• 대한의용생체공학회:의공학회지
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• 제22권1호
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• pp.49-58
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• 2001

본 연구에서는 진자 실험을 통하여 중추신경계 질환인 경직을 정량적으로 판정할 수 있는 새로운 LCL(Logically Classified Level) 척도(scale)가 개발되었다. 새로운 척도개발에는 총 30개의 변수가 사용되었다. 이를 위하여 실험결과의 통계적 분석이 수행되었고 이들 중 진자 실험에서 경직의 특성이 가장 잘 반영되는 변수가 대표변수로 선정되었다. 사용된 30개의 변수 중 20개는 새로 도출된 변수이며 10개는 선행된 연구자들에 의하여 개발된 변수이다. 새로운 20개의 변수들은 진자 실험에서 발생되는 특성들인 각도, 각속도, 근육 모델, EMG가 고르게 반영될 수 있도록 이들의 조합으로 도출되었다. 이변량 상관분석결과 총 30개의 변수들 중 11개의 변수들은 서로 밀접한 상관성이 있음이 파악되었다. 11개의 서로 강한 상관성을 보이는 변수 중 논리적인 모순이 없는 L11이 대표변수로 선택되었다. 28명의 환자 데이터는 대표변수인 L11를 기준으로 4개의 그룹으로 분리되었고 최종으로 이들 그룹의 경향을 예측할 수 있는 회귀 방정식을 유도하였다. 새로운 척도에 사용된 대표변수인 L11은 환자들에게서 나타날 수 있는 여러 경우에 적합한지 검토되었는데 미소한 환자의 상태까지 잘 반영하고 있음이 드러났다. 따라서 새로운 LCL 척도는 기존의 준 정량적인 척도인 MAS(Modified Ashworth Scale)를 대체할 수 있을 것으로 기대된다. 특히 환자의 초기 진단뿐만 아니라 동일한 환자의 치료전후, 병적 호전에 대하여 정밀하게 파악할 수 있어 약물의 처방량 조절, 치료기간 등 치료의 전략에 사용될 수 있을 것으로 기대된다.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.573-585
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• 2018

This article presents strain gradient elasticity-based procedures for static bending, free vibration and buckling analyses of functionally graded rectangular micro-plates. The developed method allows consideration of smooth spatial variations of length scale parameters of strain gradient elasticity. Governing partial differential equations and boundary conditions are derived by following the variational approach and applying Hamilton's principle. Displacement field is expressed in a unified way to produce numerical results in accordance with Kirchhoff, Mindlin, and third order shear deformation theories. All material properties, including the length scale parameters, are assumed to be functions of the plate thickness coordinate in the derivations. Developed equations are solved numerically by means of differential quadrature method. Proposed procedures are verified through comparisons made to the results available in the literature for certain limiting cases. Further numerical results are provided to illustrate the effects of material and geometric parameters on bending, free vibrations, and buckling. The results generated by Kirchhoff and third order shear deformation theories are in very good agreement, whereas Mindlin plate theory slightly overestimates static deflection and underestimates natural frequency. A rise in the length scale parameter ratio, which identifies the degree of spatial variations, leads to a drop in dimensionless maximum deflection, and increases in dimensionless vibration frequency and buckling load. Size effect is shown to play a more significant role as the plate thickness becomes smaller compared to the length scale parameter. Numerical results indicate that consideration of length scale parameter variation is required for accurate modelling of graded rectangular micro-plates.

• 한국전문물리치료학회지
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• 제9권3호
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• pp.47-65
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• 2002

This study examined the correlations among the Berg Balance Scale, which is a clinical tool used to evaluate balance ability, spatiotemporal parameters of gait, and falling; determined the parameters most closely related to falling; and identified a discriminatory parameter and its predictability. Thirty-four subjects aged 72 to 92 years participated in this study. Following a questionnaire survey about falling, the Berg Balance Scale and spatiotemporal parameters of gait were measured. The results revealed that the incidence of falls increased with aging and an accompanying reduction in the flexion range of motion of the hip joint. The gait characteristics of elderly people who fell easily included a slower walking speed, shorter stride, and longer stance time than other elderly. When the cutoff score was set at 45, the Berg Balance Scale was able to identify correctly those individuals who truly have experience of falling than when the cutoff score was set at 39. But when the cutoff score was set at 39, the scale's specificity identifying correctly those individuals who truly have not experience of falling was higher than at the cutoff score of 45. Therefore, the Berg Balance Scale is an appropriate screening method in a clinical setting for the early detection of elderly people at risk of falling. In conclusion, elderly people with a Berg Balance Scale score. below 45 are the most likely to fall owing to their decreased balance ability.

