• 한국전산유체공학회:학술대회논문집
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• 1999.05a
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• pp.192-198
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• 1999

The present study proposes modified temperature-dependent non-Newtonian viscosity model and investigates flow characters and heat transfer enhancement of the viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The proposed modified temperature dependent viscosity model has non-zero value near the high temperature and high shear rate region while on the existing viscosity models have zero value. Two versions of thermal boundary conditions involving difference combination of heated walls and adiabatic walls are analyzed in this study. The combined effect of temperature dependent viscosity, buoyancy, and secondary flow caused by second normal stress difference are ail considered. The Reiner-Rivlin model is adopted as a viscoelastic fluid model to simulate the secondary flow caused by second normal stress difference. Calculated Nusselt numbers by the modified temperature-dependent viscosity model gives under prediction than the existing temperature-dependent viscosity model in the regions of thermally developed with same secondary normal stress difference coefficients with experimental results in the regions of thermally developed. The heat transfer enhancement of the viscoelastic fluid in a 2:1 rectangular duct is highly dependent on the secondary flow caused by the magnitude of second normal stress difference.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.348-360
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• 2019

This study examined the influence of humanistic knowledge and occupational stress on the professional quality of life of clinical nurses. The data from 217 survey questionnaires collected from three general hospitals located in a metropolitan area from Jun 3 to 14, 2019 were used. The data were analyzed using a t-test, ANOVA, Scheffè test, Pearson's Correlation Coefficient, and Stepwise multiple regression with SPSS Statistics 23.0 program. The findings revealed a positive correlation between compassion satisfaction and humanistic knowledge and a negative correlation with Burnout. Burnout had a negative correlation with humanistic knowledge and a positive correlation with occupational stress and secondary traumatic stress. Secondary traumatic stress showed a positive correlation with occupational stress. Burnout, satisfaction for nursing, and working period were significant variables of the compassion satisfaction with an explanatory power of 48.5%. Compassion satisfaction, secondary traumatic stress, satisfaction for nursing, marriage, and occupational stress were significant variables of burnout with an explanatory power of 68.8%. Burnout and income were significant variables of secondary traumatic stress with an explanatory power of 21.9%. Burnout was found to be a significant variable of not only compassion satisfaction, but also compassion satisfaction. Therefore, efforts are needed to make efforts to prevent burnout.

• Korea-Australia Rheology Journal
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• v.19 no.2
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• pp.67-73
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• 2007

A finite volume method (FVM) base on the SIMPLE algorithm as the pressure correction strategy and the traditional staggered mesh is used to investigate steady, fully developed flow of Oldroyd-3-constant fluids through a duct with square cross-section. Both effects of the two viscoelastic material parameters, We and ${\mu}$, on pattern and strength of the secondary flow are investigated. An amusing sixteen vortices pattern of the secondary flow, which has never been reported, is shown in the present work. The reason for the changes of the pattern and strength of the secondary flow is discussed carefully. We found that it is variation of second normal stress difference that causes the changes of the pattern and strength of the secondary flow.

• Geotechnical Engineering
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• v.10 no.4
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• pp.167-180
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• 1994

A series of long term consolidation tests were conducted under loading -unloading and loading(pc) -unloading(p.) -reloading(p,) conditions using reconstituted clay in order to investigate the effect of stress history on secondary consolidation characteristics and the applicability of the secondary consolidation model suggested by Bjerrum to overconsolidated clays. According to the test results, the secondary compression settlement affected by the stress history in the first half of experimental period and the coefficient of secondary compression, C‥‥ is dependent on overconsolidation ratio, OCR(p,1 p.), maBium OCR (p./p.), and unloading duration time. Moreover the coefficient of secondary consolidation in the latter half of experimental period Cn is mainly affected by OCR and it gradually reduces with OCR increment. Finally the comparison of the experimental results with the Bjerrum model indicates that the Bjerrum model can be applied beyond certain range of stress history in the overconsolidated clay.

