• Title/Summary/Keyword: stability measure

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MEASURES FOR STABILITY OF SLOPE ESTIMATION ON THE SECOND ORDER RESPONSE SURFACE AND EQUALLY-STABLE SLOPE ROTATABILITY

  • Park, Sung H.;Kang, Ho-Seog;Kang, Kee-Hoon
    • Journal of the Korean Statistical Society
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    • v.32 no.4
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    • pp.337-357
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    • 2003
  • This paper introduces new measures for the stability of slope estimation on the second order response surface at a point and on a sphere. As a measure of point stability of slope estimation, we suggest a point dispersion measure of slope variances over all directions at a point. A spherical dispersion measure is also proposed as a measure of spherical stability of slope estimation on each sphere. Some designs are studied to explore the usefulness of the proposed measures. Using the point dispersion measure, another concept of slope rotatability called equally-stable slope rotatability is proposed as a useful property of response surface designs. We provide a set of conditions for a design to have equally-stable slope rotatability.

A Comparison of Various Governing Parameters on Hydrodynamic Stability in Interface on Small Solar Pond (소형태양수구내(小型太陽水構內) 중간경계면(中間境界面)에서 수력학적(水力學的) 안정(安定)에 관(關)한 각종(各種) 지배변수(支配變數)의 비교(比較))

  • Park, Ee-Dong
    • Solar Energy
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    • v.5 no.2
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    • pp.11-19
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    • 1985
  • In this paper, the interface stability not to occur mixing and entrainment between the adjacent layers has been studied in the case of the selective withdrawal of a stratum and the injection in stratified fluid formed by the density difference in a small solar pond. There are stability parameter, Richardson number, Rayleigh number and Froude number as the parameters governing stability in order to measure the interface stability on the stratified fluid. The model which could measure the interface stability on the stratified fluid was the small solar pond composed by 1 meters wide, 2 meters high, and 5 meters long. In order to measure the interface stability on the stratified fluid at the inlet port, the middle section and the outlet port, Richardson number, Rayleigh number, and Froude number involved in the parameters governing the stability were calculated by means of the data resulted from the test of the study on hydrodynamic stability between the convective and nonconvective layers in that solar pond. Richardson number written by the ratio of inertia force to buoyancy force can be used in order to measure the stability on the stratified fluid related to the buoyancy force generated from the injection of fluid. Rayleigh number written by the product of Grashof number by Prandtl number can be used in order to measure the stability of the fluid related to the heat flux and diffusivity of viscosity. Froude number written by the ratio of gravity force to inertia force can be used in order to measure the stability of the nonhomogeneous fluid related to the density difference. As the result of calculating the parameters governing stability, the interface stability on the stratified fluid couldn't be identified below the 70cm height from the bottom of the solar pond, but it could be identified above the 70cm height from it at the inlet port, the middle section and the outlet port. When compared with such the three parameters as Richardson number, Rayleigh number, Froude number, the calculated result was in accord with them at inlet port, the middle section and the outlet port. Henceforth, it is learned that even though any of the three parameters is used for the purpose of measuring the interface stability on the stratified fluid, the result will be the same with them. It is concluded that all the use of Richardson number, Rayleigh number, and Froude number, is desirable and infallible to measure the interface stability on the stratified fluid in the case of considering the exist of the fluid flow and the heat flux like the model of the solar pond.

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Design of a Mechanism to Increase Lateral Stability of Mobile Robot (이동로봇의 횡방향 안정성 증대를 위한 기구)

  • 정상국;최용제
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.1148-1153
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    • 2004
  • This paper presents the mechanism to increase lateral stability of a mobile robot using an energy stability margin theory. Previous measure of stability used in a wheeled mobile robot has been based on a static stability margin. However, the static stability margin is independent of the height of the robot and does not provide sufficient measure for the amount of stability when the terrain is not a horizontal plane. In this work, the energy stability margin theory, which is dependent on robot's height is used to develop a 2 dof mechanism to increase lateral stability. This proposed mechanism shifts the center of gravity of the robot to the point where the energy stability margin is maximized and overall stability of the robot equipped with this mechanism will be increased.

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Interpretability Comparison of Popular Decision Tree Algorithms (대표적인 의사결정나무 알고리즘의 해석력 비교)

  • Hong, Jung-Sik;Hwang, Geun-Seong
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.44 no.2
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    • pp.15-23
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    • 2021
  • Most of the open-source decision tree algorithms are based on three splitting criteria (Entropy, Gini Index, and Gain Ratio). Therefore, the advantages and disadvantages of these three popular algorithms need to be studied more thoroughly. Comparisons of the three algorithms were mainly performed with respect to the predictive performance. In this work, we conducted a comparative experiment on the splitting criteria of three decision trees, focusing on their interpretability. Depth, homogeneity, coverage, lift, and stability were used as indicators for measuring interpretability. To measure the stability of decision trees, we present a measure of the stability of the root node and the stability of the dominating rules based on a measure of the similarity of trees. Based on 10 data collected from UCI and Kaggle, we compare the interpretability of DT (Decision Tree) algorithms based on three splitting criteria. The results show that the GR (Gain Ratio) branch-based DT algorithm performs well in terms of lift and homogeneity, while the GINI (Gini Index) and ENT (Entropy) branch-based DT algorithms performs well in terms of coverage. With respect to stability, considering both the similarity of the dominating rule or the similarity of the root node, the DT algorithm according to the ENT splitting criterion shows the best results.

