SK Telecom has unveiled 'A.X K1', Korea's first large-scale AI model featuring 519 billion parameters ($5.19 \times 10^{11}$). This model represents a significant leap for South Korea in the global AI competition, positioning it alongside leading AI nations.

The core methodology of A.X K1 involves a colossal total parameter count, but for inference, it selectively activates approximately 33 billion parameters ($3.3 \times 10^{10}$). This selective activation mechanism is a key design choice aimed at optimizing operational efficiency, allowing the model to function with lighter specifications when needed, despite its massive scale. This suggests an architecture similar to a Mixture-of-Experts (MoE) model, where different 'experts' (subsets of parameters) are selectively engaged based on the input, balancing computational cost with the benefits of a large model capacity.

A.X K1 exhibits enhanced capabilities compared to smaller and medium-sized models (sub-500B class), demonstrating improved stability in complex mathematical reasoning and advanced multilingual comprehension (with a strong emphasis on Korean). These foundational capabilities enable powerful extensions such as high-level coding assistance and advanced agentic operations. Agentic capabilities refer to the AI model's ability to autonomously understand user intent, make judgments, and execute tasks without explicit, step-by-step instructions. This includes actions like composing emails, generating documents, and proactively seeking clarifying information from users to achieve optimal results.

Crucially, A.X K1 is designed to function as a "Teacher Model" for smaller AI models (those below 70 billion parameters). It serves as a digital public infrastructure, supplying knowledge to and bolstering the entire AI ecosystem, thereby enabling the development of diverse smaller and specialized models. Unlike many global AI models primarily trained on English data, A.X K1 was specifically designed and trained on Korean data from inception, ensuring natural understanding of Korean inputs and making it highly suitable for developing services tailored to Korean culture, economy, and history.

SK Telecom plans to broadly disseminate A.X K1 through its 'A. (A-dot)' service, which has over 10 million subscribers, aiming to make AI accessible to all citizens via various interfaces like phone calls, text messages, web, and app-based interactions (B2C). For B2B applications, its uses span enhanced workplace productivity through 'A. Biz', manufacturing AI solutions for process optimization, real-time character dialogue and autonomous behavior in gaming through collaboration with Krafton, and extending AI models to physical action domains such as humanoid robot technology.

The development of A.X K1 was a collaborative effort by the SK Telecom elite team, comprising eight key institutions: SK Telecom, Krafton, 42dot, Rebellions, Riiid, SelectStar, Seoul National University, and KAIST. This consortium established a "full-stack sovereign AI" value chain, encompassing AI semiconductors, AI data centers, AI models, and AI services, all built with proprietary technology. Each participant contributed specialized expertise: Riiid provided precision through expert knowledge search technology, SelectStar ensured reliability with large-scale data construction and validation, Krafton offered scalability via global multimodal R&D experience, 42dot contributed versatility with on-device AI technology, and Rebellions supplied efficiency with domestic NPU technology. This collaborative approach enhances the model's overall robustness and broad applicability. A.X K1 is also expected to serve as a critical testbed for verifying the performance of domestic AI semiconductor advancements, given the massive data and transfer speed requirements for high-performance AI chip validation.

Moving forward, SK Telecom intends to open-source A.X K1 to foster the domestic AI ecosystem. It plans to release APIs and the model through major development communities and SK Telecom services, providing an AI agent development environment for Korean enterprises. Additionally, parts of the training data used for the model's development will be made publicly available on both public and private platforms, further strengthening the overall competitiveness of the Korean AI landscape. This initiative is seen as a pivotal step towards establishing South Korea as a global top-tier AI powerhouse.