• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.4
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• pp.43-50
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• 2018

The purpose of this study is to improve the seismic performance of RC framed buildings such as piloti buildings and school facilities. For this purpose, a half size RC frame specimen (SFD) was made and the inside of frame was reinforced with steel frame and S type strut steel damper. The experimental results are compared with those of the previous studies under the same conditions. The comparative specimens are non-reinforced specimen (BF) and damper reinforced specimen (AFD) that confined the column with an aramid sheet. As a result of comparing the maximum strength, stiffness degradation and energy dissipation capacity, SFD specimen was evaluated to be better than comparative specimens. According to the experimental results and FE analysis results, it was confirmed that the shear deformation was concentrated in the steel damper. And it was showed that cracks were concentrated at the upper and lower ends of the strut of the S type damper, and the final failure was observed at struts. From this, it was verified that the steel damper appropriately dissipates energy due to the lateral load.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.3-10
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• 2017

Climate change not only has various impacts such as human shoes, economics, the environment, industry, etc. but the damage caused by this is also increasing, it is expected that severe damage will not occur without efforts to respond to climate change ing. Therefore, as the impact of climate change like the extreme weather phenomenon is dailyized and its strength tends to become stronger, as much as the mitigation measures of climate change, as a comparative effort to reduce the negative impact of climate change, adaptation to climate change is necessary. Especially when the damage caused by climate change (intense heat, torrential rain, cold wave and heavy snow etc.) as an institution responsible for the provision of public services such as public institutions, the socio-economic spread to the nation and the people The effect is very large. We confirmed the level of response to climate change for the entire public institution, and selected climate change risk which is relatively important for specific facilities and business establishments of public institutions, climate change adaptation measures We will try to utilize it as basic material of establishment.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1619-1626
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• 2020

In this study, the physical properties of water-dispersible polyurethane resins synthesized with polyammonium phosphate and HMDI were studied by coating film samples and full-grain surfaces. Solvent resistance was found to be unchanged in all samples, and in terms of tensile strength, DPU-AP3 (1.887 kgf/㎟) containing the most ammonium polyphosphate showed the lowest physical properties. The elongation rate was measured as 54 8% in the sample containing a large amount of ammonium polyphosphate. Abrasion resistance was measured as 548 mg.loss of a sample containing a lot of ammonium polyphosphate, and it was confirmed that the physical properties of the blended resin of ammonium polyphosphate and water-dispersible polyurethane were changed.

• Smart Structures and Systems
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• v.29 no.2
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• pp.337-350
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• 2022

This paper focuses on predicting the post-heating mechanical properties of cementitious composites reinforced with multi-scale additives using the Artificial Neural Network (ANN) approach. A total of four different feed-forward ANN models are developed using 261 data sets collected from 18 published sources. The models are optimized using 12 input parameters selected based on a comprehensive literature review to predict the residual compressive strength, the residual flexural strengths, elastic modulus, and fracture energy of heat-damaged cementitious specimens. Furthermore, the ANN is employed to predict the impact of several variables including; the content of polypropylene (PP) microfibers and carbon nanotubes (CNTs) used in the concrete, mortar, or paste mix design, length of PP fibers, the average diameter of CNTs, and the average length of CNTs. The influence of the studied parameters is investigated at different heating levels ranged from 25℃ to 800℃. The results demonstrate that the developed ANN models have a strong potential for predicting the mechanical properties of the heated cementitious composites based on the mixing ingredients in addition to the heating conditions.

• Composites Research
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• v.35 no.5
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• pp.359-364
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• 2022

Polymers are inherently vulnerable to flame, which limits their application to various high-tech industries. In addition, environmental regulations restrict the use of halogen-based flame retardants which has best flame-retardant effect. There are inorganic flame retardants and phosphorous flame retardants as representative non-halogen-based flame retardants. However, high content of flame retardants is required to impart high flame retardancy of the polymers, and this leads to a decrease in mechanical properties. In this research, a new approach for inorganic flame retardant-based polymer composites with high mechanical properties and flame retardancy was suggested. Inorganic flame retardants called as magnesium oxysulfate whisker (MOSw) were used in this research. MOSw can extinguish fire by releasing water and non-combustible gases when exposed to flame. In addition, they have reinforcing effect when added into the polymer with its high aspect ratio. Expandable graphite (EG) was used as a flame-retardant supplement by helping to form a more dense char layer. Through this research, it is expected that it can be applied to various industries requiring flame retardancy such as automobile, and architecture by replacing halogen-based flame polymer composites.

• Journal of Korean Association for Spatial Structures
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• v.22 no.4
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• pp.89-98
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• 2022

The recent earthquake in Korea caused a lot of damage to reinforced concrete (RC) columns with non-seismic details. The nonlinear analysis enables predicting the hysteresis behavior of RC columns under earthquakes, but the analytical model used for the columns must be accurate and practical. This paper studied the nonlinear analysis models built into a commercial structural analysis program for the existing RC columns. The load-displacement relationships, maximum strength, initial stiffness, and energy dissipation predicted by the three analysis models were compared and analyzed. The results were similar to those tested in the order of the fiber, Pivot, and Takeda models, whereas the fiber model took the most time to build. For columns subjected to axial load, the Pivot model could predict the behavior at a similar level to that of the fiber model. Based on the above, it is expected that the Pivot model can be applied most practically for existing RC columns.

