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jjinyy/README.md

Hi, I'm Hyejin (Jinny)

I'm an AI/software engineer interested in building intelligent systems that work beyond the prototype.

My work spans AI agents, LLM systems, retrieval, applied ML, reinforcement learning, and full-stack AI applications — from experimenting with models and architectures to building APIs, evaluation pipelines, and production integrations.

I enjoy problems where the right solution isn't obvious at the start: understanding the problem structure, choosing the right technical approach, building the system end-to-end, and testing whether it actually works.

I've worked across 20+ projects in manufacturing, logistics, pharma, and distribution, and have built AI systems in both client-facing and enterprise environments across Korea, Malaysia, Singapore, Thailand, Brazil, and the US.

Currently exploring AI agents, AI for software engineering, retrieval & evidence-grounded reasoning, evaluation, and reliable AI systems.


Selected Projects

An AI agent that investigates production incidents across a synthetic microservice environment.

Uses native tool calling to inspect logs, metrics, distributed traces, deployments, configuration changes, dependencies, and runbooks.

Built fault-injection scenarios for deployment regressions, dependency failures, bad configurations, connection-pool exhaustion, and traffic spikes — with evidence validation, bounded investigation loops, human approval for high-risk remediation, and stateful recovery verification.

Python FastAPI LLM Tool Calling Distributed Tracing Agent Evaluation


A research-inspired fault-localization system based on the AutoFL approach.

Given a stack trace, ranks the functions most likely to contain the bug using AST-level code chunking, hybrid keyword + embedding retrieval, and optional Claude reranking.

Achieved 100% Top-1 / Top-5 retrieval accuracy on a 5-case controlled benchmark, with automated evaluation through GitHub Actions.

Python AST Embeddings Hybrid Retrieval Claude API Evaluation


A multilingual classification system for 100K+ records, combining learned embeddings with rule-based logic and human feedback.

Built with Triplet Loss + Hard Negative Mining and a human-in-the-loop retraining workflow, achieving 95%+ classification accuracy.

PyTorch Embeddings Triplet Loss Hard Negative Mining Human-in-the-loop


A real-time voice AI system for detecting and responding to suspicious calls.

Whisper handles speech-to-text, a lightweight rule-based layer provides low-latency and explainable risk detection, and GPT is used selectively for language generation.

Built end-to-end from backend and telephony integration to frontend and deployment.

Whisper OpenAI API Flask Twilio React GitHub Actions Render


A multilingual entity-resolution system for ~50K global records with inconsistent identifiers and noisy text.

Reduced a naïve ~151M pairwise comparison space to tens of thousands of candidates through:

Blocking → ANN Retrieval → Composite Similarity Scoring

Python ANN Embeddings Entity Resolution Multilingual NLP


An ML decision system that treats commodity purchasing as a sequential decision problem rather than just a forecasting problem.

Experiments with XGBoost, Temporal Fusion Transformer, and DQN to generate Buy / Split / Wait recommendations, exposed through a REST serving layer.

XGBoost TFT DQN Reinforcement Learning Time Series REST API


What I Work With

AI / ML
LLM APIs Tool Calling RAG Embeddings PyTorch scikit-learn Reinforcement Learning Whisper LangChain

Backend / Systems
Python FastAPI Flask Django Spring REST APIs SQL

Frontend
React TypeScript Vue.js

Cloud / Infrastructure
AWS Lambda API Gateway S3 GitHub Actions Render

Enterprise Systems
SAP Ariba BW/SAC CAP HANA


What I Care About

I'm interested in the space between a model that works in a notebook and an AI system that actually works.

That means thinking about more than model accuracy:

retrieval · evaluation · latency · grounding · failure modes · human feedback · system integration · deployment

I like experimenting with new AI techniques, but I'm even more interested in understanding when they work, when they fail, and how to turn them into reliable systems.

Pinned Loading

  1. incident-response-agent incident-response-agent Public

    AI agent for evidence-grounded production incident investigation using tool calling, distributed traces, fault injection, and human-approved remediation.

    Python

  2. bug-ranker bug-ranker Public

    Rank likely buggy functions from stack traces (hybrid retrieval + LLM)

    Python

  3. soybeanoil-predict soybeanoil-predict Public

    AI-driven commodity purchase decisions on SAP: XGBoost/TFT/DQN forecasting served through SAP AI Core and exposed via SAP CAP (HANA CDS + OData) for real-time procurement recommendations.

    Python

  4. material-category-mapping-ai material-category-mapping-ai Public

    Multilingual material category mapping system for procurement data using rules, embeddings, and model-based classification.

    Python

  5. phishing-detection phishing-detection Public

    AI voice-based phishing detection system with real-time scam pattern analysis.

    Python

  6. vendor-deduplication-ai vendor-deduplication-ai Public

    Multilingual supplier deduplication and merge pipeline using blocking, fuzzy matching, and embeddings

    Python