• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1283-1289
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• 2013

The purpose of this study is to find the new method for estiming the spatial variations in a light source with utilizing the optical fiber sensory system. With this aim, firstly the asymmetry in the beam profile of a light source is evaluated by using the tipped optical fiber with 0, 10, 20, 30, 40, 45-degree angle. Secondly the variation of position in a light source is estimated by adjusting the relative position between the light source unit (XYZ stage, LED, Optical fiber) and the receiver unit (Photodiode, XYZ stage). Our experimental results show that the spatial variation of a light source can be resolved in terms of the variations in beam profile with varying the tip angle of an optical fiber and adjusting the relative distance between the light source unit and the receiver.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.130-137
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• 2015

This paper presents the development process of automotive side door impact beam for passenger cars. Weight reduction while maintaining functional requirements is one of the major goals in the automotive industry. In this study, thin-walled side door beam using quenchable boron steel was designed to reduce the weight of conventional side door tubular one. In order to estimate design for the proposed side door beams, the static side impact protection tests(FMVSS 214) were conducted using the finite element method. Based on the simulation results, geometry modification of the side door beam has been performed via creating new reinforcing ribs. Furthermore, the manufactured frontal impact beam was mounted on the real side door of a passenger car, and then static impact protection test carried out. It is concluded that the presented test results can provide significant contribution to the stiffness of side door impact beams and light-weighting door research.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.64-71
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• 2005

In order to measure surface roughness profile, stylus type equipments are commonly used, but the stylus keeps contact with surface and damages specimens by its tip pressure. Therefore, optics based measurement systems are developed, and light phase interferometer, which is based on light interference phenomenon, is the most noticeable research. However, light interference based measurements require translation mechanisms of nano-meter order in order to generate phase differences or multiple focusing, thus the systems cannot satisfy the industrial need of on-the-machine and in-process measurement to achieve factory automation and productive enhancement. In this research, we focused light reflectance phenomenon rather than the light interference, because reflectance based method do not need translation mechanisms. However, the method cannot direct]y measure surface roughness profile, because reflected light consists of several components and thus it cannot supply surface height information with its original form. In order to overcome the demerit, we newly proposed an image processing based algorithm, which can separate reflected light components and conduct parameterization and reconstruction process with respect to surface height information, and then confirmed the reliability of proposed algorithm by experiment.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.94-101
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• 2004

From the Beckmann's reflection model of wave incident, reflected light from a surface is known to have not only specular but also diffuse components. The specular component dominant a surface for a mirror-like surface is distributed on the almost the same area as the spot on the surface, but the diffuse component region dominant f3r a rough surface spreads scattered on the larger areas than the spot. Therefore, statistic parameters from the scattered light distribution are more meaningful in the diffuse region, while the magnitude of rather meaning in the specular region. In usual, there need two sensors to acquire two kinds of information: Photo-detector for light intensity magnitude and image sensor for light intensity distribution. But dual sensor scheme requires a beam splitter usually to feed light to each sensor, and moreover there is not a combination rule to relieve the different sensor characteristics. In this study a new method is proposed for acquisition of the dual information using only an image sensor. Specular region is established on an image area being distinguished from a diffuse component, and laser power is adjusted so that no pixel of the image sensor in the specular region is saturated. Simulation based on the light reflection theory and the experimental results are quite well matched, and thus the proposed method was proved to be very useful for mirror-like surface measurement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.683-684
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.829-830
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• 2010

• Proceedings of the Korean Vacuum Society Conference
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• 1993.07a
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• pp.39-39
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• 1993

A finite element analysis and Monte Carlo method have been applied to calculate the ppressure pprofiles around the ppohang Light Source (ppLS) electron storage ring with the aim of ppredicting the pperformance of the vacuum system designed for the ppLS vacuum system. After ppropperly choosing the design pparameters, the ppressure distribution are calculated as a function of the integrated stored beam current [AmppHrs]. The effect of changes of the vacuum pparameters, such as installed ppumpping sppeeds and synchrotron radiation induced gas desorpption rates on the ppressure pprofile, is also studied. The results indicate that the use of lumpped non-evapporable getter ppumpps together with spputter ion ppumpps for ppumpping the ppLS down to the required ppressure is ppossible in the ppresence of synchrotron induced gas loads, after resonable beam cleaning time.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.486-490
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• 2013

A portable infrared laser transmitter delivering a highly uniform detectable beam was demonstrated. It incorporates a flexible beam shaper, comprising a perforated diffuser sheet in conjunction with a pinhole. The beam shaper plays the prominent role of flexibly tailoring the incoming light via both scattering and diffraction, in order to equalize the effective beam width over a long distance. The intensity profile of a generated beam was practically observed, demonstrating that a substantially uniform beam of 70-cm width was achieved for a given threshold detection level, with an average deviation of 6% over a range of 600 m.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.199-207
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• 2003

The Timoshenko beam model has been known as the most accurate model for representing beam structures. However, the Timoshenko beam model may give rise to a significant error when it is applied to multi-stepped beam structures. This paper is intended to demonstrate the modeling error of Timoshenko beam based finite element model for multi-stepped beam structures and to suggest a new modeling method to improve the accuracy. A tentative bending spring is introduced into the stepped section to represent the softening effect due to the presence of step. This paper also proposes a finite element modeling method in the light with the tentative bending spring model for the step softening effect. The proposed method rigorously adapts computation results from a commercial finite element code. The validity of the proposed method is demonstrated through a series of simulation and experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.295-295
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• 2008