Papers by Author: Min Sung Hong

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Authors: Ki Hyun Kim, Dae Gab Gweon, Hyun Soo Jung, Soo Hun Lee, Min Sung Hong, Moon G. Lee
Abstract: Design of design of X-Y-Theta fine stage using VCM (voice coil motor) is presented in this paper. This fine stage is combined with linear DC motor. Long range, high speed and high precision of the stage is obtained by using dual servo control for laser micro/nano machining. A novel structure of VCM for the fine stage is proposed. The fine stage can have 3 DOF(X-Y-Theta) motion by four VCM actuators which are located on the same plane. The X-Y-Theta fine stage is designed to have high acceleration for high throughput. Based on the design, the stage is fabricated. The designed stage has the acceleration of 5m/s2 with 45kg total mass. In addition, this actuator is feedback controlled using HP laser interferometer. The reaction force between the coarse and fine stage of the dual servo is compensated by force compensator.
Authors: Min Sung Hong, Jong Min Kim, Noh Yu Kim
Abstract: Electron beam welding (EBW) has an important role in industrial applications such as semi-conductor and LCD manufactures because of its high performance and accuracy. Since the operation is done in a vacuum room, it is very difficult to test the weldability as well as the correct welding area of the specimen. In this study, a measurement system of the EBW was developed based on the 3-axis LVDT controlled table. In addition, the algorithm to tracking the welding line has been developed. The weldability of the aluminum specimen was tested by a newly developed measurement system with ultrasonic C-scan inspection.
Authors: Jong Min Kin, Min Sung Hong, Bong Suk Kim, Soo Hun Lee
Abstract: In conventional machining, cutting conditions such as cutting speed, feed rate, and depth of the cut have great influence on the surface roughness. In micro machining, however, the surface shape is affected by not only the machining parameters mentioned earlier but also tool stiffness, system stability, and workpiece properties caused by the miniatured structure and cutting tool. Especially, in a micro-machine system, the difference between the cutting forces in the recursive cuts introduces the vibration easily. A high spindle causes instability of the system, increases the temperature in the cutting process, and also changes the tool’s shape. This study introduces a method to predict the surface shape of the workpiece based on the machining conditions in micro milling. The micro-milled surfaces in different machining conditions are predicted by a computer simulation including the vibration model and the simulated results show good agreement with the experimental results.
Authors: Jun Suh Yu, Jae Chun Lee, Sung Park, Min Sung Hong
Authors: Noh Yu Kim, Hee Joon Kim, Se Woong Oh, N. Hozumi, Cheol Kyou Lee, Min Sung Hong
Abstract: In this paper, elastic moduli of nanostructured alumina are evaluated by simultaneous measurement of longitudinal and shear wave velocities using mode-converted ultrasound in scanning acoustic microscope (SAM). Mode-converted longitudinal and shear waves inside alumina sample are captured to calculate acoustic wave velocities and determine elastic constants such as Young’s modulus and Bulk modulus. Al2O3 nanostructured alumina samples are formed by compacting micro-sized Al2O3 powder with nano-sized Al2O3 powder from 10wt% to 50wt%, and tested by SAM to investigate elastic moduli. A correlation is found from experiment that the more percentage of nano-particles are added, the higher elastic moduli are obtained. It is also shown that the mode-converted ultrasound is sensitive enough to characterize mechanical modulus of nanostructured alumina quantitatively.
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