• Advances in aircraft and spacecraft science
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• v.6 no.1
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• pp.51-67
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• 2019

AMOSC (Automatic Margin Of Safety Calculation) is a SW tool which has been developed to calculate the failure index of layered composite structures by referring to the cutting edge state-of-the-art LaRC05 criterion. The stress field is calculated by a finite element code. AMOSC allows the user to calculate the failure index also by referring to the classical Hoffman criterion (which is commonly applied in the aerospace industry). When developing the code, particular care was devoted to the computational efficiency of the code and to the automatic reporting capability. The tool implemented is an API which has been embedded into Femap Siemens SW custom tools. Then, a user friendly graphical interface has been associated to the API. A number of study-cases have been solved to validate the code and they are illustrated through this work. Moreover, for the same structure, the differences in results produced by passing from Hoffman to LaRC05 criterion have been identified and discussed. A number of additional comparisons have thus been produced between the results obtained by applying the above two criteria. Possible future developments could explore the sensitivity of the failure indexes to a more accurate stress field inputs (e.g. by employing finite elements formulated on the basis of higher order/hierarchical kinematic theories).

• Computers and Concrete
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• v.23 no.4
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• pp.281-294
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• 2019

The post-fire behavior of structural elements and the cooling process has always been one of the main concerns of the structural engineers. The structures can be cooled at different rates, where they affect the structure's behavior. In the present study, a numerical model has been developed using the Abaqus program to investigate the effect of cooling rate on the post-fire behavior of the CFST column. To verify the model, results of an experimental study performed on CFST columns within a full heating and cooling cycle have been used. In this model, coMParison of the residual strength has been employed in order to examine the behavior of CFST column under different cooling rates. Furthermore, a parametric study was carried out on the strength of steel and concrete, the height of the specimens, the axial load ratio and the cross-sectional shape of the specimen through the proposed model. It was observed that the cooling rate affects the behavior of the column after the fire, and thus the higher the specimen's temperature is, the more effect it has on the behavior. It was also noticed that water cooling had slightly more residual strength than natural cooling. Furthermore, it was recognized from the parametric study, that by increasing the strength of steel and concrete and the load ratio, as well as modifying the cross-sectional shape from circular to square, residual strength of column at the cooling phase was less than that of the heating phase. In addition, with reducing column height, no change was witnessed in the column behavior after the cooling phase.

• Analytical Science and Technology
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• v.32 no.5
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• pp.210-216
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• 2019

Concentrations of Cu, Zn, Fe, Mn, Ni and Cr have been estimated in sediments of the Shitalakhya River at Polash-Ghorashal area, Narsingdi, Bangladesh. 36 samples of sediments from nine sampling point at different locations of Shitalakhya River were collected to determine the concentration of Cu, Zn, Fe, Mn, Ni, Cr and the samples were analyzed by atomic absorption spectrophotometer (AAS). The obtained results were compared with national and international guidelines. The levels of heavy metal concentrations in sediments were found to decrease in the order of Fe > Mn > Zn > Ni > Cu > Cr, respectively. The heavy metal concentration in sediment of Shitalakhya was below the recommended safe limits of heavy metals by WHO, FAO and other international standards. Contamination factor (CF) of Zn and Cu at sampling point Fsd2 show higher (> 1) values due to the influence of external discrete sources like wastage catalysts of ZnO and CuO. Geo-accumulation index values of the study indicate as non-contaminated to moderately contaminate.

• Advances in nano research
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• v.11 no.6
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• pp.621-640
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• 2021

Effect of thickness stretching on mechanical behavior of functionally graded (FG) carbon nanotubes reinforced composite (CNTRC) laminated nanoplates resting on elastic foundation is analyzed in this paper using a novel quasi 3D higher-order shear deformation theory. The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Single-walled carbon nanotubes (SWCNTs) are the reinforced elements and are distributed with four power-law functions which are, uniform distribution, V-distribution, O-distribution and X-distribution. To cover various boundary conditions, an analytical solution is developed based on Galerkin method to solve the governing equilibrium equations by considering the nonlocal strain gradient theory. A modified two-dimensional variable Winkler elastic foundation is proposed in this study for the first time. A parametric study is executed to determine the influence of the reinforcement patterns, power-law index, nonlocal parameter, length scale parameter, thickness and aspect ratios, elastic foundation, thermal environments, and various boundary conditions on stresses, displacements, buckling loads and frequencies of the CNTRC laminated nanoplate.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.13 no.2
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• pp.10-15
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• 1984

