• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.361-365
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• 2003

In this paper, we proposed the effective serial connection methodology of PBG resonator with defect mode. We use the big difference of impedance ratio in connection region, for example dual PBG, for serial connection. This method reduces the PBG cells and is able to control the pole of bandpass filters. This result in flexibility in design of bandpass filter. Our PBG bandpass filter is modeled by using the ideal transmission line model. This model is very easy, fast, and effective for PBG structure.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.606-613
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• 2011

In this paper, patterns of laser scattering and detection of micro defects have been investigated based on Rayleigh criterion for silicon wafer in solar cell. Also, a new laser scattering mechanism is designed using characteristics of light scattering against silicon wafer surfaces. Its parameters are to be optimally selected to obtain effective and featured patterns of laser scattering. The optimal parametric ranges of laser scattering are determined using the mean intensity of laser scattering. Scattering patterns of micro defects are investigated at the extracted parameter region. Among a lot of pattern features, both maximum connected area and number of connected component in patterns of laser scattering are regarded as the important information for detecting micro defects. Their usefulness is verified in the experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.169-174
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• 2012

Reduction unit is one of the most important components for railway vehicle because torque of motor must be transmitted to wheels of vehicle by reduction unit. However, According to advanced studies, it has been often broke down due to the damage, fatigue and wear of gear. To solve this problem, defect diagnosis methods of gear have been mainly using the vibration diagnosis technology through vibration waveform and frequency analysis. However, We should know vibration characteristics of normal state reduction unit prior to defect diagnosis. So in this paper, We had analyzed vibration characteristics of reduction unit in order to utilize monitoring system development. Comparison of targets is the vibration characteristics of normal state reduction unit about Electric Multiple Unit(EMU) and the High-speed trains(KTX, KTX II).

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.359-360
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• 2006

Magnetic Flux Leakage (MFL) methods are widely employed for the non-destructive testing of gas pipelines. In the application of MFL pipeline inspection technology, corrosion anomalies are detected and identified via their leakage filed due to changes in wall thickness. This paper presents discrete cosine transform (DCT) based MFL signal analysis for defect feature extraction of natural gas pipelines. The original MFL signals are transformed into new ones based on the analysis. The usefulness of the approach has been shown by the experimental results.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1402-1404
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• 2009

The silicon nitride films for gate dielectric were deposited by catalytic chemical vapor deposition at low temperature (${\leq}200^{\circ}C$). The mixture of $SiH_4$, $NH_3$ and $H_2$ was used as source gases. The current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of the films were measured. The breakdown voltage and the flat band voltage shift of samples were improved by increase of the $NH_3$ contents and $H_2$ dilution ratio. The defect states were analyzed by photoluminescence (PL) spectra. As the defect states decreased, the breakdown voltage and the flat band voltage shift increased.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.3
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• pp.115-122
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• 2011

The critical role played by manufacturing performance measurement systems in achieving competitive success is increasingly recognized. Developing an integrated performance measurement model is significant for strategic management. This study consist of several principal steps. Performance criteria from the literature and an questionnaire were utilized prior to building the performance model. The AHP(Analytic Hierarchy Process) is utilized to evaluate the weight of each criterion when generating the performance measurement model for Korea automobile parts manufacturing company. AHP analysis showed clear difference in the priority between 5 criteria and 24 sub-criteria in terms of manufacturing performance of Korean automobile parts manufacturing company. The result of priority evaluation in the 5 criteria of 2nd level was ranked quality, cost, delivery, employee, flexibility. And the critical sub-criteria in the 24 sub-criteria of 3rd level was ranked claim rate, process defect rate, outsourcing parts defect rate, ability to quality management innovation, claim cost, etc.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1100-1104
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• 2017

A detector-based approach shows the limited performances for the defect inspections such as shallow fine cracks and indistinguishable defects from background. Deep learning technique is widely used for object recognition and it's applications to detect defects have been gradually attempted. Deep learning requires huge scale of learning data, but acquisition of data can be limited in some industrial application. The possibility of applying CNN which is one of the deep learning approaches for surface defect inspection is investigated for industrial parts whose detection difficulty is challenging and learning data is not sufficient. VOV is adopted for pre-processing and to obtain a resonable number of ROIs for a data augmentation. Then CNN method is applied for the classification. Three CNN networks, AlexNet, VGGNet, and mofified VGGNet are compared for experiments of defects detection.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.27-27
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• 2007

Cu via fill 도금 시, void, seam과 같은 내부 defects는 공정 중 신뢰성을 떨어뜨리며, 전기신호 전달속도를 느리게 한다. 또한 Cu via fell 도금 공정 중 발생하는 과도한 Cu 표면 도금층은 wafer thenning 공정의 생산성 저하와 공정 비용 상승을 유발한다. 3D Interconnection용 직경 30${\mu}$m, 깊이 120${\mu}$m (Aspect Ratio : 4) Via를 이용하여 정류방법, 전류 parameter, 첨가제 조성에 따른 Cu via felling 특성과 overburden두께 변화를 실험적으로 검증하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.24-27
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• 2005

The NDT(Non-Destructive Testing) is valid fur the defect detection of rolling stocks because it can be used to detect defects in invisible places. For example, in case of wheelsets fatigue cracks are initiated in the wheel seat that suffers from fretting fatigue damage. But the conventional ICFPD method can not be applied to detect such cracks in press-fit area of the axle by some technical problems. In this study, we introduced a new ICFPD (Induced Current Focusing Potential Drop) method that can be applied in press-fit area of the axle. And we performed the finite element analysis of the new ICFPD method using measured electromagnetic properties of the wheel and axle. It seems that our approach is very useful f3r the detection of defects in invisible places.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.379-383
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• 2005

This paper proposes a new steel strip surface inspection system. The system acquires bright and dark field images of defects by using a stroboscopic IR LED light and area camera system and the defect images are preprocessed and segmented in real time for feature extraction. 4113 defect samples of cold roll steel strips are used to develop KNN (k-Nearest Neighbor) classifier which classifies the defects into 8 different types. The developed KNN classifier demonstrates about 85% classifying performance which is considered very plausible result.