Seunghwi Heo(Harry)

Sajo Systems is a company that manages IT systems for partner companies within the group SAJO

1. Web Order System Maintenance & Enhancement

• Developed new features and menus based on client requirements to improve usability
• Improved system stability by resolving bugs and handling incidents
• Enhanced UI/UX for better user experience
• Integrated SAP ERP (SD module) and WMS logistics system

2. Legacy EDI System Migration to Cloud (1 month)

• Migrated legacy EDI system to a cloud-based infrastructure
• Optimized data transmission for better performance and scalability
• Refactored database layout and procedures for cloud compatibility

3. Web Application Server (WAS) Expansion (1 month)

• Implemented load balancing for better system scalability
• Modified source code to support server expansion

4. Oracle Database Upgrade (3 months)

• Upgraded Oracle DB from 10g to 19c and migrated all data
• Refactored SQL queries and database objects for compatibility
• Conducted post-migration issue handling and system stabilization

5. Web Security Hardening (2 months)

• Resolved major vulnerabilities (SQL Injection, XSS)
• Strengthened encryption and access control for data protection
• Reinforced file upload/download security policy

6. IT Audit Preparation (semi-annual)

• Handled documentation and monitoring for internal/external audits
• Operated logging and monitoring systems; enforced compliance improvements

7. Automated Server Failure Recovery System (2 months)

• Developed automated backup and recovery system for operational downtime
• Minimized downtime through real-time data sync features

8. Python Automation Tools

• Built automated server monitoring tool using Python & Selenium
• Developed web crawlers for market analysis (e.g., Coupang product reviews, livestock prices)

9. Address Validation API via Excel Macro

• Created Excel macro logic to validate delivery addresses
• Reduced user input errors and prevented system memory overload