• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.4
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• pp.264-274
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• 2003

This paper presents a direct generalized minimum-variance self tuning controller with a PID structure using neural network which adapts to the changing parameters of the nonlinear system with nonminimum phase behavior, noises and time delays. The self-tuning controller with a PID structure is a combination of the simple structure of a PID controller and the characteristics of a self-tuning controller that can adapt to changes in the environment. The self-tuning control effect is achieved through the RLS (recursive least square) algorithm at the parameter estimation stage as well as through the Robbins-Monro algorithm at the stage of optimizing the design parameter of the controller. The neural network control effect which compensates for nonlinear factor is obtained from the learning algorithm which the learning error between the filtered reference and the auxiliary output of plant becomes zero. Computer simulation has shown that the proposed method works effectively on the nonlinear nonminimum phase system with time delays and changed system parameter.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.3-12
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• 2016

Recently, the study on 5G mobile communication systems using the millimeter-wave frequency band have been actively promoted and the importance of compensation of the nonlinearity of power amplifier caused by the characteristics of millimeter-wave frequency propagation attenuation is increasing. In the paper, we propose a piecewise polynomial model based on subdivision coefficient which are characteristics of power amplifier separated linear section and a non-linear section. In addition, the structure of digital predistortion based on the proposed model and direct learning method are proposed to implement a digital predistortion. To verify the proposed model, digital predistortion based on the proposed model and direct learning method for 60 GHz power amplifier using LTE signal implemented in the FPGA. And the hardware test bench measured performance and complexity. The proposed model achieves 3.3 dB gain over the single polynomial model in terms of the ACLR and reduces 7.5 percent in terms of the complexity.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.4
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• pp.113-127
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• 2015

An interface in smart device environment is changing to TUI(touch user interface) environment where a system is being controlled by physical touch, differently from a system controlled through conventional mouse and keyboard. What is more important than anything else in this TUI environment is to implement interface in consideration of learn ability and cognitive constructivism according to user's experience. Therefore, now is the time when it is necessary to carry out various studies on smart content design process going a step farther together with discussing the details of user's experience factor. Hence, this study was intended to look into what effect a user's experiential traits had on the production of contents for the purpose of measures for improving TUI user satisfaction in order to effectively realize contents in smart environment. Results were yielded by using a statistical empirical analysis such as cross-tabulation analysis according to important variable and user, paired t-test, multiple response analysis, and preference frequency analysis of user preference on the basis of a survey. As a result, a system was presented for implementing DFSS(Design For Six Sigma) process. TUI experience factor can be divided into direct habitual experience, direct learning experience, indirect habitual experience, and indirect learning experience. And in the results of study, it was possible to find that the important variables of this study had a positive effect on the improvement of use satisfaction with contents on the whole according to the user convenience of smart contents. This study is expected to have a positive effect on efficient smart device-based contents production by providing objective information according to empirical analysis to smart media-based developer and designer and presenting a model for improving the changed TUI usability.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.33-40
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• 2023

As South Korea enters the realm of an super-aging society, the demand for elderly welfare services has been steadily rising. However, the current shortage of welfare personnel has emerged as a social issue. To address this challenge, there is active research underway on elderly care robots designed to mitigate the social isolation of the elderly and provide emergency contact capabilities in critical situations. Nonetheless, these functionalities require direct user contact, which represents a limitation of conventional elderly care robots. In this paper, we propose a solution to overcome these challenges by introducing a care robot system capable of interacting with users without the need for direct physical contact. This system leverages commercialized elderly care robots and cameras. We have equipped the care robot with an edge device that incorporates facial expression recognition and action recognition models. The models were trained and validated using public available data. Experimental results demonstrate high accuracy rates, with facial expression recognition achieving 96.5% accuracy and action recognition reaching 90.9%. Furthermore, the inference times for these processes are 50ms and 350ms, respectively. These findings affirm that our proposed system offers efficient and accurate facial and action recognition, enabling seamless interaction even in non-contact situations.

• Journal of the Korean Society of Earth Science Education
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• v.12 no.3
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• pp.184-197
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• 2019

The purpose of this study is to explore needs and the direction for the development of localization data in the geological field of elementary school. Many studies show that geology-related learning is highly effective in the form of direct learning, and It is reported that this learning has a positive effect on students' scientific attitudes. As such, the first-hand experience of the geological learning is outdoor geology learning and is the basis and core of the development of localization materials. However, the analysis of this study shows that the development of outdoor geology learning site is mainly conducted in some regions. In addition, considering that geological sites are distributed evenly throughout Korea, it is necessary to actively develop geological-related localization materials to learn elementary school geology-related units. In addition, some areas where outdoor geological study grounds were developed are composed only of learning places and no specific learning materials have been developed. In this regard, not only geological researchers but also field teachers working in the area need much effort. Development of localization material in the geological field needs to be developed at the level of material presented in the geology unit of the textbook. And in the actual class, it is desirable to use the textbook data and the developed localization data at the same time. In addition, the development of the outdoor geology field should be developed in consideration of the pre-experience-post activities so that learners can have various geological experiences.

