• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1340-1346
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• 1999

The turbulent shear flow around a surface-mounted vertical fence was investigated using the two-frame PTV system. The Reynolds number based on the fence height(H) was 2950. From this study, it is revealed that at least 400 instantaneous velocity field data are required for ensemble average to get reliable turbulence statistics, but only 100 field data are sufficient for the time-averaged mean velocity information. Various turbulence statistics such as turbulent intensities, turbulence kinetic energy and Reynolds shear stress were calculated from 700 instantaneous velocity vector fields. The fence flow has an unsteady recirculation region behind the fence, followed by a slow relaxation to the flat-plate boundary layer flow. The time-averaged reattachment length estimated from the streamline distribution is about 11.2H. There exists a region of negative Reynolds shear stress near the fence top due to the highly convex (stabilizing) streamline-curvature of the upstream flow. The large eddy structure in the separated shear layer seems to have significant influence on the development of the separated shear layer and the reattachment process.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.77-82
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• 2006

Evaluation of the elliptic blending turbulence model (EBM) together with the two-layer model, shear stress transport (SST) model and elliptic relaxation model (V2-F) is performed for a better prediction of natural convection and thermal stratification. For a natural convection problem the models are applied to the prediction of a natural convection in a rectangular cavity and the computed results are compared with the experimental data. It is shown that the elliptic blending model predicts as good as or better than the existing second moment differential stress and flux model for the mean velocity and turbulent quantities. For thermal stratification problem the models are applied to the thermal stratification in the upper plenum of liquid metal reactor. In this analysis there exist much differences between the turbulence models in predicting the temporal variation of temperature. The V2-F model and EBM better predict the steep gradient of temperature at the interface of thermal stratification, and the V2-F model and EBM predict properly the oscillation of temperature. The two-layer model and SST model fail to predict the temporal oscillation of temperature.

• Steel and Composite Structures
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• v.28 no.1
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• pp.1-11
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• 2018

In this paper, local ratcheting behavior of 1045 steel plates with circular cutout was investigated. Experimental tests were carried out by a Zwick/Roell HB 100 servo hydraulic machine. In order to measure the local strain at notch root, a data acquisition system with strain gauge was used. Various notch diameters and distances of strain gauges mounted from the notch root were found influential in the magnitude of local ratcheting strain. It was found that the local maximum principal stress plays a crucial role in increasing the local plastic deformation. Numerical simulation was done by ABAQUS software using nonlinear isotropic/kinematic hardening model. Material parameters of hardening model were attained from several stabilized cycles of flat specimens subjected to symmetric strain cycles. The nonlinear kinematic hardening model along with the Neuber's rule was employed to assess local ratcheting at the notch root of steel plates. The results of the numerical simulations agreed closely with those measured values in this study. Both ratcheting progress and mean stress relaxation occurred simultaneously at the notch root.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1265-1276
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• 2005

The elliptic conceptual second moment models for turbulent heat fluxes, which are proposed on the basis of elliptic-blending and elliptic-relaxation equations, are applied to calculate the combined forced and natural turbulent convection in a vertical plane channel. The models satisfy the near-wall balance between viscous diffusion, viscous dissipation and temperature-pressure gradient correlation, and also have the characteristics of approaching its respective conventional high Reynolds number model far away from the wall. Also the models are closely linked to the elliptic blending model which is used for the prediction of Reynolds stress. In order to calibrate the heat flux models, firstly, the distributions of mean temperature and scala flux in fully developed channel flow with constant wall difference temperature are solved by the present models. The buoyancy effect on the turbulent characteristics including the mean velocity and temperature, the Reynolds stress tensor, and the turbulent heat flux vector are examined. In the opposing flow, the turbulent transport is greatly enhanced with both the Reynolds stresses and the turbulent heat fluxes being remarkably increased; whereas, in the aiding flow, the opposite change is observed. The results of prediction are directly compared to the DNS to assess the performance of the model predictions and show that the behaviors of the turbulent heat transfer in the whole flow region are well captured by the present models.

• Women's Health Nursing
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• v.7 no.2
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• pp.188-202
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• 2001

This study was designed to investigate the effect of one-to-one labor support on labor pain, labor stress response, childbirth experience and neonatal status for primipara by a quasi experiment (nonequivalent control group pretest-posttest design), from April 30, 1999 to February 20, 2000. The subjects of this experiment consisted of eighty two primipara with single gestation, full term, uncomplicated pregnancies. Forty one were in the experimental group and forty one in the control group. Their mean age was 25.95 years, their mean gestation period was 39.9 weeks. A caring package of one-to-one labor support had three components. Physical support consisted of massage, back pressure, touch. Emotional support was provided by a continuous nurse's presence, acceptance and encouragement. Informational support involved teaching breathing skills, relaxation skills and knowledge about the labor process. Data assessed labor pain, pulse rate and blood pressure to measure labor stress response. Also, in measuring the value of labor stress response, plasma epinephrine, plasma norepinephrine and serum cortisol were measured. In the 24 hours after birth, the data for the postpartum mother's childbirth experiences was collected. Umbilical cord arterial blood pH, one minute and five minute Apgar score were measured after birth. Data was analyzed by t-test, $x^2$-test, repeated measures ANOVA, ANCOVA with SAS Program. The results were as follows; 1. Labor pain was significantly low in the experimental group(P=.016). 2. No significant group effects were found, but significant time effects were found for plasma epinephrine, norepinephrine, serum cortisol, pulse rate and blood pressure. 3. The childbirth experience of the experimental group was significantly more positive than the control group (P = .005). 4. The umbilical cord arterial blood pH of the experimental group was significantly higher than the control group(P=.014). There was no significant difference between the two groups in neonatal one minute and five minute Apgar scores. In conclusion, these findings indicate that one-to-one labor support could be effective in decreasing labor pain, and increasing positive childbirth experiences, also increasing the neonatal umbilical cord arterial blood pH for primipara. So, one-to-one labor support could be applied as an effective nursing treatment for primipara.

