• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.206-207
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• 2005

The gradient of the residual stress distribution in the mechanical defect on the optical fiber surface was investigated. This gradient of the residual stress distribution appeared in both of the core and the clad of the mechanical defect region on the optical fiber. The residual stress measurement was suggested as a investigation method of the mechanical defect on the optical fiber.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1055-1056
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.233-236
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• 1997

In modem industry, the accuracy and the surface-finish requirements for machined parts have been becoming ever more stringent. Optical method in measurements is playing an important role in vibration measurement, crack and defect detection and surface topography with the advent of opto-mechatronics. In this study, the principle of the general confocal microscope is introduced for surface measurement, and the advanced confocal microscope that has better measuring speed than the traditional confocal microscope is developed. A study on improving the resolution of the advanced confocal microscope is followed. Finally, Software for data acquisition and analysis of various parameters in surface geometrical features has been developed.

• 비파괴검사학회지
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• 제25권3호
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• pp.215-221
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• 2005

It is required to evaluate nondestructively depth of surface-breaking cracks in structures. In this paper, the self-compensated technique by laser-based ultrasound is used to measure the depth of surface-breaking defect. Optical generation of ultrasound produces a well defined pulse with reliable frequency content. It is broad banded and suitable for measurement of attenuation and scattering over a wide frequency range. The self-calibrated signal transmission data of surface wave shows good sensitivity as a practical tool far assessment of surface-breaking defect depth. It is suggested that the relationship between the signal transmission and crack depth can be used to predict the surface-breaking crack depths in structures.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.36-39
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• 2000

A small electrical potential difference which appears on any solid body when subjected to illumination by a modulated light beam generated by laser is called photocharge voltage(PCV)[1,2]. This voltage is proportional to the induced change in the surface electrical charge and is capacitatively measured on various materials such as conductors, semiconductors, ceramics, dielectrics and biological objects. The amplitude of the detected signal depends on the type of material under investigation, and on the surface properties of the sample. In photocharge voltage spectroscopy measurements[3], the sample is illuminated by both a steady state monochromatic bias light and the pulsed laser. The monochromatic light is used to created a variation in the steady state population of trap levels in the surface and space charge region of semiconductor samples which does result in a change in the measured voltage. Using this technique the spatial variation of PCV can be utilized to evaluate the surface conditions of the sample and the variation of the PCV due to the monochromatic bias light are utilized to characterize the surface states. A qualitative analysis of the proposed measurement is present along with experimental results performed on amorphous silicon samples. The deposition temperature was varied in order to obtain samples with different structural, optical and electronic properties and measurements are related to the defect density in amorphous thin film.

• 한국정밀공학회지
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• 제29권1호
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• pp.48-55
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• 2012

Pressure vessels in vehicle industries, power plants, and chemical industries are often affected by flaw and defect generated inside the pressure vessels due to production processes or being used. It is very important to detect such internal defects of pressure vessel because they sometimes bring out serious problems. In this paper, an optical defect detection method using digital shearography is used. This method has advantages that the inspection can be performed at a real time measurement and is less sensitive to environmental noise. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). The ultimate goal of this paper is to detect flaws in pressure vessels and to measure the lengths of the flaws by using unwrapping, phase images which are only obtained by Phase map. Through this method, we could decrease post-processing (next processing). Real length of a pixel can be calculated by comparing minimum and maximum unwrapping images with shearing angle. Through measuring several specimen defects which have different lengths and depths of defect, it can be possible to interpret quantitatively by calculating gray level.

