A short-selling net balance becomes reportable when it clears both 0.01% of shares outstanding and 100 million won in value, or 1 billion won on its own. Market caps of 1 trillion and 10 trillion won are where those two tests swap places.
Neither Korea's market stabilization fund nor a full short-selling ban has an automatic trigger. Counting the four past bans, 20.9% of the days since October 2008 were spent under one.
Korea discloses short positions from 0.01% of shares outstanding. Here is where to find the KRX data, why it lags two business days, and how it differs from the stock lending balance.