• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.67-70
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• 2005

In this study, an experimental investigation of the strength of R/C columns with 300mm square sections confined by head anchorage bar is presented. This initial phase of research considers only axial loading and consists of a total of 7 column tests. The main variables are distance and anchorage type of transverse reinforcement such as standard hooks and headed bar. The purpose of this study is to investigate the confinement effect and strength increment by head and to propose the confinement model for column using the head at end of lateral tie. Also, the test results for ultimate strength and strength gain factor of columns in this study and previous study is compared with the existing analytical models. Based on the test results, the Saatcioglu's model estimates confinement effects was closed to experimental value and the developed analytical approach considered the head was capable of predicting the strength gain factor results with a resonable accuracy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.83-84
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• 2017

In the construction site, it is necessary to estimate the compressive strength of concrete in order to adjust the demolding time of the form, and establish and adjust the construction schedule. The compressive strength of concrete is determined by various influencing factors. However, the conventional method for estimating the compressive strength of concrete has been suggested by considering only 1 to 3 specific influential factors as variables. In this study, seven influential factors (W/B ratio, Water, Cement, Fly ash, Blast furnace slag, Curing temperature, and humidity) of papers opened for 10 years were collected at three conferences in order to know the various correlations among data and the tendency of data. The purpose of this paper is to estimate compressive strength more accurately by applying it to algorithm of the Deep learning.

• Computers and Concrete
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• 제23권4호
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• pp.255-265
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• 2019

The potential of using genetic programming to predict engineering data has caught the attention of researchers in recent years. The present paper utilized weighted genetic programming (WGP), a derivative model of genetic programming (GP), to model the compressive strength of concrete. The calculation results of Abrams' laws, which are used as the design codes for calculating the compressive strength of concrete, were treated as the inputs for the genetic programming model. Therefore, knowledge of the Abrams' laws, which is not a factor of influence on common data-based learning approaches, was considered to be a potential factor affecting genetic programming models. Significant outcomes of this work include: 1) the employed design codes positively affected the prediction accuracy of modeling the compressive strength of concrete; 2) a new equation was suggested to replace the design code for predicting concrete strength; and 3) common data-based learning approaches were evolved into knowledge-based learning approaches using historical data and design codes.

• Journal of the Korean Geosynthetics Society
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• 제23권1호
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• pp.9-16
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• 2024

In order to evaluate the relationship between the ground confining pressure and the shear characteristics of the pile-soil interface, this study described the comparative results of the existing experimental results and the FEA results using the strength reduction factor. The strength reduction factor was applied to simulate the shear behavior of the pile-soil interface in finite element analysis(FEA). The analysis results showed that the maximum pullout resistance decreased due to the influence of low confining pressure, as the fines content increased. This trend was similar to the previous experimental research, and this FEA model simulated with the interface strength reduction factor was evaluated as reasonable. The analysis results of the variation in the interface strength reduction factor clearly showed that the interface strength reduction factor clearly increased at a high fines content when the confining pressure was 50kPa. However, it was found that the increase rate was low when the confining pressure was 100kPa and 150kPa. Therefore, confining pressure and fines content need to be considered in FEA to evaluate the shear behavior of the pile-soil interface.

• Architectural research
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• 제7권1호
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• pp.39-48
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• 2005

Main objective of this research is to evaluate performance of high-strength concrete (HSC) columns for ductility and strength. Eight one-third scale columns with compressive strength of 69 MPa were subjected to a constant axial load corresponding to 30 % of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement (${\rho}_s=1.58$, 2.25 %), tie configuration (Type H, Type C and Type D) and tie yield strength ($f_{yh}=549$ and 779 MPa). Test results show that the flexural strength of every column exceeds the calculated flexural capacity based on the equivalent concrete stress block used in the current design code. Columns with 42 % higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour, showing a displacement ductility factor (${\mu}_{{\Delta}u}$) of 3.69 to 4.85, and a curvature ductility factor (${\mu}_{{\varphi}u}$) of over 10.0. With an axial load of 30 % of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 549 MPa.

• Journal of the Earthquake Engineering Society of Korea
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• 제20권3호
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• pp.145-153
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• 2016

Small-size buildings are not designed by professional structural engineers in Korea. Therefore, their seismic performance can not be exactly estimated because their member sizes and reinforcement may be over- or under-designed. A prescriptive design criteria for the small-size buildings exists, but it also provides over-designed structural members since structural analysis is not incorporated, so it is necessary to revise the prescriptive criteria. The goal of this study was to provide an information for the revision, which is seismic performance and capability of small-size reinforced concrete moment frame buildings. For the study, the state of existing small-size reinforce-concrete buildings such as member size and reinforcement was identified by investigating their structural drawings. Then, over-strength, ductility and response modification factor of the small-size reinforced concrete moment frame buildings were estimated by analytical approach along with seismic performance check. The result showed that they possess moderate over-strength and ductility, and may use slightly increased response modification factor.

