Cho Il-hwan

Developer

Fifteen years building data platforms. Now building the products and tools I use myself.

A developer with fifteen years of experience, from very large data infrastructure to LLM-based AI service architecture.

I designed and operated real-time ETL pipelines and data platforms handling 15 billion unstructured records (300TB+). I moved on-premises resources to Kubernetes-based SaaS/PaaS, improving infrastructure efficiency by more than 400%, and led the rollout and operation of generative AI services by designing an LLM gateway API and the backend of an AI search service.

Experience

  1. 2025 – Present

    Tigerface

    Platform Lead

    Leading internal platform development at a logistics company.

  2. May 2018 – Oct 2025

    SK Telecom

    Data Platform Architect · Search Infrastructure Team / PaaS Division

    Designed data platform architecture and advanced the infrastructure behind an AI search service.

    • Built the PaaS and LLM gateway architecture for a conversational AI search serviceTo cut external web-crawl latency (3.2s+) and P99 timeouts (3.8%), added a two-tier Redis cache in front of the collection engine and pre-validation at the gateway. Reduced external API cost by 81.6%, average response latency from 3.2s to 850ms (73% faster), and the P99 error rate to under 0.08%.
    • Removed bottlenecks in and re-architected a very large real-time ETL platform for unstructured dataResolved a 78 TPS bottleneck and 499 timeouts (12.4%) that appeared while processing 15 billion records (300TB+), using a CompletableFuture-based asynchronous outbox and G1GC IHOP tuning. Raised ingest throughput from 78 to 450+ TPS (5.7x), eliminated 99.8% of 499 timeout failures, and cut the G1GC maximum pause from 1.5s to 120ms (92% shorter).
    • Built a self-service SaaS for provisioning Kubernetes middleware and expanded the control plane to a five-node quorumFixed control-plane stalls caused by etcd I/O latency (45ms) by expanding etcd to a five-node quorum and moving it to NVMe, lowering P99 write latency from 45ms to 4ms (91% shorter). Built an on-premises SaaS that deploys Kafka and Redis within five minutes, cutting provisioning time from 48 hours to 5 minutes and raising cluster resource utilization from 10% to 52%.
    • Kubernetes
    • Kafka
    • HBase
    • Redis
    • Spark
    • Java
    • Kotlin
    • Python

  3. Jun 2017 – May 2018

    KakaoPay

    Backend Developer · Payment Team

    Developed the payment system backend and stabilized settlement data.

    • Handling large-scale payment trafficDeveloped a highly available, low-latency payment authorization backend and built a pipeline that isolates failures with circuit breakers and failover.
    • Improving the settlement systemImproved the pipeline that automatically reconciles millions of payment logs, bringing the settlement error rate to 0%.

  4. Oct 2012 – Jun 2017

    Kakao

    Software Developer · Search Team, Search Spam Cell

    Developed spam detection systems and a data analysis platform to improve search quality.

    • Anti-spam systemBuilt a fingerprint engine that filters abusive macros and spam traffic out of large volumes of real-time search impression and click data.
    • Large-scale data warehouse infrastructureBuilt a spam-pattern analysis data warehouse on HBase and Hadoop/Spark and operated large-scale log analysis pipelines.
    • HBase
    • Hadoop
    • Spark

  5. Sep 2010 – Oct 2011

    enSalt

    Co-Founder · Server-side Developer

    As an early startup member, led web service architecture design and core engine development.

    • Software for media art projectsFor media art projects including “LifeCycle”, “Hana Bank Flagship Store”, “Thumb Vote”, “You Know What” and “Social Pixel”, implemented software running on embedded processors and the social network services connected to it.

Skills

Languages
  • Java
  • Kotlin
  • Python
  • Go
Data & Infrastructure
  • Kubernetes
  • Kafka
  • HBase
  • Redis
  • Spark
  • Airflow
AI & Search
  • LLM Gateway
  • Vector Database
  • RAG
  • ElasticSearch
DevOps & Tools
  • Docker
  • Datadog
  • Git
  • CI/CD Pipelines

Projects

  • Phase 1 delivered

    Agent Mission Control

    A local-first macOS app that shows the state of multiple coding agents as pixel characters and manages their work on a task board.

    • Electron
    • SQLite
    • TypeScript

Tools

All tools

Education

  • 2010.11

    Handong Global University

    B.S., School of Computer Science and Electrical Engineering

  • 2003.12

    Sokcho High School

    Natural sciences track

Certificates

  • 2024.03

    AWS Certified Developer · Amazon

  • 2009.03

    SCBCD · Sun

  • 2008.08

    SCWCD · Sun

  • 2008.04

    SCJP · Sun

  • 2006.06

    Engineer Information Processing · HRD Korea