• Journal of the Korea Institute of Building Construction
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• v.9 no.2
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• pp.93-101
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• 2009

Recently, public interest in housing defects, such as construction errors, occupiers' complaints, faults in production, and so on, is increasing. In addition, the construction requirements of high-rise residential buildings have increased, due to the higher prices of urban areas, especially in metropolitan areas. While previous research has focused on the defects occurring in apartment housing complexes, research has not been carried out on the defects occurring in high-rise residential buildings. In this paper, the defects patterns and characteristics of high-rise residential buildings are examined and analyzed and a defect management plan is then suggested. In order to do this, we collected the defects data of high-rise residential buildings recorded by 2,299 of 2,327 occupants. The defect occurrence rate (DOR) in the residential area is 98.8%. The frequency rate of defect occurrence over the total defect occurrence since building completion is 63.28% during the first year, 24.63% (second year), 6.88% (third year), 2.27% (fourth year), and 2.53% (fifth year). The result of correlation analysis between work types showed that there is a relationship between the built-in furniture and electronics (F&E) and painting works, and the F&E and masonry works, such as marble finishing. We expect that this research will assist in the efforts to decrease the number of defects in high-rise buildings.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.11
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• pp.989-995
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• 2015

In the literature, various stochastic anomaly detection methods, such as limit checking and PCA-based approaches, have been applied to weld defect detection. However, it is still a challenge to identify meaningful defect patterns from very limited sensor signals of laser welding, characterized by intermittent, discontinuous, very short, and non-stationary random signals. In order to effectively analyze the physical characteristics of laser weld signals: plasma intensity, weld pool temperature, and back reflection, we first transform the raw data of laser weld signals into the form of event logs. This is done by multidimensional discretization and event-codification, after which the event logs are decoded to extract weld defect patterns by $Na{\ddot{i}}ve$ Bayes classifier. The performance of the proposed method is examined in comparison with the commercial solution of PRECITEC's LWM$^{TM}$ and the most recent PCA-based detection method. The results show higher performance of the proposed method in terms of sensitivity (1.00) and specificity (0.98).

• Transactions of Materials Processing
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• v.31 no.4
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• pp.229-239
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• 2022

Convolution Neural Network(CNN) is a class of deep learning algorithms and can be used for image analysis. In particular, it has excellent performance in finding the pattern of images. Therefore, CNN is commonly applied for recognizing, learning and classifying images. In this study, the surface defect classification performance of Al 6061 extruded material using CNN-based algorithms were compared and evaluated. First, the data collection criteria were suggested and a total of 2,024 datasets were prepared. And they were randomly classified into 1,417 learning data and 607 evaluation data. After that, the size and quality of the training data set were improved using data augmentation techniques to increase the performance of deep learning. The CNN-based algorithms used in this study were VGGNet-16, VGGNet-19, ResNet-50 and DenseNet-121. The evaluation of the defect classification performance was made by comparing the accuracy, loss, and learning speed using verification data. The DenseNet-121 algorithm showed better performance than other algorithms with an accuracy of 99.13% and a loss value of 0.037. This was due to the structural characteristics of the DenseNet model, and the information loss was reduced by acquiring information from all previous layers for image identification in this algorithm. Based on the above results, the possibility of machine vision application of CNN-based model for the surface defect classification of Al extruded materials was also discussed.

• Archives of Plastic Surgery
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• v.37 no.5
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• pp.667-670
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• 2010

Purpose: The management of urethral defect represents one of the most challenging clinical problems in uroplastic surgery. Especially for defect after Fournier's Gangrene, optimal management is still a hard problem. During extensive urethral reconstruction, to overcome the poor vascularity due to periurethral scarred tissue and limitation of the choice of local flap, we report our experience with one-stage reconstruction of urethral defect using a longitudinal tubed flap of scrotal skin. Methods: A 72-year-old man with several years of diabetes mellitus history visited for swelling and pain of scrotal area. After diagnosis of Fournier's Gangrene, radical debridement was performed and 6 cm of urethral defect on border of penile-scrotal ventral area was made. Rectangular scrotal skin flap ($6{\times}2.5\;cm$) based on external spermatic fascia was elevated and tubed longitudinally. After transfer the flap to the defect area, end-to-end anastomosis was performed bilaterally. Results: 4 weeks after the operation, the patient started voiding him-self and urethrography showed good fluence of contrast agent. Long term evaluation reveals stable performance characteristics without any complications. Conclusion: We suggest a one-stage reconstruction of extensive urethral defect using a longitudinal tubed flap of scrotal skin. Advantages of this procedures are simple, one-stage reconstruction with the reliable scrotal skin flap based on external spermatic fascial vasculature, and no donor morbidity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.596-602
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• 2018

Nanoimprint lithography (NIL) is an emerging technology that enables cost-effective and high-throughput nanofabrication. In ultraviolet (UV) NIL, low-cost and high-speed production can be achieved using a non-vacuum environment at room temperature and low pressure. However, there are problems with the formation of bubble defects in such an environment. This paper investigates the shape of the mold cavity and the bubble defect formation in UV NIL in a non-vacuum environment. The bubble defect formation was simulated using two-dimensional flow analysis and the VOF method for commonly used cavity mold shapes (rectangular, elliptical, and triangular). The characteristics of the resist flow front and various contact angles were also analyzed. The shape of the mold cavity had a very significant effect on the bubble defect formation. For all cavity shapes, a smaller contact angle with the mold and larger contact angle with the substrate decreased the possibility of bubble defect formation. The elliptical shape was the most effective for preventing bubble defect formation.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.197-206
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• 2015

Defect severity that is a measure of the impact caused by the defect plays an important role in software quality activities because not all software defects are equal. Earlier studies have concentrated on defining defect severity levels, but there have almost never been trials of measuring module severity. In this paper, first, we define a defect severity metric in the form of an exponential function using the characteristics that defect severity values increase much faster than severity levels. Then we define a new metrics set for software module severity using the number of defects in a module and their defect severity metric values. In order to show the applicability of the proposed metrics, we performed an analytical validation using Weyuker's properties and experimental validation using NASA open data sets. The results show that ms is very useful for measuring the module severity and msd can be used to compare different systems in terms of module severity.

