• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.943-948
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• 2003

The experimental study for oblong section was carried out by the column test in weak axis. The column specimens had 3 types of transverse steel configurations, such as interlocking spirals, interlocking circular hoop ties and rectangular ties. The oblong columns with interlocking spirals and with interlocking circular hoop ties showed better seismic performance than the rectangular columns with rectangular hoops and cross-ties. The objectives of this study were to provide experimental data on the behavior of interlocking spiral columns under cyclic loading, to compare the performance of columns with interlocking spirals to columns with various transverse steel configurations, to study the flexural detailing of interlocking spirals, interlocking circular hoops, and other transverse steel configurations as the transverse reinforcement, and to make recommendations for the design of bridge columns incorporating interlocking spirals, circular hoops as the transverse reinforcement.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.54-58
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• 2014

This study deals with the accidents of circular intersections in Korea. The goal is to develop the accident models for 94 circular intersections. In pursuing the above, this study gives particular attentions to collecting the data of geometric structure and accidents, and comparatively analyzing such the models as Poisson and NB regression and multiple regression model using SPSS 17.0 and LIMDEP 3.0. The main results are as follows. First, the negative binomial model among various models was analyzed to be the most appropriate. Second, 3 independent variables was adopted in the model, and these variables was analyzed to have a positive relation to the accident rate. Finally, the reduced width of circulatory roadway, removal of the parking lot within circulatory roadway and appropriate levels of approach lane were required to improve the safety of circular intersection.

• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.88-93
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• 2021

For a flow normal to a circular disk, the flow separation occurs from the edge of the disk and the flow recirculation zone exists behind the disk. Many existing studies conducted simulations of flow normal to a circular disk under low Reynolds numbers. Some studies performed LES or DES simulations under high Reynolds numbers. However, comparative study for different RANS models for high Reynolds numbers is very limited. This study presents numerical simulations of a flow normal to a circular disk using Realizable k-ε model and SST k-ω model. The recirculation bubble length and drag coefficient were compared with the experimental data. The SST k-ω model showed the excellent predictions for the recirculation bubble length and drag coefficient.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.77-83
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• 1997

This work is concerned with the algorithm of generating a new circular are interpolation. This research presents a new biarc curve fitting that is a circular interpolation method based on a triarc curve fitting. The triarc method, where a segment span is composed of three circular arcs, using maximum error estimation has the advantage of generating arc splines easily to a given tolerance. The new biarc method is called when the adjacent radii are the same in the same in the triarc method. In generating the machining data for various cam curves in CNC machining with the biarc method and the new biarc method, the latter accomp- lished faster NC-code generation, shorter NC-code block formation and machined the same cam profile more efficiently.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.584-589
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• 2001

The latch needle cam system of circular knitting machines is analysed using multibody dynamics. A formulation is made to obtain the vertical stiffness between the needle and the cam. By implementing this formulation into data of the multibody dynamics program, the motion and the force between the needle and the cam are obtained.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.9
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• pp.762-767
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• 2003

An experimental study was conducted to investigate the heat transfer characteristics of a circular finned-tube heat exchanger. The nineteen cases of configuration varying fin material, fin outer diameter and fin pitch were tested by means of the experiment and the numerical calculation. The measured heat transfer data for the circular finned-tube heat exchanger were provided. A transition of heat transfer was found in the case of low fin pitch. The thermal conductivity of fin affected on the pure heat transfer coefficient.

• The Journal of Korea Robotics Society
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• v.15 no.1
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• pp.62-69
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• 2020

This paper proposes a pattern recognition and classification algorithm based on a circular structure that can reflect the characteristics of the sEMG (surface electromyogram) signal measured in the arm without putting the placement limitation of electrodes. In order to recognize the same pattern at all times despite the electrode locations, the data acquisition of the circular structure is proposed so that all sEMG channels can be connected to one another. For the performance verification of the sEMG pattern recognition and classification using the developed algorithm, several experiments are conducted. First, although there are no differences in the sEMG signals themselves, the similar patterns are much better identified in the case of the circular structure algorithm than that of conventional linear ones. Second, a comparative analysis is shown with the supervised learning schemes such as MLP, CNN, and LSTM. In the results, the classification recognition accuracy of the circular structure is above 98% in all postures. It is much higher than the results obtained when the linear structure is used. The recognition difference between the circular and linear structures was the biggest with about 4% when the MLP network was used.

• Steel and Composite Structures
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• v.38 no.6
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• pp.739-749
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• 2021

This paper introduces an improved design equation to evaluate the resisting capacity of circular reinforced concrete (RC) columns partially strengthened with outer steel tube. When RC column members are required to be strengthened according to the change in the loadings considered and/or the deterioration progress in columns, wrapping up RC column with steel circular tube, which takes the form of concrete filled steel tube (CFST), has been popularly considered because of its structural advantage induced from the confinement effect. However, the relatively high construction cost of steel tube is restricting its use to the required region, while deriving the shape of a partial CFST column. To evaluate the resisting capacity of a partial CFST column, numerical analyses need to be performed, and a numerical model proposed in the previous study for the numerical analysis of full CFST columns is used to conduct parametric studies for the introduction of a design equation. The bond-slip effect developed along the interface between the in-filled concrete and the exterior steel tube is taken into consideration and the validity of the numerical model has been established through correlation studies between experimental data and numerical results for partial CFST circular columns. Moreover, parametric studies make it possible to introduce a design equation for determining the optimum length of outer steel tube which produces partial CFST circular columns.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.930-937
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• 2011

The characteristics of mean velocity and turbulence have been analyzed in the circular open channel flow using PIV measurement data for a wide range of water depth. The measured data are fitted to a velocity distribution function over the whole depth of the open channel. Reynolds shear stress and mean velocity in wall unit are compared with the analytic models for fully-developed turbulent boundary layer. Both the mean velocity and Reynolds shear stress have different distributions from the two-dimensional boundary layer flow when the water depth increases over 50% since the influence of the side wall penetrates more deeply into the free surface. The cross-stream Reynolds normal stress also has considerably different distribution in view of its peak value and decreasing rate in the outer region whether the water depth is higher than 50% or not.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.117-126
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• 1994

This paper describes an application step of a $R^{-{\theta}}$ method which measures circular movements in machining centers. The detection of composite errors of circular movements and a high precision cutting method in machining centers were investigated by the analysis of data measured by $R^{\theta }$method which can detect the rotating angle and is applicable to variable measuring radius. When the error by squareness error and unbalance of position-loop-gain were mixed, the detection method of each error was proposed. Although the errors by squarenss error and backlash compensation were mixed, the errors by squareness error be detected. If the errors by unbalance of position-loop-gain and backlash compensation were mixed, the errors by unbalance of position-loop-gain could not detected. A high precision cutting mehod, which uses the NC program compensated by using feed-back data from error measured by the $R^{\theta }$method, was proposed.