• 제어로봇시스템학회논문지
• /
• 제15권9호
• /
• pp.899-905
• /
• 2009

There are many different types of surface defects on semiconductor Integrated Chips (IC's) caused by various factors during manufacturing process, such as Scratch, Flash, Resin bleed, and Melting. These defects must be detected and classified by an inspection system for productivity improvement and effective process control. Among defects, in particular, Resin bleed and Melting are the most difficult ones to classify accurately. The brightness value and the shape of Resin bleed and Melting defects are so similar that normally it is difficult to classify the Resin bleed and Melting. In this paper, we propose a segmenting method and a set of features for detecting and classifying the Resin bleed and Melting defects.

• 한국해양공학회지
• /
• 제20권6호
• /
• pp.1-6
• /
• 2006

Corrosion of reinforcing steel bars is a major concern for ocean engineers when reinforced concrete structures are exposed to marine environments. Evaluating the degree of corrosion and corrosion-induced defects is extremely necessary to pursue a proper retrofit or rehabilitation plan for reinforced concrete structures. A promising inspection should be carried out for the evaluation, otherwise the retrofit or rehabilitation process would be useless. Nowadays, ultrasonic guided wave-based inspection techniques become quite promising for the inspection, mainly because of their long-range propagation capability and their sensitivity to different types of defects or conditions. Evaluating haw the guided waves response to the different types of defects or conditions is quite challenging and important. This study shows how surface conditions of reinforcing bars and a corrosion-induced defect, separation, affect guided wave propagation in reinforced concrete. Experiments and associated signal analysis show the sensitivity of guided waves to the surface conditions, as well as the amounts of separation at the interface between. concrete and steel bar.

• 반도체디스플레이기술학회지
• /
• 제10권1호
• /
• pp.113-118
• /
• 2011

This paper proposes computer visual inspection algorithms for PCB defects which are found in a manufacturing process. The proposed method can detect open circuit and short circuit on bare PCB without using any reference images. It performs adaptive threshold processing for the ROI (Region of Interest) of a target image, median filtering to remove noises, and then analyzes connected components of the binary image. In this paper, the connected components of circuit pattern are defined as 6 types. The proposed method classifies the connected components of the target image into 6 types, and determines an unclassified component as a defect of the circuit. The analysis of the original target image detects open circuits, while the analysis of the complement image finds short circuits. The machine vision inspection system is implemented using C language in an embedded Linux system for a high-speed real-time image processing. Experiment results show that the proposed algorithms are quite successful.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.61-62
• /
• 2006

A new neural network classifier is proposed for the automatic real-time surface inspection of high-speed cold steel strips having 11 different types of defects. 46 geometrical and gray-level features are extracted for the defect classification. 3241 samples of Posco's Kwangyang steel factory are used for training and testing the neural network classifier. The developed classifier produces plausible 15% error rate which is much better than 20-30% error rate of human vision inspection adopted in most of domestic steel factories.

• 한국구조물진단유지관리공학회 논문집
• /
• 제2권1호
• /
• pp.98-107
• /
• 1998

There are many weld defects such as surface crack, lack of fusion, and imcomplete penetration in the butt joint of the existing steel bridges. The crack-like defects may significantly reduce the fatigue life of the structure. This paper presents the procedure and the results of the fatigue assessment of the butt joints with weld defect in the existing steel girder bridge. The butt joints with imcomple penetration were instrumented with strain gages to determine the stress histogram under normal traffic. Based on the measured stress histogram the crack propagation analyses were performed for the fatigue assesment. By using the suggested procedure and methodology, one can decide the time of periodic inspection and the necessity of repair of the butt joints with serious weld defects in the existing steel bridge.

• 한국정밀공학회지
• /
• 제24권4호
• /
• pp.76-83
• /
• 2007

A new neural network classifier is proposed for the automatic real-time surface inspection of high-speed cold steel strips having 11 different types of defects. 46 geometrical and gray-level features are extracted for the defect classification. 3241 samples of Posco's Kwangyang steel factory are used for training and testing the neural network classifier. The developed classifier produces plausible 15% error rate which is much better than 20-30% error rate of human vision inspection adopted in most of domestic steel factories.

