• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.163-169
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• 2005

Micro hole is ode of basic elements for micro device or micro parts. Micro electrochemical machining (ECM) can be applied to the machining of micro holes less than 50 ${\mu}m$ in diameter, which it is not easy to apply other techniques to. For the machining of passivating metals such as stainless steel, machining conditions should be chosen carefully to prevent a passive layer. The machining conditions also affect the machining resolution, In this paper, machining characteristics of micro ECM were investigated according to machining conditions such as electrolyte concentration and pulse conditions. From the investigation, optimal machining conditions were suggested for micro ECM of stainless steel.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.30-38
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• 2003

High-speed machining is one of the most effective technology to enhance productivity especially for hardened die material. High-speed machining can give great advantages for machining of dies and molds. But selection of machining condition is very difficult because of complicated machining mechanism. This paper presents the selection of machining condition in high-speed machining of STD11. Depth of cut, feed rate and spindle revolution are control factors. The effect of the control factors on surface roughness and machining error in Z-direction is discussed to improve machining accuracy.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.63-68
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• 2018

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.205-206
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• 2010

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.89-94
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• 2002

Increasing demands on precision machining using CNC machines have necessitated that the tool to move with a position error as small as possible in 3-dimensional (3D) space. This paper presents the simultaneous 3D machining with a retrofitted PC-NC milling machine. To achieve the simultaneous 3-axis motions, a new precision interpolation algorithm for 3D Non-Uniform Rational B-Spline(NURBS) curve is used. With this accurate and efficient algorithm for the generation of complex. 3D shapes, a real-time NURBS interpolator was developed using a PC and the simultaneous 3D machining is accomplished.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.529-532
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• 2003

Machining technique for optical crystals with single point diamond turning tool is reported in this paper. The main factors influencing the machined surface quality are discovered and regularities of machining process are drawn. Optical crystals have found more and more important applications in the field of modern optics. Optical crystals are mostly brittle materials of poor machinability. The traditional machining method is polishing which has many shortcomings such as low production efficiency. poor ability to be automatically controlled and edge effect of the workpiece. The purpose of our research is to find the optimum machining conditions for ductile cutting of optical crystals and apply the SPDT technique to the manufacturing of ultra precision optical components of brittle materials. As a result. the surface roughness is good when spindle speed is 200m/min. and teed rate is small. The influence of depth of cut is very small.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.81-86
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• 2006

The machining parts must be produced within the specification of drawing and those will be able to meet function and efficiency. At that time, it is very important not only precision machine and machining technique but also the measurement technique. So, the improvement of measurement technique is to be joined together at once with improvement of machining technique. Finally, the quality and value of the parts are decided by precision measurement. This paper aims to study on the machined surfaces characteristics of aluminum alloy by AFM(Atomic force microscope) measurement. The objective is contribution to ultra-precision machining by exhibit foundation data of surface roughness and tool wear when parts are cutting with diamond tool at the factory.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.17-24
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• 2001

Recently, the requirements for high precision and efficiency machining are gradually increased to raise international competitiveness at the industrial fields of die and molds. This trend had made effects on the industrial fields in Korea and which needs fur studying of high precision and efficiency machining. This study is to investigate the effects of the non-out of end mill in the external cylindrical machining operated by solid carbide end mills with Al-alloy in high speed machining center relating to high spindle revolution and frost fred per minute on the dimensional precision, roundness of workpiece. From the results of experimentations followings are obtained; when Al-alloy is processed by the external cylindrical cutting of end milling through the high speed revolution, if the spindle revolution is higher relating to radial depth of cut, feed per tooth in very lower situation, finally, productivity can be raised because high precision and quality products are machined high efficiently.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.158-161
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• 2005

In this paper, the precision electric discharge machining technology, the powder electric discharge machining technology, is applied to making a cold forging die for making the helical type of clutch gear. Various working conditions are investigated with emphasis on reduction of the electrode wear and enhancement of the surface roughness. Through the research work, the key technology of making the helical gear forging dies is achieved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.94-99
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• 2005

Though the technology on the ultra-precise machining has been developed intensively, the high speed and high precision for large machining range is still very hard to achieve. The linear motor system fur the universal machining center is proper fur high speed and high precision, but it has drawback of sensitivity to disturbance. In this research, two degrees of freedom controller based on the zero phase error tracking controller (ZPETC) and disturbance observer are proposed to improve the tracking performance and dynamic stiffness of linear motor system. The proposed controller is verified in simulations and experiments on a nano-positioner system, and the experimental result shows that the tracking performance improved. In addition, the PID optimization method is proposed for the commercialized controller such as the PMAC based system. The tracking as well as impedance is included in the cost function of optimization.