• Structural Engineering and Mechanics
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• v.43 no.3
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• pp.371-394
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• 2012

Accurate finite element (FE) models are needed in many applications of Civil Engineering such as health monitoring, damage detection, structural control, structural evaluation and assessment. Model accuracy depends on both the model structure (the form of the equations) and the model parameters (the coefficients of the equations), and can be generally improved through that process of experimental reconciliation known as model updating. However, modelling errors, including (i) errors in the model structure and (ii) errors in parameters excluded from adjustment, may bias the solution, leading to an updated model which replicates measurements but lacks physical meaning. In this paper, an application of ambient-vibration-based model updating to a large-scale benchmark prototype of a building structure is reported in which both types of error are met. The error in the model structure, originating from unmodelled secondary structural elements unexpectedly working as resonant appendages, is faced through a reduction of the experimental modal model. The error in the model parameters, due to the inevitable constraints imposed on parameters to avoid ill-conditioning and under-determinacy, is faced through a multi-model parameterization approach consisting in the generation and solution of a multitude of models, each characterized by a different set of updating parameters. Results show that modelling errors may significantly impair updating even in the case of seemingly simple systems and that multi-model reasoning, supported by physical insight, may effectively improve the accuracy and robustness of calibration.

• Journal of the Korean housing association
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• v.25 no.1
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• pp.23-32
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• 2014

This research progressed space evaluation test with 3D simulation for exterior space of detached housing area among the Seoul spaces of child sex offense in 2010. Based on changing analysis on natural surveillance by spatial changes of each physical element, the purpose is to suggest effective construction planning measure for preventing child sex offense. The results of research are as follows. First, natural surveillance of space's height differences and width differences were compared and analyzed. As the result, footpath shows that stairs of slope didn't make lots of effects on visual block, not block of spatial moving, because of the difference of stair height. Also, in case of parking space, visual connection with footpath is expanded when designing pilotis rather than heightening floor height, so activities of exterior people could be seen more easily. Therefore, natural surveillance was higher. Second, natural surveillance of architectural elements by changes of footpath' width was compared and analyzed. As the result, openness of footpath should be secured rather than openness of architectural element. And, planning autonomy of architectural form could be more expanded when securing openness of footpath.

• Coupled systems mechanics
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• v.3 no.3
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• pp.267-289
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• 2014

A proper physical modeling of infilled building frame-foundation beam-soil mass interaction system is needed to predict more realistic and accurate structural behavior under static vertical loading. This is achieved via finite element method considering the superstructure, foundation and soil mass as a single integral compatible structural unit. The physical modelling is achieved via use of finite element method, which requires the use of variety of isoparametric elements with different degrees of freedom. The unbounded domain of the soil mass has been discretized with coupled finite-infinite elements to achieve computational economy. The nonlinearity of soil mass plays an important role in the redistribution of forces in the superstructure. The nonlinear behaviour of the soil mass is modeled using hyperbolic model. The incremental-iterative nonlinear solution algorithm has been adopted for carrying out the nonlinear elastic interaction analysis of a two-bay two-storey infilled building frame. The frame and the infill have been considered to behave in linear elastic manner, whereas the subsoil in nonlinear elastic manner. In this paper, the computational methodology adopted for nonlinear soil-structure interaction analysis of infilled frame-foundation-soil system has been presented.

• Advances in aircraft and spacecraft science
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• v.3 no.1
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• pp.95-112
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• 2016

This paper presents the free vibration analysis of damaged beams by means of 1D (beam) advanced finite element models. The present 1D formulation stems from the Carrera Unified Formulation (CUF), and it leads to a Component-Wise (CW) modelling. By means of the CUF, any order 2D and 1D structural models can be developed in a unified and hierarchical manner, and they provide extremely accurate results with very low computational costs. The computational cost reduction in terms of total amount of DOFs ranges from 10 to 100 times less than shell and solid models, respectively. The CW provides a detailed physical description of the real structure since each component can be modelled with its material characteristics, that is, no homogenization techniques are required. Furthermore, although 1D models are exploited, the problem unknown variables can be placed on the physical surfaces of the real 3D model. No artificial surfaces or lines have to be defined to build the structural model. Global and local damages are introduced by decreasing the stiffness properties of the material in the damaged regions. The results show that the proposed 1D models can deal with damaged structures as accurately as a shell or a solid model, but with far lower computational costs. Furthermore, it is shown how the presence of damages can lead to shell-like modal shapes and torsional/bending coupling.

