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Umut Derebek
All projects

SICPA Turkey · 2023 – present

Corporate AI Chatbot

Multi-agent RAG & LLM fine-tuning pipeline

A fully local, department-isolated corporate assistant built on a multi-agent Retrieval-Augmented Generation architecture with self-hosted LLMs.

Illustrative visual — not a real screenshot; sample data is shown.
Role
Fullstack Developer
Period
2023 – present
Context
SICPA Turkey
Status
In production

Highlights

  • 01

    Built an advanced RAG pipeline: Qdrant vector store with department-isolated collections, hybrid dense + BM25 search, cross-encoder reranking, HyDE and multi-query expansion, semantic/parent-child chunking and a hallucination checker; bilingual embeddings (nomic-embed-text for English, multilingual-e5-large for Turkish).

  • 02

    Designed a multi-agent orchestration layer (LangChain + LangGraph) with a supervisor routing queries to specialized agents (HR, tech, market, fact-checker, self-critique, translation, summarization) including prompt-injection / PII guards.

  • 03

    Served local models with Ollama (Qwen, gpt-oss, llama3.2-vision) behind a multi-provider abstraction with OpenAI / Anthropic / Azure fallback, streaming responses, token-budget context fitting and Prometheus metrics.

  • 04

    Designed a feedback-driven DPO (Direct Preference Optimization) fine-tuning pipeline: mined high- vs low-rated production responses into prompt/chosen/rejected preference pairs and customized models via Ollama Modelfiles.

  • 05

    Built a separate Turkish subtitle/transcription pipeline with Whisper (whisper.cpp, large-v3-turbo) and a rule-based SRT cleaning engine (~60 Turkish correction rules) producing final SRT/ASS subtitles and DOCX transcripts.

Architecture

  1. 01

    Ingest

    Semantic / parent-child chunking, TR + EN embeddings

  2. 02

    Qdrant

    Department-isolated collections

  3. 03

    Hybrid retrieval

    Dense + BM25, HyDE, cross-encoder reranking

  4. 04

    LangGraph supervisor

    Routes to specialist agents; PII / injection guards

  5. 05

    Ollama

    Local models, OpenAI / Anthropic / Azure fallback, streaming

  6. 06

    DPO loop

    Rated answers → preference pairs → Modelfile

Other projects

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SICPA Turkey · 2023 – present

RTU-MYS / MzTurnCounter

Museum visitor counting & device monitoring

Visitor-counting and remote-device-monitoring platform for Turkey's Ministry of Culture & Tourism, ingesting turnstile telemetry from a fleet of Raspberry Pi RTUs (Remote Terminal Units).

  • C# / .NET 8
  • ASP.NET Core MVC
  • EF Core
  • PostgreSQL (AWS RDS)
  • Python

SICPA Turkey · 2023 – present

Exprova

Corporate expense management platform

Mobile + web platform for capturing, submitting and approving employee expense reports and cash advances, with SAP accounting-code integration.

  • Laravel 10
  • PHP 8.1
  • MySQL 8
  • Laravel Sanctum
  • RabbitMQ