• International Journal of Highway Engineering
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• v.11 no.1
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• pp.165-175
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• 2009

With the current move towards adopting mechanistic-empirical concepts in the design of pavement structures, state-of-the-art mechanistic analysis methodologies are needed to determine accurate pavement responses, such as stress, strain, and deformation. Previous laboratory studies of pavement foundation geomaterials, i.e., unbound granular materials used in base/subbase layers and fine-grained soils of a prepared subgrade, have shown that the resilient responses followed by nonlinear, stress-dependent behavior under repeated wheel loading. This nonlinear behavior is commonly characterized by stress-dependent resilient modulus material models that need to be incorporated into finite element (FE) based mechanistic pavement analysis methods to predict more realistically predict pavement responses for a mechanistic pavement analysis. Developed user material subroutine using aforementioned resilient model with nonlinear solution technique and convergence scheme with proven performance were successfully employed in general-purpose FE program, ABAQUS. This numerical analysis was investigated in predicted critical responses and domain selection with specific mesh generation was implemented to evaluate better prediction of pavement responses. Results obtained from both axisymmetric and three-dimensional (3D) nonlinear FE analyses were compared and remarkable findings were described for nonlinear FE analysis. The UMAT subroutine performance was also validated with the instrumented full scale pavement test section study results from the Federal Aviation Administration's National Airport Pavement Test Facility (FAA's NAPTF).

• Journal of Soil and Groundwater Environment
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• v.7 no.1
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• pp.41-51
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• 2002

Recently, domestic waste landfills are constructed sometimes on seashore area to provide large landfill area. In order to strengthen the foundation of landfills and to prevent the infiltration of leachate through the bottom, many cases of constructing cement hardened liners on seashore clays are found. In these cases, it is possible to have cracks in the hardened liners due to settlement with waste load since the stiffness of the hardened liner Is greater than that of clay liners. In this study, the capability of Self-Sealing and Self-Healing (SSSH) liner made with a seashore clay in the metropolitan landfill to prevent the percolation of water and leachate is examined using flexible-wall permeameter test and using uniaxial compression test. Applicability of SSSH to weathered granitic soil is also examined for self-sealing capabilities. The result of Flexible permeameter test for SSSH with the seashore clay showed that permeability obtained was lower than permeability criteria of Korean waste management law. The permeability and strength characteristics of SSSH with granitic soil and bentonite showed better results than with the seashore clay.

• Archives of design research
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• v.15 no.4
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• pp.391-398
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• 2002

This study attempts to suggest a new direction of the plastic arts education, first by examining a variety of cases in the admission policy depending on the existence of students' preeducation; and second, by analyzing the work process of students who were admitted. The flexible admission policy should be provided to select both groups of students: students with preeducation and students without preeducation. It is requested that the uniform selectional standard adopted by most universities should be changed into the diverse standards that can evaluate different educational back ground of students. This study will be helpful for the university professors to prepare for the new educational foundation and direction by enhancing the efficiency of teaching. This study also aims to suggest the curriculum and methods of the design education to provide the effective teaching of plastic arts and there by develop the better methods of education in this area.

• Earthquakes and Structures
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• v.18 no.4
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• pp.407-421
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• 2020

In-place analysis for offshore platforms is essentially required to make proper design for new structures and true assessment for existing structures, in addition to the structural integrity of platforms components under the maximum and minimum operating loads when subjected to the environmental conditions. In-place analysis have been executed to check that the structural member with all appurtenance's robustness have the capability to support the applied loads in either storm or operating conditions. A nonlinear finite element analysis is adopted for the platform structure above the seabed and pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The SACS software is utilized to calculate the dynamic characteristics of the platform model and the response of platform joints then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have significant effects in the results of the in-place analysis behavior. The most of bending moment responses of the piles are in the first fourth of pile penetration depth from pile head level. The axial deformations of piles in all load combinations cases of all piles are inversely proportional with penetration depth. The largest values of axial soil reaction are shown at the pile tips levels (the maximum penetration level). The most of lateral soil reactions resultant are in the first third of pile penetration depth from pile head level and approximately vanished after that penetration. The influence of the soil-structure interaction on the response of the jacket foundation predicts that the flexible foundation model is necessary to estimate the force responses demands of the offshore platform with a piled jacket-support structure well.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.33-42
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• 2006

Geosynthetics reinforced soil (GRS) walls with a flexible wall face allow deformation. GRS walls constructed on the weak ground change in both horizontal earth pressures on wall faces and the tensile stress of geosynthetics, affecting the backfill in time until the deformation of the backfill and the foundation is completed. However, there are few studies that were done to measure and analyze the horizontal earth pressures and geosynthetics deformation on GRS walls constructed on the soft ground for a long period of time. Two field GRS walls in this study are constructed on a shallow layer of a weak foundation to measure and analyze geostynthetics deformation, horizontal earth pressures, and pore water pressures for the duration of approximately 16 months. Strain gauges are used to measure geosynthetics deformation; this study specifically suggests a new method of measuring nonwoven geotextile using strain gauges. Most geosynthetics deformation occurred within a month after the construction of GRS walls. The maximum deformation measured for approximately 16 months appeared as follows: nowoven geotextile: 6.05%, woven geotextile: 2.92%, and geogrid: 2.33%. Pore water pressures on the GRS wall can be ignored; however, horizontal earth pressures on the bottom and the upper part of the wall face appear larger than earth pressures at rest.

