• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.259-264
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• 2006

It is well known that the uncertainty of the covariance parameters of the process noise (Q) and the observation errors (R) has a significant impact on Kalman filtering performance. Q and R influence the weight that the filter applies between the existing process information and the latest measurements. Errors in any of them may result in the filter being suboptimal or even cause it to diverge. The conventional way of determining Q and R requires good a priori knowledge of the process noises and measurement errors, which normally comes from intensive empirical analysis. Many adaptive methods have been developed to overcome the conventional Kalman filter's limitations. Starting from covariance matching principles, an innovative adaptive process noise scaling algorithm has been proposed in this paper. Without artificial or empirical parameters to be set, the proposed adaptive mechanism drives the filter autonomously to the optimal mode. The proposed algorithm has been tested using road test data, showing significant improvements to filtering performance.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.111-118
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• 2008

In usual safety signs are final means to transmit hazard information so that the importance of them cannot be emphasized too much. Nevertheless, in Korea, few people are interested in functions of safety signs so that evaluation of safety signs are seldom committed. This research was conducted to evaluate and compare perceptional characteristics of safety signs, especially "Fall" signs, by Semantic Differential Method and Multi-dimensional Scaling Method, with undergraduate students as well as industrial workers. According to research results on several signs evaluated high through suggested procedure, action inducibility was different for students majoring in different sciences, but it had common elements in the sense of 'openness' or 'arrangements'. Besides, perceptional images on safety signs were mainly recognized with bases of 'arrangement' for student group and 'simplicity' for industrial workers, respectively, and their maps corresponded well with each other by partial rotating so that students and workers seemed to recognize safety signs with similar factors though their name might be different. However, since perceptional characteristics including image map, comprehensibility, and action inducibility were similar for student group whereas those were not for worker group, it was concluded that the test for action inducibility would be absolutely necessary for safety signs for workers' group.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.452-472
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• 2019

Most existing wavelet-based multiplicative watermarking methods are affected by geometric attacks to a certain extent. A serious limitation of wavelet-based multiplicative watermarking is its sensitivity to rotation, scaling, and translation. In this study, we propose an image watermarking method by using dual-tree complex wavelet transform with a multi-objective optimization approach. We embed the watermark information into an image region with a high entropy value via a multiplicative strategy. The major contribution of this work is that the trade-off between imperceptibility and robustness is simply solved by using the multi-objective optimization approach, which applies the watermark error probability and an image quality metric to establish a multi-objective optimization function. In this manner, the optimal embedding factor obtained by solving the multi-objective function effectively controls watermark strength. For watermark decoding, we adopt a maximum likelihood decision criterion. Finally, we evaluate the performance of the proposed method by conducting simulations on benchmark test images. Experiment results demonstrate the imperceptibility of the proposed method and its robustness against various attacks, including additive white Gaussian noise, JPEG compression, scaling, rotation, and combined attacks.

• Journal of Distribution Science
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• v.21 no.2
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• pp.35-43
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• 2023

Purpose: As Thailand seeks to become a regional startup hub, Thai startups have been acquiring growth and scalability in the last ten years. Hence, this paper examines influential factors in Thailand's growth of logistics tech startups. The conceptual framework incorporates sensing user needs, sensing technological options, conceptualizing, scaling, and stretching, co-producing, and orchestrating, business strategy, strategic flexibility, and startup growth. Research design, data, and methodology: The quantitative method was applied to distribute the questionnaire to 500 managers and above in logistics tech startups in Thailand. The sampling techniques involve judgmental, convenience, and snowball samplings. Before the data collection, The Item Objective Congruence (IOC) Index and pilot test (n=45) were employed for content validity and reliability. The data were mainly analyzed by Confirmatory Factor Analysis (CFA) and Structural Equation Model (SEM). Results: The findings revealed that sensing technological options, scaling, and stretching, co-producing, and orchestrating, and business strategy significantly influence the growth of startups in Thailand. Nevertheless, sensing user needs, conceptualizing, and strategic flexibility have no significant relationship with startup growth. Conclusions: For Thailand to accelerate its digital economy driven by tech startups, firms must emphasize influential factors to accelerate growth by providing the right tech solutions for people's lives.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.6
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• pp.309-317
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• 2022

In this paper, we propose a machine learning-based copy-move forgery detection network with dual branches. Because the rotation or scaling operation is frequently involved in copy-move forger, the conventional convolutional neural network is not effectively applied in detecting copy-move tampering. Therefore, we divide the input into rotation-invariant and scaling-invariant features based on the wavelet coefficients. Each of the features is input to different branches having the same structure, and is fused in the combination module. Each branch comprises feature extraction, correlation, and mask decoder modules. In the proposed network, VGG16 is used for the feature extraction module. To check similarity of features generated by the feature extraction module, the conventional correlation module used. Finally, the mask decoder model is applied to develop a pixel-level localization map. We perform experiments on test dataset and compare the proposed method with state-of-the-art tampering localization methods. The results demonstrate that the proposed scheme outperforms the existing approaches.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.183-192
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• 1993

