Hi Ajay,
Please check the following thread that discuss a similar question:
Use of UJ VALIDATION and BAdI UJ_VALIDATION_RULE_LOGIC
You may also have a look at the following documents that bring information and examples on how to implement UJ_VALIDATION:
How to do Breakdown Validation in SAP BPC 7.0 for the SAP NetWeaver Platform
How to implement a Master Data Validation in BPC NW - Enterprise Performance Management - SCN Wiki
Best regards,
Francielle