Although Pepsi Logo and Korean flag look similar nowadays, but they are originated differently, and by tracing the chronology, we can see they are originated from different concept:

Here is the Pepsi logo chronology:
http://www.logoblog.org/pepsi_logo.php

Here is South Korean flag chronology:
http://www.worldstatesmen.org/Korea_South.htm
(note the dramatic flag changes during the world war period (1910~1945) because Korea was conquered by Japan at that time)

As we can see, Pepsi’s original logo design include a wave-like pattern and adapts 3 colors (red, white and blue) with letters in the middle. And the symbol later on being simplified by taking out the letters.

On the other hand, Korean flag is based on the simplified concept of Taichi and Bagua from ancient Chinese culture. And the white color is not an element in the flag center.

Source: WikiAnswers.com

:D So next time would you think of South Korea when you drink Pepsi?

New Pepsi commercial featuring Super Junior-M, Show Luo, Lee Jun Ki, Louis Koo, Jolin Tsai and Huang Xiao Ming