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Friction Experiment of Linear Motion Roller Guide THK SRG25
De-Jun Cheng,김수진,양완석,박재홍,박태조,김경호,박천홍 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Friction is a characteristic that can be found in machine elements in common engineering use, and it has great effect on the machining performance of a machine tool. Linear motion (LM) guides supported by rolling elements are used for accurate positioning of precision machine. For accurate positioning, the frictional behavior of the LM guide must be understood. In this investigation, a new experiment is conducted to measure friction, and the behavior of LM roller guide friction is measured under various external loads, preloads, velocities, and lubricants. The results obtained from experiment are compared with reference data, and the experimental friction equation of LM roller guide THK SRG25 is achieved from experiment, which can be used to calculate LM roller guide friction and control positioning accuracy.
Friction Experiment of Linear Motion Roller Guide THK SRG25
Cheng, De-Jun,Yang, Wan-Suk,Park, Je-Hong,Park, Tae-Jo,Kim, Su-Jin,Kim, Gyung-Ho,Park, Chun-Hong 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.3
Friction is a characteristic that can be found in machine elements in common engineering use, and it has great effect on the machining performance of a machine tool. Linear motion (LM) guides supported by rolling elements are used for accurate positioning of precision machine. For accurate positioning, the frictional behavior of the LM guide must be understood. In this investigation, a new experiment is conducted to measure friction, and the behavior of LM roller guide friction is measured under various external loads, preloads, velocities, and lubricants. The results obtained from experiment are compared with reference data, and the experimental friction equation of LM roller guide THK SRG25 is achieved from experiment, which can be used to calculate LM roller guide friction and control positioning accuracy.
Minimization of Surface Roughness and Machining Deformation in Milling of Al Alloy Thin-Walled Parts
De-Jun Cheng,Feng Xu,Sheng-Hao Xu,Chun-Yan Zhang,Sheng-Wen Zhang,Su-Jin Kim 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9
This study focused on investigating the surface roughness in the feed direction (R a -Fd), surface roughness in the transversedirection (R a -Td), and thin-walled parts deformation (TWD) during milling of Al alloy 5083. The response surface method(RSM) was used to conduct experiments and establish the models of R a -Fd , R a -Td , and TWD under various cutting parameters. The significance of cutting parameters on R a -Fd , R a -Td , and TWD was analyzed by analysis of variance. It was observedthat the R a -Fd and R a -Td are mainly influenced by the spindle speed, depth of cut, transverse size and feed rate, while the TWD is mainly influenced by the depth of cut. A comparison of RSM-optimum function and artificial bee colony (ABC)algorithm optimum programming was conducted to obtain the best cutting conditions leading to minimum R a -Fd, R a -Td and TWD simultaneously. From the presented results, ABC algorithm was able to obtain the better cutting strategy. Finally, theperformance of the proposed cutting strategy was verified by confirmation experiments.
De-Jun Cheng,Jie Zhang,Zhong-Tai Hu,Sheng-Hao Xu,Xi-Feng Fang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.10
This paper aims to propose a digital twin-driven (DTD) approach that consists of the machining data (MD) in twin data (TD), design of MD acquisition methodology, construction of intelligent algorithm, real-virtual data interaction analysis and fusion technology, which improvs the predictability and management of on-line quality control of marine diesel engine (MDE) critical parts. Firstly, this paper introduces the theoretical framework of DTD on-line quality control in machining process. Secondly, we construct the process of DTD on-line quality control and introduce the digital twin model of on-line quality control based on TD-driven; the operation of data-driven quality on-line control based on digital twin including description and modeling of MD; acquisition of MD based on digital twin; TD-driven on-line tool life prediction and data fusion on-line machining parameters optimization methods. Finally, a case study is applied to validate the accuracy and availability of the DTD approach. The proposed approach provides a new way for the on-line quality control of MDE critical parts in machining process.
De-Jun Cheng,박제홍,서정세,김수진,박천홍 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3
The temperature distribution in roller Linear motion (LM) rail surface heated with moving frictional heat source was investigated experimentally and numerically. The operating conditions which had not been regarded by previous research, such as the type of the LM guide and operating temperature, were taken into account for improving the previous model of friction force. Frictional heat generation model and heat partitioning coefficient were proposed to calculate the heat transferred to the LM rail. The numerical solutions were calculated in combining a heat conduction equation and the rate of frictional heat flowing into the rail. Frictional heat generation model and heat partitioning coefficient were verified by comparing experimental and numerical results. Simulation results showed that smaller LM block size or higher velocity leads to the higher temperature distribution in the rail surface. Results also indicated that larger motion stroke results in a lower and wider temperature distribution in the rail surface.