• Archives of Plastic Surgery
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• 제35권6호
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• pp.755-758
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• 2008

Purpose: In order to determine the amount of wound healing, objective sequential assessments of changes in wound size and depth are essential. Although a variety of measurements for wound healing have been proposed, a gold standard for quantifying day-to-day changes in healing has not been established. We present here a simple and non-invasive wound measurement method that quantitatively and accurately documents changes of the size of a raw surface and the volume of a soft tissue defect using a stereoimage optical topometer(SOT) system. Methods: Using a 5mm diameter biopsy punch, four circular wounds were created on abdominal area of a diabetic mouse. Photographs were taken using SOT system at baseline, 5th day and 10th postoperative day. The wound margin was traced on a digitalized photo and evaluated the area and the volume of the wound by SOT system. Results: The SOT system calculated a mean wound surface of $15.93{\pm}0.29mm^2$ and volume of $827.50{\pm}88.86$ intensity/pixel${\times}$area(I/PA) immediately after wounding. On the 5th day after the operation wound surface declined by $10.73mm^2$ and on the 10th day declined by $5.95mm^2$. The wound volume also declined from 827.50 I/PA to 161.75 I/PA and 30.50 I/PA on 0, 5th and 10th day, respectively. Conclusion: The SOT system described in this study represents a reliable, simple, practical, and non-invasive technique to accurately monitor and evaluate wound healing.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.36-39
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• 2000

A small electrical potential difference which appears on any solid body when subjected to illumination by a modulated light beam generated by laser is called photocharge voltage(PCV)[1,2]. This voltage is proportional to the induced change in the surface electrical charge and is capacitatively measured on various materials such as conductors, semiconductors, ceramics, dielectrics and biological objects. The amplitude of the detected signal depends on the type of material under investigation, and on the surface properties of the sample. In photocharge voltage spectroscopy measurements[3], the sample is illuminated by both a steady state monochromatic bias light and the pulsed laser. The monochromatic light is used to created a variation in the steady state population of trap levels in the surface and space charge region of semiconductor samples which does result in a change in the measured voltage. Using this technique the spatial variation of PCV can be utilized to evalulate the surface conditions of the sample and the variation of the PCV due to the monochromatic bias light are utilized to charactrize the surface states. A qualitative analysis of the proposed measuremen is present along with experimental results performed on amorphous silicon samples. The deposition temperature was varied in order to obtain samples with different structural, optical and electronic properties and measurements are related to the defect density in amorphous thin film.

• 한국항해학회지
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• 제22권4호
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• pp.59-67
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• 1998

A quick and automatic detection with no harm to the goods is very important task for improving quality control, process control and labour reduction. In real fields of industry, defect detection is mostly accomplished by skillful workers. A narrow band eliminating spatial filter having characteristics of removing the specified spatial frequency is developed by the author, and it is proved that the filter has an excellent ability for on-line and real time detection of surface defect. By the way,. this spatial filter shows a ripple phenominum in filtering characteristics. So, it is necessary to remove the ripple component for the improvement of filter gain, moreover efficiency of defect detection. The spatial filtering method has a remarkable feature which means that it is able to set up weighting function for its own sake, and which can to obtain the best signal relating to the purpose of the measurement. Hence, having an eye on such feature, theoretical analysis is carried out at first for optimal design of narrow band eliminating spatial filter, and secondly, on the basis of above results spatial filter is manufactured, and finally advanced effectiveness of spatial filter is evaluated experimentally.

• 비파괴검사학회지
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• 제21권2호
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• pp.169-176
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• 2001

근대 산업에서 기계 부품들의 정밀도와 표면 마무리 조건은 그 어느 때보다 더 절박하게 요구되고 있는 가운데, 표면 형상의 측정과 이해는 공학 기술자뿐만 아니라 물리학자나 화학자도 논은 관심을 갖게 되었다. 이런 상황에서 광학적 측정 방법은 opto-mechatronics의 이점을 가지고 진동 측정이나 균열, 결함의 검출 등의 분야에서 유용한 측정 방법으로 사용되고 있고, 표면 형상학의 분야에서 다시 한 번 중요한 역할을 할 것으로 기대를 받고 있다. 본 연구에서는 공초점 현미경의 원리에 대해 서술하였고, 기존의 스캔 방식 공초점 현미경보다 한 차원 개선된 3차원 표면형상 측정 시스템을 개발하였다. 그리고, 표면의 기하적인 형상에 대한 정보를 얻고 그 형상을 가시화하기 위해 컴퓨터 시스템과 통합하고 그에 필요한 소프트웨어를 개발하였다.