The purpose of this epidermiological analysis was to evaluate the periodontal status of Korean young adults(twenties) in order to provide detail & baseline data for frequence of periodontal disease. Two hundred and fifty young adults, aged 20-29 years, were selected by random sampling. Dental visity, scaling treatment, education, income, toothbrushing frequence & method were checked, and plaque index(Loe and silness), calculus index(Ramfjord), gingival index(Loe and silness), attached gingival width, perio probing depth, gingival recession were measured. The obtained results were as follows. 1. Average plaque index(1.96), calculus index(1.43), gingival index(1.7) were higher in mandible than maxillar. It was most prevalent in lst molar. 2. Average attached gingival width(4.0mm) was wider in maxillar than mandible. It was most prominent in lateral incisor. 3. Pocket depth(>4mm) was distributed in 42% subject, it was higher in mandible than maxilla and most prevalent in 1st molar. 4. Gingival recession(>1mm) was distributed in 94% subject, it was higher in mandible than maxilla, and most prevalant in canine. 5. According to unpaired t-test, palque index, calculus index, gingival index were not statistically significant in history of scaling treatment, level of eduction and account of income, but were showed statistically significant in histrory of dental clinic.(PB0.05) 6. According to ANOVA test, correlation between tooth-brushing(frequence, method) and gingival index was showed statistically significant.(P<0.05) 7. There was gingival recessionof 87% subject in only one time brushing, 80% subject in two time, and 68% subject in three times. There was gingival recessionof 68% subject in leftright direction tooth brushing, 73% subject in upper-low method and 77% subject in combination method.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.29-36
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• 2008

In this paper, the orbital forming analysis of an automotive hub bearing was studied to predict forming performances using the explicit finite element method. To find an efficient solution technique for the orbital forming, axisymmetric finite element models and 3D solid element models were solved and numerically compared. The time scaling and mass scaling techniques were introduced to reduce the excessive computational time caused by small element size in case of the explicit finite element method. It was found from the numerical simulations on the orbital forming that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations at the inner race of bearing were quite different. Finally the strains at the inner race of bearing and the forming forces to the peen were measured for the same product of the numerical model by test, and were compared with the 3D solid element results. It was founded that the test results were in good agreements with the numerical ones.

• Journal of Korean society of Dental Hygiene
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• v.12 no.4
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• pp.647-654
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• 2012

Objectives : To propose the data for prevention of oral health problems through assessment on the knowledge, cognition and practice about oral health care of the clients who visit dental clinics. Methods : The subjects were total 400 clients from the four dental clinics in Busan city. Their knowledge, cognition and performances about oral healthcare collected with questionnaire survey from February to March, 2011. The rate and mean compared by chi-square test, t-test, and ANOVA. Results : Mean level of their knowledge, recognition and practice were 72.5, 80.2, and 65.6, respectively. Theses levels were higher in women (p<0.01), in the group of higher interested (p<0.001), immediately treated (p<0.001), correct tooth brushing (p<0.05), toothbrushing educated (p<0.001), take regular scaling (p<0.001), use assistant hygiene items (p<0.001), instead no differences by age and education level. And, the rate of correct toothbrushing was higher as 1.24 (1.03~1.50) times in the group with higher knowledge level, the rate of immediate treatment and regular scaling were higher as 1.35 (1.07~1.70) times, and 2.26 (1.41~3.64) times in the group with higher recognition level, respectively. Conclusions : These results demonstrate that insufficient knowledge and recognition of oral health care are related to a lack of its practice. Though their primary goal of the visits was treatment, the clients' attention needed to raise the comprehensive knowledge and recognition levels for their oral health promotion, especially reach to the performance level rather than simple knowledge acquisition. And more, to achieve the efficient oral health promotion, the importance of early treatment and strengthened efforts for prevention should be emphasized.

• Journal of dental hygiene science
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• v.11 no.3
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• pp.213-220
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• 2011

To examine the relationship between occurrence of oral malodor and smoking, drinking, oral health behavior characteristics. A total of 144 adults were measuring the malodor by use of Oral Chroma volatile sulfur compounds. Data were analyzed with t-test, one-way of variance and multiple regression analysis using SPSS 12.0. hydrogen sulfide($H_2S$) was indicated to be so higher concentration in the group of carrying out scaling sometimes than the regularly group(p<0.01). methyl mercaptan($CH_3SH$) was indicated to be higher concentration in previous smoker than non-smoker and smoker(p<0.05), smoking for over 20 years was higher than the under 20 years group(p<0.05). The group of drinking over 5 times a week was indicated to have higher concentration than the under once-twice a week group(p<0.01). The group of not toothbrushing before going to sleep had higher concentration than the group of toothbrushing before going to sleep(p<0.05). The group of scaling sometimes was indicated to have higher concentration than the group of scaling regularly(p<0.05). dimethyl sulfide($(CH_3)_2S$) was indicated to be higher concentration in the group with over 2 bottles of Soju than in the group with under 1 bottles of Soju(p<0.01). The regular scaling will need to be carried out in the preventive dimension for managing oral malodor. The guidance on non-smoking and moderation in drink will need to be surely included.

• Journal of dental hygiene science
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• v.16 no.6
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• pp.472-480
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• 2016

In this study, 110 adults aged 40 to 69 years were surveyed from April 28, 2016, to May 28, 2016 to analyze their periodontal status according to daily stress, coping methods, and oral health behavior. The collected data were analyzed using the t-test, one-way analysis of variance, and hierarchical multiple regression. Daily stress levels of all subjects were most frequent potential risk 64.5% of the subjects, the high risk 19.1% and 16.4% of the health group. Regarding stress coping methods, active methods recorded 2.46, passive methods recorded 2.32. Regarding oral health behaviors, subjects brushed an average of 2.45 times daily, for an average of 2 minutes. Futhermore, 69.1% of subjects brushed before bedtime and 89.1% practiced scaling. Regarding periodontal status, the O'Leary index was 73.45, gingivitis index was 1.30, an average of 2.83 quadrants possessed a periodontal pocket. The hierarchical multiple regression analysis identified, type of employment (${\beta}=-0.348$), scaling (${\beta}=-0.253$), and age (${\beta}=0.244$) as factors that influence the number of quadrants possessing a periodontal pocket. These results confirmed that the oral health behavior of scaling, but not stress levels of coping methods, strongly influenced periodontal status.