• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2532-2537
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• 2009

For defect characterization in steam generator tubes in nuclear power plant, artificial neural network has been extensively used to classify defect types. In this paper, we study the effectiveness of Bagging for improving the performance of neural network for the classification of tube defects. Bagging is a method that combines outputs of many neural networks that were trained separately with different training data set. By varying the number of neurons in the hidden layer, we carry out computer simulations in order to compare the classification performance of bagging neural network and single neural network. From the experiments, we found that the performance of bagging neural network is superior to the average performance of single neural network in most cases.

• Journal of Magnetics
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• v.18 no.2
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• pp.202-206
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• 2013

In this paper, the MFL (magnetic flux leakage) signals of complex defects on the underground gas pipeline are analyzed and their depths are estimated. Since closely-located defects (complex defects) affect each other, accelerate the progress of defection, and are finally combined to one (cluster), it's meaningful to differentiate complex defects from single defects by analyzing their characteristics. Various types of complex defects are characterized and analyzed by defining the safety distance for interference. 26 artificial defects are carved on the pipeline simulation facility (PSF) to analyze the characteristics of complex defect and demonstrate the accuracy of the proposed complex defect estimation. The proposed method shows average length error of 5.8 mm, average width error of 15.55 mm, and average depth error of 8.59%, respectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.604-613
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• 2009

Recently, researches to develop phased array ultrasonic examination techniques are proceeded to diagnose dental caries and the status of surgical operation of dental implant. Sound field analysis of phased array ultrasonic transducers were carried out in order to characterizing the ultrasonic phased array beams. The sound field of ultrasonic radiation was calculated for the sample called "gypsum-improved stone" with the similar characteristics of dental materials. Industrial phased array ultrasonic devices were utilized for the insptriion of the artificial flaws machined in the gypsum-improved stone. Dental implants were made at the pig jaw bone and defect images were confirmed for the dental implants.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1320-1326
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• 1988

This paper deals with the behavior of surface crack growth and the characteristics of surface micro-crack distribution under creep and creep-fatigue with 1 min. and 10 min. of load holding times at 593.deg.C, in air. The test specimen is a plate type with a small artificial defect of type 304 the small defect has been carried out by the surface replica method and optical microphotography. The experimental results have been interpreted from the view-point of fracture mechanics. It can be concluded that the longer the hold time the longer the total life time. Most of surface micro-cracks initiate at grain boundaries before the specimen reaches 20% of its total life time, a few of them lead to fracture by coalescence with the main crack.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.168-169
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• 2022

As the electric vehicle market has grown rapidly, the battery market has grown exponentially. Due to the gap between the generation speed of quality control technology and battery mass production speed for batteries mounted on electric vehicles, many durability problems have arisen for batteries. Most accidents are caused by electrical factors, but there is no technology to quickly inspect them. In this paper, we are going to propose a quick analysis of battery cell defects using the GAN model.

• Archives of Plastic Surgery
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• v.33 no.5
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• pp.601-605
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• 2006

Purpose: Large skin defect by various causes, should be covered by autologous skin graft. But, the donor site of autologous skin graft is limited and leaves permanent donor scar and contracture. There have been our trial to engineer artificial skin using allogenic dermis (AlloDerm) with basement membrane. Methods: Dermal and epidermal layer were separated by immersing in dipase solution for 30 minutes, and the separated layers were treated with 0.05% trypsin for 10 minutes. And then each layer was cultivated to fibroblasts and keratinocytes on a culture medium. Fibroblasts were first penetrated into basement membrane of allogenic dermis facing down, then allogenic dermis was flipped over to face up and keratinocytes were transplanted to allogenic dermis. Results: Observing artificial skin fabricated in vitro, we found following: 1) The artificial skin opened in air for 5 days formed epidermal layer. In dermal layer, fibroblast was distributed evenly among all. 2) The artificial skin opened in air for 30 days formed thicker and thicker, and it formed basement membrane, spinous and granular layers. PAS stain to confirm existence of basement membrane showed positive reaction. 3) Cytokeratin 10 stain to confirm the formation of epidermal layer showed positive reaction. 4) The formation of thick keratin, lamellar body and desmosome similar to human skin were observed in result of an electron micrograph. Conclusion: As a result of research, the structure seen in normal skin such as rete ridge, is found in reproduced artificial skin. This type of artificial skin can be used as a useful model for investigating skin disease and for clinical application also.

• Archives of Plastic Surgery
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• v.48 no.2
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• pp.208-212
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• 2021

Background There are currently no guidelines for the postoperative wound management of the hard-palate donor site in cases involving mucosal harvesting. This study describes our experiences with the use of an artificial dermis for early epithelialization and transparent plate fixation in cases involving hard-palate mucosal harvesting. Methods A transparent palatal plate was custom-fabricated using a thermoplastic resin board. After mucosal harvesting, an alginic acid-containing wound dressing (Sorbsan) was applied to the donor site, which was then covered with the plate. After confirming hemostasis, the dressing was changed to artificial dermis a few days later, and the plate was fixed to the artificial dermis. The size of the mucosal defect ranged from 8×25 to 20×40 mm. Results Plate fixation was adequate, with no postoperative slippage or infection of the artificial dermis. There was no pain at the harvest site, but a slight sense of incongruity during eating was reported. Although the fabrication and application of the palatal plate required extra steps before and after harvesting, the combination of the artificial dermis and palatal plate was found to be very useful for protecting the mucosal harvest site, and resulted in decreased pain and earlier epithelialization. Conclusions The combination of artificial dermis and a transparent palatal plate for wound management at the hard-palate mucosal donor site resolved some of the limitations of conventional methods.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.33-39
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• 1995

This paper presents a method of detecting localized defects on tapered roller bearing in main spindle of machine tool system. The statistical parameters in time-domain processing technique have been calculated to extract useful features from bearing vibration signals. These features are used by the input feature of an artificial neural network to detect and diagnose bearing defects. As a results, the detection of bearing defect conditions could be successfully performed by using an artificial neural network with statistical parameters of acceleration signals.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.12
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• pp.671-678
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• 2003

This paper proposes an expert system to generate automatically the test table of test system which can highly enhance the quality and productivity of product by inspecting quickly and accurately the defect device on the electronic circuit board tested. The expert system identifies accurately the tested components and the circuit patterns by tracing automatically the connectivity of circuit from electronic circuit database. And it generates automatically the test table to detect accurately the missing components, the misplaced components, and the wrong components for analog components such as resistance, coil, condenser, diode, and transistor, based on the experience knowledge of veteran expert. It is implemented in C computer language for the purpose of the implementation of the inference engine using the dynamic memory allocation technique, the interface with the electronic circuit database and the hardware direct control. And, the validity of the builded expert system is proved by simulating for a typical electronic board model.