• Advances in concrete construction
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• v.16 no.6
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• pp.277-290
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• 2023

In order to study the mechanical properties of basalt fiber reinforced ultra-fine fly ash concrete (BFUFARC), the effects of ultra-fine fly ash (UFA) content, basalt fiber content, basalt fiber length and water reducing agent content on the compressive strength, splitting tensile strength and flexural strength of the composite material were studied through experimental and theoretical analysis. Also, a scanning electron microscope (SEM) was employed to analyze the mesoscopic structure in the fracture surface of composite material specimens at magnifications of 500 and 3500. Besides, the energy release rate (G_c) and surface free energy (γ_s) of crack tip cracking on BFUFARC in different basalt fiber content were studied from the perspective of fracture mechanics. Further, the cracking resistance, reinforcement, and toughening mechanisms of basalt fibers on concrete substrate were revealed by surface free energy of BFUFARC. The experimental results indicated that basalt fiber content is the main influence factor on the splitting tensile strength of BFUFARC. In case that fiber content increased from 0 to 0.3%, the concrete surface free energy at the tip of single-sided crack showed a trend of increased at first and then decreased. The surface free energy reached at maximum, about 3.59 × 10^-5 MN/m. During the process of increasing fiber content from 0 to 0.1%, G_C-2_γS showed a gradually decreasing trend. As a result, an appropriate amount of basalt fiber can play a preventing cracking role by increasing the concrete surface free energy, further effectively improve the concrete splitting tensile performance.

• Journal of Theoretical and Applied Mechanics
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• v.1 no.1
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• pp.1-27
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• 1995

In this paper a finite element method for free-surface problems is described. the method is based on two different forms of Hamilton's principle. To test the present computational method two specific wave problems are investigated; the dispersion relations and the nonlinear effect for the well-known solitary waves are treated. The convergence test shows that the present scheme is more efficient than other existing methods, e.g. perturbation scheme.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.1
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• pp.69-79
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• 2004

This Paper examines theoretical terrains and design strategies of landscape urbanism which is an emerging hybrid field at the intersection of architecture, landscape architecture, and urbanism. Landscape urbanism offers alternative approaches for theory, education, and practice in contemporary landscape architecture. It views the emergent urban complex sites-post-industrial sites, landfill, brownfield, urban void, etc., not as a weakness, but as a strength. Landscape urbanism poses an understanding of landscape as an element of urban infrastructure. In this sense, the landscape is seen in the context of contemporary urban development and public works. As a complex amalgam, landscape urbanism is more than a design style it is an ethos, an attitude, a way of thinking and acting. We can chart the main characteristics of landscape urbanism such as horizontality and surface, infrastructure, process, technique, and ecology. Multilayered examples of landscape urbanism can be seen in several experimental practices such as worts of Rem Koolhaas, MVRDV, Adriaan Geuze/West 8, James Comer, etc. It is possible to summarize the productive strategies for landscape urbanism as follows : thickening, folding, new materials, nonprogrammed use, impermanence, and movement.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.33-38
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• 2012

The aim of this experimental study was to analyze the effect of the shape parameters and chamber pressure of a land-based oscillating water column (OWC) in regular incident waves. The magnitude of the free surface elevations inside the chamber was measured in a two-dimensional wave tank for various chamber skirt drafts and bottom slope angles. The surface elevations were also measured under both open chamber and partially open chamber conditions. From these measurements, the optimum shape of the OWC device could be predicted for the maximum wave energy conversion efficiency. It was found that the resonance frequency of the OWC system associated with incident waves moved toward the long wave region with increments of the draft of the chamber skirt and bottom slope. The behavior of the free surface elevation inside the chamber was also found to be dependent on the chamber pressure.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.38-42
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• 1999

Average moisture content of 30mm-thick Korean red pine(Pinus densiflora) was estimated nondestructively and continuously using surface temperature rise by radiation heating and moisture gradient profile in wood. The surface temperature rises increased as surface moisture contents decreased and good relationships were found between surface moisture contents and surface temperature rises at three different feed speeds of 10, 20 and 30 m/min. Average moisture content could be described as a function of surface moisture content and wood thickness.

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.114-120
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• 2013

A superhydrophobic surface means that the contact angle between the solid surface and a water droplet is more than $150^{\circ}$. Materials with a superhydrophobic surface have a self-cleaning function because of the Lotus effect, in which water is not absorbed by the material but rolls off of it. If such a Lotus effect can be applied to the surface of underwater vessels, submarines, torpedos, and so on, enhanced vessels can be made based on this lubricant effect reducing the friction coefficient for the liquid. Because polymer composites can be easily applied in various nanotechniques, they are more advantageous than conventional materials like iron in terms of a superhydrophobic surface. Furthermore, a superhydrophobic surface bring enhanced anticorrosion and ecotechnology because no paint is needed on underwater vessels.

