• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.47.1-47.14
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• 2023

Background: This study aimed to examine the impact of chronotype on depressive symptoms and explore the mediating effects of sleep quality, pre-sleep cognitive arousal, and social jetlag in a sample of wage earners. Methods: A total of 3,917 waged workers were surveyed online in July 2022. Logistic regression and mediation analysis were used to assess the relationship between chronotype (morningness, intermediate, and eveningness) and depressive symptoms (Patient Health Questionnaire ≥ 5), and the mediating effects of Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), and Pre-Sleep Arousal Scale (PSAS). All analyses were adjusted for age, education level, income level, marital status, coffee consumption, alcohol consumption, physical activity, occupation, employment status, and working hours to calculate odds ratios (ORs). Results: The chronotypes of all the participants were divided into morningness (4.7%), intermediate (93.5%), and eveningness (1.8%). Multiple logistic regression analysis showed an increased risk of depression in the eveningness chronotype (OR: 2.96; 95% confidence interval [CI]: 1.51, 5.86). Regarding the mediation analysis, ISI mediated 28.44% (95% CI: 16.39-40.5), PSQI for 31.25% (95% CI: 19.36, 43.15), and PSAS-Cognitive Score (PSAS-C) for 23.58% (95% CI: 10.66, 36.50) of the association between chronotype and depressive symptoms. However, social jetlag did not significantly mediate this relationship. (percentage mediated = 0.75%, 95% CI: -3.88, 5.39) Conclusions: Evening chronotypes exhibit an increased risk of depressive symptoms, which ISI, PSQI, and PSAS-C partially mediated. This suggests that interventions to improve sleep quality and maintain adequate sleep habits may effectively prevent and treat depression in employees with an eveningness chronotype.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.531-536
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• 2024

Control drones, which are recently classified as smart agricultural machines in the agricultural field, are striving to build smart control and automatic control systems by combining hardware and software in order to shorten working hours and increase the effectiveness of control in the aging era of rural areas. In this paper, the characteristics of the nozzle dedicated to the control drone were analyzed as a basic study for the establishment of management control and automatic control systems. In order to consider various variables such as the type of various drone models, controller, wind, flight speed, flight altitude, weather conditions, and UAV pesticide types, related studies are needed to be able to present the drug spraying criteria in consideration of the characteristics and versatility of the nozzle. Therefore, to enable the consideration of various variables, flow analysis (CFD) simulation was conducted based on the self-designed nozzle, and the theoretical and experimental values of the droplet distribution were compared and analyzed through water reduction experiments. In the future, we intend to calculate accurate scattering in consideration of various variables according to drone operation and use it in management control and automatic control systems.

• Journal of Preventive Medicine and Public Health
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• v.57 no.1
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• pp.83-90
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• 2024

Objectives: Professional firefighters face various health hazards and are required to maintain both physical and mental fitness to effectively mitigate crises and respond to emergencies. Moreover, the long working hours and shift work of this profession impact sleep quality. This study investigated the quality of sleep and its associated factors among firefighters in Bangkok, Thailand. Methods: This was a cross-sectional study of firefighters affiliated with the Bangkok Fire and Rescue Department, Bangkok Metropolitan Administration, Thailand between January 2023 and March 2023. A cluster random sampling technique was utilized to distribute 600 questionnaires to firefighters in 15 fire stations. The questionnaire addressed demographic, work-related, and environmental factors. Sleep quality was assessed using the Thai version of the Pittsburgh Sleep Quality Index (PSQI). Data analysis involved both descriptive and inferential statistics. Bivariate and multiple logistic regressions were performed. Results: The response rate was 78.7% (n=472), and 44.1% of the firefighters reported poor sleep quality (PSQI score >5). Sleep quality was statistically associated with conflicting family relationships (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1 to 2.9), additional part-time jobs (daytime, OR, 2.4; 95% CI, 1.3 to 4.4; or nighttime, OR, 4.3; 95% CI, 1.1 to 16.7), noisy sleeping areas (OR, 1.7; 95% CI, 1.1 to 2.8), and the availability of adequate bedding (OR, 3.0; 95% CI, 1.8 to 4.9). Conclusions: Poor sleep quality among firefighters was associated with various personal, work-related, and environmental factors. Organizations should promote policies that improve sleep quality through good sleep hygiene practices and facilities.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.2
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• pp.156-165
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• 2024

