• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1254-1264
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• 2008

This paper suggests an extended memory polynomial model that improves accuracy in modeling memory effects of RF power amplifiers(PAs), and verifies effectiveness of the suggested method. The extended memory polynomial model includes cross-terms that are products of input terms that have different delay values to improve the limited accuracy of basic memory polynomial model that includes the diagonal terms of Volterra kernels. The complexity of the memoryless model, memory polynomial model, and the suggested model are compared. The extended memory polynomial model is represented with a matrix equation, and the Volterra kernels are extracted using least square method. In addition, the structure of digital predistorter and digital signal processing(DSP) algorithm based on the suggested model and indirect learning method are proposed to implement a digital predistortion linearization. To verify the suggested model, the predicted output of the model is compared with the measured output for a 10W GaN HEMT RF PA and 30 W LDMOS RF PA using 2.3 GHz WiBro input signal, and adjacent-channel power ratio(ACPR) performance with the proposed digital predistortion is measured. The proposed model increases model accuracy for the PAs, and improves the linearization performance by reducing ACPR.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.884-889
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• 2010

Recently, a music genre classification has been studied. However, experts use different criteria to classify each of these classifications is difficult to derive accurate results. In addition, when the emergence of a new genre of music genre is a newly re-defined. Music as a genre rather than to separate search should be classified as emotional words. In this paper, the feelings of people on the basis of brightness and darkness tries to categorize music. The proposed classification system by applying VCM(Variance Considered Machines) is the contrast of the music. In this paper, we are using three kinds of musical characteristics. Based on surveys made throughout the learning, based on musical attributes(beat, timbre, note) was used to study in the VCM. VCM is classified by the trained compared with the results of the survey were analyzed. Note extraction using the MATLAB, sampled at regular intervals to share music via the FFT frequency analysis by the sector average is defined as representing the element extracted note by quantifying the height of the entire distribution was identified. Cumulative frequency distribution in the entire frequency rage, using the difference in Timbre and were quantified. VCM applied to these three characteristics with the experimental results by comparing the survey results to see the contrast of the music with a probability of 95.4% confirmed that the two separate.

• Journal of The Korean Association For Science Education
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• v.39 no.2
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• pp.279-293
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• 2019

This study investigated the effects of national science leading school programs on students' positive experiences about science (PES) and teachers' perceptions of curriculum implementation factors affecting students' PES. For this study, Test for Indicators of Positive Experiences about Science (TIPES) was administered to a total of 11,488 students from 117 national science leading schools and 1,315 students from 50 normal counterpart schools. In addition, a total of 105 teachers were given a survey asking their curriculum implementation levels and perceptions on importance and performance levels of each identified factor that was known to influence students' PES. Students' total PES scores and scores in five sub-components of PES were widely varied across science leading school program types. In general, participating teachers reported common curriculum implementation factors that most positively affected students' PES including 'science-related activities out of school,' 'student-centered research projects,' 'ICT-related materials' and 'performance assessment.' Based on these results, implications for science education were discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.28-36
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• 2022

As port structures are exposed to various extreme external loads such as wind (typhoons), sea waves, or collision with ships; it is important to evaluate the structural safety periodically. To monitor the port structure, especially the rubber fender, a fender segmentation system using a vision sensor and deep learning method has been proposed in this study. For fender segmentation, a new deep learning network that improves the encoder-decoder framework with the receptive field block convolution module inspired by the eccentric function of the human visual system into the DenseNet format has been proposed. In order to train the network, various fender images such as BP, V, cell, cylindrical, and tire-types have been collected, and the images are augmented by applying four augmentation methods such as elastic distortion, horizontal flip, color jitter, and affine transforms. The proposed algorithm has been trained and verified with the collected various types of fender images, and the performance results showed that the system precisely segmented in real time with high IoU rate (84%) and F1 score (90%) in comparison with the conventional segmentation model, VGG16 with U-net. The trained network has been applied to the real images taken at one port in Republic of Korea, and found that the fenders are segmented with high accuracy even with a small dataset.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.2
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• pp.357-377
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• 2014

The purpose of this study is to identify whether math class with clip-type contents has a significant impacts on the academic achievement and attitude of students. To answer the questions, two classes of 4th graders at Sinlim Elementary School in Gwanak-gu, Seoul were selected as subjects; they were divided into experimental group and comparative group. They were confirmed as a homogeneous group at the significance level of 0.05 during a pre-test. The findings are as follows. First, math class with clip-type contents had positive influence on the academic achievement. Second, math class with clip-type contents had positive influence on the attitude towards learning. Furthermore, proper clip-type contents for class boost their understanding and enhance their mathematical thinking with multiple views. It led to their self-confidence in learning math, developing a positive attitude towards math. The benefits of the present research can be summarized as follows. First, the math class with clip-type contents benefited both teachers and students. For teachers, it helped them boost the quality of their teaching. For students, it helped them understand the class better, improving their academic achievement. Second, the diverse, interesting contents had a positive impact on the following of the students: self-concept of math; attitude towards math; learning habits.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.631-638
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• 2017

