Data Scientist · Applied AI Scientist · Ph.D. Statistics

Turning ambiguous business problems into production decision systems.

I lead applied AI at a group holding company's AI center, across manufacturing, logistics, bio/healthcare, retail and media. LLM/RAG and agentic systems, mathematical optimization, causal inference and forecasting — owned end to end, from problem definition to deployment and validation.

Seoul, Korea7 patents · 8 publicationsTechnical lead, CJ AI Center
7patents (lead or named inventor)
$1.86Mconfirmed bio-process cost savings
+20%logistics productivity, field-validated
95%recall, ad legal-risk review in production
8peer-reviewed papers & posters
Featured work

Systems that run in real operations

Three recent builds at CJ AI Center, each patented and in production. Every one started as a problem nobody had framed yet.

GenAI · Regulated domain · Patent (lead inventor)

Advertising copy legal-risk review AI

OCR with coordinate grounding, RAG over an 11,000-item per-category violation knowledge store, an independent verification unit and retrain-free policy evolution. Flags risky copy with its judgment basis and on-screen location.

Precision 81% · Recall 95%499 ad imagesIn production
Multi-agent LLM · Self-hosted · Patent

Group-wide HR recruitment assistant

Parallel summarization, evidence-highlighting and interview-question agents with an independent self-correcting verification layer. Core models internalized on an open GPT-OSS base; ~73,000 applications across three cycles.

QA-FactEval 83.5% vs 76.0% commercialReview time −50%Production 2026
Causal discovery · Simulation · 5 patents

Bio-process optimization across three global plants

Causal discovery and inference over fragmented process data to find actionable operating conditions, plus an in-silico simulator process experts use to test hypotheses before touching the line. Some conditions became plant standards.

≈ USD 1.86M confirmed savings3 sitesTechnology licensing
Capabilities

Four ways I turn a question into a system

Methodological depth from a statistics Ph.D., applied by hand: each capability below is listed with the production or research work it was used in.

LLM/RAG & agentic systems

LangGraph workflows, hybrid search and re-ranking, verification agents, prompt and context engineering, self-hosted model internalization, FM evaluation.

  • Dr. SmileGut — commercial RAG advisor, launched 2025-04
  • Ad legal-risk review (OCR + RAG)
  • HR multi-agent assistant
  • LLM Floor Supervisor for logistics QPS

Optimization, simulation & decision systems

MILP, metaheuristics, reinforcement learning, discrete-event simulation, routing, bottleneck and inventory models, constraint modeling.

  • Logistics QPS allocation and injection order — +20% productivity
  • Cart-picking system optimization — ≈20% in simulation
  • Cinema scheduling — 30+ business rules as MILP
  • Inventory policy feasibility (MILP / RL / search)

Forecasting & causal inference

TFT, PatchTST, DeepAR, Prophet, tree ensembles; causal discovery (PC, PCMCI, Bayesian networks), PSM/IPTW/G-formula, A/B platforms, survival models.

  • Store demand forecasting for 300+ stores — +5.7% revenue
  • Daily sales forecasting — 97.6% accuracy, early-warning signals
  • Churn causal drivers from ~400 variables
  • CLV with TFT + survival analysis

Bio/healthcare AI & synthetic data

Protein embeddings (ESM2, gLM), structure and clustering tools, microbiome modeling, biostatistics; GAN/diffusion/copula synthetic data with privacy-utility evaluation.

  • 100M+ protein sequences → ~6M clusters, 60× faster embedding
  • Immunotherapy response +15% over ML baseline — SITC 2024
  • Certified anonymized telecom data via the KISA program
  • Clinical-trial statistics and Bayesian dose finding
Live demos

The core models, rebuilt on synthetic data

Each demo re-implements the decision logic of a project and lets you change the data and watch the model work. No company data, identifiers or layouts are used; demo pages are in Korean.

Selected work

Experience, project by project

CJ AI Center

2023 — present · Data Scientist / Applied AI Scientist, Technical Lead

The group holding company's central AI organization, taking on cross-affiliate problems that individual companies cannot solve alone. I set technical direction, review architectures, mentor data scientists and work directly with affiliate executives and domain experts.

GenAI · Production

Dr. SmileGut personal AI advisor

Vector DB, LangGraph workflow, hybrid search and re-ranking, guardrails for a microbiome-health advisor.

Commercial launch 2025-04-09
Agentic · Deployed

Logistics QPS real-time decision agent →

Workload allocation, task priority and bottleneck response, plus an LLM-agent AI Floor Supervisor in operation; multi-center rollout.

+20% productivityfield-validated
Bio AI · Research

Immunotherapy response prediction & biomarker discovery

ESM2/gLM embeddings, AlphaFold/ESMFold, MMseqs2/Foldseek clustering; vector search over ~6M sequences in 1–2 s.

+15% over ML baselineSITC 2024 poster
Optimization

Cart picking system optimization →

Order-box mapping, cart allocation, routing and bottleneck waiting reformulated as one problem, with standardized inputs for multi-center rollout.

≈20% productivityin simulation
MILP · Forecasting

Cinema scheduling optimization

30+ scheduling rules as MILP constraints with tractability work; occupancy prediction by site and time slot.

