Simple Versiom

1
2
3
4
5
6
set diskName to "YourDiskNameHere"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell

More Complex Version

(If disk is currently mounted then unmount, otherwise reverse the process )

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
set diskName to "YourDiskNameHere"
tell application "Finder"
 if disk diskName exists then
  eject disk diskName
 else
  tell current application
   set deviceLine to (do shell script "diskutil list | grep \"" & diskName & "\" | awk '{ print $NF }' }'")
   if deviceLine = "" then
    display dialog "The disk \"" & diskName & "\" cannot be found." buttons {"OK"} default button 1 with title "Error" with icon caution
   end if
   set foundDisks to paragraphs of deviceLine
   repeat with i from 1 to number of items in foundDisks
    set this_item to item i of foundDisks
    if this_item contains "disk" then
     do shell script "diskutil mountDisk /dev/" & this_item
    end if
   end repeat
  end tell
 end if
end tell

Usage Example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
set diskName to "Physical-1號"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell
set diskName to "Physical-2號"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell
set diskName to "Physical-3號"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell
set diskName to "Physical-4號"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell
set diskName to "Physical-5號"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell
set diskName to "Physical-6號"
tell application "Finder"
	if disk diskName exists then
		eject disk diskName
	end if
end tell

Reference

http://hints.macworld.com/article.php?story=20120211184732735