• 한국초전도학회:학술대회논문집
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• v.10
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• pp.216-220
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• 2000

AC Superconducting Generators (ACSG) are featured by 3D magnetic flux distribution, which decreases in the direction of axis. For this reason, when ACSG is optimal designed, 3D magnetic field analysis is required. This paper proposes 2D Finite Element Analysis (FEA) results normalized by 3D FEA according to the position of armature coil and the ratio of field coil width to axial length in order to reduce the analysis time. By using the proposed data, the reasonable 3D FEA results of ACSG can be only predicted by 2D FEA results. The validity of the 3D FEA results is verified by comparison with the experimental results of 30kVA superconducting synchronous generator.

• Progress in Superconductivity and Cryogenics
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• v.15 no.1
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• pp.25-28
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• 2013

We report processing technique in the MO image measurement system. Calibration procedure is not only considered to perpendicular field but also in-plane field. Current density and field profiles are obtained by Biot-savart law and inversion method. We show example of $(Gd,Y)_1Ba_2Cu_3O_{7-{\delta}}-BaZrO_3$ film that have tilted nano rod pinning centers about $13^{\circ}$ from the c-axis.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.66.3-66.3
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• 2016

We report preliminary results from our analyses on the star-forming galaxies in the Herschel/SPIRE survey data over the AKARI/NEP-Wide Field. In this work, we utilize a combination of the SPIRE point source catalogue containing ~ 4,800 sources distributed over the wide (5.6 sq. deg) field and the spectroscopic redshift (zSPEC) data for 1790 selected targets obtained by MMT/Hectospec and WIYN/Hydra. Our analyses take advantages of multi-wavelengths photometric data (28 bands at most) covering from u* to $500{\mu}m$ band as well as continuous MIR wavelengths sampling by AKARI and WISE (4 to $25{\mu}m$). Various physical properties such as total infrared luminosity (LTIR), star formation rate (SFR), and luminosity functions (LFs) will be presented.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.169-180
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• 2019

In this study, a batch least square estimator that utilizes optical observation data is developed and utilized to determine geostationary orbits (GEO). Through numerical simulations, the effects of error sources, such as clock errors, measurement noise, and the a priori state error, are analyzed. The actual optical tracking data of a GEO satellite, the Communication, Ocean and Meteorological Satellite (COMS), provided by the optical wide-field patrol network (OWL-Net) is used with the developed batch filter for orbit determination. The accuracy of the determined orbit is evaluated by comparison with two-line elements (TLE) and confirmed as proper for the continuous monitoring of GEO objects. Also, the measurement residuals are converged to several arcseconds, corresponding to the OWL-Net performance. Based on these analyses, it is verified that the independent operation of electro-optic space surveillance systems is possible, and the ephemerides of space objects can be obtained.

• Journal of Environmental Science International
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• v.31 no.9
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• pp.757-766
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• 2022

This study is to examine how well the hydrologic model reproduces the dam collapse. To do this, A hydrologic model FLO-2D is being operated to reproduce dam collapse with rainfall data and surface data in a small dam. In order to examine the performance of the model, the simulation was compared and reviewed with the data collected through the field survey. The results show that it takes about 2 hours to reach 1 km downstream. Inundation areas are about 188,640 m2 by the simulation and the difference from the field investigation is about 6.1%. Ten representative points were selected from the areas where the simulation and the field survey did not match. The discrepancy is less than about 0.08 m and does not appear to be significant. This study will present basic information on disaster preparedness operation and planning to minimize damage caused by sudden collapse of agricultural soil dams in the future.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.27-50
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• 2009

This paper describes an adaptive management approach for predicting, monitoring, and controlling ground movements associated with excavations in urban areas. Successful use of monitoring data to update performance predictions of supported excavations depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the optimization techniques used to minimize the difference between predictions and observed performance. This paper summarizes each of these factors and emphasizes their inter-dependence. Numerical considerations are described, including the initial stress and boundary conditions, the importance of reasonable representation of the construction process, and factors affecting the selection of the constitutive model. Monitoring data that can be used in conjunction with current numerical capabilities are discussed, including laser scanning and webcams for developing an accurate record of construction activities, and automated and remote instrumentations to measure movements. Self-updating numerical models that have been successfully used to compute anticipated ground movements, update predictions of field observations and to learn from field observations are summarized. Applications of these techniques from case studies are presented to illustrate the capabilities of this approach.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.231-241
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• 2019

Web Usage Mining (WUM) is one part of Web mining and also the application of data mining technique. Web mining technology is used to identify and analyze user's access patterns by using web server log data generated by web users when users access web site. So first of all, it is important that the data should be acquired in a reasonable way before applying data mining techniques to discover user access patterns from web log. The main task of data acquisition is to efficiently obtain users' detailed click behavior in the process of users' visiting Web site. This paper mainly focuses on data acquisition stage before the first stage of web usage mining data process with activities like data acquisition strategy and field extraction algorithm. Field extraction algorithm performs the process of separating fields from the single line of the log files, and they are also well used in practical application for a large amount of user data.

• 한국정보교육학회:학술대회논문집
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• 2021.08a
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• pp.393-400
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• 2021

Data science is a scientific discipline that defines problems while finding meaningful information from collected data to solve problems. Along with artificial intelligence technology, the field of data utilization is gradually expanding, and awareness of the importance of data science education is also increasing. Despite the rapid growth of the domestic data industry market, it has recently been predicted that the shortfall of data experts will reach 31.4% within the next 5 years according to an analysis of the current status of the data industry by the Korea Data Agency. In the field of elementary education, various studies have been conducted to introduce data science in order to improve students' computational thinking and creativity. This paper proposed the contents of data science lectures developed for the purpose of educating elementary school teachers, who are mostly non-majors in the computer field. The developed contents were applied to a group of elementary school teachers attending graduate school for artificial intelligence convergence education. Points for improvement were derived by identifying the contents that were difficult for learners to understand and analyzing the causes of difficulty.

• The Journal of Korea Robotics Society
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• v.13 no.3
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• pp.190-197
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• 2018

Geomagnetic field signals have potential for use in underwater navigation and geophysical surveys. To map underwater geomagnetic fields, we propose a method that exploits an autonomous surface vehicle. In our system, a magnetometer is rigidly attached to the vehicle and not towed by a cable, minimizing the system's size and complexity but requiring a dedicated calibration procedure due to magnetic distortion caused by the vehicle. Conventional 2D methods can be employed for the calibration by assuming the horizontal movement of the magnetometer, whereas the proposed 3D approach can correct for horizontal misalignment of the sensor. Our method does not require a supporting crane system to rotate the vehicle, and calibrates and maps simultaneously by exploiting data obtained from field operation. The proposed method has been verified experimentally in inland waters, generating a magnetic field map of the test area that is of much higher resolution than the public magnetic field data.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.1
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• pp.34-45
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• 2010

This paper describes the design, manufacturing process, testing, application, and assessment of capacity-ratings of the first all advanced composites bridge on a public highway system. In order to verify the bridge design prior to the field application, a sub-scale bridge superstructure was built and tested in the laboratory. The field load test results were compared with those of the finite element analysis for the verification of validity. To investigate its in-service performance, field load testing and visual inspections were conducted under an actual service environment. The paper includes the presentation and discussion for advanced composites bridge capacity rating based on the stress modification coefficients obtained from the test results. The test result indicates that the advanced composites bridge has no structural problems and is structurally performing well in-service as expected. Since these composite materials are new to bridge applications, reliable data is not available for their in-service performance. The results may provide a baseline data for future field advanced composites bridge capacity rating assessments and also serve as part of a long-term performance of advanced composites bridge.