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A deburring strategy in drilled hole of CFRP composites using EDM process
Islam, Md. Mofizul,Li, Chang Ping,Won, Sung Jae,Ko, Tae Jo ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.703 No.-
<P><B>Abstract</B></P> <P>Carbon fiber reinforced plastic (CFRP) composites are highly promising materials for applications in the aeronautic and aerospace industry due to their superior strength-to weight and stiffness-to-weight ratios. Drilling of CFRPs composites is an important machining operation in the aerospace industry. However, during drilling of CFRPs, the formation of burrs are always severe shortcomings. In most machining processes, burrs are an undesired by-product cause many problems in assembly, inspection, process automation and precision component operation. To address this problem, this study introduced electrical discharge machining (EDM) as a deburring method for removal of burrs which are generated during drilling of CFRP composites. Four types of cylindrical tool namely copper, steel, brass and aluminium were used as the electrode for deburring. Deburring was carried out at various capacitance and time with different electrode materials. Experimental results demonstrated that the generated burrs of the drilled hole were successfully removed by the proposed deburring method. The copper electrode proved the better performance than others electrode in terms of deburring time and material removal rate. On the other hand aluminium electrode obtained lowest performance. The suggested deburring technique is effective for removal of the drilling burrs in conductive materials regardless of their hardness, because of the EDM deburring uses electrical discharge and its thermal energy without mechanical contact between the tool and workpiece.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A deburring method has been developed using EDM for removal of burrs from CFRP. </LI> <LI> Generated burrs of the drilled hole were successfully removed by the proposed method. </LI> <LI> Copper electrode obtained the highest performance among the four electrodes. </LI> <LI> No morphological changes were observed in drilled hole after deburring. </LI> </UL> </P>
Mechanism analysis of hybrid machining process comprising EDM and end milling
Li, Chang Ping,Kim, Min-Yeop,Islam, Md. Mofizul,Ko, Tae Jo Elsevier 2016 Journal of materials processing technology Vol.237 No.-
<P><B>Abstract</B></P> <P>STD 11 alloy steel is an extremely hard and difficult-to-cut material that is used extensively in cutter and die manufacturing for its superior wear resistance. This paper introduces a hybrid machining process (HMP) based on EDM and end milling (EDM-end milling) as an effective method for machining difficult materials. The HMP combines cutting action and an electrical thermal process. The machining mechanism was investigated, and a mathematical model of EDM-end milling is presented. Simulated and experimental cutting results were compared to validate the model. A tungsten carbide end mill was used as a tool electrode to machine STD 11 alloy steel (H<SUB>R</SUB>C 60) with different electric energy pulses. The results show that the method greatly improves tool wear and machining efficiency.</P>
Li, Chen-Long,Chang, Liang,Guo, Lin,Zhao, Dan,Liu, Hui-Bin,Wang, Qiu-Shi,Zhang, Ping,Du, Wen-Zhong,Liu, Xing,Zhang, Hai-Tao,Liu, Yang,Zhang, Yao,Xie, Jing-Hong,Ming, Jian-Guang,Cui, Yu-Qiong,Sun, Ying Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.23
Background: ${\beta}$-elemene, extracted from herb medicine Curcuma wenyujin has potent anti-tumor effects in various cancer cell lines. However, the activity of ${\beta}$-elemene against glioma cells remains unclear. In the present study, we assessed effects of ${\beta}$-elemene on human glioma cells and explored the underlying mechanism. Materials and Methods: Human glioma U87 cells were used. Cell proliferation was determined with MTT assay and colony formation assay to detect the effect of ${\beta}$-elemene at different doses and times. Fluorescence microscopy was used to observe cell apoptosis with Hoechst 33258 staining and change of glioma apoptosis and cell cycling were analyzed by flow cytometry. Real-time quantitative PCR and Western-blotting assay were performed to investigated the influence of ${\beta}$-elemene on expression levels of Fas/FasL, caspase-3, Bcl-2 and Bax. The experiment was divided into two groups: the blank control group and ${\beta}$-elemne treatment group. Results: With increase in the concentration of ${\beta}$-elemene, cytotoxic effects were enhanced in the glioma cell line and the concentration of inhibited cell viability ($IC_{50}$) was $48.5{\mu}g/mL$ for 24h. ${\beta}$-elemene could induce cell cycle arrest in the G0/G1 phase. With Hoechst 33258 staining, apoptotic nuclear morphological changes were observed. Activation of caspase-3,-8 and -9 was increased and the pro-apoptotic factors Fas/FasL and Bax were upregulated, while the anti-apoptotic Bcl-2 was downregulated after treatment with ${\beta}$-elemene at both mRNA and protein levels. Furthermore, proliferation and colony formation by U87 cells were inhibited by ${\beta}$-elemene in a time and does-dependent manner. Conclusions: Our results indicate that ${\beta}$-elemene inhibits growth and induces apoptosis of human glioma cells in vitro. The induction of apoptosis appears to be related with the upregulation of Fas/FasL and Bax, activation of caspase-3,-8 and -9 and downregulation of Bcl-2, which then trigger major apoptotic cascades.
