• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.34-34
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• 2010

Absolute electron-impact cross sections for molecular targets including their radicals are important in developing plasma reactors and testing various plasma processing gases. However, low-energy electron collision data for these gases are sparse and only the limited cross section data are available. In this presentation, the methods and the status of measurements of, mainly, absolute elastic cross sections for electron-polyatomic molecule collisions will be discussed with recent results from Chungnam National University. Elastic cross sections are essential for the absolute scale conversion of inelastic cross sections, as well as for testing computational methods.

• Journal of the Optical Society of Korea
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• v.4 no.2
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• pp.89-93
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• 2000

Recently a new signal processing algorithm for white light interferometry was presented. In this paper, the proposed signal processing algorithm was applied for absolute temperature measurement using white light interferometry. Stability testing and absolute temperature measurement were demonstrated. Stability test demonstrated the feasibility of absolute temperature measurement with an accuracy of 0.015 fringe. The test also showed that the absolute temperature measurement system using white light interferometry is capable of obtaining the theoretical minimum detectable change (0.0005 fringe), which is consistent with the performance predicted by the proposed signal processing algorithm.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.315-324
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• 2004

In eddy current testing(ECT), differential probes have been frequently used since they .an reduce the number of parameters that influence ECT signals. However, differential signal is actually the difference of the two coils' impedance so that signal prediction and interpretation are not easy, On the other hand, absolute coil signal is rather straightforward to predict and analyze. Therefore, combined use of the two types of signals would increase the test reliability. In this paper, absolute coil signals from Inconel plate and tubes are predicted by the finite element analysis and efforts of lift-off, fill-factor, conductivity, operating frequency, test specimen thickness, inner diameter defects, and outer diameter defects are investigated. As a result, various impedance plane diagrams are drawn and analyzed. Significant practical knowldege about absolute signals is accumulated and similar characteristics of the two types of signal could be understood. Finally, slope angle versus defect depth calibration corves are prepared for three different frequencies.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.3
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• pp.201-208
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• 2005

In this paper, absolute and differential eddy current signals from various defects in the steam generator tube are numerically predicted and their signal slope characteristics are investigated. The signal changes due to frequency increase are also observed. After studying signal patterns from various defects and frequencies, the analysis of mixed defect signals affected by the presence of a ferromagnetic support plate is attempted. For the signal prediction, axisymmetric finite element modeling is used and this leads us to the slope angle analysis of the signal. Results show that differential signals are useful for locating the position of a defect under the support plate, while absolute signals are easy to presume and interpret even though the effect of support plate is mixed. Combined use of these two types of signals will help us accomplish a more reliable inspection.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.49
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• pp.135-142
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• 1999

The objective of this paper is to provide an automatic color image testing system capable of synthetically testing a color element like a color tone and a luminance for a color image displayed on the screen, using a CCD camera and a microprocess. The system consists of a CCD camera, a line conveyor, a camera driving part, a remocon, a remote sensing part, a display and a PC including a color vision board and a CPU board. By applying the system to a process, reliability for a testing result can be improved and the absolute criterion to judge a part can be made.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.3
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• pp.174-180
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• 2006

Steam generator (SG) tubes are expanded inside tubesheet holes by using explosive or hydraulic methods to be fixed in a tubesheet. In the tube expansion process, it is important to minimize the crevice gap between expanded tube and tube sheet. In this paper, absolute and differential signals are computed by a numerical method for several different locations of tube expansion inside and outside a tubesheet and signal variations due to tubesheet, tube expansion and operating frequencies are observed. Results show that low frequency is good for detecting tubesheet location in both types of signals and high frequency is suitable for sizing of tube diameter as well as the detection of transition region. Also learned is that the absolute signal is good for measuring tube diameter, while the differential signal is good for locating the top of tubesheet and both ends of the transition region. In the case of mingled anomaly with tube expansion and tubesheet, low frequency inspection is found to be useful to analyze the mixed signal.

• Journal of the Korean Statistical Society
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• v.22 no.1
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• pp.71-81
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• 1993

Among k independent normal populations with unknown means and a common unknown variance, the problem of detecting the population with the largest absolute value of mean is considered. This problem is formulated in a manner close to the framework of testing hypotheses, and the maximum error probability and the minimum power are considered. The power charts necessary to determine the sample size are provided. The problem of detecting the population with the smallest absolute value of mean is also considered.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.4
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• pp.231-238
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• 2006

Nondestructive examination for low pressure turbine disc in standard nuclear power plant using phased array technique was studied. For this purpose, disc mockups were made and notches were machined in the mockups. Detection and length sizing by different methods are compared. Depth of deep notches could be measured by using AATT(absolute arrival time technique) or RATT(relative arrival time technique) but shallow notches that must be detected in early stage couldn't be measured by these two methods. For this case, notch depth was estimated by using signal response angle range and preyed usefulness.

• Genomics & Informatics
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• v.14 no.4
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• pp.187-195
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• 2016

In genetic association studies with high-dimensional genomic data, multiple group testing procedures are often required in order to identify disease/trait-related genes or genetic regions, where multiple genetic sites or variants are located within the same gene or genetic region. However, statistical testing procedures based on an individual test suffer from multiple testing issues such as the control of family-wise error rate and dependent tests. Moreover, detecting only a few of genes associated with a phenotype outcome among tens of thousands of genes is of main interest in genetic association studies. In this reason regularization procedures, where a phenotype outcome regresses on all genomic markers and then regression coefficients are estimated based on a penalized likelihood, have been considered as a good alternative approach to analysis of high-dimensional genomic data. But, selection performance of regularization procedures has been rarely compared with that of statistical group testing procedures. In this article, we performed extensive simulation studies where commonly used group testing procedures such as principal component analysis, Hotelling's $T^2$ test, and permutation test are compared with group lasso (least absolute selection and shrinkage operator) in terms of true positive selection. Also, we applied all methods considered in simulation studies to identify genes associated with ovarian cancer from over 20,000 genetic sites generated from Illumina Infinium HumanMethylation27K Beadchip. We found a big discrepancy of selected genes between multiple group testing procedures and group lasso.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1059-1071
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• 2008

In a balanced factorial design with a nested factor where crossed factors as well as a nested factor exist simultaneously, powers of the rank transformed FR statistic for testing the main, nested and interaction effects are superior to those of the parametric F statistic. In heavy tailed distributions such as exponential and double exponential distributions, powers of the FR statistic show much higher level than those of the F statistic. Further powers of the F and FR statistic for testing the main effect show the highest level in an absolute size as compared with powers of the F and FR statistic for testing the nested and interaction effects. However powers of the FR statistic for testing the nested and interaction effects rather than the main effect are greater in a relative size than powers of F statistic for the all population distributions.