• refresh.cv

  • Drove zero-to-one across product, architecture, full-stack engineering, UX design, data analytics, and GTM/sales

  • Shipped resume editor with agent-based resume authoring, revision, and feedback

  • Launched resume scoring and feedback based job description

  • Delivered resume web templates and resume card components

• Toss Ads

  • Built and operated ad platform used in 15M+ MAU Toss app for campaign execution, review, and performance

  • Implemented ad performance ingestion/aggregation (impressions, clicks, plays) with Kafka, Druid, Impala

  • Implemented real-time CPM/CPC billing; ensured data integrity at scale with local cache + flush pattern

  • Contributed to settlements, agency commission payouts, and tax invoice issuance

  • Shipped ad account/group systems and integrated with Toss Business

• Display Ads product (monthly 10B+ KRW scale)

  • Contributed to eCPM-based ad recommendation and ranking improvements, driving >1B KRW monthly uplift

  • Implemented multiple optimization strategies to minimize ad refresh and serving latency, improving both UX and fill rate.

  • Implemented CPC (cost-per-click) and CPM (cost-per-mille) billing logic end-to-end for our ad serving pipeline.

  • Built real-time dashboards and alerting to monitor impressions, clicks, and spend in production, catching ad-serving incidents before they impact revenue

• Live Shopping

  • Optimized performance with tens of thousands of peak RPS without degrading UX using Local Cache, Redis and Kafka optimizations

  • Authored article on handling large-scale traffic without adding servers

• Credit Score Board

  • Built product aligned to financial context and user comprehension

• Benefits Tab (8M+ DAU)

  • Shipped Lucky Quiz, Lucky Lottery, Money Alerts, and Weekly Missions

  • Owned product development and operations from advertiser and user perspectives

founding team; leading product roadmap and led a 10-engineer team

• Evoclass: real-time video conference platform

  • Implemented WebRTC SFU with Mediasoup and high-performance socket servers using uWebSockets

  • Built server orchestrator and demand forecasting to reduce streaming cost and ensure efficiency

  • Created container-based load testing to guarantee real-time video/audio QoS and performance

  • Delivered real-time STT and translation via browser-native APIs

  • Built AI-powered video effects: background blur, virtual background, face morphing

• Learning Management System

  • Designed and implemented system architecture

  • Integrated with the video platform to enable AI-driven learning features

• Admitted via special talent track

• Developer, SPARCS student open-source club (sparcs.org)

• GPA: 3.87/4.3

• Admitted via contest winner track (KOI)

• Graduated 1st in IT Literacy Certification Program

• Kernel360 cohorts 1-3: Frontend mentor

• InnerCircle cohorts 2–3: Frontend mentor

• InnerCircle cohort 4: Backend mentor

• Produced course: Remix Fundamentals — faster, pragmatic web development with performance optimization

• Built back-office admin web dashboard for Mopl, an apartment management solution using Remix

• Improved code quality and stability via functional programming (e.g., currying) and robust TypeScript generics

• Implemented scalable, fast rendering using TanStack Headless UI

• Frontend code reviewer for the 7th cohort

• Full-stack code reviewer for the 10th cohort

Write-up summarizing troubleshooting while building and operating the “Live Shopping” product in the Toss Benefits tab.

Published in the Proceedings of HCIK 2021

Hosted by the HCI Society of Korea