• Title/Summary/Keyword: higher order theory

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Progressive failure of symmetrically laminated plates under uni-axial compression

  • Singh, S.B.;Kumar, Ashwini;Iyengar, N.G.R.
    • Structural Engineering and Mechanics
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    • v.5 no.4
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    • pp.433-450
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    • 1997
  • The objective of this work is to predict the failure loads, associated maximum transverse displacements, locations and the modes of failure, including the onset of delamination, of thin, flat, square symmetric laminates under the action of uni-axial compression. Two progressive failure analyses, one using Hashin criterion and the other using Tensor polynomial criteria, are used in conjunction with the finite element method. First order shear deformation theory and geometric nonlinearity in the von Karman sense have been employed. Five different types of lay-up sequence are considered for laminates with all edges simply supported. In addition, two boundary conditions, one with all edges fixed and other with mixed boundary conditions for $(+45/-45/0/90)_{2s}$ quasi-isotropic laminate have also been considered to study the effect of boundary restraints on the failure loads and the corresponding modes of failure. A comparison of linear and nonlinear results is also made for $({\pm}45/0/90)_{2s}$ quasi-isotropic laminate. It is observed that the maximum difference between the failure loads predicted by various criteria depend strongly on the laminate lay-ups and the flexural boundary restraints. Laminates with clamped edges are found to be more susceptible to failure due to the transverse shear and delamination, while those with the simply supported edges undergo total collapse at a load slightly higher than the fiber failure load.

Fashion Designer Competency Modeling (패션디자이너 역량모델링 구축)

  • Jang, Namkyung
    • Fashion & Textile Research Journal
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    • v.20 no.4
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    • pp.369-378
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    • 2018
  • This study started with the need for transition to competency-based education as well as the witness of fast changes in fashion industry's job environment. The goals of this study were (1) to explore fashion designers' competencies that are necessary for a successful careers in global fashion industry, and (2) to establish fashion designer competency model. In-depth individual interviews were conducted with 15 participants who have charged for design department and moreover have shown high performance in national, licence or designer brands in Korea fashion industry. Grounded theory was adopted to analyze data. As a result of analysis, the 4 core competencies emerged: problem-solving, research, inter-personal, and self-development. Each core competency has sub-competencies. Creativity, commerciality, control, decision making were sub-competencies for the problem-solving competency. Information management, innovation understanding & application, trend analysis & forecasting were sub-competencies for the research competency. Consumer, inside company, and outside company relationships were sub-competencies for the inter-personal competency. Self-awareness, self-management, expertise were sub-competencies for the self-development competency. In order to acquire these competencies, knowledge (academic, practical, multi-discipline), skills (sense, analysis, synthesis, communication), and attitude (interest, enjoyment, perseverance, personality) were essential. Based on these findings, implications for university fashion design education and further research areas were suggested.

The Impact of Supplier Induced Demand on Increase in Medical Aid Expenditure (의료급여비용 증가에 공급자 유인효과가 미치는 영향)

  • Shin, Hyunwoung;Yoon, Jangho;Noh, Yunhong;Yeo, Ji-Young
    • Health Policy and Management
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    • v.24 no.1
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    • pp.13-23
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    • 2014
  • Background: A need arises to efficiently control health expenditure for medical aid due to a sharp increase in medical aid expenditure. This study experimently analyzes the impact of physician behavior on medical use for medical aid beneficiaries using supplier induced demand (SID) theory. Methods: This study looks into analyze SID effect using expenditure factor analysis of medical aid for the years between 2003 and 2010 in comparison with health insurance. Moreover, this study analyzes the existence and scale of SID using econometrics modeling with panel data on 16 cities and provinces's health expenditure data for medical aid from 2003 1/4 to 2010 4/4. Results: This study finds that the growth rate of visit days per capita and treatment amount per visit days for medical aid is higher than health insurance. Furthermore, the result of econometrics modeling analysis shows the existence of SID in general hospital, hospital, clinic, oriental clinic. Conclusion: In order to efficiently control expenditure for medical aid, it is required to reinforce macro polices such as the introduction of 'target management' and micro policies such as the strengthen of management on medical institutes in the perspective of suppliers as well as regulations of demanders.

