• 한국식생활문화학회지
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• 제28권1호
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• pp.89-98
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• 2013

The purpose of this study was to develop measures for establishing and enforcing legal nutrition labeling for Takju based on results from consumer awareness surveys, statistical model development, and evaluation of nutrients. The statistical model developed with consumer survey results showed that consumers would like to know the nutrients they intake from drinking Takju, as their awareness about Takju was low. Specifically, consumers would like to see information regarding alcohol content, calories, carbohydrates, and saccharides on the label. Structural equations from the research model showed that consumers who had some knowledge of Takju also had positive thoughts of the nutrition fact labels for Takju. Evaluation of nutrients in Takju showed that the starch sources and other ingredients used in Takju fermentation did not influence nutrient facts, and nutrient concentrations also varied among the different Takju. In addition, this research suggests methods for consumers to make reasonable selections and to inform them of the nutrition fact labeling for Takju. Benners and pop-up were manufactured to promote voluntary participation of companies and to provide nutrition facts from Takju. Eventually, a measure was suggested to establish and enforce nutrition labeling, using results from consumer and nutrient surveys of Takju.

• 한국전산구조공학회논문집
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• 제37권2호
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• pp.85-93
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• 2024

이 논문에서는 파랑 하중을 받는 부유식 구조체의 운동 해석에 있어서 시스템 식별 방법을 이용한 상태공간방정식 모델을 수립하고 해석하는 방법을 제안하였다. 상태공간방정식 모델의 수립 방법으로는 주파수영역에서 하중-변위 입출력 관계에 대한 목표 전달함수를 구하고 이에 가장 근접하는 상태공간방정식을 구하는 절차를 제시하였다. 전통적으로 부유식 구조체 운동의 시간영역 해석은 지연함수의 합성곱적분을 포함하는 Cummins 방정식을 시간적분하여 이루어진다. 상태공간방정식 모델은 이러한 시간영역해석을 효과적으로 수행하기 위한 방법의 하나로서 연구되어 왔다. 제안하는 방법에서는 시스템 식별방법인 N4SID 와 전달함수의 분모 및 분자 다항식의 계수를 설계변수로 하는 최적화방법을 사용하여 목표 전달함수에 상응하는 상태공간방정식을 구한다. 제안하는 방법의 적용성을 보이는 예제로서 단자유도 수치모델 및 6자유도 바지의 운동을 해석하였다. 제시하는 상태공간방정식 모델은 주파수영역 및 시간영역에서 모두 기존의 해석결과와 잘 일치하고 시간영역해석에서는 계산의 정확도를 확보하면서 계산 시간을 크게 줄일 수 있음을 확인하였다.

• 한국강구조학회 논문집
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• 제19권5호
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• pp.515-526
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• 2007

본 연구에서는 시공간의 구조안전도 확보와 교량붕괴를 방지하기 위해 FCM과 FSM공법으로 가설되는 강-콘크리트 복합사장교의 안전도평가 모형을 제안하였다. 구조물의 저항과 하중효과에 내제된 각종 불확실성을 합리적으로 고려하는 구조신뢰성이론에 의해 강합성거더와 콘크리트거더가 연결된 강-콘크리트 복합사장교의 저항과 하중의 분포특성을 정의하고 가설중 영구구조물과 가설구조물의 강도한계상태방정식을 제안하였다. 케이블, 주탑, 거더, 강-콘크리트 접합부 및 가설벤트의 신뢰성해석을 위해 AFOSM 알고리즘과 MCS 기법을 사용하였다. 또한, 가설단계별 구조시스템에 따라 요소신뢰성해석을 수행하였다. 제안된 평가모형의 타당성과 실용성을 검증하기 위하여 제시된 방법을 실제 교량에 적용하였다. 유사한 교량의 안전도 관리를 위한 중점 항목을 정의하기 위해서 주요 인자에 대한 민감도 분석이 수행되었다. 본 연구를 통해, 제안된 모형은 FCM과 FSM으로 가설되는 강-콘크리트 복합사장교의 시공간 안전도 평가를 위한 합리적이고 실용적인 방법으로 적용될 수 있을 것으로 판단되었다.

• Advances in aircraft and spacecraft science
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• 제1권3호
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• pp.291-310
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• 2014

An advanced model for the linear flutter analysis is introduced in this paper. Higher-order beam structural models are developed by using the Carrera Unified Formulation, which allows for the straightforward implementation of arbitrarily rich displacement fields without the need of a-priori kinematic assumptions. The strong form of the principle of virtual displacements is used to obtain the equations of motion and the natural boundary conditions for beams in free vibration. An exact dynamic stiffness matrix is then developed by relating the amplitudes of harmonically varying loads to those of the responses. The resulting dynamic stiffness matrix is used with particular reference to the Wittrick-Williams algorithm to carry out free vibration analyses. According to the doublet lattice method, the natural mode shapes are subsequently used as generalized motions for the generation of the unsteady aerodynamic generalized forces. Finally, the g-method is used to conduct flutter analyses of both isotropic and laminated composite lifting surfaces. The obtained results perfectly match those from 1D and 2D finite elements and those from experimental analyses. It can be stated that refined beam models are compulsory to deal with the flutter analysis of wing models whereas classical and lower-order models (up to the second-order) are not able to detect those flutter conditions that are characterized by bending-torsion couplings.

