• Macromolecular Research
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• 제9권4호
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• pp.228-237
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• 2001

The evolution of conformational constraints in bisphenol-A polycarbonate (BAPC) upon quiescent bulk crystallization was quantitatively analyzed from calorimetric study employing a rigid amorphous fraction (RAF) as an indicator of the level of conformational constraints. From the correlation between corrected crystallinity (X$\sub$c/) and total rigid fraction (f$\sub$r/), it was found that, regardless of molar mass distribution and thermal treatment conditions, semicrystalline BAPC always exhibits greater f$\sub$r/ than X$\sub$c/ maintaining a quantitative relationship of f$\sub$r/〓2X$\sub$c/ in the range of 0.0 $\sub$c/< 0.4. This directly indicates the evolution of approximately the same amount of RAF as X$\sub$c/, (i.e., RAF〓X$\sub$c/) upon bulk crystallization of BAPC. It was also found that T$\sub$g/ per se and T$\sub$g/ broadening enhance as RAF increases, and there appears to be a critical level of RAF (>0.2) needed to initiate significant changes in both quantities.

• Asian-Australasian Journal of Animal Sciences
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• 제22권2호
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• pp.296-304
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• 2009

The nutritional significance of essential amino acids, as well as non-essential amino acids, is well documented in poultry production with regards to growth performance and protein accretion. However, the function of amino acids in the stress response is still unclear. L-Pipecolic acid, a L-lysine metabolite in the brain, induced a hypnotic and sedative effect acting via the ${\gamma}$- aminobutyric acid receptors. L-Arginine also induced a sedative effect via its metabolism to L-ornithine. In addition, three-carbon nonessential amino acids like L-alanine, L-serine and L-cysteine also induced sedative effects. These facts suggest that the requirement for amino acids in both essential and non-essential types may require reconsideration to add the concept of stress amelioration in the future.

• Journal of applied mathematics & informatics
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• 제12권1_2호
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• pp.233-241
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• 2003

The rolling schedule procedure has been an important part of the Enterprise Resource Planning (ERP) systems. The performance of production planning in an ERP system depends on the selection of the three parameters in rolling schedule procedure: frozen interval, replanning interval, and planning horizon (forecast window). This research investigated, in a theoretical approach, the combined impact of selections of those three parameters. The proven mathematical theorems provided guidance to re-duction of instability (nervousness) and to seek the optimal balance between stability and responsiveness of ERP systems. Further the theorems are extended to incorporate the cost structure.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1790-1800
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• 2006

Dynamic behavior of flexural-torsional coupled vibration of rotating beams using the Rayleigh-Ritz method with orthogonal polynomials as basis functions is studied. Performance of various orthogonal polynomials is compared to each other in terms of their efficiency and accuracy in determining the required natural frequencies. Orthogonal polynomials and functions studied in the present work are: Legendre, Chebyshev, integrated Legendre, modified Duncan polynomials, the special trigonometric functions used in conjunction with Hermite cubics, and beam characteristic orthogonal polynomials. A total of 5 cases of beam boundary conditions and rotation are studied for their natural frequencies. The obtained natural frequencies and mode shapes are compared to those available in various references and the results for coupled flexural-torsional vibrations are especially compared to both previously available references and with those obtained using NASTRAN finite element package. Among all the examined orthogonal functions, Legendre orthogonal polynomials are the most efficient in overall CPU time, mainly because of ease in performing the integration required for determining the stiffness and mass matrices.

• 한국수산과학회지
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• 제30권6호
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• pp.964-973
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• 1997

A tidal prism eutrophication model, an one-dimensional intertidal model, is developed to study water quality conditions at small coastal basins and tidal creeks. The model simulates the physical transport processes using the concept of tidal flushing. The concept is simple and straightforward, and thus is ideal for small coastal basins with complex geometry. The model, having twenty-four state variables in the water column, simulates salinity, temperature, dissolved oxygen, three algal groups, and the cycles of carbon, nitrogen, phosphorus and silica. The model is applied to the Lynnhaven Bay, a small coastal basin of Chesapeake Bay in U.S.A. The model is calibrated using the field data collected in 1994, and then is verified using the independently collected data in 1980. The model overall gives a good reproduction of the field data, partly owing to the data collected from the field surveys specifically designed for the model application. This paper presents the procedure, and the results of the model calibration and verification.

