Software Engineer · Seoul, Korea
Building tools for urban intelligence, prediction systems, and open-source infrastructure. Focused on making complex data accessible and actionable.
Urban Data Systems · 2023 – Present
Leading development of a city-scale API platform serving 142 cities globally. Architected real-time data pipeline processing 2M+ events daily with sub-200ms latency.
Prediction Labs · 2021 – 2023
Built calibrated forecasting engine and crowd prediction aggregation system. Improved model accuracy by 34% through ensemble calibration techniques.
OpenStack Korea · 2019 – 2021
Contributed to open-source cloud infrastructure tooling. Authored 12 merged PRs to core modules and maintained community documentation.
Open-source TypeScript SDK for city data APIs. Used by 60+ developers across 18 organizations to build urban analytics dashboards.
Calibrated ensemble prediction engine processing crowd forecasts into actionable probability distributions with 94% calibration accuracy.
YongJoon brings rare depth to API design. The xity-sdk is one of the cleanest developer experiences I have worked with.
His forecasting work transformed how we handle uncertainty. The calibration improvements alone saved us months of iteration.
Consistently delivers well-architected, thoroughly documented systems. A rare combination of engineering depth and communication clarity.
Whether you are hiring, exploring a collaboration, or have an interesting project in mind, I would love to hear from you.