- 415.952.9595 | visualharry@gmail.com | San Diego, CA 92101
- Unusual Career. Unusual Life
I've done a lot of different things in my life, professional or otherwise. Many people will view this as a negative trait. My unusual experiences, however, give me a rather unique perspective on many different things. Because of my diverse experience, I am also a very fast learner. I can pick up pretty much any new knowledge and skills, much faster than many other people.
- Unique Experience. Unique Skills
I can bring something unique to your team. I am a real problem solver. I am good at, and truly enjoy, figuring out difficult problems, often from different and unconventional viewpoints. On the flip side, I am also very good at mundane and repetitive tasks, which most people dread. I am also a clean and meticulous coder. In this age of AI/LLM, and vibe coding, does good code, and good design/architecture, still matter? I believe so, and I hope you agree with me.
- AI/LLM Development and Context Engineering
I've been doing LLM app development recently, for the last year or so. I think I've learned quite a bit in a short amount of time, and now I have my own perspective on this rapidly evolving technology. LLM Chatbot, Prompting, LangChain, LangGraph, LlamaIndex, Pydantic AI, Ollama, Llama.cpp, Transformers, Fine tuning, Unsloth, RAG, MCP, AI agent, Deep research, Evals, Embeddings, Vector DB, Chroma, Qdrant, Weaviate, Pinecone, OpenAI API, Whisper, Whisper.cpp, LiveKit, Pipecat, Vibe coding.
- Fullstack Web Development, Backend and Frontend
I've been doing Web app development pretty much my entire life. FastAPI, Flask, Django, Node.js, Express.js, NestJS, ASP.Net, Actix Web, Axum, Java Spring Boot, Ruby on Rails, Laravel, Vite, React, Next.js, Angular, Vue.js, Jest, PyTest, Tailwind CSS, Shadcn UI, Material UI, Chrome extension, PostgresSQL, Supabase, MongoDB, Redis, SQLite, Prisma, SQLAlchemy, Entity Framework, Dapper, Diesel, REST API, GraphQL, Graphene, Web Assembly (Wasm), Apache HTTP server, Nginx, Web scraping, Selenium, Puppeteer, PlayWright, Cheerio, Scrapy, Crawl4AI.
- Cloud-Native App Development and DevOps
I've been using various services of Amazon Web Services (AWS) and Google Cloud Platform (GCP) for many years now. Docker, Docker compose, Kubernetes, AWS Lambda, Step Functions, RDS, Aurora, DynamoDB, Google Cloud Run, Cloud Run Function, CloudSQL, Firestore, CI/CD, CDK (Typescript), CloudFormation, Terraform, Grafana, Prometheus, Github Actions, IAM, VPC, EC2, ELB, EKS, ECS, SQS, SNS, EventBridge, API Gateway, Google App Engine (GAE), Google Compute Engine (GCE), Google Kubernetes Engine (GKE), BigTable, BigQuery, Vertex AI, AWS SageMaker, Azure Cosmos DB, Azure Functions, Azure Kubernetes Service (AKS).
- Mobile App Development
I did Android app development for many years in the mid- and late-2010s. I also did some AR/VR app development. Android, Google Glass, Microsoft HoloLens, React Native/Expo, PhoneGap/Cordova, Ionic, Flutter, Unity3D (C#), Unreal (C++), Qt.
- Machine Learning, NLP, Computer Vision
I did research on machine learning many years ago, as a postdoc. I am also familiar with most of the "standard" deep learning/ML tools and libraries. PyTorch, TensorFlow, Scikit-Learn, NLTK, SpaCy, NumPy, Pandas, MatPlotLib, Seaborn, OpenCV, Tesseract OCR, Hugging Face, Data analysis, Big data, ETL, Apache Spark, Kafka, Airflow, Hadoop.
- Programming Languages
I've used many different programming languages over the years, partly because of the job requirements, and partly because of my curiosity and passion for learning. C/C++, C#, Go, Python, Javascript, Typescript, Rust, Java, Scala, Kotlin, Julia, Ruby, Lua, Haskell, Erlang, Clojure, PHP, Perl, etc.
- Sr. Fullstack Developer, OpenTable, 2018-2019.
Migrated the old photo/image server written in Clojure into C#/ASP.Net Core. Implemented a new media metadata API server in C#/.Net. Created a number of media-serving React components for the OpenTable website (Typescript).
- Sr. Backend Developer, Yahoo!, 2007-2010.
Created an automatic keyword generator, for the Yahoo Small Business customers, based on their sales and Web search data. Implemented a KPI dashboard using the internal business data for the upper management. Created a rule engine to automatically update the business logic based on Yahoo SMB's business requirements. Worked on the checkout system (PHP), and re-designed and re-implemented its API service, according to the REST paradigm.
- Sr. Software Developer, PeopleSoft, 2004-2005.
I was part of a core team which worked on creating a new infrastructure to help the engineering migrate PeopleSoft's HR apps to the Web. I was primarily responsible for the "data table" component, in C++/Javascript.
- Software Developer, Brio Software, 2000-2003.
I Participated in the migration of the legacy desktop BI app to the newly designed BI Web service in C++. Also worked on both frontend and backend layers of a new "thin client" Web app, in Java and Java Servlet/JSP, which was a company-wide project.
- Ph.D. in Physics, 1995
University of California, Santa Cruz, CA.
- M.S. in Physics, 1990
Pohang Institute of Science and Technology, Pohang, Korea.
- B.A. in Electronics Engineering, 1988
Seoul National University, Seoul, Korea.
- Inventions and Patents (2005-2012)
I was awarded four United States patents in the areas of business methods and software. I am also a registered patent agent before the U.S. Patent and Trademark Office. I briefly worked at an IP law firm in Silicon Valley prosecuting patent applications on behalf of companies like Apple and Cisco.
- Book Publications (2021-2025)
I wrote a number of books on the subjects of physics and programming. Most of my books on programming, on Python, Go, Rust, etc., ranked as Amazon "bestsellers" in their respective categories. I've also been working, for the last few years, on translating Einstein's original papers and other articles in German to modern English. Only a small portion of them have been published so far, and the project is currently on hold (due to financial reasons :]).