기계공학 PDF 2021-4
http://www.dprkmedia.com.009911nz0067.erf.sbb.spk-berlin.de/Uploaded/Journal/2106/KPJ_80494.pdf
Mechanical Engineering (dprkmedia) January 07, 2022
http://www.dprkmedia.com.009911nz0067.erf.sbb.spk-berlin.de/Uploaded/Journal/2106/KPJ_80494.pdf