• Journal of Information Processing Systems
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• v.14 no.3
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• pp.569-589
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• 2018

Cloud computing, also known as "country as you go", is used to turn any computer into a dematerialized architecture in which users can access different services. In addition to the daily evolution of stakeholders' number and beneficiaries, the imbalance between the virtual machines of data centers in a cloud environment impacts the performance as it decreases the hardware resources and the software's profitability. Our axis of research is the load balancing between a data center's virtual machines. It is used for reducing the degree of load imbalance between those machines in order to solve the problems caused by this technological evolution and ensure a greater quality of service. Our article focuses on two main phases: the pre-classification of tasks, according to the requested resources; and the classification of tasks into levels ('odd levels' or 'even levels') in ascending order based on the meta-heuristic "Bat-algorithm". The task allocation is based on levels provided by the bat-algorithm and through our mathematical functions, and we will divide our system into a number of virtual machines with nearly equal performance. Otherwise, we suggest different classes of virtual machines, but the condition is that each class should contain machines with similar characteristics compared to the existing binary search scheme.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.2
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• pp.19-37
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• 2021

It is essential that the evaluation of official development assistance (ODA) projects is conducted based on empirical research for the performance and improvement of the project. This study intended to quantitatively figure out the actual status and performance of ODA projects. The performance of the Rumpin Seed Source and Nursery Center project implemented by the KOICA was evaluated in items of relevance, efficiency, effectiveness, impact, sustainability, which are OECD Development Assistance Committee(DAC) evaluation criteria. From August 26, 2019 to August 29, 2019, a survey was conducted on 50 visitors and 54 stakeholders of the Rumpin Seed Source and Nursery Center. Through on-site survey, problems in the donation project and operation in Indonesia were identified and measures for improvement was grasped. As a result of the study, the value scored by OECD DAC evaluation criteria of the Rumpin Seed Source and Nursery Center project based on the Economic Development Cooperation Fund(EDCF) evaluation grade was evaluated as a very successful class in all items. The average score of the recognition question was 4.08 points for visitors and 4.08 points for stakeholders, and the average score for the satisfaction question was 4.37 points for visitors and 4.11 points for stakeholders, which were high overall in both groups. The main factor that affects the project awareness of the visitors was the fact that the Rumpin Seed Source and Nursery Center was created based on Korean technology, and it was confirmed that Indonesia's own items related to similar projects had a great influence on the project satisfaction. In the case of stakeholders, project support in Korea affected their recognition, and it was found that relevance, efficiency, effectiveness items had the greatest impact on the level of project satisfaction of stakeholders derived from the DAC individual evaluation results. Efforts are required to increase the main factors by reflecting the results of each item and to preserve and maintain the project. This study is significant in determining the performance of the ODA project based on empirical data, and it is believed that it can be used as basic data for supplementing and strengthening the project in the future.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.163-171
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• 2003

To evaluate the performance of the digital radiography(DR) system developed in our group, the modulation transfer function(MTF) was measured and compared with that of an analog X- ray detector, film/screen system. The DR system has an amorphous selenium(a-Se) layer vacuum-evaporated on a TFT flat panel detector. The speed class 400 film/screen (Fuji) system has been being used in the clinical field as analog X-ray detectors. Both the square wave and slit method were used to evaluate their MTF. The square method was applied to both film/screen and the DR system. The slit method, however, was applied to only DR system. The full-width half maximum resolution of film/screen was 357${\mu}{\textrm}{m}$(1.4 lp/mm at 50% spatial frequency), and the resolution of DR was limited to 200${\mu}{\textrm}{m}$(2.5 lp/mm at 30%). These results indicate the measured resolution limitations approximate to the pixel pitch, 139 ${\mu}{\textrm}{m}$ of TFT. The MTF of DR is higher than that of film/screen by the factor of 1.785. It is proved that our a-Se based DR system has potential usefulness in the clinical field.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.531-554
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• 2020

