Hospital Core Platform & Automatic Reception
Core reception and reservation flows for hospital products, including reservation API reliability, patient visit logic, and customer-specific data boundaries.- Designed and maintained reception logic from patient visit through clinical workflow handoff.
- Hardened reservation API paths through Slack webhook cleanup, taxable/non-taxable fields, query optimization, slow web-reservation POST/PATCH fixes, reservation-count sync locking, reservation-log trigger cleanup, and CRM list polling optimization.
KotlinSpring BootGraphQLSQL ServerPostgreSQLRedis
Kubernetes Platform Modernization
Helped move a legacy cloud platform toward service-oriented architecture, Kubernetes-based deployment, and measurable production observability.- Supported Elastic Beanstalk to EKS migration work with Terraform, Helm, ArgoCD, Rancher, and Kubernetes operations.
- Advanced monitoring through Prometheus, Grafana, Jaeger, Datadog, CloudWatch logs, and KPI dashboards.
EKSTerraformHelmArgoCDIstioPrometheus
ML-Trade: Intraday Futures Research Pipeline
Research-first quant pipeline for MES/ES intraday opportunity selection, turning Databento OHLCV and MBP feeds into clean features, labels, deterministic baselines, and model-ready validation gates.- Built the market-data path from raw Databento files into bronze/silver Parquet datasets, strict training matrices, chronological splits, manifests, and reproducible research reports.
- Designed the research gate around feature information-coefficient reports, strategy-family benchmarks, horizon and roll-rule sensitivity, lookahead audits, MBP microstructure diagnostics, latency/fill/cost stress, and candidate failure attribution.
PythonXGBoostRandom Forestscikit-learnFeature EngineeringParquet
Borg Agent Orchestrator: Kubernetes Remediation Research
Research system that turns Borg-inspired workload traces and live Kubernetes telemetry into risk and demand predictors, multi-agent remediation decisions, and dual-cluster comparison evidence.- Built the six-layer path from Prometheus/JSON ingestion and simulator feature extraction to XGBoost risk/demand models, RLlib PPO policy evaluation, Optuna reward tuning, and scoreboard feedback.
- Validated the control loop on local Kind clusters with AIOpsLab-style incidents, Prometheus/node-exporter telemetry, HPA/local-Karpenter baselines, live Kubernetes action execution, and repeated-seed policy gates.
PythonXGBoostscikit-learnRay RLlibOptunaPolarsKubernetesPrometheus
Trade-Area Analysis & Property Recommendations
Near-startup proptech product that helps founders evaluate Seoul trade areas and shortlist commercial property listings through score-driven analysis, map workflows, and recommendation APIs.- Built backend and frontend surfaces for map-based trade-area analysis, property search, Top 3 recommendations, saved analyses, and detailed listing inspection.
- Implemented API flows around analysis creation, polling and SSE progress, property filtering, structured prompt search, horizon survival scores, score explanations, and metric references.
KotlinSpring BootReactTypeScriptPostgreSQL
Semo: Travel Companion & Trip Networking
Award-winning travel mobile product that connects travelers and locals through trip cards, city-based place discovery, nearby mingles, quick matches, saved places, and translated chat.- Built Kotlin Spring Boot APIs for trips, city and nationality lookup, restaurants, cafes, saved places, mingles, quick matches, chat rooms, and profile image upload.
- Implemented React Native screens and service integration across Home, Nearby, QuickMatch, Chats, trip history, saved places, profile, and trip creation flows.
KotlinSpring BootReact NativeWebSocket/STOMPOpenAI
Smart Chart & Medical API Migration
Migrated chart, prescription, diagnosis, billing, and medical business logic from a large legacy C# engine into maintainable Kotlin Spring Boot APIs.- Refactored high-risk medical workflows with clean code, clearer API boundaries, and production comparison tooling.
- Built backoffice checks to compare old engine SQL output with new API behavior before rollout.
KotlinSpring BootHibernateOpenAPIC# migration
Clinical Workflow Product Lines
Built and stabilized product lines around kiosk payment, patient waiting screens, procedure assignment, and doctor-facing operational statistics.- Implemented smart payment flows for kiosk payment, cancellation, refunds, receipts, points, and transaction recovery.
- Stabilized waiting-room TV and tablet updates, including TTS and media-streaming behavior across Kubernetes replicas.
KafkaDebeziumAWS SQSRedisSAGAWebSocket
CashDoc Chat & CRM Realtime Messaging
Production-bound chat platform work for CashDoc and CRM consultation workflows, covering MVP group chat, read states, authentication, and socket stability.- Built the chat-server MVP through group conversation support, read receipts, authentication, and CashDoc user flows.
- Connected realtime CRM socket events with Kafka-backed paths and web-reservation APIs.
Socket.IOWebSocketKafkaOpenAPIDatadog
Hospital KPI & User Flow Dashboards
Turned KPI and user-interaction data into manageable dashboard views so product flows could be tracked and leadership could read the business signal clearly.- Structured hospital product events and user interactions into dashboard-ready views.
- Supported user-flow tracking across key product journeys so drop-offs and operational signals were easier to inspect.
BigQueryPrefectPostgreSQLDatadogDashboards
Korean Learning Platform For Foreign Learners
Built a Korean-learning product through SWMaestro, covering ideation, planning, backend development, deployment, and app launch.- Developed video-processing flows for subtitle-based learning and speaking practice.
- Used NLP and OpenAI APIs to extract vocabulary examples and usage context from learning material.
JavaSpring BootFlaskOpenAInginx
Reliability Tooling & Developer Productivity
Turned recurring operational friction into contract gates, runtime diagnostics, log-noise reduction, and sharper debugging loops for the engineering team.- Investigated Hikari reconnect behavior, DB lock patterns, cache hit paths, slow APIs, and log volume problems.
- Built controller/client contract gates and explored IDE navigation tooling for Feign-to-controller flows.
OpenAPI Contract GatesHikariCP RecoveryDB Lock AnalysisAPM Trace DebuggingDev-Server Sharding