• 신재생에너지
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• 제9권3호
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• pp.5-13
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• 2013

In the previous research, dynamic results have been analyzed in the time and frequency regions. Time and frequency region can be transformed by the Fourier transform. This transform is very useful about analyzing system behaviors. However, because of coupling, it cannot give clear results in the real system including lots of defects. In this paper, we introduced the analysis based on quefrency region to represent physical means clearly from complicated results. We simulated the drive train system which has defects, and compared between frequency and quefrency region to show its excellence. To do this process, We established mathematical model. The equation of motion was derived by the Lagrange equation and constraint equations. The constraint equation included relationships about gear mesh, flexibility of shaft. About numerical analysis, the Newmark beta method was used to get results. And FFT (Fast Fourier Transform) which converts results from time domain to frequency, qufrequency was used.

• Structural Engineering and Mechanics
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• 제73권2호
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• pp.209-223
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• 2020

This paper investigates the buckling behavior of carbon nanotube-reinforced composite plates supported by Kerr foundation model. In this foundation elastic of Kerr consisting of two spring layers interconnected by a shearing layer. The plates are reinforced by single-walled carbon nanotubes with four types of distributions of uniaxially aligned reinforcement material. The analytical equations are derived and the exact solutions for buckling analyses of such type's plates are obtained. The mathematical models provided, and the present solutions are numerically validated by comparison with some available results in the literature. Effect of various reinforced plates parameters such as aspect ratios, volume fraction, types of reinforcement, parameters constant factors of Kerr foundation and plate thickness on the buckling analyses of carbon nanotube-reinforced composite plates are studied and discussed.

• Structural Engineering and Mechanics
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• 제73권6호
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• pp.685-698
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• 2020

The dynamic stability of a functionally graded polymer microbeam reinforced by graphene oxides subjected to a periodic axial force is investigated. The microbeam is assumed to rest on an elastic substrate and is subjected to various immovable boundary restraints. The weight fraction of graphene oxides nanofillers is graded across the beam thickness. The effective Young's modulus of the functionally graded graphene oxides reinforced composite (FG-GORC) was determined using modified Halpin-Tsai model, with the mixture rule used to evaluate the effective Poisson's ratio and the mass density. An improved third order shear deformation theory (TSDT) is used in conjunction with the Chebyshev polynomial-based Ritz method to derive the Mathieu-Hill equations for dynamic stability of the FG-GORC microbeam, in which the scale effect is taken into account based on modified couple stress theory. Then, the Mathieu-Hill equation was solved using Bolotin's method to predict the principle unstable regions of the FG-GORC microbeams. The numerical results show the effects of the small scale, the graphene oxides nanofillers as well as the elastic substrate on the dynamic stability behaviors of the FG-GORC microbeams.

• Advances in aircraft and spacecraft science
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• 제5권1호
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• pp.51-71
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• 2018

This work proposes a theoretical and numerical study on the behavior of a tapered shaft rotor made of composite materials by the classical version h and the version p of the finite element method. Hierarchical form functions are used to define the model. The purpose of this paper is to determine the expressions of the kinetic and potential energies of the tree necessary for the results of the equations of motion. A comparison between the version h and the p version of the finite element method of the functions of polynomial and trigonometric hierarchical forms with six degrees of freedom per node, of a composite tapered and cylindrical shaft which rotates at a constant speed about its axis. It is found that when the number of functions of form (the version p) is increased, the solution converges. It is also observed that the conicity of the shaft increases the rigidity with respect to a uniform shaft having the same mechanical properties. The numerical simulation allowed us to determine the natural frequencies and the critical speeds of the composite shaft systems are compared with those available in the literature and the effectiveness of the methods used are discussed.

• Structural Engineering and Mechanics
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• 제67권5호
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• pp.465-479
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• 2018

In a previous study, design charts where proposed to help the torsional design of axially restricted reinforced concrete (RC) beams with squared cross section. In this article, new design charts are proposed to cover RC beams with rectangular cross section. The influence of the height to width ratio of the cross section on the behavior of RC beams under torsion is firstly shown by using theoretical and experimental results. Next, the effective torsional strength of a reference RC beam is computed for several values and combinations of the study variables, namely: height to width ratio of the cross section, concrete compressive strength, torsional reinforcement ratio and level of the axial restraint. To compute the torsional strength, the modified Variable Angle Truss Model for axially restricted RC beams is used. Then, an extensive parametric analysis based on multivariable and nonlinear correlation analysis is performed to obtain nonlinear regression equations which allow to build the new design charts. These charts allow to correct the torsional strength in order to consider the favourable influence of the compressive axial stress that arises from the axial restraint.

• 한국전산유체공학회지
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• 제16권1호
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• pp.53-59
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• 2011

In this study, steady and unsteady aerodynamic analyses of a huge rocket configuration have been conducted in a transonic flow region. The launch vehicle structural response are coupled with the transonic flow state transitions at the nose of the payload fairing. Before performing the coupled fluid-structure transonic aeroealstic simulations transonic aerodynamic characteristics are investigated for the pitching motions of the rocket at finite angle-of-attack. An unsteady CFD analysis method with a moving grid technique based on the Reynolds-averaged Navier-Stokes equations with the k-w SST transition turbulence model is applied to accurately predict the transonic loads of the rocket at pitching motion. It is shown that the fluctuating amplitude of the lateral aerodynamic loads imposed on the rocket due to the pitching motion can be significantly increased in the transonic flow region.