• Communications for Statistical Applications and Methods
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• v.6 no.2
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• pp.511-522
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• 1999

The paper considers the problem of robustness in hierarchical bayesian models. In specific we address Bayesian robustness in the estimation of normal means. We provide the ranges of the posterior means under $\varepsilon$-contamination class as well as the density ratio class of priors. For the class of priors that are uniform over a specified interval we investigate the sensitivity as to the choice of the intervals. The methods are illustrated using the famous baseball data of Efron and Morris(1975).

• Journal of the Korea Society of Computer and Information
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• v.28 no.4
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• pp.83-91
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• 2023

In this paper, we propose a robustness sensitivity index (RSI) of highway networks to analyze the effect of congestion in a specific section on the entire highway. The newly proposed RSI is defined as the change in the total mileage of the transportation network per extended unit length when the length of a particular section is extended. When the RSI value is large, traffic congestion in the section has a worse effect on the entire network than in other sections. The existing network robustness index (NRI) simply observes changes in transportation networks with and without specific sections, but the RSI proposed in this study is a kind of performance indicator that allows quantitative analysis of the ripple effect of the entire network according to the degree of congestion in a specific section. While changing the degree of congestion in a particular section, it is possible to calculate how the traffic volume increases, decreases, and the size and location of the congestion section change. This analysis proves the superiority of RSI as it cannot be analyzed with NRI. Various properties of RSI are analyzed using data from the domestic highway network. In addition, using the RSI concept, it is shown that the ripple effect on other sections in which a change in the degree of congestion of a specific section occurs can be analyzed.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.205-210
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• 2000

An optimum design algorithm of PSC box girder bridges using design sensitivity analysis is proposed in this paper. For the efficiency of the proposed algorithm, approximated reanalysis techniques using design sensitivity analysis are introduced. And also to save the numerical efforts, an efficient reanalysis technique through approximated structural responses is proposed. A design sensitivity analysis of structural response is executed by automatic differentiation(AD). The efficiency and robustness of the proposed algorithm, compared with conventional algorithm, is successfully demonstrated in the numerical example.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.185-190
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• 1991

In this paper, we present a method of analising a system with nonlinear parameter by pole sensitivity defined by the rate of pole movement with respect of non-linear parameter variation. Pole sensitivity give us not only the rate of pole movement but also the directional information. We present a method of design of a state feedback for a system with nonlinear system parameter by considering the pole sensitivity and show that the suggested method guarantee the stability robustness for a system with nonlinear parameter, parameter perturbation and urimodelled dynamics.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.446-450
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• 1990

In this paper, we present a method of analysing perturbed linear system by pole sensitivity defined by the rate of pole movement with respect of perturbation. Pole sensitivity give us not only the rate of pole movement but also the directional information of the pole movement. We present a method of design of a LQR by considering the pole sensitivity and show that the suggested method guarantee the stability robustness of parameter perturbation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1426-1435
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• 2003

Design goal is to find the one that has the highest probability of success and the smallest variation. A robustness index has been proposed to satisfy these conditions. The two-step optimization process of the target problem requires a scaling factor. The search process of a scaling factor is replaced with the making of the decoupled design between the mean and the standard deviation. The decoupled design matrix is formed from the sensitivity or the sum of squares. After establishing the design matrix, the robust design process has a new three-step one. The first is ″reduce variability,″ the second is ″make the candidate designs that satisfy constraints and move the mean on the target,″ and the final is ″select the best robust design using the proposed robustness index.″ The robust design process is verified by three examples and the results using the robustness index are compared with those of other indices.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.110-113
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• 2006

This paper describes the development process of body and full vehicle for reduced idle vibration through the data level of frequency and sensitivity. The vibration mode map is used to separate body structure modes from resonance of engine idle nm and steering system. This paper describes the analysis approach process to reduce the variation of uncertainties for idle vibration performance at initial design stage. The robust design method is performed to increase the stabilization performance under vehicle vibration. It is used to predict the effects of the stiffness deviation according to the spot welding condition of the body structure. The tolerance associated with hood over slam bumper is analyzed for the quality deviation of the moving system in full vehicle. And the glass sealant stiffness and weight difference is considered for the deviation characteristic. The design guideline is suggested considering sensitivity about body and full vehicle by using mother car at initial design stage. It makes possible to design the good NVH performance and save vehicles to be used in tests. These improvements can lead to shortening the time needed to develop better vehicles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1931-1942
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• 2002

In this paper a formulation of robust optimization is presented and illustrated by a design example of vibratory micro gyroscopes in order to reduce the effect of variations due to uncertainties in MEMS fabrication processes. For the vibratory micro gyroscope considered it is important to match the resonance frequencies of the vertical (sensing) and lateral (driving) modes as close as possible to attain a high sensing sensitivity. A deterministic optimization in which the difference of both the sensing and driving natural frequencies is minimized as an objective function results in highly enhanced performance but apt to be very sensitive to fabrication errors. The formulation proposed is to attain robustness of the performance by including the sensitivity of the response with respect to uncertain variables as a term of objective function to be minimized. This formulation is simple and practically applicable since no detail statistical information on fabrication errors is required. The geometric variables, beam width, length and thickness of vibratory micro gyroscopes are adopted as design variables and at the same time considered as uncertain variables because here occur the fabrication errors. A robustness test in terms of a percentage yield by using the Monte Carlo simulation has shown that the robust optimum produces twice more acceptable designs than the deterministic optimum. Improvement of robustness becomes bigger as the amount of fabrication errors is assumed larger. Considering that the magnitude of fabrication errors and uncertainties in a MEMS structure are comparatively large, the present method is illustrated to be a viable approach for a robust MEMS design.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.264-269
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• 2014

We consider transmission over body area networks. Due to the difficulty in assessing an accurate statistical model valid for multiple scenarios, we advocate a system design technique favoring robustness. Our approach, which is based on results in [12] and generalizes them, examines the variation of a performance metric when the nominal statistical distribution of fading is replaced by the worst distribution within a given Kullback-Leibler divergence from it. The sensitivity of the performance metric to the divergence from the nominal distribution can be used as an indication of the design robustness. This concept is applied by evaluating the error probability of binary uncoded modulation and the outage probability-the first parameter is useful to assess system performance with no error-control coding, while the second reflects the performance when a near-optimal code is used. The usefulness of channel coding can be assessed by comparing its robustness with that of uncoded transmission.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.133-139
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• 2011

Maintaining adequate sealing in engine cylinder head is a crucial factor in engine design. Failure of engine operations occurs mainly owing to the leaking by decreased sealing pressure. Reliability-robustness concept is applied to the engine cylinder head system. Deterministic way to obtain engineering solution in CAE industry may not consider the effects of noises and disturbances experienced during operation. However, analytical reliability-robustness concept may make possible to reduce the sensitivity of system with noise factors. Influences of design factors including noise factors would be predicted in analytical way. Optimized design may be obtained by shrinking variability and shifting to design target. Three-dimensional finite element analyses have been performed to apply analytical reliability-robustness concept.