• 한국정밀공학회지
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• 제26권11호
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• pp.99-107
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• 2009

Since a long work piece influences the natural frequency of the entire system with a miniature high speed spindle, a bar-feeder is used for a long work piece to improve the vibration characteristics of a spindle system. Therefore, it is very important to design optimally support positions between a bar-feeder and a long work piece for a miniature high speed spindle system. The goal of the current paper is to present an optimization method for the design of support positions between a bar-feeder and a long work piece. This optimization method is effectively composed of the method of design of experiment (DOE), the artificial neural network (ANN) and the genetic algorithm (GA). First, finite element models which include a high speed spindle, a long work piece and the support conditions of a bar-feeder were generated from the orthogonal array of the DOE method, and then the results of natural vibration analysis using FEM were provided for the learning inputs of the neural network. Finally, the design of bar-feeder support positions was optimized by the genetic algorithm method using the neural network approximations.

• 한국정밀공학회지
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• 제29권5호
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• pp.500-505
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• 2012

Recently, a high speed spindle is an essential part of machine tools to satisfy latest demand of high precision product and machining of hard materials. But, there are many disadvantages such as heat generation of built-in-motor, bearing friction, noise, vibration and displacement because of the high speed. Many researches on spindle systems have been conducted for solving these problems. In this study, technical trend of machine tools spindle systems are analyzed with patent PSM, mapping and grouping. The analysis is carried out for the applied patent during January 2000 and December 2009 in Korea, Japan, EU and U.S.A. And development of the direction, strategy and promising technologies of the spindle system are suggested.

• 한국기계가공학회지
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• 제4권1호
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• pp.18-23
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• 2005

This paper reports experimental results on microdrilling process for silicon parts used in semiconductor equipments. An experimental system was developed consisting of a high speed precision machine, microscope system, and project profile instrument. The experimental results indicate that the amount of chipping at the entrance and exit of micro hole decreases as the spindle speed increases up to 18,000 rpm. At higher spindle speed, however, the amount of chipping increases rapidly. The amount of chipping and infeed rate show proportional relationship up to 20 m/min of infeed rate. Beyond that infeed rate, however, sudden increase in the amount of chipping has occurred.

• 한국정밀공학회지
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• 제14권10호
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• pp.151-156
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• 1997

A laser measurement system, a modified Michelson interferometer, which can accurately measure high speed length and displacement of servomechanisms by detecting a phase shift in the measurement beam using an optical interference was developed. A frequency stabilized laser source and a 20 fold frequency interpolation and digitizing circuit were applied to the system. The refra- ctive index of the ambient air was calibrated through the Edlens formula. The system achieved a resolution of /40, 16nm, a maximum allow-able measurement speed of 600nm/sec, and a length measure- ment range of 1500 mm. Performance of the system was evaluated on the machining center in short and long length measurements.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.519-522
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• 2008

As industry of a semiconductor and LCD industry have been rapidly growing, precision technologies of machining such as etching and 3D measurement are required. Stylus has been important measuring method in traditional manufacturing process. However, its disadvantages are low measuring speed and damage possibility at contacting point. To overcome mentioned disadvantage, non-contacting measurement method is needed such as PMP(Phase Measuring Profilometry), WSI(white scanning interferometer) and Confocal Profilometry. Among above 3 well-known methods, WSI started to be applied to FPD(flat panel display) manufacturing process. Even though it overcomes 21t ambiguity of PMP method and can measure objects which has specular surface, the measuring speed and vibration coming from manufacturing machine are one of main issue to apply full automatic total inspection. In this study, We develop high speed WSI system and algorithm to reduce unknown noise. The developing WSI and algorithm are implemented to measure 3D surface of wafer. Experimental results revealed that the proposed system and algorithm are able to measure 3D surface profile of wafer with a good precision and high speed.

