Samsung SyncMaster 400DX-3 User Manual page 150

Specifications
Horizontal Frequency
The time to scan one line connecting the right edge
to the left edge of the screen horizontally is called the
Horizontal Cycle and the inverse number of the Hor-
izontal Cycle is called the Horizontal Frequency.
Unit: kHz
Vertical Frequency
Like a fluorescent lamp, the screen has to repeat the
same image many times per second to display an
image to the user. The frequency of this repetition is
called the Vertical Frequency or Refresh Rate. Unit:
Hz