Funding for this research was provided by:
Thailand Research Fund (Distinguished Research Professor Grant, grant no. DPG6280002)
Khon Kaen University (Scholarship under Doctoral Training Program from Graduate School and Research Affairs, grant number 60164)
Text and Data Mining valid from 2019-11-22
Received: 24 August 2019
Accepted: 21 October 2019
First Online: 22 November 2019
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.
: All procedures performed in studies involving human participants were in accordance with ethical standards of the Khon Kaen University Ethics Committee for Human Research (HE611507) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.