• Proceedings of the IEEK Conference
• /
• 2000.06e
• /
• pp.13-16
• /
• 2000

This paper presents a simple class-D stereo amplifier using 3-phase full bridge circuit configurations which is controlled by a new current control switching method. Although this class-D amplifier has an only one current control loop with the proposed switching method, a good performance can be obtained. In this paper, a strategy for driving stereo signal amplifier with 3-phase full bridge is discussed. With the experimental results, usefulness of the proposed amplifier is confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.8C
• /
• pp.772-781
• /
• 2009

This paper proposes a novel algorithm for the efficient classification and retrieval of medical images. After color and edge features are extracted from medical images, these two feature vectors are then applied to a multi-class Support Vector Machine, to give membership vectors. Thereafter, the two membership vectors are combined into an ensemble feature vector. Also, to reduce the search time, Correlated Categories Vector is proposed for similarity matching. The experimental results show that the proposed system improves the retrieval performance when compared to other methods.

• Proceedings of the KACD Conference
• /
• 2003.11a
• /
• pp.564-564
• /
• 2003

In recent years, the use of Microtomograph in dentistry were proposed and its applications are increasing. The purposes of this study is to evaluate the micro leakage in Class V restorations by using Microtomograph and to compare with other leakage test methods. Using high speed round bur, Class V cavities were prepared to the buccal sides of sixty extracted human upper premolars and randomly distributed to 4 experimental groups and restored as follows.(중략)

• Restorative Dentistry and Endodontics
• /
• v.7 no.1
• /
• pp.131-138
• /
• 1981

The purpose of this study was to evaluate the marginal leakage of composite resin. Preparing 144 class V cavities on freshly extracted noncarious teeth, composite resins were prepared and inserted by one dentist according to the manufacturer's instructions. The experiments were performed in two different groups; In group I; Class V cavities with $90^{\circ}$ cavosurface angle, In group II; Class V cavities with $135^{\circ}$ cavosurface angle. And each group was divided 2 subgroups; In control group; composite resin restoraions without acid etch technique. In experimental group; composite resin restorations with acid etch technique. All specimens were immersed in 0.05% crystal violet solution. Before examination, the restored teeth were subjected to thermal stress. The specimens were sectioned occlusogingivally through the center of the restorations with a diamond disk. The sections were examined under a reflected light microscope at 1 day, 7 days and 30 days after immersing the specimens in dye solution. The results were as follows; 1. Control group of group I and group II showed marginal leakage. 2. The degree of marginal leakage in experimental group was greater reduced than control group. 3. In control group, the degree of marginal leakage in group I was greater than group II. 4. In experimental group, there is not statistical differences of the degree of marginal leakage between group I & group II.

• Journal of The Korean Association For Science Education
• /
• v.24 no.6
• /
• pp.1094-1105
• /
• 2004

The effects of learning using Information Communication Technology(ICT) on the students' scientific inquiry ability and science-related affective characteristics were analyzed in Earth History and Crust Movement units of science textbook for eighth graders. For this study, two classes of middle school second students in Chung-nam were selected and taught for six week under different teaching methods. One class is the test class taught with ICT applied teaching materials and the other class is the control class instructed by a conventional method. One week before the experiment, both classes were given tests on scientific inquiry ability and science-related affective characteristics, and they were tested again after the experiment. The results of scientific inquiry test showed statistically meaningful differences in the experimental class and the control class. The experimental class showed statistically meaningful difference in scientific inquiry test. Science-related affective characteristics test showed no statistically meaningful difference in the experimental class. Among three scientific science-related affective characteristics, especially the one fields of interests showed statistically meaningful differences which suggest that learning using ICT has a positive effect on the expanding of students' science-related affective characteristics.

• The Journal of the Korea Contents Association
• /
• v.20 no.1
• /
• pp.233-244
• /
• 2020

The purpose of this study is to explore this music class activity and its effectiveness based on design thinking and using applications class. To this end, the effectiveness study was conducted based on the researchers' prior study of 'Development of Music learning program Using Applications Based on Design Thinking'. Under the study, two first graders who are attending P Middle School in Gyeonggi Province were selected as experimental(29) and control groups(29). The experimental group conducted the class using this program and the control group conducted a general music class. The pre-post-examination was conducted to find out the effects of this class on students' creativity, empathy, teamwork, and problem-solving skills. The course of the study was developed for seven weeks, a program pre-post-survey, and a response sample t-test was used to analyze the results. The study found that experimental groups show significant differences in creativity, empathy, cooperative spirit and problem-solving skills, while control groups that conducted general music classes had similar results in advance-postmortem. The group's students found that their ability to empathize with others in the problem situation was enhanced, their sense of rapid problem solving and achievement was high, and their ability to create creative ideas and enhance creativity in the process of solving the problem was improved. In the future, we look forward to using this music class activity in the field where new, creative, and diverse classroom models are needed.

