• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1767_1768
• /
• 2009

4-step 알고리즘을 이용하여 3차원 이미지 위상 정보를 분석하였다. Carre(1966)에 의하여 제시된 위상 분석 기술은 위상이동에 대하여 설명하고 있다. Wyant(1982)에 의한 4-step 알고리즘은 수많은 PSI(Phase-Shift Interferometry)법[1] 중에서 가장 일반적인 내용이다. 그러나 실험장비 설치 시, 매우 어렵다는 단점이 있다. 실험 과정에서 물체의 3차원 형상을 얻기 위해 매우 간단히 실험 설치를 하였다. 간섭 패턴은 추가적인 렌즈, 거울, 모터와 같은 광학장비 없이 랩뷰 프로그램과 비젼 시스템을 사용하여 구축하였다. 4-step method와 컴퓨터 프로그램에 의해 생성된 unwrapping image에 의해 물체의 wrapped된 이미지를 얻었다. 실험에 의하여 얻어진 간섭패턴을 분석 함으로써, 웨이브 프론트, 강도 그래프, 3차원 형상, 상수 데이터와 같은 다양한 정보를 얻을 수 있었다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.04a
• /
• pp.491-494
• /
• 2004

Neural Oscillator can be applied to oscillatory systems such as the image recognition, the voice recognition, estimate of the weather fluctuation and analysis of geological fluctuation etc in nature and principally, it is used often to pattern recoglition of image information. Conventional BPL(Back-Propagation Learning) and MLNN(Multi Layer Neural Network) are not proper for oscillatory systems because these algorithm complicate Learning structure, have tedious procedures and sluggish convergence problem. However, these problems can be easily solved by using a synchrony characteristic of neural oscillator with PLL(phase-Locked Loop) function and by using a simple Hebbian learning rule. And also, Recognition velocity of Korean Character can be improved by using a Neural Oscillator's learning accelerator factor η$\_$ij/

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.315-317
• /
• 2003

Neural oscillator is applied in oscillatory systems (Analysis of image information, Voice recognition. Etc...). If we apply established EBPA(Error back Propagation Algorithm) to oscillatory system, we are difficult to presume complicated input's patterns. Therefore, it requires more data at training, and approximation of convergent speed is difficult. In this paper, I studied the neural oscillator as synchronized states with appropriate phase relation between neurons and recognized the Korean alphabet using Neural Oscillator Phase model Synchronization.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.7 no.3
• /
• pp.8-14
• /
• 2011

The clogging of the flow area at the tube support plates(TSPs), especially at the upper TSPs results in the water level oscillation of a steam generator during normal operation. A reduction of the TSP flow area causes to increase in pressure drop within the two-phase flow zone, which destabilizes the boiling flow through the tube bundle. This phenomenon was occasionally observed at a few domestic and foreign nuclear power plants. One of the methods for defining the flow area clogging is visual inspection, which is the most effective inspection method. The results of the visual inspection for TSPs' flow area are clogging images on TSPs' quartrefoil lobes. These images are complexly distorted due to lens aberration and external factors like the distance to a subject and angle etc. In this work, we developed the analysis algorithm for clogging image of the TSP flow area of steam generators. For this purpose, we designed an image verification device applicable to the camera employed in the field for visual inspection and then, we demonstrated the validity of image analysis algorithm by using this device and commercial autoCAD program.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.291-292
• /
• 2006

A steel/cemented carbide couple is selected to generate a tough/hard two layers material. Sintering temperature and composition are deduced from phase equilibria, and experimental studies are used to determine optimal conditions. Liquid migration from the hard layer to the tough one is observed. Microstructure evolution during sintering of the tough material (TEM, SEM, image analysis) evidences coupled mechanisms of pore reduction and WC dissolution. Liquid migration, as well as interface crack formation due to differential densification are limited by suitable temperature and time conditions.

