DJAbout Dongyoun
Performance-Driven Java Backend Engineer | 4.8 Years Exp. | Partner of LG CNS & LG Electronics | AI/MLOps Integration Specialist
Summary:
Proactive Backend Engineer specializing in scalable microservices and legacy system optimization. With 4.8 years of experience , I have a proven track record of migrating Monoliths to Microservices (MSA), handling 20x traffic spikes, and integrating LLMs into production workflows. I combine deep expertise in Java/Spring Boot with modern AI/MLOps capabilities to deliver high-performance solutions. Ready for on-site roles in Berlin starting January 2026.
Key Experience & Achievements:
1. Backend Developer | Egistech * 20x Performance Boost: Re-architected authentication modules and optimized DB Connection Pools, scaling concurrent capacity from 100 to 2,000+ users. * AI-Assisted Migration: Used LLMs to convert 1,000+ lines of legacy Stored Procedures to MyBatis, reducing lead time by 50%.
2. Full-Stack Developer | Widetns (Partner of LG CNS & LG Electronics) * MSA Transition: Spearheaded the transition of core platforms to Spring Boot Microservices using Feign Client and Kafka. * SSO & Security: Architected a secure OAuth 2.0 SSO system using Quarkus and Keycloak across 4+ enterprise applications. * Complex Migration: Ensured data consistency during an Oracle-to-MySQL migration of millions of records using the Saga Pattern.
Key Engineering Projects:
- Asgard: Lead Architect for an enterprise AI Microservices platform using Event-Driven Architecture to decouple workloads. * Papyr.us: Engineered a real-time collaboration tool using CRDTs and integrated RAG for "Chat with Wiki" features.
Tech Stack:
- Backend: Java 17, Spring Boot 3.2, Spring Cloud, Quarkus, JPA/Hibernate. * AI & Data: OpenAI API, RAG, Vector Search, Redis, PostgreSQL, Elasticsearch. * Infrastructure: Kafka, Kubernetes (K8s), Docker, GitHub Actions, AWS.
Korean
Native or bilingual
English
Conversational
Can work on-site
Berlin (up to 50km)
Experience
- EgistechBackend DeveloperJune 2025 - October 2025 (4 months)Seoul, South KoreaSuccessfully modernized legacy public sector systems through AI-assisted engineering. 20x Performance Boost: Re-architected authentication modules and optimized DB Connection Pools, scaling concurrent user capacity from 100 to 2,000+. AI-Driven Migration: Utilized LLMs to analyze and convert 1,000+ lines of legacy Stored Procedures into MyBatis, reducing migration lead time by 50%. Documentation Pipeline: Standardized API specs using Swagger/OpenAPI, enhancing collaboration between frontend and backend teams.
- Widetns(PartnerofLGCNS&LGElectronics)Full-Stack DeveloperDIGITAL AND ITFebruary 2021 - May 2025 (4 years and 3 months)Seoul, South KoreaLed core backend development for enterprise-grade projects with high availability requirements. Monolith to MSA Migration: Spearheaded the transition of a core platform to Spring Boot Microservices, decoupling dependencies using Feign Client and Kafka. SSO Implementation: Architected a secure OAuth 2.0 Single Sign-On system using Quarkus and Keycloak, unifying access across 4 + enterprise applications. Performance Tuning: Reduced API latency by 30% through advanced query tuning and JVM optimization during peak traffic periods. Distributed Transactions: Implemented the Saga Pattern to ensure data consistency during a critical Oracle-to-MySQL migration involving millions of records.
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Education
- B.S. inKoreaNationalOpenUniversity2025B.S. in
- B.A. in EconomicsIncheonNationalUniversity2021B.A. in Economics