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| 2021, Vol. 24(1): 64-70 DOI: | ||
| Analysis of effects of operating parameters on rate of penetration in drilling process with air down － the － hole hammer | ||
| HO Yinchol ,PAK Kumdol ,PENG Jianming,ＲI Jaemyong , KIM Yongnam and CHOE Cholho | ||
| 1． School of Information Science and Technology，Kim Chaek University of Technology，Pyongyang 999093，D． P． Ｒ． Korea; 2． School of Ｒesource Exploration Engineering，Kim Chaek University of Technology，Pyongyang 999093，D． P． Ｒ． Korea; 3． College of Construction Engineering，Jilin University，Changchun 130026，China | ||
| Received null Revised null | ||
| Supporting info | ||
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