• Journal of the Korean Data and Information Science Society
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• 제19권2호
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• pp.609-620
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• 2008

There may be several parallel equipments having the same function in a multi-stage manufacturing process, which affect the product quality differently and have significant differences in defect rate. The product quality may depend on what equipments it has been processed as well as what process variable values it has. Applying one model ignoring the presence of different equipments may distort the prediction of defect rate and the identification of important quality variables affecting the defect rate. We propose a procedure for data segmentation when constructing models for predicting the defect rate or for identifying major process variables influencing product quality. The proposed procedure is based on the principal component analysis and the analysis of variance, which demonstrates a better performance in predicting defect rate through a case study with a PDP manufacturing process.

• 교육녹색환경연구
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• 제16권2호
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• pp.1-9
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• 2017

Defect dispute in apartment building has become a debating social issue. The system of defect lawsuit and the conciliation process are applicable to solve defect problems in South Korea. Among various defects, painting work defect is a critical issue because it requires large area works and entails a lot of cost. Accordingly, disputes on work procedure and cost calculation are argued oftenly between residents and housing providers. This study reviewed detailed main issues of painting work and propose relevant systems and standards. In this analysis, the main issues are categorized into pre-works, main work, and others. The most recent cases are compared and analyzed for each issue. After the analysis, following conclusions are obtained, (1) In defect lawsuit system, even though surface treatment work in pre-work step is part of main work, it has been separated and regarded as a separate work. (2) Although the main painting work are not significantly different from two systems, it is still necessary to achieve a consensus to close the gap in the methodology of painting area calculation and determining whole painting or partial painting. (3) In addition, unlike the profit rate of general construction works, that of painting work remained the maximum rate and additional charge rate for works carried out in higher place are different among cases. Therefore, it is determined that establishing consistent standards is urgent.

• 반도체디스플레이기술학회지
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• 제12권2호
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• pp.57-61
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• 2013

This paper presents adaptive neuro-fuzzy inference based defect detection method for various defect types, such as micro-crack, fingerprint and contamination, in heterogeneously textured surface of polycrystalline solar wafers. Polycrystalline solar wafer consists of various crystals so the surface of solar wafer shows heterogeneously textures. Because of this property the visual inspection of defects is very difficult. In the proposed method, we use local binary feature and fuzzy reasoning for defect detection. Experimental results show that our proposed method achieves a detection rate of 80%~100%, a missing rate of 0%~20% and an over detection (overkill) rate of 9%~21%.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.290-291
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• 2021

플라스틱 소재 자동차 부품의 도장 공정에서 불량은 다양한 원인과 현상으로 기인하는데, 온도, 습도, 미세먼지 등 기상환경 조건의 변화에 따라 불량률이 변화하는 연관성을 분석하였다. 실제 도장업체에서 1년 동안 수집한 종류별, 원인별 불량률과 기상환경의 상관성을 머신러닝 기법에 의해 학습하고 시험하여 특정의 기상환경에서 불량률을 예측하였다. 그 결과 실먼지로 인한 불량은 98%, 흐름에 대한 불량은 90%의 불량을 예측하여 모델의 성능을 입증하였다.

• 품질경영학회지
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• 제30권1호
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• pp.144-151
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• 2002

Consider the problem of estimating the confidence interval of defect rate of a specified population through a screening test. Relationship between defect rate of the population and sensitivity and specificity of the screening test is discussed. More general statistical problem is introduced with the assumption of unknown imperfect specificity. An improved version of Hogan & Gladden(1978)'s estimator is proposed and discussed. Simulation studies are performed to compare the efficiency of the proposed estimator with current estimators.