Objectives: This study aims to identify and analyze the exposure status of welding students in specialized high school welding labratories, compare it with the exposure to welding hazards of industrial workers, and seek to improve the educational environment for youth through domestic and international exposure standards. Methods: This study compares the level of exposure to hazardous factors in a welding laboratory of a vocational high school in Jeollanam-do and a welding process in a general industrial site by measuring the work environment. A 10-question survey was conducted to review the effects of welding hazards on the human body, carcinogenicity information, international (US, UK, France) exposure standards, general characteristics between the two groups, and awareness of occupational health. Results: Exposure to hazardous factors in both groups was below the standards set by MOEL. Specialized high school students were exposed to higher levels than workers, and some hazardous factors exceeded the standards when compared to international exposure standards. During the survey, students were less aware of the hazards of welding, safety and health education, and the need for work environment measurement than workers. Conclusions: For the respiratory protection of students in vocational high school welding labs, it is necessary to create a comfortable training environment. Exposure standards for harmful factors should be strictly applied, such as overseas standards, or exposure should be limited by setting a limit on the number of hours of welding practice per week. In addition, it is necessary to conduct safety and health education for welding students to raise their awareness of the importance of measuring the working environment and wearing appropriate protective equipment.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.26 no.3
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• pp.270-276
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• 2022

Backgrounds/Aims: Thoracic epidural analgesia (TEA) is an established analgesic method in open Kausch-Whipple pancreaticoduodenectomy (KWPD). Although, it can cause hemodynamic instability and neurological complications. Inter pleural analgesia (IPA) is an alternative option. We aim to evaluate the effectiveness of IPA versus TEA after KWPD. Methods: We retrospectively studied the efficacy of IPA against TEA in patients, operated by a single surgeon. The primary outcome was the analgesic efficacy and secondary outcomes were analgesia-related complications, inotrope use, and duration. Results: Forty patients (TEA, 22; IPA, 18) were included. Both groups were well matched for patient characteristics, type, and duration of surgery. TEA was associated with higher analgesia-related complications (n = 8, 36.4% vs. n = 1, 5.6%; p = 0.027). TEA complications included analgesia not working (n = 4), leakage (n = 2), refractory hemodynamic instability (n = 1), and lower limb anaesthesia (n = 1). One patient in the IPA group encountered leakage. TEA was associated with longer inotrope requirement (35 vs. 18 hours; p = 0.047). There was no significant difference in intensive care unit (ITU) admission rate (81.8% vs. 77.8%; p > 0.999), median ITU stay (3 vs. 2 days, p = 0.385), or hospital stay (11 days in both groups). Conclusions: In open KWPD, IPA is not inferior to TEA in its efficacy of pain control. IPA was associated with less analgesia-related complications and shorter inotrope requirements. However, this was a small retrospective study. Larger randomized controlled trials are needed to study the effectiveness of IPA.

• Journal of Korea Port Economic Association
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• v.40 no.2
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• pp.1-20
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• 2024

The purpose of this study is to clarify a safety efficiency of ports in South Korea considering port casualties. The paper conducted a vector auto regression to analyze a cause-and-effect relationship between latent factors and port casualties. Subsequently, the paper evaluated safety efficiency for the ports using an undesirable outputs model. The results implied that the number of workers in the shipping union had a statistical effect on the port casualties. In contrast, the number of workers in the operators and working hours are unrelated to the port casualties. In addition, it was found that Yeosu Gwangyang Port is the most safety efficiency port in South Korea. Based on these results, this paper may provide various policy implications for port operators, developers, and managers.

