• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.358-360
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• 2002

한국전력은 당진화력발전소로부터 신안성 변전소까지의 세계 최초로 수직배열 2회선의 765kV 송전선로를 건설하여 2002년 4월부터 1회선을 765kV로 가압하고 1회선은 345kV로 상업운전을 시작하였으며 2003년 이후 2회선을 모두 765kV 전압으로 가압 예정이다. 이러한 765kV 송전선로는 계통운영 측면에서 2회선 동시 휴전이 어려워 1회선 휴전 작업 및 향후 활선작업이 요구되는 중요선로이다. 765kV 1회선 휴전작업을 위해서는 765kV로 가압된 선로로부터 휴전선로의 작업자에게 발생될 수 있는 전기적 유도량에 대해 사전 검토하여 안전성을 확보하는 것이 필수적이다. 한국전력공사와 전력연구원은 1회선 휴전작업에 대한 안정성 검토를 위해 고창 실증시험선로를 이용하여 전기적 유도현상에 대한 시험을 실시하였다. 이 논문에서는 실증시험 선로를 모델로한 정전유도의 계산 결과와 실측치를 각각 비교, 검토하였다.

• Spatial Information Research
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• v.12 no.2
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• pp.137-149
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• 2004

For 3D modelling artificial objects with computers, we have to draw frames and paint the facet images on each side. In this paper, a geographic modelling system building automatically 3D geographic spaces using GIS data and real images of buildings is proposed. First, the 3D model of terrain is constructed by using TIN and DEM algorithms. The images of buildings are acquired with a camera and its position is estimated using vertical lines of the image and the GIS data. The height of the building is computed with the image and the position of the camera, which used for making up the frames of buildings. The 3D model of the building is obtained by detecting the facet iamges of the building and texture mapping them on the 3D frame. The proposed geographical modeling system is applied to real area and shows its effectiveness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2C
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• pp.71-79
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• 2009

This study is to develope the resilient modulus prediction model, which is the function of mean effective principal stress and axial strain, for three types of railroad trackbed materials such as crushed stone, weathered granite soil, and crushed-rock soil mixture. The model consists of the maximum Young's modulus and nonlinear values for higher strain, analogous to dynamic shear modulus. The maximum value is modeled by model parameters, $A_E$ and the power of mean effective principal stress, $n_E$. The nonlinear portion is represented by modified hyperbolic model, with the model parameters of reference strain, ${\varepsilon}_r$ and curvature coefficient, a. To assess the performance of the prediction models proposed herein, the elastic response of a test trackbed near PyeongTaek, Korea, was evaluated using a 3-D elastic multilayer computer program (GEOTRACK). The results were compared with measured elastic vertical displacement during the passages of freight and passenger trains at two locations, whose sub-ballasts were crushed stone and weathered granite soil, respectively. The calculated vertical displacements of the sub-ballasts are within the order of 0.6mm, and agree well with measured values. The prediction models are thus concluded to work properly in the preliminary investigation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.191-198
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• 2007

The electromagnetic coupling between transmission lines in PCB design can degrade the performance of equipment operations. The coupling phenomenon is caused by electromagnetic fields generated by the currents on the transmission lines and the risers. In this paper, an improved method of crosstalk analysis for bent coupled lines on a PCB is proposed and investigated. In the previous cascading method combined with circuit-concept approach, bent coupled lines are devided into sections and each section is represented by ABCD matrix and then they are cascaded. In the proposed method, the crosstalk of bent coupled lines is calculated by the modified circuit-concept approach, where the coupled region is not restricted to the region projected by a generator line on a receptor line but is the total length of receptor line in calculating the forcing terms. Finally, the accuracy of the proposed approach is verified by comparing the calculated results with the measured ones for several bent coupled-line examples.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.545-552
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• 2018

Grounding line is used as evidence of the mass balance showing the vulnerability of Antarctic glaciers and ice shelves. In this research, we utilized a high resolution digital elevation model of glacier surface derived by recently launched satellites to estimate the position of grounding line of Campbell Glacier in East Antarctica. TanDEM-X and TerraSAR-X data in single-pass interferometry mode were acquired on June 21, 2013 and September 10, 2016 and CryoSat-2 radar altimeter data were acquired within 15 days from the acquisition date of TanDEM-X. The datasets were combined to generate a high resolution digital elevation model which was used to estimate the grounding line position. During the 3 years of observation, there weren't any significant changes in grounding line position. Since the average density of ice used in estimating grounding line is not accurately known, the variations of the grounding line was analyzed with respect to the density of ice. There was a spatial difference from the grounding line estimated by DDInSAR whereas the estimated grounding line using the characteristics of the surface of the optical satellite images agreed well when the ice column density was about $880kg/m^3$. Although the reliability of the results depends on the vertical accuracy of the bathymetry in this study, the hydrostatic ice thickness has greater influence on the grounding line estimation.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.29-46
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• 2014

