• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.121-127
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• 2017

From the perspective of commercializing rotating machines equipped with magnetic bearings, maintaining the error between the mechanical center and the magnetic center within an acceptable level is crucial. The existing method of measuring the center error is to adjust the position references that minimize the current imbalance present in levitation control outputs. However, this method can be applied only after all the components of the system are operational. In this paper, we present a new method of estimating the center error by using only the position sensors and a current source. A force model that relates the position of the rotor with the coil currents is set up. Using this model, the center error is estimated by minimizing the difference between the force angles and the contact angles measured in a pull test. The feasibility of the method is numerically and experimentally validated.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.9-14
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• 2018

This study aims to investigate an importance of Author keyword with analysis the position of author keyword. An analysis was carried out on the position of author keyword. we examined an importance of Author keyword by using degree centrality, closeness centrality, betweenness centrality, eigenvector centrality. In the next stage, we performed analysis on correlation between network centrality measures and the position of keyword. As a result, degree centrality, closeness centrality, betweenness centrality, eigenvector centrality both has a high value in 4th author keyword order. eigenvector centrality was the comparatively effective method to separate of author keyword order method than other 3 centrality. Correlation analysis result shows that the network analysis value are increasing in order. This study has significance in that it was able to examine the author keyword behavior. Future research is needed to identify and supplement future situational factors, behavior, and psychology.

• The KIPS Transactions:PartB
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• v.12B no.5 s.101
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• pp.561-566
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• 2005

This paper presents a visual tracking algorithm for the golf swing motion analysis by using the information of the pixels of video frames and movement of the golf club to solve the problem fixed center point in model based tracking method. The model based tracking method use the polynomial function for trajectory displaying of upswing and downswing. Therefore it is under the hypothesis of the no movement of the center of gravity so this method is not for the amateurs. we proposed method using the information of pixel and movement, we first detected the motion by using the information of pixel in the frames in golf swing motion. Then we extracted the club head and hand by a properties of club shaft that consist of the parallel line and the moved location of club in up-swing and down-swing. In addition, we can extract the center point of user by tracking center point of the line between center of head and both foots. And we made an experiment with data that movement of center point is big. Finally, we can track the real trajectory of club head, hand and center point by using proposed tracking algorithm.

• Journal of Digital Convergence
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• v.18 no.2
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• pp.47-56
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• 2020

The purpose of this study was to identify the research trends and characteristics of existing research related to the AEO system. The methodology of the study was to utilize the Degree Centrality, Closeness Centrality and Betweenness Centrality presented by the Social Network Analysis (SNA). Keyword network analysis results showed that "MRA", "Logistics Security" were derived from the Degree Centrality results, "MRA", "Logistics Security" from the Closeness Centrality results, and, as a result of the Betweenness Centrality, "AEO Utilization Benefits" and "reliability" were derived from the top keyword results. The analysis of differences in centrality by period also confirmed that trends in research have changed based on specific time points. This study has implications for the study in that it presented worldwide research trends through keyword network analysis of the AEO system.

• Smart Media Journal
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• v.9 no.2
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• pp.9-15
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• 2020

In this paper, we propose a network model composed of Multi path Encoder-Decoder branches that can recognize each instance from the image. The network has two branches, Dot branch and Segmentation branch for finding the center point of each instance and for recognizing area of the instance, respectively. In the experiment, the CVPPP dataset was studied to distinguish leaves from each other, and the center point detection branch(Dot branch) found the center points of each leaf, and the object segmentation branch(Segmentation branch) finally predicted the pixel area of each leaf corresponding to each center point. In the existing segmentation methods, there were problems of finding various sizes and positions of anchor boxes (N > 1k) for checking objects. Also, there were difficulties of estimating the number of undefined instances per image. In the proposed network, an effective method finding instances based on their center points is proposed.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.269-280
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• 2006

The purpose of this study is to establish the concept of the evidence-based pediatric dentistry and to investigate the application methods of it. The definition of the evidence-based pediatric dentistry was suggested as 'the integration of the best scientific research evidence with the professional expertise of pediatric dentist and the value of pediatric patients and their caregivers in dental practice for the child and adolescent'. The methods of practising evidence-based pediatric dentistry were investigated, the recent conclusions of the evidence-based pediatric dentistry were summarized by topics, the research methods of systemic review and clinical practice guidlines were analyzed, and the individual research methods as randomized controlled trials were investigated. The author proposed increasing the understanding and consensus of the necessity of evidence-based pediatric dentistry, education about the evidence-based pediatric dentistry, computerization of all published articles of Korean pediatrtic dentistry, continuing research and popularization of systemic research and clinical practice guidlines, production of Korea's own evidences of pediatric dentistry, and the improvement of soical environment of pediatric practice.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.181-181
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• 2018

