• 응용통계연구
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• 제22권1호
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• pp.205-220
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• 2009

For modeling skewed semicircular data, we derive new family of the exponential distributions. We extend it to the l-axial exponential distribution by a transformation for modeling any arc of arbitrary length. It is straightforward to generate samples from the f-axial exponential distribution. Asymptotic result reveals two things. The first is that linear exponential distribution can be used to approximate the l-axial exponential distribution. The second is that the l-axial exponential distribution has the asymptotic memoryless property though it doesn't have strict memoryless property. Some trigonometric moments are also derived in closed forms. Maximum likelihood estimation is adopted to estimate model parameters. Some hypotheses tests and confidence intervals are also developed. The Kolmogorov-Smirnov test is adopted for goodness of fit test of the l-axial exponential distribution. We finally obtain a bivariate version of two kinds of the l-axial exponential distributions.

• Communications for Statistical Applications and Methods
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• 제15권5호
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• pp.775-781
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• 2008

It is developed that a family of the semicircular Laplace distributions for modeling semicircular data by simple projection method. Mathematically it is simple to simulate observations from a semicircular Laplace distribution. We extend it to the l-axial Laplace distribution by a simple transformation for modeling any arc of arbitrary length. Similarly we develop the l-axial log-Laplace distribution based on the log-Laplace distribution. A bivariate version of l-axial Laplace distribution is also developed.

• 응용통계연구
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• 제23권6호
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• pp.1125-1145
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• 2010

For modeling(skewed) semicircular data, we derive a new exponential family of distributions. We extend it to the l-axial exponential family of distributions by a projection for modeling any arc of arbitrary length. It is straightforward to generate samples from the l-axial exponential family of distributions. Asymptotic result reveals that the linear exponential family of distributions can be used to approximate the l-axial exponential family of distributions. Some trigonometric moments are also derived in closed forms. The maximum likelihood estimation is adopted to estimate model parameters. Some hypotheses tests and confidence intervals are also developed. The Kolmogorov-Smirnov test is adopted for a goodness of t test of the l-axial exponential family of distributions. Samples of orientations are used to demonstrate the proposed model.

• 응용통계연구
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• 제22권4호
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• pp.879-891
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• 2009

We developed the projected l-axial skew-normal(LASN) family of distributions for I-axial data. The LASN family of distributions contains the semicircular skew-normal(SCSN) and the circular skew-normal(CSN) families of distributions as special cases. The LASN densities are similar to the wrapped skew-normal densities for the small values of the scale parameter. However CSN densities have more heavy tails than those of the wrapped skew-normal densities on the circle. Furthermore the CSN densities have two modes as the scale parameter increases. The LASN distribution has very convenient mathematical features. We extend the LASN family of distributions to a bivariate case.

• Communications for Statistical Applications and Methods
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• 제15권5호
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• pp.667-674
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• 2008

We develop new family of the t distributions for modeling semicircular data. It has convenient mathematical features. It is extended to the l-axial t distribution and a generalized semicircular t distribution.

• 한국지반공학회논문집
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• 제35권12호
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• pp.25-33
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• 2019

본 연구에서는 수직증축 구조물의 기존말뚝의 축강성(K_ve)을 이론적인 접근과 현장 계측 결과를 바탕으로 추정하였다. 이론적인 접근에는 Randolph와 Wroth(1978)가 제안한 축강성 공식을 적용하여, 지중에 설치된 강성 및 연성말뚝의 세장비(L/D)에 따른 축강성의 범위를 도출하였다. 여기에, 1995 - 1997년 사이에 설치된 38본 말뚝의 계측된 시공 당시 축강성을 이론적으로 도출한 축강성 범위에 중첩해서 고려하였다. 이를 통하여, 노후화와 열화에 의하여 감소한 기존말뚝의 축강성의 최대값을 세장비에 따라 제안하였고, 도출된 값을 통계적인 기법을 통하여 상위 95% 값을 제안하여 신설 보강말뚝 설계 시 필요한 최소 축강성(K_vr)을 산정하는 데에 활용할 수 있도록 하였다.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.111-135
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• 2013

