• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1007-1011
• /
• 2003

In this paper, a design of I-PDA controller by CDM to control a flow process whose structure is first order lag plus a dead time is introduced. The factor of dead time of the process is approximated by second order Pade approximation in order to get a third order system. The simulations show that both of the transient and steady state specifications can be fulfilled. However, the transient response of the I-PDA control system still has long rise time. Then, a feedforward controller (FFC) with two adjustable parameters and one derivative time is introduced into I-PDA control system for improving the speed of the system response. It is shown, from the simulation results, that the performance of the I-PDA control system with suitable FFC has shorter rise time and no overshoot, while settling time remains almost the same. The performance comparison of the proposed control system with the PI control system with and without FFC is also made.

• Steel and Composite Structures
• /
• v.24 no.2
• /
• pp.151-176
• /
• 2017

This paper deals with general equations of motion for free vibration analysis response of thick three-layer doubly curved sandwich panels (DCSP) under simply supported boundary conditions (BCs) using higher order shear deformation theory. In this model, the face sheets are orthotropic laminated composite that follow the first order shear deformation theory (FSDT) based on Rissners-Mindlin (RM) kinematics field. The core is made of orthotropic material and its in-plane transverse displacements are modeled using the third order of the Taylor's series extension. It provides the potentiality for considering both compressible and incompressible cores. To find these equations and boundary conditions, Hamilton's principle is used. Also, the effect of trapezoidal shape factor for cross-section of curved panel element ($1{\pm}z/R$) is considered. The natural frequency parameters of DCSP are obtained using Galerkin Method. Convergence studies are performed with the appropriate formulas in general form for three-layer sandwich plate, cylindrical and spherical shells (both deep and shallow). The influences of core stiffness, ratio of core to face sheets thickness and radii of curvatures are investigated. Finally, for the first time, an optimum range for the core to face sheet stiffness ratio by considering the existence of in-plane stress which significantly affects the natural frequencies of DCSP are presented.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.10
• /
• pp.97-102
• /
• 2004

In this paper, a new predistorter controlling modified individual order jntermodulation distortion signals is proposed. The proposed predistorter generates and controls predistorted third and high order IM signals independently. Using predistorted signals, jntermodulation distortion signals of power amplifier are suppressed effectively. The predistortion linearizer has been implemented to operate in Korean PCS basestation transmitting band (1840～1870MHz). The test results show that IMD3 and IMD5 (C/I) of power amplifier are improved more than 40dB and 23dB for CW two tone signals, respectively. The predistorter improves the adjacent channel power ratio (ACPR) more than 10dB at 885KHz offset point for CDMA (IS-95) signals.

• Investigative Magnetic Resonance Imaging
• /
• v.4 no.1
• /
• pp.20-26
• /
• 2000

Gradient moment nulling techniques require the introduction of an additional gradient on each axis for each order of motion correction to be applied. The additional gradients introduce new constraints on the sequence design and increase the demands on the gradient system. The purpose of this paper is to demonstrate techniques for optimization of gradient echo gradient moment nulling sequences within the constraints of the gradient hardware. Flow compensated pulse sequences were designed and implemented on a clinical magnetic resonance imaging system. The design of the gradient moment nulling sequences requires the solution of a linear system of equations. A Mathematica package was developed that interactively solves the gradient moment nulling problem. The package allows the physicist to specify the desired order of motion compensation and the duration of the gradients in the sequence with different gradient envelopes. The gradient echo sequences with first, second, and third order motion compensation were implemented with minimum echo time. The sequences were optimized to take full advantage of the capabilities of the gradient hardware. The sequences were used to generate images of phantoms and human brains. The optimized sequences were found to have better motion compensation than comparable standard sequences.

• Structural Engineering and Mechanics
• /
• v.44 no.1
• /
• pp.15-34
• /
• 2012

In the present paper, an improved high-order theory is used for bending analysis of soft-core sandwich plates. Third-order plate assumptions are used for face sheets and quadratic and cubic functions are assumed for transverse and in-plane displacements of the orthotropic soft core. Continuity conditions for transverse shear stresses at the interfaces as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of the plate are satisfied. Also, transverse flexibility and transverse normal strain and stress of the orthotropic core are considered. The equations of motion and boundary conditions are derived by principle of minimum potential energy. Analytical solution for bending analysis of simply supported sandwich plates under various transverse loads are presented using Navier's solution. Comparison of the present results with those of the three-dimensional theory of elasticity and some plate theories in the literature confirms the accuracy of the proposed theory.

