• Steel and Composite Structures
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• v.19 no.4
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• pp.953-966
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• 2015

Carbonation depth was verified in 40 points of two 57 years old concrete viaducts. Field testing (phenolphthalein spraying) was performed on the structures. Data obtained were statistically analyzed by the Kolmogrov-Smirnov's test, one-way analysis of variance (ANOVA's test), and Fisher's method. The results revealed significant differences between maximum carbonation depths of different elements of the same concrete structure. Significant differences were also found in the carbonation of different concrete structures inserted in the same macroclimate. Microclimatic factors such as temperature and local humidity, sunshine, wind, wetting and drying cycles, among others, may have been responsible by the behavior of carbonation in concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.141-142
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• 2019

As part of the recent low-energy policy, insulation standards for buildings are increasing every year. In addition, the conventional styrofoam heat insulation material has a problem in that the thickness of the heat insulation material to achieve the standard heat transmission rate is rapidly increased. Although the risk of spreading the structure vulnerable to fire due to insufficient spacing between buildings due to thickened insulation is increasing, the high cost of high efficiency insulation is difficult to solve. On the other hand, it is known that the method to be used as a formwork using insulation is excellent in cost reduction effect by reducing the amount of formwork used and simplifying the subsequent insulation work. The purpose of this study is to evaluate the strength characteristics of multi - layered insulation materials with appropriate strength by reducing the thickness of the insulation by appropriately combining high performance phenolic foam insulation and styrofoam insulation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.19-20
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• 2015

Building exterior wall's energy loss is very high rate comparing to all part of a buildings. And it account for upper 40% of cooling and heating load. So many studies conducted improving insulation performance of building's exterior, appeared about sandwich insulation wall which could be gaining merit of traditional insulation method those are exterior insulation and interior insulation. In this study, we inform structural performance of sandwich insulation wall for RC wall. For this, first, we define each wall's role and design sandwich insulation wall. At last, analyze structural performance of sandwich insulation wall. This study can contribute to apply it safely where side wall which toilet, stair area, etc.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.130-131
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• 2019

As part of recent low-energy policies, thermal insulation standards for buildings are being tightened every year. In addition, the conventional styrofoam insulating material has a problem that the thickness of the heat insulating material to achieve a standard heat permeability is rapidly increased. Due to the thick insulation, there is a high risk of spreading vulnerable structures such as fire due to lack of space between buildings. On the other hand, the method of using the insulation as a formwork is known to be excellent cost saving effect through the reduction of the formwork usage and the simplification of the external insulation work. In order to solve this problem, this study aims to fabricate a multi-layered insulator that combines high-performance phenolic foam insulation and styrofoam insulation and evaluate the deflection characteristics for use as formwork.

• Advances in concrete construction
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• v.17 no.4
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• pp.187-210
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• 2024

Cantilever structures demonstrate diverse nonlocal effects, resulting in either stiffness hardening or dynamic softening behaviors, as various studies have indicated. This research delves into the free and forced vibration analysis of rotating nanoscale cylindrical beams and tubes under external dynamic stress, aiming to thoroughly explore the nonlocal impact from both angles. Utilizing Euler-Bernoulli and Reddy beam theories, in conjunction with higher-order tube theory and Hamilton's principle, nonlocal governing equations are derived with precise boundary conditions for both local and nonlocal behaviors. The study specifically examines two-dimensional functionally graded materials (2D-FGM), characterized by axially functionally graded (AFG) and radial porosity distributions. The resulting partial differential equations are solved using the generalized differential quadrature element method (GDQEM) and Newmark-beta procedures to acquire time-dependent results. This investigation underscores the significant influence of boundary conditions when nonlocal forces act on cantilever structures.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.337-349
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• 2009

In recent years, the cutting and banking areas along the railway in Korea are exposed to the erosion problem during every year. The reinforcement is a composite construction material in which the strength of engineering fill is enhanced by the addition of strong tensile reinforcement in many different types. Various problems of the railway infrastructure have occurred due to the differential settlement, frost heaving, mud pumping, lack of bearing capacity, partially loss of embankment. In advanced countries, railway roadbed reinforcement is applied to solve these problems on railway roadbed. This paper presents the solution of such problems by means of the engineering works incorporated with railway reinforcement infrastructures such as geotextile bag method, existing grouting method, geocell, reinforced earth, soil nailing and so on.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1275-1280
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• 2009

In recent bridge design, studies on application of external prestress have actively been conducted. When prestress is applied to steel structures, the limit value of elastic strain with large load increases with reduction of steels, this method is economic in cost. According to study by Brodka (1969), steel plate bridges with prestress has an effect on cost saving of about 15% compared with structures without prestress. For that reason, our country recently adopted this method in construction of temporary bridges and various engineering technologies have been developed which made stress correction, droop correction and long-span construction possible with relatively small cross sections. This study verifies the method of application of prestress in temporary steel structures, the influence of high-strength tendon arrangement and the effects of composite structures of steel plates and high-strength tendons based on existing method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.468-477
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• 2019

This study analyzed the major contents and results of revision through an analysis of the specifications and the field survey to revise the construction cost calculation criteria. The result of the survey found that the background processing difficulty was reduced due to an improvement of the quality level of the field floor, and the enhancement of the material's function brought a decrease in construction time and the application of various construction methods. In addition, the application of combined waterproofing methods using more than one material was increasing and the productivity differed according to the site and location. Based on these results, waterproof items were subdivided and applied to the composite construction method, and the input items were differentiated according to the material and construction method. The adequacy of the construction calculation criteria was ensured by presenting the criteria classified according to the construction area, and deleting the items that are not applicable and amending them to make them suitable for the specifications by reflecting the actual conditions of the construction on the site.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.481-490
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• 2005

This paper summarizes the full-scale test results on the CFT column-to-flat plate connections subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building construction practice due to its various structural and construction advantages. Constructing an underground parking floor as a flat plate system is often regarded as essential for both cost savings and rapid construction. Efficient details for CFT-column-to-flat-plate connections have not been proposed yet, however, and their development is urgently needed. Based on some strategies that maximize economical field construction, several connecting schemes were proposed and tested based on a full-scale model. The test results showed that the proposed connection details can exhibit punching shear strength and connection stiffness comparable to or greater than those of their R/C flat plate counterpart.