• 한국정밀공학회지
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• 제14권7호
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• pp.82-90
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• 1997

When a structure is made by the process of forging, it has the different mechanical properties from those it has before the process. This study is based on the crack closure phenomenon of the crack growth behavior of forged AI7050-T7452. The specimens were prepared in three kinds of forging ratio in order to find out the effects of crack closure on the forged material and compare the crack growth behavior with not-forged aluminum. COD method and strain gage method were used in measuring the crack closure stress and the results from those methods were compared each other. FEM analysis was applied to verify the effective stress intensity factor range by the superposition of the crack closure load to the crack tip. In the result of this study, the crack closure stress decreased with increasing the forging ratio due to the finer grain size and the brittle manner.

• Child Health Nursing Research
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• 제28권1호
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• pp.23-40
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• 2022

Purpose: This systematic review and meta-analysis investigated the effects of parenting education programs (PEPs) for refugee and migrant parents. Methods: A systematic review was conducted according to PRISMA guidelines. Relevant studies published from 2000 to 2020 were identified through a systematic search of six electronic databases (PubMed, Embase, Cochrane Library, CINAHL, RISS, KMBASE). A meta-analysis of the studies was then undertaken. Results: Of the 14,996 published works identified, 23 studies satisfied the inclusion criteria, and 19 studies were analyzed to estimate the effect sizes (standardized mean differences) of the PEPs using random-effect models. PEPs were effective for parenting efficacy (effect size [ES]=1.40; 95% confidence interval [CI]: 1.14-1.66), positive parenting behaviors (ES=0.51; 95% CI: 0.30-0.73), parent-child relationships (ES=0.38; 95% CI: 0.22-0.53), and parenting stress (ES=0.64; 95% CI: 0.50-0.79). There were statistically significant differences in the effect sizes of PEPs that included mothers only (ES=0.93), included children under 7 years of age(ES=0.91), did not include child participation (0.77), continued for 19 or more sessions (ES=0.80), and were analyzed in quasi-experimental studies (ES=0.86). The overall effect of publication bias was robust. Conclusion: PEPs were found to be effective at improving parenting efficacy, positive parenting behaviors, parent-child relationships, and parenting stress.

• 한국지반공학회논문집
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• 제21권8호
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• pp.27-35
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• 2005

액상화에 따른 지반의 과도한 변형으로 인한 피해가 자주 발생되고 있다. 그에 따른 지반의 움직임을 예측하기 위해서는 유효응력 개념에 기초한 수치해석 기법이 요구되어 진다. 본 연구에서는 지진 및 유사한 반복 하중에 따른 수압의 상승을 예측할 수 있는 연성(fully coupled) 유효응력 구성모델인 UBCSAND를 제안하였다. 제안된 모델은 간단한 완전탄소성모델인 Mohr-Coulomb을 변형한 형태로 마찰각(friction angle)과 팽창각(dilation angle)을 점진적으로 증가시킴으로써, 기존의 파괴상태내에서도 연속적인 소성변형 발생을 표현할 수 있다. 항복함수는 전단응력과 평균응력의 비인 $(\sigma'_1-\sigma'_3)/(\sigma'_1-\sigma'_3)$로 나타내며, 응력도의 원점에서 시작하는 무한개의 방사선을 의미한다. 따라서, Mohr-Coulomb의 파괴면과 같은 형태의 무수한 항복면을 가진다. 소성 경화법칙은 등방경화(isotropic hardening)와 이동경화(kinematic hardening)를 혼합한 형태를 이루고 있다. 재하(loading) 및 재재하(reloading)시에는 연속적인 소성 변형이 일어나나, 제하(unloading)시에는 탄성변형을 가정하였다. 제안된 모델은 느슨한 Fraser River 모래를 이용한 직접단순전단시험(Direct simple shear test)결과와 비교하여 검증하였다.

• 가정과삶의질연구
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• 제25권6호
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• pp.83-94
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• 2007

The purpose of this study was to examine the relationships between ego- resilience and stress coping styles of adolescents. The study also tried to identify differences on stress coping styles based on the level of ego- resilience of adolescents. Ego-resilience showed positive correlations with problem-focused and social support seeking coping styles and a negative correlation with an emotion-focused coping style. Canonical Correlation analysis revealed that self-confidence among four sub-domains of ego-resilience made the most outstanding contributions in predicting stress coping styles of adolescents. The problem-focused coping style had the highest correlation with ego-resilience among the four coping styles. The group of adolescents who had a higher level of ego-resilience reported more problem-focused and social support-seeking coping styles in stressful situations. The results of this study suggested that development of ego-resilience of adolescents who were in the midst of transitions and adjustment problems was important for effective coping strategies.

