• Proceedings of the KSME Conference
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• 2001.06a
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• pp.529-533
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• 2001

NDI technique system using AC current is newly developed for inspection of defects. This technique is non-contact measurement system and can be applied for locating and sizing of surface defects in components. In this paper, the technique was applied for evaluating the location and size for 2-dimensional surface cracks and we had investigated the influence of frequency and lift-off. The results show that defects are able to detect with the variety of voltage, and the measuring voltage for the depth of defects are under the influence of the measuring frequency and the lift-off.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.113-121
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• 2013

The road icing forecast and snow detection system using state evaluation algorithm of multi sensor optimizes snow melting system to control spread time and amount of chemical spread application This system operates integrated of contact/non-contact sensor and infrared camera. The state evaluation algorithm of the system evaluates road freezing danger condition and snowfall condition (snowfall intensity also) using acquired data such as temperature/humidity, moisture detection and result of image signal processing from field video footage. In the field experiment, it proved excellent and reliable evaluated result of snowfall state detection rate of 89% and wet state detection rate of 94%.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.94.3-94
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• 2001

A sensor system was developed to measure displacement of civil structure at a long distance. A He-Ne Laser tube and photodiodes ware used for non-contact measurement. This system allows real time vibration displacement measurement of bridges. The measured displacement data is displayed on computer monitor graphically and also in digit. The accuracy of the displacement measurement shows 2mm in vertical vibration. It shows remote inspection of the vibration of long bridges and buildings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.171-177
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• 2011

The feasibility of using low cost, unpowered, unshielded dynamic microphones is investigated for cost effective contactless sensing of impact-echo signals in concrete structures. Impact-echo tests on a delaminated concrete slab specimen were conducted and the results were used to assess the damage detection capability of the low cost system. Results showed that the dynamic microphone successfully captured impact-echo signals with a contactless manner and the delaminations in concrete structures were clearly detected as good as expensive high-end air pressure sensor based non-contact impact-echo testing.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.4
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• pp.294-299
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• 1999

In this paper, the calibration system for contact transducer has been developed to improve the reliability of the inspection result of ultrasonic testing on rotors. This system consists of signal processing parts: (oscilloscope, spectrum analyzer, pulser/receiver), standard block, and user interface program. Signal processing for the calibration system was performed quickly with high accuracy. The developed system has been applied to a practical calibration of probe using the non-destructive testing on rotors, and demonstrated high sensitivity and precision.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1079-1080
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• 2008

To improve productivity of TFT-LCD and PDP, it is required that the inspection system of flat glass should be established. It is composed of robot arms, base table, and laser sensors. This paper focuses on three non-contact laser sensors. After testing three laser sensors, LG-G30 is selected.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.412-419
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• 2003

The most product is manufactured by mould in usual life. From drawing to manufacturing is to be automatically. But inspection is handwork usually. An alternative idea of this problem is reverse engineering. In this study, press forming is measured by 3D non-contact coordinate measuring machine and problem will be analyzed by comparing with 3D data Through the study, it will achieve improvement of press mould process.

• Journal of the Semiconductor & Display Technology
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• v.5 no.1 s.14
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• pp.1-4
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• 2006

Recently, Ball Grid Arrays(BGAs) are getting used more frequently for a package type. The connectors on a BGA consist of a large number of small solder balls in a grid shape on its bottom side. However, since balls of BGAs mounted on PCBs are not visible, inspection before mounting them is indispensable. High speed non-contact 3D measurement technologies are necessary far real-time measurement of ball height, the most important inspection item. In this paper, an accurate 3D data acquisition system for BGAs is proposed that can acquire 3D profile at high speed using a 3D smart camera and laser slit ray projection. Some clipping and morphological filtering operations are employed to remove spiky error data, which occur due to reflections from some ball area to camera direction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.70-79
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• 2020

The main objective of this research to develop an IoT based wireless contactless ultrasonic system (ICUS) and its application to concrete structure. The developed system consists of 16 mems, 2Mhz digitizer, amplifying circuit, FPGA, and wifi module, enabling to measure leaky surface waves from concrete specimens without physical coupling process and wires. Multi-channel analysis is performed to improve the accuracy of data analysis, and the velocity of leaky surface waves and acoustics are derived. Field inspection of railroad concrete sleepers is conducted to evaluate the performance of the system and to compare the results with conventional ultrasonic pulse velocity (UPV). As a result of the field inspection, UPV was limited to evaluate damages. This is because crack pattern of railroad sleepers is parallel to ultrasonic ray path and accessibility of the railroad at the field is disadvantageous to contact-based UPV. On the other hand, ICUS possibly detect the damages as reduction of dynamic modulus by up to 59% compared to non-damaged specimen.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.137-142
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• 2001

Since recent production system becomes that of the small quantity, large volume with high quality production, accurate and high speed inspection system is required. In such situation, noncontact 3D measurement system which utilized CCD cameras is useful technique in terms of system cost, speed of data acquisition, measuring accuracy and application. However, it has low accuracy compared with contact 3D measurement system because of the camera distortion, non uniformity of laser distribution and so on. For those reasons, in this paper precision enhancement method is studied considering radial camera distortion, and laser distribution. A distortion correction method is applied even to the standard lens. The laser slit beam trajectory is determined by 3 method: based of the Gaussian function signal approximation, the median method, the center of gravity method and the peak point of the Gaussian function method.