• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3401-3420
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• 2021

We provide a traceable ciphertext-policy attribute based encryption (CP-ABE) construction for monotone access structures (MAS) based on composite order bilinear groups, which is secure adaptively under the standard model. We construct this scheme by making use of an "encoding technique" which represents the MAS by their minimal sets to encrypt the messages. To date, for all traceable CP-ABE schemes, their encryption costs grow linearly with the MAS size, the decryption costs grow linearly with the qualified rows in the span programs. However, in our traceable CP-ABE, the ciphertext is linear with the minimal sets, and decryption needs merely three bilinear pairing computations and two exponent computations, which improves the efficiency extremely and has constant decryption. At last, the detailed security and traceability proof is given.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.3
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• pp.121-128
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• 2021

Structures of domestic nuclear power plants are designed to perform elastic behavior against beyond design earthquakes, but studies on the nonlinear behavior of structures have been insufficient since the beyond design earthquake. Accordingly, it is judged that it will be necessary to develop an evaluation method that considers the nonlinear behavioral characteristics to check the safety margin for a standard nuclear power plant structure. It is confirmed that the restoring force characteristics for each member level can be identified through the calculation formula, and the lateral stiffness for each story can also be easily calculated by JEAC 4601. In addition, as a result of applying the evaluation method of JEAC 4601 as a nonlinear restoring force model of the nuclear power plant, a certain degree of safety margin can be identified.

• Structural Engineering and Mechanics
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• v.70 no.2
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• pp.179-197
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• 2019

In this article, the effect of different geometrical, materials and load parameters on the transient response of axisymmetric viscoelastic functionally graded annular plates with different boundary conditions are studied. The behavior of the plate is assumed the elastic in bulk and viscoelastic in shear with the standard linear solid model. Also, the graded properties vary through the thickness according to a power law function. Three types of mostly applied transient loading, i.e., step, impulse, and harmonic with different load distribution respect to radius coordinate are examined. The motion equations and the corresponding boundary conditions are extracted by applying the first order shear deformation theory which are three coupled partial differential equations with variable coefficients. The resulting motion equations are solved analytically using the perturbation technique and the generalized Fourier series. The sensitivity of the response to the graded indexes, different transverse loads, aspect ratios, boundary conditions and the material properties are investigated too. The results are compared with the finite element analysis.

• Communications for Statistical Applications and Methods
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• v.29 no.3
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• pp.333-351
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• 2022

The skew-t distribution is an attractive family of asymmetrical heavy-tailed densities that includes the normal, skew-normal and Student's-t distributions as special cases. In this work, we propose an EM-type algorithm for computing the maximum likelihood estimates for skew-t linear regression models with censored response. In contrast with previous proposals, this algorithm uses analytical expressions at the E-step, as opposed to Monte Carlo simulations. These expressions rely on formulas for the mean and variance of a truncated skew-t distribution, and can be computed using the R library MomTrunc. The standard errors, the prediction of unobserved values of the response and the log-likelihood function are obtained as a by-product. The proposed methodology is illustrated through the analyses of simulated and a real data application on Letter-Name Fluency test in Peruvian students.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.1
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• pp.32-42
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• 2000

This paper presents an on-line learning algorithm for sequential construction of generalized radial basis function networks (GRBFNs) to model nonlinear systems from empirical data. The GRBFN, an extended from of standard radial basis function (RBF) networks with constant weights, is an architecture capable of representing nonlinear systems by smoothly integrating local linear models. The proposed learning algorithm has a two-stage learning scheme that performs both structure learning and parameter learning. The structure learning stage constructs the GRBFN model using two construction criteria, based on both training error criterion and Mahalanobis distance criterion, to assign new hidden units and the linear local models for given empirical training data. In the parameter learning stage the network parameters are updated using the gradient descent rule. To evaluate the modeling performance of the proposed algorithm, simulations and their results applied to two well-known benchmarks are discussed.