설계홍수량 산정 시 지점확률강우량을 대상유역 내 면적강우량으로 환산하기 위하여 면적우량 환산계수(areal reduction factor, ARF)를 적용한다. ARF 산정방법은 크게 면적고정형 방법과 호우중심형 방법으로 나뉜다. 면적고정형 방법은 현재 국내 하천설계기준에서 설계강우량 산정 시 활용하고 있는 방법이지만, 동 시간에 발생한 강우사상을 활용하지 않고 지점강우량과 면적강우량의 독립적인 빈도해석을 통해 산정되므로 비현실적인 값이라고 볼 수 있다. 본 연구에서는 강우사상의 공간분포 특성을 효과적으로 반영할 수 있는 레이더 강우 자료를 활용하여 한강권역의 호우중심형 ARF를 활용하였다. 호우중심형 ARF는 지속기간 1, 3, 6, 12, 24시간에 대하여 산정하였으며, 재현기간은 강우 사상의 규모에 따라 총 다섯 구간(0-10, 10-20, 20-50, 50-80, 80-100년)으로 분류하였다. 지속기간 및 재현기간에 따른 호우중심형 ARF는 강우 사상마다 산정되므로 다양한 값이 산재(scattered)되어 있는데, 대푯값을 선정하기 위하여 Weibull 분포의 비초과확률 95%의 값을 추출하였다. 두 가지 방법으로 산정된 ARF는 지속기간에 대하여 로그형태로 증가하였으나, 재현기간에 따른 관계에서는 차이를 보였다. 면적고정형 ARF는 재현기간에 대한 민감도가 매우 낮았으나, 호우중심형 ARF는 재현기간에 따라 감소하였다. 또한 호우중심형 ARF는 지속시간이 길수록 재현기간에 대한 민감도가 점차 낮아졌으며 지속기간 24시간 이후로는 일정한 값을 보였다. 이러한 차이는 레이더 실 강우를 활용한 호우중심형 ARF 산정 시에 면적고정형 ARF 산정과정에서 고려되지 않는 강우의 시 공간적 특성을 반영하기 때문인 것으로 사료된다. 따라서 설계홍수량 산정 시 호우중심형 ARF를 적용한다면 보다 현실적인 값을 제시할 수 있을 것으로 판단된다.

• Journal of Korea Port Economic Association
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• v.38 no.4
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• pp.25-43
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• 2022

Unlike the past, efforts must be made to interpret physical distribution from a network perspective as the service area expands spatially. In addition, logistics networks are undergoing rapid changes due to various changes in the environment. Therefore, the purpose of this study is to analyze the changes in the structure of maritime cargo and the centrality of ports using social network analysis. Using the trade data of domestic maritime at five-year intervals, we investigated changes in the network structure and identified the main factors that affect the centrality of domestic ports. Ports with the highest centrality, which is seen as a port that plays the role of an intermediary, emerged in the order of Busan and Ulsan. This study predicts patterns of domestic cargo trade over the next 20 years based on changes in port centrality and understanding of maritime cargo network, and can be used as reference materials for risk preparation.

• Journal of the Korean School Mathematics Society
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• v.22 no.4
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• pp.369-393
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• 2019

The purpose of this study is to find the commonality between process-focused assessment and existing performance evaluation and to find out whether the process-focused assessment is effective for the development of the character of school mathematics. By analyzing the previous research, this study defined the meaning of process-focused assessment as an evaluation that can improve students' growth and quality of class through immediate feedback by introducing various performance tasks and evaluation methods. The character of school mathematics refers to personality factors that are easily expressed and cultivated during math classes. Therefore, this study presented examples of the feasibility of process-focused assessment focusing on geometry and vector subjects and examined the effectiveness of mathematics and character development through process-based evaluation. Four course-based assessments (math experiments, logic, proof, and communication) aimed at cultivating the character of school mathematics were conducted from March to June 2019 for the third year of high school. The index was measured. Analysis of the results using the corresponding variable t-test showed that the process-based evaluation in this study had a significant effect on the character of school mathematics development.

• Journal of Science Education
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• v.44 no.2
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• pp.133-144
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• 2020

As a part of the second-year monitoring study on the implementation of the 2015 revised science curriculum in middle schools, this study focuses more on examining middle school science teachers' perceptions on the process-based assessment (PBA). A total of 105 middle school science teachers (44 teachers from science leading schools, 61 teachers from ordinary schools) responded to the survey questionnaire, and 16 teachers participated in interviews. The results include teachers' perceptions on the changes in their teaching and assessment methods, some challenges of implementing PBA, and educational implications of PBA. Survey results indicate that the teachers perceived themselves using more PBA methods after the 2015 revised science curriculum was launched. The teachers in science-leading schools present statistically higher average scores to the items on the PBA utilization than the ones in ordinary schools. However, the teachers felt confused in conceptually differentiating PBA from prior performance-based assessment. They also experienced some conflicts when implementing PBA under the achievement-oriented school atmospheres. In addition, they often faced difficulties in securing objectivity and reliability of PBA and felt the burden of evaluating individual students. This study suggests the necessity of giving more authority and trust to science teachers regarding PBA, constructing more supportive environment to cultivate teacher competency as evaluation experts, and the need to reduce task burden. However, some teachers who actively implemented PBA express some level of satisfaction as observing students' positive reaction to PBA.