• Smart Structures and Systems
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• 제19권1호
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• pp.21-31
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• 2017

To control the stochastic vibration of a vibration-sensitive instrument supported on a beam, the beam is designed as a sandwich structure with magneto-rheological visco-elastomer (MRVE) core. The MRVE has dynamic properties such as stiffness and damping adjustable by applied magnetic fields. To achieve better vibration control effectiveness, the optimal bounded parametric control for the MRVE sandwich beam with supported mass under stochastic and deterministic support motion excitations is proposed, and the stochastic and shock vibration suppression capability of the optimally controlled beam with multi-mode coupling is studied. The dynamic behavior of MRVE core is described by the visco-elastic Kelvin-Voigt model with a controllable parameter dependent on applied magnetic fields, and the parameter is considered as an active bounded control. The partial differential equations for horizontal and vertical coupling motions of the sandwich beam are obtained and converted into the multi-mode coupling vibration equations with the bounded nonlinear parametric control according to the Galerkin method. The vibration equations and corresponding performance index construct the optimal bounded parametric control problem. Then the dynamical programming equation for the control problem is derived based on the dynamical programming principle. The optimal bounded parametric control law is obtained by solving the programming equation with the bounded control constraint. The controlled vibration responses of the MRVE sandwich beam under stochastic and shock excitations are obtained by substituting the optimal bounded control into the vibration equations and solving them. The further remarkable vibration suppression capability of the optimal bounded control compared with the passive control and the influence of the control parameters on the stochastic vibration suppression effectiveness are illustrated with numerical results. The proposed optimal bounded parametric control strategy is applicable to smart visco-elastic composite structures under deterministic and stochastic excitations for improving vibration control effectiveness.

• Journal of the Korean Statistical Society
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• 제26권1호
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• pp.1-22
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• 1997

In the linear regression model $y_{i}$ = .alpha. $x_{i}$ $^{T}$ .beta. + .epsilon.$_{i}$ , i = 1,2,...,n, the weighted pairwise absolute deviation (WPAD) estimator was defined by minimizing the dispersion function D (.beta.) = .sum..sum.$_{{i $w_{{ij}}$$\mid$ $r_{j}$ (.beta.) $r_{i}$ (.beta.)$\mid$, where $r_{i}$ (.beta.)'s are residuals and $w_{{ij}}$'s are weights. This estimator can achive bounded total influence with positive breakdown by choice of weights $w_{{ij}}$. In this paper, we consider a more general type of dispersion function than that of D(.beta.) and propose a pairwise GM-estimator based on the dispersion function. Under some regularity conditions, the proposed estimator has a bounded influence function, a high breakdown point, and asymptotically a normal distribution. Results of a small-sample Monte Carlo study are also presented. presented.

• 보건행정학회지
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• 제5권2호
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• pp.18-34
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• 1995

To clarify the relationship between the medical supply(medical persons and goods) and the use of bed, the author has made comparison among OECD 24 countries. Per Capita Bed-days can be divided into Average Length of Stay and Admission Rate, and these three variables were regressed upon both In-patient Care Beds of all medical institutions including acute somatic, psychiatric, special, nursing homes and other long-term care and Share of Total Health Employment in Total Employment. The result of regression analysis shows a statistically significant positive relationship between In-patient Care Beds and Average Length of Stay, and negative relationship between Share of Total Health Employment and Admission Rate. In addition to Ordinary Least Square(OLS) estimation, amended Bounded Influence Estimation(BIE) was also made to adjust the influence of outliers. Japan shows a very large number of In-patient Care Beds and a very low Share of Total Health Employment, and this medical situation is judged to have close relation to her long Average Length of Stay and low Admission Rate.

• Communications for Statistical Applications and Methods
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• 제12권1호
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• pp.169-179
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• 2005

In this study, we investigate the effects of the weight function in the bounded influence regression quantile (BIRQ) estimator for the AR(l) model with additive outliers. In order to down-weight the outliers of X -axis, the Mallows' (1973) weight function has been commonly used in the BIRQ estimator. However, in our Monte Carlo study, the BIRQ estimator using the Tukey's bisquare weight function shows less MSE and bias than that of using the Mallows' weight function or Huber's weight function. Thus, the use of the Tukey's weight function is recommended in the BIRQ estimator for our model.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2005년도 공동학술대회 논문집
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• pp.273-280
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• 2005