• Journal of the Korean Data and Information Science Society
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• 제25권4호
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• pp.961-970
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• 2014

This article deals with the problem of testing the equality of the scale parameters of several inverted exponential distributions. We propose Bayesian hypothesis testing procedures for the equality of the scale parameters under the noninformative prior. The noninformative prior is usually improper which yields a calibration problem that makes the Bayes factor to be defined up to a multiplicative constant. So we propose the default Bayesian hypothesis testing procedures based on the fractional Bayes factor and the intrinsic Bayes factors under the reference priors. Simulation study and an example are provided.

• Journal of the Korean Data and Information Science Society
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• 제23권6호
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• pp.1299-1308
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• 2012

This article deals with the problem of testing the equality of the scale parameters in nonregular Pareto distributions.We propose Bayesian hypothesis testing procedures for the equality of the scale parameters under the noninformative prior. The noninformative prior is usually improper which yields a calibration problem that makes the Bayes factor to be de ned up to a multiplicative constant. So we propose the default Bayesia hypothesis testing procedures based on the fractional Bayes factor and the intrinsic Bayes factors under the reference priors. Simulation study and a real data example are provided.

• Journal of the Korean Data and Information Science Society
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• 제25권2호
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• pp.465-472
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• 2014

This article deals with the problem of testing the equality of the scale parameters in the half logistic distributions. We propose Bayesian hypothesis testing procedures for the equality of the scale parameters under the noninformative priors. The noninformative prior is usually improper which yields a calibration problem that makes the Bayes factor to be dened up to a multiplicative constant. Thus we propose the default Bayesian hypothesis testing procedures based on the fractional Bayes factor and the intrinsic Bayes factors under the reference priors. Simulation study and an example are provided.

• Journal of the Korean Data and Information Science Society
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• 제24권4호
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• pp.949-957
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• 2013

In this paper, we consider the problem of testing the equality of the scale parameters in two parameter exponential distributions. We propose Bayesian testing procedures for the equality of the scale parameters under the noninformative priors. The noninformative prior is usually improper which yields a calibration problem that makes the Bayes factor to be defined up to a multiplicative constant. Thus, we propose the default Bayesian testing procedures based on the fractional Bayes factor and the intrinsic Bayes factors under the reference priors. Simulation study and an example are provided.

• 응용통계연구
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• 제16권2호
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• pp.273-282
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• 2003

순서화된 척도모수들의 사전정보를 가지는 k-모집단 와이블분포의 모수추정을 위한 베이지안방법이 제시된다. 모수추정은 깁스샘플링에 의해서 이루어지며, 특히 깁스샘플러에서 형태모수의 조건부 사후분포는 로그-오목함수이므로 적응기각표집(Adaptive Rejection Sampling: ARS)방법에 의해 모수생성을 하였다. 논의된 모수추정법을 전기 절연유체 고장시간자료에 적용하여 척도모수의 순서화정보를 반영한 경우와 그렇지 않은 경우를 비교하였다.

• Journal of the Korean Statistical Society
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• 제17권2호
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• pp.61-80
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• 1988

For testing homogeneity of scale parameters aginst ordered alternatives, some nonparametric test statistics based on pairwise ranking method are proposed. The proposed tests are distribution-free. The asymptotic distributions of the proposed statistcs are also investigated. It is shown that the Pitman efficiencies of the proposed rank tests are the same as those of the corresponding two-sample rank tests in the scale problem. A small-sample Monte Carlo study is also performed. The results show that the proposed tests are robust and efficient.

• Advances in nano research
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• 제14권2호
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• pp.141-154
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• 2023

Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.