In order to provide explanations of the practice of the abductive inquiry-based outdoor geological fieldwork education, this study examined the characteristics of students' performance in geological fieldwork before and after the introduction of explicit learning of geologic knowledge and inquiry. To this end, a 21st-class program was developed in the order of pre-evaluation, initial fieldwork, explicit learning of geologic knowledge and inquiry, and post-evaluation and applied to nine middle school students. As research data, outdoor geological fieldwork class recording data and students' activity sheets were collected and analyzed qualitatively. As a result, during the initial fieldwork, students caught clues of low geological importance and used everyday experience and/or general scientific knowledge as a rule when asked to generate hypotheses about the origin of the clues. Also, students evaluated their hypotheses by the scientific accuracy of the rule or their own criterion. Meanwhile, during the final fieldwork, students frequently caught key clues in geologic perspectives and generated geological event hypotheses related to the clues by borrowing geologic knowledge as a rule. Furthermore, students scientifically evaluated their hypotheses based on the consistency of evidence and rules. Combining these results, the effects of learners' geological knowledge and inquiry (abduction) abilities as a path model were presented in order to help students carry out a proficient abductive inquiry in geological fieldwork.

• The Mathematical Education
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• v.63 no.3
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• pp.549-571
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• 2024

As digital·AI-based teaching and learning is emphasized, discussions on the educational use of generative AI are becoming more active. This study analyzed the mathematical performance of ChatGPT 4, Claude 3 Opus, and Gemini Advanced on solving examples and problems from five first-year high school math textbooks. As a result of examining the overall correct answer rate and characteristics of each skill for a total of 1,317 questions, ChatGPT 4 had the highest overall correct answer rate of 0.85, followed by Claude 3 Opus at 0.67, and Gemini Advanced at 0.42. By skills, all three models showed high correct answer rates in 'Find functions' and 'Prove', while relatively low correct answer rates in 'Explain' and 'Draw graphs'. In particular, in 'Count', ChatGPT 4 and Claude 3 Opus had a correct answer rate of 1.00, while Gemini Advanced was low at 0.56. Additionally, all models had difficulty in explaining using Venn diagrams and creating images. Based on the research results, teachers should identify the strengths and limitations of each AI model and use them appropriately in class. This study is significant in that it suggested the possibility of use in actual classes by analyzing the mathematical performance of generative AI. It also provided important implications for redefining the role of teachers in mathematics education in the era of artificial intelligence. Further research is needed to develop a cooperative educational model between generative AI and teachers and to study individualized learning plans using AI.

• Structural Engineering and Mechanics
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• v.62 no.1
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• pp.21-31
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• 2017

Engineered Cementitious Composite (ECC) is a special class of the new generation of high performance fiber reinforced cementitious composites (HPFRCC) featuring high ductility with relatively low fiber content. In this research, the mechanical performance of ECC beams will be investigated with respect to the effect of slag and aggregate size and amount, by employing nonlinear finite element method. The validity of the models was verified with the experimental results of the ECC beams under monotonic loading. Based on the numerical analysis method, nonlinear parametric study was then conducted to evaluate the influence of the ECC aggregate content (AC), ECC compressive strength ($f_{ECC}$), maximum aggregate size ($D_{max}$) and slag amount (${\phi}$) parameters on the flexural stress, deflection, load and strain of ECC beams. The simulation results indicated that when increase the slag and aggregate size and content no definite trend in flexural strength is observed and the ductility of ECC is negatively influenced by the increase of slag and aggregate size and content. Also, the ECC beams revealed enhancement in terms of flexural stress, strain, and midspan deflection when compared with the reference beam (microsilica MSC), where, the average improvement percentage of the specimens were 61.55%, 725%, and 879%, respectively. These results are quite similar to that of the experimental results, which provides that the finite element model is in accordance with the desirable flexural behaviour of the ECC beams. Furthermore, the proposed models can be used to predict the flexural behaviour of ECC beams with great accuracy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.369-378
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• 2012