The aims of this study are to obtain a suitable method and a proper mesh for investigation of the temperature distribution and heat transfer. The relative errors of temperature distribution and heat transfer for each mesh are acquired in accordance with linear finite element (FEM 3), square finite element (FEM 6), cubic finite element (FEM 10), and finite difference method (FDM). It has been found that FEM 10 is the most accurate measure to obtain the temperature distribution and heat transfer. However, no significant results have been obtained successfully, because when higher order finite element methods are used the more computational efforts are necessary due to the distribution of elements. The results of this study are as follows ; 1 . In case of a=b=L, meshes for less than $1\%$ relative errors (temperature distribution) acquired in various methods to exact solution are $2\times2,\;4\times4,\;8\times8\;and\;8\tiems8$ for each FEM 10, FEM 6, FEM 3 and FDM and a=L, b=1/2L are $10\times5$ for each FEM 3 and FDM. And the tendency of results acquired of heat transfer is similar to those above. 2 . In computational efforts (a=b=L), FEM 6 has taken 21 times. and FEM 10 154times FEM 3 and FDM and FEM 3 is the sane as FDM.

• Journal of Korean Port Research
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• v.8 no.2
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• pp.37-56
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• 1994

The effects of wave energy focusing by a submerged berm type of structure is examined. The fundamental idea is based on the phenomenon of refraction by a lens-shaped crescent structure which results in the focusing of wave energy on the center line of the structure. The shape of the submerged structure is a complex curve combining circular with elliptical elements. Based on the design procedure, a special configuration of structure(termed herein as a triple crescent structure) is introduced. Next, some hydraulic model tests are performed to confirm the wave focusing effect in laboratory. In addition, in order to interpret the wave focusing performance behind the structure, a numerical procedure by the hybrid element method is used on the basis of the conventional mild slope equation but modified and extended to allow for steeper bottom slopes and higher curvature. The modified refraction and diffraction provide additional mechanism for wave height amplification and the maximum amplification for triple crescent structure is presented. It also allows for the possibility of wave energy scattering with the change of the incident wave direction. Comparisons with previous theoretical results involving a submerged crescent shape structure are described.

• Advances in materials Research
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• v.11 no.2
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• pp.91-109
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• 2022

This paper presents a closed-form higher-order analysis of interfacial shear stresses in RC continuous beams strengthened with bonded prestressed laminates. For retrofitting reinforced concrete continuous beams is to bond fiber reinforced prestressed composite plates to their tensile faces. An important failure mode of such plated beams is the debonding of the composite plates from the concrete due to high level of stress concentration in the adhesive at the ends of the composite plate. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the RC continuous beams strengthened with bonded prestressed laminates. The theoretical predictions are compared with other existing solutions. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as laminate stiffness and the thickness of the laminate where all were found to have a marked effect on the magnitude of maximum shear and normal stress in the composite member.

• International Journal of Computer Science & Network Security
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• v.22 no.1
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• pp.113-120
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• 2022

Information technologies in higher education are the basis for solving the tasks set by monitoring the quality of higher education. The directions of aplying information technologies which are used the most nowadays have been listed. The issues that should be addressed by monitoring the quality of higher education with the use of information technology have been listed. The functional basis for building a monitoring system is the cyclical stages: Observation; Orientation; Decision; Action. The monitoring system's considered cyclicity ensures that the concept of independent functioning of the monitoring system's subsystems is implemented.. It also ensures real-time task execution and information availability for all levels of the system's hierarchy of vertical and horizontal links, with the ability to restrict access. The educational branch uses information and computer technologies to monitor research results, which are realized in: scientific, reference, and educational output; electronic resources; state standards of education; analytical materials; materials for state reports; expert inferences on current issues of education and science; normative legal documents; state and sectoral programs; conference recommendations; informational, bibliographic, abstract, review publications; digests. The quality of Ukrainian scientists' scientific work is measured using a variety of bibliographic markers. The most common is the citation index. In order to carry out high-quality systematization of information and computer monitoring technologies, the classification has been carried out on the basis of certain features: (processual support for implementation by publishing, distributing and using the results of research work). The advantages and disadvantages of using web-based resources and services as information technology tools have been discussed. A set of indicators disclosed in the article evaluates the effectiveness of any means or method of observation and control over the object of monitoring. The use of information technology for monitoring and evaluating higher education is feasible and widespread in Ukrainian education, and it encourages the adoption of e-learning. The functional elements that stand out in the information-analytical monitoring system have been disclosed.

• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.107-117
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• 2007

Dispersion characteristics and envirounmental impactes of the stream sediments were investigated and geochemical disaster in the Namhae-Hwagye area was predicted. Stream sediments having no possibility of contamination effect and representing drainage basins were collected. Major and hazardous elements concentrations were determined by XRF, ICP-AES and NAA analysis methods. Acid decomposition for the ICP-AES have been used $HClO_4$ and HF with $200^{\circ}C$ heating at 1'st and after that $HClO_4$, HF and HCl with $200^{\circ}C$ heating at 2'nd stage. Hazardous elements concentrations for the stream sediments in the Namhae area were Cu $5.66{\sim}168\;ppm$, Pb $18.0{\sim}40.7\;ppm$, Cr $21.6{\sim}147\;ppm$, Co $4.86{\sim}25.3\;ppm$. Hazardous elements concentrations for the stream sediments in the Hwagye area were Cu $16.4{\sim}41.2\;ppm$, Pb $26.5{\sim}37.5\;ppm$ Cr $79.6{\sim}153\;ppm$, Co $15.7{\sim}29.5\;ppm$. Concentration of Cu and Co in the stream sediments show a negative correlation with $SiO_2$ in all study area. According to E.I.(Enrichment Index) of stream sediments was not enriched in study area. And average E.I. was 0.35 (Namhae) and 0.56 (Hwagye) respectively. The stream sediments were enriched as in order of Pb > Cr > Co > Cu. And the average of Enrichment Factor (E.F.) was 0.46 to 2.84, respectively. E.F. concentration of Cu and Co were nearly similar enrichment characteristic but E.F. concentration of Cr were higher enrichnent characteristic in Namhae than Hwagye area. Pb was highly enriched in all study area but the tolerable level that used to investigate the enrichment degree of hazardous elements, was not exposed to harmful hazardous elements.

• Korean Journal of Health Education and Promotion
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• v.19 no.2
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• pp.23-43
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• 2002

Purpose: The purpose of this study is to examine and analyse factors related to the actual status and practice of breast-feeding during an infant period to grasp elements detrimental to breast-feeding and, therefore, provide basic information useful for its effective practice and encouragement. Method: From April 1 to June 30, 2001, this study was carried out with the mothers of 337 who were 6 months old, as of the surveyed date, of infants born in 2002 and registered in Seongju-gun Public Health Center, Gyeongsangbug-do Province. The method for its survey included both of the visiting and telephone interviews, and questions were mainly about the mothers' general characteristics(3 questions), infants' general characteristics(3 questions), environmental characteristics of infant delivery( 4 questions), support to breast-feeding(4 questions), understanding of breast-feeding(5 questions), and feeding type during the 1 to 6-month period after birth. Result: 1. The feeding type during the I-month period after birth showed that the breast-feeding accounted for 42.4%, which was higher than dry milk-feeding(30%) or mixed milk-feeding(26.8%). However, it began to be lower than the dry milk-feeding from the 2-month period after birth. During the 6-month period, the breast-feeding accounted for 28.6% which was lower than 56.5% of the dry milk-feeding. 2. The mothers who were encouraged by their delivery clinic to and were educated to breast-feed infants accounted for 55.4% and 41.4%, respectively, which were relatively low. The understanding of breast-feeding indicated that the responses were positive from the view point of mother ＆ infant health, but negative from mother's physical form. 3. It was shown that the lower the educational background of mother(p〈0.05) and the higher the unemployment of mother(p〈0.001), the higher the positive understanding of breast-feeding, and that the higher the entire support to breast-feeding, the more positive their understanding. 4. It was also shown that the lower the educational background of mother(p〈0.05), the higher the unemployment of mother(p〈0.001), the more the experience in breast-feeding at a delivery clinic(p〈0.01) and the faster the initial feeding(p〈0.001), the higher the rate of breast-feeding. 5. The factor having an effect on breast-feeding included a delivery clinic's encouragement to breast-feed(p〈0.001), understanding of breast-feeding(p〈0.01), father's comment on feeding method(p〈0.05) and mother's employment(p〈0.05). Discussion: In order to encourage the breast-feeding, as shown above, it is required, fist of all, to offer pregnant women an education about importance and excellence of breast-feeding and its appropriate method before delivery in advance to result in a positive comprehension of the breast-feeding. To do that, both the publicity activities and program development designed to encourage the breast-feeding must be performed in advance at the government level. In addition to that, the mother-infant space as ‘rooming-in’ available for breast-feeding immediately after delivery must be prepared on the basis of legal and administrative support. Finally, female employees' leave after childbirth must be performed for the purpose of productive welfare and circumstances also be prepared for breast-feeding, such as a children's home at work.