• Transactions of Materials Processing
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• v.14 no.7 s.79
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• pp.635-641
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• 2005

The crystal structure of magnesium was hexagonal close-packed (HCP), so its formability was poor at room temperature. But formability was improved in high temperature with increasing of the slip planes. Purpose of this paper was to know about the mechanical properties of magnesium alloy (AZ31B), before warm and hot forming process. The mechanical properties were defined by the tension and compression tests in various temperature and strain-rate. As the temperature was increased, yield·ultimate strength, K-value, work hardening exponent (n) and anisotropy factor (R) were decreased. But strain rate sensitivity (m) was increased. As strain-rate increased, yield·ultimate strength, K-value, and work hardening exponent (n) were increased. Also, microstructures of grains fined away at high strain-rate. These results would be used in simulations and manufacturing factor fer warm and hot forming process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.69-72
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• 2005

The crystal structure of magnesium is hexagonal close-packed (HCP), so its formability is poor at room temperature. But formability is improved in high temperature with increasing of the slip planes. Purpose of this paper is to know about the mechanical properties of magnesium alloy (AZ31B), before warm and hot forming process. The mechanical properties were defined by the tension and compression tests in various temperature and strain-rate. As the temperature is increased, yield${\cdot}$ultimate strength, K-value, work hardening exponent (n) and anisotropy factor (R) are decreased. But strain rate sensitivity (m) is increased. As strain-rate increased, yield${\cdot}$ultimate strength, K-value, and work hardening exponent (n) are increased. Also, microstructures of grains fine away at high strain-rate. These results will be used in simulations and manufacturing factor for warm and hot forming process.

• Journal of Family Resource Management and Policy Review
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• v.12 no.3
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• pp.59-79
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• 2008

In this study, the investigator examined employees' work-family conflict, and analyzed its relationship with family health, to clarify the two-way influence of work-family and to verify the influence of a family friendship system based upon work-family compatibility and a healthy family. Data from 379 married female and male corporate employees were collected. Collected data were analyzed on the SPSS WIN 12.0 program. Study findings are as follows: First - For the individual, in domain variables of work-family conflict according to socio-demographic characteristics, gender has a significant influence upon strain-based conflict, family interference with work, and time-based conflict. Second - Work domain variables such as occupation, career, employment type, and working hours have a significant influence upon work interference with family, while career, and a working couple have a significant influence upon family interference with work. Finally - average housework hours and children have a significant influence upon work interference with family, whereas the length of a marriage, the average housework hours, and a housework helper have a significant influence upon family interference with work.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.101-107
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• 1999

The upset forging stage is the initial work in the forging process. It is used to remove the segregation and cavities of the ingot. Specially in handling large sized ingot, an improper upset forging can cause serious surface tearing. However, there is no detail reference for stable upset forging work. To resolve this difficulty, we studied several factors such as upset forging time, temperature varation of ingot, damage, load and stain rate etc., by using the rigid-plastic finite element approach available in the DEFORM code. Numerical simulation results indicated that: the load value of upset forging works shows severe decreasing trend at a certain point, same as strain rate. Also defects were found to be concentrated around the upper and lower portions of the ingot. With these results, we can estimate a guideline for stable upset forging work.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.66-69
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• 2002

In the ideal forming theory(1), which has been deviously developed as a direct method for optimizing forming process, material elements are required to deform following the minimum plastic work path (or the proportional true strain path). Besides the general theory(2,3), specific ideal forming theories have been developed for membrane sheet forming(4) as well as two-dimensional steady bulk forming(5-7). In this work, the ideal forming theory was successfully applied for non-steady bulk forming under the plane strain condition. Here, the shape change complying with the minimum plastic work path, was effectively described by developing a numerical code based on the characteristic method. Numerical results obtained for a specific industrial part also include the optimum pre-forming shape and its evolving shape change to the final shape as well as the boundary traction history.

