1. Department of Light Industry Machinery Engineering, Pyongyang University of Mechanical Engineering, Pyongyang 999093, Democratic People’s Republic of Korea
2. School of Physical Science, Kim Chaek University of Technology, Yonggwang Street, Pyongyang 999093, Democratic People’s Republic of Korea
3. Faculty of Forest Science, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea
4. College of Ship and Ocean Technology, Kim Chaek University of Technology, Pyongyang 999093, Democratic People’s Republic of Korea
5. Institute of Mechanical Engineering, Academy of Sciences, Pyongyang 999093, Democratic People’s Republic of Korea