• Journal of the Korean Society of School Health
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• v.23 no.2
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• pp.286-295
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• 2010

Purpose: This study was conducted to identify the factors affecting the job stress of school nurses and reducing their the job stress by analyzing degree of the stress according to the factors related to job stress. Methods: The participants were 136 school nurses who worked in Pusan province. The Data were collected by self-reporting questionnaires from Dec. 11th in 2006 to Feb. 9th in 2007. The data were analyzed by Frequency, Mean, t-test, ANOVA, Pearson Correlation Coefficient and Stepwise multiple regression analysis (SPSSwin 12.0s). Results: There was significant difference of the degree of job stress in age. There was significantly negative relationship between the job characteristics and job stress (r=-.473), job satisfaction and job stress (r=-.561), personal values and job stress (r=-.429), achievement motivation and job stress (r=-.215) at p<.01 level. The major factor which influence the degree of job stress was job satisfaction. Conclusion: The factors affecting the job stress of school nurses was correlated with one another and influenced to the degree of the job stress directly and indirectly. The factor that affected the degree of the job stress directly was the job satisfaction and the personal values. As shown this result, it is important that the factor of the job stress lies in the mental characteristics.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.262-273
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• 1991

In the present study, the steady, incompressible, isothermal, developing flow in a 90.deg. rectangular cross sectional strongly curved duct with aspect ratio 1:1.5 and Reynolds number of 9.4*10$^{4}$ has been investigated. Measurements of components of mean velocities, pressures, and corresponding components of the Reynolds stress tensor are obtained with a hot-wire anemometer and pitot tube. In general, flow in a curved duct is characterized by the secondary vortices which are driven mainly by centrifugal force-radial pressure gradient imbalance, and the stress field stabilizing effects near the convex wall and destablizing effects close to the concave wall. It was found that the secondary mean velocities attain values up to 39% of the bulk velocity and are largely responsible for the convections of Reynolds stress in the cross stream plane. Therefor upstream of the bend the Reynolds stress are low. Corresponding to the small boundary layer thickness. At successive planes, large values of Reynolds stress were observed near the concave surface and the side wall.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1120-1128
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• 1999

An elastic-viscoplastic finite element analysis is performed to investigate detailed growth behavior of creep cracks and the numerical results are compared with experimental results. In Cr-Mo steel stress fields obtained from the crack growth method by mesh translation were compared with both cases that the secondary creep rate is only used as creep material property and the primary creep rate is included. Analytical stress fields, Riedel-Rice(RR) field, Hart-Hui-Riedel(HR) field and Prime(named in here) field, and the results obtained by numerical method were evaluated in details. Time vs. stress at crack tip was showed and crack tip stress fields were plotted. These results were compared with analytical stress fields. There is no difference of stress distribution at remote region between the case of 1st creep rate+2nd creep rate and the case of 2nd creep rate only. In case of slow velocity of crack growth, the effect of 1st creep rate is larger than the one of fast crack growth rate. Stress fields at crack tip region we, in order, Prime field, HR field and RR field from crack tip.

• Korean Journal of Social Welfare
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• v.63 no.4
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• pp.33-57
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• 2011

This study aims to evaluate psychometric properties of the korean version of the secondary traumatic stress scale. A total of 238 practitioners in child protection agencies are recruited using complete enumeration method. The psychometric properties of the instrument are tested by item-analysis, exploratory factor analysis,(EFA) and convergent and construct validity. The results show that the internal consistency values for the two dimensions of the K-STSS are good. While the convergent and discriminant validity is empirically confirmed, the construct validity is not supported. The EFA with the common factor analysis method reveals the factor structure in the observed variables. The findings of the study confirmed that although it was reliable and discriminant, the K-STSS needed to be explored more in a way to support construct validity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1073-1084
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• 1999

The effects of secondary flow on the structure of a turbulent wake generated by a flat plate was investigated experimentally. The secondary flow was induced In a $90^{\circ}$ curved duct in which the flat plate wake generator was installed. The wake generator was installed in such a way that the wake velocity gradient exists in the span wise direction of the curved duct. Measurements were made in the plane containing the mean radius of curvature where pressure gradient and curvature effects were small compared with the secondary flow effect. All six components of the Reynolds stresses were measured in the curved duct. Turbulence intensities in the curved wake are higher than those in the straight wake due to an increase of the turbulent kinetic energy production by the secondary flow. In the inner wake region, shear stress and strain in the plane containing the velocity gradient of the wake show opposite signs with respect to each other, so that eddy viscosity Is negative in this region. This indicates that gradient-diffusion type turbulence models are not appropriate to simulate this type of flow.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.631-640
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• 2013

This paper provides a comparison of the J-integral estimation method under combined primary and secondary stress in the R6, RCC-MR A16 code. The comparisons of each code are based on finite element analysis using ABAQUS with regard to the crack shape, crack depth, and magnitude of secondary load. The estimate of the R6 code is conservative near $L_r=1$, and that of the RCC-MR A16 code is conservative near $L_r=0$. As a result, this paper proposes a modified method of J-integral estimation in the R6, RCC_MR A16 code. The J-integral using the modified method corresponds to the finite element analysis result.