Medical Imaging AI Engineer · AI Team Lead

Yong-Gi Hong

"I build medical AI that ships and gets validated in the clinic."

Yong-Gi Hong profile photo

About

4 yr 6 mo Medical AI experience
3+ Shipped products
3 Filed patents
1st-author SCI paper

Medical imaging AI engineer who turns qualitative clinical judgment into quantitative, reproducible pipelines across CT, MRI, PET, X-ray, and EEG, and takes models all the way from research to product release and clinical validation. I design and implement full pipelines — segmentation, registration, reconstruction, detection, and GAN-based synthesis — and have scaled them into production systems with end-to-end automated testing, multi-GPU batching, and Docker/CI-CD serving, growing from an individual contributor into an AI team lead. In medical AI since 2022 · 3+ shipped products · 4 papers (incl. 1st-author SCI) · 3 filed patents · 2 registered copyrights.

Highlights
  • Lung-cancer RECIST auto-assessment at 91% accuracy (lesion Dice 82%, validated at Asan Medical Center)
  • PET reconstruction model 257× lighter (SSIM 0.983)
  • Posture-dependent lobar volume change quantified at +90.2 mL (LLL)

Core Skills

Modalities

  • CT
  • MRI
  • PET
  • X-ray
  • EEG
  • Cephalogram

AI Tasks

  • Segmentation
  • Registration
  • Reconstruction
  • Detection
  • Classification
  • Image Synthesis (GAN)

Models

  • nnUNet (v2, 2D/3D)
  • SwinUNETR
  • U-Net
  • VoxelMorph
  • CycleMorph
  • Inception-ResNet
  • CycleGAN
  • DP-GAN
  • BMD-GAN
  • OASIS
  • MONAI
  • Hugging Face
  • LLM · RAG

Image Processing

  • DICOM/NIfTI
  • HU clipping
  • Patch/Sliding-Window
  • Rigid/Affine registration
  • VTK (marching cubes)
  • Radon/Sinogram

Languages & Serving

  • Python (primary)
  • C
  • FastAPI
  • Django
  • Docker
  • CUDA
  • GitOps CI/CD
  • GitHub Actions
  • AWS · GCP
  • SQL
  • model compression

Collaboration

  • Gradio
  • Streamlit
  • Git/GitHub/GitLab
  • Notion
  • Jira
  • Figma
  • Slack
  • Weights & Biases
  • Redmine

Work Experience

From the lab in 2018 to now — across the full medical-imaging spectrum: cardiac CT, chest CT, X-ray, PET, and EEG.

Sep 2025 — Present

AI Team Lead

DivineTech · cardiosim-ai

Design and development of cardiosim-ai, an automated TAVR planning pipeline from cardiac CT; team lead.

  • Designed a 3-model nnUNetv2 cascade: 23-class whole-heart segmentation → Aorta/LV/Coronary sub-segmentation → 9-point landmark detection from a 2-channel CT+mask input
  • Recovered missing landmarks via probability maps (center-of-mass/argmax); aligned IJK/RAS/VTK coordinate systems; generated STL meshes with VTK marching cubes
  • Modeled a 3-leaflet valve from 3 commissure points; auto-extracted calcification by HU thresholding; fit centerline to auto-measure TAVR metrics
  • Polling-worker + REST architecture, GPU lazy load/release, 2-GPU parallel batching, stage-level fault tolerance with E2E tests, Docker/GitOps CI-CD
nnUNetv2 PyTorch/CUDA VTK SimpleITK Docker/GitOps
May 2023 — Aug 2025

R&D AI Researcher

Tesser · AIRECIST

Owned the full AIRECIST pipeline for automated lung-cancer RECIST response assessment.

  • Reframed a reproducibility problem (inter-reader RECIST agreement below 70%) into four stages: lesion segmentation → pre/post registration → tumor tracking → automated RECIST decision
  • Combined nnUNet-based segmentation with ROI preprocessing (DICOM→NIfTI, lung-window HU clipping); implemented VoxelMorph-based registration and a custom tumor-tracking algorithm
  • Result: lesion Dice 82%, RECIST auto-decision 91% accuracy, clinically validated at Asan Medical Center (Dept. of Radiology)
  • Ontol for Clinics (AI health-checkup reports): contributed the algorithm that drafts physician findings from checkup values in the EMR database
  • TIPS project (breast-cancer report analysis & personalized MRI 3D visualization): NLP report summarization, plain-language medical term rewriting, and tumor / lymph-node / body segmentation on breast MRI
  • Contributed to a MOTIE national R&D project (cardiovascular biomechanics digital simulator)
CT Lung Segmentation Registration RECIST
Mar 2022 — Apr 2023

R&D AI Researcher

MedicalIP

Developed and productized commercial segmentation, GAN, and registration models.

