• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.13-25
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• 2012

The purpose of this study was to investigate the seismic behavior of hollow circular reinforced concrete bridge columns with confinement steel, and to develop improved seismic design criteria. Three hollow circular columns were tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. The numerical method used gives a realistic prediction of the seismic performance throughout the loading cycles for the several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve current practice in the design and construction of hollow circular reinforced concrete bridge columns.

• International Journal of Fluid Machinery and Systems
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• v.10 no.1
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• pp.63-75
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• 2017

Many axial fans have circular arc blades with constant thickness. It is still a challenging task to calculate their performance, i.e. to predict how large their pressure rise and pressure losses are. For this task a need for cascade data exists. Therefore, the designer needs a method which works quickly for design purposes. In the present contribution a design method for such cascades consisting of circular arc blades with constant thickness is described. It is based on a singularity method which is combined with a CFD-data-based flow loss model. The flow loss model uses CFD-data to predict the total pressure losses. An interpolation method for the CFD-data are applied and described in detail. Data of measurements are used to validate the CFD-data and parameter variations are conducted. The parameter variations include the variation of the camber angle, pitch chord ratio and the Reynolds number. Additionally, flow patterns of two dimensional cascades consisting of circular arc blades with constant thickness are shown.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.32-38
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• 2014

In this paper, we design a secant pattern antenna combined with a septum circular polarizer to be used in the satellite data communications. To generate a radiation pattern with secant type, Fourier relationship between current distribution and space factor is applied and the circular symmetric structure of the aperture simplifies the design. The optimization process is performed by combining the radiator with the septum circular polarizer, and it is confirmed that the designed radiation pattern, axial ratio, and return loss characteristics satisfies the required performance of the antenna.

• Steel and Composite Structures
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• v.33 no.5
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• pp.681-697
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• 2019

This paper numerically assesses the initial stiffness and moment capacity of stainless steel composite bolted joints with concrete-filled circular tubular (CFCT) columns. By comparing with existing design codes including EN 1993-1-8 and AS/NZS 2327, a modified component method was proposed to better predict the flexural performance of joints involving circular columns and curved endplates. The modification was verified with independent experimental results. A wide range of finite element models were then developed to investigate the elastic deformations of column face in bending which contribute to the corresponding stiffness coefficient. A new design formula defining the stiffness coefficient of circular column face in bending was proposed through regression analysis. Results suggest that a factor for the stiffness coefficient of endplate in bending should be reduced to 0.68, and more contribution of prying forces needs to be considered. The modified component method and proposed formula are able to estimate the structural behaviour with reasonable accuracy. They are expected to be incorporated into the current design provisions as supplementary for beam-to-CFCT column joints.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.119-126
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• 2006

Gerotor hydraulic motor is widely used in hydraulic systems due to its low speed, high torque output and compactness in rotational direct driving of a heavy weight. Gerotor is a Planar mechanism consisted of a pair of rotor and circular teeth of stator assembly which forms a closed space, so called a chamber. The motion of rotor relative to the circular tooth is produced by the pressure difference of hydraulic operating fluid between the adjacent chamber. As all active contact points of rotor and circular teeth are subjected to very high sliding friction, a reduction in the performance of the gerotor hydraulic motor can not be avoided. Therefore, the core design parameters of gerotor profile used in hydraulic motors is to minimize a friction force by high contact stresses. The analytical design method of gerotor profile, based on envelope of a family of curves, is proposed. In this study, the influence of the tip clearances on three critical contact points between rotor and circular teeth of stator assembly has been explored by experimental data in this paper. At the same time a improvement method to reduce the friction force is proposed and the tip clearances on three critical points for getting an optimum gerotor profile are also analyzed.

