• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.1.1-1.13
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• 2022

Background: Recently, there has been a call to improve the holistic welfare of dependent contractors (DCs). Thus, our study examined the relationship between DCs and mental health symptoms and how this relationship was modified by age, sex, and income status of workers. Methods: A total of 27,980 workers from the Fifth Korean Working Conditions Survey are included in our study. The participants who reported having depression or anxiety over the last 12 months are defined those who had mental health symptoms. We performed exact matching for age group and sex, followed by conditional logistic regression with survey weights. Finally, stratified analyses by age, sex and income level were conducted. Results: DCs were found to be at increased risk of depression/anxiety compared to other workers. The odds ratio (OR) is 1.52 (95% confidence interval [CI]: 1.06-2.17). In the stratified analyses, vulnerable groups were middle-aged (OR [95% CI]: 1.68 [1.10-2.54]), female (OR [95% CI]: 1.85 [1.20-2.84]), and low-income (OR [95% CI]: 3.18 [1.77-5.73]) workers. Conclusions: Our study's results reinforce those of other studies that show that DCs are at greater risk of experiencing mental health issues than other workers and that and this risk is greater for middle-aged, female, and low-income workers. These results suggest that appropriate policy efforts should be made to improve the psychological well-being of DCs.

• International Journal of Heart Failure
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• v.6 no.2
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• pp.84-90
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• 2024

Background and Objectives: Vitamin D, as a steroid hormone, has multiple effects on human body and its deficiency has been associated with an increased risk of heart failure (HF) and unfavorable outcomes. The present study investigated the prevalence of vitamin D deficiency (VDD) and its relationship with cardiometabolic parameters in patients hospitalized for HF living in the city of Recife (latitude 8° South). Methods: Analytical cross-sectional study, with men and women aged 40-64 years. The HF group was recruited during hospitalization due to decompensation. A matched control group was recruited from the general endocrine clinics. Vitamin D status was assessed by measuring serum 25-hydroxyvitamin D (25OHD), considering deficiency when 25OHD <20 ng/mL (<50 nmol/L). Results: A total of 243 patients were evaluated (HF group: 161, control group: 82). Lower serum 25OHD levels were observed in the HF group (25.2±9.4 vs. 30.0±7.7ng/mL; p<0.001), as well as a higher prevalence of VDD (27.3% vs. 9.8%; prevalence ratio, 2.80; 95% confidence interval, 1.38-5.67; p=0.002). In patients with HF, VDD was associated with diabetes mellitus (65.9% vs. 41.0%; p=0.005) and female sex (65.9% vs. 44.4%; p=0.015). In the subgroup with VDD, higher values of hemoglobin A1c (7.9% [6.0-8.9] vs. 6.2% [5.7-7.9]; p=0.006) and dyslipidemia were also observed. Conclusions: We found higher rates of VDD in patients hospitalized for HF and this was associated with deleterious laboratory metabolic parameters.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.443-451
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• 1999

Objective: To examine the relationship between hypertension prevalence and the four commonest anthropometric measurements for obesity(body mass index(BMI), wasit-hip ratio(WHR), waist circumference(WC) and body fat in Korean adults. Methods: We studied the cross-sectional association of the anthropometric indices and blood pressure in 1,197 individuals(who were participants in the population-based cohort study). Hypertension was defined as blood pressure $\geq160/95\;mmHg$ or current use of antihypertensive medication. Informations on life-style factors were obtained from personal interview. Results: There were close associations between BMI, WHR and WC with blood pressure in both men and women. After age adjustment, BMI and WC showed significantly positive correlation with systolic and diastolic blood pressure levels in both men and women. Odds ratio(ORs) of being hypertensive were estimated comparing the highest to the lowest quantile, adjusting for age, smoking status, alcohol intake levels, education attainment. The simultaneously adjusted ORs of being hypertensive, comparing the highest vs the lowest categories, was for BMI 2.0(95% confidence interval(CI)=0.9-3.2) in men and 3.2 (95% CI=1.7-6.1) in women, for WC 2.1(95% CI=1.0-4.4) in men and 3.1 (95% CI=1.6-5.9) in women, for fat(%) 4.2(95% CI=1.9-9.5) in men and 2.1(95% CI=1.2-3.6) in women. Conclusion: In addition to measures of overall obesity(BMI) as well as central obesity(WHR, WC), body fat(%) was independently associated with prevalence of hypertension. Among obesity indices, body fat was the most predictor variable in hypertensive state in male and BMI was in female.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.505-512
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• 1999

