• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1689-1694
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• 2009

In a previous paper, the characteristics of ECC (earth continuity conductor) have been analysed for reducing the level of induced sheath voltage considering the dimension and position of ECC, the spacing between ECC and three phase cables, and the use of two ECC conductors at the single point boned section of underground power cable system. From these results, the study conditions for optimal installation has been selected such as installation section, conductor size and etc. In this paper, 5 cases which are set by possible installation conditions are tested based on previous research results. Finally, the optimal installation method of ECC is selected on underground power cable systems.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.51.1-51.1
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• 2018

Based on the DOAO/eShels observations, we have derived radial velocity curves of the three Algol-type spectroscopic binary systems : Algol, ${\beta}$ Aur, and ${\varepsilon}$ Per. The radial velocity amplitudes of the primary and the secondary (K1 and K2) were consistent within a few % of the values from the previous studies. Mass ratios between the two stars that constitutes each system ranges ~1 to ~10. In addition to the orbital elements derived, we discuss about the spectroscopic ability of the DOAO/eShels instrument.

• Journal of the Korean earth science society
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• v.40 no.5
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• pp.476-486
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• 2019

This study examines the controlling role of synoptic disturbances on $PM_{10}$ spring variability in the Korean Peninsula by using empirical orthogonal function (EOF) and back trajectory analyses. Three leading EOF modes are identified, and a lead-lag analysis suggests that $PM_{10}$ variabilities be closely related to the synoptic weather systems. The first EOF shows the spatially homogeneous distribution of $PM_{10}$, which is influenced by travelling anticyclonic disturbance with negative precipitation and descending motion. The second and third modes exhibit the dipole structures of $PM_{10}$, being associated with propagating cyclones. Furthermore, the back-trajectory analysis suggests that the transport of pollutants by anomalous winds associated with synoptic disturbances also contribute to the altered $PM_{10}$ concentration. Hence, a substantial synoptic control should be considered in order to fully understand the $PM_{10}$ spatiotemporal variability.

• Journal of Information Processing Systems
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• v.20 no.1
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• pp.131-147
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• 2024

A routing strategy based on traffic prediction and dynamic cache allocation for satellite nodes is proposed to address the issues of high propagation delay and overall delay of inter-satellite and satellite-to-ground links in low Earth orbit (LEO) satellite systems. The spatial and temporal correlations of satellite network traffic were analyzed, and the relevant traffic through the target satellite was extracted as raw input for traffic prediction. An improved gradient boosting regression tree algorithm was used for traffic prediction. Based on the traffic prediction results, a dynamic cache allocation routing strategy is proposed. The satellite nodes periodically monitor the traffic load on inter-satellite links (ISLs) and dynamically allocate cache resources for each ISL with neighboring nodes. Simulation results demonstrate that the proposed routing strategy effectively reduces packet loss rate and average end-to-end delay and improves the distribution of services across the entire network.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1060-1065
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• 2005

An Independent Administrative Corporation Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is developing light-and-small Autonomous Underwater Vehicles (AUV)$^{1)}$, named 'MR-X1' (Marine Robot Experimental 1), which can cruise, investigate and observe by itself without human's help. In this paper, we consider the motion control problem of 'MR-X1' and derive a controller. Since the dynamic property of 'MR-X1' is changed by the influence of the speed, the mathematical model of 'MR-X1' becomes the nonlinear model. In order to design a controller for 'MR-X1', we generally apply nonlinear control theories or linear control theories with some constant speed situation. If we design a controller by applying Linear Quadratic (LQ) optimal control theory, the obtained controller only compensates t e optimality at the designed speed situation, and does not compensate the stability at another speed situations. This paper proposes a controller design method using Linear Matrix Inequalities (LMIs)$^{2),3),4)}$, which can adapt the speed variation of 'MR-X1'. And examples of numerical analysis using our designed controller are shown.

• KIEAE Journal
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• v.2 no.4
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• pp.41-47
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• 2002

East Asian explain the changes of substance happened on earth and those of human life with the conceptual frame of "Gi-ki"(地氣; earth vital energy) and organize them by the system of "Feng-shui(風水) theory. The core of Feng-shui theory is reading the expression of the nature and feeling the Gi-ki from the expression. One of the properties of the earth is that the earth has a magnetic field associated with it- the Geomagnetic field. The geomagnetic field is produced by a combination of the effects of electric currents in the earth's liquid core, the magnetization of crustal rocks, external electric current systems that surround the earth and currents induced in the outer layers of the earth by magnetic field variations. The sameness of logic between Feng-shui and geopathic zones is that both are concerned with the discrimination of site and the energy of places, in other words both disciplines are concerned with how the environment can influence people. In this context the operation of Gj-ki can be related with the effect caused by geomagnetic field on site. In this study Jongmyo(宗廟), one of the representative traditional architecture in Korea is selected because the site selection and building layout follows Feng-shui faithfully according to Taejo silok (太祖實錄, Annals of King Taejo). Observing the landforms surrounding Jongmyo, Jongmyo is apparently located in auspicious places named Gumge Poranhyoeng(金鷄抱卵形, a Feng-shui landscape of golden hen sitting on eggs). The geomagnetic investigation of Jongmyo shows that the geomagnetic values of Toekan(the space near Hyeol) are relatively high and uniform and those of Sangweoldae and Haweoldae are decreased in accordance with the distance. The result shows that there is possibility that Feng-shui has scientific basis related with geomagnetic field. Feng-shui theory can suggest a direction for designing the sustainable building for living with nature.

