Does Using UUID as PK Hurt Index Performance?
Code Review Comment While implementing the Gift API at Kakao Tech Campus, I used UUID as the member identifier. My mentor left this comment during code review: “Since you’re using UUID, you mi...
Junyoung Yang
Select-then-Update vs Single Update: What Matters More Than Performance
The Question At Kakao Tech Campus, I was implementing member profile update with JDBC Template. Mentor gave me this feedback: “Even if a field value hasn’t changed, you’re updating it to the s...
Building a RAG Pipeline to Reduce LLM Hallucination
Problem Participated in “PNU x Upstage Document AI Challenge 2025” and developed “DocDoc,” a medical AI assistant for overseas medical teams. The core feature was “paper search and summarization....
Android Fragment Lifecycle and savedInstanceState Debugging
Background In high school, I developed an app called “Dongcheon Alimi” for fellow students. It was a convenience app providing meal info, timetables, announcements, etc. One day, users started re...
Building a TCP/IP Socket Server for IoT Smart Lighting
Project Background I participated in the 1st Woosong University National SW Club Competition and built an IoT smart lighting system. The system automatically adjusts light brightness based on ambi...