• Journal of Welding and Joining
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• 제28권3호
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• pp.42-48
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• 2010

Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) were welded by a combination of a diode laser and a CNC machining center. Laser beam delivered through the transparent PC and was absorbed in an opaque ABS. Polymers were melted and joined by absorbed and conducted heat. Experiments were carried out by varying working distance from 44mm to 50mm for the focus spot diameter control, laser input power from 10W to 25W, and scanning speed from 100 to 400mm/min. The weld bead and cross-section were analyzed for weld quality, and tensile results were presented through the joint force measurement. With focus distance at 48mm, laser power with 20W, and welding speed at 300mm/min, experimental results showed the best welding quality which bead size was measured to be 3.75mm. The shear strength at the given condition was $22.8N/mm^2$. Considering tensile strength of ABS is $43N/mm^2$, shear strength was sufficient to hold two materials. A single process was possible in a CNC machining system, surface processing, hole machining and welding. As a result, the process cycle time was reduced to 25%. Compared to a typical process, specimens were fabricated in a single process, with high precision.

• 한국기계가공학회지
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• 제18권7호
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• pp.56-62
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• 2019

The high-precision laser scriber carries out scribing alumina ceramic substrates for manufacturing ultra-small chip resistors. The ceramic substrates are loaded, aligned, scribed, transferred, and unloaded. The entire process is fully automated, thereby minimizing the scribing cycle time of the ceramic substrates and improving the throughput. The scriber consists of the laser optical system, pick-up module of ceramic substrates, pre-alignment module, TH axis drive work table, automation module for substrate loading / unloading, and high-speed scribing control S/W. The loader / unloader unit, which has the greatest influence on the scribing cycle time of the substrates, carries the substrates to the work table that carries out the cutting line work by driving the X and Y axes as well as by adsorbing the ceramic substrates. The loader / unloader unit consists of the magazine up / down part, X-axis drive part for conveying the substrates to the left and right direction, and the vision part for detecting the edge of the substrate for the primary pre-alignment of the substrates. In this paper, the laser scribing machining simulation is performed by applying the instrument mechanism of each component module. Through this study, the scribing machining process is first verified by analyzing the process operation and work area of each module in advance. In addition, the scribing machining process is optimized by comparing and analyzing the scribing cycle time of one ceramic substrate according to the alignment stage module speed.

• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.3-6
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• 2008

Electrical discharge machining (EDM) is one of the most widespread nonconventional machining processes. Recently, a low-power micro-EDM process was introduced using a cylindrical electrode. Since its development, micro-EDM has been applied effectively to micromachining, and because the device setup for this process is simple, it is suitable for a microfactory that minimizes machines to fabricate small products economically in one system. In the EDM process, however, the electrode is also removed along with the workpiece. Therefore, the electrode shape and length vary as machining progresses. In this paper, a control method using a high speed realtime voltage measurement is proposed to regulate the rate and amount of material removed. The proposed method is based on the assumption that the volume of the workpiece removed in a single discharge pulses is nearly constant. The discharge pulses are monitored and controlled to regulate the amount of material removed. For this purpose, we developed an algorithm and apparatus for counting the number of discharge pulses. Electrode wear compensation using pulse number information was applied to EDM milling in a microfactory, in which a slight tilt of the workpiece may occur. The proposed control method improves the machining quality and efficiency by eliminating the inaccuracies caused by electrode wear and workpiece tilt.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.401-402
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• 2006

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.158-161
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• 2003

Recently, the evolution in production techniques (e.g. high-speed milling), the complex shapes involved in modem production design, and the ever increasing pressure for higher productivity demand a drastic improvement of the dynamic behavior of the machine tool axes used in production machinery. And also machine tools of multi functional and minimized parts are increasingly required as demand of higher accurate in some fields such as electronic and optical components etc. The accuracy and the productivity of machined parts are natural to depend on the linear system of machine tools. The complex workpiece surfaces encountered in present-day products and generated by CAD systems are to be transformed into tool paths for machine tools. The more complex these tool paths and the higher the speed requirements, the higher the acceleration requirements are needed to the machine tool axes and the motion control system, and the more difficult it is to meet the requirements. The traditional indirect drive design for high speed machine tools, which consists of a rotary motor with a ball-screw transmission to the slide, is limited in speed, acceleration, and accuracy. The direct drive design of machine tool axes. which is based on linear motors and which recently appeared on the market. is a viable candidate to meet the ever increasing demands, because of these advantages such as no backlash, less friction, no mechanical limitations on acceleration and velocity and mechanical simplicity. Therefore performance tests were carried out to machine tool axes based on linear motor. Especially, dynamic characteristics were investigated through circular test.