• Title/Summary/Keyword: Behavior pattern

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Elastic stability of functionally graded graphene reinforced porous nanocomposite beams using two variables shear deformation

  • Fortas, Lahcene;Messai, Abderraouf;Merzouki, Tarek;Houari, Mohammed Sid Ahmed
    • Steel and Composite Structures
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    • v.43 no.1
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    • pp.31-54
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    • 2022
  • This paper is concerned with the buckling behavior of functionally graded graphene reinforced porous nanocomposite beams based on the finite element method (FEM) using two variables trigonometric shear deformation theory. Both Young's modulus and material density of the FGP beam element are simultaneously considered as grading through the thickness of the beam. The finite element approach is developed using a nonlocal strain gradient theory. The governing equations derived here are solved introducing a 3-nodes beam element, and then the critical buckling load is calculated with different porosity distributions and GPL dispersion patterns. After a convergence and validation study to verify the accuracy of the present model, a comprehensive parametric study is carried out, with a particular focus on the effects of weight fraction, distribution pattern of GPL reinforcements on the Buckling behavior of the nanocomposite beam. The effects of various structural parameters such as the dispersion patterns for the graphene and porosity, thickness ratio, boundary conditions, and nonlocal and strain gradient parameters are brought out. The results indicate that porosity distribution and GPL pattern have significant effects on the response of the nanocomposite beams, and the results allows to identify the most effective way to achieve improved buckling behavior of the porous nanocomposite beam.

Finite Element Analysis of Nano Deformation for the Hyper-Fine Pattern Fabrication by using Nanoindentation (나노인덴테이션을 이용하여 극미세 패턴을 제작하기 위한 나노 변형의 유한요소해석(I))

  • 이정우;윤성원;강충길
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.5
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    • pp.210-217
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    • 2003
  • In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation was studied with numerical method by ABAQUS S/W. Polymer (PMMA) and brittle materials (Si, Pyrex glass) were used as specimens, and forming conditions to reduce the elastic restoration and pile-up was proposed. The indenter was modeled a rigid surface. Minimum mesh sizes of specimens are 1-l0mm. The result of the investigation will be applied to the fabrication of the hyper-fine pattern and mold.

Friction Behavior of Micro-scale Groove Surface Patterns Under Lubricated Sliding Contact

  • Chae Young-Hun
    • KSTLE International Journal
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    • v.6 no.2
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    • pp.51-57
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    • 2005
  • Surface texturing of tribological applications is an attractive technology of engineered surface. Therefore, reduction of friction is considered to be necessary for improved efficiency of machines. The current study investigated the potential of textured micro-scale grooves on bearing steel flat mated with pin-on-disk. We discuss reducing friction due to the influence of sliding direction at surface pattern. We can indicate lubrication mechanism as a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for the lubrication condition. It was found that the friction coefficient was changed by the surface pattern and sliding direction, even when surface pattern was the same. It was thus verified that micro-scale grooves could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions. The lubrication regime influences the friction coefficient induced by the sliding direction of groove pattern. The friction coefficient depends on a combination of resistance force and hydrodynamic.

Finite Element Analysis of Nano Deformation for Hyper-fine Pattern Fabrication by Application of Nano-scratch Process (나노스크래치 공정을 이용하여 극미세 패턴을 제작하기 위한 나노 변형의 유한요소해석)

  • 이정우;강충길;윤성원
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.3
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    • pp.139-146
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    • 2004
  • In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation scratch test was studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass 7740) were used as specimens, and forming conditions to reduce the elastic recovery and pile-up were proposed. The indenter was modeled as a rigid surface. Minimum mesh sizes of specimens are 1-l0nm. Variables of the nanoindentation scratch test analysis are scratching speed, scratching load, tip radius and tip geometry. The nano-indentation scratch tests were performed by using the Berkovich pyramidal diamond indenter. Comparison between the experimental data and numerical result demonstrated that the FEM approach can be a good model of the nanoindentation scratch test. The result of the investigation will be applied to the fabrication of the hyper-fine pattern.

An Adaption of Pattern Sequence-based Electricity Load Forecasting with Match Filtering

  • Chu, Fazheng;Jung, Sung-Hwan
    • Journal of Korea Multimedia Society
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    • v.20 no.5
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    • pp.800-807
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    • 2017
  • The Pattern Sequence-based Forecasting (PSF) is an approach to forecast the behavior of time series based on similar pattern sequences. The innovation of PSF method is to convert the load time series into a label sequence by clustering technique in order to lighten computational burden. However, it brings about a new problem in determining the number of clusters and it is subject to insufficient similar days occasionally. In this paper we proposed an adaption of the PSF method, which introduces a new clustering index to determine the number of clusters and imposes a threshold to solve the problem caused by insufficient similar days. Our experiments showed that the proposed method reduced the mean absolute percentage error (MAPE) about 15%, compared to the PSF method.