  • DeepCATCH (commercial): whole-body CT multi-organ segmentation with 30+ classes using 2D/3D nnUNet, SwinUNETR, U-Net — consistent quality across large multi-center data
  • TiSepX (commercial): X-ray tissue separation GAN (bone/lung/pulmonary) — benchmarked CycleGAN, DP-GAN, BMD-GAN, OASIS; model compression for fracture detection and DEXA BMD use
  • Synthesized X-ray images from CT volumes (DRR-based) to expand the training set
  • Lung / Multi-phase Registration (registered patent, co-inventor): Lung Seg → Affine → DL registration (VoxelMorph-based cascade), patch training with sliding-window inference
  • Result: quantified prone-posture lobar volume gain of +90.2 mL (LLL) / +52.5 mL (RLL), established an LLL volume–FVC correlation
nnUNet SwinUNETR VoxelMorph CycleGAN family
Jul 2018 — Feb 2022

Undergraduate / Graduate Researcher

Gachon University, MMMIL Lab · Advisor: Prof. Haeng-Geun Kim

Multi-modality medical imaging research.

  • EEG breathing-pattern classification with LDA/Random Forest → 1st-author SCI paper (Brain Sciences, 2021)
  • AI-Dentis (malocclusion & cephalogram): Inception-ResNet classifier with Grad-CAM → novel first-molar relative-distance classification (master's thesis, patent, web commercialization); 46-landmark cephalogram detection and a labeling tool
  • PET reconstruction (SITL): physics-informed lightweight model — 247K parameters (vs. DeepPET's 63.6M → 257× lighter), SSIM 0.983 / PSNR 36.6 dB, validated with a self-fabricated PET phantom
EEG Inception-ResNet PET Reconstruction

Education

Mar 2020 — Feb 2022

M.Eng., Biomedical Engineering

Gachon University · GPA 4.38/4.5 · MMMIL Lab

M.S. Thesis: Deep-learning malocclusion classification using pseudo relative distance between first molars (2022)

Mar 2014 — Feb 2020

B.Eng., Biomedical Engineering

Gachon University

Military service (2015–2017)

Selected Projects

Selected GitHub projects. Full list at github.com/HongYongGi.

Patents & Copyrights

Filed patents and registered software copyrights.

Patent filed

Ensemble-based malocclusion classification method & application

Related to AI-Dentis

10-2022-0065182
Patent filed

Medical image registration method and apparatus

Principal inventor · related to Lung Registration

10-2022-0132732
Patent filed

Same-lesion tracking method and apparatus using medical images

Related to AIRECIST

Filed
Copyright

Malocclusion classification web

Copyright held by Gachon Univ. Industry-Academic Cooperation Foundation (work for hire) · contributor · commercialized at Dentis

C-2020-041029-2
Copyright

Cephalogram X-ray labeling tool

Copyright held by Gachon Univ. Industry-Academic Cooperation Foundation (work for hire) · contributor · commercialized at Dentis

C-2021-033245

Publications

Published and in-progress research.

2021 · SCI · 1st author

Identification of Breathing Patterns through EEG Signal Analysis Using Machine Learning

Hong, Yong-Gi et al., Brain Sciences 11(3):293, 2021
2022 · M.S. Thesis

Deep-learning malocclusion classification using pseudo relative distance between first molars

Y.-G. Hong, Gachon Univ.
Poster presentation · PET reconstruction

"Image Reconstruction Network with Sinogram-to-Image Transform Layer for Projection Data"

In progress · Lung quantitative analysis

"Deep-learning segmentation & registration-driven lung parenchymal volume/movement CT analysis in prone positioning."

Certifications & Awards

Awards and certifications held.

Award Dec 2025

2025 SeSAC Hackathon Offline Finals — 2nd Place (2 of 32 teams) · Seoul Mayor's Award

Hosted by DACON. Team NEST Lab — insect ecology & risk platform: YOLOv8 detection + hierarchical classification + risk assessment web service

Certification Jul 2026

Ansys Certified Expert / Fluids Channel-Partner Certifications ×4

Issued by Synopsys

National certificates

Craftsman, Information Equipment Operation · Craftsman, Information Processing

Human Resources Development Service of Korea · ITPLUS Level 2

Funded projects

Government-funded projects

TIPS project (breast-cancer report analysis & personalized MRI 3D visualization) · AI Voucher program · Data Voucher program · MOTIE cardiovascular biomechanics digital simulator