• Steel and Composite Structures
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• 제29권6호
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• pp.749-758
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• 2018

This article derived a hybrid coupling technique using the higher-order displacement polynomial and three soft computing techniques (teaching learning-based optimization, particle swarm optimization, and artificial bee colony) to predict the optimal stacking sequence of the layered structure and the corresponding frequency values. The higher-order displacement kinematics is adopted for the mathematical model derivation considering the necessary stress and stain continuity and the elimination of shear correction factor. A nine noded isoparametric Lagrangian element (eighty-one degrees of freedom at each node) is engaged for the discretisation and the desired model equation derived via the classical Hamilton's principle. Subsequently, three soft computing techniques are employed to predict the maximum natural frequency values corresponding to their optimum layer sequences via a suitable home-made computer code. The finite element convergence rate including the optimal solution stability is established through the iterative solutions. Further, the predicted optimal stacking sequence including the accuracy of the frequency values are verified with adequate comparison studies. Lastly, the derived hybrid models are explored further to by solving different numerical examples for the combined structural parameters (length to width ratio, length to thickness ratio and orthotropicity on frequency and layer-sequence) and the implicit behavior discuss in details.

• Advances in nano research
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• 제10권3호
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• pp.271-280
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• 2021

The present work deals with an investigation on longitudinal wave propagation in nanobeams made of graphene sheets, for the first time. The nanobeam is modelled via a higher-order shear deformation theory accounts for both higher-order and thickness stretching terms. The general nonlocal strain gradient theory including nonlocality and strain gradient characteristics of size-dependency in order is used to examine the small-scale effects. This model has three-small scale coefficients in which two of them are for nonlocality and one of them applied for gradient effects. Hamilton supposition is applied to obtain the governing motion equation which is solved using a harmonic solution procedure. It is indicated that the longitudinal wave characteristics of the nanobeams are significantly influenced by the nonlocal parameters and strain gradient parameter. It is shown that higher nonlocal parameter is more efficient than lower nonlocal parameter to change longitudinal phase velocities, while the strain gradient parameter is the determining factor for their efficiency on the results.

• 한국자원식물학회지
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• 제11권3호
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• pp.272-278
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• 1998

This study was carried out to investigate the functional properties such as nitrogen solubility, emulsifying property , foaming capapcity , water and oil absorption of Camellia (Camellia japonica .) seed protein isolate in condition of distilled water and 0.5M NaCl solution at pH 2.0∼10.0. Nitrogen solubility of Camellia protein isolate in distilled water showed the minimum value at pH 4.0 and increased at pH lower or higher than the isoelectric point(pH 4.0). It was 90.0 %at pH 10.0 Nitrogen solubility of 0.5M NaCl solution showed a similar pattern with that of distrille dwater but was higher than that of distilled water except pH 2.0 and pH 10.0. Emulsifying activity of Camellia seed protein islate showed the minimum value at pH 4.0, but was higher at ether value of pH. Emulsifying stability of protein isolate was stable by heat treatment for 30min, at 80℃ and increased in 0.5M NaCl solution more than that of distille dwater. Foaming capacity of Camellia seed protein isolate in distill3ed water showed the minimum value near the isoelectric point, While it changed little at other values of pH. Foaming stability slowly decreased as, but didn't make a significant difference as time was delayed . Oil absorption was 1.4ml per a sample of 1g and water absorption was 0.9ml per a sample of 1g. The former was higher than the latter . The content of total amino acid of Camellia protein isolate was 43.67% and the major total amino acid of Camellia protein isolate was 43.67% and the major total amino acid was in the order of glutamic acid , arginine, aspartic acid, and leucine.

• 대한토목학회논문집
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• 제2권3호
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• pp.75-86
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• 1982

본 연구에서는 3절점, 6자유도를 갖는, 종래의 Timoshenko 보 이론에 근거한 깊은 보(Thick beam) 요소(DB6)와 3절점, 7자유도를 갖는 3차 축방향변위를 가정한 고차 보 요소(DB7)의 3차원 연속체로부터의 Degeneration을 보여 주고 있다. DB6 보 요소는 전단변형률의 비살제적인 선형분포를 보완하기 위하여 전단계수(shear coefficient)를 도입하고 있는 반면 고차 DB7 보 요소는 보다 실제적인 전단변형률의 2차분포를 가정하고 있다. 이 들 두 보 요소를 이용하여 계산된 해(解)는 Timoshenko 방정식의 해(解), 얕은 보(Thin beam)의 해(解) 및 다른 여러 보 요소들의 해(解)와 비교된다. 본 연구의 결과는 고차 DB7 보 요소가 보의 정력화적 해석이나 자유진동 해석에 있어서 다른 보 요소들에 비해 월등히 정확함을 보여주고 있다.

• Food Science and Biotechnology
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• 제16권5호
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• pp.722-727
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• 2007

Mucilage containing ${\gamma}-polyglutamic$ acid (PGA) was efficiently generated by the solid-state fermentation (SSF) of soybean grit by Bacillus firmus NA-1. B. firmus NA-1 was shown to be a glutamate-dependent strain for PGA production. The SSF of soybean grit was optimized in order to produce mucilage with a fortification of 5% glutamate, resulting in higher levels of mucilage production (6.14%) and a higher consistency index ($1.1\;Pa\;sec^n$). The sticky mucilage was comprised of 38% PGA, 7% levan, and some biopolymers. With regard to the viscoelastic properties of the mucilage solution, the viscous modulus (G") obtained from soybean grit fortified with 5% glutamate was approximately 64 times higher titan that of the mucilage solution obtained without glutamate. Although the addition of glutamate in the SSF of soybean grit influenced the rate of PGA production, the molecular weight of PGA remained unaltered, and was detected in a range between 1,400-1,440 kDa.

