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      • KCI등재

        Modification of tool influence function for bonnet polishing tool based on analysis of interfacial contact state

        Ri Pan,Xiangxiang Zhu,Zhenzhong Wang,Dongju Chen,Shuting Ji,Jinwei Fan,Rui Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

        The polishing mechanism of bonnet polishing (BP) and the tool influence function (TIF) of bonnet tool have been widely studied. However, most of current studies pay little attention to the influence of polishing slurry on the BP mechanism as well as TIF. This study proposes that the interfacial contact state between the polishing tool and the workpiece is in a mixed lubrication state, subsequently the BP mechanism is further explored. It is found that the workpiece material is removed by polishing pad and abrasives. The polishing slurry is not directly involved in workpiece removal, but shares the normal pressure of the polishing tool on workpiece, which affects material removal. Based on the above mechanism, the TIF removal prediction model is established and verified by experiments. The results show that the maximum error of the model prediction value is quiet small, which verifies the model. Moreover, compared with Preston model and the previous model, which ignored the influence of the fluid, the average prediction error of the model in this paper when D 0 = 20 mm is 6.38 %, while the previous model and Preston model are 11.21 % and 49.10 %, respectively. Which illustrates the model in this paper has higher accuracy.

      • KCI등재

        Research on Control Optimization for Bonnet Polishing System

        Pan Ri,Wang Zhen-Zhong,Wang Chun-Jin,Xie Yin-Hui,Zhang Dong-Xu,Guo Yin-Biao 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

        Aspheric optical lenses are conventionally polished with continuous precession by 5-axis bonnet polishing system. In this work, in order to achieve that aspheric lenses be processed by four-axis simultaneous NC (numerical control) machining system, one kind of control algorithm was proposed by controlling the error of precession angle. Firstly, on the basis of the analysis of the structure of bonnet tool and processing technology of aspheric optics, ranges of important parameters in machining process such as the angle between spin axis of bonnet tool and negative vertical direction and the precession angle were fixed, to make the minimum errors of precession angle as small as possible; Secondly, the control algorithm was introduced, aimed to reduce the existing errors of precession angle in polishing process by making micro migration of machining points. Then, simulation experiments of polishing non-axisymmetric aspheric lenses were carried out to validate the suggested control algorithm, the results revealed that the maximum error of precession angle was decreased to about 0.01°, which is available in real processing.

      • KCI등재

        Optimization Strategy on Conformal Polishing of Precision Optics using Bonnet Tool

        Ri Pan,Yajun Zhang,Jianbiao Ding,Changqing Huang,Zhenzhong Wang 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.3

        For the purpose of optimizing the polishing process of ultra-precision optics, the optimal motion for bonnet tool used in conformal polishing (CP) is investigated. Firstly, the removal mechanism in CP was studied and analyzed, based on which the conformal polishing conditions (CPC) and the conclusion that sub-steps precession (S-s-P) is the optimal motion were obtained; After that, corresponding simulations and experiments were conducted, and the results revealed that (1) the ability for CP of continuous precession (Con-P) was not stable, and only when the round distance S and the total polishing length are sufficiently tiny and large, meanwhile, S / vfx = 2*π/ωA is satisfied, the conformal polishing performance of Con-P is good. However, these requirements would limit its application in engineering; (2) Both the incline polishing (IP) and S-s-P models have good performance on CP, and their abilities for CP were not affected by the feeding speed. However, since the texture of the polished area of IP is not so good as S-s- P, the later is the most favourite model in CP. All the results have proven the correctness of the CPC and the theoretical conclusion, which is useful for the engineering application of S-s-P model of bonnet tool.

      • KCI등재

        Optimization Strategy on Conformal Polishing of Precision Optics using Bonnet Tool

        Ri Pan,Yajun Zhang,Jianbiao Ding,Changqing Huang,Zhenzhong Wang 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.5

        For the purpose of optimizing the polishing process of ultra-precision optics, the optimal motion for bonnet tool used in conformal polishing (CP) is investigated. Firstly, the removal mechanism in CP was studied and analyzed, based on which the conformal polishing conditions (CPC) and the conclusion that sub-steps precession (S-s-P) is the optimal motion were obtained; After that, corresponding simulations and experiments were conducted, and the results revealed that (1) the ability for CP of continuous precession (Con-P) was not stable, and only when the round distance S and the total polishing length are sufficiently tiny and large, meanwhile, S / vfx = 2*π/ωA is satisfied, the conformal polishing performance of Con-P is good. However, these requirements would limit its application in engineering; (2) Both the incline polishing (IP) and S-s-P models have good performance on CP, and their abilities for CP were not affected by the feeding speed. However, since the texture of the polished area of IP is not so good as S-s-P, the later is the most favourite model in CP. All the results have proven the correctness of the CPC and the theoretical conclusion, which is useful for the engineering application of S-s-P model of bonnet tool.

      • KCI등재

        An Egg-Shaped Elastic Viscoplastic Model for Clay: Experimental Investigation and Constitutive Modelling

        Pan Ding,Luying Ju,Ri-Qing Xu,Zihai Yan,Mingming Wu,Gangping Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

        This paper presents the experimental investigation carried out for evaluation of the rheological behaviours of Hangzhou soft clay, and proposes a three-dimensional elastic viscoplastic model to describe the rheological characteristics under triaxial condition. Firstly, the time-dependent behaviours of Hangzhou soft clay, such as creep and strain rate effects, were observed and discussed based on the analysis of rheological tests. Subsequently, a constitutive model was formulated under the framework of Perzyna’s overstress theory and incorporates other developments, including: 1) A smooth and continuous egg-shaped yield surface, whose shape can change from an ellipse to a teardrop shape, thus providing greater flexibility for better modelling; 2) An equivalent time concept, which enables the model to describe the time-dependent behaviours under different loading paths. By varying the shape parameter, the newly established model can be degenerated into modified Cam-clay (MCC) model or Yin-Graham elastic viscoplastic model. Finally, the model was solved numerically using the fourth-order convergent iterative method combined with the Runge-Kutta method. Comparison of simulation results and experimental data shows that the newly proposed model has an ability to predict creep characteristics and strain rate effects of soft clay.

