• Geomechanics and Engineering
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• v.13 no.2
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• pp.285-300
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• 2017

Shallow coal resources are increasingly depleted, the mining has entered the deep stage. Due to "High stress, high gas, strong adsorption and low permeability" of coal seam, the gas drainage has become more difficult and the probability of coal and gas outburst accident increases. Based on the flow solid coupling theory of coal seam gas, the coupling model about stress and gas seepage of coal seam was set up by solid module and Darcy module in Comsol Multiphysics. The gas extraction effects were researched after applying hydraulic technology to increase permeability. The results showed that the effective influence radius increases with the expanded borehole radius and drainage time, decreases with initial gas pressure. The relationship between the effective influence radius and various factors presents in the form: $y=a+{\frac{b}{\left(1+{(\frac{x}{x_0})^p}\right)}}$. The effective influence radius with multiple boreholes is obviously larger than that of the single hole. According to the actual coal seam and gas geological conditions, appropriate layout way was selected to achieve the best effect. The field application results are consistent with the simulation results. It is found that the horizontal stress plays a very important role in coal seam drainage effect. The stress distribution change around the drilling hole will lead to the changes in porosity of coal seam, further resulting in permeability evolution and finally gas pressure distribution varies.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.27-39
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• 2007

This paper investigates numerically characteristics of the fluid flow in spatially correlated variable-aperture fractures under effective normal stress conditions. Spatially correlated aperture distributions are generated by using the geostaistical method (i.e. Turning Bands algorithm). In order to represent a nonlinear relationship between the effective normal stress and the fracture aperture, a simple mechanical formula is combined with a local flow model. Obtained numerical results indicate that the fluid flow is significantly affected by the geometry of aperture distribution varying according to the applied effective normal stress as well as the spatial correlation length of aperture distribution. Moreover, by using results simulated in this study, the modified Louis formula representing the relationship between the effective normal stress and the effective permeability of fracture is proposed.

• Journal of Korean Academy of Nursing
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• v.48 no.5
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• pp.578-587
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• 2018

Purpose: This study aimed to understand the mechanisms of decision regret and stress of family surrogates' end-of-life decision making using an exploratory path model. In particular, the research identified the direct effects of perceptions of uncertainty and effective decisions on decision regret and stress, and examined the indirect effects of being informed, having clear values, and being supported for decision regret and the stress of end-of-life decision making through the mediating variables of perceptions of uncertainty and effective decisions. Methods: Data were collected from 102 family surrogates who had participated in end-of-life decision making for patients with terminal cancer in a tertiary hospital. Results: Perception of effective decisions was a significant direct predictor of decision regret, and uncertainty was a significant predictor of stress among the participants. Being informed, having clear values, and being supported had a significant indirect influence on decision regret through the perception of effective decisions among family surrogates. However, only having clear values had a significant indirect influence on stress through the perception of uncertainty. The model explained 63.0% of decision regret and 20.0% of stress among the participants and showed a good fit with the data, ${\chi}^2=12.40$ (df=8, p=.134), TLI=.97, and RMSEA=.07. Conclusion: Nurses can support family surrogates in end-of-life decision-making processes to decrease their decision regret by providing information about end-of-life care choices, clarifying personal values, and supporting the decision-making process, and to relieve their stress by facilitating the clarification of personal values.

• Journal of Ocean Engineering and Technology
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• v.5 no.1
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• pp.71-80
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• 1991

This paper reveals the effect of the effective case depth(ECD) on the fatigue behavior of a high-frequency induction hardened SM45C in rotated bending fatigue test. In addition, the effects of fracture modes(surface origin type, inner origin type) on it are discussed. The fatigue limit of the induction hardened steel is remarkably increased compared with that of base metal. In addition, the fatigue limit is linearly increased as the effective casedepth grows deep in the region of this experiment (ECD/R;0.23-0.49). The S-N curve and fracture mode in the induction case hardened steel are classified into two kinds, as a result : N$_{f}$<10$^{5}$ ;surface origin type fracture(at high stress), N$_{f}$>10$^{5}$ ; in ner origin type fracture(at low stress). In case of inner origin type fracture; as the effective case depth(ECD) gets deep, the fatigue limit is increased by the reason that the fracture origin moves toward center; in reverse, is decreased by reason that the compressive residual stress gets low. As a result, the increasing effect of the former is much bigger than the decreasing effect of the latter, and the fatigue limit is increased as the ECD gets deep.eep.

