Answer:
The presence of parliament does not necessarily imply that a given country has a parliamentary democracy. In a presidential democracy, legislative branch of power is represented by the parliament and headed by the prime minister, while the executive branch is represented by the President. The key point that makes a democracy presidential is the fact the President is elected is and is not being responsible to the Parliament.
In South Korea the president is the highest authority in the country and is elected directly by people every five years. He is followed by the Prime Minister in the power of authority.