• Archives of Craniofacial Surgery
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• v.20 no.1
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• pp.17-23
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• 2019

Background: The resection of head and neck cancer can result in postoperative defect. Many patients have difficulty swallowing and masticating, and some have difficulty speaking. Various types of flaps are used for palatal reconstruction, but flap selection remains controversial. Therefore, our study will suggest which flap to choose during palatal reconstruction. Methods: Thirteen patients who underwent palatal reconstruction from 30 January, 1989 to 4 October, 2016 at our institution. Size was classified as small when the width was < $4cm^2$, medium when it was $4-6cm^2$, and large when it was ${\geq}6cm^2$. Based on speech evaluation, the subjects were divided into a normal group and an easily understood group. After surgery, we assessed whether flap selection was appropriate through the evaluation of flap success, complications, and speech evaluation. Results: Defect size ranged from $1.5{\times}2.0cm$ to $5.0{\times}6.0cm$. In four cases, the defect was in the anterior third of the palate, in eight cases it was in the middle, and there was one case of whole palatal defect. There were three small defects, two medium-sized defects, and eight large defects. Latissimus dorsi free flaps were used in six of the eight large defects in the study. Conclusion: The key to successful reconstructive surgery is appropriate selection of the flap with reference to the characteristics of the defect. Depending on the size and location of the defect, the profiles of different flaps should be matched with the recipient from the outset.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.1
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• pp.60-70
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• 2021

Recently, with the development of technologies for the fourth industrial revolution, convergence and complex technology are being applied to aircraft, electronic home appliances and mobile devices, and the number of parts used is increasing. Increasing the number of parts and the application of convergence technologies such as HW (hardware) and SW (software) are increasing the No Defect Found (NDF) phenomenon in which the defect is not reproduced or the cause of the defect cannot be identified in the subsequent investigation systems after the discovery of the defect in the product. The NDF phenomenon is a major problem when dealing with complex technical systems, and its consequences may be manifested in decreased safety and dependability and increased life cycle costs. Until now, NDF-related prior studies have been mainly focused on the NDF cost estimation, the cause and impact analysis of NDF in qualitative terms. And there have been no specific methodologies or examples of a working-level perspective to reduce NDF. The purpose of this study is to present a practical methodology for reducing NDF phenomena through data mining methods using quantitative data accumulated in the enterprise. In this study, we performed a cluster analysis using market defects and design-related variables of mobile devices. And then, by analyzing the characteristics of groups with high NDF ratios, we presented improvement directions in terms of design and after service policies. This is significant in solving NDF problems from a practical perspective in the company.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.653-664
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• 2021

As the construction standards for energy-saving eco-friendly housing have recently been strengthened, the proportion of window work has increased with the demand for high-efficiency housing. Windows have high frequency of use, and there is the potential for many defects to occur depending on the characteristics of construction. According to a government agency's survey of defects in public rental apartment housing, defects in the windows work accounted for the highest portion of complaints received. Accordingly, related previous studies were considered, and it was found that the existing studies in Korea lacked research that reflected the construction characteristics of window work and the importance of maintenance. In addition, existing overseas studies considered both the constructor and the resident's position, considering the cost aspect together, and showed a trend of structuring the relationship between defects and causes. Therefore, this study will analyze the causes of defects that can occur in the construction phase of the windows work, reflect the construction characteristics, and derive major factors that consider the importance of maintenance based on the possibility of recurrence after repairing defects. Ultimately, this research will contribute to preventing defects in the construction phase and reducing maintenance costs by presenting a highly effective defect management plan through selecting the major factors for each defect type that can be intuitively judged by analyzing the causal relationship between defect types and causes.

• Macromolecular Research
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• v.10 no.2
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• pp.75-79
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• 2002

Organic materials have considerable attention as active semiconductors for device applications such as thin-film transistors (TFTs) and diodes. Pentacene is a p-type organic semiconducting material investigated for TFTs. In this paper, we reported the morphological and electrical characteristics of pentacene TFT films. The pentacene transistors showed the mobility of 0.8 $\textrm{cm}^2$/Vs and the grains larger than 1 ${\mu}{\textrm}{m}$. Deep-level transient spectroscopy (DLTS) measurements were carried out on metal/insulator/organic semiconductor structure devices that had a depletion region at the insulator/organic-semiconductor interface. The duration of the capacitance transient in DLTS signals was several ten of seconds in the pentacene, which was longer than that of inorganic semiconductors such as Si. Based on the DLTS characteristics, the energy levels of hole and electron traps for the pentacene films were approximately 0.24, 1.08, and 0.31 eV above Ev, and 0.69 eV below Ec.