if ur stay is less than 12mths in singapore. u r not required to convert ur license. u still can drive in singapore with ur valid Dubai driving licence with proper english translation. but after 12mth stay, u must compulsory convert.
this is e proof
" If you are a foreigner and hold a foreign driving licence and intend to remain in Singapore for less than twelve months, you are not required to convert your foreign driving licence to a Singapore driving licence. You may drive in Singapore with a valid foreign driving licence. However, if your licence is not in English, in addition to a valid foreign driving licence, you are required to have an International Driving Permit. If an International Driving Permit is not available, an official translation of your driving licence in English is required.
If you are holding an Employment Pass/Dependent Pass/Student Pass/or Work Permit and are likely to reside in Singapore for more than twelve months and you wish to continue to drive in Singapore, then you are required to convert your foreign diving licence to a Singapore driving licence before the end of your twelve months stay. "
quoted from
http://driving-in-singapore.spf.gov.sg/services/Driving_in_Singapore/Information/drivinglicence/conversion.htm[/url]