• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.5-12
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• 2010

A novel algorithm which computes the orientations and the locations of mobile robots with repeating feature of ceiling textures is proposed. For orientation computation, the relative angle between a strait line on a ceiling image and the center line of the robot is firstly computed. The relative angle is added to the global reference angles of straight lines of the ceiling and a group of robot orientation candidates is composed. The robot orientation is determined from such orientation candidate group by choosing the closest one to the previous robot orientation. Similarly, the location of the robot is determined from the robot location candidate group by choosing the closest one to the previous robot location, where robot location candidate group is composed by adding the relative location of the robot to global locations of neighboring nodes of the previous robot locations. The experiment has been done to test the accuracy of the algorithm in computing locations and orientations.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.232-238
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• 2000

The new collimation testing technique of a white light beam using vernier Moire fringes of two line or circular gratings with different pitches is presented. We can visually measure the defocusing ($\Deltaf$), the divergence angle ($\theta$), and the longitudinal chromatic aberration $(L_{ch})$ of a collimating lens by using the technique. For example, we obtained $\Deltaf$= 21.9 mm and $\theta=0.0038^{\circ}$ for a testing lens with the focallengthf = 120.0 mm and F-number of F/2.4. The longitudinal chromatic aberration $L_{ch}$ of another testing lens withf = 65.0 mm, F/1.6, and the Abbe number V = 64.1 for the incident wavelengths of $\lambda_1=480 nm and \lambda_2=640 nm$ is easily measured by same technique. It is found that the measured value $L_{ch}=1.59mm(\pm0.01mm)$ is well agreed with $L_{ch}=1.58mm(\pm0.01mm)$ obtained by the autofocus method.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.182-188
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• 2002

We have analyzed the phase-calculation-error of a three-dimensional shape measurement system using the projection of phase shifted fringe patterns. In this study, we have dealt various errors; an error caused by the variation of quantization levels, an error caused by the defocus of fringe pattern projected images, an error caused by phase-shifting errors, an error caused by the intensity variation of the background and modulation amplitude of fringe pattern projected images during the projection of multiple patterns, an error caused by the distortion of sinusoidal shape of a fringe pattern. The results will contribute to the design of a three-dimensional shape measurment system and give an important meaning to the calculation and the analysis of the accuracy of a system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.170-175
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• 1999

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and its's high sensitivity. Especially, when projecting a grid pattern over the object the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, new method for grid pattern generation system by polygonal mirror and Laser Diode. This system is applied the projection moire and the PMP.

• Proceedings of the Korean Vacuum Society Conference
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• 1993.07a
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• pp.95-95
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• 1993

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.157-158
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• 2006

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.328-334
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• 1999

Methylene blue-sensitized photopolymerizable material based on acrylamide is investigated with two-wave energy coupling experiments. Differently from other studies, self-diffraction oscillations are observed and the grating phase is determined without applying external electric fields, moving nonlinear materials, and phase shifting one of two writing beams. The phase grating showed a phase shift of $\pm$50$^{\circ}$ with respect to the intensity grating. Modified Kogelnik's coupled wave equation considering the mixed gratings of phase and absorption gratings and nonzero spatial phase shifts of the gratings with respect to the intensity interference patterns formed during the two-wave energy coupling is discussed in detail to understand these phenomenon.

• Journal of the Korea Fashion and Costume Design Association
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• v.6 no.2
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• pp.15-20
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• 2004

These days are referred to as 'the times of textile fashion,' owing to the emphasis on textile design in the fashion industry. Accordingly, apparel companies have increased their interests in developing new types of textiles to overcome the limits of style and silhouette. Now the ultra-fashion of textile, a new way of process and design development, is given much more attention. A Moire interference pattern has a longer wavy circle of interference, an effect of intensity interference, than one made by piling more than one reflecting plate or transmitting plate. Till now, Moire interference patterns have been used to confirm scientific theory and to measure the structure of a body or a subject in areas such as physics and medical science. Work has also been done on the Moire interference effects on TV screens said to cause dizziness and eye strain. This study focuses on the new types of textiles by creating the appearance of the Moire phenomena. Contrary to the present usual stationary patterns of textiles, it is a varying pattern according to the different gratings, different angles, piling gratings, and the movements of the human bodies. In the preceding study, we observed Moire fringes formed by overlapping two different or same kinds of gratings such as parallel line gratings, square gratings, conic gratings and semicircular gratings and tried to find a promising possibility of new textiles through the method of clothes design simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.181-181
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• 2004

3 차원 형상측정기술(3-D Profile Measurement Method)은 가공품의 치수검사 및 형상측정 등의 공학분야뿐만 아니라 최근에는 의류산업 및 의학산업은 물론 오락산업의 가상현실 구현 등 여러 분야로 점차 사용이 확대되고 있다. 이러한 요구를 만족시킬 수 있는 광학을 바탕으로 한 비접촉 3 차원 형상측정방법(Non-contacting 3-D Profile Measuring Method)은 고속, 고정밀도 측정이 가능하기 때문에 활발히 연구되고 있다. 광학을 이용한 대표적인 3 차원 비접촉 측정방법의 하나인 영사식 무아레는 그림자식 무아레의 단점인 격자의 크기가 측정물체보다 커야 한다는 점과 측정물체와 격자사이의 거리 제한 문제를 해결하였으며, 위상이동법을 사용함으로서, 무아레 무늬 형태의 영향을 받지 않고 측정이 가능해졌다.(중략)

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.56-62
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• 2004

We present a diffraction grating interferometer of large equivalent wavelength specially designed for flatness testing of rough surfaces. Two transmission diffraction gratings are illuminated on the object under test by use of two measurement beams with different angles of incidence, which yields a large equivalent wavelength. This interferometer design minimizes unnecessary diffraction rays and the systematic error caused by the diffraction gratings, and provides a large working distance and easy alignment. To improve the measurement accuracy, phase shifting technique is applied and the equivalent wavelength error caused by defocus is calibrated. Test results obtained from mirror surfaces and machined rough surfaces are discussed.