• 항공우주기술
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• 제13권2호
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• pp.99-107
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• 2014

다목적실용위성 2호/3호 위성자료를 이용하여 지상좌표를 결정하는 방법은 Physical Model과 RFM(Rational Function Model)의 두 가지 종류가 있다. 일반적으로 사용자에게 제공되는 모델은 RFM을 기반으로 한 RPCs(Rational Function Coefficients)이며, 이때 제공되는 RPCs는 지상좌표에서 영상좌표를 계산하는 계수이다. 사용자가 정사영상을 만들 경우에는 이 계수가 유용하나, 영상에서 임의의 영상기준점에 대응하는 지상좌표를 계산하거나, 위치정확도를 확인하기는 매우 어렵다. 본 논문은 다목적실용위성에서 제공되는 RPCs를 기반으로 Inverse RPCs를 해석하는 알고리즘과 해석된 Inverse RPCs를 기반으로 지상표고를 고려한 정밀 지상좌표 해석 알고리즘을 기술하고자 한다. 또한 Inverse RPCs의 해석된 정밀지상좌표 정확도와 Physical Model과의 차이를 계산하여 정확도를 평가하고자 한다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.155-160
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• 2005

To purpose of this research is to develop the numerical model for simulating performance of ground heat exchanger with high prediction accuracy. This paper describes the development of a numerical model that simulates the heat transfer between ground and circulation water in ground heat exchanger. Furthermore, we propose the estimating technique of soil properties, such as thermal conductivity, heat capacity and hydraulic conductivity, based on ground investigation. Comparison between experiment and numerical analysis based on the model developed above was conducted under the condition of the experiment in 2004. The result of analysis agreed well with the experimental result.

• Earthquakes and Structures
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• 제10권3호
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• pp.563-588
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• 2016

In this study, solution models are proposed to obtain code-compatible ground motion record sets which can be used for both uni-directional and bi-directional dynamic analyses. Besides scaled, unscaled ground motion record sets are obtained to show the utility and efficiency of the solution models. For scaled ground motion sets the proposed model is based on hybrid HS-Solver which integrates heuristic harmony search (HS) algorithm with the spreadsheet Solver add-in. For unscaled ground motion sets HS based solution model is proposed. Design spectra defined in Eurocode-8 for different soil types are selected as target spectra. The European Strong Motion Database is used to get ground motion record sets. Also, a sensitivity analysis is conducted to evaluate the effect of different HS solution parameters on the solution accuracy. Results show that the proposed solution models can be regarded as efficient ways to develop scaled and unscaled ground motion sets compatible with code-based design spectra.

• 한국터널지하공간학회 논문집
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• 제17권6호
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• pp.575-586
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• 2015

NATM터널의 콘크리트 라이닝에 작용하는 지반하중을 산정하는 방법으로 수치해석적 기법인 지반-라이닝 상호작용모델(Ground-Lining Interaction Model, GLI 모델)에 의한 지반하중 산정방법이 제안되었다. 그러나, 기존의 GLI 모델은 지반과 지보재 또는 콘크리트 라이닝 사이에 존재하는 계면(Interface)의 구조적 역할을 반영하지 못하였다. 이에 본 연구에서는 기존의 GLI 모델에 계면요소를 반영하여 보다 실제에 가까운 모델로 구현하였다. 그리고, 지반조건 및 토피별 지반하중을 수치해석을 통해 산정하고 기존의 GLI모델 지반하중 상관식을 수정하여 제안하였다. 연구결과, 기존 모델에 비해 계면요소 반영시 지반하중은 토피두께에 따라 IV등급 지반조건에서는 평균 88~106%, 풍화토 지반조건에서는 평균 47~57% 수준으로 감소하였다. 본 연구결과로 콘크리트 라이닝에 작용하는 지반하중을 실제에 가까운 모델로 산정할 수 있으며, 상관식을 이용하여 일관되고 경제적인 설계가 가능하게 될 것으로 예상된다.

• Structural Engineering and Mechanics
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• 제6권1호
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• pp.63-76
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• 1998

This paper presents dynamic responses of structures with sliding base which limits the translation of external loads from ground excitation. A discrete element model based on the discontinuous deformation analysis method is proposed to study this sliding boundary problem. The sliding base is simulated using sets of fictitious contact springs along the sliding interface. The set of contact spring is to translate friction force from ground to superstructure. Validity of the proposed model is examined by the closed-form solutions of an idealized mass-spring structural model subjected to harmonic ground excitation. This model is also applied to a problem of a three-story structural model subjected to the ground excitation of 1940 El Centro earthquake. Analyses of both sliding-base and fixed-base conditions are performed as comparisons. This study shows that using this model can simulate the dynamic response of a sliding structure with frictional cut-off quite accurately. Results reveal that lowering the frictional coefficient of the sliding joint will reduce the peak responses. The structure responses in little deformation, but it displaces at the end of excitation.

