• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.05a
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• pp.77-86
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• 2005

컨테이너 터미널에서는 장치장으로 반입되는 수출 컨테이너의 무게를 몇 단계 그룹으로 나누고 각 무게그룹 별로 모아서 장치한다. 이는 수출 컨테이너를 선박에 싣는 적하 작업 시 선박의 안정성을 위하여 무거운 무게그룹의 컨테이너들을 장치장에서 먼저 반출하여 선박의 바닥 쪽에 놓기 위함이다. 하지만 반입되는 컨테이너의 무게그룹을 결정할 때 사용하는 운송사로부터 받은 무게정보는 부정확한 경우가 많아 하나의 스택(stack)에 서로 다른 무게그룹에 속하는 컨테이너들이 섞이게 된다. 이로 인하여 무거운 무게그룹의 컨테이너를 반출할 때 해당 컨테이너의 상단에 놓여진 보다 가벼운 무게그룹의 컨테이너들을 임시로 옮겨야 하는 재취급(rehandling, reshuffling)이 발생하게 된다. 적하작업 시 장치장에서 재취급이 빈번히 발생하면 작업이 지연되므로 터미널 생산성 향상을 위해서는 재취급 발생을 가급적 줄여야 한다. 본 논문에서는 기계학습 기법을 적용하여 반입 컨테이너의 무게그룹을 보다 정확히 추정하는 방안을 제안한다. 또한 탐색을 통하여 분류기 생성에 관여하는 비용행렬(cost matrix)을 조정함으로써 재취급 발생을 줄일 수 있는 분류기(classifier)를 생성하는 방안을 함께 소개한다. 실험 결과 본 논문에서 제안하는 방안 적용 시 재취급 발생을 $5{\sim}7%$ 정도 줄일 수 있음을 예상할 수 있었다.

• Journal of Educational Research in Mathematics
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• v.15 no.3
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• pp.335-352
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• 2005

In this paper, we consider a center of gravity of convex polygon which could be an enriched topic for the gifted in mathematics(7th grades) and suggested a case that the gifted experienced a center of gravity. Based on properties of Archimedes' center of mass, we define it as a point which make a polygon be in counterpoised with its area and explain how to find that point through using integral calculus or internal division. Then we consider that the gifted would experience various kinds of mathematical thinking and apply diverse ways of problem solving 3s searching for this topic. As this research, the teacher would be able to conduct the gifted with penetration into center of gravity and to let them participate in advanced learning courses which value ma-thematical thinking while they undergo similar experiences such as mathematicians.

• Journal of Educational Research in Mathematics
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• v.24 no.3
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• pp.333-357
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• 2014

This study resulted from a study regarding creative STEAM System based upon an experiment with the center of gravity. The results of the study are constructed by a fusion of mathematics and physics, showing that they are the same as mathematical calculations. Also, students can find that center of gravity of an object is in equilibrium on a metal rod when the center of gravity exactly is placed on the rod. The fact that an experimental results are correspond to calculations can maximize the effectiveness of teaching. And also this study has the following effectiveness. First, the exact construction and calculations arouses good competition among students. Second, this experiment can give students a motivation for study and increase their thinking in classes because the theoretical background of center of gravity experiment is basically attributed to math and science classes in school. This study includes three different types of center-of-gravity experiments. One is a simple type of experiment in which center of gravity exists inside of an object. Another is a complicated one in which the center of gravity is also inside of an object. However, the third type is an experiment in where the center of gravity is outside of an object. Therefore, it gives students an opportunity to discuss how to confirm equilibrium on a metal rod when the object has its center of gravity outside. Having discussions in class will allow students to have a critical way of thinking. In addition, searching for a way to solve a problem will increase creativity of students as well. And the last type is finding the center of gravity of a big acrylic panel where multiple objects are on the panel. According to the survey and interview conducted by students who participated in this program, teaching based on creative STEAM system helps students to get a better understanding and more fast acquisition of knowledge. We can expect that a well-planned creative STEAM system through a continuous study will be both effective and efficient in educating critical and creative students.

• Journal of the Korea Computer Graphics Society
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• v.26 no.2
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• pp.11-19
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• 2020

When a character's pose changes, its center of mass(COM) also changes. The change of COM has distinctive patterns corresponding to various motion types like walking, running or sitting. Thus the motion type can be predicted by using COM movement. We propose a motion generator that uses character's center of mass information. This generator can generate various motions without annotated action type labels. Thus dataset for training and running can be generated full-automatically. Our neural network model takes the motion history of the character and its center of mass information as inputs and generates a full-body pose for the current frame, and is trained using simple Convolutional Neural Network(CNN) that performs 1D convolution to deal with time-series motion data.

• Journal of the Korea Computer Graphics Society
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• v.27 no.3
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• pp.13-23
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• 2021

In this paper, we proposed a framework that generates the trajectory of a single rigid body based on its COM configuration and contact pose. Because we use a smaller input dimension than when we use a full body state, we can improve the learning time for reinforcement learning. Even with a 68% reduction in learning time (approximately two hours), the character trained by our network is more robust to external perturbations tolerating an external force of 1500 N which is about 7.5 times larger than the maximum magnitude from a previous approach. For this framework, we use centroidal dynamics to calculate the next configuration of the COM, and use reinforcement learning for obtaining a policy that gives us parameters for controlling the contact positions and forces.

