specifying Dublin core and qualifiers in RDF

Hi,
Here at Gem we have been trying to come up with proper RDF, but been running into difficulties with our sub-elements. Were based on the Dublin Core, with additional sub-elements. Could any of you RDF gurus take a look at it? The Dublin core qualifer examples in the RDF speficication didn't seem usable for this work, but tell me if Im wrong! 

We have an odd case with the gem:location, which would fit in to the <dc:Relation> about= tag. How could we retain our element, gem:location, but have it contained within the <dc:Relation> description about= attribute?

Also, what is the best way to specify controlled vocabulary?
Thanks for any comments, I have read the specification over and over without any moments of true inspiration.
Cheers,
Ryan
<?xml version="1.0"?> 
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
xmlns:dc="http://purl.org/dc/elements/1.0/" 
xmlns:gem="http://gem.syr.edu/elements/" 
xmlns:g="http://purl.org/dc/elements/"> 

<rdf:Description about="location"> 
<gem:location>http://www.foo.org</gem:location> 
</rdf:Description> 

<rdf:Description about="http://www.w3.org/RDF/Implementations/SiRPAC/"> 
<dc:Creator> 
<rdf:Description about="http://www.foo.org/resource#Creator"> 
<gem:email>mrain@foo.org</gem:email> 
<gem:postal>123 Foo Dr., Foo AK 99195</gem:postal> 
<gem:phone>707-747-8774</gem:phone> 
<gem:fax>707-747-8774</gem:fax> 
<gem:role>illustrator</gem:role> 
<gem:homePage 
rdf:resource="http://www.foo.org/mrain"/> 
<gem:namePersonal>Mary Rain</gem:namePersonal> 
<gem:affiliation>Foo Organization</gem:affiliation> 
</rdf:Description> 
</dc:Creator> 
<dc:Format> 
<rdf:Description about="http://www.foo.org/#format"> 
<gem:platform>windows nt</gem:platform> 
<gem:contentType 
rdf:resource="http://www.InternetMimeType.org/ControlledVocab"> 
<rdf:value>PowerPoint</rdf:value> 
</gem:contentType> 
<gem:size> 
<rdf:Description about="http://www.foo.org/#size"> 
<rdf:value>50</rdf:value> 
<g:Classification rdf:resource="http://www.nist.gov/units/#Bytes"/> 
</rdf:Description> 
</gem:size> 
</rdf:Description> 
</dc:Format> 
<dc:Relation> 
<rdf:Description about="#location"> 
<gem:publicID>1003-2938</gem:publicID> 
<gem:description>Illustration Agency</gem:description> 
</rdf:Description> 
</dc:Relation> 
</rdf:Description> 
</rdf:RDF