• Journal of Convergence for Information Technology
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• v.11 no.12
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• pp.138-147
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• 2021

This study aims to analyze the characteristics and preferences of learners who participated in college online classes for effective online learning. A total of 101 college students who participated in online classes completed the survey including personal characteristics of students and learning factors that affect online classes. The results showed that male students were more likely than female students to respond that online classes were more effective. Likewise students who learned from video recordings compared to those who learned from real-time lectures. As a result of analyzing the difficulties of online learning, there was a high probability that online learning was ineffective for students who had difficulties in self-learning and asking questions to their lecturers. Likewise, students who spent a lot of time studying online lectures, there was a high probability that online classes would be more effective for students who spent a lot of time on assignments. The results suggest that online learning is more effective for students who learn actively and self-directedly than those who passively participate in classes. This study implies that it is necessary to design online classes based on the characteristics and preferences of learners to improve the quality of education.

• Journal of vocational education research
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• v.36 no.4
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• pp.1-20
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• 2017

The purpose of this study is to identify the cognitive and psychological precedence factors of career preparation behaviors of university students and to clarify the structural relationships between the variables. First, the effects of reflective learning on university students' career preparation behaviors were examined and the mediating effect of grit between reflective learning and career preparation behavior was verified. The research analyzed 307 university students in the 3rd and 4th year. The results of the study have shown that the reflective learning had a significant positive relationship with all variables of grit and career preparation behavior, but non-reflective learning have an insignificance relationship with all the main variables. In addition, reflective learning has a direct positive effect on career preparation behavior, and grit has a mediating effect on the relationship between reflective learning and career preparation behavior. The results of this study indicate that the more original variables are further identified and extended to improve career preparation behaviors of university students. It is significant that they are provided with the basic data for the development of career and job preparation education programs that can be applied in the university education field. In addition, it has been confirmed that it is important for university students to improve their ability to critically reflect on themselves, their surroundings and circumstances in order to keep them engaged and to maintain their interests. Moreover, higher education institutions should provide fundamental and extensible method of practice and educational environment.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.1
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• pp.64-73
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• 2011

Oil price prediction is an important issue for the regulators of the government and the related industries. When employing the time series techniques for prediction, however, it becomes difficult and challenging since the behavior of the series of oil prices is dominated by quantitatively unexplained irregular external factors, e.g., supply- or demand-side shocks, political conflicts specific to events in the Middle East, and direct or indirect influences from other global economical indices, etc. Identifying and quantifying the relationship between oil price and those external factors may provide more relevant prediction than attempting to unclose the underlying structure of the series itself. Technically, this implies the prediction is to be based on the vectoral data on the degrees of the relationship rather than the series data. This paper proposes a novel method for time series prediction of using Semi-Supervised Learning that was originally designed only for the vector types of data. First, several time series of oil prices and other economical indices are transformed into the multiple dimensional vectors by the various types of technical indicators and the diverse combination of the indicator-specific hyper-parameters. Then, to avoid the curse of dimensionality and redundancy among the dimensions, the wellknown feature extraction techniques, PCA and NLPCA, are employed. With the extracted features, a timepointspecific similarity matrix of oil prices and other economical indices is built and finally, Semi-Supervised Learning generates one-timepoint-ahead prediction. The series of crude oil prices of West Texas Intermediate (WTI) was used to verify the proposed method, and the experiments showed promising results : 0.86 of the average AUC.

• Journal of Korean Library and Information Science Society
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• v.37 no.3
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• pp.173-191
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• 2006

Examinations and analysis were done to understand the digital reference services of the Teaching & Learning Aid Centers under 16 metropolitan city and provincial offices of education. The data used were collected from July 3. 2006 to July 15. 2006 by the direct contacts on their main homepages and recording the question and answer transcripts. It was proven that 13 of the 16 Teaching & Learning Aid Centers have done the reference services. In this study, several characteristics-whether the digital reference service was done or not, interface access level, its title, its communication tool, reference question number, reference question style, answer rate, etc-were analyzed. Tips for the future development were provided on the basis of the inadequacies and other findings revealed through this study.

• The Journal of the Korea Contents Association
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• v.15 no.4
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• pp.545-555
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• 2015

We investigated the influence of negative emotion such as state-trait anxiety and depression and working memory (WM) on Foreign Language Vocabulary Learning (FLVL) of South Korean university students. Also, its implications for developing contents for FLVL were discerned. To do so, state-trait anxiety and depression inventories as well as four kinds of WM test were performed for 132 undergraduate students. Participants also had two semantic learning sessions for Swahili words. The mean scores of negative emotions were normal level. The results of structural equation modeling (SEM) showed that there was no effect of negative emotion on FLVL, while direct effects of the negative emotion on WM and the WM on FLVL were significant. Such results suggested that FLVL would be weakened, with the result that WM had been impaired by negative emotions. These outcomes suggested that when developing FLVL content for university students, it is necessary to consider the negative emotions of foreign language learners and to develop the contents for FLVL in the light of WM load.