A Study on the Color Collection of Real Image Using the Triplicated Piecewise Bezier Cubic-Curve (3중첩 구간적 베지어 3차 곡선을 이용한 실사 영상의 컬러 보정에 관한 연구)

  • 권희용;이지영
    • The Journal of Information Technology
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    • v.5 no.1
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    • pp.99-111
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    • 2002
  • Due to non-linear characteristics of color spaces, color corrections using linear conversions for real image near color reappearance causes color distortions. In order to overcome this problem, the Bezier Curve, constructed with a set of arbitrary plane in the linear theory, has been used. However, the Bezier Curve increases in proportion to the number of data points, resulting in higher computational complexities. This paper attempts to use a Triplicated Piecewise Bezier Cubic-Curve (TPBC-Curve) of which the degree is cubic on the whole interval while keeping the characteristics of Bezier Curves. By Comparing the TPBC-Curve with Bezier Curve of 20 degree, the paper not only reduces the distortion during color correction but also lessens the relative increase of workload that is caused by the color correction in a small zone.

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A Batch Sizing Model at a Bottleneck Machine in Production Systems (생산라인의 병목공정에서 배치크기 결정 모형)

  • Koo, Pyung-Hoi;Koh, Shie-Gheun
    • Journal of Korean Institute of Industrial Engineers
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    • v.33 no.2
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    • pp.246-253
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    • 2007
  • All of the machines in a production line can be classified into bottleneck and non-bottleneck machines. A bottleneck is a resource whose capacity limits the throughput of the whole production facility. This paper addresses a batch sizing problem at the bottleneck machine. Traditionally, most batch sizing decisions have been made based on the EOQ (economic order quantity) model where setup and inventory costs are considered while throughput rate is assumed to be given. However, since batch size affects the capacity of the bottleneck machine, the throughput rate may not be constant. As the batch size increases, the frequency of the setup decreases. The saved setup time can be transferred to processing time, which results in higher throughput. But, the larger batch size may also result in longer lead time and larger WIP inventory level. This paper presents an alternative method to determine batch size at the bottleneck machine in a manufacturing line. A linear search algorithm is introduced to find optimal throughput rate and batch size at the same time. Numerical examples are provided to see how the proposed method works and to investigate the effects of some parameters.

Differential cubature method for vibration analysis of embedded FG-CNT-reinforced piezoelectric cylindrical shells subjected to uniform and non-uniform temperature distributions

  • Madani, Hamid;Hosseini, Hadi;Shokravi, Maryam
    • Steel and Composite Structures
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    • v.22 no.4
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    • pp.889-913
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    • 2016
  • Vibration analysis of embedded functionally graded (FG)-carbon nanotubes (CNT)-reinforced piezoelectric cylindrical shell subjected to uniform and non-uniform temperature distributions are presented. The structure is subjected to an applied voltage in thickness direction which operates in control of vibration behavior of system. The CNT reinforcement is either uniformly distributed or functionally graded (FG) along the thickness direction indicated with FGV, FGO and FGX. Effective properties of nano-composite structure are estimated through Mixture low. The surrounding elastic foundation is simulated with spring and shear constants. The material properties of shell and elastic medium constants are assumed temperature-dependent. The motion equations are derived using Hamilton's principle applying first order shear deformation theory (FSDT). Based on differential cubature (DC) method, the frequency of nano-composite structure is obtained for different boundary conditions. A detailed parametric study is conducted to elucidate the influences of external applied voltage, elastic medium type, temperature distribution type, boundary conditions, volume percent and distribution type of CNT are shown on the frequency of system. In addition, the mode shapes of shell for the first and second modes are presented for different boundary conditions. Numerical results indicate that applying negative voltage yields to higher frequency. In addition, FGX distribution of CNT is better than other considered cases.

H$_{\infty}$ Control System for Tandem Cold Mills with Roll Eccentricity

  • Kim, Seung-Soo;Kim, Jong-Shik;Yang, Soon-Yong;Lee, Byung-Ryong;Ahn, Kyung-Kwan
    • Journal of Mechanical Science and Technology
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    • v.18 no.1
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    • pp.45-54
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    • 2004
  • In order to meet the requirement for higher thickness accuracy in cold rolling processes, it is strongly desired to have high performance in control units. To meet this requirement, we have considered an output regulating control system with a roll-eccentricity estimator for each rolling stand of tandem cold mills. Considering entry thickness variation as well as roll eccentricity as the major disturbances, a synthesis of multivariable control systems is presented based on H$\sub$$\infty$/ control theory, which can reflect the knowledge of input direction and spectrum of disturbance signals on the design. Then, to reject roll eccentricity effectively, a weight function having some poles on the imaginary axis is introduced. This leads to a non-standard H_ control problem, and the design procedures for solving this problem are analytically presented. The effectiveness of the proposed control method is evaluated through computer simulations and compared to that of the conventional LQ control and feedforward control methods for roll eccentricity.

