• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.111-117
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• 2011

Vibration monitoring is required for reliable thermosonic testing to decide whether sufficient vibration is achieved in each test for the detection of cracks. From a practical point of view, a cheaper and convenient monitoring method is better for the application to real tests. Therefore, the performance of different sensors for vibration monitoring was investigated and compared in this study to find a convenient and acceptable measurement method for thermosonics. Velocity measured by a laser vibrometer and strain provide an equivalent HI when measured at the same position. The microphone can provide a cheaper vibration monitoring device than the laser and the heating index calculated by a microphone signal shows similar characteristics to that calculated from velocity measured by the laser vibrometer. The microphone frequency response shows that it underestimates high frequency components but it is applicable to practical tests because it gives a conservative value of HI.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.343-346
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• 2004

In recent years, various forms of indentation testing have been increasingly used to determine the material properties of specimens. This technique, particularly the nano-indentation method , has been extended to the testing of coating systems in order to calculate the individual properties of the thin coatings and the substrates. However, the interpretation of the test data to achieve this is complex and continues to be a widely studied subject. Based on the finite element method of coated surfaces indented by a Berkovich diamond tip, this paper describes methods for combining FEM and experimental indentation testing to determine coating modulus and hardness independent of substrate effects. Using this proposed methodology, testing and FEM to measure coefficients of friction of sheet steel for outer panel were studied.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.2
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• pp.79-85
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• 2011

This study has been experimented about refrigeration capacity difference. It has been used 3 method, Manual expansion valve, thermostatic expansion valve and capillary expansion valve, and tested under the same condition by using the performance testing of parallel expansion. In temperature change of the temperature room, thermostatic expansion valve method displayed the most lower temperature, $-18^{\circ}C$. In addition, the temperature, just before the expansion, also displayed the best result which was $4^{\circ}C$ lower than other expansion valve. In these results, it can be used for performance testing of parallel expansion refrigeration system.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.93-96
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• 2014

RFID (Radio Frequency IDentification) system is recognition technology which can maintain various object's information. Reliability of RFID tags is the most important factor in RFID system. In this paper, we proposed ALT (Accelerated Life Test) method for UHF RFID tags. Temperature and humidity were adopted as stress factors and the accelerated life tests were conducted in three different conditions. We performed failure analysis for identifying failure mechanism and statistical analysis of test data. In the statistical analysis, we employed Inverse Power law for relationship between tag's life and stress. Through the statistical analysis, we proposed acceleration factor for several levels of temperature-humidity. The reliability qualification test plans were also designed for the tag's target reliability.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1263-1270
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• 2000

The operation frequency of High-speed Communication System becomes very fast with the advanced technology of VLSI chips and system implementation. There may exist various types of noise sources degrading the signal integrity in this system. The present main system is made of backplane, so faults can be brought whenever a board is removed, replaced or added. This backplane boards testing is a very important process to verify the operation of system. firstly, we model the effects of the internal noises in the High-speed Communication System to the signal line and propose a new design method to minimize these effects. For the design methodology, we derive the characterization value for each mode land them construct the optimal simulation model. We compare the result of own proposing method with that fo the existing methods, through simulation and show that the quality of High-speed Communication System is significantly enhanced. Secondary our proposing BIST for the Backplane Boards Testing is designed to guarantee that there is no fault in the high-speed communication system.

• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.4
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• pp.244-249
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• 1995

Infrared(IR) thermography method was developed as a result of an investigation into a means of deriving a more visual method of temperature analysis. It recently provides an excellant nondestructive testing(NDT) technique in a variety of industries such as nuclear power plant, fossil plants, etc.. This paper offers a basic principles of infrared radiation, the nature of instruments used for measurement and the applications.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2319-2321
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• 2002

This paper suggests a computer-based on-line measurement method of tan$\delta$ and capacitance for HV capacitor. The method employs V-I technique using scaled down analog voltage and current signal obtained by digital oscilloscope. The measurement results are displayed by graphic user interface with graphic language. Field tests were tarried out at 6.6kV testing voltage in Samhwa Capacitor company.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.14 no.2
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• pp.53-56
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• 2008

Polyvinylchloride(PVC) is variously used to produce food packaging, wrap film, sealing compound of drinking bottle cap. Safety of these PVC food package is controlled by Food Code, PVC regulation. This study was carried out researches on manufacture process, physical, chemical properties and monomer(CAS No., common name, molecular structure) of PVC to help the understanding of PVC material. Also, this study helps us the understanding of regulation through researches on the foundation of PVC regulation, the purpose of test and the comment of test method. It is considered that these informations of material properties and explanations of test method are very useful to PVC producers, users and analyzers of them.

• Journal of the Korea Society of Computer and Information
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• v.20 no.10
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• pp.23-29
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• 2015

In this paper, we suggest a method of detecting defects by applying Hough transform and least squares on ceramic images obtained from non-destructive testing. In the ceramic images obtained from non-destructive testing, the background area, where the defect does not exist, commonly show gradual change of luminosity in vertical direction. In order to extract the background area which is going to be used in the detection of defects, Hough transform is performed to rotate the ceramic image in a way that the direction of overall luminosity change lies in the vertical direction as much as possible. Least squares are then applied on the rotated image to approximate the contrast value of the background area. The extracted background area is used for extracting defects from the ceramic images. In this paper we applied this method on ceramic images acquired from non-destructive testing. It was confirmed that extracted background area could be effectively applied for searching the section where the defect exists and detecting the defect.

• Journal of the Korea Society of Computer and Information
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• v.7 no.1
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• pp.27-32
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• 2002

Software reuse was focused for the way of improving programmer productivity from the crisis of software. Object oriented technology impact on overall area of software engineering, such as software analysis , Programming language. testing and maintenance. The new concepts, Class, Inheritance and encapsulation, not only introduce new testing problems and they raise a new challenging question of how to conduct regression testing for 0-0 programs the first problem of regression testing is how to identify the affected components due to the changes of some components. We propose a method firewall to enclose all classes and methods affected by the changes to one or more methods in Inheritance relation