Participants who meet criteria of enrollment and is willing to join in this study will wear a real-time upper gastrointestinal monitoring system for checking whether upper gastrointestinal rebleeding occurs continuously for 3 days.

Participants will wear a monitoring system consisting of a tiny endoscopy and a mobile device. The endoscopy is inserted to upper gastrointestinal tract via nasal cavity and the mobile device is set to take and send images from the endoscopy to a server for analyzing if the abnormal condition occurs.

The real-time upper gastrointestinal monitoring system is compared with the current monitoring index. The efficacy is estimated by which monitoring method finding the upper gastrointestinal rebleeding first.

The accuracy of the current monitoring index and the real-time upper gastrointestinal monitoring system is compared. The accuracy is estimated by calculating the ratio of the number of making false alarm and the number of finding re-bleeding right.