MT 전달함수의 추정과정에서 로버스트 방법의 적용은 현재 전자탐사 분야에서 일반적이다. 적절하게 고안되고 적용된 로버스트 방법은 출력 채널인 전기장에 포함되어 있는 외치의 영향을 감소시킬 수 있으나, HLP(High leverage point)라 불리 우는 자기장(입력 채널)의 외치에 종종 민감하지 못하다. 이 문제를 해결하기 위해 HLP의 영향을 최소화할 수 있는 BI(Bounded Influence) 추정이 제안되었고, 전통적인 로버스트 방법보다 신뢰성 있는 전달함수를 제공하는 것으로 보고되었다. 이는 BI 추정이 M-추정을 적용함과 동시에 자기장 성분만으로 결정되는 모자행렬의 통계적인 특성을 고려하여 가중치를 부여하는 방법이기 때문이다. 본 연구에서는 전달함수 추정과정에 BI 추정을 적용하고, 이와 더불어 전처리 단계로서 전자기장의 통계적 분포를 이용해 주파수 영역에서 극단적인 전기장과 자기장 자료의 영향을 감소시키는 기법을 개발하였다. 개발된 전처리 기법은 BI 추정으로 제거될 수 없는 자료를 주파수 영역에서 효과적으로 제거하는 것으로 생각된다. 본 연구에서 개발된 기법의 효율성과 장점은 합성 자료와 현장 자료를 이용하여 도시될 것이다.

• Structural Engineering and Mechanics
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• 제51권4호
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• pp.651-662
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• 2014

The main goal of this study is to extend the domain of influence result to cover the micropolar thermoelastic diffusion. So, we prove that for a finite time t>0 the displacement field $u_i$, the microrotation vector ${\varphi}_i$, the temperature ${\theta}$ and the chemical potential P generate no disturbance outside a bounded domain $B_t$.

• 한국조경학회지
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• 제26권3호
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• pp.90-103
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• 1998

The purposes of this study are to estimate the economic value and reasonable entrance fee of the Yeido Park, which is under construction in Seoul, by conduct the face-to-face interview. A total of 645 daults were selected by two stage cluster sampling. The senario was designed to meet the requirements for doubgle-bounded dichotomous choice CVM, and distributed with the photograph to epict and compare the current and suggested conditions. A donation vehicle and entrance fee were utilized to find the possibility of strategic behaviors and protest zero, and to make the data estimatable tfor interval censored survival analysis. Date was calibrated by the survival analysis to eleminate the 'fat-tail problem'. Weibull distribution was assumed as a baseline distrubution. The mean WTP of donation and entrance fee was ￦5,281 and ￦783, respectively. The economic value of this park was determined by aggregating the mean value, giving a total WTP for the population of ￦36,861,645,000. This economic value was composed with the use value and existence value. The calibrationi of the Weibull proportional hazard model showed that nearness to the park, age, intention to isit the park, and educational attainment were significant independent variable to influence an amount of donation.

• 응용통계연구
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• 제18권1호
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• pp.43-56
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• 2005

본 연구에서는 AR(1) 과정을 따르는 시계열 모형에서 가산적 이상치(Additive Out-lier)가 존재하는 경우, 1차 자기상관계수에 대한 로버스트 추정방법으로 Rupport 와 Carroll (1980)에 의해 회귀모형에서 제안된 L-추정법 형태의 절사최소제곱추정 (PE 추정)방법을 제안하였다. 더불어 X축의 이상치에 대한 비중강하(down-weight)의 방법으로 Mallows의 가중함수를 고려한 유계영향 절사최소제곱 (bounded influence PE, BIPE)추정량을 제안하였으며 모의 실험을 통하여 각 추정량의 효율성을 비교하였다. 모의실험 결과, 다양한 자료의 오염률상에서 일반화 LAD추정치를 예비 추정치로 고려한 BIPE(LAD)-추정량의 효율이 좋은 것으로 나타났다.

• Journal of the Korean Statistical Society
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• 제28권2호
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• pp.265-277
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• 1999

Classical and inverse estimation methods are two well known methods in statistical calibration problems. When there are outliers, both methods have large MSE's and could not estimate the input value correctly. We suggest median calibration estimation based on the LD-statistics. To investigate the robust performances, the influence function of the median calibration estimator is calculated and compared with other methods. When there are outliers in the response variables, the influence function is found to be bounded. In simulation studies, the MSE's for each calibration methods are compared. The estimated inputs as well as the performance of the influence functions are calculated.

• Journal of the Korean Statistical Society
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• 제26권4호
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• pp.507-520
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• 1997

In this paper we propose a robust Wald-type test which is based on an efficient Mallows-type one-step GM-estimator. The proposed estimator based on the weight function of Song, Park and Nam (1996) has a bounded influence function and a high breakdown point. Under some regularity conditions, we compute the finite-sample breakdown point, and drive asymptotic normality of the proposed estimator. The level and power breakdown points, influence function and asymptotic distribution of the proposed test statistic are main points of this paper. To compare the performance of the proposed test with other tests, we perform some Monte Carlo simulations.