• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.561-568
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• 2003

The protection of adjacent structures in urban excavation has been an important issue. But the research on the interaction between ground movements and adjacent structure has been scarce, therefore this study was necessitated. Current design practice for the prediction of excavation-induced ground movements heavily rely on empirical method. In this study, damage levels of brick building are examined closely by means of angular distortion, deflection ratio, horizontal strain. The results of numerical analysis indicated that the movement of actual building was 60∼65% of the ground movement, while angular distortion was 45∼65%. Also numerical analysis for the assessment of brick building can be applied to the building protection at various construction stages.

• 자원환경지질
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• 제33권6호
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• pp.557-563
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• 2000

Subsidence hazard has never been considered seriously until recent yews in Korea, although its socioeconomic impact on Korea becomes more and more enormous. There have been a few studies for the application of GIS analysis technique to the prediction of subsidence hazard. For GIS analysis, several factors, which are represented by coverage, are considered and selected for building a GIS model. Numerical method was used to quantify the importance of each factor in GIS model and the result from numerical modeling using FLAC was compared with that from previous research based on empirical methods. Analysis in 3-D needs more computer resources (i.e. memory). Therefore that in 2.5-D was considered to overcome the problem. Not only maximum vertical subsidence but also maximum horizontal strain and maximum slope have been considered for the assessment of subsidence hazard. The model can be easily modified for the purpose of applications in any subsidence area, especially cavern or abandoned mines under thick soil layer.

• Nuclear Engineering and Technology
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• 제42권3호
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• pp.279-296
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• 2010

For the analysis of transient two-phase flows in nuclear reactor components, a three-dimensional thermal hydraulics code, named CUPID, has been developed. The CUPID code adopts a two-fluid, three-field model for two-phase flows, and the governing equations were solved over unstructured grids, which are very useful for the analysis of flows in complicated geometries. To obtain numerical solutions, the semi-implicit numerical method for the REALP5 code was modified for an application to unstructured grids, and it has been further improved for enhanced accuracy and fast running. For the verification of the CUPID code, a set of conceptual problems and experiments were simulated. This paper presents the flow model, the numerical solution method, and the results of the preliminary assessment.

• 방사성폐기물학회지
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• 제6권4호
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• pp.283-296
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• 2008

중 저준위 방사성폐기물 처분 부지 건설될 지하 시설물을 고려하여 지하수 유동 모델링을 수행하였으며, 처분 안전성 평가를 위해 건설 중 지하 시설물로의 지하수 유입량, 처분장 폐쇄 후 처분 사일로를 통과하는 지하수 유동량 및 처분 사일로에서 배출 지역까지의 지하수 유동로에 대한 이동 거리 및 단위 유량에 대한 입력 인자를 도출하였다. 처분장 건설 중 지하수 유입량 및 폐쇄 후 지하수의 유동량은 처분 심도에서 존재하는 다수의 투수성 구조 영역에 의해 영향을 받아 10가지 경우에서 각각 상이한 결과를 나타내었다. 지하수 유동로에 대한 지하수의 이동 거리 및 단위 유량에 대한 결과도 지하수의 유동로에 존재하는 투수성 구조 영역에 영향을 받는 것으로 분석된다. 가상의 인간 침입 시나리오를 위해 우물 시나리오를 가정하여 지하수 유동 모델링을 수행하였으며, 그 결과를 이용하여 처분 안전성 평가와 관련된 입력 인자를 도출하였다.

• Nuclear Engineering and Technology
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• 제42권2호
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• pp.145-150
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• 2010

The paper is describing work being developed in the frame of a 5-year IAEA Coordinated Research Programme (CRP) started in late 2005. Participants gained knowledge of modelling methodologies and experience in the development and use of rather sophisticated simulation tools in support of site characterization and performance assessment calculations. These goals were achieved by a coordinated effort, in which the advantages and limitations of numerical models are examined and demonstrated through a comparative analysis of simplified, illustrative test cases. This knowledge and experience should help them address these issues in their own country's nuclear waste program. Coordination efforts during the first three years of the project aimed at enabling this transfer of expertise and maximizing the learning experience of the participants as a group. This was accomplished by identifying common interests of the participants (i.e., Process Modelling and Total System Performance Assessment methodology), and by defining complementary tasks that are solved by the members. Synthesis of all available results by comparative assessments is planned in the coming months. The project will be completed end of 2010. This paper is summarizing activities up to November 2009.

