• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.400-403
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• 2007

This research describes how the class D amplifiers with power efficiency are designed and implemented for the PA audio systems. The configuration that makes use of the class D amplifier properties depends strongly on their applications. Thus in this paper the characteristics of the 2-level and 3-level PWM are analysed and the circuit implementation for them is presented. Using the proposed methods, they are designed and simulated for the further investigation. Test(Simulation) results present the improved performance that shows the satisfactory operations in controlling the PWM to the input signals.

• Journal of the Korean Data and Information Science Society
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• v.18 no.4
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• pp.1045-1056
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• 2007

We consider M/M/1 feedback queues with multi-class customers. We assume that different classes of customers have different arrival rates, service rates and feedback probabilities. Using the h-transforms of McDonald(999) we derive an importance sampling estimator for an overflow probability that the total number of customers in the system reaches a high level before emptying.

• Journal of applied mathematics & informatics
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• v.39 no.3_4
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• pp.529-539
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• 2021

The purpose of this paper is to prove some fixed point theorems using (𝜓, 𝜑)-contractions via the concept of C-class functions in G_b-metric spaces. Moreover, an example is presented to illustrate the validity of our results.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.2037-2040
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• 2004

In this paper we introduce a new prototype based classifiers for overlapping data, where training pattern can be overlap on the feature space. The proposed classifier is based on the prototype from neural network classifier (NNC)[1] for overlap data. The method automatically chooses the initial center and two radiuses for each class. The center is used as a mean representative of training data for each class. The unclassified pattern is classified by measure distance from the class center. If the distance is in the lower (shorter radius) the unknown pattern has the high percentage of being in this class. If the distance is between the lower and upper (further radius), the pattern has the probability of being in this class or others. But if the distance is outside the upper, the pattern is not in this class. We borrow the words upper and lower from the rough set to represent the region of certainty [3]. The training algorithm to find number of cluster and their parameters (center, lower, upper) is presented. The clustering result is tested using patterns from Thai handwritten letter and the clustering result is very similar to human eyes clustering.

• Computers and Concrete
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• v.8 no.5
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• pp.583-595
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• 2011

This paper studied the cement efficiency factor (k factor) of high calcium Class F fly ash. This k factor represents a unit of fly ash with efficiency equivalent to k unit of cement. The high calcium Class F fly ash was used to replace cement in concrete. The modified Bolomey's law with linear relationship was used for the analysis of the result of compressive strength, cement to water ratio (c/w) and fly ash to water ratio (f/w) by using the multi-linear regression to determine the k factor and other constants in the equations. The results of analysis were compared with the results from other researcher and showed that the k factor of high calcium Class F fly ash depends on the fineness of fly ash, replacement level and curing age. While the amount of CaO content in Class F fly ash not evident. Furthermore, necessary criteria and variables for the determination of the k factor including the use of the k factor in concrete mix design containing fly ash were proposed.

• The Mathematical Education
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• v.55 no.3
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• pp.299-316
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• 2016

The abilities for 21st learners have recently changed and learners' engagement is emphasized. In flipped classroom, students learn the prerequisite concepts of the lecture online in advance and perform various types of activities based on interaction and engagement. As students in flipped classroom construct knowledge actively, students' engagement is very important. Therefore, I conducted a research of flipped mathematics class to help teachers to better understand students' engagement in flipped mathematics class. The flipped mathematics class was conducted for about 3 weeks with 29 middle school students and one teacher. Video and audio recordings, completed student worksheets and interview data were collected and analyzed using the qualitative method. The results of this study showed that students' engagement is influenced by diverse factors. Engagement factors were categorized by teacher factors, community factors, material factors, tasks and strategy factors, classroom culture factors. Each factor facilitates or suppresses behavioral, emotional, cognitive, agentic engagements, and sometimes several factors are related. The results of this study increase understanding of engagement through the example of a case study on flipped mathematics class.

