Junghyun Nam (남정현)

Seoul National University 2019.03 ~ leave in absense

Currently on undergraduate courses majoring in Computer Science & Engineering.

• GPA: 3.9/4.3 (not finalized)
• Credits: 45/41 (not finalized)

Also double-majoring in Statistics.

Sejong Science High School 2016.03 ~ 2019.02

Hyperithm (https://hyperithm.com) 2021.08 ~ current

Hyperithm is a leading digital assets manager in Asia, based on Japan and Korea.

• Head of Infrastructure
• Maintaining the overall cloud infrastructure based on AWS and GCP.
• Developed and maintaining a HFT-optimized cryptocurrency exchanges data feed.
  • Keywords: Asynchronous Programming, Rust, Tokio, HTTP, WebSocket.
• Maintaining additional infrastructures like L7 proxy clusters for the cryptocurrency data feed.
  • Keywords: NGINX, AWS ECS
• Designed & managed development of a trading strategy management infrastructure.
  • (think stripped-down version of ECS or EKS with some internal niche feature demands).
  • Keywords: Rust, AWS CloudFormation, AWS S3
• Developed & maintaining an DevOps toolkit for AWS infrastructures, featuring seamless 1Password integration with AWS credentials management.
  • Keywords: Rust, Clap, AWS SSM

Research Intern at CARES Lab 2021.03.26 ~ 2021.06.30

Started as SNU UROP(undergraduate research opportunities program) on February, then switched to paid intern on March.

Worked on RustFTL, a (partial) Rust port of the FEMU SSD emulator.

Rewrote FTL(flash translation layer) part of FEMU into Rust and reported about use of Rust on embedded systems focusing on safety, performace impact, and idiomacy of Rust code on FTL structures.

The final report and documentation were constructed with mdBook and rustdoc.

Engineering Intern at CN.AI 2020.08.01 ~ 2020.08.28

Constructed data pipeline for deep audio classifier with PyO3 and HDF5 to boost training speed.

Developed a demo website with StyleGAN2 which synthesizes 'median face' from given two facial images.

• The model is pretrained with FFHQ dataset on TensorFlow, and communicates with backend with a simple TCP server.
• The backend is written in Golang with its standard net/http module and the Gorilla web toolkit.
• The frontend is based on React.

Programming Languages

• Rust(primary): Tokio and related async ecosystem packages, aws-sdk-rust
• Golang: net/http, Bolt(embedded KV store)
• C
• TypeScript: Mostly React
• Python: Tkinter, requests, Bolt(Slack SDK)
• Other misc. languages w/ basic experiences: C++, Java(JVM, Android), Dart(pre-2, Flutter), OCaml

DevOps

Have managed several on-premise solutions such as Jenkins, a security management platform (private)

Experiences:

• CI/CD pipeline with AWS EC2, EC2 Image Builder, ECR, etc.
• Layer-7 HTTP proxy clusters with AWS EC2 Launch Template, ECS, ECR, etc.
• Fine-grained access control of EC2 instances with AWS Systems Manager Session Manager and IAM.

Linux & Systems Programming

Experiences:

• Embedded Linux development with Raspberry Pi(1B+, Zero W, 3B+) and Buildroot.
• Kernel hacking including implementing custom syscalls and task schedulers.

Blockchain & DeFi

Knowledges:

• General consensus mechanisms, e.g. Proof-of-Work, (naïve) Proof-of-Stake and their variants like Proof-of-History, Byzantine Fault Tolerance, etc.
• How decentralized finance works and their sub-categories: money markets, DEXes, yield aggregators, stablecoins, etc.
• Cross-chain/multi-chain/layer-2 ecosystems: Wormhole, Cosmos, Polkadot, Arbitrum, ZKSync, etc.
• Intuitive understanding of zero-knowledge proofs and their applications on blockchains.
• Invested on some of projects mentioned above.
  • Track record? Please don't ask.

Machine Learning & Computer Vision

Knowledges:

• Basic concepts like regressions and classifications, nerual networks, regularization, gradiant descent methods, etc.
• CV topics such as convolutional neural networks and their variants, autoencoders, generative adversarial networks and their variants, etc.

Full Stack Development

Experiences:

• Obviously, this résumé page.
• WebAssembly application with Rust and deploying onto a web demo page.
• Next.js applications for 1) monitoring and data visualization, 2) simple CRUD demonstration.
• Hobby-level web backend with Rust and Golang
• Serverless applications(e.g. Cloudflare Workers) with Rust and WebAssembly, which is announced for public use.

Nerf Rust, Serde, Tokio, Tower, Hyper, HTTP

A HTTP request framework with tower-rs intergration.

Its main purpose is to do an experiment about refactoring a company-private cryptocurrency exchanges API into composable tower::Layers, achieving:

• Switchable HTTP client backends.
• Configurable rate limits (provided by tower-rs).
• Multiplexed HTTP clients (provided by tower-rs).
• Mock testing paired with axum.
• Automatic throttling based on API responses with remaining rate limits (TODO).

lzn Rust, Web Scraper, SQLite, Diesel ORM

A Lezhin/Naver Webtoon scraper. Was private in the past for ethical reasons, and made public recently as the bot protection mechanism has changed so the scraper is not working. Only saves 'free' episodes.

Features:

• SQLite-backed storage (may be easily switchable into other RDBs e.g. Postgres/MySQL/etc.)
• Embedded web server for local use.
• Performs authentication to bypass some protections on CDN.
• Exports into comic viewer formats(basically zipped sequence of images).

LC-3 Toolsets Rust, LC-3, CLI, WebAssembly, PEG

A Rust implementation of Little Computer-3 tools, including:

• lc3-rs: A LC-3 ISA implementation(simulator).
• lc3dbg: A command-line debugger with mem/reg inspection and rewinding.
• lc3asm: An full-featured LC-3 assembler.
• lc3p2atest: Fuzzer for Computer Concepts undergraduate course's project #2 assignment.
• lc3web: WASM-compiled LC-3 playground on browser. Try it online

Kaimak ES2015 Proxy, Web3(Metamask), Chrome Extension

A Kaikas-Metamask bridge Chrome extension. Its purpose is to use the Ledger hardware wallet with Kaikas extension on Klaytn DApps, as most of which do not support Metamask.

pc.cro.sh Cloudflare Workers, Rust, WebAssembly, React, Material UI

A MapleStory(an online MMORPG game) settings store. Technically this is a public key-value store with:

• Data validation(should be a valid game configuration with windows registry export format)
• AES-256 data encryption, performed only on client side with WASM(the configuration seems to store somewhat sensitive information)
• Bot protection with reCAPTCHA V2
• Cloudflare Workers & Workers KV backed: capital efficiency
• Material style web UI

find.cro.sh TypeScript, React, Fuse.js, Web Scraping, Chrome Extension

An inventory/storage search engine for MapleStory.

This service consists of two components:

• A Chrome extension which indexes the user's account inventories/storage items via script injection. The index is then exported into JSON.
• find.cro.sh: a React webapp which fuzzy-searches the items of an imported index.

zandam Rust, WebAssembly

A generator of encrypted self-extracting single-file HTML documents with an embedded WebAssembly blob. Predecessor of pc.cro.sh.

Writeup available in Korean: https://blog.cro.sh/posts/embedding-wasm-in-html

Introduction to NIZK Proofs

https://blog.cro.sh/slides/introduction-to-nizk-proofs-20220307.pdf

Rust 비동기 프로그래밍 (Asynchronous Rust Programming)

https://blog.cro.sh/slides/async-rust-programming-20220801-redistributable.pdf