existing PHP system, minimizing legacy impact
  • Implemented postMessage API-based cross-frame real-time state synchronization
  • Composite Scoring: Weighted average-based multi-dimensional assessment scoring algorithm
  • Counselor Back-office System: Counseling history management and dashboard
Java Spring Boot MySQL

kfriends Member Management System

2021.09 (3 weeks)

Resolved lack of unified authentication requiring separate logins across 5 country-specific distributed websites

  • Unified Auth Server: Spring Security + JWT-based centralized authentication
  • Multi-domain CORS Handling: Secure token exchange across country-specific domains
Java Spring Boot Spring Security JWT MySQL

Internal Tech Blog Renewal

2021.09 (3 weeks)

Resolved hosting cost burden and manual deployment workflow of WordPress-based blog

  • WordPress → Jekyll Migration: Static site conversion eliminating 100% hosting costs
  • GitHub Pages + Travis CI: Git push-based automated build and deploy pipeline
Jekyll Liquid Travis CI GitHub Pages

Technical Skills

Java Spring Boot Spring Security MySQL MyBatis Apache POI JasperReports AWS EC2 RDS S3 Travis CI Jekyll JWT GitHub Pages