• Steel and Composite Structures
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• v.52 no.1
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• pp.57-76
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• 2024

The management of waste tire rubber has become a pressing environmental and health issue, requiring sustainable solutions to mitigate fire hazards and conserve natural resources. The performance of waste materials in structural components needs to be investigated to fabricate sustainable structures. This study aims to investigate the behavior of glass fiber reinforced polymer (GFRP) reinforced rubberized concrete (GRRC) compressive components under compressive loads. Nine GRRC circular compressive components, varying in longitudinal and transverse reinforcement ratios, were constructed. A 3D nonlinear finite element model (FEM) was proposed by means of the ABAQUS software to simulate the behavior of the GRRC compressive components. A comprehensive parametric analysis was conducted to assess the impact of different parameters on the performance of GRRC compressive components. The experimental findings demonstrated that reducing the spacing of GFRP stirrups enhanced the ductility of GRRC compressive components, while the addition of rubberized concrete further improved their ductility. Failure in GRRC compressive components occurred in a compressive columnar manner, characterized by vertical cracks and increased deformability. The finite element simulations closely matched the experimental results. The proposed empirical model, based on 600 test samples and considering the lateral confinement effect of FRP stirrups, demonstrated higher accuracy (R² = 0.835, MSE = 171.296, MAE = 203.549, RMSE = 195.438) than previous models.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.41-50
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• 2000

Cement-bonded particleboard is being used as outdoor siding material all over the world, because this composite particularly bears a light weight, high resistance against fire, decay, and crack by cyclic freezing and thawing, anti-shock property, and strength enhancement. Construction systems are currently changing into a frame-building style and wooden houses are being constructed with prefabrication type. Therefore, they require a more durability at outdoor-exposed sides. In this study, the cement hydration property for Korean pine particle, Japanese larch particle and face- and middle layer particles (designated as PB particle below) used in Korean particleboard-manufacturing company was investigated, and the rapid manufacturing characteristics of cement-bonded particleboard by supercritical $CO_2$ curing was evaluated. Korean pine flour showed a good hydration property, however, larch flour showed a bad one. PB particle had a better hydration property than larch flour. The addition of $Na_2SiO_3$ indicated a negative effect on hydration, however, $MgCl_2$ had a positive one. Curing by supercritical $CO_2$ fluid gave a conspicuous enhancement in the performances of cement-bonded particleboards compared to conventional curing. $MgCl_2$ 3%-added PB particle had the highest properties, and $MgCl_2$ 1%-added Korean pine particle had the second class with the conditions of cement/wood ratio of 2.7, a small fraction-screened particle and supercritical curing. On the contrary, the composition of non-hammermilled or large fraction-screened particle at cement/wood ratio of 2.2 was poorer. Also, the feasibility for actual use of 3%-added, small PB particle-screened fraction was greatest of all the conventional curing treatments. Relative superiority of supercritical curing vs. conventional curing at dimensional stability was not so apparent as in strength properties. Through the thermogravimetric analysis, it was ascertained that the peak of a component $CaCO_3$ was highest, and the two weak peaks of calcium silicate hydrate and ettringite and $Ca(OH)_2$ were present in supercritical treatment. Accordingly, it was inferred that the increased formation of carbonates in board contributes to strength enhancement.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.986-993
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• 2021

This study was aimed to investigate the improvement effects of kelp extract on the damaged hair by manufacturing hair quality improving formulation adding kelp extract and applying that in the damaged hair. With respect to the study materials, the formulation was manufactured with different strengths of kelp extract including 0, 2, 4, and 6 grams, adding perm base material. The manufactured formulation was applied to the decolored sample hair of Level 8 and its effects were measured and compared before and after its application. Tensile strength, absorbance using methylene blue, and gloss were measured as the tools to show the improvement effects of hair quality. To check the reliability of the results, statistical analysis was performed. Tensile strength showed to be increased in the Level 8 samples applied by the formulations containing 4- and 6-gram strength. Absorbance using methylene blue showed to be decreased in all the samples after the application, based on the absorbance results before and after the application. No difference was found in all the samples on the gloss. In conclusion, this study revealed that kelp extract could improve the damaged hair. Further studies are required to check the improvement effects on the damaged hair with multiple types of extracts and study methods.

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.289-297
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• 2019

Epoxy resin adhesives are currently used as adhesives in buildings. Epoxy resin adhesives, which are organic materials, generate harmful substances when producing adhesives, and toxic substances are high in the residential space after installation. In addition, a large amount of carbon monoxide generated from organic materials in the case of a building fire leads to personal injury. This study evaluates the feasibility of inorganic adhesives using pure inorganic materials such as magnesia, phosphate, and borax as inorganic adhesives to replace existing organic adhesives. As a result of the experiment on the selection of adequate phosphate and the characteristics of the addition rate of borax used as a retarder, the potassium phosphate monobasic was obtained as a suitable phosphate and the characteristics according to the borax addition rate were compared with the quality standard of KS F 4923 The hardening shrinkage and heat change rate satisfied the quality standards. The tensile strength was satisfactory when the borax addition rate was 4% or more, but the adhesive strength did not meet the quality standards. Further studies are needed to improve adhesion strength.