OpenAI held its first Dev Day in Seoul on the 13th, unveiled the GPT-5.1 series, and began a full-fledged push into Korea's B2B market. The event was attended by about 150 domestic ICT officials and served as a venue to introduce key technologies announced at the U.S. Dev Day directly to Korean corporations.
It was the first time OpenAI hosted its developer event, Dev Day, in Seoul, organized as part of its domestic business expansion following the establishment of its third Asian branch after Japan and Singapore on Sept. The company said it plans to use this event as a starting point to strengthen networking with domestic corporations and accelerate the expansion of partnerships.
The GPT-5.1 Instant and GPT-5.1 Thinking models unveiled that day are said to have significantly improved reasoning capabilities and more natural responses compared with the previous generation. The Instant model features adaptive reasoning that determines on its own whether reasoning is necessary depending on question difficulty, while the Thinking model finely adjusts thinking time based on problem complexity to provide deeper analysis. Another feature is reduced use of technical jargon to improve comprehension.
In addition, the range of tone and style choices for ChatGPT has been expanded. In addition to the existing basic, friendly, and efficient options, three new styles—professional, direct, and quirky—have been added.