Research on Tribology Characteristics Using DLC Thin Film and Lithography Processes (DLC 박막 및 리소그래피 공정을 적용한 트라이볼러지 특성 연구)

  • T.H. Jang;J.H. Park;T.G. Kim
    • Journal of the Korean Society for Heat Treatment
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    • v.36 no.6
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    • pp.412-421
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    • 2023
  • As the demand for mechatronic systems and high performance increases in the machinery industry, the importance of improving friction characteristics is emphasized. During relative movement of objects, friction and wear occur on two surfaces in contact, and various methods are being designed to increase the lifespan and energy efficiency of machines. The energy increase effect using lubricants is a well-known method. In this study, a micro-sized rectangular grid pattern was produced by applying a precise micro-pattern photo lithography process. Rectangular grid patterns of the same shape and friction behavior according to the size of the pattern were produced in convex and concave shapes, and the tribological characteristics of each were analyzed.

A Study on the mother's attribution and behavioral reaction to behavior problem of child. (아동의 문제행동에 대한 어머니의 귀인과 행동반응의 관계)

  • 이은희
    • Journal of the Korean Home Economics Association
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    • v.34 no.2
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    • pp.31-42
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    • 1996
  • The purpose of this study was to examine the mother's perception on the concrete pattern of such behavior problems as noncompliance, jealousy, dependency, hyperactivity and stealing, by analyzing the difference between two cases of her own child and another mother's child relating to her attribution to the behavior problem of the child and the relationship between her attribution and behavioral reaction. This study was carried out by using 515 questionnaires answered by 1000 mothers of children of 7 kindergartens in Ulsan and Taegu, using Melissa Sweitzer's method (1986). The data was subjected to t-test, Pearson's correlation coefficient. T-test was applied to test the difference between two cases of her own child and another mother's child relating to her attribution to the behavior problem of the child and Person's correlation coefficient was estimated to test the relationship between her attribution and behavioral reaction. The result of this study is sumarized as follows : 1. It was shown that the mother's attribution to the behavior problem of the child is less serious when her child showed the behavior problem than when another child dose the problem while her attribution has an affective reaction to the behavior problem of the child. 2. The relationship between the mother's attribution and behavior reaction to the behavior problem of the child appeared variously in accordance with the attribution factor and behavior problem. Then the mother showed more attribution to stability while frequently ignoring the child.

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A Study on Sexual Function of Women with Coronary Artery Disease (관상동맥질환 여성의 성기능에 관한 연구)

  • Kim, Choon Shim;So, Hyang Sook
    • Korean Journal of Adult Nursing
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    • v.12 no.1
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    • pp.99-111
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    • 2000
  • The purpose of this study was to identify risk factors related to sexual function of women with coronary artery disease, and to determine the predictors of sexual function. The study design, a descriptive correlational study, was done through structural questionnaire and interview. A total of 50 subjects from C University Hospital at Kwang-ju city who have undergone coronary angiography at department of cardiology were observed and interviewed from Feb. 22, 1999 to March. 23, 1999. The number of affected vessels, the level of total serum cholesterol, and the ejection fraction of 2-D echo cardiography were analyzed to evaluate the severity of coronary artery disease. And also type A behavior pattern, health behavior, Brief Index of Sexual Functioning for Women (BISF-W) were measured. The data obtained were analyzed using percentage, mean and standard deviation, t-test, ANOVA, Pearson's correlation coefficient, and stepwise multiple regression analysis via SPSS PC+. The results of this study were as follows: 1. The mean age of the subjects were 58.1 and 72.0% of those have been married over 30 years. Seventy two percentage were unemployed and monthly family income of 56.6% was less than 1,000,000 won (approximately $ 840). Eighty percent were in their postmenopausal state, and the frequency of sexual intercourse of 84.0% were two to three times per month. 2. The scores of type A behavior pattern were from 16 to 38(mean 24.94) and health behavior ranged from 21 to 43(mean 31.2). Abstinence from smoking, alcohol, and caffeine were best compliant factors and weight control and exercise were least abided ones. The result of 2D-ECHO EF showed that the half of the subjects were abnormal, and 24% had more than 240mg/dl of total serum cholesterol. The coronary angiography showed that 64% of the subjects had more than one affected vessels. 3. The predictors to explain the factor score of 'orgasm' were number of health examination, the pre- or post-menopausal state, protestant, number of coronary vessel affected, level of serum total cholesterol, and comorbid group of hypertension and diabetes, and it's total variance accounted for 52.4%. The predictors to explain the factor score of 'sexual activity' were comorbid group of hypertension and diabetes and type A behavior pattern, which accounted for 22.4% of total variance. The predictors to explain the factor score of 'sexual satisfaction' were type A behavior pattern, no religion, exercise, level of serum total cholesterol, and pre or post menopausal state, which accounted for 52.1%. The predictors to explain the factor score of 'sexual desire' were the period of marriage, type A behavior, employment or unemployment, and weight control, which accounted for 43.2%. The predictors to explain the factor score of 'external force of sexual functioning' were physical overload and exercise, which accounted for 41.1%. The predictors to explain the factor score of 'sexual activity' were family monthly income, catholics, and exercise, and which accounted for 35.4%. Above results lead us to some consensus that sexual function of women with coronary artery disease is related to various factors including vasogenic factors such as total serum cholesterol level, number of coronary vessel affected, an endocrinal factor such as menopausal state, and type A behavior pattern as a sociopshychological factor. And also health behaviors such as fitness care, overwork, weight control, and emotional tension are contributed to sexual function.

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