A Study on the Development of Rotary Ultrasonic Machining Spindle
Chang-Ping Li(이상평),Min-Yeop Kim(김민엽),Jong-Kweon Park(박종권),Tae-Jo Ko(고태조) 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.4
Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is 5.4 μm noted at the frequency of 40 ㎑. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.
Cases Studies on Total Productive Management and Competitive Advantages
Li, chang-chung,Tsai, Ping-chen 한국품질경영학회 2001 The Asian Journal on Quality Vol.2 No.1
The purpose of business strategy is to achieve competitive advantages which includes higher efficiency, better quality, more innovation and faster customer response. In other words, The business strategy is to build unique capability of lower cost and/or differentiation. In production aspect, unique capability means better production power with better performance at 3M(Man, Machine, Material) of input and PQCDSM (Product, Quality, Cost, Delivery, Safety, Moral) from output. The Total Productive management (TPM), a series of improvement activities focused on reduction of equipment loss, is a tool to establish business competitive advantages. In this paper, several domestic companies who won the Japan TPM Award have been studied. It is found that there is a strong cause-effect relationship between TPM and competitive advantages because. 1. TPM can change employees mindset effectively. 2. TPM can upgrade employees capabilities. 3. TPM can lead to excellent productivity.
Ping Li,Xin Liu,Zouwei Li,Younghoon Chang 한국경영정보학회 2021 한국경영정보학회 학술대회논문집 Vol.2021 No.11
Founded on social network theory, this study will recruit 168 patients in an online health community as the research subject, and uses Poisson regression model to investigate the impact of network structure characteristics on user participation behavior. This study contributes to the body of knowledge in the online medical field and provides practical implications to the managers of online health platforms.
JCAD deficiency attenuates activation of hepatic stellate cells and cholestatic fibrosis
Li Xie,Hui Chen,Li Zhang,Yue Ma,Yuan Zhou,Yong-Yu Yang,Chang Liu,Yu-Li Wang,Ya-Jun Yan,Jia Ding,Xiao Teng,Qiang Yang,Xiu-Ping Liu,Jian Wu 대한간학회 2024 Clinical and Molecular Hepatology(대한간학회지) Vol.30 No.2
Background/Aims: Cholestatic liver diseases including primary biliary cholangitis (PBC) are associated with active hepatic fibrogenesis, which ultimately progresses to cirrhosis. Activated hepatic stellate cells (HSCs) are the main fibrogenic effectors in response to cholangiocyte damage. JCAD regulates cell proliferation and malignant transformation in nonalcoholic steatoheaptitis-associated hepatocellular carcinoma (NASH-HCC). However, its participation in cholestatic fibrosis has not been explored yet. Methods: Serial sections of liver tissue of PBC patients were stained with immunofluorescence. Hepatic fibrosis was induced by bile duct ligation (BDL) in wild-type (WT), global JCAD knockout mice (JCAD-KO) and HSC-specific JCAD knockout mice (HSC-JCAD-KO), and evaluated by histopathology and biochemical tests. In situ-activated HSCs isolated from BDL mice were used to determine effects of JCAD on HSC activation. Results: In consistence with staining of liver sections from PBC patients, immunofluorescent staining revealed that JCAD expression was identified in smooth muscle α-actin (α-SMA)-positive fibroblast-like cells and was significantly up-regulated in WT mice with BDL. JCAD deficiency remarkably ameliorated BDL-induced hepatic injury and fibrosis, as documented by liver hydroxyproline content, when compared to WT mice with BDL. Histopathologically, collagen deposition was dramatically reduced in both JCAD-KO and HSC-JCAD-KO mice compared to WT mice, as visualized by Trichrome staining and semi-quantitative scores. Moreover, JCAD deprivation significantly attenuated in situ HSC activation and reduced expression of fibrotic genes after BDL. Conclusions: JCAD deficiency effectively suppressed hepatic fibrosis induced by BDL in mice, and the underlying mechanisms are largely through suppressed Hippo-YAP signaling activity in HSCs.