• Steel and Composite Structures
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• v.50 no.5
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• pp.499-513
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• 2024

This paper describes the experimental and numerical investigations of octagonal Concrete-Filled Double Skinned Steel Tube (CFDST) short columns under the influence of various internal sizes of the circular and square steel tubes, with constant cross-sectional dimensions of the external octagonal steel tube under concentric loading. The non-linear finite element analysis of octagonal CFDST columns was executed using the ABAQUS to forecast and compare the axial compression behavior influenced by the various sizes of internal circular and square steel tubes. The study shows that the axial compressive strength and ductility of octagonal CFDST columns were significantly influenced by various internal dimensions of the circular and square steel tubes with the strengths of constituent materials.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.62-69
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• 1998

Spiral tube heat exchangers can find numerous applications in many engineering field. Flow in spital tubes is interest to engineers due to occurrence of secondary flow which enhances the cross-sectional mixing and the heat transfer rate. In the present study, an incompressible viscous 3-D flow in spiral tubes with rectangular cross-section of various torsion rate and Reynolds number is studied by using a finite volume method. It is shown that the axial velocity profile is affected by the secondary flow motion. Because there is some difference from correlation proposed by Hur et al., a lot of analysis and arrangement of experimental results are needed. This study showed the results of variation of hydrodynamic entry length for torsion and Re numbers.

• Restorative Dentistry and Endodontics
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• v.30 no.2
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• pp.95-101
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• 2005

The aim of this study was to evaluate the microleakage of teeth according to root canal preparation with & without apical enlargement in various size of apical foramen. 60 extracted one canal roots were cross-cutted at 5 mm from root apex and divided into two groups according to their apical foramen size of large (L) and small (S). Each group was subdivided into two groups accordance with their cross-sectional configuration at 5 mm from apex, round (R) and ovoid (O); SR Group, SO Group LR Group, LO Group. Each group was shaped in .02 taper by Quantec series Nickel-Titanium (NiTi) rotary file, obturated by lateral condensation method. Leakage was measured using a fluid transport model under 40 $cmH_2O$ pressure. After the leakage test, blocks which had showed the leakage retreated with .04 taper and ,06 taper and evaluated the degree of fluid filtration in each group. The data was analysed statistically using chi-square test and fisher's exact test. The results obtained were as follows : 1. Significant difference in leakage was found in groups which had different apical foramen size in .02 taper instrumentation (p < 0.05), but not in .04 taper instrumentation (p > 0.05) 2. The difference in microleakage according to the shape of canal was not evident at 5 mm from apex (p > 0.05). 3. There was correlation between .02 taper instrumentation and .04 taper instrumentation in LR group, LO group (p < 0.05).

• Journal of Preventive Medicine and Public Health
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• v.57 no.3
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• pp.242-251
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• 2024

Objectives: The aim of this study was to analyze the relationship between objective social isolation (SI) and unmet medical needs (UMN) in adults aged 19 and older. Methods: A cross-sectional analysis was conducted of 208 619 adults aged 19 and older, excluding missing data, using the 2019 Korea Community Health Survey. To analyze the association between objective SI and UMN, the chi-square test and logistic regression analysis were performed. Results: The prevalence of UMN was 1.14 times higher (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.06 to 1.23) among those with SI than among those without SI, and the OR for groups with 5 SI types was 2.77 (95% CI, 1.86 to 4.12) compared to those with no SI types. In addition, a stratified analysis by age group showed that the association between SI and UMN existed even in groups under 64 years old. However, among those aged 65 and older, SI was associated with an OR of 1.53 (95% CI, 1.37 to 1.71) for UMN compared to non-SI. As the number of SI types increased, the prevalence of UMN also increased, indicating a strong association between SI and UMN in older adults. Conclusions: This study found that individuals with SI experienced UMN due to fear and anxiety about interpersonal relationships. Therefore, based on the results of this cross-sectional study, it is necessary to investigate the causal relationship between SI and UMN through future longitudinal data.

• The Journal of Korean Medicine
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• v.39 no.2
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• pp.80-91
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• 2018

Objectives: The purpose of this study was to investigate stress and health recognition in Korean medical student by gender. Methods: 393 Korean medical student participated in this study. They were surveyed demographic characteristics(gender, age, drinking, morning diet, health recognition and etc), medical stress scale, Maslachh burnout inventory, Korea acceptance and action, and Ego Resilience Scale. For statistical analysis, chi-square test, Student t-test, correlation analysis, and simple regression analysis has been used. Results: In Medical stress scale and ego resilience, it is not significant difference by gender. Female students were significantly higher than male students in Maslach burnout inventory(P=0.015). Male students were significantly higher than female students in Korea Acceptance and Action(P=0.002). Health recognition have negative correlation between medical stress and academic exhaustion, and positive correlation between psychological flexibility and ego resilience. Conclusions: Through these results, we need to further study and develop strategies to reduce stress according to gender in Korean medical college.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6385-6388
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• 2013

Background: Smokeless tobacco consumption is one of the causes of oral cancer. The aim of this study was to determine the prevalence of smokeless tobacco consumption among male students of Zahedan universities and associated factors in 2012. Materials and Methods: In this cross-sectional study, 431 students were selected from the universities of Zahedan using multi-stage random cluster sampling. The data collection tool was a questionnaire including questions about demographic information, history of smokeless tobacco consumption, and awareness of smokeless tobacco hazards. Data were analyzed by SPSS19 using Chi-square test and multinomial logistic regression, with p<0.05 considered significant. Results: At the time of conducting this study, 102 students (23.7%) had already consumed smokeless tobacco and 49 students (11.4%) were current users (consuming at least once in 30 days before the study). There was a significant relationship between history of smokeless tobacco consumption, university/college, place of living, mean GPA, and mother's education level (p<0.05). Also there was a significant association between knowledge and prevalence of smokeless tobacco use (p<0.001). Conclusions: There is a relatively high prevalence of smokeless tobacco consumption among the male students of universities of Zahedan, which shows the need to emphasize the provision and implementation of prevention programs in universities.