      • KCI등재

        척추질환 예방용 4개 관절 기반 모션캡쳐 시스템 연구

        고경리(Kyeong-Ri Ko),채승훈(Seung-Hoon Chae),배성봉(Seong Bong Bae),최장식(Jang Sik Choi),반성범(Sung Bum Pan) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.8

        Bad posture triggers spinal diseases by forming a twisted or crooked body. Therefore, it is vital for modern people mostly living a sedentary lifestyle to have correct posture. In this paper, we construct a reasonably priced motion capture system requiring less preparation time and measurement space by using small-sized and lightweight micro electro-mechanical systems-based wireless inertial sensors to address the problems with the existing motion capture system. In addition, we have acquired and analyzed 4-joint motion data. The analysis results show that the motion data of four joints acquired through the embodied system can be applied to the self-coaching system, and users can employ the system for spinal disease diagnosis themselves.

      • KCI등재

        셀프-코칭을 위한 관성센서 기반 인체모션 취득 시스템 구현

        고경리(Kyeong-Ri Ko),배성봉(Seong Bong Bae),최장식(Jang Sik Choi),반성범(Sung Bum Pan) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.4

        Recently due to the increasing attention paid to personal education, medical welfare, leisure sports and other leisure activities, various self-coaching systems are being developed for education, rehabilitation exercises and sports for self-learning without external help. In this paper, we explain the human motion capturing system for realization of a self-coaching system, and present the results of the captured human motions using this system. The human body model based motion capture system comprises 15 inertial sensors, a 3-channel receiver, a human body model based 3-dimensional simulation program, and a personal computer. We experiments of subjects motion data obtaining using the commercial motion capture system for verification of construction motion capture system. As a result, the expert and user takes action was appear equally on three-dimensional simulation.

      • KCI등재

        골프 셀프-코칭 시스템을 위한 인체모델 기반 골프 스윙 모션 데이터 취득

        고경리(Kyeong-Ri Ko),반성범(Sung Bum Pan) 한국정보기술학회 2015 한국정보기술학회논문지 Vol.13 No.8

        As the golf population increase, the concern with individual swing posture analysis and diagnosis has been growing. To prevent injuries caused by incorrect swing and golf swing capability upgrade. For the golf swing posture analysis and diagnosis, it is important that analysis of the swing motion and transmit information for posture correction can be performed to correction swing. The swing motion data acquisition of expert and user is needed for swing posture analysis. In this paper, human body model based golf swing motion data acquisition and explain. The motion data is full swing motion data of the teaching professional and the publics. It has acquired each 20 times using driver and 7 iron club. Swing motion comparison result, the differences appeared in the arm bend and straighten state, weight shift of lower body, bow head degree.

      • KCI등재

        4개 관절 기반 인체모션 분석을 위한 특징 추출 및 자세 분류

        고경리(Kyeong-Ri Ko),반성범(Sung Bum Pan) 대한전자공학회 2015 전자공학회논문지 Vol.52 No.6

        앉아있는 시간이 긴 현대인들에게 바른 자세를 유지하도록 하는 것은 중요하다. 자세 교정을 위한 치료는 많은 시간과 비용이 소요되며, 전문의의 지속적인 관찰이 필요하다. 그러므로 사용자 스스로 자신의 자세를 판단하고 교정하기 위한 시스템이 필요하다. 본 논문에서는 사용자의 자세 데이터를 취득하여 취득된 자세가 정상자세인지 비정상자세인지 판단한다. 사용자의 자세 데이터 취득을 위해 관성 센서를 이용한 4개 관절 기반 모션캡쳐 시스템을 제안한다. 이 시스템을 통해 대상자의 자세데이터를 취득하고, 취득한 데이터를 기반으로 특징을 추출하여 DB를 구축한다. 구축한 DB를 K-means 클러스터링 알고리즘을 이용하여 자세 학습을 수행한 후, 정상자세와 비정상자세를 분류한다. 관절의 회전각도, 위치정보, 분석정보를 이용하여 자세분류를 수행한 결과, 정상자세 판단 성공률은 99.79%로 나타났다. 이 결과로 미루어 4개 관절에 대한 특징을 이용하여 사용자의 자세를 판단 가능하며, 향후 척추질환 예방 시스템에 적용하여 사용자의 자세를 교정하는 데 도움을 줄 수 있을 것으로 판단된다. In the modern age, it is important for people to maintain a good sitting posture because they spend long hours sitting. Posture correction treatment requires a great deal of time and expenses with continuous observation by a specialist. Therefore, there is a need for a system with which users can judge and correct their postures on their own. In this study, we collected users’ postures and judged whether they are normal or abnormal. To obtain a user’s posture, we propose a four-joint motion capture system that uses inertial sensors. The system collects the subject’s postures, and features are extracted from the collected data to build a database. The data in the DB are classified into normal and abnormal postures after posture learning using the K-means clustering algorithm. An experiment was performed to classify the posture from the joints’ rotation angles and positions; the normal posture judgment reached a success rate of 99.79%. This result suggests that the features of the four joints can be used to judge and help correct a user’s posture through application to a spinal disease prevention system in the future.

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