In this study, we present the design and development of a Generative AI service, Big Data Assistant (BD Assistant), leveraging generative AI to optimize marketing strategies for Samsung Electronics. By integrating customer data of Demographics, device ownership, behavior, and preferences, our AI-driven system automatically extracts customer segments for targeted campaigns in real-time. This approach employs advanced machine learning techniques, including Large Language Models (LLM) and explainable AI, to ensure precise and interpretable segmentation results. Through comprehensive analysis and validation, our system demonstrates significant improvements in campaign effectiveness and customer engagement, paving the way for data-driven marketing strategies that adapt to evolving consumer behaviors. The findings highlight the potential of AI in revolutionizing target marketing systems, offering a scalable solution for personalized and dynamic marketing strategies.