• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.75-80
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• 2000

Although laser interferometer is widely accepted as a tool for measurement of motion accuracy the set-up procedure is time-consuming because of the strict requirement on alignment between laser head and optic units. This paper presents a 4-axis auto-aligning system which is useful for easy set-up of laser interferometer so as to evaluate precision of a 2-axis feeding system. This paper proposes two ideas for alignment in laser interferometer set-up: one is use of mirror and retroreflectors. and the other is taking advantage of the pre-defined movement and peculiar characteristic of retroreflecotrs. The pros and cons of the two methods are discussed. Illustrative experimental results are presented in which the developed system is applied to a XY table.

• Laser Solutions
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• v.11 no.4
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• pp.13-20
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• 2008

The damage threshold measurement of gold films is carried out with ultrashort-pulse laser. An enhanced two temperature model is developed to encounter the limitation of linear modeling during ultrashort pulse laser ablation. In which the electron heat capacity is calculated using a quantum mechanical approach based on a Fermi-Dirac distribution, temperature-dependent electron thermal conductivity valid beyond the Fermi temperature is adopted, and reflectivity and absorption coefficient are estimated by applying a temperature-dependent electron relaxation time. The predicted damage threshold using the proposed enhanced modelclosely agreed with experimental results, demonstrating the importance of considering transient thermal and optical properties in the modeling of ultrashort pulse laser ablation.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.749-756
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• 2013

This paper presents an algorithm concerning the ground altitude measurement using a laser altimeter and an ultrasonic rangefinder for UAV(Unmanned Aerial Vehicle). A simple ground test conducted using the laser altimeter and ultrasonic rangefinder that are used for conducting the low altitude measurement of UAV and identify the characteristics of each sensor. Especially, the disadvantages of the laser altimeter were checked through the ground test. After that who those are participated in this paper planned the algorithm which is complemented by the ultrasonic rangefinder and the experiment was conducted. The laser altimeter and the ultrasonic rangefinder were fused by a loosely coupled method by Kalman filter. The paper shows that stable value of altitude complemented by the ultrasonic rangefinder that covers the laser altimeter's drawbacks can be measured through the ground test.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2003.05a
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• pp.103-106
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• 2003

• Proceedings of the Korean Society of Laser Processing Conference
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• 2001.11a
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• pp.55-59
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• 2001

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.103-103
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• 2003

A newly developed contact angle measurement instrument by laser beam projection allows for rapid and direct determination of contact angles. From the result of comparative experiment and questionnaire, the laser contact angle.

• Journal of the Korean Society of Safety
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• v.5 no.2
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• pp.50-57
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• 1990

A new technique for the measurement of surface roughness based on the intensity fluctuations of laser light backscattered from a moving surface has been introduced. This paper reports a method of measuring surface roughness using coherent optics and interferometry. Included are both the theory of the technique and experimental verification. The range of surface roughness which can be accurately measured by this method is also reported.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1076-1078
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• 1996

According to ascending needs for quality assurance of plate by customer and automated measurement of dimension for slab, in plate mill, project is on preceeding to install measuring system to measure width, length and camber of slab and plate using laser distance meter. In this document, I will describe not technical point of view but idea of design for installation system.

• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.58-65
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• 1991

In - process measurement of surface roughness is introduced which employs an optical method by using laser beam. This makes it possible to detect the surface roughness not only along the circurnferential path but also along the feed direction even during machining. The maximum roughness value is always abtainable from the reading along the feed direction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.254-259
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• 1994

Recently, the precision ball screw becomes the essence of the high-precision industries and is playing a key role in the positioning devices. The standard and definition of pitch error in a precision ball screw is specified by KS, JIS or ISO. However, the method of measuring the pitch error is not concrete. In this study. laser measurement system(LMS) with a laser position transducer and a machine-tools is developed. In order to verify the stability of the LMS, several experiments with the standard ball screw is performed.