• Computers and Concrete
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• 제17권4호
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• pp.523-539
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• 2016

Alkali-activated binder (AAB) is increasingly being considered as an eco-friendly and sustainable alternative to portland cement (PC). The present study evaluates 30 different AAB mixtures containing fly ash and/or slag activated by sodium hydroxide and sodium silicate by correlating their properties from micro to specimen level using regression. A model is developed to predict compressive strength of AAB as a function of volume fractions of microstructural phases (physicochemical properties) and ultrasonic pulse velocity (elastic properties and density). The predicted models are ranked and then compared with the experimental data. The correlations were found to be quite reasonable (R2 = 0.89) for all the mixtures tested and can be used to estimate the compressive strengths for similar AAB mixtures.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제22권3호
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• pp.175-201
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• 2019

Spending as much time outside of school as in school, gifted youth are affected by non-school aspects including parents, other family members, peers, mentors, mathematics competitions and camp participations. These influences have been known to shape children's intellectual development, academic achievement, interests, and eventually college and career choices. From interviews with five former Olympians from Korea to identify out-of-school influences on their academic achievement and development, we discovered, in addition to confirmation of previously identified factors, additional sources of positive influence seldom previously mentioned and more common to Korean culture were gleaned - mathematics workbooks and Ha-Gwon. The findings of this study are informative for teachers and parents who are interested in development of gifted youth in providing ways to accommodate their special needs and in showing how they can carefully individualize those sources to be positively affecting intellectual development as well as academic achievement.

• 한국의류산업학회지
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• 제3권5호
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• pp.455-465
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• 2001

Assessing soil removal is of interest to the washing machine industry because of government-mandated energy savings and changes in detergent formulation and consumer laundry practices. We designed this study to examine the laundry process from a holistic perspective by integrating factors perceived to be of importance. Our purpose was to assess the impact of selected variables (fabric and soil type, wash temperature and time. detergent amount, and degree of agitation) on soil removal using accelerated laundry conditions. We used the Taguchi method to develop the research design and ANOVA to analyze the data. Although soil removal was affected by fabric type, soil type, type and amount of detergent, degree of agitation, wash time and temperature, and water hardness and volume, wash temperature was the most significant variable.

• Journal of applied mathematics & informatics
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• 제28권1_2호
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• pp.351-361
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• 2010

The solution of large sparse linear systems is one of the most important problems in large scale scientific computing. Among the many methods developed, the preconditioned Krylov subspace methods are considered the preferred methods. Selecting a suitable preconditioner with appropriate parameters for a specific sparse linear system presents a challenging task for many application scientists and engineers who have little knowledge of preconditioned iterative methods. The prediction of ILU type preconditioners was considered in [27] where support vector machine(SVM), as a data mining technique, is used to classify large sparse linear systems and predict best preconditioners. In this paper, we apply the data mining approach to the sparse approximate inverse(SAI) type preconditioners to find some parameters with which the preconditioned Krylov subspace method on the linear systems shows best performance.

• 농촌계획
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• 제6권2호
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• pp.12-19
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• 2000

Irrigation pipeline networks consist mainly of buried pipes and are therefore relatively free from topographic constraints. Installation of irrigation pipeline systems is increasing since the systems have several advantages compared to open channel systems. To achieve economic design of pipeline networks, the layout should meet several conditions such as shortest path, maximum flow, and least cost. Graph theory is mathematical tool which enable to find out optimum layout for complicated network systems. In this study, applicability of graph theory to figure out optimum layout of irrigation pipeline networks was evaluated.