• Journal of the Korean earth science society
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• v.29 no.7
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• pp.602-616
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• 2008

The purpose of this study is to investigate the influence of global science literacy-oriented instruction on students' views of the nature of science. The participants were 65 male students in 8th grade, and they were taught for five weeks about the Unit of "Earth and Star" that was designed based on global science literacy. Survey was conducted to determine the students' views of the nature of science before and after the instruction. Results revealed that it was hard to change students' views of the nature of science during the short period of time; however, in the sociological aspect, the students acquired relatively more improved students' views of the nature of science than the other aspects including philosophical, psychological, and historical aspects.

• Korean Journal of Remote Sensing
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• v.37 no.1
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• pp.161-167
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• 2021

This paper presents the method to quantitatively evaluate the uncertainty of the semi-empirical Bidirectional Reflectance Distribution Function (BRDF) model for Himawari-8/AHI. The uncertainty of BRDF modeling was affected by various issues such as assumption of model and number of observations, thus, it is difficult that evaluating the performance of BRDF modeling using simple uncertainty equations. Therefore, in this paper, Monte-Carlo method, which is most dependable method to analyze dynamic complex systems through iterative simulation, was used. The 1,000 input datasets for analyzing the uncertainty of BRDF modeling were generated using the Second Simulation of a Satellite Signal in the Solar Spectrum (6S) Radiative Transfer Model (RTM) simulation with MODerate Resolution Imaging Spectroradiometer (MODIS) BRDF product. Then, we randomly selected data according to the number of observations from 4 to 35 in the input dataset and performed BRDF modeling using them. Finally, the uncertainty was calculated by comparing reproduced surface reflectance through the BRDF model and simulated surface reflectance using 6S RTM and expressed as bias and root-mean-square-error (RMSE). The bias was negative for all observations and channels, but was very small within 0.01. RMSE showed a tendency to decrease as the number of observations increased, and showed a stable value within 0.05 in all channels. In addition, our results show that when the viewing zenith angle is 40° or more, the RMSE tends to increase slightly. This information can be utilized in the uncertainty analysis of subsequently retrieved geophysical variables.

• Journal of the Korean Geotechnical Society
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• v.24 no.3
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• pp.25-34
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• 2008

A finite element analysis was performed for new earth retention system with prestressed wales. A 3D finite element model was adopted in this study to investigate the behavior of the earth retention system with prestressed wales. A procedure of the 3D finite element modeling of this earth retention system was presented. The procedure included the modeling of soil, wall, strut, and members of prestressed wale system which consists of wale, support leg, and steel wires, and the interface modeling of soil-wall and wall-wale. The numerical predictions of lateral wall deflection, and axial load on the members of prestressed wale systems and struts were evaluated in comparison with the measurements obtained from field instruments. A sensitivity analysis was performed using the proposed 3D finite element model to investigate the behavior of new earth retention system on a wide range of prestress load conditions of steel wires. The lateral deflection of the wall and wale, the bending moment of the wale, and the lateral earth pressure distribution on the wall were computed. Implications of the results from this study were discussed.

• Publications of The Korean Astronomical Society
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• v.38 no.3
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• pp.125-145
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• 2023

This study investigates the integration of astronomy-related topics in the Korean national science curricula spanning from 1945 to 2023. We analyze the placement and extent of astronomy content across different school levels. Astronomy contents in the science curricula have changed in response to social needs (e.g., practical knowledge required for agriculture and fishery) and advancement in astronomical research (e.g., the discovery of exoplanets and the suggestion of new cosmological parameters). Contents addressing the motions of celestial objects and stellar physical properties have remained relatively consistent. In the latest 2022 revised national curriculum, scheduled for implementation in 2024, several elements, such as coordinate systems, have been removed, while the inquiry activities using digital tools are emphasized. The incorporation of the cosmic perspectives in the national curriculum, as well as astronomy education within the context of education for sustainable development, remains limited even in the most recent curriculum. For future life revisions, the active participation of researchers is needed to reflect the latest astronomical research progress and scientific characteristics in the field of astronomy.