• Journal of Species Research
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• v.7 no.3
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• pp.193-201
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• 2018

Culturable bacterial diversity was investigated using freshwater and sediment samples collected from the North Han River basin in 2017, as a part of the research program 'Survey of freshwater organisms and specimen collection'. Over a thousand bacterial strains were isolated from the samples and identified based on 16S rRNA gene sequences. Among the bacterial isolates, 22 strains showing higher than 98.7% sequence similarity with validly published bacterial species, but not reported in Korea, were classified as unrecorded species in Korea. The 22 bacterial strains were phylogenetically diverse and assigned to 6 classes, 11 orders, 15 families, and 21 different genera. At the generic level, the unreported species were affiliated with Flavobacterium of the class Flavobacteria, Flexibacter of the class Cytophagia, Blastomonas, Brevundimonas, Elstera, Rhizobium, Roseomonas, Sphingomonas, and Xanthobacter of the class Alphaproteobacteria, Albidiferax, Cupriavidus, Curvibacter, Ferribacterium, Hydrogenophaga, Iodobacter, Limnohabitans, Polaromonas, Undibacterium, and Variovorax of the class Betaproteobacteria, Pseudomonas of the class Gammaproteobacteria, and Arcobacter of the class Epsilonproteobacteria. The unreported bacterial species were further characterized by examining Gram reaction, colonial and cellular morphology, and biochemical properties. The detailed descriptions of 22 strains of the unreported bacterial species are also provided.

• The korean journal of orthodontics
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• v.48 no.6
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• pp.357-366
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• 2018

Objective: The purpose of this study was to analyze the transverse dental compensation in reference to the maxillary and mandibular basal bones using cone-beam computed tomography (CBCT) and evaluate the correlations between transverse dental compensation and skeletal asymmetry variables in patients with skeletal Class III malocclusion and facial asymmetry. Methods: Thirty patients with skeletal Class I (control group; 15 men, 15 women) and 30 patients with skeletal Class III with menton deviation (asymmetry group; 16 men, 14 women) were included. Skeletal and dental measurements were acquired from reconstructed CBCT images using OnDemand3D 1.0 software. All measurements were compared between groups and between the deviated and nondeviated sides of the asymmetry group. Correlation coefficients for the association between skeletal and dental measurements were calculated. Results: Differences in the ramus inclination (p < 0.001), maxillary canine and first molar inclinations (p < 0.001), and distances from the canine and first molar cusp tips to the midmaxillary or midmandibular planes (p < 0.01) between the right and left sides were significantly greater in the asymmetry group than in the control group. In the asymmetry group, the ramus inclination difference (p < 0.05) and mandibular canting (p < 0.05) were correlated with the amount of menton deviation. In addition, dental measurements were positively correlated with the amount of menton deviation (p < 0.05). Conclusions: Transverse dental compensation was correlated with the maxillary and mandibular asymmetry patterns. These results would be helpful in understanding the pattern of transverse dental compensation and planning surgical procedure for patients with skeletal Class III malocclusion and facial asymmetry.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.355-363
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• 2020

This study is conducted to examine the changes in class perception and career perception according to the teaching method for dental hygiene students in some areas of Gangwon-do. Using the same questionnaire, the first questionnaire was conducted after contact classes in December 2019, and the second questionnaire was conducted after non-contact classes in July 2020. Data were analyzed using SPSS Windows 24.0, and the results are as follows. There were differences in class perception and career perception according to grades, and career interest, career curiosity, and career confidence were different according to school life satisfaction and professional tooth cleaning Class satisfaction. In the case of non-contact classes, the proportion of career decisions through the internet increased, and career confidence also increased. These results can be provided as basic data necessary for the use of methods such as flip-learning classes in consideration of the convergence aspect in the practical subject class management and for the production of standardized practical videos for practical tests.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.375-384
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• 2015

This study is aimed at analyzing class participation value of the students who participate in physical education class implemented by university, and inquiring into the convergence relations between students-perceived class participation propensity and participatory behavior. In an effort to verify hypotheses consequent on this research objectives, this study conducted confirmatory factor analysis, reliability analysis, correlation analysis, and structural equation model analysis using PASW 18.0 and AMOS 18.0. The concrete results of this research are as follows: First, the class participation value of the students participating in general physical education was found to have an influence on participatory propensity. Second, the participatory propensity of the students participating in general physical education was found to have an influence on class participation behavior intention.