Local Dynamic Stability Associated with Load Carrying

  • Liu, Jian;Lockhart, Thurmon E.
    • Safety and Health at Work
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    • v.4 no.1
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    • pp.46-51
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    • 2013
  • Objectives: Load carrying tasks are recognized as one of the primary occupational factors leading to slip and fall injuries. Nevertheless, the mechanisms associated with load carrying and walking stability remain illusive. The objective of the current study was to apply local dynamic stability measure in walking while carrying a load, and to investigate the possible adaptive gait stability changes. Methods: Current study involved 25 young adults in a biomechanics research laboratory. One tri-axial accelerometer was used to measure three-dimensional low back acceleration during continuous treadmill walking. Local dynamic stability was quantified by the maximum Lyapunov exponent (maxLE) from a nonlinear dynamics approach. Results: Long term maxLE was found to be significant higher under load condition than no-load condition in all three reference axes, indicating the declined local dynamic stability associated with load carrying. Conclusion: Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying.

A MEASURE ZERO STABILITY OF A FUNCTIONAL EQUATION ASSOCIATED WITH INNER PRODUCT SPACE

  • Chun, Jaeyoung;Rassias, John Michael
    • Journal of the Korean Mathematical Society
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    • v.54 no.2
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    • pp.697-711
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    • 2017
  • Let X, Y be real normed vector spaces. We exhibit all the solutions $f:X{\rightarrow}Y$ of the functional equation f(rx + sy) + rsf(x - y) = rf(x) + sf(y) for all $x,y{\in}X$, where r, s are nonzero real numbers satisfying r + s = 1. In particular, if Y is a Banach space, we investigate the Hyers-Ulam stability problem of the equation. We also investigate the Hyers-Ulam stability problem on a restricted domain of the following form ${\Omega}{\cap}\{(x,y){\in}X^2:{\parallel}x{\parallel}+{\parallel}y{\parallel}{\geq}d\}$, where ${\Omega}$ is a rotation of $H{\times}H{\subset}X^2$ and $H^c$ is of the first category. As a consequence, we obtain a measure zero Hyers-Ulam stability of the above equation when $f:\mathbb{R}{\rightarrow}Y$.

NEW RESULTS ON STABILITY PROPERTIES FOR THE FEYNMAN INTEGRAL VIA ADDITIVE FUNCTIONALS

  • Lim, Jung-Ah
    • Journal of the Korean Mathematical Society
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    • v.39 no.4
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    • pp.559-577
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    • 2002
  • It is known that the analytic operator-valued Feynman integral exists for some "potentials" which we so singular that they must be given by measures rather than by functions. Corresponding stability results involving monotonicity assumptions have been established by the author and others. Here in our main theorem we prove further stability theorem without monotonicity requirements.

Nonquadratic Stability Condition of Continuous Fuzzy Systems

  • Kim, Eun-Tai;Park, Min-Kee
    • Journal of the Korean Institute of Intelligent Systems
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    • v.13 no.5
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    • pp.596-599
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    • 2003
  • In this paper, a new asymptotic stability condition of continuous fuzzy system is proposed. The new stability condition considers the nonquadratic stability by using the P-matrix measure. Later the relationship of the suggested stability condition and the well-known stability condition is discussed and it is shown in a rigorous manner that the proposed criterion includes the conventional conditions.

EXPANDING MEASURES FOR HOMEOMORPHISMS WITH EVENTUALLY SHADOWING PROPERTY

  • Dong, Meihua;Lee, Keonhee;Nguyen, Ngocthach
    • Journal of the Korean Mathematical Society
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    • v.57 no.4
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    • pp.935-955
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    • 2020
  • In this paper we present a measurable version of the Smale's spectral decomposition theorem for homeomorphisms on compact metric spaces. More precisely, we prove that if a homeomorphism f on a compact metric space X is invariantly measure expanding on its chain recurrent set CR(f) and has the eventually shadowing property on CR(f), then f has the spectral decomposition. Moreover we show that f is invariantly measure expanding on X if and only if its restriction on CR(f) is invariantly measure expanding. Using this, we characterize the measure expanding diffeomorphisms on compact smooth manifolds via the notion of Ω-stability.