**Acknowledgements**

This work has received funding from the Nihon University Chairman of the Board of Trustees Grant and the Nihon University President Grant Initiative.

### **Conflict of interest**

The authors declare no conflict of interest.

### **Notes/thanks/other declarations**

We would like to thank Mr. Kenei Shie, President of ViewSend ICT for providing technical support for the activities of this research project for more than 10 years.
