function freezeCheck(address _from, uint256 _value)  returns (bool) {
  	if (block.timestamp < unfreeze_start_date) {
  		require(balances[_from].sub(frozenAccount[_from]) >= _value );
  	} else if(block.timestamp < unfreeze_end_date) {
      require(balances[_from].sub((frozenAccount[_from] / unfreeze_periods) * ((unfreeze_end_date -  block.timestamp) / unfreeze_period_time)) >= _value);
  	}
    return true;
  }