## 2 Related Work  
Nowadays, digital signage technology has developed rapidly along with IoT and mobile applications in various fields of our life, such as entertainment, education, advertisement, early warning systems, and especially in industrial IoT applications. A combination of commercial and emergency monitoring systems is developing to help people and manufacturers monitor critical facilities, such as schools, hospitals, and factories. Apart from central facilities and buildings, emergency monitor and evacuation applications and systems are developing to help people evacuate aircraft, trains, and ships. To this end, researchers focused on IoT-enabled digital signage systems, which can be combined with sensors, to gather and analyze sensitive data like dangerous gases and temperature, perform monitoring and warning functions, and direct passengers to the emergency exit and the evacuation points. Thus, as well as an improvement in emergency evacuation procedure being reached, people who live or work inside buildings, or travel by public transportation, feel safe as they know that in case of emergency, there is a well-known plan to abandon the structure or the means of travel. In this section, we present some related work on digital signage and emergency evacuation systems. [PERSON] et al. [11] proposed a new signage system in conjunction with an IoT platform, where the trusted information is provided through their intelligent smart signage services. Their system displays personalized and optimized content for various situations and controls the selected based on situation awareness. They have designed a trust information subsystem to support the intelligence of situation awareness and personalize features in intelligent signage services. They have modeled a trusted relationship between two things, as a six-tuple relationship that contains two trust things, one trust value, one trust scope, one trust type, and one trust validation. They also propose a system that can connect hub technology along with an IoT platform and utilize trust analysis technology between people and objects in a digital service. In our digital signage system, we have included sensors and intelligent functions that can automatically redirect passengers to a safer route in case that the initially selected is closed for some safety reasons. Another approach is evolving digital signage while providing personalized service by adaptively changing content, as revised by [PERSON] et al. [12]. Their digital system aimed to solve two problems. Firstly, digital signage systems have difficulty expanding their services because it is not easy to connect to additional sensing devices. Secondly, previous digital signage systems do not consider multiple signages per service. They propose a platform that provides IoT-based connectivity between the IoT platform, and multiple sensors, as a flexible service extension. They also suggest an IoT-based signage connection and centralization and service for the controlling of sensors' status. Thus, the platform can dynamically create a service group of signages, providing collaborating signages for services in wide areas. To test platforms' performance, they created a smart nursing home service, which uses a smart band to monitor users' health status and detect emergencies. The digital signage service that we propose can expand without limitation. Furthermore, sensors can publish and receive multiple messages from multiple MQTT topics that represent MVZs. We can control the services from an IoT dashboard, where we can see all installed sensors' statuses on the ship. Moreover, we cover a wide area, and passengers do not have to wear any smart band or sensor because multiple sensors on the ship detect emergencies and dynamically inform the IoT dashboard. [PERSON] et al. [13] devised a system that, if there is a fire emergency, reduces people's congestion and speeds up the whole process by dynamically directing people to the safest exit.