• Journal of the Korea Institute of Building Construction
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• v.8 no.6
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• pp.123-129
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• 2008

The purpose of this study is to test performances of 14 types of root barrier materials by applying testing plant: and soils suitable for weather and natural features of Korea. For testing Plants, Plioblastus pygmaed Mitford A and Pyracantha angustifolia have been selected. For testing soil, mixture of pearlite and peat moss in 3:1 ratio Testing container has been fabricated with duplicated structure having inner and outer containers. And the outer container has 2 hinges on its side wall to allow opening and closing. Wet rock wool with 50mm in thickness has been inserted between inner and outer containers to allow root to penetrate through root barrier material and continue to grow. We planted 12 Plioblastus pygmaed Mitford A. and 4 Pyracantha angustifolia per one testing container. Three testing samples have been made for 1 type of root barrier material, which become a total 42 specimens. Planted testing samples have been installed within the greenhouse, which will be observed regularly for 2 years from now on. We started test from July 11, 2008 and had performed intermediate observations every month for initial 3 months. From the 3rd intermediate observation on Sept. 18, we confirmed that 6 types of roe barrier materials have penetrated roots. Even though two types of them have been generally used as root barrier materials for roof planting system, all of three testing samples have a lot of penetrated roots. This result proves that it is not reasonable to introduce testing methods of root barrier from Europe. USA or Japan.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.13-24
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• 1993

The influence of the bubble structure and strength characteristics on the freeze-thaw resistance of high strength concrete is investigated by the laboratory experiment. The test conditions are formed in the manner that water is continueusly supplied externally and the specimens were received severe weather actions from ordinary to significantly low temperatures. The experiments are performed in two stages. In the first stage, the relation between the durability to frost action and the bubble structure is analyzed especially with respect to the water-cement ratio and the amount of air. The AE and non-AE concrete specimens made of ordinary portland cement are used in the test. In the second stage, the non-AE concrete specimens using vibratory compaction to improve the durability to frost action, and the high watertight specimens of rapid hardening portland cement to increase their initial strength are produced and tested. The degree of watertightness of the specimens is determined by measuring the permeability of the specimens and the bubble structure of the high watertight concrete is also estimated.

• Smart Structures and Systems
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• v.30 no.3
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• pp.327-332
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• 2022

In building envelope, transparent components play an important role. The structural glazing systems are the weak element of the casing in terms of mechanical resistance, thermal and acoustic insulation. In the present work, new structural glass panels with granular aerogel in interspace were investigated from different points of view. In particular, the mechanical characterization was carried out in order to assess the resistance to bending of the single glazing pane. To this end, a special instrument system was built to define an alternative configuration of the coaxial double ring test, able to predict the fracture strength of glass large samples (400 × 400 mm) without overpressure. The thermal and lighting performance of an innovative double-glazing façade with granular aerogel was evaluated. An experimental campaign at pilot scale was developed: it is composed of two boxes of about 1.60 × 2 m² and 2 m high together with an external weather station. The rooms, identical in terms of size, construction materials, and orientation, are equipped with a two-wing window in the south wall surface: the first one has a standard glazing solution (double glazing with air in interspace), the second room is equipped with the innovative double-glazing system with aerogel. The indoor mean air temperature and the surface temperature of the glass panes were monitored together with the illuminance data for the lighting characterization. Finally, a brief energy characterization of the performance of the material was carried out by means of dynamic simulation models when the proposed solution is applied to real case studies.

• Journal of Navigation and Port Research
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• v.33 no.3
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• pp.215-220
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• 2009

Container cranes are vulnerable structure to difficult weather conditions bemuse there is no shielding facility to protect them from strong wind. This study was carried out to analyze the effect of wind load on the structure of a container crane according to the change of the boom shape using wind tunnel test and computation fluid dynamics. And we provide a container crane designer with data which am be used in a wind resistance design of a container crane assuming that a wind load 75m/s wind velocity is applied in a container crane. In this study, we applied mean wind load conformed to 'Design Criteria of Wind Load' in 'Load Criteria of Building Structures' and an external fluid field was divided as interval of 10 degrees to analyze the effect according to a wind direction. In this conditions, we carried out the wind tunnel test and the computation fluid dynamic analysis and than we analyzed the wind load which was needed to design the container crane.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.261-272
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• 2001

An ACR/HMMM film was prepared by blending high-solid ACR with curing agent, hexamethoxymethyl melamine (HMMM). An active curing reaction was observed at $170^{\circ}C$. The dynamic viscoelastic $T_{g}$ of the final film increased with the static viscoelastic $T_{g}$ of the film. The log damp value, which means a viscoelastic ratio, decreased with the increase in the curing temperature of the film. Physical properties of the films were within a suitable range for films, and by an accelerated weathering resistance test the films were proved weather resistible ones.

