• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.285-291
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• 2016

The purpose of this study was to evaluate the structural capacity of steel pipe pile specimens reinforced with hollow steel plate shear connectors by pull-out test. Compressive strength testing of concrete was conducted and yield forces, tensile strengths and elongation ratios of re-bars and hollow steel plate were investigated. A 2,000kN capacity UTM was used for the pull-out test with 0.01mm/sec velocity by displacement control method. Strain gauges were installed at the center of re-bars and hollow steel plates and LVDTs were also installed to measure the relative displacement between the loading plate and in-filled concrete pile specimens. The yield forces of the steel pipe pile specimens reinforced with hollow steel plate shear connectors were increased 1.44-fold and 1.53-fold compared to that of a control specimen, respectively. Limited state forces of steel pipe pile specimens reinforced with hollow steel plate shear connectors were increased 1.23-fold and 1.29-fold compared to that of a control specimen, respectively. Yield state displacement and limited state displacement of steel pipe pile specimens reinforced with hollow steel plate shear connector were decreased 0.61-fold and 0.42-fold compared to that of a control specimen, respectively.

• Journal of dental hygiene science
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• v.14 no.4
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• pp.433-441
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• 2014

This study was aimed to analyze factors affecting intention on clinical application by task autonomy of dental hygienists, expected effect and obstructive factor on clinical application of assessment, dental hygiene diagnosis, planning, implementation, and evaluation (ADPIE). Meanwhile, it proved mediating effects of "attitude toward ADPIE" when it came to "intention on clinical application". The data was collected from 237 dental personnel in capital region from March 28, 2014 to May 2, 2014. To analyze the suitability of a theoretical model and hypothesis testing, SPSS 21.0 and AMOS 18.0 program were used. The theoretical model was accepted as it resulted in ${\chi}^2=421.67$ while showing goodness of fit index=0.858, comparative fit index=0.915, Tucker-Lewis index=0.896, root mean square residual=0.039, and root mean square error of approximation=0.099. The result showed "task autonomy of dental hygienists (${\beta}=0.398$, p<0.05)" and "expected effect on ADPIE (${\beta}=0.363$, p<0.01)" had a positive effect on "attitude toward ADPIE". Also, "attitude toward ADPIE" had a positive effect on "intention on clinical application". In addition, "task autonomy of dental hygienists" and "expected effect on ADPIE" had an indirect influence on "intention on clinical application" via such intermediary as "attitude toward ADPIE". According to the above results, the task autonomy of dental hygienists, expected effect on ADPIE, and attitude toward ADPIE were confirmed to be significant factors when it came to the intention on its clinical application. Therefore in order to settle ADPIE in the clinical practice, improvement of task autonomy for dental hygienists as well as their expectation and attitude on ADPIE must be promoted.

• Culinary science and hospitality research
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• v.22 no.7
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• pp.187-202
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• 2016

The purpose of this study was to better understand the influence of psychological contract breach in deluxe hotel culinary staff memeberss on job satisfaction and turnover intention. Based on a total of 280 samples obtained for empirical research, this study reviewed the reliability and fitness of the research model and verified a total of 4 hypotheses using the AMOS program. The hypothesized relationships in the model were simultaneously tested by using a structural equation model(SEM). The proposed model provided an adequate fit to the data, ${\chi}^2=334.152$ (p<.001), df=162, CMIN/DF=2.063, GFI=.893, AGFI=.861, NFI=.919, CFI=.956, RMSEA=.062. The model's fit, as indicated by these indexes, was deemed satisfactory, thus providing a good basis for testing the hypothesized paths. The SEM showed that relational contract breach (${\beta}=-.236$) had a negative significant influence on job satisfaction. In addition, job satisfaction (${\beta}=-.236$) had a negative significant influence on turnover intention. The moderating effects on career the formulated model was verified. Limitations and future research directions are also discussed.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.595-602
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• 2006

