Besides the main objectives, there are other objectives as follows:~[Phase I]~To assess the pharmacokinetic profile of HM781-36B(Poziotinib) combined with Paclitaxel and Trastuzumab~To evaluate anticancer activity of HM781-36B(Poziotinib) combined with Paclitaxel and Trastuzumab in patients with HER-2 positive advanced gastric cancer~To evaluate PFS(Progression-Free Survival), TTP (Time To Tumor Progression), and DOR (Duration of Overall Response)~[Phase II]~To assess the safety, tolerability of HM781-36B(Poziotinib) combined with Paclitaxel and Trastuzumab~To evaluate tumor response through determination of disease control rate , PFS(Progression-Free Survival), TTP (Time To Tumor Progression), and DOR (Duration of Overall Response)
[Phase I] The main objective of this study is to evaluate the safety, tolerability and determine the Recommended Dose (RD) of HM781-36B(Poziotinib)combined with Paclitaxel and Trastuzumab~[Phase II] The main objective of this study is to evaluate anticancer activity through determination of response rate of HM781-36B(Poziotinib)combined with Paclitaxel and Trastuzumab in patients with HER-2 positive advanced gastric cancer