• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.149-152
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• 2008

In structural design provision, maximum punching shear stress of slabs is prescribed as combined stress of direct shear occurred by balanced gravity load and eccentric shear occurred by unbalanced moment. This means that the effect of unbalanced moment is considered to decide the punching shear stress. However, from the resistance capacity standpoint, the effect of unbalanced moment strength is not considered for deciding punching shear strength. For this problem, a model to show unbalanced moment-punching shear interrelation was proposed. In the model, the relation between load effect and resistance capacity in unbalanced moment-punching shear was two-dimensionally expressed. Using the interrelation model, a method how unbalanced moment strength should be considered to decide the punching shear strength was proposed. Additionally, a effective width enlargement factor for deciding the unbalanced moment strength of flat plates with shear reinforcements was proposed. The interrelation model proposed in this paper is very effective for the design because not only punching shear and unbalanced moment strengths but also failure modes of flat plates can be accurately predicted.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.523-530
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• 2008

In structural design provision, maximum punching shear stress of slabs is prescribed as combined stress in direct shear occurred by gravity load and eccentric shear occurred by unbalanced moment. This means that the effect of unbalanced moment is considered to decide the punching shear stress. However, from the resistance capacity standpoint, the effect of unbalanced moment strength is not considered for deciding punching shear strength. In this paper, a model considering interrelation between unbalanced moment and punching shear was proposed. In the model, the relation between load effect and resistance capacity in unbalanced moment and punching shear was two-dimensionally expressed. Using the interrelation model, a method how unbalanced moment strength should be considered to decide the punching shear strength was proposed. Additionally, effective width enlargement factors for deciding the unbalanced moment strength of flat plates with shear reinforcements were proposed. The interrelation model proposed in this paper is very effective for the prediction of the behavior of slab-column connection because not only punching shear and unbalanced moment strengths but also failure modes of flat plates can be accurately predicted.

• Communications for Statistical Applications and Methods
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• v.28 no.6
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• pp.643-653
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• 2021

Few studies are found in literature on estimation of population quantiles using the method of ranked set sampling (RSS). The optimal RSS strategy is to select observations with at most two fixed rank order statistics from different ranked sets. In this paper, a near optimal unbalanced RSS model for estimating p^th(0 < p < 1) population quantile is proposed. Main advantage of this model is to use each rank order statistics and is distributionfree. The asymptotic relative efficiency (ARE) for balanced RSS, unbalanced optimal and proposed near-optimal methods are computed for different values of p. We also compared these AREs with respect to simple random sampling. The results show that proposed unbalanced RSS performs uniformly better than balanced RSS for all set sizes and is very close to the optimal RSS for large set sizes. For the practical utility, the near optimal unbalanced RSS is recommended for estimating the quantiles.

• Communications for Statistical Applications and Methods
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• v.8 no.3
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• pp.603-613
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• 2001

A test based on score statistic is derived for detecting homoscedasticity of errors in unbalanced random effects linear model. A small simulation study is performed to investigate the finite sample behaviour of the test statistic which is known to have an asymptotic chi-square distribution under the null hypothesis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.305-306
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• 2009

• The Korean Journal of Applied Statistics
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• v.23 no.6
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• pp.1169-1178
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• 2010

This article consider a performance model selection based on AIC under unbalanced deign in linear mixed effect models. Vaida and Balanchard (2005) proposed conditional AIC for model selection in linear mixed effect models when the prediction of random effects is of primary interest. Theoretical properties of cAIC and related criteria have been investigated by Liang et al. (2008) and Greven and Kneib (2010). However, all of the simulation studies were performed under a balanced design. Even though functional form of AIC remain same even under the unbalanced deign, it is worthwhile to investigate performance of AIC based model selection criteria under the unbalanced design. The simulation study in this article shows how unbalancedness affects model selection in linear mixed effect models.

• Communications for Statistical Applications and Methods
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• v.10 no.2
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• pp.361-370
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• 2003

Those who are interested in making inferences concerning linear combination of valiance components in a simple linear regression model with unbalanced nested error structure can use the confidence intervals proposed in this paper. Two approximate confidence intervals for the sum of two variance components in the model are proposed. Simulation study is peformed to compare the methods. The methods are applied to a numerical example and recommendations are given for choosing a proper interval.

• Proceedings of the Korean Statistical Society Conference
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• 2003.05a
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• pp.75-78
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• 2003

Those who are interested in making inferences concerning linear combination of variance components in a simple linear regression model with unbalanced nested error structure can use the confidence intervals proposed in this paper. Two approximate confidence intervals for the sum of two variance components in the model are proposed. Simulation study is peformed to compare the methods.

• Communications for Statistical Applications and Methods
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• v.9 no.2
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• pp.459-471
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• 2002

In applications using a linear regression model with nested error structure, one might be interested in making inferences concerning variance components. This article proposes approximate confidence intervals on the variance component of the primary level in a simple linear regression model with an unbalanced nested error structure. The intervals are compared using computer simulation and recommendations are provided for selecting an appropriate interval.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.403-410
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• 2000

This paper deals with a study to improve the performance of Moving Coil type Linear Oscillatory Actuator (MC-LOA) considering unbalanced magnetic circuit. MC-LOA has an unbalanced magnetic circuit due to its asymmetric structure. In this type of LOA, the airgap flux density tends to have different magnitude along mover's displacement and the current directions. The above property causes eccentric of displacement center and interferes with the proper oscillation of LOA. Therefore, this paper presents two models having the unbalanced magnetic circuit and the other balanced by the saturated core. In order to compare the characteristics between the two models, a characteristic analysis for both the basic model and the improved model is performed by their dynamic analysis composed of kinetic and electric equations and Finite Element Method (FEM). The propriety of the improved model is verified through the experimental results.