An experimental study was conducted to investigate seismic behaviour of post-tensioned(PT) exterior slab-column connections used for the purpose to resist gravity loads only. For these, 2/3-scale, two PT post-tensioned exterior connections with two different tendon arrangement patterns and one conventional reinforced concrete(RC) exterior connection was tested under quasi-static, uni-directional reversed cyclic loading. During the lateral testing, gravity forces transferred to the column were kept constant to closely simulate a moment to shear ratio of a real building. One of the objectives of this study was to assess the necessity and/or the quantity of bottom bonded reinforcement needed to resist moment reversal which would occur under significant inelastic deformations of the adjacent lateral force resisting systems. The ACI 318 and 352 provisions for structural integrity were applied to provide the bottom reinforcement passing through the column for the specimens. Prior test results were also collected to conduct comparative studies for some design parameters such as the tendon arrangement pattern, the effect of post-tensioning forces and the use of bottom bonded reinforcement. Consequently, the impact of tendon arrangement on the seismic performance of the PT connection, that is lateral drift capacity and ductility, dissipated energy and failure mechanism, was considerable. Moreover, test results showed that the amount of bottom reinforcement specified by ACI 352. 1R-89 was sufficient for resisting positive moments arising from moment reversal under reversed cyclic loads. Shear strength of the tested specimens was more accurately predicted by the shear strength equation(ACI 318) considering the average compressive stress over the concrete($f_{pc}$) due to post-tensioning forces than that without considering $f_{pc}$.

• The Journal of Advanced Prosthodontics
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• v.1 no.3
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• pp.113-117
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• 2009

STATEMENT OF PROBLEM. Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported. PURPOSE. The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM). MATERIAL AND METHODS. Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad $S\ddot{a}ckingen$, Germany) were prepared in 40 mm (length) $\times$ 4 mm (width) $\times$ 3 mm (height) samples. Specimens were artificially aged in distilled water by heat-treatment at a temperature of 75, 100, 125, 150, 175, 200, and $225^{\circ}C$ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences ($\alpha$= .05). RESULTS. The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below $125^{\circ}C$ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above $150^{\circ}C$, the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related to temperature, the minimum flexural strength was above 700 MPa. CONCLUSION. The monoclinic phase started to appear after aging treatment above $100^{\circ}C$. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic phase reached a plateau value, circa 75% above $175^{\circ}C$. The point of monoclinic concentration at which the flexural strength begins to decrease was between 12% and 54%.

• Culinary science and hospitality research
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• v.18 no.3
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• pp.72-89
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• 2012

This study aims to understand the influence of consumption value perceived by resort customers upon customer satisfaction and behavioral intention. Based on total 324 customers obtained from the empirical research, this study reviewed reliability and fitness of the research model and verified total 4 hypotheses with AMOS program. The hypothesized relationships in the model were tested simultaneously by using a structural equation model(SEM). The proposed model provided an adequate fit to the data, ${\chi}^2$=467.489(p<.001), df=326, CMIN/DF=1.434, GFI=.911, AGFI=.889, NFI=.881, CFI=.960, RMSEA=.037. The model's fit, as indicated by these indexes, was deemed satisfactory, thus it provided a good basic for testing the hypothesized paths. The result showed that the functional value(${\beta}$ .233, p<.01), social value(${\beta}$ .125, p<.05), emotion value(${\beta}$ .310, p<.001), epistemic value(${\beta}$ .144, p<.05) had a positive significant influence on customer satisfaction. Also, customer satisfaction(${\beta}$ .225, p<.01) had a positive significant influence on behavioral intention. The moderating effects by gender and marital status were found not to exist. Limitations and future research directions are also discussed.

• Culinary science and hospitality research
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• v.21 no.2
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• pp.11-26
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• 2015

The purpose of this study was to understand the influence of non-verbal communication of coffee shop employees on brand image and customer satisfaction. Based on a total of 317 samples obtained for empirical research, this study reviewed the reliability and fitness of the research model and verified a total of 3 hypotheses using the AMOS program. The hypothesized relationships in the model were simultaneously tested through the use of a structural equation model(SEM). The proposed model provided an adequate data fit, ${\chi}^2=434.380$ (p<0.001), df=178, CMIN/DF=2.440, GFI=0.886, AGFI=0.852, NFI=0.900, CFI=0.938, RMSEA=0.068. The model's fit, as indicated by these indexes, was deemed satisfactory, thus providing a good basis for testing the hypothesized paths. The SEM showed that kinesics(${\beta}=.311$), paralanguage(${\beta}=.242$), physical appearance(${\beta}=.382$) and proxemics(${\beta}=.481$) had a significant positive influence on brand image. In addition, brand image(${\beta}=.217$) had a significant positive influence on customer satisfaction. Furthermore, the effect of coffee shop employee non-verbal communication on customer satisfaction was found to be partially mediated by the brand image.

