Importing Personal Items and Electronics: how it works in South Korea — first-hand
Short answer
Travelers can bring multiple phones, cosmetics, and books for personal use or as gifts without strict quantity limits. As long as these items are not intended for commercial resale, they typically pass through customs without issues.
From real experience
Regarding the number of mobile phones one can bring into South Korea, there isn't a strict limit explicitly stated for personal use.
However, bringing an excessive number of devices, especially if intended for resale, could raise questions at customs. Typically, travelers bring their personal phone(s) and perhaps a couple of additional devices for gifts or other purposes without issue. If traveling with multiple phones (e.g., two personal and two for gifts), it's generally permissible as long as they are for personal use or intended as gifts and not for commercial resale.
✓ 2 reports from chats
Bringing cosmetics and clothing from South Korea to Russia for personal use typically does not raise concerns at customs, even with significant quantities.
Travelers have reported successfully bringing large amounts of cosmetics or multiple large suitcases (up to 23 kg each) without facing customs inquiries or issues. The assumption is that these items are for personal consumption rather than commercial resale.
✓ 1 report from chats
Transporting books, particularly a significant quantity of literature, as checked baggage when entering South Korea is generally permissible.
Customs authorities typically do not impose restrictions on personal literature, allowing travelers to bring their books without issue.