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.66-76
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• 2004

This study is to compare and analyse the high school chemistry curriculum in Korea and Japan from the viewpoint of the structure, objectives, contents, teaching-learning method, and assessment plans. From the comparative analysis, we found some common and different aspects. The suggestive ideas which is useful for study of Korean science curriculum were deduced, such as more expansion of selective subjects and enhancing the guidance, more flexible teaching methods, enhancing the individualized instruction plans suitable to each student's condition, careful selection of educational contents and enhancing the base and foundation, and transition period.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1221-1230
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• 2008

Inflatable rubber dams are used for controlling flood, impounding water for recreations, preventing beach erosions, diverting water for irrigations, and generating hydropower. They are long, flexible, inflated with air, cylindrical structures on a rigid horizontal foundation such as concrete. The dam is modeled as an elastic shell inflated with air. The mechanical behaviors of the inflated dam model were investigated by using the finite element method. The analysis process such as One Way Coupling Fluid-Structure Interaction consists of two steps. First, the influences of the fluid side were investigated, viz, the shape changes of the inflated rubber dam due to the fluid motions was captured when the height of the dam was 30cm with air pressure 0.01MPa, at which the pressure distributions over the surface of the dam were calculated. And next, the structural deformations were calculated using the pressure distributions. The initial inlet velocity for flow field was set to 0.1m/s. The structural deformation behaviors were investigated. The final research goal is to develop a Korean Inflatable Rubber Dam to be used for generating small hydropower.

• Archives of design research
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• v.19 no.3 s.65
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• pp.31-44
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• 2006

With 'the improvement of brand image through the consolidation of the online and offline brand images' as the goal, the focus of this study lies in brand color. In order to analyze the differences between the website and offline image of a brand, as felt by the consumers, a survey on color image was conducted. Using the results of the survey as the foundation, a comparative analysis of online and offline color images was conducted, and the discrepancies between the two specified. Furthermore, solutions in creating websites that cultivate brand consolidation through color consolidation are presented. Using the thesis 'Research on the Color Strategy of Brand-name Coffees,' as a guide, and supplementing it with necessary improvements, this study presents three areas to consider when designing or managing websites for offline brands. First of all, color image is not static but variable, meaning that it appeals to the consumers differently, depending on change in other brands, trends, consumer point of view, etc. Thus, color image must be flexible. Secondly, overall brand image can be improved by its offline color. However, it should be realized that identical colors could produce different results online and off. Lastly, in general, the online image falls behind the offline image, in regard to color strategy. Therefore, more meticulous and carefully planned color design is necessary, as is the consideration of the unique and distinctive qualities of the World Wide Web.

• Earthquakes and Structures
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• v.2 no.3
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• pp.257-277
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• 2011

An evaluation is presented of the response of a 3-storey R/C structure during the destructive Lefkada earthquake of 14/08/2003. Key aspects of the event include: (1) the unusually strong levels of ground motion (PGA = 0.48 g, $SA_{max}$ = 2.2 g) recorded approximately 10 km from fault, in downtown Lefkada; (2) the surprisingly low structural damage in the area; (3) the very soft soil conditions ($V_{s,max}$ = 150 m/s). Structural, geotechnical and seismological aspects of the earthquake are discussed. The study focuses on a 3-storey building, an elongated structure of rectangular plan supported on strip footings, that suffered severe column damage in the longitudinal direction, yet minor damage in the transverse one. Detailed spectral and time-history analyses highlight the interplay of soil, foundation and superstructure in modifying seismic demand in the two orthogonal directions of the building. It is shown that soil-structure interaction may affect inelastic seismic response and alter the dynamic behavior even for relatively flexible systems such as the structure at hand.

• Wind and Structures
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• v.14 no.2
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• pp.85-112
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• 2011

Wind turbine structures are long slender columns with a rotor and blade assembly placed on the top. These slender structures vibrate due to dynamic environmental forces and its own dynamics. Analysis of the dynamic behavior of wind turbines is fundamental to the stability, performance, operation and safety of these systems. In this paper a simplied approach is outlined for free vibration analysis of these long, slender structures taking the soil-structure interaction into account. The analytical method is based on an Euler-Bernoulli beam-column with elastic end supports. The elastic end-supports are considered to model the flexible nature of the interaction of these systems with soil. A closed-form approximate expression has been derived for the first natural frequency of the system. This new expression is a function of geometric and elastic properties of wind turbine tower and properties of the foundation including soil. The proposed simple expression has been independently validated using an exact numerical method, laboratory based experimental measurement and field measurement of a real wind turbine structure. The results obtained in the paper shows that the proposed expression can be used for a quick assessment of the fundamental frequency of a wind turbine taking the soil-structure interaction into account.