Red color for Below 50% & Green for above 50%
Every minute the threshold percentage changes. For even minute it is 80% and for odd is 40%.
Refresh or auto refreshed after 10s
in Order to dynamically change the color. the Color attribute of the Percent circumferential segment is dependent on item value PX_COLOR.
create Item PX_COLOR and Source ((PL/SQL Function body)

begin
  IF MOD(TO_NUMBER(To_char(sysdate, 'MI')), 2) = 1 then
    return 'RED,GREEN';
  else
    return 'GREEN,RED';
  End if;
end;

In the Circliful plugin => Page Items to Submit => PX_COLOR
In the Circliful plugin => attributes => Set the Following Attributes as following:
Inner Circle Color(s) & Percent circumferential segment color(s) => &PX_COLOR
Percent Text Size: 30,30
Percentage Value From Top(Y);Left(X) (s) : 110,110
Percent Font Color: #FFFFFF,#FFFFFF
Inner Circle Size(s): 45,45
Text Below: Y

Created a Custom DA =>
Custom Event : DAthreshold
Selection Type : JavaScript Expression => document
True Action: Set Value(PL/SQL Function body)

begin
  IF MOD(TO_NUMBER(To_char(sysdate, 'MI')), 2) = 1 then
    return 'RED,GREEN';
  else
    return 'GREEN,RED';
  End if;
end;

Fire on Page Load:Yes
Affected Element: Item(PX_COLOR)
True Action:Refresh(Region Cricliful plugin)
Page Attributes => Run on Page Load:

setInterval( 'apex.event.trigger(document,"DAthreshold");', 200);