• Child Health Nursing Research
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• v.19 no.3
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• pp.228-237
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• 2013

Purpose: This study was done to test a hypothesized model, the Biobehavioral Family Model (BBFM), on the relationship of family emotional climate, security of parent-child relationship, depression symptoms and eating problems in adolescent girls, to further understanding of eating problems in this population. Methods: With a convenience sample of 647 girls, aged 15 to 18, a self-report survey was conducted which included the Korean form of the Eating Attitude Test (EAT-26) to assess eating problems. Results: The estimated results of the structural equation modeling indicated a good fit of data to the hypothesized model proposing that family emotional climate and security of parent-child relationship were associated with the risk of eating problems by way of depression symptoms. That is, negative family emotional climate and insecure parent-child relationship increased the risk of eating problems indirectly by way of depression symptoms. Conclusion: The findings are consistent with the BBFM, which suggests a psychobiologic influence of specific family processes on children's stress-sensitive physical disease activity by way of depression symptoms. Therefore, the applicability of the BBFM for understanding adolescent girls' eating problems is supported. The psychobiologic pathways from depression to eating pathology should be addressed in future studies.

• Composites Research
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• v.12 no.6
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• pp.74-82
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• 1999

The static and fatigue characteristics of polyurethane foam cored sandwich structures are investigated. Three types of the specimens with the glass fabric faces and the polyurethane foam core are used; non-stitched. stitched, and stiffened sandwich specimen. Especially additional structural reinforcements with the twisted polyester and glass fiber for thickness direction are made to stitched sandwich structure panel to minimize the delamination of structure which is stitched the upper and lower faces through the core and the resin is impregnated Into stitched fiber with the characteristics of low viscosity of resin at resin flow temperature and cured together with during the curing process. Bending strength of stitched specimen which is 50 mm $50{\times}50{\;}mm$ pitched is improved by 50 % as com-pared with non-stitched specimen and stiffened specimen is improved 10 times more than non-stitched structure. After fatigue testing of $10^6$cycles by 20% of ultimate load under monotonic load, the bending fatigue strength of non-stitched specimen is decreased by 27% of monotonic bending strength, 39% for stitched structure and 20% for stiffened specimen. To verify the aging effect of polyurethane form core, Ultrasonic C-scanning equipment is used to detect the damage of skin laminate alone after fatigue test. From results of UT C-scan images, there is no defect that can be damaged occurred during fatigue test. It is concluded that the decrease of bending strength for foam cored sandwich specimen is caused by the decrease of stiffness due to the aging of polyurethane foam core during fatigue cycles.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.69-89
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• 2009

Reinforced and prestressed concrete (RC and PC) thin walls are crucial to the safety and serviceability of structures subjected to shear. The shear strengths of elements in walls depend strongly on the softening of concrete struts in the principal compression direction due to the principal tension in the perpendicular direction. The past three decades have seen a rapid development of knowledge in shear of reinforced concrete structures. Various rational models have been proposed that are based on the smeared-crack concept and can satisfy Navier's three principles of mechanics of materials (i.e., stress equilibrium, strain compatibility and constitutive laws). The Cyclic Softened Membrane Model (CSMM) is one such rational model developed at the University of Houston, which is being efficiently used to predict the behavior of RC/PC structures critical in shear. CSMM for RC has already been implemented into finite element framework of OpenSees (Fenves 2005) to come up with a finite element program called Simulation of Reinforced Concrete Structures (SRCS) (Zhong 2005, Mo et al. 2008). CSMM for PC is being currently implemented into SRCS to make the program applicable to reinforced as well as prestressed concrete. The generalized program is called Simulation of Concrete Structures (SCS). In this paper, the CSMM for RC/PC in material scale is first introduced. Basically, the constitutive relationships of the materials, including uniaxial constitutive relationship of concrete, uniaxial constitutive relationships of reinforcements embedded in concrete and constitutive relationship of concrete in shear, are determined by testing RC/PC full-scale panels in a Universal Panel Tester available at the University of Houston. The formulation in element scale is then derived, including equilibrium and compatibility equations, relationship between biaxial strains and uniaxial strains, material stiffness matrix and RC plane stress element. Finally the formulated results with RC/PC plane stress elements are implemented in structure scale into a finite element program based on the framework of OpenSees to predict the structural behavior of RC/PC thin-walled structures subjected to earthquake-type loading. The accuracy of the multiscale modeling technique is validated by comparing the simulated responses of RC shear walls subjected to reversed cyclic loading and shake table excitations with test data. The response of a post tensioned precast column under reversed cyclic loads has also been simulated to check the accuracy of SCS which is currently under development. This multiscale modeling technique greatly improves the simulation capability of RC thin-walled structures available to researchers and engineers.