private void m_cmd_thong_tin_nhan_vien_ItemClick(object sender, ItemClickEventArgs e)
 {
     try
     {
         f450_thong_tin_nhan_vien v_f = new f450_thong_tin_nhan_vien();
         if(IsExistFormName(v_f)) return;
         v_f.MdiParent = this;
         v_f.Show();
     }
     catch(Exception v_e)
     {
         CSystemLog_301.ExceptionHandle(v_e);
     }
 }