• Membrane Journal
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• v.24 no.3
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• pp.249-257
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• 2014

This experiment was carried out for a laboratory scale activated sludge bioreactor equipped with submerged flat sheet membrane using the synthetic wastewater. The membrane system for the activated sludge solution of MLSS 5,000 mg/L was operated with constant permeate flux by continuously permeating and periodically 10 minute-permeating/2 minute-resting modes, respectively. The transmembrane pressure was measured as the permeate flux increased from 10 to $25L/m^2{\cdot}hr$ under the constant air flowrate 0.25 L/min. Also, the complete blocking, standard blocking, intermediate blocking, incompressible cake and linear compressible cake fouling models were retrofitted for the experimental data in order to determine the state of the membrane fouling. Because the transmembrane pressure fluctuated as a pulse shape for every period of 10 minute-permeating/2-minute resting mode, the membrane fouling models were separately applied for the maximum and minimum connecting lines. The linear compressible cake fouling model for the activated sludge cakes was the best fitted with the experimental results from the above five models.

• Korean Journal of Social Welfare
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• v.68 no.3
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• pp.29-50
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• 2016

This study examined the determinants of housing affordability using the 2014 fact-finding survey of housing. This study identified the effects of characters of districts as well as the effects of characters of family and housing, taking advantage of HGLM(Hierarchical General Linear Model). The results of this study showed that male householder, higher education level, the monthly housing, higher satisfaction of environment of housing are the factors that increased the odds of living at unaffordable housing, but higher income, public transfer recipient, living at sub-standard housing, the Jensei housing are the factors that decreased the odds of living at unaffordable housing. And the higher housing price, the higher rent of the districts increased significantly the odds of living at unaffordable housing, but the higher rate of public housing of the districts decreased the odds of living at unaffordable housing. This study provides the basis that the price of housing and rent should be controled and the policy of public housing should be expanded for housing welfare.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.651-669
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• 2018

This study suggests the prediction model to estimate the specific energy of a pick cutter using a gene expression programming (GEP) and particle swarm optimization (PSO). Estimating the performance of mechanical excavators is of crucial importance in early design stage of tunnelling projects, and the specific energy (SE) based approach serves as a standard performance prediction procedure that is applicable to all excavation machines. The purpose of this research, is to investigate the relationship between UCS and BTS, penetration depth, cut spacing, and SE. A total of 46 full-scale linear cutting test results using pick cutters and different values of depth of cut and cut spacing on various rock types was collected from the previous study for the analysis. The Mean Squared Error (MSE) associated with the conventional Multiple Linear Regression (MLR) method is more than two times larger than the MSE generated by GEP-PSO algorithm. The $R^2$ value associated with the GEP-PSO algorithm, is about 0.13 higher than the $R^2$ associated with MLR.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.1-6
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• 2015

This paper investigates the longitudinal flight dynamics and stability of flapping-wing micro air vehicles. Periodic external forces and moments due to the flapping motion characterize the dynamics of this system as NLTP (Non Linear Time Periodic). However, the averaging theorem can be applied to an NLTP system to obtain an NLTI (Non Linear Time Invariant) system which allows us to use a standard eigen value analysis to assess the stability of the system with linearization around a reference point. In this paper, we investigate the dynamics and stability of a hawkmoth-scale flapping-wing air vehicle by establishing an LTI (Linear Time Invariant) system model around a hovering condition. Also, a direct time integration of full nonlinear equations of motion of the flapping-wing micro air vehicle is conducted to see how the longitudinal flight dynamics appear in the time domain beyond the reference point, i.e. hovering condition. In the study, the flapping-wing air vehicle exhibited three distinct dynamic modes of motion in the longitudinal plane of motion: two stable subsidence modes and one unstable oscillatory mode. The unstable oscillatory mode is found to be a combination of a pitching velocity state and a forward/backward velocity state.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.100-108
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• 2023

In hybrid block-based video coding, transform coding converts spatial domain residual signals into frequency domain data and concentrates energy in a low frequency band to achieve a high compression efficiency in entropy coding. The state-of-the-art video coding standard, VVC(Versatile Video Coding), uses DCT-2(Discrete Cosine Transform type 2), DST-7(Discrete Sine Transform type 7), and DCT-8(Discrete Cosine Transform type 8) for primary transform. In this paper, considering that DCT-2, DST-7, and DCT-8 are all linear transformations, we propose an inverse transform that reduces the number of multiplications in the inverse transform by using the linearity of the linear transform. The proposed inverse transform method reduced encoding time and decoding time by an average 26%, 15% in AI and 4%, 10% in RA without the increase of bitrate compared to VTM-8.2.