Seoul is exactly 1 hour ahead of Singapore year-round. When it's 3:00 PM in Seoul, it's 2:00 PM in Singapore. Neither South Korea nor Singapore observes daylight saving time, so this difference is constant.
The minimal time difference makes business coordination between these two Asian financial hubs extremely convenient.
Any business hours work great! With only a 1-hour difference, 9:00 AM - 6:00 PM Seoul corresponds to 8:00 AM - 5:00 PM Singapore. Full business day overlap.
Korean conglomerates have significant operations in Singapore, and K-pop and Korean entertainment have a massive fanbase in Singapore. Direct flights connect the cities in about 6 hours.