• Current Optics and Photonics
• /
• v.8 no.3
• /
• pp.259-269
• /
• 2024

Optical imaging systems that operate through atmospheric pathways often suffer from image degradation, mainly caused by the distortion of light waves due to turbulence in the atmosphere. Adaptive optics technology can be used to correct the image distortion caused by atmospheric disturbances. However, there are challenges in conducting experiments with strong atmospheric conditions. An optical phase plate (OPP) is a device that can simulate real atmospheric conditions in a lab setting. We suggest a novel two-step process to fabricate an OPP capable of simulating the effects of atmospheric turbulence. The proposed fabrication method simplifies the process by eliminating additional activities such as phase-screen design and phase simulation. This enables an efficient and economical fabrication of the OPP. We conducted our analysis using the statistical fluctuations of the refractive index and applied modal expansion using Kolmogorov's theory. The experiment aims to fabricate an OPP with parameters D/r₀ ≈ 30 and r₀ ≈ 5 cm. The objective is defined with the strong atmospheric conditions. Finally, we have fabricated an OPP that satisfied the desired objectives. The OPP closely simulate turbulence to real atmospheric conditions.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.11
• /
• pp.43-51
• /
• 2004

In this paper, we propose a high-level optical encryption system, which is tolerant with noises and cropping, by encrypting the phase-encoded CGH pattern of original image with the phase-encoded Fresnel diffraction pattern of random key images. For encryption, the phase-encoded CGH pattern of original image is multiplied by conjugate components which are the phase-encoded Fresnel diffraction patterns of random key images. The original information can be reconstructed by multiplying encrypted image by phase-encoded Fresnel diffraction pattern of random key images and performing Fourier transform of the multiplication result. The proposed system is robust to noises and cropping due to characteristics of CGH pattern and can guarantee high-level encryption by using Fresnel diffraction information. We verified the validity of proposed system by computer simulations, numerical analysis of noises and cropping effect and optical experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.421-424
• /
• 2002

The 3-D measurement using a sinusoidal grating pattern projection is very attractive because of its high measuring speed and high sensitivity. When a sinusoidal amplitude grating was projected on an object, the surface-height distribution of the object is translated into a phase distribution of the deformed grating image. The phase-acquisition algorithms are so sufficiently simple that high-resolution phase maps using a CCD camera can be generated in a short time. The PMP technique is discussed, and the analysis of the systematic errors, the calibration procedure designed to determined the optimal setting of the measurement parameters is illustrated. Results of measurements and calibrations on the measurement plane objects are described.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.9 s.180
• /
• pp.2313-2318
• /
• 2000

The method of photoelasticity allows one to obtain principal stress differences and principal stress directions in a photoelastic model. In the classical approach, the photoelastic parameters are measured manually point by point. This is time consuming and requires skill in the identification and measurement of photoelastic data. Fringe phase shifting method has been recently developed and widely used to measure and analyze fringe data in photo-mechanics. This paper presents the test results of photoelastic fringe phase shifting method for the stress analysis of a curved beam plate. The technique used here requires four phase stepped photoelastic images obtained from a circular polariscope by rotating the analyzer at 0˚, 45˚, 90˚ and 135˚. Experimental results are compared with those of ANSYS and calculated by the simple beam theory. Good agreement among the results can be observed.

• KSTLE International Journal
• /
• v.1 no.2
• /
• pp.69-75
• /
• 2000

The paper compares topography, phase contrast and force spectroscopy in atomic force microscopy data for evaluating the microheterogeneity of surface layer. The worn surface of ion-plated TiN coating was measured using both a laboratory-built and a commercial AFM. The results of analysis revealed structural and micromechanical heterogeneity of the worn surfaces. We demonstrated that the phase image allows relatively qualitative estimation of elastic modulus of the sample surface. The tribolayer formed in the worn surface possessed much lower stiffness than the original coating. It is shown that the most stable phase imaging is provided with a stiff cantilever. In this case, phase contrast is well conditioned, first of all, by microheterogeneity of elastic properties of the investigated surfaces. In this study an attempt was also made to correlate the results of phase imaging with that of the farce spectroscopy. The joint analysis of information on the surface properties obtained by the phase imaging and quantitative data measured with the force spectroscopy methods allows a better understanding of the nature of the surface micromechanical heterogeneity.