Is it traditional in Korean Tae Kwon Do 8th Dan to be given the title of 'World' Master if the person is established in Aust and NZ?
There is no such thing as a "World Master" rank in any of the official Taekwondo federations that I'm aware of.
However, there is the WTF, the World Taekwondo Federation. A master rank in the WTF might be misinterpreted as "World Master". Maybe that's what you're seeing?
Also, I just did a Google search on the term, and I found out there quite a lot of places that sound similar: "World Taekwondo Masters Union", "World Taekwondo Masters Association", "World Class Taekwondo", etc. The term "World" is used quite a lot with Taekwondo organizations.
ITF Taekwondo has a rank structure that places 1st dan through 6th dan as "instructor" ranks, and 7th dan through 9th dan as "master" ranks. The interesting thing is that its 1st through 3rd dan are called "national instructor" ranks, while its 4th through 6th dan are called "international instructor" ranks. However, a similar "international" rank does not exist in the master ranks. The 7th dan is a "junior master", 8th dan is a "senior master", and 9th dan is a "grand master". The 10th dan is mostly honorary, awarded to only a handful of people, and is referred to as a "supreme grand master".
So, my best guess is that someone got confused and called their 8th dan a "world master" instead of a "senior master". It's a minor issue, because 8th dan is 8th dan no matter what you call it in English.
Hope that helps.
An 8th Dan is a Master(Sahyun-nim). Not a 'World Master'.
However it could be a title within the person's own federation/association in Aust and NZ (and many other parts of the world). He can be a 'World Master', or 'Senior GrandMaster', or 'Supreme Grandmaster' or 'Senior Master', but traditionally an 8th Dan is called a Master.
A Master title is given to those who have attained 7th Dan and 8th Dan. Upon attaining 9th degree the person is deemed a Grandmaster. No more ranks above 9th Dan, although there are federations going beyond that.