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Kim, Eunseob,Shin, Yong-Jun,Ahn, Sung-Hoon MCB UNIVERSITY PRESS 2016 RAPID PROTOTYPING JOURNAL Vol.22 No.6
<P>Purpose - This paper aims to investigate the water absorption behaviors and mechanical properties, according to water absorption and temperature, of components fabricated by fused deposition modeling (FDM) and injection molding. The mechanical properties of FDM and injection molded parts were studied under several environmental conditions. Design/methodology/approach - FDM components can be used as load-carrying elements under a range of moisture and temperature conditions. FDM parts show anisotropic mechanical properties according to build orientation. Components were fabricated from acrylonitrile-butadiene-styrene in three different orientations. The mechanical properties of parts fabricated by FDM were compared to injection molded components made from the same material. Water absorption tests were conducted in distilled water between 20 and 60 degrees C to identify the maximum water absorption rate. Both moisture and temperature were considered as environmental variables in the tensile tests, which were conducted under various conditions to measure the effects on mechanical properties. Findings - The water absorption behavior of FDM components obeyed Fickian diffusion theory, irrespective of the temperature. High temperatures accelerated the diffusion rate, although the maximum water absorption rate was not affected. The tensile strength of FDM parts under dry, room temperature conditions, was approximately 26-56 per cent that of injection molded parts, depending on build orientation. Increased temperature and water absorption had a more significant effect on FDM parts than injection molded components. The tensile strength was decreased by 67-71 per cent in hot, wet environments compared with dry, room temperature conditions. Originality/value - The water absorption behavior of FDM components was investigated. The quantitative effects of temperature and moisture on tensile strength, modulus and strain were also measured. These results will contribute to the design of FDM parts for use under various environmental conditions.</P>
Power Consumption Assessment of Machine Tool Feed Drive Units
Hae-Sung Yoon,Jang-Yeob Lee,Min-Soo Kim,Eunseob Kim,Yong-Jun Shin,Sung-Yong Kim,Sangkee Min,Sung-Hoon Ahn 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.2
Numerous efforts have been made to assess and model the power consumption of machining process, which has led to many standards for energy labeling of machine tools. However, more investigation is required to improve the applicability of these standards because the energy patterns of machines vary widely with respect to the machine type, size, and configuration. Hence, it is aimed to develop a methodology to determine the power consumption characteristics of a wide variety of machine tools. This research focuses on the power consumption of feed drive units, which are largely varying components with respect to machine tool configurations. Two notable phenomena were observed during our experiments. First, the power consumption of an axis in the gravitational direction exhibited a different pattern from that along those of the other axes. Movement in the gravitational direction was investigated in more detail from the perspective of the machine tool configuration. Second, during multi-axis movement, no power correlation between different axes was confirmed. Regardless of the axis composition, no correlation was detected between the individual power consumption profiles of each axis. Elucidating the power consumption characteristics of feed drive units would contribute toward standardization and simplification of power measurement procedures.
Machine Learning for Object Recognition in Manufacturing Applications
Huitaek Yun,Eunseob Kim,Dong Min Kim,Hyung Wook Park,Martin Byung-Guk Jun 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4
Feature recognition and manufacturability analysis from computer-aided design (CAD) models are indispensable technologies for better decision making in manufacturing processes. It is important to transform the knowledge embedded within a CAD model to manufacturing instructions for companies to remain competitive as experienced baby-boomer experts are going to retire. Automatic feature recognition and computer-aided process planning have a long history in research, and recent developments regarding algorithms and computing power are bringing machine learning (ML) capability within reach of manufacturers. Feature recognition using ML has emerged as an alternative to conventional methods. This study reviews ML techniques to recognize objects, features, and construct process plans. It describes the potential for ML in object or feature recognition and offers insight into its implementation in various smart manufacturing applications. The study describes ML methods frequently used in manufacturing, with a brief introduction of underlying principles. After a review of conventional object recognition methods, the study discusses recent studies and outlooks on feature recognition and manufacturability analysis using ML.
Hybrid 3D printing by bridging micro/nano processes
Yoon, Hae-Sung,Jang, Ki-Hwan,Kim, Eunseob,Lee, Hyun-Taek,Ahn, Sung-Hoon IOP 2017 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.27 No.6
<P>A hybrid 3D printing process was developed for multiple-material/freeform nano-scale manufacturing. The process consisted of aerodynamically focused nanoparticle (AFN) printing, micro-machining, focused ion beam milling, and spin-coating. Theoretical and experimental investigations were carried out to improve the compatibility of each of the processes, enabling bridging of various different techniques. The resulting hybrid process could address the limitations of individual processes, enabling improved process scaling and dimensional degrees of freedom, without losing the advantages of the existing processes. The minimum structure width can be reduced to 50 nm using undercut structures. In addition, AFN printing employs particle impact for adhesion, and various inorganic materials are suitable for printing, including metals and functional ceramics. Using the developed system, we fabricated bi-material cantilevers for applications as a thermal actuator. The mechanical and thermal properties of the structure were investigated using an <I>in situ</I> measurement system, and irregular thermal phenomena due to the fabrication process were analyzed. We expect that this work will lead to improvements in the area of customized nano-scale manufacturing, as well as further improvements in manufacturing technology by combining different fabrication techniques.</P>