Sun, De Jun,Liu, Ying,Lu, Dong Cheng,Kim, Woonbong,Lee, Je Ho,Maynard, Jonathan,Deisseroth, Albert Elsevier 2007 Human pathology Vol.38 No.7
<P><B>Summary</B></P> <P>We used cDNA microarray analysis of RNA extracted from normal, dysplastic, and cancerous cervical tissues to identify the changes in gene expression during the procession from normal to cancerous cervical epithelial cells. We found the expression of 5 genes in cancerous cervical epithelial cells that were not found in normal cervical epithelial cells, among which were lymphoid-restricted membrane protein, protease serine 2, WD repeat domain 59, thyrotropin-releasing hormone degrading enzyme, and the endothelin-3 growth factor. We then analyzed the expression levels of endothelin growth factors 1, 2, and 3 (ET-1, ET-2, and ET-3) and their receptors A and B (ETR-A and ETR-B) by reverse transcriptase-polymerase chain reaction in 3 cervical cancer cell lines and by immunohistochemical staining in cervical normal, dysplastic, and cancer tissues. ET-1, ET-2, and ET-3 growth factor levels were detectable in the maturing layer of cervical epithelium but not in the germinal layer. All 3 growth factors (ET-1, ET-2, and ET-3) were detected in the cytoplasm of the maturing normal cervical epithelial cells. In addition, there were decreased levels of ET-3 and increased levels of ET-1, ET-2, ETR-A, and ETR-B in cancerous cervical epithelial cells compared with normal cervical epithelial cells. These results suggest that the reduction of ET-3 growth factor levels may be important in the transition from normal to cancerous cervical epithelium.</P>
Ng Jyi Cheng,Ahmad Zaidi Ahmad Ibrahim,Lee Jun De,Jabar Mohd Faisal 대한성형외과학회 2023 Archives of Plastic Surgery Vol.50 No.6
Necrotizing fasciitis is an uncommon yet fatal soft tissue infection. Current recommended treatment includes antibiotics with repeat surgical exploration and wound debridement followed by reconstruction. In burn patients, the Meek micrograft has demonstrated a higher true expansion ratio, faster reepithelialization rate, more resilient toward infection, and reduced risk of graft failure as compared with meshed graft. To our best knowledge, the use of Meek micrografting technique in reconstruction of postdebridement wounds of necrotizing fasciitis has not been reported. Hereby, we present a case of a 57-year-old gentleman who was referred to us for wound reconstruction after surgical debridement of Fournier's gangrene and extensive necrotizing fasciitis involving the anterior abdomen and bilateral femoral region. Meek micrografting technique was used to reconstruct the anterior abdomen as the wound bed was large. Although the graft was complicated with a small area of localized infection, it did not spread across the entire graft and was successfully treated with topical antibiotics and regular wound dressing. In our case, wound reconstruction using Meek micrografting technique in a patient with extensive necrotizing fasciitis was successful and showed positive outcome. Therefore, we suggest further studies to be conducted to investigate the applications and outcomes of the Meek micrografting technique, especially in patients with extensive wound bed and limited donor site availability.
Identification of Specific Gene Modules in Mouse Lung Tissue Exposed to Cigarette Smoke
Xing, Yong-Hua,Zhang, Jun-Ling,Lu, Lu,Li, De-Guan,Wang, Yue-Ying,Huang, Song,Li, Cheng-Cheng,Zhang, Zhu-Bo,Li, Jian-Guo,Xu, Guo-Shun,Meng, Ai-Min Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.10
Background: Exposure to cigarette may affect human health and increase risk of a wide range of diseases including pulmonary diseases, such as chronic obstructive pulmonary disease (COPD), asthma, lung fibrosis and lung cancer. However, the molecular mechanisms of pathogenesis induced by cigarettes still remain obscure even with extensive studies. With systemic view, we attempted to identify the specific gene modules that might relate to injury caused by cigarette smoke and identify hub genes for potential therapeutic targets or biomarkers from specific gene modules. Materials and Methods: The dataset GSE18344 was downloaded from the Gene Expression Omnibus (GEO) and divided into mouse cigarette smoke exposure and control groups. Subsequently, weighted gene co-expression network analysis (WGCNA) was used to construct a gene co-expression network for each group and detected specific gene modules of cigarette smoke exposure by comparison. Results: A total of ten specific gene modules were identified only in the cigarette smoke exposure group but not in the control group. Seven hub genes were identified as well, including Fip1l1, Anp32a, Acsl4, Evl, Sdc1, Arap3 and Cd52. Conclusions: Specific gene modules may provide better understanding of molecular mechanisms, and hub genes are potential candidates of therapeutic targets that may possible improve development of novel treatment approaches.