• Journal of The Korea Institute of Healthcare Architecture
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• v.21 no.1
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• pp.67-76
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• 2015

Purpose : The current tactile walking surface indicators have not been easily accessible to blind and vision-impaired people due to unexpected variation of walking environment and walking behavior of transportation poor. Moreover, those indicators frequently cause the inconvenience to transportation users' walking. Thus, this study aims to investigate the improvement of tactile walking surface indicators, by comparing and analyzing findings from the relevant research. Results from this study contribute to suggest the better standard criteria of tactile walking surface indicators for transportation users, especially blind and vision-impaired people, the handicapped, the child and the elderly and weak, providing the secure and convenient circumstance for walking. Method : This study presents the problems about the standard criteria of tactile walking surface indicators via the examination of finding from the past studies. For example, we examine all standard criteria, focusing on shapes, colors and qualities of materials used for Tactile Walking Surface Indicators. Then, the present study suggests the improvement of standard, which apply to the current walking environment practically and reasonably. Results : To improve the current condition of tactile walking surface indicators, the analysis on international and domestic standard criteria need to be conducted. Findings from these analyses helps to suggest the better criteria for the interval between projecting points of tactile walking surface indicators, effective perceived range of walking road, and the brightness contrast between tactile walking surface indicators and finishing materials. Implication : The suggested standard criteria of tactile walking surface indicators need to be tested by transportation users, and the practical instructions of establishing tactile walking surface indicators should also be developed.

• KIEAE Journal
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• v.15 no.3
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• pp.65-74
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• 2015

Purpose: This study is to propose a methodology for the formation of space according to the integration of structural concept and architectural concerns in the contemporary era. Beginning with researching on the theoretical fundamentals about surface-structure, it introduces several architectural examples to analyze its own structural form and spatial characteristics, and finally simulates a model for the formation of space through a real work. Method: The study is partially based on the Executive Architectural Project for 'Village of Spring' in Seocheon, which was planned in 2008 to suggest a strategic settlement layout for urban regeneration, and completed in 2012. Making architectural vocabularies permeated into surface-structure, throughout the design process of initially pursued concepts to the design development stage, we could encounter a new type of innovative space formation. It shows that the structure is one of most useful means for the realization of architectural concepts, and a design itself. Result: The expected result of the study intends to enhance the relationship between spatial formation and surface-structure, also ultimately to produce a structural system as 'space generator' to fulfill the social needs and its requirements.

• Wind and Structures
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• v.24 no.3
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• pp.287-306
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• 2017

In the present study, a new assessment simulation of ride safety based on a new wind-traffic-pavement-bridge coupled vibration system is developed considering stochastic characteristics of traffic flow and bridge surface. Compared to existing simulation models, the new assessment simulation focuses on introducing the more realistic three-dimensional vehicle model, stochastic characteristics of traffic, vehicle accident criteria, and bridge surface conditions. A three-dimensional vehicle model with 24 degrees-of-freedoms (DOFs) is presented. A cellular automaton (CA) model and the surface roughness are introduced. The bridge deck pavement is modeled as a boundless Euler-Bernoulli beam supported on the Kelvin model. The wind-traffic-pavement-bridge coupled equations are established by combining the equations of both the vehicles in traffic, pavement, and bridge using the displacement and interaction force relationship at the patch contact. The numerical simulation shows that the proposed method can simulate rationally useful assessment and prevention information for traffic, and define appropriate safe driving speed limits for vulnerable vehicles under normal traffic and bridge surface conditions.

• Journal of Ocean Engineering and Technology
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• v.37 no.3
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• pp.89-98
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• 2023

Analyzing the interactions of free surface waves caused by a submerged-body movement is important as a fundamental study of submerged-body motion. In this study, a two-dimensional mini-towing tank was used to tow an underwater body for analyzing the generation and propagation characteristics of free surface waves. The magnitude of the maximum wave height generated by the underwater body motion increased with the body velocity at shallow submerged depths but did not increase further when the generated wave steepness corresponded to a breaking wave condition. Long-period waves were generated in the forward direction as the body moved initially, and then short-period waves were measured when the body moved at a constant velocity. In numerical simulations based on potential flow, the fluid pressure changes caused by the submerged-body motion were implemented, and the maximum wave height was accurately predicted; however, the complex physical phenomena caused by fluid viscosity and wave breaking in the downstream direction were difficult to implement. This research provides a fundamental understanding of the changes in the free surface caused by a moving underwater body.