• Journal of the Korean Home Economics Association
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• v.39 no.9
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• pp.63-78
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• 2001

The purpose of this study is to compare how different the belief, social support, stress, coping and motivation between the Korean and American children. The data was collected from 157 Korean and 114 American students (5·8th grade). The resets were as follows: 1. Korean children's other dependency and pessimism level was significantly higher than those of American children. Also Korean children perceived higher than American children in the control-pressure stress and elf-respect stress. 2. Pessimism was observed the highest effect factor on Korean children's stress. 3. Korean students tried various coping under the relationship stress. 4. Problem oriented coping was found as an effective coping in Korean children. But the pursuit of support was found as an effective coping in American children.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.660-665
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• 2003

The true stress - true strain relation of SA508 steel was evaluated with analytical and experimental equation on the base of the indentation load-depth curve obtained from the modeling of ball indentation test. The evaluated relation between true stress and true strain is agreed well with that of SA508 teel defined in the modeling. The distribution of effective stress along the center axis of indentation depth was calculated with Tresca criteria in the modeling. The representative strain, which are defined in this study as the corresponding strains obtained from the maximum effective stress, have a linear relation with the true strain. The true stress - true strain relation of austenitic stainless steel was evaluated by the modeling of ball indentation test to verify the case of A508 steel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.515-523
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• 2003

Shape memory is physical phenomenon which a platically metal is restored to its original shape by a solid state phase change by heating. TiNi alloy the most effective material in the shape memory alloy(SMA). To study(measure) recovery stress of intelligent composite. Ti50-Ni50 shape memory matrix with prestrain SMA fiber. When SMA fiber of the intelligent composite is heated over austenite starting temperature(As) by electric heating. a recovery stress are generated. The recovery stress of the intelligent composite was measured by strain gage or photoelastic experiment. Measuring method of recovery stress by photoelastic experiment was developed in this research. It was certified that photoelastic experiment was more effective and more precise than strain gage method in the measurement of recovery stress.

• Child Health Nursing Research
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• v.6 no.3
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• pp.423-436
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• 2000

This study was designed to find the characteristics and patterns in subjectivity of the perspectives on the coping strategies about practical stress in nursing student. Q-methodology was used as a research design and the research procedures were as follows. Q-sampling has been derived from the literature review and a questionnaire. Its credibility and validity were also tested by nursing professors. Total of 34 statements were selected. P-sampling has been drawn and 51 samples were selected. Based on 9 point scale, the selected respondents rated their operant definition on the perspectives on the coping strategies about practical stress in nursing student. The results of above procedures were analyzed by PCQ program. The perspectives on the coping strategies about practical stress in nursing student were analyzed based on the typical array, extreme comments, and the demographic information of study subjects. The results revealed that there were three types of the perspectives on the coping strategies about practical stress in nursing student. The three types were named as follows; 1) The first type, agree of positive change by oneself perspectives, was consisted of 18 subjects. They thought that they did their best positive change for the most effective coping strategies about practical stress. 2) The second type, agree of social support perspectives, was consisted of 13 subjects. They thought that they asked for an other person's help for the most effective coping strategies about practical stress. 3) The third type, agree of looking on avoidance perspectives, was consisted of 5 subjects. They thought that they looked on or avoided problems for the most effective coping strategies about practical stress. As a result, this study discovered three types of the degree of the perspectives on the coping strategies about practical stress in nursing student. By identifying the nature of each of three types, this study can be useful to develop efficient coping strategies about practical stress in nursing student.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.564-569
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• 2008

Strain hardening behavior during hydroforming has been experimentally investigated. The variation of flow stress was used as an index of strain hardening during respective processes and the flow stress was estimated from the correlationship between flow stress and effective strain. The local hardness after hydroformig was also predicted by effective strain. By using the inter-relationships between hardness-flow stress-effective strain at variable pre-strains, the strain hardening behavior during hydroforming has been successfully analyzed. The comparison of predicted hardness with measured hardness confirmed that the methodology used in this study was feasible and the strain hardening behavior can be quantitatively estimated.

• Culinary science and hospitality research
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• v.14 no.4
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• pp.339-356
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• 2008

The purpose of this study is to provide the developmental basic data of a change in shift work types by making a self-administered survey of the effect of commitment by shift work and the open kitchen system on job satisfaction and job stress, and mutual relation between variables on 287 cooks in luxury hotels. Analysis showed that the operation of the shift work system was effective in reducing the internal stress of the cooks, their external stress, or their self-uncertainty on the job, and the business by the open kitchen system was effective in raising self-esteem. In addition, job commitment by shift work and the open kitchen system were effective in promoting the job satisfaction of employees, interpersonal relations, promotion, benefits and wages. Consequently, the decrease of external and internal stress or self-uncertainty and the improvement of job satisfaction can be connected with the increase of productivity or cost reduction. Therefore, the open kitchen system should be properly applied to the shift work system, along with sanitation, safety and the periodic checkup of kitchen.