Projects

A selected set of projects I’ve led over the years. Most are work done under NDA, so descriptions stay at a high level.

CoupangGPT-VL — Vision-Language E-commerce Model

2024 — present · Coupang · Team Lead

A unified vision-language foundation model for e-commerce. I initiated and led the multimodal redesign of Coupang’s search experience: queries and product metadata (titles, images, descriptions, OCR text) are encoded into a shared embedding space for multimodal retrieval.

• Built a multi-turn conversational ShopBot powered by CoupangGPT-VL for natural-language product discovery.
• Improved click-through rate (CTR) by 13.4% on the redesigned search surface.
• Enabled better semantic retrieval on hard queries (“breathable shoe cabinet” → items with ventilation and airflow attributes).
• Introduced grounded summaries that explain why a product was recommended.

CoupangGPT — Scalable E-commerce Language Model

2023 — 2025 · Coupang · Team Lead

Led end-to-end development of CoupangGPT, a multimodal reasoning GPT pretrained on 1.5 trillion tokens, images, and proprietary e-commerce data — powered by GRPO reinforcement learning and multimodal instruction tuning. Used across search relevance, search ranking, catalog, and ads quality.

• Managed a team of 5 ML engineers, a data scientist, and several product analysts.
• Partnered with infra to stand up Coupang’s first multinode training cluster — 1000+ A100 / H100 / H200 GPUs on p4 / p5 / p5en instances with EFA and InfiniBand.
• Delivered weekly progress updates to VP and Director-level stakeholders.
• Pretraining / post-training stack: PyTorch, FSDP, DeepSpeed, GRPO, DPO.

Search Relevance with CoupangGPT

2023 — 2025 · Coupang · Team Lead

Reformulated search relevance as an instruction fine-tuning problem — does this (query, product title, metadata) tuple constitute an exact match? Drove EM accuracy from 0.55 → 0.99 through iterative distillation from larger teacher models.

Coordinated 100+ human annotators with PMs to nail down labeling guidelines. The EM lift translated into a measurable lift in purchase rate.

Query Understanding with CoupangGPT

2024 — 2025 · Coupang · Team Lead

A multi-task query understanding pipeline — spelling correction, brand detection, query category prediction, query expansion — trained without any human labels for the bootstrap round.

• Used Gemini-3-Pro via advanced prompt engineering to generate zero-human-label training data.
• Scaled via knowledge distillation: Gemini-3-Pro → CoupangGPT student.
• The distilled student matched or surpassed the teacher on internal evals.
• Shipped a 2–3% lift in PPC (purchases per customer).

OGPT — On-Device Chatbot for OPPO Smartphones

2021 — 2023 · OPPO · Tech Lead

A high-performance chatbot deployed on smartphones, serving 10M+ monthly users.

• Applied DPO for instruction-following alignment.
• Distributed training across multiple nodes with FSDP, Lightning, DeepSpeed.
• Integrated multiple LLMs with LangChain; advanced prompt engineering to extend utility across use cases.

Semantic Search for OPPO Photo Album

2021 — 2023 · OPPO

Replaced keyword matching on the smartphone Photo Album with a vision-language semantic search stack. Contrastive pretraining of text-image pairs, transformer-based query encoding, and nearest-neighbor retrieval delivered a 10% F1 improvement over the previous system.

Fashion Captioning & FACAD

2019 — 2020 · Stony Brook · PhD research

Released the FACAD dataset and a reinforcement-learning-with-semantic-rewards method for generating accurate fashion captions, published at ECCV 2020.

• GitHub — xuewyang/Fashion_Captioning
• Benchmark repo

Open Source

2024 — present

Active contributor to Axolotl and ms-swift — scalable post-training, instruction tuning, and RL training pipelines.