• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.372-379
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• 2004

The model tests were conducted to assess the behavior characteristics of geogrid reinforced earth walls according to various surcharge loads and reinforcement spacing. The models were built in the box having dimension, 100cm tall, 140cm long, and 100cm wide. The reinforcement used was geogrid(tensile strength 2.26t/m). Decomposed granite soil(ML) was used as a backfill material. The LVDTs were installed on the model retaining walls to obtain the displacements of the facing. In the results, the maximum displacement of facing and tensile strain of geogrid was measured at 0.7H(H is wall height) from the bottom of reinforced wall.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1230-1232
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• 1999

In this research, ANN load model was built on results of field test using residential load, and then proposed ANN load model was applied to transient analysis. The results of this research are as follows. The first, component load modeling using ANN was implemented. The second, group load model was proposed by aggregation of component load. The third, proposed load model was applied to power system analysis. Therefore, Importance of load modeling and precise load modeling method was suggested in this paper.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.443-450
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• 2003

System identification techniques can be used to build a baseline modal model for a flawed structure that has no modal information on its as-built state. The accuracy of a system identification proposed by Stubbs and Kim is analyzed for plate-girder bridges and its impact on the accuracy of damage detection in those structures is also analyzed. A laboratory-scale model plate-girder is experimentally tested and the initial four bending modes are examined for certain damage scenarios. The performance of individual baseline modal models is assessed by detecting damage in the model structure.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.7
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• pp.23-32
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• 2004

A spatial simulation model for rural and urban sprawl phenomena was developed with GIS and cellular automata techniques. The model finds out built-up areas invading toward rural areas required for development of existing urban area. Probability of land use change for optimizing the development area was determined using a land suitability analysis method interfaced with GIS methods, based on several criteria in terms of geographic and accessibility factors such as slope of land and distance from city center. Weighting values of the criteria were quantified by an analytic hierarchy process method. For model applicability test, the parameters of criteria were calibrated based on the changes in time series land use data of the test city for 1986, 1996, and 2000, which were classified by remote sensing techniques. Simulated and observed areas in land use maps for city shape of 1996 showed good similarities with each other through a morphology verification method. The model enabled us to evaluate the spatial expansion phenomena of cities considering boundary conditions, and also to simulate land use planning for rural areas in urban fringe.

• Journal of the Korean Solar Energy Society
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• v.21 no.3
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• pp.51-60
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• 2001

A greenhouse equipped with latent heat storage system was built to obtain various thermal properties, such as greenhouse air temperature, soil surface temperature, energy flow in latent heat storage, etc., which could be used in validation of greenhouse numerical model to be developed in this study. This numerical model expressed with Newton-Raphson method was programed by C-language and utilized to simulate greenhouse thermal behavior. Greenhouse air temperature and soil surface temperature predicted by the greenhouse model developed in this study were very close to the measured data obtained through almost 3 years of experiment. Therefore, it is concluded that the greenhouse model developed and verified by measured data could be utilized for simulating various thermal behaviors of greenhouses equipped with latent heat storage system to be used for energy saving purposes.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.201-208
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• 2007

This paper is research results of investigating the elastic settlement behavior of the coastal caisson structure built on the sandy deposit by comparing results of centrifuge model experiments and those of existing methods of estimating elastic settlement. Basic soil property tests such as specific gravity test, grain size distribution test and organic content test with disturbed soil sampled from the site were carried out. The centrifuge experiment of model satisfying the required design criteria was performed under 50 of artificial accelerated gravitational force condition. The Centrifuge model experimental results were compared and analyzed with the current methods of estimating settlement based on the elastic modulus obtained from the results of odeometer tests and empirical methods from literature reviews.

• Steel and Composite Structures
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• v.25 no.1
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• pp.45-55
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• 2017

Stainless steel exhibits high ductility and strain hardening capacity in comparison with carbon steel widely used in constructions. To analyze the particular behaviour of stainless steel cover-plate joints, an experimental study was conducted. It showed large ductility and complex failure modes of the joints. A non-linear finite element model was developed to predict the main parameters influencing the behaviour of these joints. The results of this deterministic model allow us to built a meta-model by using the quadratic response surface method, in order to allow for efficient reliability analysis. This analysis is then applied to the assessment of design formulae in the currently used codes of practice. The reliability analysis has shown that the stainless steel joint design according to Eurocodes leads to much lower failure probabilities than the Eurocodes target reliability for carbon steel, which incites revising the resisting model evaluation and consequently reducing stainless steel joint costs. This approach can be used as a basis to evaluate a wide range of steel joints involving complex failure modes, particularly bearing failure.

• Membrane and Water Treatment
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• v.10 no.2
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• pp.149-154
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• 2019

The information matter-element system was built to assess safety of water source. Based on the thought of multiindex fusion, fuzzy matter-element model evaluating water source behavior was constructed by matter-element transform. This model can process comprehensively hydrogeological data, ecological environment, water pollution, surface disturbance, and so on. Water source safety behavior can be described by the qualitative and quantitative manners. According to the development trend of quantitative results, water source safety behavior can be expressed dynamically. As an example, the proposed method was used to assess safety status of 7 water sources in the region. The numerical example shows that the proposed method is feasible and effective, and the evaluation results are reasonable.

• Journal of Environmental Impact Assessment
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• v.20 no.4
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• pp.539-555
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• 2011

Newly constructed, high-rise dense building areas by urban development can cause changes in local wind fields. Wind fields were analyzed to assess the impact on the local meteorology due to the land use changes during the urban redevelopment called "Eunpyeong new town" in north-western Seoul using CFD_NIMR_SNU (Computational Fluid Dynamics, National Institute of Meteorological Research, Seoul National University) model. Initial value of wind speed and direction use analysis value of AWS (Automatic Weather Station) data during 5 years. In the case of the pre-construction with low rise built-up area, it was simulated that the spatial distribution of horizontal wind fields depends on the topography and wind direction of initial inflow. But, in the case of the post-construction with high rise built-up area, it was analyzed that the wind field was affected by high rise buildings as well as terrain. High-rise buildings can generate new circulations among buildings. In addition, small size vortexes were newly generated by terrain and high rise buildings after the construction. As high-rise buildings act as a barrier, we found that the horizontal wind flow was separated and wind speed was reduced behind the buildings. CFD_NIMR_SNU was able to analyze the impact of high-rise buildings during the urban development. With the support of high power computing, it will be more common to utilize sophisticated numerical analysis models such as CFD_NIMR_SNU in evaluating the impact of urban development on wind flow or channel.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.6
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• pp.566-576
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• 2003

Carbon-fiber reinforced plastics (CFRP) composite laminates often possess strong in-plane elastic anisotropy attributable to the fiber orientation and layup sequence. The layup orientation thus greatly influences its properties in a composite laminate. It could result in the part being rejected or discarded if the layup orientation of a ply is misaligned. A nondestructive technique would be very beneficial, which could be used to test the part after curing and to require less time than the optical test. In this paper, ultrasonic scanners were set out for different measurement modalities for acquiring ultrasonic signals as a function of in-plane azimuthal angle. The motorized scanner was built first for making transmission measurements using a pair of normal-incidence shear wave transducers. Another scanner was then built fer the acousto-ultrasonic configuration using contact transducers. A ply-by-ply vector decomposition model has been developed, simplified, and implemented for composite laminates fabricated from unidirectional plies. We have compared the test results with model data. It is found that strong agreement are shown between tests and the model developed in characterizing cured layups of the laminates.