Objectives : The purpose of this study was to assess the relationship between job strains and absenteeism from work. Methods : The study design was cross-sectional, and the study subjects consisted of 1,166 workers who were employed in the small-sized industries. A self administered questionnaire was used to measure the general characteristics, job characteristics(job demand, job control), and social support(coworker support, supervisor support) at work. The Job Content Questionnaire(JCQ) was used to assess job demand(2 items) and decision lattitude(10 items). Social support at work (10 items) was measured using JCQ. Sick absence was collected using self-report and were rechecked by the attendance record of their company. Odds ratios and 95% confidence intervals for the association between job strain and sick absence were estimated. The modifying effect of social support was evaluated by stratification. Logistic regression was used to estimate the relationship between job strain and sick absence. Results : In the bivariate analysis, the variables related to sick absence were age, marital status, occupation, job demand. Four distinctly different kinds of level of job strain were generated by the combination of job demand and job control: low strain group, high strain group, active group, and passive group. The crude odds ratio of high job strain was 1.78(95% CI: 1.26-2.53), and those of active group and passive group were 1.33(95% CI: 1.07-1.66) and 1.13 (95% CI: 0.88-1.47), respectively. The odds ratio of high job strain after adjusting for age and occupation were still significant The odds ratio of high job strain in low social support was 5.96(95% CI: 2.45-14.51), but that in high social support was 0.73(95% CI: 0.26-2.01). Conclusions : Job strain was associated with increased risk of absenteeism from work, and social support at work modified the association between job strain and sick absence.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.127-131
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• 2002

We fabricated MTJ devices that have doubly oxidized tunnel barrier using plasma oxidation method to from oxidized AlO$\sub$x/ tunnel barrier. Doubly oxidation I, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it with oxidation time of 10 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 50, 80 and 120 s., respectively. Doubly oxidation II, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it varying oxidation time for 30∼120 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 210 sec. Double oxidation process specimen showed MR ratio of above 27％ in all experiment range. Singly oxidation process. 13 ${\AA}$-Al layer and oxidized up to 210 s, showed less MR ratio and more narrow process window than those of doubly oxidation. Cross-sectional TEM images would that doubly oxidized barrowers were thinner and denser than singly oxidized ones. XPS characterization confirmed that doubly oxidation of Fe with bottom insulating layer. As a result, doubly oxidation could have superior MR ratio in process extent during long oxidation time because of preventing oxidation of bottom magnetic layer than singly oxidation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2A
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• pp.75-83
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• 2012

In this study, an analytical studies were carried out for the buoyancy preflexion method to improve structural performance of concrete floating structures. The buoyancy preflexion means that the preflexion effects were induced to the floating structure due to the difference in buoyancy between the pontoon modules composing the floating structures. In order to verify the buoyancy preflexion effects, an analytical studies were carried out for the floating structures. The size and dimensions of FE model were determined through the structural design process. The parameter of this analytical study was length ratios of central module part, which induces buoyancy preflexion effects, to the total length. The analysis results were pre-compression on the bottom concrete slab and displacement of freeboard due to buoyancy preflexion effects. These results were processed according to the loading step, buoyancy preflexion loads on the bottom and live loads on the topside. Then, the buoyancy preflexion effects on structural performance was analyzed. As the results of this study, it was found that the buoyancy preflexion significantly influence on structural performance of floating structures. According to the length ratio, the buoyancy preflexion effects have a tendency of parabolic form and maximized at the length ratio of 40~60%. The buoyancy preflexion method is simple in principle and easy in application. Also, it can effectively induce pre-compression on the bottom concrete slab. Therefore, it can be concluded that the buoyancy preflexion method contribute to the improvement of structural performance and decreasing of the cross-sectional depth of floating structures.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.277-285
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• 2019