• International Journal of Human Ecology
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• v.10 no.2
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• pp.1-12
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• 2009

The purpose of this study was to explore the dynamics of stepfamilies and the adjustment difficulties such families may experience. The study describes some sociodemographic characteristics of a sample of 117 stepfamilies. The independent variables were stresses due to adjustment difficulties, which were defined as "role strains". Sociodemographic variables included gender, family income level, length of time since remarriage, type of stepfamily, and the existence of any children born to the new marriage. The dependent variable was the extent of stepfamily adjustment, expressed as a scale. The factors influencing family adjustment included stepparent gender, family income level, type of stepfamily, and various role strain variables (family boundary ambiguity, role conflict, etc.). Practical recommendations for social work are made and possibilities for future research in this area are discussed based on the results of this study.

• Korean Journal of Family Social Work
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• no.54
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• pp.7-39
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• 2016

This study aimed at examining the effects of the environmental aspects of work-family role conflict on child-rearing attitudes of working mothers. To accomplish study purpose, 267 working mothers were asked to fill out the survey questionnaires. The research results were as follows. First with regards to the effects of both direction of work-family role conflict on child-rearing attitudes of working mothers: the work interference with family conflict was negatively related to affectionate child-rearing attitudes of working mothers; the work interference with family conflict was positively related to rejection child-rearing attitudes and control child-rearing attitudes of working mothers; and the family interference with work conflict was negatively related to autonomic child-rearing attitudes of working mothers. Second, in terms of the effects of the three types of work-family role conflict on child-rearing attitudes of working mothers: the work family strain-based conflict was negatively related to affectionate child-rearing attitudes of working mothers; the work family strain-based conflict was positively related to rejection child-rearing attitudes and control child-rearing attitudes of working mothers; and the family work strain-based conflict was negatively related to affectionate child-rearing attitudes and autonomic child-rearing attitudes of working mothers. Based on these results, suggestions and implications were provided.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.2
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• pp.148-158
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• 1998

The aims of this study are to evaluate the application on the stress-strain behavior of granite Soil using Lade's double work hardening constitutive model based on the theories of elasticity and plasticity. From two different sites of construction work, two disturbed and compacted weathered granite samples which are different in partical size and degree of weathering respectively were obtained. The specimen employed were sampled at Iksan and Pochon in order to predict the constitutive model. Using the computer program based on the regression analysis, 11 soil parameters for the model were determined from the simple tests such as an isotropic compression-expansion test and a series of drained conventional triaxial tests. In conclusion, it is shown that Lade's double work hardening model gives the good applicability for processing of stress-strain, work-hardening, work-softening and soil dilatancy. Therefore, this model in its present form is applicable to the compacted decomposed granite soil.

• Journal of the Korean Home Economics Association
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• v.36 no.4
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• pp.147-162
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• 1998

This study constructed a family life education program designed to help dual-earner couples reduce their role strain. This program is consisted of 6 sessions aiming for understanding the multidimensional affecting factors of role strain, strengthening family system, sharing the housework, managing time effectively reducing the additional role and adjusing standard, maintaining desirable attitude on work and family. We expect this program to be helpful in reducing dual-earner families' role strain and the active using of role strain coping strategies.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.72-79
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• 2000

Dynamic recrystallization (DRX), which may occur during hot deformation, is important for the microsturctural evolution of 304 stainless steel. Especially, the current interest in modelling hot rolling demands quantitative relationships among the thermomechanical process variables, such as strain, temperature, strain rate, and etc. Thus, this paper individually presents the relationships for flow stress and volume fraction of DRX as a function of processing variables using torsion tests. The hot torsion tests of 304 stainless steel were performed at the temperature range of 900~110$0^{\circ}C$ and the strain rate range of 5x10-2~5s-1 to study the high temperature softening behavior. For the exact prediction of flow stress, the equation was divided into two regions, the work hardening (WH) and dynamic recovery (DRV) region and the DRX region. Especially, The flow stress of DRX region could be expressed by using the volume fraction of DRX (XDRX). Since XDRX was consisted of the critical strain($\varepsilon$c) for initiation of dynamic recrystallization (DRX) and the strain for maximum softening rate ($\varepsilon$*), that were related with the evolution of microstructure. The calculated results predicted the flow stress and the microstructure of the alloy at any deformation conditions well.