• Journal of Preventive Medicine and Public Health
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• v.52 no.2
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• pp.109-114
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• 2019

Objectives: The purpose of this study was to characterize Indonesian women's knowledge of HIV/AIDS and to investigate the effects of socio-demographic characteristics thereupon with the goal of supporting the prevention and early detection of HIV/AIDS. Methods: This cross-sectional study was conducted using secondary data from the standard Indonesian Demographic and Health Survey (IDHS) in 2012. A total of 34 984 subjects ranged in age from 15 years to 49 years. Data were analyzed using the chi-square test and logistic regression to identify the effects of socio-demographic characteristics on Indonesian women's knowledge of HIV/AIDS. Results: All socio-demographic characteristics except marital status were related to knowledge of HIV/AIDS among Indonesian women in the univariate analysis (p<0.05). Multivariate analysis revealed that only age group, education level, location of residence, and wealth index were related to Indonesian women's knowledge of HIV/AIDS (p<0.05). Conclusions: Indonesian women's insufficient knowledge related to HIV/AIDS shows that the provision of accurate and comprehensive information related to HIV/AIDS are components of prevention and control interventions that should be improved. With greater knowledge, women are expected to be more likely to determine their own and their partners' human immunodeficiency virus status and to take appropriate preventive steps.

• Computers and Concrete
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• v.23 no.4
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• pp.281-294
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• 2019

The post-fire behavior of structural elements and the cooling process has always been one of the main concerns of the structural engineers. The structures can be cooled at different rates, where they affect the structure's behavior. In the present study, a numerical model has been developed using the Abaqus program to investigate the effect of cooling rate on the post-fire behavior of the CFST column. To verify the model, results of an experimental study performed on CFST columns within a full heating and cooling cycle have been used. In this model, coMParison of the residual strength has been employed in order to examine the behavior of CFST column under different cooling rates. Furthermore, a parametric study was carried out on the strength of steel and concrete, the height of the specimens, the axial load ratio and the cross-sectional shape of the specimen through the proposed model. It was observed that the cooling rate affects the behavior of the column after the fire, and thus the higher the specimen's temperature is, the more effect it has on the behavior. It was also noticed that water cooling had slightly more residual strength than natural cooling. Furthermore, it was recognized from the parametric study, that by increasing the strength of steel and concrete and the load ratio, as well as modifying the cross-sectional shape from circular to square, residual strength of column at the cooling phase was less than that of the heating phase. In addition, with reducing column height, no change was witnessed in the column behavior after the cooling phase.

• Child Health Nursing Research
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• v.30 no.2
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• pp.97-107
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• 2024

Purpose: This study aimed to investigate the impact of family resilience on caregiver well-being across various age groups of children diagnosed with ADHD (attention-deficit/hyperactivity disorder) groups (0-5, 6-11, and 12-17 years). Methods: Utilizing secondary data from the 2022 US National Survey of Child Health, this cross-sectional study involved 2,752 children who were formally diagnosed with ADHD. Statistical analysis included descriptive analysis, Spearman's rank correlation, chi-square tests, and linear regression, conducted using SPSS version 27. Results: The study revealed a moderate positive correlation (r=.35, p<.001) between family resilience and caregiver well-being. Controlling for covariates, family resilience accounted for 25.2%, 21.1%, and 22.1% of caregiver well-being variance in age groups 0-5, 6-11, and 12-17 years, respectively. Additionally, factors like employment status, family structure, and caregiver age showed varying influences on caregiver well-being across these developmental stages. A consistent pattern emerged across these age groups: unemployment and non-traditional family structures were associated with negative impacts on caregiver well-being, whereas older caregiver age positively influenced well-being. Conclusion: This research underscores the importance of age-specific family resilience strategies to improve caregiver well-being and family interactions in ADHD contexts. Investigating these aspects through qualitative studies across various cultures could deepen our understanding of well-being and inform culturally sensitive interventions.

• Restorative Dentistry and Endodontics
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• v.49 no.2
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• pp.16.1-16.10
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• 2024

Objectives: This cross-sectional study evaluated the prevalence of apical periodontitis (AP) and the technical quality of root canal fillings in an adult Kuwaiti subpopulation using cone-beam computed tomography (CBCT) images. Materials and Methods: Two experienced examiners analyzed 250 CBCT images obtained from Kuwaiti patients aged 15-65 years who attended government dental specialist clinics between January 2019 and September 2020. The assessment followed the radiographic scoring criteria proposed by De Moor for periapical status and the technical quality of root canal filling. Chi-square and Fisher's exact tests were used for statistical analysis, with significance level set at p < 0.05. Results: Among the 2,762 examined teeth, 191 (6.91%) exhibited radiographic signs of AP, and 176 (6.37%) had undergone root canal filling. AP prevalence in root canal-treated teeth was 32.38%, with a significant difference between males and females. Most of the endodontically treated teeth exhibited adequate root canal filling (71.5%). Conclusions: The study demonstrated a comparable prevalence of AP and satisfactory execution of root canal treatment compared to similar studies in different countries.