This study was conducted to understand the growth characteristics of Picea jezoensis that was one of representative subalpine species in Korea, in the light of the effects of wind and micro-topography in its habitats on Mt. Deogyu, Korea. The prevailing wind directions were southwest and west at the study sites. We randomly selected P. jezoensis (height ≥ 1.5 m) on windward, intermediate, and leeward slopes and measured diameter at breast height (DBH), height, crown length by 8 directions in upper, middle and lower sectors of the crown. We examined the micro-topography of P. jezoensis stood on and classified it into 3 types: type 1 was mounded and fully exposed to surrounding environments without neighboring trees; type 2 was somewhat wind-protected by surrounding rocks, but no neighboring vegetation; type 3 was on gentle slope or flat where P. jezoensis grew with neighboring trees or shrubs. The ratios of height to DBH, and estimated crown growth to actual crown growth (hereafter crown growth ratio) were compared among the three types of micro-topography on windward, intermediate and leeward sites. The height growth per DBH and crown growth ratio in the upper and middle crowns were the smallest on the windward site, and the highest on the leeward site (p < 0.01). The crown growth ratio on type 1 on the windward site was only 46% of that on type 3 on the leeward site. Although on the same windward slope, trees on type 1 had more deformed crown shapes than that on Type 3, showing asymmetric crown cross-sectional areas. Wind and micro-topography played critical roles on the crown growth of P. jezoensis.

• Resources Recycling
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• v.26 no.2
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• pp.56-65
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• 2017

This study is an experimental study on the corrosion protection performance according to the configuration ratio of the Zn and Al. A metal spraying was used as the arc metal spraying method, a specimen was produced by varying the proportion ratio and coating thickness of the Zn and Al. Experimental methods visually observed to corrosion of the specimen for 1, 3, 7, 15 days was conducted in accordance with the CASS salt spray test. This study has confirmed that the performance of the corrosion protection improved against the increase in the Al content. Further, it was confirmed that excellent perfomance is exhibited when the coating thickness is secured over $80{\mu}m$. In addition, the SEM analysis was performed to observe the cross-sectional shape of the metal spraying specimen after CASS testing. The analysis result showed that the deterioration of the metal spraying coating layer was reduced as the Al content increases.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.61-68
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• 2007

The purpose of this study was to compare the centering abilities of four root canal instrument systems and the amounts of dentin removed after root canal shaping using them. The mesial canals of twenty extracted mandibular first molars having $10-20^{\circ}$ curvature were scanned using X-ray micro-computed tomography (XMCT)-scanner before root canals were instrumented. They were divided into four groups (n = 10 per group). In Group 1, root canals were instrumented by the step-back technique with stainless steel K-Flexofile after coronal flaring. The remainders were instrumented by the crown-down technique with Profile (Group 2), ProTaper (Group 3) or K3 system (Group 4). All canals were prepared up to size 25 at the end-point of preparation and scanned again. Scanned images were processed to reconstruct three-dimensional images using three-dimensional image software and the changes of total canal volume were measured. Pre-and post-operative cross-sectional images of 1, 3, 5, and 7 mm from the apical foramen were com pared. For each level, centering ratio were calculated using Adobe Photoshop 6.0 and image software program. ProTaper and K3 systems have a tendency to remove more dentin than the other file systems. In all groups, the lowest value of centering ratio at 3 mm level was observed. And except at 3 mm level, ProTaper system made canals less centered than the other systems (p < 0.05).

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.633-640
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• 2020

The purpose of this study was to research the prevalence and related factors for the life care of knee osteoarthritis in Koreans agricultural and fishery population. Among the agricultural and fishery population over the age of 50, 816 people were chosen to analyze the prevalence of knee osteoarthritis and the prevalence odds ratio of social demographic or health related factors based on the primitive data of the 5th National Health and Nutrition Examination Survey (2010-2012). The prevalence of knee osteoarthritis was 26.3% and, in demographic terms, female, elders, and individuals with low level of educational attainment and monthly income showed higher prevalence of knee osteoarthritis. In health related factors, nonsmokers and people with higher BMI showed higher prevalence of knee osteoarthritis. The present cross-sectional study showing the prevalence ratio and the prevalence odd ratio revealed a high incidence of knee osteoarthritis in Korean agricultural and fishery populations.