• Wind and Structures
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• 제20권1호
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• pp.59-74
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• 2015

A coupled model system for Wind Resource Assessment (WRA) was studied. Using a mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, global-scale data were downscaled to the inner nested grid scale (typically a few kilometers), and then through the coupling Computational Fluid Dynamics (CFD) mode, FLUENT. High-resolution results (50 m in the horizontal direction; 10 m in the vertical direction below 150 m) of the wind speed distribution data and ultimately refined wind farm information, were obtained. The refined WRF/FLUENT system was then applied to assess the wind resource over complex terrain in the northern Poyang Lake region. The results showed that the approach is viable for the assessment of wind energy.

• Earthquakes and Structures
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• 제16권6호
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• pp.705-714
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• 2019

Seismic assessment of underground structures is one of the challenging problems in engineering design. This is because there are usually many sources of uncertainties in rocks and probable earthquake characteristics. Therefore, for decreasing of the uncertainties, seismic response of underground structures should be evaluated by sufficient number of earthquake records which is scarcely possible in common seismic assessment of underground structures. In the present study, a practical risk-based approach was performed for seismic risk assessment of an unsupported tunnel. For this purpose, Incremental Dynamic Analysis (IDA) was used to evaluate the seismic response of a tunnel in south-west railway of Iran and different analyses were conducted using 15 real records of earthquakes which were chosen from the PEER ground motion database. All of the selected records were scaled to different intensity levels (PGA=0.1-1.7 g) and applied to the numerical models. Based on the numerical modeling results, seismic fragility curves of the tunnel under study were derived from the IDA curves. In the next, seismic risk curve of the tunnel were determined by convolving the hazard and fragility curves. On the basis of the tunnel fragility curves, an earthquake with PGA equal to 0.35 g may lead to severe damage or collapse of the tunnel with only 3% probability and the probability of moderate damage to the tunnel is 12%.

• 대한토목학회논문집
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• 제26권2A호
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• pp.351-361
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• 2006

이 연구에서는 원형 철근콘크리트 교각의 횡방향 철근에 따른 내진성능평가를 위한 비선형 유한요소해석 기법을 제시하였다. 이 논문에서는 원형 철근콘크리트 교각의 이력거동의 예측에 근거한 손상지수를 제시하였다. 손상지수는 지진하중하의 원형 철근콘크리트 교각의 손상을 수치적으로 정량화하는 방법으로서 제안되었다. 제안한 해석기법을 실험된 철근콘크리트 교각에 적용하여 비교, 분석하였다. 제안된 해석기법은 조사된 실험체에 대하여 하중단계에 따라 내진성능을 정확하게 예측하였다.

• 한국통신학회논문지
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• 제40권6호
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• pp.1081-1090
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• 2015

This work proposes a theoretic framework for the performance assessment of an access point in the IP network that accommodates MD (Machine Data) and HD (Human Data). First, we investigate typical resource allocation methods in LTE for MD and HD. After that we carry out a Max-Min analysis about the surplus and deficiency of network resource seen from MD and HD. Finally, we evaluate the performance via numerical experiment.

• Earthquakes and Structures
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• 제15권4호
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• pp.431-441
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• 2018

This study provides fragility-based assessment of seismic performance of reinforced concrete bridges. Seismic fragility curves were created using nonlinear analysis (NA) and artificial neural networks (ANNs). Nonlinear response history analyses were performed, in order to calculate the seismic performances of the bridges. To this end, 306 bridge-earthquake cases were considered. A multi-layered perceptron (MLP) neural network was implemented to predict the seismic performances of the selected bridges. The MLP neural networks considered herein consist of an input layer with four input vectors; two hidden layers and an output vector. In order to train ANNs, 70% of the numerical results were selected, and the remained 30% were employed for testing the reliability and validation of ANNs. Several structures of MLP neural networks were examined in order to obtain suitable neural networks. After achieving the most proper structure of neural network, it was used for generating new data. A total number of 600 new bridge-earthquake cases were generated based on neural simulation. Finally, probabilistic seismic safety analyses were conducted. Herein, fragility curves were developed using numerical results, neural predictions and the combination of numerical and neural data. Results of this study revealed that ANNs are suitable tools for predicting seismic performances of RC bridges. It was also shown that yield stresses of the reinforcements is one of the important sources of uncertainty in fragility analysis of RC bridges.