≈10% MAEoccupancy model
Forecasting · Licensed

Store demand forecasting & production recommendation

Re-scoped a seasonal forecast into year-round store/category forecasting for 300+ stores (TFT, PatchTST, DeepAR) with a Streamlit dashboard.

+5.7% revenuetechnology licensing
Forecasting

Predictive management signals

Daily sales forecasting and a traffic-light system that flags monthly-target risk about a month early.

97.6% accuracy
Analytics · LLM

Integrated data analytics & persona analysis

Cross-affiliate data connected with LLM-based persona estimation and an insight dashboard.

Drove platform investment
Feasibility

Inventory optimization

MILP, search, RL and simulation evaluated; demand-based inventory policy proposed.

Capacity & transport savings quantified

LG Uplus

2020 — 2023 · Data Scientist / Technical Lead

Customer retention, customer value, experimentation and synthetic data on telecom-scale data across mobile, IPTV and subscription services.

Synthetic data

Synthetic data generation & public-sector data sharing

WGAN, CTGAN, CTAB-GAN, TabFair GAN, TTS-GAN, TABDDPM, MTcopula; certified anonymized IPTV, delivery-app and mobility data through the KISA program.

External data provision unlocked
Causal inference

Causal drivers of mobile churn

~400 variables; PC, PCMCI, Bayesian networks, PSM, IPTW, G-formula.

Churn-gap vs. leader narrowed
Experimentation

A/B testing platform

Metric definition, sample size, randomization, testing, Bayesian and bandit extensions for IPTV and mobile TV.

Standardized experiments
Customer analytics

CLV, household inference, engagement score, IPTV revenue

TFT + survival CLV; Parallel Louvain household detection; RFM-based engagement; Bass diffusion and Prophet revenue models.

Four analytics foundations

CCNI Research · Hanmi Pharmaceutical

2017 — 2020 · Statistician / Biostatistician

Disease-exacerbation prediction under heavy class imbalance, clinical-trial statistical analysis plans, and early-phase dose-finding methodology (Bayesian logistic regression, CRM, graphical test procedures).

Research & IP

Publications and patents

Associations of the gut microbiome with immune checkpoint inhibitor response across cancer types and cohorts identified using random forest and language modelsSITC 2024, Poster 1265 · Yang, Oh, Lee et al.
Statistical assessment of biosimilarity based on the relative distance between follow-on biologics for time-to-event endpointsStatistics in Biopharmaceutical Research (2020) · Lee & Kang · first-author methodology
Alertness during working hours among eight-hour rotating-shift nurses: an observational studyJournal of Nursing Scholarship 54(4), 2022
Effects of low-dose pirfenidone on survival and lung function decline in patients with IPF: results from a real-world studyPLoS ONE 16(12), 2021
Sleep, fatigue and alertness during working hours among rotating-shift nurses in KoreaJournal of Nursing Management 29(8), 2021
Readmission of high-risk discharged patients at a tertiary hospital in KoreaThe Journal for Healthcare Quality 41(4), 2019
Combined effects of diabetes and low household income on mortality: a 12-year follow-up of 505,677 Korean adultsDiabetic Medicine 35(10), 2018
Diabetes, frequency of exercise, and mortality over 12 years: analysis of the NHIS-HEALS databaseJournal of Korean Medical Science 33(8), 2018
Patents
7
  • 5 — causal condition discovery and bio-process optimization
  • 1 — advertisement copy legality monitoring with OCR and retrieval-augmented generation (lead inventor)
  • 1 — recruitment document reading assistant using evidence-candidate generation and multi-agent verification
Also
  • Technology-licensing agreements (demand forecasting, process optimization)
  • Internal technical documents, RL hands-on workshop, trend reports, LLM reading group
  • Teaching at Yonsei University: R & Python programming, Introduction to Statistics
About

Statistician by training, builder by habit

I hold a Ph.D. in Statistics from Yonsei University, where my dissertation developed biosimilarity assessment methodology for time-to-event endpoints. That training — survival analysis, hypothesis testing, experimental design — is still the backbone of how I evaluate every model I ship.

My core strength is redefining a business problem into an analyzable one: translating implicit domain knowledge, operational constraints and business rules into objective functions, evaluation metrics and production-ready systems. I own projects end to end, from problem definition and data pipelines through deployment and performance validation, and I prefer systems that business teams can keep using without me.

LanguagesKorean (native) · English (conversational; peer-reviewed technical writing)
ToolsPython, R, SQL, SAS, SPSS · LangGraph, vector DBs, Streamlit · MILP solvers, simulation
HonorsBrain Korea 21 Plus research excellence scholarship and fellowship · Korea Weather Big Data Contest, agency president award (2016) · highest honors, Inha University
2023 —
CJ AI CenterData Scientist / Applied AI Scientist, Technical Lead
2020 — 2023
LG UplusData Scientist / Technical Lead
2018 — 2020
CCNI ResearchStatistician
2017 — 2018
Hanmi PharmaceuticalBiostatistician
2015 — 2020
Yonsei UniversityPh.D. in Statistics · GPA 4.2 / 4.3
2008 — 2015
Inha UniversityB.S. Statistics & Financial Engineering · GPA 4.4 / 4.5, highest honors, 7 semesters
Contact

Working on a hard, unframed problem? Let's talk.

thstar.ai@gmail.com

Seoul, Korea · Open to applied AI, optimization and data science leadership roles.