• Journal of Intelligence and Information Systems
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• v.11 no.2
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• pp.59-79
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• 2005

Export containers in a container terminal are usually classified into a few weight groups and those belonging to the same group are placed together on a same stack. The reason for this stacking by weight groups is that it becomes easy to have the heavier containers be loaded onto a ship before the lighter ones, which is important for the balancing of the ship. However, since the weight information available at the time of container arrival is only an estimate, those belonging to different weight groups are often stored together on a same stack. This becomes the cause of extra moves, or rehandlings, of containers at the time of loading to fetch out the heavier containers placed under the lighter ones. In this paper, we use machine learning techniques to derive a classifier that can classify the containers into the weight groups with improved accuracy. We also show that a more useful classifier can be derived by applying a cost-sensitive learning technique, for which we introduce a scheme of searching for a good cost matrix. Simulation experiments have shown that our proposed method can reduce about 5$\sim$7% of rehandlings when compared to the traditional weight grouping method.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.4
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• pp.627-654
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• 2016

Despite the significance of the measurement strand in elementary mathematics education, it is not easy to teach it meaningfully. This study analyzed instructional methods related to capacity and weight in a series of mathematics textbooks of Korea, Japan, Singapore, and the US. The overall analysis was conducted in the following two aspects: (a) what and when to teach main learning content, and (b) how to teach the learning content tailored to the instructional components specific to the topics of measurement (i.e., the necessity of measurement unit, the meanings of measurement terms, appropriate choice of units, appropriate choice of measurement tools, and the necessity of calculation). The results of this study showed overall similarities in using real-life contexts to teach major topics on capacity and weight as well as emphasizing the relations among measurement units. However, noticeable differences were also analyzed in dealing with the meanings of measurement terms, appropriate choice of units, and appropriate choice of measurement tools. Based on these results, this study provides textbook writers with implications on what to further consider in dealing with capacity and weight.

• Journal of The Korean Association For Science Education
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• v.34 no.3
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• pp.295-301
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• 2014

The purpose of this study is to investigate the difficulties of teachers and students on the unit about 'measuring weight.' In this research, we have acquired data about teachers through survey, interview, and self-reflection journals, at the same time we have collected information on the students through survey, assessment test, and interview. We have extracted the difficulties from analysis with constant comparison method. In addition, we have analysed the curriculum of science and mathematics to know the leaning sequence. The analysis had been checked up by experts in science education. The result of the study is as follows: The difficulties of teachers are from the lack of teachers' descriptive knowledge, disorder of conceptual hierarchy in the curriculum, poor experimental instruments, and low psychomotor skill of students. The difficulties of students are from common misconceptions, opaque concepts, lack of manipulation skill, insufficiency of mathematical ability, difficulty of application of principles to the real situation, and lack of problem-solving ability. In addition, teachers have recognized that students face more difficulties in experiment class, while students think that they face more difficulties in conceptual understanding class.

• Journal of Educational Research in Mathematics
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• v.26 no.3
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• pp.421-442
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• 2016

This study analyzed characteristics which emerged while 38 secondary school teachers observed a video clip about a centroid of triangles instruction. The aim of this study based on the analysis was to deduce implications in terms of the various means which would enhance teachers' knowledge in teaching mathematics and assist in designing mathematics education programs for teachers and professional development initiatives. To achieve this goal, this research firstly reviewed previous studies relevant to the 'Knowledge Quartet' as a framework of analyzing teachers' knowledge in mathematics instructions. Secondly, this study probed the observation results from the teachers in the light of the KQ. Therefore, some issues in the teacher education program for teaching mathematics were thirdly identified in the categories of 'Foundation', 'Transformation', 'Connection', and 'Contingency' based on the analysis. This research inspires the elaboration of what features have with regard to effective teachers' knowledge in teaching mathematics through the analyzing process and additionally the elucidation of essential matters related to mathematics education on the basis of the analyzed results.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.4
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• pp.551-559
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• 2017

In this paper, a real-time training method to improve the performance of bearing fault diagnosis. The traditional bearing fault diagnosis cannot classify a condition which is not trained by the classifier. The proposed 4-step method trains and recognizes new condition in real-time, thereby it can classify the condition accurately. In the first step, we calculate the maximum distance value for each class by calculating a Euclidean distance between a feature vector of each class and a centroid of the corresponding class in the training information. In the second step, we calculate a Euclidean distance between a feature vector of new acquired data and a centroid of each class, and then compare with the allowed maximum distance of each class. In the third step, if the distance between a feature vector of new acquired data and a centroid of each class is larger than the allowed maximum distance of each class, we define that it is data of new condition and increase count of new condition. In the last step, if the count of new condition is over 10, newly acquired 10 data are assigned as a new class and then conduct re-training the classifier. To verify the performance of the proposed method, bearing fault data from a rotating machine was utilized.