## 3 Future Directions of MES Development
### Development Directions for MES
#### Intelligent MES  
Figure 2: Future Manufacturing Execution System (MES) development directions. In terms of the intelligent MES, the manufacturing intelligence (MI) function is located in an area called a strategic layer at the top of the manufacturing layer in the MES area and the business layer in the ERP area, and it plays an important role in supporting optimal decision-making by utilizing manufacturing data and business data [28]. As such, MI functions go through the collection and synchronization process of structured data, such as process, PLC, vibration, power, and environmental sensor data collected in real time from MES systems and manufacturing sites, and unstructured data, such as documents, vision, and sound, and pre-processing for data analysis. Through these processes, various artificial intelligence services such as product-demand prediction, facility-failure diagnosis, and the manufacturing chatbot can be implemented. Regarding the optimal decision-making function, in the case of sportswear products, the target industry of this paper, the pressure from customers to move away from the traditional \"make-to-stock\" production model to \"build to demand\" customer service model, creates the need to leverage product information throughout the supply chain and greater visibility among the supply chain [51] to ensure customization and rapid delivery of innovative products [52]. In addition, if more companies use the \"cloud-based collaborative MES\" presented in this paper, the data collected (MES, ERP, facility, environment data, etc.) will also increase, at the same time, data shared among participating companies in the value chain will increase. Generally, supply chains show the characteristics of complex systems such as variety, uncertainty, and connectedness [53], Especially, as most of the time uncertainty cannot be removed from the supply chain [54], so it needs to be managed by obtaining as much decision-making information as possible [55]. To solve these problems, the entropy function can be regarded as a quantitative measure of uncertainty. As such, if the MES function is implemented to manage uncertainty in information sharing and to make optimal decisions, monitoring and management of the level of information shared between collaborating companies will be possible. (4) Collaborative MES  
With regard to the collaborative MES, as in the ERP's growth beyond the enterprise boundaries to have interorganizational collaboration for supporting emerging business requirements [56], the scope of MES has also been growing to include supply, design, and business functions of the manufacturing enterprise. Most existing MES systems have focused on single plants [57]. However, the recent literature reports MES systems with a wider focus on the value chain, such as the MES designed by [PERSON] et al. [31] for collaborative manufacturing in a multicompany supply chain. (5) MES mobility  
In terms of the MES mobility, recently, as intelligent mobile terminals spread to manufacturing sites, the response speed and mobility of data collected in real time are changing the production site management method, and this is one of the future development directions of MES [3]. Additionally, mobile solutions and device interfaces have become important factors in evaluating MES vendors over the past few years [36]. (6) Integration  
As suggested in ISA-95, the integration was proposed in terms of MES having to act as a link between the shop floor and the ERP. (7) Scalability and reconfigurability  
Scalability and reconfigurability were presented as the need to configure the MES system flexibly by considering the type of production system (job shop, flow shop, project shop, continuous process), size, and future process changes of the manufacturing company that intends to introduce MES.