• Korean Journal of Community Nutrition
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• v.8 no.5
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• pp.781-793
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• 2003

This study was performed to investigate the stress level and health-related behaviors of nurses and to provide basic information for developing educational programs in the health care field. The subjects of this study were 197 nurses and 94 nursing assistants working at hospitals in the Kyung-nam area. A survey was conducted using a self-administered questionnaire in November, 2002. The results were as follows : The average age and work experience of the subjects were 26.9 and 5.6 years, respectively. The number of respondents in the shift and non-shift operations was equally distributed. The mean height and weight were 161.2 cm and 52.7 kg, respectively. Even though the average body mass index (BMI) and obesity index were normal in the subjects, 9.2% of the subjects were overweight/obese, while 28.9% of the subjects were under weight, according to the obesity index. The mean score of stress was 27.5 \pm$\pm$ 4.6 out of 50 points. Most of the subjects were highly stressed about the amount of their work, problems regarding their future, and relationships with their superiors. With regard to changes in food intake due to stress, 44.1% showed an increased intake, while 32.3% showed a reduced intake. The degree of health consciousness of the married nurses, those over 36 years of age, and those with over 10 years of nursing experience was significantly higher than that of the unmarried nurses, those under 35 years of age, and those with under 10 years of nursing experience (p<0.01). Fifty-one point three percent of the subjects thought their health status was unhealthy. Fifty-seven percent of the subjects had tried weight control. Their main reason for trying weight control was to have a slender figure (62.3%), and their methods of weight control were moderation in intake(45.6%), exercise and dieting (36.9%). TV/radio (49.5%) and newspaper/magazines (47.1%) were the primary sources of nutritional and health information for the subjects, and professional (25.1%) and the internet (13.4%) were ranked relatively highly. The food components of most concern to the subjects during meal time were (in order of importance) fats (51.9%), calories (40.2%) and salt (35.1%). The subjects considered 'taking a rest' (73.5%) as the most important factor in maintaining an optimal health status, followed by self-relaxation (56.4%), moderation in diet (39.5), bathing or using a sauna (25.7%) and exercising (22.7%).

• Journal of Korean Academy of Nursing Administration
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• v.5 no.1
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• pp.149-167
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• 1999

This study was designed and carried out to investigate the effect of Assertiveness Training on the stress response and assertive behavior of emergency room nurses from September 22, to December 21. 1997. The subjects were 45 emergency room nurses of three general hospitals of Korea University Medical Center; 25 assigned for the experimental and 20 for the control group. The Assertive Training Program was composed of cognitive training, behavioral training and progressive muscle relaxation. The subjects of the experimental group carried out the 15-minute progressive muscle relaxation according to recorded-tape once a day for 6 weeks. The cognitive and the behavioural training were conducted by the investigator for 5-8 subjects at a time for 9 series, at an interval of 4-5 days. Post-measurement were administered to all sujects in two groups three weeks after the last session. The level of general stress (Cline, 1992), job stress (Kim & Koo, 1984), physiological response to stress (cortisol, epinephrine, norepinephrine), symptoms of stress (Lee, 1984) and assertive behavior (Kim, 1982) were measured before the first and after the last experiments. Data were analysed by x2, t, paired t, Wilcoxon signed rank tests Wilcoxon rank sums tests. The results are as follows : 1. The level of general stress of the experimental group was lower than that of the control group, however, no significant difference between the two groups (P=0.234) was revealed. 2. A significant reduction of job stress was revealed in the experimental group (P=0.017). 1) A significant reduction of interpersonal conflicts in the experimental group was revealed (P=0.018). 3. The physiological stress-response were analyzed as follows : 1) A decrease of Cortisol in both the experimental and the control groups was noticed, however, the difference between the two groups was not statistically significant (P=0.991). Pre-and post-measurement of the level of Corti sol revealed that a notable decrease in the experimental group and an increase in the control group with no significant difference in the day-day subjects (P=0.765), a significant decrease was noted on the level of Cortisol of the experimental group in the night-night nurses (P=0.036). 2) An increase of Epinephrine in both groups was noticed, however, a difference was not statistically significant between the two groups (P=0.082). Pre-and post-measurement of the level of Epinephrine revealed that a notable decrease in the experimental group and an increase in the control group with no significant difference in the day-day subjects (P=0.136). increases were noted on the level of Epinephrinel of both groups in the night-night nurses (P=0.136), 3) The level of Norepinephrine of the experimental group was significantly decreased (P=0.020). Pre-and post-measurement of the level of Norepinephrine revealed that a notable decrease in the experimental group and an increase in the control group with no significant difference in the day-day subjects (P=0.073). a significant decrease was noted on the level of Norepinephrine of the experimental group in the night-night nurses (P=0.036), 4. Symptoms of stress were reduced in both groups, with no significant differences between the groups (P=0.127). 1) The physical stress symptoms were reduced in both groups, with no significant difference (P=0.386), 2) The cognitive-behavioral stress symptoms were significantly reduced in the experimental group (P=0.037). 3) The emotional stress symptoms were reduced in both groups with no significant difference between the groups (P=0.110). 5. The assertive behavior was significantly increased in the experimental group (P=0.000). This study signified the Assertiveness Training as an effective mean of self intervention for the reduction of stress of nurses assigned to emergency rooms.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.94.2-94.2
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• 2010

