• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.293-298
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• 1998

In surface grinding, the conditions of the grinding wheel give a significant effect on the ground workpieces comparing with other metal removal processes. In this paper, to assist the development, a non-contacting optical method is introduced to make in-process measurements of scattering intensities from laser beam during surface grinding processes. This show indications of changes in surface texture of wheel working surfaces. Also, in order to determine the dressing time monitoring method of grinding wheel in surface grinding, a three-dimensional computer simulation of the grinding operation has been attempted based on the contact mechanism and surface-shaping system between the grinding wheel and the workpiece. The optical dressing time is determined based on the amount of the grain wear and work surface roughness.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.333-336
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• 2010

The generation of coherent x-ray beams by using a multi-slit diffraction phenomenon is presented. The mode-confinement conditions in the x-ray waveguide (XWG) needed to obtain single-mode beams are determined. The XWGs are stacked to form an XWG array. The core of the XWG array is used as a slit in an opaque screen, similar to those used for visible light. Diffraction patterns that interfered constructively in the XWG array are investigated based on multi-slit diffraction theory. The irradiance distributions are studied at on observation screen. The FWHM of diffracted x-ray spectra were between $1.67{\times}10^{-4}$ to $3.30{\times}10^{-5}$ radians which lead to a spot-size of a few tens of micrometers on the screen at distance of 1 m. The intensities decrease with increase in the period of the XWG array, i.e. a thicker cladding, due to growth of the higher-order diffraction peaks.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.6
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• pp.694-699
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• 1988

Optical phase conjugate mechanism and edge enhancement by degenerate four wave mixing (DFWM) in photorefractive material are described, and image reconstruction is perfromed sucessfully in BaTiO3 single crystal. Also, the edge enhancement is carried out in the crystal by the same DFWM geometry. But the intensities of three incident beams are inverted. Good quality of edge enhancement is observed in real-time (processing time 10 sec) with low incident light intensity (5.38mW/cm\ulcorner.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.10
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• pp.399-406
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• 1985

In this paper transparent PLZT ceramics for the composition of 9/65/35 (La/Zr/Ti ) are fabricated using hotpress and the possibility of application to optical shutter is examined by obtaining the On-Off characteristics of specimens. The ferroelectric E-P hysteresis loop exhibits slim loop suitable for the quadratic electrooptic effect. Measurements of the electrooptic effect show that specimens have the quadratic electrooptic effect but the light intensities as functions of electric field exhibit butterfly type hysteresis curves because of its slightly large saturation remanent polarization and coercive field. On-Off characteristics are obtained by electric fields of-6 kv/cm and +2kv/cm. As a result of experiments, 9/65/35 PLZT ceramics can be applied to optical shutter but construction with other composition which has more slim hysteresis loop is desired for obtaining the Off state by zero electric field.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.455-455
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• 2000

A novel pulse-width-modulated (PWM) function is introduced for precise position measurement in an enclosed signal field. An amplitude modulation was used to light the LEDs for the conventional study. However, the transform properties from the driving signal to the lighting intensities of the LEDs are non-linear, and accurate control of the lighting power was necessary. Therefore, a lighting function independent of these properties is desired. Well-known PWM functions are used to construct the enclosed signal field by simulation, and the precision of the phase detecting system is analyzed. A novel "axial symmetry PWM" function is found to be effective for orthogonal pahse detection.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.53-60
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• 2008

Electron detectors used in scanning electron microscope accept electrons emitted from the specimen and convert them to an electrical signal that, after amplification, is used to modulate the gray-level intensities on a cathode ray tube, producing an image of the specimen. Electron detector is one of the key components dominating the performance of scanning electron microscope so that the development of electron detectors having high performance is indispensable to acquire high quality images using scanning electron microscope. In this paper, we designed and manufactured an electron detector and conducted a couple of image capture experiments using it. In particular, scintillator which generates light photons when it is struck by high-energy electrons was manufactured and experimental studies on the optimization of manufacturing condition was carried out. From experiments to evaluate the performance of our detector, it was verified that the performance of our detector is equivalent to or better than that of the conventional one.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.160-165
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• 1999

In surface grinding, the conditions of the grinding wheel give a significant effect on the ground workpieces comparing with other metal removal provesses. In this paper, to assist the development, a non-contacting optical method by the laser beam is introduced. The in-process measurement of scattering intensities has been made during surface grinding processes and the surface textures of wheel working surfaces are captured. Also, in order to determine the dressing time monitoring method of a grinding wheel, a three-dimensional computer simulation of the grinding operation has been attempted based on the contact mechanism and the surface-shaping system between the grinding wheel and the workpiece. The optimal dressing time is determined by the amount of the grain wear and work surface roughness.

• Textile Coloration and Finishing
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• v.16 no.1
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• pp.10-17
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• 2004

Wool fabrics were treated with deep UV for 10 to 30min and then dyed with C.I. Acid Yellow 99, C.I, Acid Red 57 and C.I. Acid Blue 62. FT-IR and XPS have been used to prove the chemical composition of wool fiber surfaces. The mechanical property and colorfastness were also studied. The intencities of the peaks of C=O group at $1700^cm^{-1}$ were increased with increasing irradiation time. Relative $O_{1s},\; N_{1s}\; and\; S_{2p}$ intensities increased considerably and oxygen was incorporated in the form of CO and COO on the fiber surface. The dye uptakes of wool fabrics dyed with three acid dyes were proportional to irradiation times and in inversely proportional to irradiation distances. It was found that the tensile strength of wool fabrics were gradually deteriorated with the UV irradiation times. The colorfastness, such as washing, light and rubbing, of UV irradiated wool fabrics dyed with acid dyes were good.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.593-600
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• 1999

The structure of premixed turbulent flames in constant volume vessel was investigated by using a laser tomography. The flame structure was visualized by passing a laser sheet with 0.2mm thick and 2 cm wide through the turbulent flames to obtain their 2-D images. From the obtained images islands of reactants as well as of products were found at least in the 2-D images when the turbu-lence intensity was above 0.4m/s. Moreover in order to obtain the characteristic flamelet thickness the light intensities of them were digitized and processed into three colors incorporating two appro-priate threshold values in the image analysis. As the result the averaged value of charactertistic flamelet thickness was found to be about two times compared to laminar one.

• Analytical Science and Technology
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• v.17 no.4
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• pp.315-321
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• 2004

The aim of this study was to investigate the evidential value of blue and black ballpoint pens on paper by nondestructive techniques. In this work, 21 blue and 22 black ballpoint pens which were purchased on different brands were analyzed by Raman Spectroscopy and Video Spectral Comparator (VSC). Surface-Enhanced Resonance Raman Spectroscopy (SERRS) with excitation at 685 nm and VSC with several spot light filters were used for the discrimination of ballpoint pen inks. In the SERR spectra, the ballpoint pen inks on paper could be shown sharp spectral bands and distinguished by their band shapes and relative intensities. In the blue and black ballpoint pen inks, the discriminating powers (DP) by SERRS were 0.85 and 0.67 and the DP by VSC were 0.88 and 0.90, respectively. The DP by combined sequence of techniques was all 0.97 in both black and blue ballpoint pen inks.