• Journal of the Korean association of regional geographers
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• v.21 no.3
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• pp.529-552
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• 2015

This study aims to analyze the placeness of Gwangju Art Street and the changing process of the street, looked through the experiences of life subjects living in this street. For this purpose, at first, history before art street was designated was traced by reviewing geographical characteristics and spatial transformation of the Art Street with the trend of Gwangju art scene and economic political situation. And then, in order to analyze the placeness of Gwangju Art Street, formation factors of placeness are extracted into physical element, behavior element and semantic element. Physical element and behavior element were analyzed through in-depth interview and data analysis for individual and microscopic historical process of life subjects being experienced in the street that is contrary to policy and plan. Finally, a semantic element was identified through questionnaire as to how people recognize current art street through a history being experienced as a venue of conflict of meaning. It is implied that bottom up place making policies that may connect context of the formation of placeness with the viewpoint of life subject in the Art Street is required to be presented now.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.2
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• pp.139-147
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• 2016

Performances of urethane packing in the hydraulic breaker were analyzed using a finite element method. Because of high temperature and high pressure in the hydraulic breaker, it is better to use urethane rather than rubber as a packing material. We obtained the physical properties of urethane at elevated temperature by the tensile test. We analyzed buffer seal and U-packing maintaining the pressure and preventing oil leakage. Deformation, stress distribution, contact length, contact pressure of packing at each pressure step were obtained using finite element analysis. As the temperature increases, stress and contact force tend to decrease at low pressure. As the gap between piston and cylinder increases, contact length and contact forces decrease. Consequently, it is possible to design the packing section using these analyses, and construct a system to predict the possibility of oil leakage in the hydraulic breaker.

• Korean Institute of Interior Design Journal
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• v.18 no.5
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• pp.12-20
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• 2009

Memory and schema are very similar in terms of human accumulated mental and physical experiences. However, while memory has more personal aspect, schema discussed in this paper has more collective aspect. Schema has been developed through different generations and times, and has become a specific psychological or visual element(s) that can be applied to various fields, such as all, design and architecture. This study focuses on Aldo Rossi's architectural design characteristics based on his 'Autobiographical Concept' as well as personal schema. 'Autobiographical Concept' is the crucial structure supporting Aldo Rossi's distinctive formalization and spatialization. 4 case projects were comparatively analyzed by the 5 elements included in 'Autobiographical Concept'. It was not easy to relate each element to a specific design aspect because the 5 elements are somehow theoretically and conceptually inter-connected each other. Even though it is very difficult to directly relate a conceptual element with a real spatial element, it is found that the 5 elements have some differences in the spatialization process. Thus, in the conclusion, this study attempted to show the unique characteristics of the Aldo Rossi's architectural design process based on his 'Autobiographical Concept'.

• Korean Institute of Interior Design Journal
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• v.14 no.6 s.53
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• pp.193-201
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• 2005

In this study we analyzed and interpreted the phenomenologlcal characteristics and meanings of water space in religious architecture through field studies and phenomenologlcal approaches, focusing on the religious architecture Introducing water space in contemporary architecture. The phenomenological experience elements of the research ate light, time, place and context. As the results of this study, first, light as a phenomenological element not only induces a contrast and change between light and the shadow in architectural space and various changes of light in inner space, but also operates as an element which expresses building features outward with time. Second, time as a phenomenological perception experience makes us feel changes of the environment and physical properties and experience space visually and physically. The continuity of time shows the change of a day, night and daytime and seasons. Third, water space makes the sense of place more remarkable, connected closely with surrounding nature In outer space, and creates a new space. Fourth, water space is a contextual element which harmonizes with surrounding environment by connecting surrounding natural environment with architectural space. Fifth, water space in religious architecture is a symbolic and central element, and emphasizes the atmosphere of architectural space. In addition, it makes the people who experience water space perceive the place by triggering sensitive response.

• Journal of Powder Materials
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• v.16 no.2
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• pp.85-90
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• 2009

Magnesium and its alloys are attractive as light weight structural/functional materials for high performance application in automobile and electronics industries due to their superior physical properties. In order to obtain high quality products manufactured by the magnesium powders, it is important to control and understand the densification behavior of the powders. The effect of the sheath surrounding the magnesium powders on the plastic deformation and densification behavior during equal channel angular pressing was investigated in the study by experimental and the finite element methods. A modified version of Lee-Kim's plastic yield criterion, notably known as the critical relative density model, was applied to simulate the densification behavior of magnesium powders. In addition, a new approach that extracts the mechanical characteristics of both the powder and the matrix was developed. The model was implemented into the finite element method, with which powder compaction under equal channel angular pressing was simulated.

• Computers and Concrete
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• v.6 no.2
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• pp.133-153
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• 2009

Discrete element modeling (DEM) in concrete technology is concerned with design and use of models that constitute a schematization of reality with operational potentials. This paper discusses the material science principles governing the design of DEM systems and evaluates the consequences for their operational potentials. It surveys the two families in physical discrete element modeling in concrete technology, only touching upon probabilistic DEM concepts as alternatives. Many common DEM systems are based on random sequential addition (RSA) procedures; their operational potentials are limited to low configuration-sensitivity features of material structure, underlying material performance characteristics of low structure-sensitivity. The second family of DEM systems employs concurrent algorithms, involving particle interaction mechanisms. Static and dynamic solutions are realized to solve particle overlap. This second family offers a far more realistic schematization of reality as to particle configuration. The operational potentials of this family involve valid approaches to structure-sensitive mechanical or durability properties. Illustrative 2D examples of fresh cement particle packing and pore formation during maturation are elaborated to demonstrate this. Mainstream fields of present day and expected application of DEM are sketched. Violation of the scientific knowledge of to day underlying these operational potentials will give rise to unreliable solutions.