OWL version of Dublin Core?

Hi, This may be a FAQ, but are there OWL versions of
Dublin Core Vocabularies?

I checked their official page[1], but there seem to be no
such versions.

If not, is there any widely-used ontology that refines the
DC Vocabularies in OWL?

Or are there unofficial versions that are in discussion / under review by DC people?

My current problem is that I want a transitive version of 
http://purl.org/dc/terms/isPartOf .

Should I use a property in other major vocabularies, 
for example 
http://www.w3.org/2001/sw/BestPractices/OEP/SimplePartWhole/part.owl#partOf
(I'm not sure if it is major, though)

Or defining my own transitive property as a subPropertyOf 
http://purl.org/dc/terms/isPartOf 
would make more sense?

[1] http://dublincore.org/

Best,
Yoshio Fukushige

-- 
Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>
Network Development Center,
Matsushita Electric Industrial Co., Ltd.