• Korean Journal of Radiology
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• v.24 no.11
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• pp.1151-1163
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• 2023

Objective: To develop a deep-learning-based bone age prediction model optimized for Korean children and adolescents and evaluate its feasibility by comparing it with a Greulich-Pyle-based deep-learning model. Materials and Methods: A convolutional neural network was trained to predict age according to the bone development shown on a hand radiograph (bone age) using 21036 hand radiographs of Korean children and adolescents without known bone development-affecting diseases/conditions obtained between 1998 and 2019 (median age [interquartile range {IQR}], 9 [7-12] years; male:female, 11794:9242) and their chronological ages as labels (Korean model). We constructed 2 separate external datasets consisting of Korean children and adolescents with healthy bone development (Institution 1: n = 343; median age [IQR], 10 [4-15] years; male: female, 183:160; Institution 2: n = 321; median age [IQR], 9 [5-14] years; male: female, 164:157) to test the model performance. The mean absolute error (MAE), root mean square error (RMSE), and proportions of bone age predictions within 6, 12, 18, and 24 months of the reference age (chronological age) were compared between the Korean model and a commercial model (VUNO Med-BoneAge version 1.1; VUNO) trained with Greulich-Pyle-based age as the label (GP-based model). Results: Compared with the GP-based model, the Korean model showed a lower RMSE (11.2 vs. 13.8 months; P = 0.004) and MAE (8.2 vs. 10.5 months; P = 0.002), a higher proportion of bone age predictions within 18 months of chronological age (88.3% vs. 82.2%; P = 0.031) for Institution 1, and a lower MAE (9.5 vs. 11.0 months; P = 0.022) and higher proportion of bone age predictions within 6 months (44.5% vs. 36.4%; P = 0.044) for Institution 2. Conclusion: The Korean model trained using the chronological ages of Korean children and adolescents without known bone development-affecting diseases/conditions as labels performed better in bone age assessment than the GP-based model in the Korean pediatric population. Further validation is required to confirm its accuracy.

• The Journal of the Korea Contents Association
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• v.8 no.10
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• pp.391-400
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• 2008

The web services of the CTLs(Center for Teaching and Learning) of 30 well known Korean and foreign universities have been evaluated in the present study. The CTLs of renowned foreign universities surpass Korean CTLs in terms of manpower. Nevertheless, the web services of the renowned Korean universities' are in no way inferior to those of the foreign CTLs surveyed in the present study. We found some web services to be desired and suggested a more system oriented web service function model.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.3
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• pp.319-328
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• 2024

Semi-supervised learning is a good way to train a classification model using a small number of labeled and large number of unlabeled data. We applied semi-supervised learning to a synthetic aperture radar(SAR) image classification model with a limited number of datasets that are difficult to create. To address the previous difficulties, semi-supervised learning uses a model trained with a small amount of labeled data to generate and learn pseudo labels. Besides, a lot of number of papers use a single fixed threshold to create pseudo labels. In this paper, we present a semi-supervised synthetic aperture radar(SAR) image classification method that applies different thresholds for each class instead of all classes sharing a fixed threshold to improve SAR classification performance with a small number of labeled datasets.

• 대한공업교육학회지
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• v.32 no.1
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• pp.93-116
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• 2007

The purpose of this study was to improve the academic achievement at the public practical center of technical high school in Busan. For this study, 1 class(31 students) in the second grade at "B"technical high school were selected and these students were divided into two groups. One is the experiment group which blended learning was applied to and the other is control group which traditional lecture method was applied to. Each group was divided into three sub-groups by the level of learning ability. Non-randomized control-group pretest-posttest design was applied for this experiment planning. The subject of experiment was the unit of "3D Modeling and Making NC code" in the textbook of "Application of Automatic System" applied by the public practical center of technical high school in Busan. On-line contents were developed and applied to the blended learning to control group. In order to analyze the test result, t-test with a significance level of 0.05 was carried out using SPSS 10.0. The results of this study was summarized as follows; First, as a result of the post test performed on the experiment and the control group, there was a significant difference between two groups, that was, the blended learning was more effective than the traditional lecture method in improving academic achievement. Second, blended learning was more effective than the traditional lecture method in the group of high-leveled and middle-leveled, but was little effective on the low-leveled group. Third, blended learning was more effective than the traditional lecture method in the functional domain, but was little effective in the cognitive domain and psychomotor domain.

• Journal of Biomedical Engineering Research
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• v.39 no.5
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• pp.213-219
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• 2018

Stomach cancer is the most diagnosed cancer in Korea. When gastric cancer is detected early, the 5-year survival rate is as high as 90%. Gastroscopy is a very useful method for early diagnosis. But the false negative rate of gastric cancer in the gastroscopy was 4.6~25.8% due to the subjective judgment of the physician. Recently, the image classification performance of the image recognition field has been advanced by the convolutional neural network. Convolutional neural networks perform well when diverse and sufficient amounts of data are supported. However, medical data is not easy to access and it is difficult to gather enough high-quality data that includes expert annotations. So This paper evaluates the efficacy of transfer learning in gastroscopy classification and diagnosis. We obtained 787 endoscopic images of gastric endoscopy at Gil Medical Center, Gachon University. The number of normal images was 200, and the number of abnormal images was 587. The image size was reconstructed and normalized. In the case of the ResNet50 structure, the classification accuracy before and after applying the transfer learning was improved from 0.9 to 0.947, and the AUC was also improved from 0.94 to 0.98. In the case of the InceptionV3 structure, the classification accuracy before and after applying the transfer learning was improved from 0.862 to 0.924, and the AUC was also improved from 0.89 to 0.97. In the case of the VGG16 structure, the classification accuracy before and after applying the transfer learning was improved from 0.87 to 0.938, and the AUC was also improved from 0.89 to 0.98. The difference in the performance of the CNN model before and after transfer learning was statistically significant when confirmed by T-test (p < 0.05). As a result, transfer learning is judged to be an effective method of medical data that is difficult to collect good quality data.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.814-825
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• 2021