Indium tin oxide (ITO) Thin films were grown on Non-alkarai glass Substrates by PVD method and Subsequently Subjected to ($100^{\circ}C-350^{\circ}C$) Thermal Annealing (TA) In Nitr Oxygen ambinent. Most of all, The effect of TA treatment on the structural properties were studied by using X-Ray diffraction and atomic force microscopy, while optical properties were studied by UV-Transmittance measurements. After TA treatment, the XRD spectra have shown an effective relaxation of the residual compressive stress, As a result, XRD peaks increase of the intensity and narrowing of full width at half-maximun (FWHM). In addtion The microstructure, The surface morphology, the optical transmittance changed and improved, and we investigated The effects of temperature, Time and atmosphere during the TA on the structural and electrical properties of the ITO/glass on TA at $300^{\circ}C$. As a results, the films are highly transparent (80%～89%) in visible region. AFM analysis shows that the films are very smooth with root mean square surface roughness 0.58nm -2.75nm thickness film. It is observed that resistivity of the films drcreases T0 $1.05{\times}10^{-4}{\Omega}cmt$ $6.06{\times}10^{-4}{\Omega}cm$, while mobility increases from $152cm^2/vs$ to $275cm^2/vs$.

• Steel and Composite Structures
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• v.33 no.6
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• pp.777-792
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• 2019

This paper presents a new efficient approach to estimate the S-N type fatigue life assessment curve for S550 high strength steels under low-cycle actions at -60℃. The proposed approach combines a single set of monotonic tension test and one set of fatigue tests to determine the key material damage parameters in the continuum damage mechanics framework. The experimental program in this study examines both the material response under low-cycle actions. The microstructural mechanisms revealed by the Scanning Electron Microscopy (SEM) at the low temperature, furthermore, characterizes the effect due to different strain ratios and low temperature on the low-cycle fatigue life of S550 steels. Anchored on the experimental results, this study validates the S-N curve determined from the proposed approach. The S-N type curve determined from one set of fatigue tests and one set of monotonic tension tests estimates the fatigue life of all specimens under different strain ratios satisfactorily.

• Journal of Oriental Neuropsychiatry
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• v.25 no.1
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• pp.1-12
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• 2014

Objectives: In this study, the meditation programs (${\alpha}$ version), which are properly coordinated according to the motion, breathing, and relaxation, are evaluated and researched upon to have positive effects on stress and in the area of psychology. Methods: Approved by the Clinical Trials Deliberation Committee in Oriental Medicine, Dongguk University, Ilsan Hospital, this study collected data according to the applicant's consents, demographic information and anthropometry for the Sasang Constitutional diagnosis. Sasang Constitutional diagnosis measured the beta tools by Institute of Oriental Medicine and a decision tree was made for the Sasang Constitutional questionnaires. The STAI, STAXI, BDI, and HRV were measured before and after the meditation in order to compare the effects of meditation according to Sasang Constitution. The HRV was used as a ProComP KM Tech (co). Results: 1) The positive changes available in the Time-domain analysis of heart rate variability assessment showed that the peace of mind is increased. By analyzing the Sasang constitution, So-eum In's peace of mind included a physical stability of the autonomic nervous system. 2) According to the psychological scale evaluation, each depression scale, trait anger, anger-in, state anxiety and trait anxiety index proved significantly positive effects. By analyzing the Sasang constitution, Eun-In which involved So-eum In and Tae-eum In, had positive effects. 3) The psychological scale changed the group of diagnosed depression or anxiety, it did not mean that the psychological scale changes in the depression group, but the index of the anxiety group had been significantly reduced. This program had clinical effects for anxious patients and Eum-In which involved Tae-eum In and So-eum In according to the analysis of Sasang constitution. 4) Correlations between the gender of each psychological scale showed that women have overall low correlations, but, there were no significant changes. Conclusions: The meditation program developed by adequately mixing Action, relaxation and breathing shows that it is effective for overall Eum-in physical and mental relaxation and concentration. In the future, It will have to be developed Meditation program to show the same effect for all people.