• International Journal of Industrial Entomology and Biomaterials
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• 제26권2호
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• pp.113-118
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• 2013

In this study, silk sericin films were prepared using different extraction methods, and the molecular conformation of sericin was examined using Fourier-transform infrared spectroscopy with attenuated total reflection geometry. Additionally, the effect of the film side (air-facing side or plate-facing side) on the molecular conformation of the sericin films was investigated. Interestingly, the molecular conformation of the sericin film depended on the film side. The molecular conformation of air-facing side of the sericin film was significantly influenced by extraction solution and time. The ${\beta}$-sheet crystallization and the crystallinity index of the sericin film markedly increased with an increase in the extraction time in hot water. The order of the crystallinity indices for the sericin films obtained with different extraction solutions was as follows: citric acid solution > urea solution >> hot water. In contrast, no remarkable differences were observed in the molecular conformation of the plate-facing side of the sericin film after extraction in hot water for different time periods. Urea and citric acid solution extractions showed remarkably higher crystallinity indices for sericin than those obtained after hot water extraction. However, no significant differences were observed in the crystallinity index of sericin between urea and citric acid solution extraction in plate-facing side of the film.

• 한국환경과학회지
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• 제21권4호
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• pp.479-488
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• 2012

A Dielectric barrier discharge (DBD) plasma is shown in the present investigation to be effective of phenol degradation in the aqueous solutions in batch reactor with continuous air bubbling. Removal of phenol and effects of various parameters on the removal efficiency in the aqueous solution with high-voltage streamer discharge plasma are studied. The effect of 1st voltage (80 ~ 220 V), air flow rate (3 ~ 7 L/min), pH (3 ~ 11), electric conductivity of solution (4.16 ${\mu}S$/cm, deionized water) ~ 16.57 mS/cm (addition of NaCl 10 g/L) and initial phenol concentration (2.5 ~ 20.0 mg/L) were investigated. The observed results showed that phenol degradation was higher in the basic solution than that of the acidic. The optimum values on the 1st voltage and air flow rate for phenol degradation were 140 V and 6 L/min, respectively. It was considered that absorbance variation of $UV_{254}$ of phenol solution can be use as an indirect indicator of change of the non-biodegradable organic compounds within the treated phenol solution. Electric conductivity was not influenced the phenol degradation. To obtain the removal efficiency of phenol and COD of phenol over 97 % (initial phenol concentration, 10.0 mg/L), 80 min and 120 min were need, respectively. Phenol and COD degradation showed a pseudo-first order kinetics.

• 대한기계학회논문집B
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• 제24권3호
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• pp.426-434
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• 2000

This paper deals with a generalized similarity solution for the one-dimensional solidification of ternary or higher-order multicomponent alloys. The present approach not only retains the existing features of binary systems such as temperature- solute coupling, shrinkage-induced flow, solid-liquid property differences, and finite back diffusion, but also is capable of handling a multicomponent alloy without restrictions on the partition coefficient and microsegregation parameter. For an alloy of N-solute species, governing equations in the mushy region reduce to (N+2) nonlinear ordinary differential equations via similarity transformation, which are to be solved along with the closed-form solutions for the solid and liquid regions. A linearized correction scheme adopted in the solution procedure facilitates to determine the solidus and liquidus positions stably. The result for a sample ternary alloy agrees excellently with the numerical prediction as well as the reported similarity solution. Additional calculations are also presented to show the utility of this study. Finally, it is concluded that the present analysis includes the previous analytical approaches as subsets.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.168-174
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• 2010

In this research, an effective method for reducing the fibrillation of lyocell fibers, which are spun from a solution of cellulose in N-methyl morpholine-N-oxide(NMMO), through consecutive chemical treatments. Undried solution-spun cellulosic fiber was firstly treated with 10 to 30 wt% of multifunctional crosslinking agents, such as ethylene glycol poly(3-chloro-2-hydroxypropyl) ether, and then dipped into alkaline solution to introduce epoxy functions. Finally steam condition was applied to occur a chemical crosslinking in order to reduce the fibrillation on the surface of fibers. Fibrillation was also reduced significantly by adding extra $Na_2SO_4$ in NaOH solution. In addition, Antifibrilllated lyocell fibers show the slightly higher dyeability(4 %) to Cibacron Blue without serious reduction of mechanical properties.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제23권4호
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• pp.301-327
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• 2019

The proper orthogonal decomposition (POD) method for time-dependent problems significantly reduces the computational time as it reduces the original problem to the lower dimensional space. Even a higher degree of reduction can be reached if the solution is smooth in space and time. However, if the solution is discontinuous and the discontinuity is parameterized e.g. with time, the POD approximations are not accurate in the reduced space due to the lack of ability to represent the discontinuous solution as a finite linear combination of smooth bases. In this paper, we propose to post-process the sample solutions and re-initialize the POD approximations to deal with discontinuous solutions and provide accurate approximations while the computational time is reduced. For the post-processing, we use the Gegenbauer reconstruction method. Then we regularize the Gegenbauer reconstruction for the construction of POD bases. With the constructed POD bases, we solve the given PDE in the reduced space. For the POD approximation, we re-initialize the POD solution so that the post-processed sample solution is used as the initial condition at each sampling time. As a proof-of-concept, we solve both one-dimensional linear and nonlinear hyperbolic problems. The numerical results show that the proposed method is efficient and accurate.