• Journal of Computational Design and Engineering
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• v.3 no.2
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• pp.91-101
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• 2016

The automated part quality inspection poses many challenges to the engineers, especially when the part features to be inspected become complicated. A large quantity of part inspection at a faster rate should be relied upon computerized, automated inspection methods, which requires advanced quality control approaches. In this context, this work uses innovative methods in remote part tracking and quality control with the aid of the modern equipment and application of support vector machine (SVM) learning approach to predict the outcome of the quality control process. The classifier equations are built on the data obtained from the experiments and analyzed with different kernel functions. From the analysis, detailed outcome is presented for six different cases. The results indicate the robustness of support vector classification for the experimental data with two output classes.

• Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.194-201
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• 2014

Optimization of design is an important step in obtaining tissue engineering scaffolds with appropriate shapes and inner micro-structures. Different shapes and sizes of scaffolds are modeled using UGS NX 6.0 software with variable pore sizes. The quality issue we are concerned is the scaffold porosity, which is mainly caused by the fabrication inaccuracies. Bone scaffolds are usually characterized using a scanning electron microscope, but this study presents a new automated inspection and classification technique. Due to many numbers and size variations for the pores, the manual inspection of the fabricated scaffolds tends to be error-prone and costly. Manual inspection also raises the chance of contamination. Thus, non-contact, precise inspection is preferred. In this study, the critical dimensions are automatically measured by the vision camera. The measured data are analyzed to classify the quality characteristics. The automated inspection and classification techniques developed in this study are expected to improve the quality of the fabricated scaffolds and reduce the overall cost of manufacturing.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.269-278
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• 2004

In this study, hydraulic and hydrologic safety of an existing dam with morning glory spillway was evaluated and the problems were derived in order to control extreme floods efficiently. For design flood(520cms and EL. 170.3m), the spillway was turned out to have no problem for discharge and negative pressure in vertical transition. However, the critical point for discharge starts with EL. 170.7m which transits weir flow condition to orifice flow condition and there may be negative pressure in weir crest. While maximum water level can not be greater than EL. 170.5m including freeboard according to the dam design criteria, the maximum water level based on reservoir routing was turned out to be EL. 172.46m, and fundamental measures should be requested and planned.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.349-350
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• 2012

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.356-362
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• 2009

The ELectromagnetic Core Imperfection Detector (EL-CID) test was performed on a small generator in the laboratory and a gas turbine generator in the field to assess the fault condition of generator stator core. Artificial defects with six different sizes were introduced in the small generator. The scan results on six defects show a very large increase in the magnitude of fault current compared to that obtained with a healthy core. After the stator core heats up, a thermal imaging camera was used to detect hot spot on the inner surface of the core for comparison. Several faults were found during inspection of the gas turbine generator with the EL-CID. It has been shown that the existence of a fault can be determined by monitoring the magnitude of fault current.

• Journal of the Optical Society of Korea
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• v.14 no.2
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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.

• Current Optics and Photonics
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• v.5 no.2
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• pp.173-179
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• 2021

The electroluminescence (EL) intensities of GaN-based light-emitting diodes (LEDs) are estimated based on their photoluminescence (PL) properties. The PL intensity obtained under open-circuit conditions is divided into two parts: the PL intensity under a forward bias lower than the optical turn-on voltage, and the difference between the PL intensities under open-circuit conditions and under forward bias. The luminescence induced by photoexcitation under a constant forward bias lower than the optical turn-on voltage is primarily the PL from the excited area of the LED. In contrast the intensity difference, obtained by subtracting the PL intensity under the forward bias from that under open-circuit conditions, contains the EL induced by the photocarriers generated during photoexcitation. In addition, a reverse photocurrent is generated during photoexcitation under constant forward bias across the LED, and can be correlated with the PL-intensity difference. The relationship between the photocurrent and PL-intensity difference matches well the relationship between the injection current and EL intensity of LEDs. The ratio between the photocurrent generated under a bias and the short-circuit current is related to the ratio between the PL-intensity difference and the PL intensity under open-circuit conditions. A relational expression consisting of the ratios, short-circuit current, and PL under open-circuit conditions is proposed to estimate the EL intensity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.139-146
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• 2004

In this paper, the seismic analysis and the modeling techniques have been introduced for seismic performances assessment, when seismic isolation bearings are applied to a real bridge. Nonlinear time-history analysis is carried out using finite element analysis program. El Centro earthquake(1940, N00W) used as earthquake ground excitations. The seismic response of seismically isolated bridge is compared with that of a bridge using conventional Pot Bearings, after obtaining the displacements of the deck, the deformations of the piers, shear forces and moments of the bottoms of the piers. The analytical analysis results show that seismic isolation bearing, especially seismic isolation bearings with sliding mechanism, could reduce earthquake forces.

• Korean Journal of Optics and Photonics
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• v.20 no.4
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• pp.223-229
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• 2009

This paper describes the development of a simulator which can numerically calculate an image to be acquired in a machine vision system for automated optical inspection. The simulator is based on a ray tracing technique and composed of three modules which are an illuminating system, a specimen and an imaging system. Kinds of model parameters for modules and their values are carefully chosen from the direct measurement and the observation of related phenomena. Finally, the validity of the simulator is evaluated by logical analysis and by comparison with measured images.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1353-1356
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• 2004

In recent year, OLED(organic light emitted display) is used as the next generation device of FPD. OLED have been replacing the flat panel display device such as LCD, STN-LCD and TFT because this device is more efficient, economic and simple than those FPD devices, and this need not backlight system for visualization. The performance and efficiency of OLED is related with surface defect of ITO coated glass substrate. The typical surface defect of glass substrate is nonuniformity and bad surface roughness. ITO coated glass substrate is destroied for inspection about surface roughness and non-uniformity. Generally detection of the defects in the surface for ITO coated glass substrate is dependent on operator's experience. In this research, relationship between working parameter and surface non-uniformity is studied using regression analysis.