Summary

• Experienced software engineer with a passion for distributed systems, scalability problems, and dealing with a large amount of data
• Another area of interest is internal tools development to boost the productivity of colleagues
• Keeps communication skills honed by actively engaging in conversations, public speeches, and ritually writing daily journals and various social media posts of substantial lengths

Work Experience

Senior Software Engineer @Coupang

Data Engineering

• Kafka log persistence
• Kafka schema registry
• Handling extract, transform, load (ETL) tasks with Spark

Inter-domain logistics state management system (Flow)

• Handling write-heavy workloads with Cassandra
• Message ordering guarantee with a distributed queue
• RESTful API for internal customers (domain teams)
• Spark jobs for data validation, written in Scala, fully automated with Airflow

Internal Tools & Extracurricular Activities

• awsauth: Command line tool written in Golang to issue temporary AWS access keys with AD FS and AWS STS
• schema-extractor: Command line tool to generate an ORC schema from a Java DTO class using reflection.
• Leading an unofficially-organized class to teach Python to colleagues

Software Engineer @Nexon

Marketplace

• In-game marketplace where players exchange goods with money and vice versa
• Inter-database transactions (Couchbase ↔︎ AWS Aurora)
• Complex search query support with Elasticsearch
• Driving most of technical decisions

Ecosystem Simulator & Pipeline

• In-game natural environment that resembles that of the real world
• Number crunching with OpenCL and C# math library
• ECS, ECR, data pipeline
• Cost saving (est. $300,000/year) with architectural revisions
• Implementing precautionary measures: data validator, auto-scaling
• Public speech on this topic: Automating Mother Nature @AWS re:Invent 2017

Internal Tools

• Wheelhouse: Automated Python package pre-build system for internal PyPI repository
• Game world packaging and distribution tools for internal customers (game designers, non-tech users)

Software Engineer @Spoqa

• Building a customer-facing Android app
• Building a backend for commercial loyalty service

Research Programmer @University of Arizona

Jun 2010 - Jun 2011, Tucson, AZ

• Developed internal tools to conduct machine learning researches

Education

MS in Computer Science @University of Arizona

BS in Computer Science, Mathematics @University of Arizona

Postgraduate Education

• Occasionally, but persistently taking classes from Coursera, Udacity
  • Machine Learning
  • Design of Computer Programs
  • Computational Finance
• Founding and leading an unofficial research paper reading group in Nexon (2015)

Public Speeches

AWS re:Invent 2017: Automating Mother Nature

Discussed the architecture that we settled on for algorithmic generation of game content in a large scale with a number of components provided by Amazon Web Services such as distributed messaging queues (SQS), containerized application clusters (ECS), and object storages (S3).

Nexon Developers Conference 2016: Automated Game Terrain Management for Durango

Discussed how we built an automated pipeline to supply natural resources. Due to the sheer size of the in-game world, the environment simulation is performed on-demand, within a limited geographic boundary, in accordance with player activities.

Nexon Developers Conference 2015: Natural Environment Simulation for Durango

Discussed how we built an in-game environment simulator with OpenCL to handle a massive parallel processing. The primary purpose of the simulator is to provide natural resources based on realistic simulations by taking a number of geographic features, such as topography, temperature, humidity, soil fertility, into consideration.

Patents & Research Papers

Patent #1020160025511: A system for simulating a game environment (Mar 2016)

Nexon decided to file a patent with the work referred above as natural environment simulation. I was listed as a co-author along with the game designer who pioneered the concept.

Human Natural Instruction of a Simulated Electronic Student (Jan 2011)

Discusses how human-instructable computing can be achieved. That is, how an electronic student can be taught using the same natural instruction methods humans use.

Open Source Activities

Contributions to others

• pandas-datareader: Extract data from a wide range of Internet sources into a pandas DataFrame.
• secor: Kafka log persistence.
• gspread: A Python library to access and manipulate Google Spreadsheets.

My own projects

• Hanja: A Python library to read Chinese characters in Korean sound values.
• Winnowing: A Python implementation of local algorithms for document fingerprinting.
• Base62: A Python library to encode and decode any arbitrary data in base62 (duosexagesimal; using 0-9, A-Z, and a-z) for URL-safety. I was recently able to convince my colleagues to use this library for work.
• And more on my GitHub page

Personal Projects

Dollar Auction

An improvised marketplace to sell underused personal belongings where every auction starts at KRW 1,000 (approximately USD 1).

SB Finance

Set of code for personal asset management and quantitative investment.

Volunteer Works

BOINC

Providing 127GFLOPs on average to tackle difficult scientific problems such as climate modeling, discovering large prime numbers, and generating accurate three-dimensional dynamic models of stellar streams in the immediate vicinity of the Milky Way galaxy.

Radioactivity (Discontinued)

This project had started in March of 2011 in an attempt to help the general public to be alerted regarding the spread of radiation and other radioactive materials originated from the catastrophic incident in the Fukushima nuclear power plant in Japan, by visualizing city-wise radition levels in near real time.