• Title, Summary, Keyword: Effect size

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Analysis of Size Effect of Nano Scale Machining Based on Normal Stress and Indentation Theories (수직응력과 압입이론에 기반한 나노스케일 기계가공에서의 크기효과 분석)

  • Jeon, Eun-chae;Lee, Yun-Hee;Je, Tae-Jin
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.6
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    • pp.1-6
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    • 2018
  • Recently nano meter size pattern (sub-micro scale) can be machined mechanically using a diamond tool. Many studies have found a 'size effect' which referred to a specific cutting energy increase with the decrease in the uncut chip thickness at micro scale machining. A new analysis method was suggested in order to observe 'size effect' in nano scale machining and to verify the cause of the 'size effect' in this study. The diamond tool was indented to a vertical depth of 1,000nm depth in order to simplify the stress state and the normal force was measured continuously. The tip rounding was measured quantitatively by AFM. Based on the measurements and theoretical analysis, it was verified that the main cause of the 'size effect' in nano scale machining is geometrically necessary dislocations, one of the intrinsic material characteristics. st before tool failure.

The effect of the surface defect from micro-hole for fatigue strength (피로강도에 대한 표면미소 결함의 영향)

  • 오환섭
    • Journal of the korean Society of Automotive Engineers
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    • v.11 no.1
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    • pp.51-56
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    • 1989
  • This study was performed to investigate the effect of defect on fatigue strength under the stress of rotary bending. The specimens were made of low carbon steel having artificial microholes, namely, single micro-hole and two adjacent micro-holes as natural defects, and the effects of the diameter of hole and the distance between the holes on fatigue strength have been investigated. The obtained result can be summarized as follows: 1, The critical defect means the largest size of defect that does not affect fatigue limit, and correspondes to the size of defect leading to final fracture under fatigue limit of smooth specimen. The size of defect which has an effect on fatigue limit is larger than that of critical defect. 2, The defect larger than the critical defect affects fatigue strength for as a kind of size effect, and the physical meaning of size effect of defect is considered same as the one of notch effect.

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Binocular Visual Functions Effect of Vision Therapy Programs : A Meta-Analysis (Vision Therapy 프로그램의 양안시기능 개선 효과에 대한 메타분석)

  • Lee, Jeong-Yun;Park, Chun Man
    • Journal of Korean Ophthalmic Optics Society
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    • v.20 no.2
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    • pp.201-210
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    • 2015
  • Purpose: In order to aggregate effect of the improvement of binocular vision function by vision therapy, total mean effect size, mean effect size by dependent variables, and effect size by characteristics of the subjects and characteristics of treatment were analyzed by meta-analysis. Methods: We analyzed data from 14 Korean National primary studies, which reported effects of vision therapy programs, using meta-analysis. Results: The effect size of total mean was 1.207, which showed high effect. The mean effect size according to the subcategory of the binocular dysfunctions was the highest for vergence dysfunctions group (2.989), followed by accommodative dysfunctions group (0.868) and group with both vergence dysfunctions and accommodative dysfunctions (0.692). The effect size according to the characteristics of the subjects was the highest in the vision therapy conducted in the binocular dysfunctions group (2.509) that had no other dysfunctions. The mean effect size according to the number of programs was the highest (2.310) for 7 times a week. Vision therapy for improving the binocular functions was the most effective (2.019) in 8 weeks later from vision therapy start. Conclusions: It can prove that the therapy for the improvement of binocular vision function is effective through that each result of the vision therapy effect is converted to mean effect size, and being objectifying the mean effect size.