The purpose of this study is to analyze the effect of teaching presence on academic achievement and learning satisfaction in the university online tutoring learning environment, and to find teaching methods for students' adaption of college life and their reinforcement of learning capabilities. In the study, the relationship between teaching presence, academic achievement and learning satisfaction were analyzed for those who participants in the tutoring program of the Busan D School OO Research Center during the first semester of 2021. As a result of the study, the relationship between teaching presence, academic achievement and learning satisfaction was indicated high correlation in the order of learning management, participation management and content structure of learning activities; the effect of teaching presence on academic achievement and learning satisfaction was found a significant effect in learning management, which is a sub-area of the tutees' learning activities. These results therefore suggest the direction of the operation process and method reflecting teaching presence, and provide an in-depth discussion on the learning management method that can improve the quality of the learner's learning experience in the learning environment.

• Journal of Broadcast Engineering
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• v.28 no.3
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• pp.293-301
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• 2023

Unstandardized medical data collection and management are still being conducted manually, and studies are being conducted to classify CT data using deep learning to solve this problem. However, most studies are developing models based only on the axial plane, which is a basic CT slice. Because CT images depict only human structures unlike general images, reconstructing CT scans alone can provide richer physical features. This study seeks to find ways to achieve higher performance through various methods of converting CT scan to 2D as well as axial planes. The training used 1042 CT scans from five body parts and collected 179 test sets and 448 with external datasets for model evaluation. To develop a deep learning model, we used InceptionResNetV2 pre-trained with ImageNet as a backbone and re-trained the entire layer of the model. As a result of the experiment, the reconstruction data model achieved 99.33% in body part classification, 1.12% higher than the axial model, and the axial model was higher only in brain and neck in contrast classification. In conclusion, it was possible to achieve more accurate performance when learning with data that shows better anatomical features than when trained with axial slice alone.

• Journal of the Korean Society of School Health
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• v.23 no.2
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• pp.228-236
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• 2010

Purpose: This research was conducted to compare sex-related knowledge and attitude of 6th-grade elementary school students who participated in the field based learning and those with cooperative learning methods. Methods: The data were collected from June to July in 2009. The subjects of the study were recruited from the classes of the 6th grade conveniently assigned from the D elementary school located in Daejeon metro city. Total of 60 students were assigned either to the field based learning group, and the other 60 students to the cooperative learning group. The field based learning group received sex education at the Daejean Youth Sexuality Culture Center for 3 hours. And the cooperative learning group received sex education by cooperative learning method at the classroom for 40 minutes per session, once a week, for 3 weeks. The sex-related knowledge and attitude scales developed by Lee (2004) were used. The data were analyzed by $x^2$-test, Fisher's exact test, and t-test using the SPSS/WIN V. 12.0 program. Results: The results were as follows. 1. Sex-related knowledge was not significantly different between the cooperative learning and the field based learning group. 2. Sex-related attitude was not significantly different between the cooperative learning and the field based learning group. Conclusion: In this study, sex-related knowledge and sex-related attitude of the cooperative learning group and the field based learning group were different from the lecture method groups in the earlier study. It is worthy of notice that the cooperative learning group and the field based learning group took relatively less time to improve their knowlede and attitude than the earlier lecture based group did.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.43-54
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• 2020

The purpose of this study was to investigate the effects of participation in the learning community program on the communication skills and cooperative learning capabilities of college students. To this end, in the second semester of 2018, pre and post surveys were conducted on 296 students at A University and analyzed using SPSS. The main research results are as follows. First, there was a significant difference in the participation of the learning community program in the cooperative learning capacity of college students. Second, in the analysis by sub-factors, there were significant differences before and after the program in the factors of cooperative learning competency learning participation and learning satisfaction. Third, the differences between grades showed significant differences between the 2nd and 3rd grades before and after the program. Fourth, based on the results of this study, suggestions were made for learning community program activities and follow-up studies. The results of this study analyzed the effects of learning community activities conducted at universities on the communication skills and cooperative learning capabilities of college students, and presented practical measures for the systematic operation and support of learning community activities.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.437-442
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• 2023

The purpose of this study is to verify the effect of gamification-based classes on the learning motivation and learning immersion of junior college students and to explore the meaning. This study was conducted on 80 students from two departments as part of the teaching and learning community activities supported by the D University Teaching and Learning Development Center in Busan. The research problem of this study is, first, does gamification-based classes affect the strengthening of learning motivation of junior college students? Second, does gamification-based classes affect the learning immersion of junior college students?. As a result of conducting a survey before and after the application of gamification-based classes and examining the effectiveness, gamification-based classes showed statistically significant changes in all categories of learners' learning motivation, learning immersion. Through this, it can be seen that gamification-based classes are valuable as teaching and learning methods suitable for improving the learning motivation and learning immersion of junior college students.