• Transactions on Electrical and Electronic Materials
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• 제1권4호
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• pp.25-29
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• 2000

In this paper, PET(Ployethylene Terephthalate) films with semiconducting and interface layers were investigated, The electrical properties, such as volume resistivity, tan$\delta$(dissipation factor) and breakdown strength at various temperatures were measured. Thermal analysis of PET and semiconducting films were measured and compared by differential scanning calorimeter(DSC) of each film. It is found that the volume resistivity of films(dependence on semiconducting interface layers)and electrical properties of PET films are changed ,Breakdown strength and dissipation factor of PET films with semiconducting layer (PET/S/PET) are decreased more greatly than PET and PET/PET films, due to the increase of charge density of charges at two contacted interfaces between PET and semiconductor, The dissipation factor of each films in increased with temperature,. For PET/S/PET film, is depended on temperature more than PET of PET/PET. However, the breakdown strength is increased up to 85$\^{C}$ and then decreased over 100$\^{C}$The electrical properties of PET films with semiconducting/interface layer are worse than without it It is due to a result of temperature dependency, which deeply affects thermal resistance property of PET film more than semiconducting/interface layers.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제33권2호
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• pp.483-493
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• 2013

The high strength materials have been more widely used in a large reinforced concrete structures. It is known that the use of high strength material in RC structures give the benefits of the mechanical and durable properties, but the ductility decreases with an increase in the strength of the materials. In the design of a reinforced concrete beam, both the flexural strength and ductility need to be considered. So, it is necessary to assess accurately the ductility of the beam with high strength materials in order to ensure the ductility requirement in design. In this study, the effects of the material strength on the flexural behavior and curvature ductility factor of reinforcement concrete beam sections with various reinforcement conditions have been evaluated and a newly prediction formula for curvature ductility factor of RC beam has been developed considering the stress of compression reinforcement at ultimate state. The proposed predictions for the curvature ductility factor which is applicable to both singly and doubly reinforced concrete beam are verified by comparisons with other prediction formulas and the proposed formula offers fairly accurate within 9% error and consistent predictions for curvature ductility factor of reinforced concrete beam.

• Journal of Fashion Business
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• 제21권5호
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• pp.78-90
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• 2017

This study investigates the effects of appearance management behaviors on job search efficacy among female college students. Based on previous studies on appearance management behaviors and job search efficacy, the questionnaire items were developed. For the study, we conducted a questionnaire survey among 312 students from women's university in Seoul. The statistical analyses were performed using SPSS 23. The results were as follows. First, three types of appearance management factors have been identified: 'fashion & hair,' 'skin care & plastic surgery,' and 'body shape'; the reliability and validity of these factors were proved. Second, the appearance management behavior of female college students found to have a partially significant effect on job search efficacy: fashion & hair factor had a positive effect on job search strength; fashion & hair factor and body shape factor had a positive effect on job search skills. While skin care & plastic surgery factor had a negative effect on job search strength and job search skill. Third, between academic years, there were differences in job search efficacy but not in appearance management behavior. By majors, there were differences among skin care & plastic surgery factor, body shape factor, and job search strength factor. These results suggest that to improve the job search efficacy, proper appearance management through fashion and hair, and body shape management is necessary. In addition, it suggests that it is important to improve the effectiveness of employment by establishing the appearance management strategy that matches the characteristics of each major.

• Journal of the Korean Society of Clothing and Textiles
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• 제6권1호
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• pp.17-26
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• 1982

This article aims to determine the interrelation among exfoliation strength, the repeated laundry number, the coefficient of friction and the cover factor about the fusible interlining produced by using different amount resin. The practicality of stiffness and warmth of the fusible interling were examined. The results are summarized as follows: 1) As a factor that affecting the exfoliation strength of fusible interlining, the coefficient of friction and the cover factor about the fusible interlining produced by using different amount resin. (2) Regardless of the weight of the resin, the exfoliation strength of fusible interlining declined gradually as the repeated laundry number increased. This tendency arises much more in the case of the filament yarn fabric than in that of the spun yarn fabric. The stability of the exfoliation strength was better, regardless of the increase of the repeated laundry number, when the weight of the weight of the resin was 10 g/$m^2$. (3) The spun yarn fabric, which has more fuzz than the filament yarn fabric, is more suitable for the fabric of fusible interlining. The smaller the cover factor difference between the face cloth and the interlining cloth, the stronger the exfoliation strength. (4) When the stability of the shape is a necessary factor in the consumption of the fusible interlining, a resin weight of 20 g/$m^2$ is the most suitable; however when stiffness and warmth are necessary factors, a resin weight of 10 g/$m^2$ is the most suitable.