A Meta-analysis of the Factors Related to Psychological Burn-out of Early Childhood Teachers (유아교사의 심리적소진과 관련된 요인에 대한 메타분석)

  • Moon, Dong-Kyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.38-52
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    • 2018
  • This study examined the effect sizes of psychological burnout-related factors on the psychological burnout of early childhood teachers by applying meta - analysis focusing on master 's theses, doctoral dissertations and journals that have been published in Korea for the past 20 years. The results of the analysis are as follows. First, the total effect size, the factor group, the sub-factor, and the positive and negative effect factors of the inducing and inhibiting factors showed a significant effect size. Second, in terms of inducing factors, the task problem group showed a larger effect size than the negative relationship group. Third, among the lower factor of the negative relationship group, all the sub factors excluding the negative relationship with the director, effect size showed a medium effect size. Fourth, task stress showed the greatest effect size among the sub factors of the task factor group, followed by role conflict, task overload, and role ambiguity. Fifth, resilience showed the greatest effect size among the inhibition factors, followed by organizational support factor, teacher efficacy factor, social support factor, and emotional factor. Sixth, all sub factors of the emotional labor factor group, organizational support factor of the organizational support factor group, general teacher efficacy factor of the teacher efficacy factor group, and all sub factors of social support factor Medium effect size. In addition, the lower factor of all the other factors showed a large effect size. Seventh, of the effect factors, job satisfaction factor, depression factor, and turnover intention factor all showed a large effect size.

Effects of Aquatic Intervention on Range of Motion, Gross Motor Function and Balance in the Children with Cerebral Palsy : Meta-Analysis (뇌성마비 아동의 수중 중재가 관절가동범위와 대동작기능 및 균형에 미치는 효과 : 메타분석)

  • Choi, Kibok;Cho, Sunghyoun
    • Journal of The Korean Society of Integrative Medicine
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    • v.7 no.3
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    • pp.71-83
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    • 2019
  • Purpose: This meta-analysis aimed to analyze to the effects of aquatic exercise programs in children with cerebral palsy and identify directions for future research. Methods: A systematic search based on the PRISMA guidelines was undertaken for studies conducted between 2006 and 2018 on aquatic exercise programs in children with cerebral palsy. A total of 10 studies were selected according to the inclusion criteria. The methodological quality was assessed using the Risk of Bias Tool for Randomized Controlled Trials (RoB) and Risk-of-Bias Assessment Tool for Non-randomized Studies (RoBANS). A meta-analysis software (CMA 3.0) was used to calculate the mean effect size, effect size by intervention (Halliwick and Watsu Aquatic methods), and effect size by outcome. Results: The mean effect size was 0.457. The effect size by intervention was largest for the Halliwick method, followed by the Watsu method. The effect size by outcome was largest for range of motion, followed by the gross motor function measure, the Pediatric Berg Balance Scale, and the Modified Ashworth Scale. Meta-regression analysis showed effect size increased when sample size, number of sessions, and length of sessions increased. Conclusion: The results show that aquatic exercise programs have a positive effect on children with cerebral palsy. Therefore, it is necessary to develop a guideline that recommends the appropriate intervention and the identifies the direction of future studies on aquatic exercise programs.

Size Effect of Concrete Structures with Dissimilar Initial Cracks (비유사 균열이 있는 콘크리트 구조의 크기효과)

  • 김진근;어석홍;장정수;조성찬
    • Magazine of the Korea Concrete Institute
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    • v.2 no.1
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    • pp.91-100
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    • 1990
  • In most of the structural members with initial cracks(or initial notches), the strength tends to decmase as the member size increases. This phenomenon is known as size effect. Among the structural materials of glass, metal or concrete, etc., concrete represents the size effect even without initial crack. According to the previous size effect law, the concrete mem¬ber of very large size can resist little stress. Actually, however, even the large size member can resist some stress if there is no initial crack made artificially, consequently showing a rather milder strength reduction compared to the severe strength reduction by tbe previously derived size effect law. In this study, the theoretical size effect law previously derived by Z.P. Bazant was discussed based on nonlinear fracture mechanics of concrete structures With dissimilar initial cracks, and the prediction models are proposed by regression analysis with the existing test data of more large size speciments for splitting tensile strength, shear strength and uniaxial compressive strength tests.