In this study, direct-search based optimization methods are applied for blade shape optimization of wind turbines and the optimization performances of several methods including conventional genetic algorithm, micro genetic algorithm and pattern search method are compared to propose a more efficient method. For this purpose, the currently available version of HARP_Opt (Horizontal Axis Rotor Performance Optimizer) code is enhanced to rationally evaluate the annual energy production value according to control strategies and to optimize the blade shape using pattern search method as well as genetic algorithm. The enhanced HARP_Opt code is applied to obtain the optimal turbine blade shape for 1MW class wind turbines. The results from pattern search method are compared with the results from conventional genetic algorithm and also micro genetic algorithm and it is found that the pattern search method has a better performance in achieving higher annual energy production and consistent optimal shapes and the micro genetic algorithm is better for reducing the calculation time.

• Fire Science and Engineering
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• v.29 no.2
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• pp.13-19
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• 2015

Real scale fire tests was carried out for extinguishing performance evaluation of the wetting agent. The experiment was conducted in accordance with a Class A fire extinguishing test methods specified in the 'Type Approval of the Manual System Fire Extinguisher and Technical Standards of Test'. In addition, the subjects of this experiment were the wood flour and rice husk. Fire-fighting water, the three kinds of wetting agents used in the country and this study was used, was undertaken to determine a clear discrimination of the water and wetting agent. In the experimental results, it was confirmed that the internal temperature is maintained long time in the case of water. The internal temperature were rapidly lowered in the experiment of wetting agents. Therefore, the discrimination of extinguishing ability was confirmed by the temperature distribution in accordance with time. Based on the results of this experiment, this study is expected to be used as a underlying material on presenting a method of optimized performance evaluation of wetting extinguishing agent.

• Journal of Science Education
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• v.40 no.3
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• pp.203-218
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• 2016

The purpose of this study was to investigate the effects of reflective thinking-based laboratory report on learners' metacognition and inquiry skills. In a general physics experiment class consisting of 11 experiments, 20 college students used reflective thinking-based laboratory report, and then the changes of their metacognition and inquiry skills were compared with those of who used general laboratory report. The opinions of students used reflective thinking-based laboratory report were surveyed. The results showed that their metacognitions were increased more than those of comparison group that used common experiment report. Their inquiry skills also were increased as much as comparison group's. According to the survey results, they recognized that reflective thinking-based laboratory report helps to improve their performance, metacognitions, and inquiry skills.

• The korean journal of orthodontics
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• v.43 no.1
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• pp.42-52
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• 2013

The aim of this paper was to propose a new method of bimaxillary orthognathic surgery planning and model surgery based on the concept of 6 degrees of freedom (DOF). A 22-year-old man with Class III malocclusion was referred to our clinic with complaints of facial deformity and chewing difficulty. To correct a prognathic mandible, facial asymmetry, flat occlusal plane angle, labioversion of the maxillary central incisors, and concavity of the facial profile, bimaxillary orthognathic surgery was planned. After preoperative orthodontic treatment, surgical planning based on the concept of 6 DOF was performed on a surgical treatment objective drawing, and a Jeon's model surgery chart (JMSC) was prepared. Model surgery was performed with Jeon's orthognathic surgery simulator (JOSS) using the JMSC, and an interim wafer was fabricated. Le Fort I osteotomy, bilateral sagittal split ramus osteotomy, and malar augmentation were performed. The patient received lateral cephalometric and posteroanterior cephalometric analysis in postretention for 1 year. The follow-up results were determined to be satisfactory, and skeletal relapse did not occur after 1.5 years of surgery. When maxillary and mandibular models are considered as rigid bodies, and their state of motion is described in a quantitative manner based on 6 DOF, sharing of exact information on locational movement in 3-dimensional space is possible. The use of JMSC and JOSS will actualize accurate communication and performance of model surgery among clinicians based on objective measurements.