• Geomechanics and Engineering
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• v.38 no.5
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• pp.477-486
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• 2024

The process of inspecting and replacing cutting tools in a shield tunnel boring machine (TBM) is called cutterhead intervention (CHI) (Farrokh and Kim 2018). Since CHI is performed by a worker who enters the chamber in TBM, the worker is directly exposed to high water pressure and huge water inflow, especially in areas with high ground water levels, causing health problems for the worker and shortening of available working hours (Kindwall 1990). Ham et al. (2022) proposed a method of reducing the water pressure and water inflow by injecting a grout solution into the ground through the shield TBM chamber, and named it the new face grouting method (NFGM). In this study, the TBM mechanical characteristics including the injection pressure of the grout solution and the cutterhead rotation speed were determined for the best performance of the NFGM. To find the appropriate injection pressure, the water inflow volume according to the injection pressure change was measured by using a water inflow test apparatus. A model torque test apparatus was manufactured to find the appropriate cutterhead rotation speed by investigating the change in the status of the grout solution according to the rotation speed change. In addition, to prove the validity of this study, comprehensive water inflow tests were carried out. The results of the tests showed that the injection pressure equal to overburden pressure + (0.10 ~ 0.15) MPa and the cutterhead rotation speed of 0.8 to 1.0 RPM are the most appropriate. In the actual construction site, it is recommended to select an appropriate value within the proposed range while considering the economic feasibility and workability.

• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.86-92
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• 2001

The current study was conducted to elucidate the optimum density of free-ranging ducks in a rice-duck farming system in terms of effects on duck behavior, and growth and yield of rice plants. Four paddy fields were used for this experiment, with 6, 9, 12 and 15 birds per plot, respectively. Ducklings at eight days of age were free ranged in experimental paddy plots (4.0 a each) on the 9th day after the transplantation of rice plants. Ducks were kept in the plot for seventy days, at which point rice plants reached the earing stage. Foraging, moving, working, resting, diving and pecking behaviors of the ducks were observed two times during the experimental period. Also, rice plant growth and yield according to the density of ducks per plot were examined. The foraging and moving behavior of free-ranging ducks in paddy fields for 12 hours during the daytime tended to be longer in the 12-bird plot, and working behavior was significantly (P<0.01) longer in the 12-bird plot than in the other three plots. The resting behavior was significantly (P<0.01) higher in the 9- and 15-bird plots than in the 12-bird plot. The frequency of moving behavior for 6 hours during the daytime in the 15-bird plot tended to be lower than that in the other three plots, but this difference was not significant. The amount of diving and pecking behavior in the 9-bird plot was significantly (P<0.05) higher than that in the other three plots, and the number of hills pecked tended to be higher with increasing of duck density. From thirty days after ducks were introduced to the paddy fields, the length of rice plants tended to be significantly (P<0.05) shorter in high free-ranging density plots as compared to low free-ranging density plots. The number of tillers per hill was not affected by the free-ranging density. The culm length of rice plants was significantly (P<0.05) shorter in the 12- and 15-bird plots than in the other two plots, however, the duck free-ranging density did not affect panicle length. The dry weight of the root of rice plants was increased with high free-ranging density, but there was no such increase in the top parts of the rice plants. The percent of rice plants badly damaged by free-ranging density tended to be lower in the order of 12-, 9-, 6- and 15-bird plots. The number of ears, ripening grains and crop yield per hill of rice plants in the 12-bird plot were significantly (P<0.05) higher than those of the other three plots. Therefore, the yield of each rice plant per 10 a was significantly increased in the 12-bird plot.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.558-565
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• 2012