• 한국보건간호학회지
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• 제26권3호
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• pp.375-388
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• 2012

Purpose: The purpose this study was to examine pathways from family strengths and resilience to internet addiction through stress in male high school students Methods: Particiants in this study included 482 male students from six high schools located in Daegu and Gyeongsangbukdo, Korea. The SPSS 15.0 program and AMOS 7.0 program were used for analysis of data. Results: In this study, family strengths, resilience and stress were found to be factors influencing internet addiction. Stress was a direct factor and family strengths and resilience were indirect factors. Conclusion: Findings of this study may provide useful assistance in development of effective nursing interventions for prevention and management of male high school students' internet addiction.

• Journal of Mechanical Science and Technology
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• 제16권9호
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• pp.1033-1039
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• 2002

Partial penetration welding joint refers to the groove weld that applies to the one side welding which does not use steel backing and to both side welding without back gouging, that is, the partial penetration welding joint leaves an unwelded portion at the root of the welding area. In this study, we analyzed the residual stress and fracture on the thick metal plates that introduced the partial penetration welding method. According to the above-mentioned welding method, we could draw a conclusion that longitudinal stress and traverse stress occurred around the welding area are so minimal and do not affect any influence. We also performed the fracture behavior evaluation on the partial penetration multi pass welding with 25.4 mm thick plate by using the J-integral, which finally led us the conclusion that the partial penetration multi-pass welding method is more applicable and effective in handling the root face with less than 6.35 mm.

• 대한기계학회논문집
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• 제7권3호
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• pp.270-277
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• 1983

Plastic plane stress solutions are given for a center cracked strip, characterized by the Ramberg-Osgood plastic index, under bi-axial tension. Using a power law hardening stress-strain relation, an incremental plasticity finite element formulation is developed, and simple formulation is given for computing J-integral with nodal displacements. The near tip angular distribution of von Mises effective stress doesn't differ significantly in magnitude according to the change of loading stress and bi-axial load combination factor. But, for smaller plastic index, the location of its maximum value moves vertically at a head of crack. J-integral value, in the plastic zone near crack tip, decreases with load combination factor for large and small plastic index.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1358-1361
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• 2003

In this study, intrinsic static/dynamic fracture toughness of Al 7175-T74 are evaluated from the apparent static/dynamic toughness of notched specimen. The notch/crack critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The notch/crack critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, critical notch root radius can be predicted by notch/crack critical average stress fracture model.

• Journal of Hospice and Palliative Care
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• 제24권2호
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• pp.109-115
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• 2021

Purpose: This study aimed to investigate the effects of aroma foot baths on stress and sleep in terminally ill cancer patients. Methods: We performed a non-randomized intervention-control study with 30 terminal cancer patients who were admitted to a palliative care unit. Participants responded to questionnaires on stress and sleep before and after a 5-day interval. The intervention group received a daily aroma foot bath for 5 days. We performed multivariate regression analysis to examine the changes in outcomes on stress and sleep for the intervention group compared to the control group. Results: The differences in baseline characteristics between groups, excluding subjective economic status and general weakness, did not show statistical significance. In contrast to the control group, the intervention group showed a statistically significant change in physical stress and psychological stress levels, but significant changes were not observed in quality of sleep. Compared to the control group, the intervention group showed a significant reduction in physical stress (P=0.068) and psychological stress (P=0.021). Conclusion: Aroma foot baths are effective for reducing stress in patients hospitalized with terminal cancer.

• 한국전산구조공학회논문집
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• 제23권3호
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• pp.275-281
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• 2010

본 논문에서는 아이소-지오메트릭 형상 최적설계를 사용하여 응력 제한을 갖는 구조물의 형상 최적설계 문제를 수행하였다. 아이소-지오메트릭 해석 방법은 해석에 사용되는 기저 함수와 기하 모델을 구성하는 함수가 동일하여 기하학적으로 정확하기 때문에 설계민감도 해석 및 형상 최적설계에 있어서 많은 강점이 있다. 최적설계 문제에서 응력의 집중은 구조적인 파괴를 초래할 수 있으므로 응력 제한조건을 고려하는 것은 매우 중요하다. 아이소-지오메트릭 기법은 기하형상을 표현하는 CAD의 기저 함수를 해석에 사용함으로써 정확한 기하형상을 표현할 수 있다. 이러한 기하학적으로 엄밀한 모델을 통하여 정도 높은 응력 및 설계민감도를 얻을 수 있으며, 이를 통하여 유한요소 기반 최적설계보다 정밀한 결과를 얻을 수 있다. 수치예제에서 응력 제한조건이 있는 구조물에 아이소-지오메트릭 형상 최적설계 기법을 적용함으로써 그 효용성을 확인하였다.