Yii file_exists() Checking

if(file_exists("".Yii::getPathOfAlias('webroot')."/images/certificate/".$model->certificate_coc_no"")){
  
   echo CHtml::image(Yii::app()->baseUrl."/images/certificate/".$model->certificate_coc_no,
      $model->name,
      array("width"=>"100px" ,"height"=>"80px", "style"=>"vertical-align:middle; margin-left: auto; margin-right: auto; display: block; float: none;"));
   
  }

OR

if(file_exists("".YiiBase::getPathOfAlias('webroot')."/images/certificate/".$model->certificate_coc_no"")){
  
   echo CHtml::image(Yii::app()->baseUrl."/images/certificate/".$model->certificate_coc_no,
      $model->name,
      array("width"=>"100px" ,"height"=>"80px", "style"=>"vertical-align:middle; margin-left: auto; margin-right: auto; display: block; float: none;"));
   
  }