• Steel and Composite Structures
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• v.47 no.5
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• pp.645-661
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• 2023

Concrete-filled steel tubular columns with double inner steel tubes (CFST-DIST) are a novel type of composite members developed from conventional concrete-filled steel tubular (CFST) columns. This paper investigates the structural performance of circular CFST-DIST stub columns using nonlinear finite element (FE) analysis. A numerical model was developed and verified against existing experimental test results. The validated model was then used to compare circular CFST-DIST stub columns' behavior with their concrete-filled double skin steel tubular (CFDST) and CFST counterparts. A parametric study was performed to ascertain the effects of geometric and material properties on the axial performance of CFST-DISTs. The FE results and the available test data were used to assess the accuracy of the European and American design regulations in predicting the axial compressive capacity of circular CFST-DIST stub columns. Finally, a new design model was recommended for estimating the compressive capacity of CFST-DISTs. Results clarified that circular CFST-DIST columns had the advantages of their CFST counterparts but with better ductility and strength-to-weight ratio. Besides, the investigated design codes led to conservative predictions of the compressive capacity of circular CFST-DIST columns.

• Journal of Digital Policy
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• v.2 no.1
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• pp.21-30
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• 2023

Current research and practice have increasingly sought to focus on approaches to facilitate innovation due to its expanding growth of the experience economy over the past decade. Normally, customer experience design aims to maximize the effectiveness of positive experience with a brand or company's touchpoints when customers make a purchase as well as use a certain product or service. In order to design a product or service that can provide varying levels of experiences, there needs more beneficial design process strategies to help resolve the changing nature of customer experience. Design process is one such approach that provides designers as well as researchers across various academic disciplines as an integral source of creativity, driving innovation and growth. In this regard, this study aims to look specifically at the nature of customer experience and attempts to understand what extent that design process in both practice and theoretical perspective can assist in customer experience improvement. As a further consequence, this study will focus on implementing the idea of circular design into the customer experience process, namely the Circular CX Design Process-which is expected to increase effectiveness and efficiency in addressing customer needs and demands as well as delivering positive experiences at various touchpoints along the customer journey.

• Education of Primary School Mathematics
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• v.15 no.1
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• pp.31-40
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• 2012

In this paper, we developed teaching learning models using a numeral operation for the mathematical gifted focused on the design of a circle using GSP and investigated effects of this models. This model gave gifted-students to be able to produce creative outputs with mathematical principles and practicality and beauty of mathematics. We found following facts. Firstly, a developed teaching-learning model improves a mathematical gifted student's mathematical creativity as analytic thinking and deductive inference. Secondly, a circular design using GSP helps gifted students to understand the abstract rules because mathematical patterns was represented visually by a circular design. Lastly, a circular design using a numeral operation is helpful to gifted students revealing to creativity and beauty of mathematics.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.2
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• pp.35-42
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• 2011

The seismic design of solid reinforced concrete bridge columns has been committed to, based on accumulated research and design specifications. The rational confinement model and seismic performance evaluation, however, are insufficient because of the lack of domestic and foreign design specifications about the experimental and analytical difficulties in the case of circular hollow reinforced concrete columns. In this paper, the seismic behavior of circular hollow reinforced concrete columns and its dependence on design variables are understood and explained. These research results can be used to derive the rational and economical design specifications for circular hollow sectional columns based on the result from the nonlinear analysis program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology).

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.5
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• pp.844-854
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• 2016

In order to understand the current state of production and pattern design of circular knitted jackets, this study selected 11 female clothing brands based from the "2012/2013 Korea Fashion Brand Yearbook" and interviewed the staff in charge of patterns at the companies. Polyester and polyurethane were found to be synthesized and used for the outshell of circular knitted jackets, alternatively natural fabric cotton or wool were synthesized with rayon. As for the structure of circular knitted materials, Ponte Di Roma knitting structure (a modified form of a double knit) was most often used. Surveying the use pattern and the parts for padding cloth, six responded that they used elastic padding cloth. As for circular knitted jackets with inner lining, elastic padding cloth was attached to all parts (front, back, side panel, and collar - except for sleeves) of the basic bodice pattern. Eight responded that they did not use a basic pattern when designing a pattern, which exceeds the majority. All respondents answered yes to the question on if there is any difference in designing a pattern for a woven jacket and a circular knitted jacket. It was found that they designed a pattern that considered shrinkage and elongation, which are the features of circular knitted fabric. Shrinkage and elongation were the features of a fabric material most considered when designing patterns for a circular knitted jacket.