• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.221-228
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• 2010

A construction firm's performance is largely attributable to performance in individual projects. In this regard, the awarding of an individual project has significant implications. However, project awards have received limited attention in the construction sector from amarket assessment perspective. This event study focuses on an analysis of market responses at the time of project awarding. A total of 252 samples wereselected through a rigorous sample screening processes. Performance was measured as cumulative abnormal return, which is traditionally adopted in event analysis. Research results indicated that the overall return is positive, and that the level isstatistically significant. Equity holders realized a higher return for projects awarded from the foreign countries compared to domestic projects. No relationship was observed between project size and the level of return. Other research findings and implications were discussed in detail from a management perspective.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2547-2554
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• 2009

In this paper, we proposed a face detection algorithm and a hardware implementation method for ROI(Region Of Interest) of AF(Auto Focusing). We used face features in skin regions of YCbCr color space for face detection. The face features are the number of skin pixels in face regions, edge pixels in eye regions, and shadow pixels in lip regions. The each feature was statistically selected by 2,000 sample pictures of face. The proposed algorithm detects two faces that are closer center of the image for considering the effectiveness of hardware resource. The detected faces are displayed by rectangle for ROI of AF, and the rectangles are represented by positions in the image about starting point and ending point of the rectangles. The proposed face detection method was verified by using FPGA boards and mobile phone camera sensor.

• The KIPS Transactions:PartD
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• v.11D no.6
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• pp.1269-1276
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• 2004

The Parameter Estimation for software existing reliability models, Goel-Okumoto, Yamada-Ohba-Osaki model was reviewed and Rayleigh model based on Rayleigh distribution was studied. In this paper, we discusses comparison of parameter estimation using maximum likelihood estimator and Bayesian estimation based on Gibbs sampling to analysis of the estimator' pattern. Model selection based on sum of the squared errors and Braun statistic, for the sake of efficient model, was employed. A numerical example was illustrated using real data. The current areas and models of Superposition, mixture for future development are also employed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1100-1105
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• 2006

Severe distortions of colors in the obtained images have made it difficult for color codes to expand their applications. To reduce the effect of color distortions on reading colors, it will be more desirable to statistically process as many pixels in the individual color region as possible, than relying on some regularly sampled pixels. This process may require segmentation, which usually requires edge detection. However, edges in color codes can be disconnected due tovarious distortions such as zipper effect and reflection, to name a few, making segmentation incomplete. Edge linking is also a difficult process. In this paper, a more efficient approach to reducing the effect of color distortions on reading colors, one that excludes precise edge detection for segmentation, was obtained by employing the k-means clustering algorithm. And, in detecting color codes, the properties of both six safe colors and grays were utilized. Experiments were conducted on 144, 4M-pixel, outdoor images. The proposed method resulted in a color-code detection rate of 100% fur the test images, and an average color-reading accuracy of over 99% for the detected codes, while the highest accuracy that could be achieved with an approach employing Canny edge detection was 91.28%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2523-2529
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• 2009

The purpose of this study was to observe the demineralization effects of children's range beverage on bovine enamel. 15 bovine teeth without dental caries were divided into 4 experimental groups (n=12) and control group (n=3). All samples immersed in beverages maintained 48 hours by $37^{\circ}C$ in incubate respectively. The surface microhardness values(${\Delta}VHN$) between before and after 48 hours treatment decreased and DIGNOdent value increased because enamel surface were corroded by experimentation beverage. Especially, there was statistical significantly difference in the carbonated drink. Morphological changes by scanning electron microscope were indicated that children's range beverage cause significant enamel demineralization effects on bovine tooth surface among five beverages.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3046-3050
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• 2014

The purpose of the present study was to evaluate the effect of 7-point interval scale(EAI) and visual analogue scale(VAS) on perceptual judgement and the reliability of severity on voice problems by dysphonic speakers. 30 undergraduate students studying communication disorder were enrolled in the perceptual evaluation. Those listeners judged overall voice severity within the anchored(condition 1) and non-anchored scales(condition 2) for vowel prolongation and reading tasks by 25 speakers with voice disorder. The results of this study showed that the scores by VAS was significantly higher than EAI in both condition 1 and condition 2 for vowel prolongation and reading task. However, the scores by EAI method was higher than by VAS method on voice severity of vowel prolongation (condition 1) and reading task(condition 2). These results suggest auditory-perceptual scaling procedures must be more studied in the aspects of clinical application of voice disorder.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.749-756
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• 2021

Thanks to PLC and IoT Sensor, huge amounts of data has been accumulated onto the companies' databases. Machine Learning Algorithms for the predictive model with good performance have been widely utilized in the manufacturing process. We present how to improve the performance of machine learning predictive models. To improve the performance of the predictive model, typical techniques such as increasing the sample size, optimizing the hyper parameters for the algorithm, and selecting a proper machine learning algorithm for the predictive model would be shown. We suggest some new ways to make the model performance much better. With the proposed methods, we can build a better predictive model for predicting and controlling product qualities and save incredibly large amount of quality failure cost.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.317-323
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• 2022

This study aimed to qualitative analyze the cusp variation pattern of the mandibular second premolars using a three-dimensional virtual models, and to analyze the left-right bilateral symmetry with a quantitative analysis of the tooth surface area according to the cusp variation. 127 virtual mandibular second premolars were prepared and individual absolute/relative cusp area, total crown area and groove form were analyzed using RapidForm2004(INUS technology INC, Seoul, Korea). Independent t-test, Kruskal-Wallis test and chi-square were performed. As a result, the groove form showed high bilateral symmetry between the left and right sides. Based on the left side of groove form, the bilateral symmetry was 100.0% for the U pattern, and 73.7% for the H patterned, and 78.9% for the Y pattern(p<.001). The finding could be as a meaningful reference for manufacturing CAD/CAM dental prostheses, and it is expected that further studies will be conducted on more samples including the mandibular second premolar immediately after eruption.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.283-288
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• 2022

The study aimed to investigate the psychological effect of the emotional insect-assisted healing program on the stress experienced by 43 children in a community child center. Silkworm (Bombyx mori [Linnaeus]) was used in the healing programs, and the stress was measured using salivary alpha-amylase levels. Saliva samples and a survey on insect preference were collected before and after the healing programs, respectively. After the program, the satisfaction score for participation was evaluated. Results indicate that the emotional insect-assisted healing programs led to statistically significant lowering of salivary alpha-amylase levels and increased the preference for insects. The children's satisfaction in the healing program activities using silkworms was 4.23 points out of 5.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.507-516
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• 2022

The purpose of this study was to examine the factors influencing on the smartphone usage time according to the happiness perceived by adolescents. This study underwent the approval procedure for using the raw data of the 13th (2017) Adolescents' Health Behavior Online Survey through the homepage of Korea Centers for Disease Control and Prevention and selected 54,603 persons of 12-18 age groups as subjects of the study. The analysis was performed after generating a complex sample plan file by assigning weights using the IBM SPSS 23.0 program. There were significant differences in general characteristics and physical & psychological characteristics according to the use of the smartphone in the happy group and the unhappy group (p<.05). And there was a statistically significant difference in factors affecting smartphone usage time between the group of adolescents who perceived as happy and the group who perceived themselves as unhappy. It is necessary to improve the quality of life by increasing the level of happiness through the correct use of smartphones among adolescents.