• The Research Journal of the Costume Culture
• /
• v.26 no.6
• /
• pp.872-887
• /
• 2018

This study aims to identify the differences between Korean and Chinese and males and females in terms of female image preferences. The survey was conducted for 1 month targeting male and female Korean and Chinese subjects. Among the 350 completed questionnaires, 309 were used for analysis. For the analysis, 11 female images were chosen based on theoretical study, then a t-test and a paired t-test were carried out using SPSS 19.0. The results of this study are as follows: First, differences in female image preferences were observed to depend on nationality and gender. Koreans prefer urban images while Chinese prefer cute, intelligent, and sexy images. Second, males prefer innocent or sexy images, while females prefer sophisticated images. Third, Korean males prefer innocent, active, sophisticated, gentle, cute, sexy, urban, natural, intelligent, spectacular, and neutral images in order. Chinese males prefer gentle, innocent, sexy, active, sophisticated, intelligent, cute, natural, urban, spectacular, and neutral images in order. Fourth, Korean females prefer sophisticated, gentle, urban, natural, intelligent, innocent, active, sexy, cute, spectacular, and neutral images in order. Chines females prefer sophisticated, intelligent, cute, gentle, innocent, active, natural, sexy, urban, spectacular, and neutral images in order. Using these results, it will be possible to design marketing strategies for global consumers.

• Journal of Distribution Science
• /
• v.18 no.12
• /
• pp.5-13
• /
• 2020

Purpose: The objective of this study is to explore and prioritize strategic factors for revitalization of the sports contents distribution industry. Research design, data and methodology: To this end, strategic factors for revitalization of the sports contents distribution industry were explored based on literature review, and 14 experts were consulted to prioritize the factors. Results: Major conclusions deduced are the following: First, the factors were prioritized in order of legal policy factors, contents factors, and technical infrastructure factors. Second, subdomains of legal policy factors were prioritized in order of policy process factors, legislation enactment and revision factors, budget factors, business model factors focusing on sports contents. Third, subdomains of contents factors were prioritized in order of humanware contents factors, sports contents diversification factors, and high-quality sports contents production factors. Fourth, subdomains of technical infrastructure factors were prioritized in order of sports contents service platform factors, technical development and standardization, global distribution channel provision, and distribution metadata standardization. Conclusions: Findings of this study are of significance given that this study stratifies factors of sports contents distribution industry revitalization-about which there have been very few previous studies- analyzed mainly in terms of justifiability and timeliness, and presents preferential business strategies.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.4
• /
• pp.53-59
• /
• 2022

In this study, an enhanced first-order shear deformation theory is proposed to efficiently and accurately predict the thermo-mechanical-viscoelastic coupled behavior of laminated composite structures. To this end, transverse shearstress and displacement fields are independently assumed, and the strain-energy relationship between these fields issystematically established using the mixed variational theorem (MVT). In MVT, the transverse shear stress fields are obtained from the third-order zigzag model, whereas the displacement fields of the conventional first-order model are considered to amplify the benefits of numerical efficiency. Additionally, a transverse displacement field with a smooth parabolic distribution is introduced to accurately predict the thermal behavior of composite structures. Furthermore, the concept of Laplace transformation is newly employed to simplify the viscoelastic problem, similar to the linear-elastic problem. To demonstrate the performance of the proposed theory, the numerical results obtained herein were compared with those available in the literature.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.9
• /
• pp.907-913
• /
• 2012

High-order perturbation solutions have been obtained for the simple physical model describing the liquid pool spreading with a continuous spill, and these are shown to improve over first-order perturbation solutions. The non-dimensional governing equations for the model are derived to obtain more general solutions. Non-dimensional parameters are sought as the governing parameters for the non-dimensional equations, and the non-dimensional evaporation rate is used as the perturbation parameter. The results show that the high-order solutions exhibit an improvement over the first-order solutions with respect to the pool volume as well as the spreading radius. In addition, as the order of the perturbation solutions increases, the difference between the numerical solutions and the perturbation solutions is significantly reduced. Finally, it is revealed that the third-order solutions are reasonable because they almost agree with the numerical solutions.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.4 s.33
• /
• pp.601-609
• /
• 1997

Bending and vibration results for a laminated plate base on a simplified higher-order plate theory with four variables are presented. Assuming a constant in-plane rotation tensor through the thickness in Reddy's higher-order shear deformation theory it is shown that a simpler higher-order theory can be obtained with the reduction of one variable without significant loss in the accuracy. This simple higher-order shear deformation theory is then used for predicting the natural frequencies and deflection of simply-supported laminated composite plates. The results obtained for antisymmetrical laminated composite plates compare favorably with third-order and first-order shear deformation theory. The information presented should be useful to composite-structure designers, to researchers seeking to obtain better correlation between theory and experiment and to numerical analysts in checking out their programs.