Development of the Size Effect Model for More Accurate Cutting Force Prediction (향상된 절삭력 예측을 위한 Size Effect 모델의 개발)

  • 윤원수;조동우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.995-1000
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    • 2000
  • In this paper. a mechanistic model is first constructed to predict three-dimensional cutting forces, and the uncut chip th thickness is calculated by following the movements of the position of the center of a cutter, which varies with the nominal feed, cutter deflection and runout. For general implementation to a real machining, this paper presents the method that determines constant cutting force coefficients, irrespective of the cutting conditions or cutter rotation angles. In addition, this study presents the approach which estimates runout-related parameters. the runout offset and its location angle, using only one measurement of cutting forces. For more accurate cutting force predictions, the size effect has to be considered in the cutting force model. In this paper, two approximate methods are suggested since the strict approach is practically impossible due to a measurement problem. The size effect is individually considered for narrow and wide cuts.

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Estimation on a Contact Size Effect in Fretting Fatigue Between Cylindrical Pad and Flat Specimen (실린더형 패드와 평판 시험편간 프레팅 피로의 접촉폭 크기효과에 관한 평가)

  • Kim, Jin-Kwang;Cho, Sang-Bong
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.6
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    • pp.116-125
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    • 2008
  • In general, fretting is a contact damage process due to micro-slip associated with small amplitude oscillatory movement between two surfaces in contact. Previous studies in fretting fatigue have observed a contact size effect related to contact width. The volume-averaging method of theoretically predicted contact stress fields was required to emulate experimental trends and to predict the observed contact size effects. This contact size effect is captured by the mean values of stresses and strains at the element integration points of FE model and two critical plane models (SWT, FS) in the present paper. It is shown that crack nucleation and fretting fatigue life can be predicted by the FE-based critical plane models.

Remaining life prediction of concrete structural components accounting for tension softening and size effects under fatigue loading

  • Murthy, A. Rama Chandra;Palani, G.S.;Iyer, Nagesh R.
    • Structural Engineering and Mechanics
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    • v.32 no.3
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    • pp.459-475
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    • 2009
  • This paper presents analytical methodologies for remaining life prediction of plain concrete structural components considering tension softening and size effects. Non-linear fracture mechanics principles (NLFM) have been used for crack growth analysis and remaining life prediction. Various tension softening models such as linear, bi-linear, tri-linear, exponential and power curve have been presented with appropriate expressions. Size effect has been accounted for by modifying the Paris law, leading to a size adjusted Paris law, which gives crack length increment per cycle as a power function of the amplitude of a size adjusted stress intensity factor (SIF). Details of tension softening effects and size effect in the computation of SIF and remaining life prediction have been presented. Numerical studies have been conducted on three point bending concrete beams under constant amplitude loading. The predicted remaining life values with the combination of tension softening & size effects are in close agreement with the corresponding experimental values available in the literature for all the tension softening models.

Meta-analysis about the Effectiveness of Intervention Programs for Married Immigrant Women (결혼이주여성에게 적용한 중재 프로그램의 효과성에 대한 메타분석)

  • Lee, Mi Ok;Kim, Sinhyang
    • Korean Journal of Women Health Nursing
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    • v.21 no.4
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    • pp.342-354
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    • 2015
  • Purpose: The purpose of this study was to test the effect size of intervention programs for married immigrant women as well as to suggest the basic data for health care practices for married migrant women. Methods: Meta-analysis was conducted with 27 articles from domestic Korea master's and doctorate degree dissertations and Korea academic journals from 2007 to 2014. Results: Overall average effect size was 1.17 and 'parental education' of Intervention Variables was the biggest effect size. Intervention Variables were also identified to be the most desirable in cases when total sessions were applied with 10-18 sessions, 1 session per week, 90-120 minutes per session activity time and with less than 10 subjects in group size. Regarding effect variables, psychological variable group was identified to show the biggest effect size and in sub-variables, self-efficacy was identified to show the biggest effect size. Conclusion: If intervention programs for married immigrant women is expanded and conducted based on the results of this study, the program would have significant affect psychological, social and physical health of the married migrant women who currently occupy the important status in our society.