• 반도체디스플레이기술학회지
• /
• 제18권3호
• /
• pp.60-65
• /
• 2019

In this paper, the hybrid illumination system for effectively detecting surface defects in steel plate with lowcontrast, non-uniformity and featureless is designed based on illuminance uniformity. First of all, characteristics of steel plate defects were considered and typical inspection illumination system is implemented. Optimum illumination parameters for uniformly illuminating an inspection area in the typical illumination system are selected based on the illuminance uniformity and illuminance distribution measurement. The illuminance uniformity and illuminance distribution are measured using an illuminometer based on the arduino. Through illuminance distribution analysis of the typical illumination, an hybrid illumination is designed by fusing bi-directional illumination and coaxial illumination. The hybrid illumination showed higher uniformity ratio and illuminance distribution than the typical illuminations. The hybrid illumination system showed the ability to uniformly illuminate the entire inspection region of steel plate surface.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.241-244
• /
• 2006

It is essential to develop a large capacity, non-contact nondestructive inspection system having high reliability to investigate repaired and strengthened structures. Nowadays, an infrared camera is widely used in non-contact nondestructive inspection system. Because an infrared camera is sensitive to the surrounding environment, it is necessary to improve a sensitivity of thermal image information and a relationship between defects and thermal image information. In this papaer, presented is an optimum void detection chart for the optimum conditions to detect infrared rays from inside and outside defects like voids and cracks in concrete structures using extensive computer simulation. Sensitivity studies are performed with respect to variables influencing the temperature distribution such as heating temperature, heating time, and geometries of defect, etc. It may be stated that it could be successfully utilized for the non-contact nondestructive inspection system to detect defects in concrete structures.

• 한국산학기술학회논문지
• /
• 제18권2호
• /
• pp.335-341
• /
• 2017

본 논문은 모터 샤프트 제조 공정에서 발생하는 이중컷 불량을 검사하기 위한 영상 처리 알고리즘을 제안하였다. 알고리즘은 영상의 밝기를 이용하여 외곽선을 추출하는 단계와 추출된 외곽선을 이용하여 이진화된 경계선 그래프를 구하는 단계, 최종적으로 이진화된 경계선 그래프를 이용하여 불량품을 판정하는 단계로 구성된다. 본 논문에서는 두 절단면이 분리되어 있는 결함과 두 절단면이 연결되어 있는 결함을 각각 type 1 결함과 type 2 결함이라고 정의하였다. 실제 제조 과정에서 112개의 양품과 44개의 불량품 (type 1 불량 34개 및 type 2 불량 10개) 샘플을 수집하였으며, 수집한 샘플을 이용하여 제안된 알고리즘을 검증하였다. 알고리즘 시험 결과 100% 정확도로 양품과 불량품을 판정하였으며, 불량품의 경우도 type 1 불량과 type 2 불량을 정확히 구분하는 것으로 확인되었다. 본 논문에서 제안한 알고리즘은 추가적으로 다양한 샘플에 대해 신뢰성을 확보한 후 실제 현장에 사용할 계획이다.

• 대한기계학회논문집A
• /
• 제28권12호
• /
• pp.2004-2011
• /
• 2004

The applicability of the ultrasonic C-scan inspection is restricted due to the deterioration of mechanical properties of specimen during the test. Therefore, the aim of this research is applied to Eddy Current (EC) test substitute for the C-scan inspection in CFRP tube containing defects. This research is to evaluate the EC signals for the inspection of CFRP tube containing various circular hole defects (20% to 100% depth to the specimen thickness) using the unloading specimen and radial loading specimen. This study was considered the following points; 1) Analysis of EC signals for the inspection of saw-cut defect and circular hole defect, 2) The evaluation of defect depths and EC signals relationship. 3) Variation of EC signal owing to the radial load. In conclusions, the high frequency such as 300∼500 kHz made it possible to the inspection of 40% to 100% defects. Particularly, in case of 20% defect, the EC signal was not detected due to the noise of micro-crack and delamination. While the depth of the hole defects were decreasing, the difference of the phase angle between unloading specimen and radial loading specimen was gradually increasing.