• Communications for Statistical Applications and Methods
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• 제19권4호
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• pp.527-536
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• 2012

In this paper we analyze the effect of circular variables such as wind direction, time and month on the ozone level. In particular, we examined the effect of wind direction by exploratory data analysis methods and provide the correlation and regression analyzes in the cases including all circular explanatory variables. In the analysis, we convert time and month variables to circular variables and analyze the effect of these variables on regression analysis; in addition, we also consider circular-circular regression. We used weather condition and air pollution data collected from Dongdaemoon district of Seoul in 2007.

• Journal of the Korean Data and Information Science Society
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• 제22권5호
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• pp.961-966
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• 2011

Circular variables are those that have a period in its range. Their examples include direction of animal migration, and time of drug administration, just to mention a few. Statistical analysis of circular variables is quite different from that of linear variable due to its periodic nature. In this paper, the author proposes new circular regression models using geodesic lines on the surface of the sample space of the response and the predictor variables.

• 한국항공운항학회지
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• 제30권4호
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• pp.184-190
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• 2022

In an attempt to apply hybrid rocket to the RATO (Rocket-Assisted Take Off) system, combustion characteristics of the non-circular grain were figured out in this study. Having larger combustion area, it was reconfirmed that the non-circular grain has advantages over regression rate, characteristic velocity and chamber pressure in which all gave higher values. Experiments were performed to understand the effect of the non-circular grain geometry over time where local regression rates depending on grain location were analyzed. It was found that the regression rate of five distinct locations were different. Partial conclusion driven was that these differences are due to the heat transfer caused by dissimilar distances from the flame layer. Besides, as combustion duration increased, the fuel port became circular, and the regression rate converged to a single value over the whole grain.

• 한국안전학회지
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• 제29권1호
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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.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.227-234
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• 2003

This study presents the stress evaluation equations of circular column-box beam connection in steel frame piers. FEM analysis were carried out for circular column-box beam connection. Analysis models were made for design parameters such as joint angle, span length-width ratio(L/B), sectional-area ratio(S=A/sub w/A/sub f/), and circular column-box beam stiffness ratio(Ic/Ib). Analysis results were compared to the existing equation. Based on analysis results the stress evaluation equations of circular column-box beam connection are proposed by regression analysis.

• 소성∙가공
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• 제11권5호
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• pp.394-404
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• 2002

The drawbead model for a three-dimensional a finite element analysis of sheet metal forming processes is developed. The mathematical models of the basic drawbeads like circular drawbead, stepped drawbead, and squared drawbaed are first derived using the bending theory, belt-pulley equation, and Coulomb friction law. Next, the experiments for finding the drawing characteristics of the drawbead are performed. Based on mathematical models and drawing test results, expert models of basic drawbeads are then developed employing a linear multiple regression method. For the expert models of combined drawbeads such as the double circular drawbead, double stepped drawbead, circular-and-stepped drawbead, etc., those of the basic drawbeads are summed. Finally, in order to verify the expert models developed, the drawing characteristics calculated by the expert models of the double circular drawbead and circular-and-stepped drawbead are compared with those obtained from the experiments. The predictions by expert models agree well with the measurements by experiments.

• 한국안전학회지
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• 제27권6호
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• pp.178-184
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• 2012

This study deals with the traffic accidents by weather condition. The objectives are to comparatively analyze the characteristics, and to develop the models of traffic accidents by weather condition. In pursuing the above, this paper gives particular attentions to testing the differences between two groups, and developing the models(Poisson and negative binomial regression) using the data of domestic circular intersections. The main results are as follows. First, three Poisson models and one negative binomial models which were all statistically significant were developed using the number of accident and EPDO by the clear weather and other as the dependant variables. Second, the differences between two models were comparatively analyzed using the chosen variables. This paper might be expected to give some implications to traffic safety policy-making to reduce and prevent the traffic accidents in circular intersections.

• 한국안전학회지
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• 제32권5호
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• pp.129-134
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• 2017

This study aims to develop the traffic accident models by circular intersection type using count data model. The number of accident, the number of fatal and injured persons(FSI), and EPDO are calculated from the traffic accident data of TAAS. The circular intersection accident models are developed through Poisson and negative binomial regression analysis. The main results of this study are as follows. First, the null hypotheses that there are differences in the number of traffic accidents, FSI and EPDO by type of circular intersections are rejected. Second, the scale of intersection(median, large), number of approach road, mean width and length of exit road, area of the circulating roadway and central island are selected as factors influencing the number of traffic accidents, FSI and EPDO in rotary. Third, the scale of intersection(median), guide signs(limited speed, direction, roundabout), number of approach road, entry angle, area of the intersection and central island are adopted as factors influencing the number of traffic accidents, FSI and EPDO in roundabout. Finally, transferring from rotary to roundabout could be expected to make the accident decrease.

• Steel and Composite Structures
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• 제33권5호
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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.

• 한국도로학회논문집
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• 제19권5호
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• pp.143-151
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• 2017

PURPOSES : The purpose of this study is to develop models of accidents occurring at circular intersections related to the time of day and night and driver gender, and to provide countermeasures for safer circular intersections. METHODS : Seventy intersections built before 2008 were surveyed for inclusion in the modeling. Traffic accident data from 2008 to 2014 were collected from the TAAS data set of the Road Traffic Authority. Sixteen variables explaining the accidents including geometry and traffic volume were selected from the literature and seven multiple linear regression models were developed using SPSS 20.0. RESULTS : First, the null hypotheses, that the number of traffic accidents are not related to driver gender or time of day, were rejected at a 5% level of significance. Second, seven statistically significant accident models with $R^2$ value of 0.643-0.890 were developed. Third, in daytime models by gender, when the right-turn-only lane was selected as the common variable, the number of lanes, presence of driveways and speed humps, diagrammatic exit destination sign, and total entering traffic volume were evaluated as specific variables. Finally, in nighttime models by gender, when the diagrammatic exit destination sign was selected as the common variable, total entering traffic volume, presence of right-turn-only lanes, number of circulatory road way lanes, and presence of splitter islands and driveways were identified as specific variables. CONCLUSIONS:This study developed seven accident models and analyzed the common and specific variables by time of day and gender. The results suggest approaches to providing countermeasures for safer circular intersections.