• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.213-218
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• 2004

As optical fiber communication grows, the fiber alignment become the focus of industrial attention. This greatly influence the overall production rates for the opto-electric products. We proposed multi-axis nano positioning stage for optical fiber alignment. This device has 3 DOF translation and sub nanometer resolution. This nano stage consist of 3 PZT-driven flexure stages which are stacked parallel. The displacement of it is measured with capacitance gauge and is controlled by computer-embedded main controller. The design process of flexure stage using FEM is proposed and the performance evaluation of this system is verified with experiments.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.767-772
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• 2011

The thermal deformation of machine tool spindle influences the performance of the manufacturing systems for precision products. According to previous studies, major factors that will affect the stiffness of the spindle include spindle diameter, elasticity of the material, bearing stiffness and bearing span. It is difficult to change spindle diameter or elasticity of the material. but change of bearing position is easy in the given range compared to other factors. In this paper, we will find a solution to minimize thermal deformation through Change the span of the bearing.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1144-1149
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• 2008

Converting technology has developed to print information for the decades. Recently, this technology (like gravure, gravure-offset) is rising as an alternative way for mass production of printed electronics such as RFID, solar cell. For the width of printing line is under 10 microns, registration error should be minimized less than several microns. Tension disturbance is main cause of registration error and this should be minimized before the substrate is transported into printing zone. With PI controller, it is possible to suppress the disturbance within 2% of operating tension. But register error appears more than 10 micron using PIcontroller considering noise. So LQG controller is needed as an alternative control method. In this paper, the comparision of PI and LQG controller in the converting machine including measured noise and tension disturbance is presented. It is shown that the LQG controller is more suitable for precision tension control in printed electronics.

• Journal of Korea Multimedia Society
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• v.23 no.4
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• pp.595-602
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• 2020

We propose a generative probabilistic model with Dirichlet prior distribution for topic modeling and text similarity analysis. It assigns a topic and calculates text correlation between documents within a corpus. It also provides posterior probabilities that are assigned to each topic of a document based on the prior distribution in the corpus. We then present a Gibbs sampling algorithm for inference about the posterior distribution and compute text correlation among 50 abstracts from the papers published by IEEE. We also conduct a supervised learning to set a benchmark that justifies the performance of the LDA (Latent Dirichlet Allocation). The experiments show that the accuracy for topic assignment to a certain document is 76% for LDA. The results for supervised learning show the accuracy of 61%, the precision of 93% and the f1-score of 96%. A discussion for experimental results indicates a thorough justification based on probabilities, distributions, evaluation metrics and correlation coefficients with respect to topic assignment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2114-2120
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• 1997

This paper presents precision machining of sculptured surfaces with a flat end cutter as follows; tool path generation using partition machining method and elimination interference. These days many researchers are getting interested in flat end cutter having a good cutting performance as machine tool for machining sculptured surfaces. It can get low curvature surfaces and have a much better material removal rates and longer tool life. Partition machining method is the first submitted in this paper. It is a new method of tool path generation, which means the way to map surfaces under the normal vector and then to cut them partially.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.1
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• pp.47-53
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• 1992

This paper is discussing the Optimum Structural Modification by the Sensitive Analysis Method. The mokificxation for the first Mouth Open Mode of the C type structure was done by using coordinate sensitivities and thickness sensitivities. The results obtained are as follows; 1. the vibration could be minimized by reducing multiples of mode components of impact point and response point. 2. the tooling precision of the Press machine could be minimized by reducing relative vibration amplititutes between the tool and the object to be tooled. 3. the mode componets of 2 points could be identified by using the coordinate sensitivites for the C type structure. 4. the mode components of 2 points could be iodentified by using the thickness sensitivities for the C type structure.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1787-1792
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• 2003

Recently with the development of semiconductor technology, the miniaturization of parts and products as well as their high precision is required. In addition, as the national competitiveness is increasingly affected by the development of the micro parts through micro machining technology, the study of the micro machining technology is being conducted in many countries. The goal of this study is to fabricate micro tools under the size of $20{\mu}m$ and to machine micro holes using them. The fabrication is done by grinding and the application of ELID to the grinding wheel. The surface roughness of the micro tools is measured to evaluate the study.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1822-1827
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• 2003

End-milling have been used widely in industrial system because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in precision machine part and electronic part. The optimum surface roughness has an effect on end-milling condition such as, cutting direction, spindle speed, feed rate and depth of cut, etc. Therefore this study was carried out to presume for mutual relation of end-milling condition to get the optimum surface roughness by regression analysis. The results shown that coefficient of determination($R^{2}m$) of regression equation has a fine reliability over 80% and regression equation of surface rough is made by regression analysis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.1
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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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.1
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• pp.13-17
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• 2005

We explored a new rough grinding technique on optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of diamond resin bond wheel. The grinding parameters such as workpiece rotation speed, depth of cut and feed rate were altered while grinding the workpiece surfaces of 20mm in diameter. Surface roughness was measured by Form Talysurf series2. Our target is to define grinding conditions producing the surface roughness smaller than $0.2{\mu}m$ Ra.