• Steel and Composite Structures
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• v.2 no.1
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• pp.1-20
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• 2002

Fiber-Reinforced Plastics (FRP) have received significant attention for use in civil infrastructure due to their unique properties, such as the high strength-to-weight ratio and stiffness-to-weight ratio, corrosion and fatigue resistance, and tailorability. It is well known that FRP wraps increase the load-carrying capacity and the ductility of reinforced concrete columns. A number of researchers have explored their use for seismic components. The application of concern in the present research is on the use of FRP for corrosion protection of reinforced concrete columns, which is very important in cold-weather and coastal regions. More specifically, this work is intended to give practicing engineers with a more practical procedure for estimating the strength of a deficient column rehabilitated using FRP wrapped columns than those currently available. To achieve this goal, a stress-strain model for FRP wrapped concrete is proposed, which is subsequently used in the development of the moment-curvature relations for FRP wrapped reinforced concrete column sections. A comparison of the proposed stress-strain model to the test results shows good agreement. It has also been found that based on the moment-curvature relations, the balanced moment is no longer a critical moment in the interaction diagram. Besides, the enhancement in the loading capacity in terms of the interaction diagram due to the confinement provided by FRP wraps is also confirmed in this work.

• Current Photovoltaic Research
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• v.11 no.4
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• pp.108-113
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• 2023

Pressure to reduce costs in the current solar market is driving the development and implementation of new module designs and prompting the use of new materials and components. In order to utilize the variability of each material that makes up the module, it is essential to understand the basic characteristics of the material. In this article, we evaluate light degradation after UV irradiation as an encapsulation material. Measure and analyze the results of various characteristic tests for discoloration, optical and electrical property degradation before and after UV accelerated testing. To evaluate weathering stability, UV tests were performed comparing existing EVA and UVT-EVA, POE and improved low-cost POE. Even in the weather resistance test with a total UV exposure of 60 kW/m², the properties of the encapsulants were mostly stable. EVA and POE-based encapsulants showed slight differences, and these slight differences are believed to pose a threat to long-term stability. This study is a basic analysis of encapsulation research for PV modules and will be helpful in understanding future development and encapsulant properties.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.397-405
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• 2001

In clod weather regions, a strong seasonal wind brings sea salts to the land. In addition to it, recently, the spreading amount of deicing salts has increased numerously for purpose of removing snow and ice. Thus the salts environment around concrete structures becomes so severe that various damages of concrete due to applied salts will be brought up. Much of countries such as America, Europe etc. is carried out study for effects of deicing salts on concrete. However, there are not test methods for deterioration of concrete subjected to both freezing-thawing and chloride in Korea. In this study, we carried out test for the compound deterioration subjected to both freezing-thawing and chloride attack, to investigate the effects of sodium chloride on the deterioration of concrete. The test was performed to investigate the effects of cement type, strength and air content on the scaling deterioration of concrete. As a result, the scaling deterioration was accelerated in the presence of salts. And the resistance to scaling was strongly influenced by the type of cement, the strength and air content of concrete.

• Steel and Composite Structures
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• v.49 no.3
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• pp.337-348
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• 2023

Successive wetting and drying cycles of concrete due to weather changes can endanger the safety of engineering structures over time. Considering wetting and drying cycles in concrete tests can lead to a more correct and reliable design of engineering structures. This study aims to provide a model that can be used to estimate the resistance properties of concrete under different wetting and drying cycles. Complex sample preparation methods, the necessity for highly accurate and sensitive instruments, early sample failure, and brittle samples all contribute to the difficulty of measuring the strength of concrete in the laboratory. To address these problems, in this study, the potential ability of six machine learning techniques, including ANN, SVM, RF, KNN, XGBoost, and NB, to predict the concrete's tensile strength was investigated by applying 240 datasets obtained using the Brazilian test (80% for training and 20% for test). In conducting the test, the effect of additives such as glass and polypropylene, as well as the effect of wetting and drying cycles on the tensile strength of concrete, was investigated. Finally, the statistical analysis results revealed that the XGBoost model was the most robust one with R2 = 0.9155, mean absolute error (MAE) = 0.1080 Mpa, and variance accounted for (VAF) = 91.54% to predict the concrete tensile strength. This work's significance is that it allows civil engineers to accurately estimate the tensile strength of different types of concrete. In this way, the high time and cost required for the laboratory tests can be eliminated.

• Journal of the Korean GEO-environmental Society
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• v.17 no.5
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• pp.17-25
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• 2016

The rocks exposed on the surface undergo expedite weathering process due to the effects of climatic process, etc. and the weathering process changes the properties of minerals, thereby lowering the stability of rocks. Therefore, it is important to examine the composition of minerals in order to investigate the resistance of rocks against weathering, which is performed by weathering sensitivity analysis. And microscopic flaking test was performed for the bored samples in this study and the composition of minerals that are vulnerable to weathering was measured through mode analysis. The lithological and mineralogical weathering factors were evaluated through this process. Furthermore, the degree of progress of weathering was identified by quantitatively measuring the actual mineral composition of rocks through X-Ray diffraction analysis and identifying the secondary minerals through observation with a scanning electron microscope. This analyzing the weathering sensitivity was analyzed to be capable of determining appropriate indicators that can determine weather resistance and predicting the weathering grade using chemical weathering speed.