• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.29-34
• /
• 2002

The heat of hydration of cement causes the internal temperature rise at early age, paticular in massive concrete structures. As the results of the temperature rise and restraint condition, the thermal stress may induce cracks in concrete. The prediction of the thermal stress is important in design and construction stages in order to control the cracks in mass concrete. It is poor economy to analysis for prediction of the thermal stress on each design or construction. In this study, the hydration heat and thermal stress analysis is performed by ABAQUS program, as a results of thermal analysis, the formula of size-placing depth relationship is proposed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.2 no.1
• /
• pp.51-56
• /
• 2003

A custom application system, which was based on the finite element analysis, for stress on the head-skirt junction of a hot pressure vessel was developed. This is useful computer-based analysis system which designed to provide an analysis technique and knowledge conveniently available to other people. It was found the evaluation of thermal stress of several typed skirt joint of a pressure vessel could be performed early using this system.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.281-286
• /
• 1999

Nonlinear temperature distribution induced by the hydration heat generates thermal stress in mass concrete. At early ages, such thermal stress may induce thermal cracks in the structure which can affect on the durability and safety of the structure. Up to now, a lot of works have focused on the prediction of temperature distribution and thermal stress in the structure. In most of such works, however, the inside of structure was considered as adiabatic state to predict temperature distribution and the thermal stress. And due to the lacks of appropriate analysis models after crack, there was little research on the crack occurrence. This paper deals with the prediction of the temperature distribution in the structure using the rate of hydration heat generation and also estimates the behavior of structure before and after cracking due to hydration heat using crack band model.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.193-198
• /
• 1998

In this study, the change of concrete temperature, strain and thermal stress were measured by using the embedded type concrete gauges in tendon gallery wall of containment building. A finite element analysis was performed to clarify the thermal behavior of concrete. The analytic and test results were investigated to improve the validity of analytic method. According to the test results, concrete temperature, strain and thermal stress were strongly affected by measuring point and environment condition of member. And the thermal stress was developed in the member which was not demoulded at early ages. This is caused by the change of internal temperature and restrained condition. A finite element effectively interpreted the test results by estimating the concrete properties and the site condition.

• Journal of KSNVE
• /
• v.10 no.4
• /
• pp.686-691
• /
• 2000

In this paper a computer aided analysis method is proposed for durability assessment in the early design stages using dynamic analysis, stress analysis and fatigue life prediction method. From dynamic analysis of a vehicle suspension system, dynamic load time histories of a suspension component are calculated. From the dynamic load time histories and the stress of the suspension component, a dynamic stress time history at the critical location is produced using the superposition principle. Using linear damage law and cycle counting method, fatigue life cycle is calculated. The predicted fatigue life cycle is verified by experimental durability tests.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.445-450
• /
• 2006

It is proposed that the electromechanical relation of the conductive materials with high electrical resistance may be used to estimate the current stress of prestressing tendons. To choose the best conductive material to this end, we studied the electromechanical relations of carbon fibers and metalic heat wires experimentally. It is found that the relation of carbon fibers can be modelled by a parabolic(or hyperbolic) function in the early stage of deformation. However because the relation is not consistent when it is unloaded and reload, carbon fibers are not suitable for this purpose. Metallic heat wires show a consistent linear relation during loading and unloading in the elastic deformation and are suitable for this purpose. To estimate the electromechanics relation of metallic wires, we developed a simple formula based on the rigid plasticity. We propose a new kind of prestressing tendons whose stress can be monitored.

• Journal of Families and Better Life
• /
• v.29 no.2
• /
• pp.39-50
• /
• 2011

The purpose of this study is to analyze the research trends in articles on parenting stress published in Korean academic journals. Between 1996 and 2010, 116 articles on parenting stress were published in 16 reliable journals in Korea. This study analyzed research frequency, contents and methodology. Results show that the number of studies has increased during the years. Most studies used methods categorized as quantitative data and cross-sectional surveys. The most frequently used measurement scale was Abidin's Parenting Stress Index. Many were analyze by using regression. The main content of these studies were the factor related to parenting stresses and the relationship between the factors and parenting stress.

• The Korean Journal of Community Living Science
• /
• v.14 no.1
• /
• pp.1-12
• /
• 2003

The purpose of this study was to investigate the maternal parenting stress and related variables through early childhood in rural areas (Iksan and Kimpo). The subject were 134 mothers who have less than 5-year old children. The statistics used for this data were freguency, percentile, t-test, ANOVA, and multiple regression analysis. The main results obtained from this study were as follows. The degree of maternal parenting stress differed according to level of mother's education, sex of the child, physical and mental health of the mother, child rearing attitudes, mother's level of self-differentiation, marital satisfaction, and father's parenting support. Results of the regression analysis that the etiologic model of this study were that father's parenting support is the most effective variables in rural areas.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.260-263
• /
• 2005

In this study, we analyzed the plantar shear stress and pressure of diabetic foot patients during walking by using in-shoe local shear force and plantar pressure measurement system. Twelve normal subjects and three diabetic foot patients with diabetic neuropathy in lateral heel were participated in this study. The center of pressure in diabetic foot patients moved more medially and directed toward 1st, 2nd metatarsal heads and hallux during late stance period, making pressure at the medial heel and 2nd metatarsal head significantly higher than in the normal. Shear stress at the heel were changed significantly in early stance and the magnitude of shear stresses in each metatarsal head were also changed. Further studies would be very helpful to design foot orthoses in patients with diabetic neuropathy or other diseases.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.1
• /
• pp.1-10
• /
• 2018

It is difficult to predict the early-age cracks of strain restrained concrete members due to environmentally sensitive parameters. A new method is proposed to predict the cracks by test of autogenous deformation and self-induced restrained stress of specimens which simulates early-age crack state by hydration heat of the'Wall-On-Foundation'members. For this purpose, thermal analysis of entire structure considering the environmental condition is performed at first, and the specimens are set up where hydration heat was electronically controlled according to the analysis results. By measuring free deformation and force to compensate the autogenous strain including relaxation, feasibility of cracks can be estimated. The proposed method can predict the occurrence of cracks better than the material test of the early age concrete which has large variance. The method of this study is particularly useful when it is used as a preliminary experiments to predict the crack more precisely before full-scale concrete placement in construction of large structures.