Vibration and instability analysis of pipes reinforced by SiO2 nanoparticles considering agglomeration effects

  • Golabchi, Hadi;Kolahchi, Reza;Bidgoli, Mahmood Rabani
    • Computers and Concrete
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    • v.21 no.4
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    • pp.431-440
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    • 2018
  • Fluid velocity analysis on the instability of pipes reinforced by silica nanoparticles ($SiO_2$) is presented in this paper. Mori-Tanaka model is used for obtaining the effective materials properties of the nanocomposite structure considering agglomeration effects. The well known Navier-Stokes equation is used for obtaining the applied force of fluid to pipe. Based on the Reddy higher-order shear deformation theory, the motion equations are derived based on energy method and Hamilton's principal. The frequency and critical fluid velocity of structure are calculated using differential quadrature method (DQM) so that the effects of different parameters such as volume fractions of SiO2 nanoparticles, SiO2 nanoparticles agglomeration, boundary conditions and geometrical parameters of pipes are considered on the nonlinear vibration and instability of the pipe. Results indicate that increasing the volume fractions of SiO2 nanoparticles, the frequency and critical fluid velocity of the structure are increased. Furthermore, considering SiO2 nanoparticles agglomeration, decreases the frequency and critical fluid velocity of the pipe.

Moving load induced dynamic response of functionally graded-carbon nanotubes-reinforced pipes conveying fluid subjected to thermal load

  • Tahami, F. Vakili;Biglari, H.;Raminnea, M.
    • Structural Engineering and Mechanics
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    • v.64 no.4
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    • pp.515-526
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    • 2017
  • Dynamic response of functionally graded Carbon nanotubes (FG-CNT) reinforced pipes conveying viscous fluid under accelerated moving load is presented. The mixture rule is used for obtaining the material properties of nano-composite pipe. The radial force induced by viscous fluid is calculated by Navier-Stokes equation. The material properties of pipe are considered temperature-dependent. The structure is simulated by Reddy higher-order shear deformation shell theory and the corresponding motion equations are derived by Hamilton's principal. Differential quadrature (DQ) method and the Integral Quadrature (IQ) are applied for analogizing the motion equations and then the Newmark time integration scheme is used for obtaining the dynamic response of structure. The effects of different parameters such as boundary conditions, geometrical parameters, velocity and acceleration of moving load, CNT volume percent and distribution type are shown on the dynamic response of pipe. Results indicate that increasing CNTs leads to decrease in transient deflection of structure. In accelerated motion of the moving load, the maximum displacement is occurred later with respect to decelerated motion of moving load.

MULTIDIMENSIONAL TEACHING: THOUGHTFUL WAYS OF CREATING A FLIPPED CLASSROOM

  • Cho, Hoyun;Osborne, Carolyn;Sanders, Tobie;Park, KyungEun
    • Korean Journal of Mathematics
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    • v.23 no.1
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    • pp.93-114
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    • 2015
  • The "flipped" or "inverted" classroom, in which students study lecture-type material at home and do their "homework" in the classroom, has been the subject of research, particularly in the area of student achievement. Yet Bishop and Verleger (2013) state the need for an underlying theory to the practice. The purpose of this paper is to explore "multidimensional teaching," the authors' extension of the two-dimensional "flipped" classroom concept in light of Cambourne's (1995) Conditions for Learning. One author's math class for pre-service teachers was taught in two styles, a more traditional lecture format and in the \inverted" format. Students in the "flipped" format achieved at a higher level. Moreover, students' open-ended comments reveal that Cambourne's Conditions for Learning were implicit to the teaching practice. The authors suggest that practitioners of this style of teaching should deliberately develop student-centered practices, such as those mentioned by Cambourne, in order to retain the power that this teaching style currently has.