• 한국지진공학회논문집
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• 제27권5호
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• pp.221-230
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• 2023

This study proposes a methodology for assessing seismic liquefaction hazard by implementing high-resolution three-dimensional (3D) ground models with high-density/high-precision site investigation data acquired in an area of interest, which would be linked to geotechnical numerical analysis tools. It is possible to estimate the vulnerability of earthquake-induced geotechnical phenomena (ground motion amplification, liquefaction, landslide, etc.) and their triggering complex disasters across an area for urban development with several stages of high-density datasets. In this study, the spatial-ground models for city development were built with a 3D high-precision grid of 5 m × 5 m × 1 m by applying geostatistic methods. Finally, after comparing each prediction error, the geotechnical model from the Gaussian sequential simulation is selected to assess earthquake-induced geotechnical hazards. In particular, with seven independent input earthquake motions, liquefaction analysis with finite element analyses and hazard mappings with LPI and LSN are performed reliably based on the spatial geotechnical models in the study area. Furthermore, various phenomena and parameters, including settlement in the city planning area, are assessed in terms of geotechnical vulnerability also based on the high-resolution spatial-ground modeling. This case study on the high-precision 3D ground model-based zonations in the area of interest verifies the usefulness in assessing spatially earthquake-induced hazards and geotechnical vulnerability and their decision-making support.

• 한국지진공학회논문집
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• 제20권1호
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• pp.45-54
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• 2016

This study suggests a prediction model of ground motion spectral shape considering characteristics of earthquake records in Korea. Based on the Graizer and Kalkan's prediction procedure, a spectral shape model is defined as a continuous function of period in order to improve the complex problems of the conventional models. The approximate spectral shape function is then developed with parameters such as moment magnitude, fault distance, and average shear velocity of independent variables. This paper finally determines estimator coefficients of subfunctions which explain the corelation among the independent variables using the nonlinear optimization. As a result of generating the prediction model of ground motion spectral shape, the ground motion spectral shape well estimates the response spectrum of earthquake recordings in Korea.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.63-65
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• 2003

The purpose of the study is to produce the surface ground temperature diagnostically using surface EBM with the use of GRID model in Geographic Information Systems (GIS). Certain characteristics have been analyzed for local slope effect, coastal effect and influence of high orographic aspect on the surface ground temperature. We present discussions on the meteorological responsibility for their temperature. The derived surface ground temperatures can be provided for comparison with those from satellite-based observ ation.

• 한국전산유체공학회지
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• 제15권4호
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• pp.53-59
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• 2010

Preliminary design of a ground plate, a device installed close to the aircraft model for wind tunnel test to simulate the ground effect, was performed by a numerical simulation. A two-dimensional numerical study was performed initially to decide the optimal leading edge and flap configurations. Then, three-dimensional studies were conducted to decide the optimal flap deflection angle for pressure distribution reduction since the plate and the plate supporting system generate static pressure difference between the upper and lower flow regions. Three-dimensional simulation additionally studied the effect of the clearance between the plate and the wind tunnel side wall. For the efficiency of computation, half model was simulated and a symmetric boundary condition was applied on the center plane. Based on the preliminary design, a ground plate was designed, manufactured and tested at the Korea Aerospace Research Institute(KARI) wind tunnel. The measured pressure differences versus flap deflection angle agreed well with the predicted results.

• 한국지반신소재학회논문집
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• 제16권4호
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• pp.191-210
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• 2017

The concern study, present the results of experimental study on the performance of deep excavation by using image processing technique particle image velocimetry (PIV). The purpose of present study is to check the application of PIV for the successive ground deformation during deep excavation. To meet the objectives of concern study, a series of reduce scale model test box experiments are performed by considering the wall stiffness, ground water table effect and ground relative density. The results are presented in form of contour and vector plots and further based on PIV analysis wall and ground displacement profile are drawn. The results of present study, indicate that, the PIV technique is useful to demonstrate the ground deformation zone during the successive ground excavation as the degree of accuracy in PIV analysis and measured results with LVDT are within 1%. Further the vector and contours plot effectively demonstrate the ground behavior under different conditions and the PIV analysis results fully support the measured results.