## 3 Materials and Methods
### Integrated Monitoring Platform Web Application
This makes it easy to manage where the sensors of each device are installed in an environment where several devices of the same configuration are installed. The installation information also includes the installation end date and time, so that the history of past installation information can be traced back. The device_data_csv manages the CSV files of the measurement data stored on the SD card of the measurement device. The purpose of this function is to enable easy management of the conditions under which the CSV files generated when using multiple devices of the same configuration were measured. Even when only one device is used, this function facilitates data analysis during the trial-and-error phase of data acquisition, when considering which part of an industrial machine to install a sensor. The sensor_installation_info manages the individual data measured by sensors. The target data here are data such as sound data, image data and video data, which do not contain multiple sensor data in one file. These data cannot be registered in the database as they are because the file size is expected to be large. The system uploads sensor data files to a folder on the server and registers the path to the files in the database. This makes it possible to download sensor data later and analyse them under specific measurement conditions. The gateways manage data aggregation gateways used during data collection. The gateways described here are devices that receive data sent from multiple measurement devices using wired or wireless communication, aggregate them and send them to the server. When sending data from the gateway to the server, the HTTP request is first sent using a TCP connection. The gateway first establishes the TCP connection by using the server's IP address and port number. The server is waiting on the specified port, and once the TCP connection is established, it receives the HTTP request. The HTTP POST request is sent from the gateway to the server via the TCP/IP network. This request contains header information and the data to be sent. Therefore, it is necessary to interpret the payload of the received HTTP POST packet and convert it into the device's data In this system, the format of the packet body part of the HTTP POST is not handled by the operator, but by the system implementation. In other words, the system does not support a gateway with a different HTTP POST packet body part format from the assumed gateway. This is because there is no common data format for gateways. However, it is possible to support this by additionally defining which part of the HTTP POST packet body part is the transmission data on the server side. As the format of the transmitted data depends on the implementation of the measurement device, the definition of the format of the transmitted data can be edited by the operator of this system. In this research, a LoRa gateway, ES920 GWX2 manufactured by EASEL Inc. (Kana-gawa, Japan) [15], is used as the gateway. This LoRa gateway receives data sent by the company's LoRa module ES920 LR2 and sends the data to the server via HTTP POST usingan Ethernet connection or LTE communication using a SIM card. The body of the packet sent by the LoRa gateway to the server is a character string and has the following format. gwid=XX&ch=XX&sf=XX&rssi=XX&panid=XX&id=XX&Sensor unit transmission data  
where gwid is the ID of the ES920 GWX2, ch is the radio channel, sf is the spreading factor, rssi is the received signal strength, pandi is the network address and id is the ID of the source module. This format combines information on the source and communication with the transmitted data using the ampersand as a delimiter. Therefore, when data in this format are received by a server, the strings below the sixth ampersand can be treated as transmission data. However, as the extracted transmission data may contain multiple data, it is necessary to cast these further.