• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.131-136
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• 2010

Modification of the phase gradient formulation is proposed in order to make phase retrieval less susceptible to noise. The modified formulation is derived from separation of the phase terms and the intensity modulation terms of interferograms, and subsequent differentiation to reduce the noise-induced error of the phase gradient vector. Its performance is evaluated and compared to that of the conventional formulation, and noise-robust nature is confirmed.

• International Journal of Control, Automation, and Systems
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• 제4권1호
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• pp.96-104
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• 2006

We propose a path planning method to improve the productivity of AOI (automated optical inspection) machines in PCB (printed circuit board) assembly lines. The path-planning problem is the optimization problem of finding inspection clusters and the visiting sequence of cameras to minimize the overall working time. A unified method is newly proposed to determine the inspection clusters and visiting sequence simultaneously. We apply a hybrid genetic algorithm to solve the highly complicated optimization problem. Comparative simulation results are presented to verify the usefulness of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.53.3-53
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• 2001

This paper deals with the development of a shape inspection system of the Light Guide Panel(LGP), and the study for the performance of the system. The conventional contact sensing methods have been used to inspect the shape. However the contact-sensing methods have some problems. The contact between a tip of the sensor and the surface of objects make a sensor tip abraded and generate a defect on the surface of objects. In this paper, we employed the Non-Contact Optical Sensor[1] to measure the shape inspection system of LGPs, The Sensor composed of Hologram laser[3] unit used for CD Optical Pickup[2] is low cost and has a good performance to measure a transparent objects. From the results of experiments for LGP shape inspection ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.109.2-109
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• 2001

In the PCB assembly lines, as components become more complex and smaller, the conventional inspection method using traditional ICT and function test show their limitations in application. The automatic optical inspection(AOI) gradually becomes the alternative in the PCB assembly line. In Particular, the PCB inspection machines need more reliable and flexible object recognition algorithms for high inspection accuracy. The conventional AOI machines use the algorithmic approaches such as template matching, Fourier analysis, edge analysis, geometric feature recognition or optical character recognition (OCR), which mostly require much of teaching time and expertise of human operators. To solve this problem, in this paper, a statistical learning based part recognition method is proposed. The performance of the ...

• Journal of Mechanical Science and Technology
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• 제16권5호
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• pp.591-598
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• 2002

Leakage magnetic flux is occurred in the cracked area of magnetized specimens, and also it changes the magnetic domain area of the magneto-optical film positioned on the specimen. It causes the change of the optical permeability of the magnetic domain on the crack area. So crack images can be obtained easily using this principle. On the other hand, utilizing a laser in this method makes possible to perform a remote sensing by detecting the light intensity contrast between cracked area and normal area. This paper shows the application of non-destructive inspection system taking advantage of magneto-optical method for micro-cracks and presents examples applied to the several types of specimens having fatigue cracks and fabricated cracks using this method. Also the authors prove the possibility of this method as a remote sensing system under the oscillation load considering application to real fields.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.173-176
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• 2002

In this paper, we present the combined 2-D and 3-D algorithms for automatic solder paste inspection. For automatic inspection, optical system for the combined inspection and driving unit is made. One-pass run length algorithm that has fast and efficient memory space is applied to the input image fur extracting solder paste patterns. The path of probe movement is then calculated for an automatic inspection. For a fast 3-D inspection, the phase shift algorithm based on Moire interferometry is also used. In addition, algorithms used in this paper are coded by $MMX^{TM}$. A probe system is manufactured to simultaneously inspect 2-D and 3-D for 10mm$\times$10mm field of view, with resolutions of 10 $\mu\textrm{m}$for both x, y axis and 17 $\mu\textrm{m}$for z axis, and then, experiments on several PCBs are conducted. The processing times of 2-D and 3-D, excluding an image capturing, is 0.039 sec and 0.047 sec, respectively. The credible result with $\pm$ 1$\mu\textrm{m}$uncertainty can be also achieved.

• 대한전자공학회논문지SP
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• 제41권3호
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• pp.139-146
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• 2004

본 논문에서는 솔더페이스트의 이차원 및 삼차원 자동검사를 함께 할 수 있는 복합 검사 광학계와 그 구동유닛을 단일 프로브 시스템으로 구현하고, 그를 위한 효과적인 비젼검사 알고리즘을 제안하였다. 솔더페이스트의 이차원 검사에는 One-pass Run Length 레이블링 알고리즘을 제안하여 입력 영상으로부터 솔더 페이스트 형상을 효과적으로 추출하도록 하였고, 고속 검사를 위한 프로브의 최적 이동 경로도 구하였으며, 삼차원 검사에는 기존의 레이져 슬릿빔(slit-beam) 방식 대신 격자 투영식 모아레 간섭계에 기반한 위상이동 알고리즘을 도입하여 고정밀 검사가 가능토록 하였다. 전체 소프트웨어 구현에는 MMX 병렬처리기법도 적용함으로써 더욱 고속화 하였다. 10㎜×10㎜의 단위 측정영역(field of view: FOV)에 대하여 x, y 축으로 10㎛ Z축으로 l ㎛의 분해능을 가지는 이차원 및 삼차원 복합 광학 검사 시스템을 제작하여 실험한 결과, 한 FOV에 대한 솔더페이스트의 이차원 및 삼차원 검사를 영상포착 후 각각 평균 11msec와 15msec의 짧은 시간에 처리할 수 있었고, ±1㎛의 두께 측정 정밀도를 얻을 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.36-39
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• 1997

In this paper, we described an approach to design of precision optical system for visual inspection of solder joint defects of SMC(surface mount components) on PCBs(Printed Circuit Board). The illumination system, consisting of three tiered LED lamps and one main camera and four side view camera, is implemented to generated iso-contour on the solder joint according to gradient of the soldered surface. We analyze LED design parameter such as incident angle, diameter of LED ring, and so on to acquire uniform illumination.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1774-1777
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• 1997

As factory automation is required, using the vision system is also essential. Especially, the pateh planning of parts with J-lead on PCB plays a import role of whole automation. Path planning is required because J-lead is scatteed compaed to L-lead on PCB. Therefore, in this paper, we propose path planning of part inspection with J-lead to use Hopfield Model(TSP : Traveling Salesman Problem). Then optical system suited to J-lead inspection is designed and the algorithm of J-lead solder joint and part inspection is proposed.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.7-11
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• 2015

In this paper, an automatic focusing method has been proposed for speedy and reliable measurement and inspection in industry. It is very difficult to determine focusing step size and moving direction in one camera autofocusing. The proposed method can improve speed and accuracy of focusing by using the optical axis interval of two cameras, which is automatically set up as focusing step size. Also, it can determine moving direction from focus value comparisons of two cameras, and then solve ambiguity of one camera focusing. Its performance is verified by experiments. It is expected that it can apply to optical system for measurement and inspection in industry fields.