• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.615-623
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• 2006

The purpose of this study was to evaluate the specificity, sensitivity, and diagnostic power of caries activity test using LED fluorescence. The subjects of this study were 55 children of $6{\sim}7$ years old. LED light were irradiated to labial or buccal surface of all teeth. Fluorescence from initial carious lesion of teeth illuminated by an LED light was observed through barrier filter and the number of teeth showing lesion, size and position of lesion were counted. Streptococcus mutans colony counting and dDfFtT rate test were also done and their correlation was compared. And then specificity, sensitivity, diagnostic power of optical caries activity test using LED light were evaluated. 1. There was positive $correlation({\gamma}=0.43)$ between LED fluorescence test and Streptococcus mutans count(P<0.05). 2. When visual examination was defined to standard testing method, the specificity, sensitivity, diagnostic power of LED fluorescence test were 100%, 76.1%, and 100%. 3. When dDfFtT rate was defined to standard testing method, the specificity, sensitivity, diagnostic power of LED fluorescence test were 88.9%, 47.8%, and 95.7%. 4. When S. mutans colony counting was defined to standard testing method, the specificity, sensitivity, diagnostic power of LED fluorescence test were 100%, 58.7%, and 100%. Considering the above results, optical caries activity test using LED light could be regarded as a practical method because of its close relationship with microbiological caries activity test.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.135-140
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• 2001

The radar method is becoming one of the major nondestructive testing (NDT) techniques for concrete structures. Numerical modeling of electromagnetic wave is needed to analyze radar measurement results and to study the influence of measurement parameters on the radar measurements. Finite difference-time domain (FD-TD) method is used to simulate electromagnetic wave propagation through concrete specimens. In the experiments, three concrete specimens are made with the dimensions of 100 cm (length) x 100 cm (wideth) x 14 cm (depth). Three specimens had a Dl6 steel bar at 8, 10, 12 cm depth.

• KCI Concrete Journal
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• v.12 no.1
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• pp.139-144
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• 2000

Ground Penetrating Radar (GPR) with 1 GHz antenna has been used to locate a steel bar embedded inside laboratory-prepared mortar specimens. Four mortar specimens are made with the dimensions of 100 cm (length) x 100 cm (width) x 14 cm (depth). One specimen had no bars and the other three specimens had a Dl9 steel bar at 4, 6. and 8 cm depth. As a part of the experimental work, the dielectric constants of mortar specimens are measured during curing. As the curing time increased. the dielectric constant decreased with decreasing moisture content inside the specimen. The steel bar embedded inside mortar specimens has been successfully identified in all three cases. The results using signal processing scheme developed in this study significantly improved the output of a commercially available radar system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.654-661
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• 2011

This paper is about a personal identification algorithm using an ECG that has been studied by a few researchers recently. Previously published algorithm can be classified as two methods. One is the method that analyzes of ECG features and the other is the morphological analysis of ECG. The main characteristic of proposed algorithm can be classified the method of analysis ECG features. Proposed algorithm adopts DSTW(Down Slope Trace Wave) for extracting ECG features, and applies SVM(Support Vector Machine) to training and testing as a classifier algorithm. We choose 18 ECG files from MIT-BIH Normal Sinus Rhythm Database for estimating of algorithm performance. The algorithm extracts 100 heartbeats from each ECG file, and use 40 heartbeats for training and 60 heartbeats for testing. The proposed algorithm shows clearly superior performance in all ECG data, amounting to 93.89% heartbeat recognition rate and 100% ECG recognition rate.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.94-100
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• 2011

This paper gives a brief overview of the COMS CPS development process from start to finish. The manufacturing techniques used for CPS were founded on established generic processes that have been developed and proven on previous satellite programs, and have used the expertise and facilities in the framework of international collaboration. Manufacture and testing of the CPS were successfully accomplished, and COMS CPS demonstrated good performance in the launch phase.

• Proceedings of the Acoustical Society of Korea Conference
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• 1987.11a
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• pp.48-51
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• 1987

In this paper, acoustic reflection microscope system has been built for the purpose of detecting subsurface defects in materials and demonstrated for nondestructive testing application. 100 won coin, aluminuim, ceramics, and IC component employed as experimental samples and acoustic reflection microscope was operated in the focused and defocused mode at a frequency of operation of 3 MHz. It has been found that acoustic reflection icroscope has the resolution of 500 ${\mu}{\textrm}{m}$ and it has been an excellent tool for nondestructive testing.

• Journal of the Korean Statistical Society
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• v.27 no.1
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• pp.11-23
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• 1998

A Bayes criterion for testing the equality of covariance matrices of two multivariate normal distributions is proposed and studied. Development of the criterion invloves calculation of Bayes factor using the imaginary sample method introduced by Spiegelhalter and Smith (1982). The criterion is designed to develop a Bayesian test criterion, so that it provides an alternative test criterion to those based upon asymptotic sampling theory (such as Box's M test criterion). For the constructed criterion, numerical studies demonstrate routine application and give comparisons with the traditional test criteria.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.2 no.2
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• pp.100-103
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• 1973

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.405-411
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• 2015

Objectives: The purpose of this study is to evaluate the optimum conditions for oral mucosal irritation testing using the buccal pouch of hamsters. Methods: Test materials were applied to the buccal pouch of seven-week old male Syrian hamsters (SLC, Japan) four times at one-hour intervals and macroscopic changes were examined at 24 hours after final treatment. After sacrifice, the buccal pouches were removed and prepared for histopathological evaluation. In order to set the exposure time, we performed exposure tests of 5, 12, 18 and 23 minutes using sodium lauryl sulfate (SLS) 1% and set the treatment volume from the test results at 2, 3, or 4 ml treatment using SLS 1%, Triton X-100 1% and ethanol. After setting the experimental conditions, seven groups of materials [sodium lauryl sulfate (SLS) (1%), Triton X-100 (1%), hydrogen peroxide (3%), ethanol (100%), chlorhexidine (0.2%, 2%), phosphate buffer saline (PBS)] were assessed. Results: Experimental conditions of material exposure time were fixed as 18 minutes from the exposure tests of 5, 12, 18 or 23 min using sodium lauryl sulfate (SLS) 1%. Treated volume was set as 4 ml per each pouch from the test results of 2, 3, or 4 ml treatments using SLS 1%, Triton X-100 1% and ethanol. The results in terms of irritation degree were in the order of sodium lauryl sulfate (SLS) (1%) > Triton X-100 (1%) ${\fallingdotseq}$ hydrogen peroxide (3%) > ethanol (100%) ${\fallingdotseq}$ chlorhexidine (0.2%, 2%) > phosphate buffer saline (PBS). Conclusion: From this study, suitable conditions for hamster mucosal irritation testing were suggested and this method was verified through materials commonly used on oral mucosal membranes.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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• pp.93-101
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• 2016

This paper presents the results obtained using time-series-based methods for structural damage assessment. The methods are applied to a wind turbine blade structure subjected to fatigue loads. A 9 m CX-100 (carbon experimental 100 kW) blade is harmonically excited at its first natural frequency to introduce a failure mode. Consequently, a through-thickness fatigue crack is visually identified at 8.5 million cycles. The time domain data from the piezoelectric active-sensing techniques are measured during the fatigue loadings and used to detect incipient damage. The damage-sensitive features, such as the first four moments and a normality indicator, are extracted from the time domain data. Time series autoregressive models with exogenous inputs are also implemented. These features could efficiently detect a fatigue crack and are less sensitive to operational variations than the other methods.