• Progress in Superconductivity and Cryogenics
• /
• v.5 no.3
• /
• pp.48-51
• /
• 2003

HTS power transmission cable is expected to transport large electric power with a compact size. We are developing a 3-core, 22.9 kV, 50 MVA class HTS power cable, and each core consists of a conductor and shield wound with Bi-2223 tapes, electrical insulation with laminated polypropylene paper (LPP) impregnated with liquid nitrogen. This paper describes the design and experimental results of the model cable for the 22.9 kV, 50 MVA class HTS power transmission cable. The model cable was used the SUS tapes instead of HTS tapes because of testing the electrical characteristics only. The model cable was 1.3 m long and electrical insulation thickness was 4.5 mm. The model cable was evaluated the partial discharge (PD), AC and Impulse withstand voltage in liquid nitrogen. The AC and Impulse withstands voltage and PD inception stress was satisfied with the standard of Korea Electric Power Corporation (KEPCO) in the test results. The 3-core 22.9 kV, 50 MVA class HTS power cable has been designed and manufactured based on these experimental results.

• Journal of Institute of Control, Robotics and Systems
• /
• v.19 no.4
• /
• pp.364-371
• /
• 2013

Emotion Recognition is one of the important part to develop in human-human and human computer interaction. In this paper, we have focused on the performance of multi-class SVM (Support Vector Machine) with Gaussian RFB (Radial Basis function) kernel, which has been used to solve the problem of emotion recognition from physiological signals and to improve the accuracy of emotion recognition. The experimental paradigm for data acquisition, visual-stimuli of IAPS (International Affective Picture System) are used to induce emotional states, such as fear, disgust, joy, and neutral for each subject. The raw signals of acquisited data are splitted in the trial from each session to pre-process the data. The mean value and standard deviation are employed to extract the data for feature extraction and preparing in the next step of classification. The experimental results are proving that the proposed approach of multi-class SVM with Gaussian RBF kernel with OVO (One-Versus-One) method provided the successful performance, accuracies of classification, which has been performed over these four emotions.

• Journal of Korean Elementary Science Education
• /
• v.32 no.3
• /
• pp.225-238
• /
• 2013

The purpose of this study is to find out The Effects of the Learning Motive, Interest and Science Process Skills using the 'Light' Unit on Science-based STEAM. As the subject, 2 classes in the 6th grade of G elementary school located in Busan were selected. Through the pre/post inspection design between experiment and comparison class, the units of science courses in the first semester of 6th grade '1. Light' were applied. The results were as follows: Firstly, it was observed that it would have a meaningful effect to improve the learning motive of students who performed STEAM education. Secondly, it was observed that it would have a meaningful effect to improve the interest of students who performed STEAM education. Especially, the results of 'attention', 'relevance', 'confidence' and 'satisfaction' in the experimental class were higher than those of students in the comparative class. The experimental class gave a positive effect on the 'attention', 'confidence' and 'satisfaction'. According to statistical analysis, this result is meaning. Thirdly, the test on science processing skills showed that there was not statistic meaningful differences between the two groups. But, in the sub-parts, there was statistic meaningful differences between the two groups on the 'integrated inquiry ability'.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.2
• /
• pp.346-351
• /
• 1997

The creep characteristics of an Al-5wt.% Ag alloy including the stress exponent, the activation energy for creep and the shape of the creep curve were investigated at a normalized shear stress extending from $ 10^{-5}{\;}to{\;}3{\times}10^{-4}$ and in the temperature range of 640-873 K, where silver is in solid solution. The experimental results shows that the stress exponent is 4.6, the activation energy is 141 kJ/mole, and the stacking fault energy is $180{\;}mJ/m^2$, suggesting that the creep behavior of Al-5 wt.% Ag is similiar to that reported for pure aluminum, and that under the current experimental conditions, the alloy behaves as a class II(metal class). The above creep characteristics obtained for Al-5 wt.% Ag are discussed in the light of prediction regarding deformation mechanisms in solid solution alloys.