An experimental study has been carried out on square plain concrete (PC) and reinforced concrete (RC) columns strengthened with carbon fiber-reinforced polymer (CFRP) sheets. A total of 78 specimens were loaded to failure in axial compression and investigated in both axial and transverse directions. Slenderness of the columns, number of wrap layers and concrete strength were the test parameters. Compressive stress, axial and hoop strains were recorded to evaluate the stress-strain relationship, ultimate strength and ductility of the specimens. Results clearly demonstrate that composite wrapping can enhance the structural performance of square columns in terms of both maximum strength and ductility. On the basis of the effective lateral confining pressure of composite jacket and the effective FRP strain coefficient, new peak stress equations were proposed to predict the axial strength and corresponding strain of FRP-confined square concrete columns. This model incorporates the effect of the effective circumferential FRP failure strain and the effect of the effective lateral confining pressure. The results show that the predictions of the model agree well with the test data.

• 동력기계공학회지
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• 제10권4호
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• pp.38-42
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• 2006

Pressure drops and friction factors in square channels with twisted tape inserts plus axial interrupted ribs are investigated. Tests are performed for Reynolds numbers ranging from 8,900 to 29,000. The rib height-to-channel hydraulic diameter, $e/D_h$, is kept at 0.057 and test section length-to-hydraulic diameter, $L/D_h$ is 30. The pressure drops and friction factor values are enhanced with axial interrupted ribs and twisted tape inserts. Square channels with twisted tape inserts plus axial interrupted ribs show the greatest pressure loss penalty in the present work. Friction factor data obtained for the square channel with twisted tape inserts plus axial interrupted ribs are less than those in the past publications for circular tubes with axial interrupted ribs and twisted tape inserts.

• International Journal of CAD/CAM
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• 제9권1호
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• pp.121-128
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• 2010

The purpose of this study is to clarify the mechanical behavior of human lumbar vertebrae (L3/L4) with and without fusion bone under physiological axial compression. The author has developed the program code to build the patient specific three-dimensional geometric model from the computed tomography (CT) images. The developed three-dimensional model provides the necessary information to the physicians and surgeons to visually interact with the model and if needed, plan the way of surgery in advance. The processed data of the model is versatile and compatible with the commercial computer aided design (CAD), finite element analysis (FEA) software and rapid prototyping technology. The actual physical model is manufactured using rapid prototyping technique to confirm the executable competence of the processed data from the developed program code. The patient specific model of L3/L4 vertebrae is analyzed under compressive loading condition by the FEA approach. By varying the spacer position and fusion bone with and without pedicle instrumentation, simulations were carried out to find the increasing axial stiffness so as to ensure the success of fusion technique. The finding was helpful in positioning the fusion bone graft and to predict the mechanical stress and deformation of body organ indicating the critical section.

• Steel and Composite Structures
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• 제21권2호
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• pp.323-342
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• 2016

To study the effect of collar-plate reinforcement on the static strength of tubular T-joints under axial loading, fundamental research work is carried out from both experimental test and finite element (FE) simulation. Through experimental tests on 7 collar-plate reinforced and 7 corresponding un-reinforced tubular T-joints under axial loading, the reinforcing efficiency is investigated. Thereafter, the static strengths of the above 14 models are analyzed by using FE method, and it is found that the numerical results agree reasonably well with the experimental data to prove the accuracy of the presented FE model. Additionally, a parametric study is conducted to analyze the effect of some geometrical parameters, i.e., the brace-to-chord diameter ratio ${\beta}$, the chord diameter-to-chord wall thickness ratio $2{\gamma}$, collar-plate thickness to chord wall thickness ratio ${\tau}_c$, and collar-plate length to brace diameter ratio $l_c/d_1$, on the static strength of a tubular T-joint. The parametric study shows that the static strength can be greatly improved by increasing the collar-plate thickness to chord wall thickness ratio ${\tau}_c$ and the collar-plate length to brace diameter ratio $l_c/d_1$. Based on the numerical results, parametric equations are obtained from curving fitting technique to estimate the static strength of a tubular T-joint with collar-plate reinforcement under axial loading, and the accuracy of these equations is also evaluated from error analysis.