• 대한기계학회논문집A
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• 제23권11호
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• pp.1922-1928
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• 1999

Rotary bending fatigue tests were carried out to investigate the influence of artificial defects on fatigue limit in annealed and austempered ductile iron. Obtained main results are as follows : (1) Artificial defect(micro hole type, dia.<0.4 mm) on specimen surface did not bring about a obvious reduction of fatigue limit in austempered ductile iron(ADI) as compared with annealed ductile iron. (2) According to the investigation of $\sqrt{area}_c$ which is the critical defect size to crack initiation at artificial defect, $\sqrt{area}_c$ of ADI is larger than that of annealed ductile iron. This shows that the situation of crack initiation at artificial defect in ADI is more difficult in comparison with annealed ductile iron. (3) One of the reasons for the low rate of crack initiation from artificial defect in ADI is that the resistance of matrix to crack initiation is higher than that of annealed ductile iron. (4) In case that the $\sqrt{area}$ of artificial defect and graphite nodule is the same, the rate of crack initiation from graphite nodule is higher than that from artificial defect. This reason is that the serious ruggedness around graphite nodule is formed by austempering treatment.

• 품질경영학회지
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• 제20권2호
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• pp.76-93
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• 1992

The purpose of this study, by surveying the status of firms, measurement-related investment and the defect rate, is to analyze the effect of measurement-related investment and to propose a scheme of efficient measurement-related investment which reduces the defect rate. For this project we obtain the data of the status of the measurement-related investment and the defect rate of 928 firms in Korean manufacturing industry by mailing survey. One of our results shows that the firms which have measurement standard laboratory, i.e, which invest in measurement-related area comparatively high, have the defect rate about 0.8% lower than those firms which don't have measurement standard laboratory. Also we find that the small-and-middle size firms have worse measurement-related facility than the large firms and the firms in the heavy-chemical industry have higher measurement-related investment effect than the firms in the light industry.

• 기술사
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• 제33권5호
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• pp.59-64
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• 2000

This improvement case to be introduced of all welders, welding operator, tack welders and welding inspector for reducing of welding defect rate and good quality.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제40권6호
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• pp.266-271
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• 2014

Objectives: The purpose of this study was to analyze the survival rate of reconstruction plates that were used to correct mandibular discontinuity defects. Materials and Methods: We analyzed clinical and radiological data of 36 patients. Only discontinuous mandibular defect cases were included in the study. Reconstruction plate survival rate was analyzed according to age, gender, location of defect, defect size, and whether the patient underwent a bone graft procedure, coronoidectomy, and/or postoperative radiation therapy (RT). Results: Plate-related complications developed in 8 patients, 7 of which underwent plate removal. No significant differences were found in plate survival rate according to age, gender, location of defect, defect size, or whether a bone graft procedure was performed. However, there were differences in the plate survival rate that depended on whether the patient underwent coronoidectomy or postoperative RT. In the early stages ($9.25{\pm}5.10months$), plate fracture was the most common complication, but in the later stages ($35.75{\pm}17.00months$), screw loosening was the most common complication. Conclusion: It is important to establish the time-related risk of complications such as plate fracture or screw loosening. Coronoidectomy should be considered in most cases to prevent complications. Postoperative RT can affect the survival rate and hazard rate after a reconstruction plate is fitted.

• Current Photovoltaic Research
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• 제8권1호
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• pp.17-26
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• 2020

It is clear that monocrystalline Silicon (Si) ingots are the key raw material for semiconductors devices. In the present industries markets, most of monocrystalline Silicon (Si) ingots are made by Czochralski Process due to their advantages with low production cost and the big crystal diameters in comparison with other manufacturing process such as Float-Zone technique. However, the disadvantage of Czochralski Process is the presence of impurities such as oxygen or carbon from the quartz and graphite crucible which later will resulted in defects and then lowering the efficiency of Si wafer. The heat transfer plays an important role in the formation of Si ingots. However, the heat transfer generates convection in Si molten state which induces the defects in Si crystal. In this study, a crystal growth simulation software was used to optimize the Si crystal growth process. The furnace and system design were modified. The results showed the melt-crystal interface shape can affect the Si crystal growth rate and defect points. In this study, the defect points and desired interface shape were controlled by specific crystal growth rate condition.