• Journal of Chest Surgery
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• v.13 no.4
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• pp.418-421
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• 1980

During the period from August 1959 to end of July 1980, 69 cases of Type I VSD were noted among 235 cases of ventricular septal defect who were operated utilizing cardiopulmonary bypass in the Department of Cardio-thoracic Surgery, College of Medicine, Seoul National University(29.4%). During the same period 1162 open heart surgery cases were experienced among whom 778 cases were congenital anomalies. There were no significent differences between Type I '||'&'||' other tvpo:s of VSD in sex and age distribution. In Type I VSD frequency of aortic regurgitation association was much higher than rest of the types. (8.7% to 2.6%). Necessity of patch closure in Type I was not different from other types. The high incidence of Type I VSD is quite similar to Japanese references which show quite higher ratio compared with from Euroamerican caucasian patients materials. All cases were operated on with bubble type oxygenator mainly Shiley**" oxygenator utilizing hypothermic hemodilution perfusion technique.echnique.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2006-2008
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• 2004

In this paper the imitated electric defect was simulated by insulation particle in the model GIS. This paper studied the distribution of frequency spectrum of the radiated electromagnetic waves using antenna (30-2,000[MHz]) and spectrum analyzer. From results of this study, a new method was introduced for measurement and analysis of the radiated electromagnetic waves in accordance with discharge progress of each defect in the model GIS. It was confirmed that detecting partial discharge and estimating discharge progress can be possible in the model GIS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.397-398
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• 2009

In oder to investigate of partial discharge of nano-composites materials, we have studied partial discharge appling voltage from 5 to 30 [kV] to make an artificial defect with the epoxy adding to 0, 0.4, 0.8, and 1.6 [wt%], respectively. The experimental result, we have found that $SiO_2$ of 0.4 (wt%] was superior to others also, it is found that the effect of isolate diagnosis to get the slope for the discharged electric charge distribution.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.34
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• pp.3-26
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• 2007

Product liability law lies at the center of the modem world. This law concerns liability for damages arising from the commercial sale of a product that causes personal injury or property damage because it was defective or falsely represented. One engaged in the business of selling or otherwise distributing products who sells or distributes a defective product is subject to liability for harm to persons or property caused by the defect. In short, product defectiveness is the heart of products liability law. Regardless of the underlying cause of action, the plaintiff in nearly every products liability case must prove that the defendant's product contained an unnecessary hazard that caused the harm. The purpose of this paper is to clarify the meaning of the product defectiveness to products liability claims in China. In China, Product to include most movable personal property, but to exclude services. And a product is defective when, at the time of sale or distribution, it contains a manufacturing defect, is defective in design, or is defective because of inadequate instructions or warnings.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.102-102
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• 2010

A purpose of this paper is to recognize partial discharge pattern for cable insulation. The classification of PD sources was widely studied for two decades. this research sought to use the partial discharge detection method, and to diagnose the interface of cable, which is deemed vulnerable of cable systems. A research abalyzed faults that can occur in the interface of cable joint as well as accident mechanisms, manufactured test 22.9kV CNC cable, invented artificial faults and carried out partial discharge detection experiments. As a result, various PD pattern along defect measured and distinguished.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.499-505
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• 1998

In developing an automated surface inspect algorithm, we have designed a hierarchical classifier using neural network. The defects which exist on the surface of cold mill strip have a scattering or singular distribution. We have considered three major problems, that is preprocessing, feature extraction and defect classification. In preprocessing, Top-hit transform, adaptive thresholding, thinning and noise rejection are used Especially, Top-hit transform using local minimax operation diminishes the effect of bad lighting. In feature extraction, geometric, moment, co-occurrence matrix, and histogram ratio features are calculated. The histogram ratio feature is taken from the gray-level image. For defect classification, we suggest a hierarchical structure of which nodes are multilayer neural network classifiers. The proposed algorithm reduced error rate by comparing to one-stage structure.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.491-497
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• 1999

The effect of partial squeeze on the quality of casting products in the vacuum die casting was investigated to make defect free casting products with excellent mechanical properties. The partial squeeze and vacuum die casting process was industrially implemented in making reaction shaft support which was made of a hypereutectic Al-15%Si alloy. To combine squeezing and vacuum effects, the plunger injection system was designed and attached on the chill vent type vacuum machinery system. The combination of vacuum effect before injection and partial squeezing effect after injection resulted in defect free die casting products. The uniform distribution of fine eutectic and proeutectic Si obtained from trial process also provided excellent mechanical properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.10-14
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• 2001

In order to assess the long-tenn reliability of polymer insulators for distribution power systems, we have developed the accelerated aging test method which can simulate the operation conditions. In this study, 3000 hours aging test for 4 kinds of polymer insulators has been completed by the developed accelerated aging test. After 3000 hours aging test, visual inspection and electrical tests were carried for identifying a change of characteristics. Some specimens showed the surface erosion and the manufacturing defect. In the electrical tests, the wet flashover voltage was significant1y decreased by the accelerated aging test. In comparison with the field-aged polymer insulators, it can be concluded that the developed test method can evaluate the long-tenn reliability within short time and screen the manufacturing defect.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.112-119
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• 2000

A die-casting junction method is usually used to manufacture the tub of an IH(induction heating) jar. If there is a very small air bubble in the junction area, the thermal conductivity is deteriorated and local overheat occurs. Such problem brings serious inferiority of the IH jar. In this paper, we propose a new method to detect such defect with simply measured thermal data. Thermal distribution of preheated tubs is obtained by scanning with infrared thermal sensors and analyzed with the statistic pattern recognition method. By defining the characteristic feature as the temperature difference between sensors and using ellipsoid function as decision boundary, a supervised learning method of genetic algorithm is proposed to obtain the required parpameters. After applying the proposed method to experiment, we have proved that the rate of recognition is high even for a small number of data set.

• 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.