• Wind and Structures
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• v.7 no.4
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• pp.281-291
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• 2004

The flutter characteristics of long span bridges are discussed from the point of the unsteady pressure distribution on bridge deck surface during heaving/torsional vibration related to the aerodynamic derivatives. In particular, it is explained that the coupling terms, which consist of $A_1^*$ and $H_3^*$, play a substantial role on the coupled flutter, in comparison with the flutter characteristics of various structural sections. Also the effect of the torsional/heaving frequency ratio of bridge structures on the flutter instability is discussed from the point of the coupling effect between heaving and torsional vibrations.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.120-123
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• 1993

This paper presents the developing a new algorithm for detecting the Back fed Earth Fault in three wire-unigrounded distribution system by zero sequence admittance. So called "Backfed Earth Fault" of the electric power distribution line refers to a class of earth faults that the load-side line only is grounded, following after the distribution line broken into two parts, the source-side and the load-side. Because its mechanism differs from that of other earth faults, it is therefore, required to examine. This paper deals with the detailed software of the digital protective relay for Backfed earth fault. In order to prove that the proposed schemes is good, we performed off-line simulation using data from EMTP and ETSA(Electrcity Trust Of South Austrilia). It is shown that the suggested algorithm is never mal operated.

• Journal of the Korean earth science society
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• v.37 no.5
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• pp.271-276
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• 2016

We present our estimate of pole shift caused by the recent 31 largest earthquakes of magnitude over 8.0. After reviewing theory of perturbation in the Earth's rotation, each co-seismic as well as post-seismic pole shifts by the earthquakes are acquired and illustrated. A total co-seismic excitation due to these earthquakes is ($x_1$, $x_2$)=(-3.35, 5.89) milliarcsec, which increased about twice the initial estimation when the post-seismic deformation is considered. The single largest co-seismic excitation by 2011 Japan earthquake was ($x_1$, $x_2$)=(-2.06, 2.36) milliarcsec, which corresponds to 9.7 cm pole shift on the surface of the Earth.

• Korean Journal of Child Studies
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• v.24 no.6
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• pp.95-115
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• 2003

This research examined he effects on preschool children's recognition of and attitude towards earth's nature of an early childhood environmental education program using children's literature. The subjects were 36 four-to six-year old children. The education program lasted for 8 weeks. Children were interviewed and surveyed about earth's nature, and the meanings of children's writings about nature were analyzed. The children who participated in this research showed a positive recognition of and attitudes towards the nature of the earth. Participants became keen observers of the world around them, examined the concept of change in nature, acquired knowledge about the earth through firsthand experiences, and developed caring attitudes for the natural world of the earth.

• Journal of the Korean earth science society
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• v.38 no.6
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• pp.427-441
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• 2017

Theory of Earth's free oscillation is revisited. Firstly, we summarized the underlying formulations, such as the equation of motion and its conversion into numerically integrable form and then explained computational procedures including the treatment of inner core-outer core boundary and core-mantle boundary, while the latter information has not been explicitly given in most publications. Secondly, we re-calculated the periods of Earth's free oscillation modes (period >200 s) for PREM model. In doing so we acquired the values of modes missing in Dziewonski and Anderson (1981). As a case observation, one seismogram after 2011 Tohoku earthquake recorded at Daejeon, Korea (KIGAM seismic station) was briefly analyzed to identify free oscillation mode excitations on its spectra. The material in this article will be most clear guide for those on calculating the Earth's free oscillation mode.

• International journal of advanced smart convergence
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• v.9 no.3
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• pp.97-104
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• 2020

In this paper, we propose a method to derive the kernel function directly from the measured apparent earth resistivity. At this time, the kernel function is obtained through the process of solving a nonlinear system. Nonlinear systems with many variables are difficult to solve. This paper also introduces a method for converting nonlinear derived systems to linear systems. The kernel function is a function of the depth and resistance of the Earth's layer. Being able to derive an accurate kernel function means that we can estimate the earth parameters i.e. layer depth and resistivity. We also use various Earth models as simulation examples to validate the proposed method.

• Journal of the Korean earth science society
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• v.25 no.1
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• pp.48-51
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• 2004

The light element candidates such as S, O, Si, and K are discussed for the reasonable compositions in the earth's core since the available data show density difference from pure iron core. These candidates are favored by the some evidences such as depletion in the crust and mantle, and lower eutectic temperature of Fe-FeS melt for sulfur. FeO phase for oxygen, lighter mass than sulfur and solubility in metallic phases for silicon, and partitioning in Fe-FeS melt for potassium. However, other problems such as short experimental data, initial compositions of these elements, and oxidation state during the formation of the earth should be solved simultaneously to confirm these light elements.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.4
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• pp.186-191
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• 2013

Earth equipments are essential to protect ITS facilities from abnormal situation. In this research, an estimation algorithm of earth parameters and equivalent resistivity is introduced. Traditional estimation methods can be divided into graphic method and numerical method. The result of graphic method is varied by the ability of expert or repeated calculation and it is hard to estimate the parameters precisely. The numerical method requires special techniques such as optimizing theory, and numerous calculations, whose results can be varied with initial values. The proposed algorithm is based on the relationship between apparent resistances and earth parameters and approximates the nonlinear characteristics of earth using ANN(artificial neural networks). The effectiveness of proposed method is verified in case studies.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.143-152
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• 2010

These days, we can't confirm cadastre information about stereoscopic digital map that was consist of 2 dimensions and more difficult to understand of detailed parcel boundary, area, land using for 3 dimensions. An each local government providing three-dimensional that are connected to an aerial photograph with cadastre maps. Satisfaction is high for citizens but, this service additional cost for purchase of an aerial photograph order to provide of it. So far, in various ways are under study about three dimensions using Google Earth which is possible to provides 3 dimensional information by real time for individual parcel situation. The purpose of this study was analyzed an accuracy of overlapping between cadstre maps and an image on Google Earth Web in the each different coordinates system. Also, this paper could be provided for use possibility of 3 dimensions information service with an indicator of using or a guideline of direction for local government which provide 3 dimensions information oneday.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.411-418
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• 2001

The last 30 years have been significant worldwide growth in the use of EPS as a lightweight fill material. This paper analyzes the compressible inclusion function of EPS which can results in reduction of static earth pressure by accomodating the movement of retained soil. A series of model tests was conducted to evaluate the reduction of static earth pressure using EPS inclusion and determine the optimum stiffness of EPS, Also, field test was conducted to evaluate the reduction of static earth pressure using EPS inclusion. Based on field test it is found that the magnitude of static earth pressure was reduced about 20% compared with theoretical active earth pressure.