• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.56-61
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• 2000

We present a fast inspection method of machine vision for in-line quality assurance of liquid crystal displays(LCD) and plasma display panels(PDP). The method incorporates an optical spatial filter in the Fourier plane of the imaging optics to block the normal periodic pattern, extracting only defects real time without relying on intensive software image process. Special emphasis is on designing a collimated white light source to provide high degree of spatial coherence for effective real time Fourier transform. At the same time, a low level of temporal coherence is attained to improve defect detection capabilities by avoiding undesirable coherent noises. Experimental results show that the proposed inspection method offers a detection accuracy of 15% tolerance, which is sufficient for industrial applications.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.51-54
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• 2003

Internal defects such as chevron crack occasionally occur in the process of cold extrusion or cold drawing. It is known that the existence and property of inclusion greatly influences the generation of the internal crack. However, in the plastic working field, research about the effect of the inclusion on the fracture is not theoretically analyzed. This paper describes effects of the physical property of inclusion on the internal fracture generation in the process. Prediction of fracture was evaluated by critical damage value calculated by the equation of Cockcroft & Latham and its change by the inclusion physical property such as size and stiffness was investigated.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2414-2417
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• 2005

Compact Camera Module(CCM) is widely used in PDA, Celluar phone and PC web camera. With the greatly increasing use for mobile applications, there has been a considerable demands for high speed production of CCM. The major burden of production of CCM is assembly of lens module onto CCD or CMOS packaged circuit board. After module is assembled, the CCM is inspected. In this paper, we developed the image capture board for CCM and the imaging processing algorithm to inspect the defects in captured image of assembled CCMs. The performances of the developed inspection system and its algorithm are tested on samples of 10000 CCMs. Experimental results reveal that the proposed system can focus the lens of CCM within 5s and we can recognize various types of defect of CCM modules with good accuracy and high speed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.391-394
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• 2018

논문에서는 스마트 공장의 표면결함검사 시스템에 사용할 수 있는 Haar, Ferns, MCT 영상의 특징 활용방법에 관한 연구를 다루었습니다. 본문에서 Haar, Ferns, MCT 특징에 관해 소개하였고, 실험에서 머신비전을 이용한 표면결함검사에 이 특징들이 사용될 수 있음을 결과를 통해 제시하였다.

• Current Optics and Photonics
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• v.3 no.5
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• pp.438-444
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• 2019

In this theoretical study, a line-defect photonic-crystal waveguide hosted in an annular photonic crystal was demonstrated to provide high-performance slow light with a wide band, low group-velocity dispersion, and a large normalized delay-bandwidth product. Combined with structural-parameter optimization and selective optofluid injection, the normalized delay-bandwidth product could be enhanced to a large value of 0.502 with a wide bandwidth of 58.4 nm in the optical-communication window, for a silicon-on-insulator structure. In addition, the group-velocity dispersion is on the order of $10^5$ ($ps^2/km$) in the slow-light region, which could be neglected while keeping the signal transmission unchanged.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.849-852
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• 2021

This paper presents a vision based tire mold inspection system where mold defects are inspected and the sizes of specific parts of the mold are measured. There are a lot of challenging issues as letters and pictures of intaglio are engraved on a bright surface of the tire mold. To solve the issues, we carefully selected a line-scan camera and a line light. In addition, we used PLC to control the mechanical parts. The developed system provides inspection of misspelled and deformed letters as well as a variety of the functions such as size measurement of engraved regions and inspection report file creation.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.687-697
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• 2022

An automated system is needed for the effectiveness of non-destructive testing. In order to utilize the radiographic testing data accumulated in the film, the types of welding defects were classified into 9 and the shape of defects were analyzed. Data was preprocessed to use deep learning with high performance in image classification, and a combination of one-stage/two-stage method and convolutional neural networks/Transformer backbone was compared to confirm a model suitable for welding defect detection. The combination of two-stage, which can learn step-by-step, and deep-layered CNN backbone, showed the best performance with mean average precision 0.868.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.65-66
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• 2021

본 논문에서는 Smart Factory의 자동 공정에서 결함의 분류를 실시간으로 시도하여 자동 공정 제어를 위한 결함 분류 딥러닝 기법을 제안하고, Pooling 종류에 따른 분류 성능을 비교한다. Smart Factory 구축에 있어서 CNN을 이용한 공정 제어를 통해 제품 생산에 있어서 생산량의 증가와 불량률의 감소를 이루어내는 것이 가능하다. Smart Factory는 자동화 공정이므로 결함의 분류 속도가 중요하지만, 생산량의 증가와 불량률의 감소를 위해서는 정확하게 결함의 종류를 분류하여 Smart Factory의 공정을 제어하는 것이 더욱 중요하다. 본 논문에서는 Pooling을 Max Pooling과 Averrage Pooling을 복합적으로 설정하였을 때 높은 성능을 보였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.101-106
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• 2020

This research is related to a development of the ultrasonic detector for an internal defect detection of various assembly part's welding zone. In this research, measurement S/Ws including system's motion control, S/W ultrasonic transmitter/receiver control, defect judgment standard setting, etc. have been designed for ultrasonic detection, and welding defects sample network, etc. were also designed for comparison between products in good condition and defective products. Through this kind of system, automatic detection function can be performed for the depth and the defect location of the assembly parts welding zone, and the system is able to make a judgment of internal defect detection which is used to be performed by an expert in the past.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.8 s.350
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• pp.1-5
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• 2006

At-wavelength inspection system of extreme Ultra-violet lithography was developed and the inspection results were compared with the optical mask inspection system by cross correlation experiments. In at-wavelength EUV mask inspection system, a raster scan of focused euv light is used to illuminate euv light to mask blank and specularly and non-specularly reflected euv light are detected by photo diode and microchannel plate. The cross correlation results between at-wavelength inspection tool and optical inspection tool shows strong correlation. Far-field scattering fringe pattern from programmed phase and opqque defect, which were detected by phosphor plate and CCD camera shows that distinct diffraction fringes were observed with fringe spacing dependent on the defect size.