For circular rigid footings with a rough base on sand, combined vertical - horizontal loading capacity was studied by three-dimensional numerical modelling. A numerical model was implemented to simulate the swipe loading and the probe loading methods and an interpretation procedure was devised in order to eliminate the numerical error from the restricted mesh density. Using the Mohr-Coulomb plasticity model, the effect of friction angle was studied under the associated flow-rule condition. The swipe loading method, which is efficient in that the interaction diagram can be drawn with smaller number of analyses, was confirmed to give similar results with the probe loading method, which follows closely the load-paths applied to real structures. For circular footings with a rough base, the interaction diagram for combined vertical (V) - horizontal (H) loading and the inclination factor were barely affected by the friction angle. It was found that the inclination factors for strip and rectangular footings are applicable to circular footings. For high H/V ratios, the results by numerical modelling of this study were smaller than the results of previous studies. Discussions are made on the factors affecting the numerical results and the areas for further researches.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.305-311
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• 2020

This study presents a probabilistic time series forecast of ship structural response using Bayesian inference combined with Volterra linear model. The structural response of a ship exposed to irregular wave excitation was represented by a linear Volterra model and unknown uncertainties were taken care by probability distribution of time series. To achieve the goal, Volterra series of first order was expanded to a linear combination of Laguerre functions and the probability distribution of Laguerre coefficients is estimated using the prepared data by treating Laguerre coefficients as random variables. In order to check the validity of the proposed methodology, it was applied to a linear oscillator model containing damping uncertainties, and also applied to model test data obtained by segmented hull model of 400,000 DWT VLOC as a practical problem.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.299-309
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• 2006

Railway noise and vibration has been recognized as major problems with the speed-up of rolling stock. As a kind of solution to these problems, the decrease of stiffness of track pad have been tried. However, in this case, overturning of rail due to lateral force should be considered because it can have effect on the safety of running train. Therefore, above two things - decrease of stiffness of track pad and overturning of rail due to lateral force - should be considered simultaneously for the appropriate determination of spring coefficient of track pad. With this viewpoint, minimum spring coefficient of track pad is estimated through the comparison between the theoretical relationship about the overturning of rail and 3-dimensional FE analysis result. Two kinds of Lateral force and wheel load are used as input loads. Extracted values from the conventional estimation formula and the Shinkansen design loads are used. It is found that the overturning of rail changes corresponding to the change of the stiffness of track pad and the ratio of lateral force to wheel load. Moreover, it is found that the analysis model can have influence on the results. Through these procedure, minimum spring coefficient of track pad is estimated.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.385-388
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• 2004

본 논문에서는 천해 해양환경에서 이동 음원과 수직선배열을 이용한 실 해상 실험 자료를 이용하여 지음향 역산 및 정합장처리를 수행하였다. 협대역 신호를 이용하여 음원의 이동에 따른 전달손실을 계산하였고, 이를 음파전달모델을 이용한 결과와 비교하는 방식으로 역산의 목적함수를 구성함으로써 해저면 지음향 인자들의 평균적인 값을 역산할 수 있었다. 역산 결과로 얻은 지음향 인자들을 사용하여 정합장처리를 통해 음원의 이동경로를 추적함으로써 역산 결과의 타당성을 검증하였고, 이를 기존 지질 자료를 이용한 정합장처리 결과와 비교하였다.

• Journal of the KSME
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• v.25 no.5
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• pp.394-399
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• 1985

금성통신에서 특정연구 사업으로 추진해 온 독자모델인 GSF-480를 중심으로 일반적인 FD D의 특성과 메카니즘(mechanism)에 대하여 기술하고자 한다. 현재 FDD의 주류를 이루고 있는 것이 5v1/4인치 양면 FDD이지만 소형화 대용량화에 의하여 점차 새로운 제품 즉 3.5인치, 3인치 FDD, 5v1/4인치 1M, 1.6M 버전(version)등이 개발되었다. 뿐만 아니라 트랙밀도를 높이는 외 에도 선밀도를 증가시키는 수직기록 방식도 개발될 전망이다. 그러나 대용량화가 되기 위하여 서는 FDD 상호간의 호환의 문제를 어떻게 하든 줄여야 할 것이다. 이를 위해서는 전술한 바와 같이 악세스 메카니즘의 정밀도 및 클램프시의 오차등 오프트랙 요인이 되는 것을 잘 고려하여야 한다. 국내에서는 기술도입 또는 자체개발로 FDD를 생산하고 있으며 금성통신은 83년 정부의 특정 연구사업으로 FDD를 개발 생산하고 있다. 앞으로 소형컴퓨터의 시장이 확대되고 수출이 늘어나게 되면 FDD의 시장도 확대될 것으로 전망되며 따라서 제품개발도 더욱 활발해질 것으로 기대된다.