The purpose of this study was to work related musculoskeletal disorders are a major. Occupational disease of the dental care profession is no exception. The survey was self-reported questionars of 300 dental hygienists that 268 dental hygienists reply to self-reported survey. This study results are as follows: Subjects of research analyzing the degree of physical musculoskeletal disorders pain, shoulder 90.3%, neck 89.2%, leg 83.6%, 81.7% back, hand/wrist/fingers 75.7%, arm/elbow, according to 52.8%. Therefore the work province of the research object people the musculoskeletal disorders appeared different. Generally characteristic was taller dental hygienists lower back pain and were out of less weight, study subjects had neck and arm pain. 29~33 year-old age the shoulder, over the age of 34 the arm/elbow to be high (p<0.05). Working environment to become a career, the more hand/wrist/fingers and the pain increased (p<0.05). The neck, shoulders (p<0.05), arm (p<0.01), waist high in the 3~4 years experience. And leg/foot was in the 1~2 years experience. This increase in working hours had increased pain in the neck but the hand/wrist/finger pain in the small hours of experience in the high pain(p<0.01). Conclusion of the musculoskeletal disorders of the dental hygienists often than the average for this risk is recognized. When it occurs early in treatment can be simple, but time is left to revert to normal when you do not already. Therefore, maintaining proper posture and dental hygienists, pain or fatigue appeared to accumulate immediately treated continued efforts are needed.

• Journal of Korean Dental Hygiene Science
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• v.1 no.2
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• pp.9-19
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• 2018

The purpose of this study was to examine the state of conflicts among dental health care workers. A survey was conducted on 266 dental hygienists and nursing assistants who worked in dental institutions from September 12 to November 13, 2017, and SPSS(statistical package for the social science) version 20.0 was employed to analyze the collected data. The findings of the study were as follows: 1. The most common reason of the dental hygienists for turnover was working hours and heavy workload(24.6%), followed by pay (22.6%), conflicts with dentists(16.0%) and conflicts with colleagues (11.3%). The most dominant reason of the nursing assistants for turnover was pay(31.1%), followed by working hours(24.4%), heavy workload(17.8%), conflicts with dentists(15.6%) and conflicts with colleagues(8.9%). 2. The largest reason for unsuccessful communication with dentists was that heavy workload reduced the opportunity to communicate well(54.5%). The second biggest reason was that they couldn't communicate well though they had the opportunity(24.0%), and the third greatest reason was that they tended to lag behind dentists in terms of professional knowledge(16.9%). 3. The biggest reason for unsuccessful communication among the dental health care workers was that they didn't have a lot of chances to communicate well on account of heavy workload(41.0%). The second largest reason was the differences in professional knowledge(24.9%), and the third greatest reason was that they couldn't communicate well though they had the chance(23.7%). 4. The most dominant reason for conflicts with dentists was the difference in power(24.0%), followed by poor communication skills(22.1%) and a lack of mutual respect(18.1%). But the opinions of the nursing assistants were different from those of the dental hygienists, as they cited poor communication skills as the most common reason, which was followed by the difference in power and a shortage of understanding of each other's work. 5. The most common reason for conflicts among the dental health care workers was a shortage of communication and communication skills(22.9%), and the second most dominant reasons were a lack of mutual respect and poor understanding of each other's work(17.5%), followed by a lack of mutual respect(17.2%). 6. As to the ways of resolving conflicts with dentists, the most common case was making some mutual concessions to compromise (28.9%), followed by delivering opinions through the staff meeting (23.9%), resolving conflicts by candidly exchanging opinions(15.8%), avoiding each other in moderation(11.7%) and following the opinions or assertions of dentists(1.3%). 7. Concerning the conflict resolution methods among the dental health care workers, the most prevalent way was making some mutual concessions to compromise(36.4%), followed by resolving conflicts by candidly exchanging opinions(23.0%) and conveying opinions through the staff meeting(18.5%). 8. Regarding communication among the dental health care workers, the dental hygienists(3.53±.729) considered themselves to be better at communicating than the nursing assistants(3.29±.745) did(p<0.05), and the dental hygienists(3.45±.809) who thought there was respectful treatment among workers who were different in occupational categories found themselves to be better than the nursing assistants(3.21±.952) who had the same thought did(p<0.05). As a result of analyzing whether frequent job-related meetings occurred among the workers whose occupational categories were different, the dental hygienists(3.05±.975) perceived that there were more frequent meetings than the nursing assistants(2.67±.955) did (p<0.01).