In the age of the Fourth Industrial Revolution, lifestyle and industrial structures are faced with evolution from IT-based automation to the intelligent stage, demanding talents with software capabilities in various fields. Reflecting these demands, the government has enhanced basic software education for non-majors in elementary and secondary schools as well as universities. In this study, the software convergence education of Non-Majors is proposed to improve the general problem solving ability based on computational thinking and the software convergence ability in the field of their own by developing robot activity. The subjects of this study were 91 students, who were composed of various majors. The class was designed with computing thinking, convergence elements, and creative robot activity. The study was conducted for 13 weeks. To examine the effects of software convergence education through the creative robot activity, this study observed changes in the students' learning outcomes, satisfaction with creative robot activities, and perceptions of other disciplines after class based on pre-diagnosis surveys. The survey asked 12 questions including an understanding of the learning contents, overall satisfaction with multidisciplinary collaborative learning, understanding of other disciplines, and self-evaluation of problem solving ability through creative robot activities, which were compared with that before the class. They answered that their ability was improved.

• Journal of The Korean Association For Science Education
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• v.35 no.6
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• pp.1039-1048
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• 2015

The purpose of this study is to examine implications of pre-service science teacher training by analyzing science field integration and connection between learning content presented in 'Integrated Science' for high school students based on the 2015 revised science curriculum, and in pre-service science learning materials (textbooks) of the college of education. For this study, the 2015 revised 'Integrated Science' curriculum and 11 types of pre-service science teachers' learning materials related to physics, chemistry, biological science, and earth science were selected. The results were as follows. Most of the learning content presented in the 2015 revised 'Integrated Science' curriculum had integrated two or more science fields. Also, almost all learning content presented in the 2015 revised 'Integrated Science' curriculum were included in pre-service science teachers' education content, with educational content for chemistry introduced at the highest rate. The textbooks for pre-service science teachers had the most learning contents of 'Energy and Environment' domain of 'Integrated Science' for high school students. Accordingly, these results suggest that 'integrated science materials' should be developed for proper the curriculum implementation. Also, training courses for science teachers responsible for 'Integrated Science' are required. Furthermore, a revised curriculum for the college of education and a method to link with certification examinations for secondary school teachers are needed.

• Journal of Science Education
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• v.37 no.2
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• pp.374-388
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• 2013

The purpose of this study was to investigate pre-service physics teachers' perceptions on the physics education major curriculum. We surveyed 15 junior, and 13 senior college students of physics education major in an university in southern part of Korea. Among them, 24 participants(86 %) took the physics 1 course in high school and 22 participants(79 %) chose the physics 1 in their Korea Scholastic Aptitude Test. The responses showed that the most necessary part in pre-service students' learning was the understanding of high school level physics(36 %), and the understanding of introductory level physics(29 %). In the wish list of courses to be open, high school level physics course was ranked first among seven options by 61 % of respondents. Also, there was some concurrence among respondents in opinion of the necessity for understanding introductory physics. Students felt difficulties in understanding it especially owing to the lack of problem solving skill and comprehension. They added that the sufficient explanation of core concepts should be the first action in the innovative plan. Most participants of pre-service physics teachers hoped to have the revised major curriculum which could help their understanding of high school level or introductory level of physics. However, there was a gap of opinions between the group of students with completion of the high school physics 1 & 2 course and those with non-completion of them. The approach of changing major curriculum with consideration of learners' needs was recommended because the number of students with completion of the high school physics course would probably be decreasing rapidly under these circumstances such as the application of new national curriculum, the reduction of the number of the elective courses in Korea Scholastic Aptitude Test and so on.

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1329-1342
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• 2013

The purpose of this research was to investigate the relationship between the change of beginning teachers' beliefs about a lesson and that of teaching practice and argument-based inquiry using science writing. Participants were three science teachers (A, B, and C) from different middle schools. Classroom observation and interview data were collected and transcribed for analysis. A Summary Writing test was also administered to examine whether there was an improvement in students' learning. The results indicated that the interaction between the teachers and their students developed, which is concluded as an improvement in the teaching practice. Teacher A and B also reported that teacher-student interaction had improved. Teacher A and C came to understand that argument-based inquiry using science writing classes constituted learner-centered instruction. The result from the Summary Writing Test showed the impact of the changes in teaching practice and in teachers' awareness of students' learning as well as produced meaningfully higher scores than compared groups on the rhetorical structure of all the specific areas in teacher A's school and on the scientific concept at B and C's schools.

• Journal of The Korean Association For Science Education
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• v.23 no.5
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• pp.505-516
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• 2003

The concept of evolution is one of the most important concepts in the learning biology. However lots of students have difficulties in understanding its mechanism because their preexisted alternative concepts interrupt in gaining the correct idea of evolution. Students usually have the Larmarkian or teleological ideas of evolution. The purpose of this study is to investigate the effectiveness of an activity-centered instruction on the learner's conceptual change from misconception into the scientific concept, Darwinian one, and achievement. For the study, 162 students were sampled from a high school: 81 students for the activity-centered instruction and 81 students for traditional instruction. The result is as follows; 1) The activity-centered instruction is more effective than the traditional one in understanding the concept of Darwinian natural selection(p<.05) and in changing the students' various misconceptions of evolution into Darwinian one. 2) The activity-centered instruction concerning natural selection is more effective in their achievement(p<.01). 3) However, after both of the instructions, some students still kept the Lamarkian thoughts.