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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.
Arm Exoskeleton Rehabilitation Robot with Assistive System for Patient after Stroke
Guan De Lee,Wei-Wen Wang,Kai-Wen Lee,Sheng-Yen Lin,Li-Chen Fu,Jin-Shin Lai,Wen-Shiang Chen,Jer-Junn Luh 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
Exercise dosage is proven to be an important factor in the physical treatment. Robot assistive approach can improve the rehabilitation quality and evaluate patient’s recovery quantitatively. This paper presents kinematic structure, assistive control system, and integrated F/T sensor for an upper limb rehabilitation robot. By using the human arm dynamic, there are three rehabilitation modes presented in this paper: active mode, assistive mode, and passive mode. In assistive mode, we have two strategies to implement it. One is to amplify interactive torque, and the other is to apply assist-as-needed concept. The goal of this mode is to assist patients to finish motion tasks. The rehabilitation robot under investigation has 7 degree of freedom (DOF) actuated by DC motors, which are programmed to drive the robot arm in the 3D space. To validate our control design, some realistic experiments are conducted and its satisfactory performance is demonstrated. This work is approved clinical testing by the Department of Health, Executive Yuan, R.O.C. So far, we are demonstrating the effect of our controller.
Purification of Capsular Polysaccharide Produced by Streptococcus pneumoniae Serotype 19A
( Seung Jin Jung ),( Eun Seong Seo ),( Sang Il Yun ),( Bui Nguyet Minh ),( Sheng De Jin ),( Hwa Ja Ryu ),( Do Man Kim ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.7
Streptococcus pneumoniae is a major cause of invasive infection in young infants and older adults. There are currently 90 capsular serotypes identified and 23 serotypes (1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F, and 33F) are responsible for about 90% of invasive disease. Among the more than 90 different S. pneumoniae serotypes, serotype 19A is globally very prevalent. A simplified purification procedure including adjustment of cell lysate pH to 4.5, fractionation with 50-80% ethanol, and dialysis rendered capsular polysaccharide (CPS) in a yield of 31.32 ± 3.11 mg from 1 l culture (75% recovery after lyses). The product contained only 69.6 μg of protein (99.78% purity) and 0.8mg (sum of the precipitants from 50~60%, 60~70%, and 70~80%) of nucleic acid (97.45% purity). The purified CPS was conjugated with bovine serum albumin; the product size ranged from 100 to 180 kDa.
Ultrasonic method for measuring the gas holdup of gas-liquid bubbly flow in a small-diameter pipe
Ning-De Jin,Zheng Gong,An Zhao,Lu-Sheng Zhai,Ying-Yu Ren 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.4
Based on ultrasonic sound pressure attenuation, the ultrasonic pulse transmission method is proposed for measuring gas holdup in gas-liquid two-phase bubbly flows. Two ultrasonic transducers are positioned on opposite sides of a vertical upward pipe with an inner diameter of 20 mm. To obtain the relationship between ultrasonic attenuation and gas holdup, the mean value of the first pulse sequence of ultrasonic signals is first extracted as the measured signal. We used the quick closing valve method to obtain the gas holdup as the set value. Second, the relationship between the gas holdup and measured ultrasonic signals was established. The experiment result shows that the ultrasonic attenuation rate is significantly different at low and high gas holdups, as indicated by the bubble size images with a high-speed camera. We also investigated the ultrasonic field distribution using numerical simulation. The bubble size has an important effect on the ultrasonic attenuation coefficient, which provides a further physical explanation and reference for the experimental phenomena.