• Journal of the Korean Society of Safety
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• v.16 no.1
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• pp.79-83
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• 2001

Posture of the upper limbs in field works is known to be an important risk factor associated with CTD(Cumulative Trauma Disorders). In particular, uncomfortable posture and highly repetitive works in shipbuilding industry(for instance, sand blasting, grinding and blast painting, etc) made workers exposed to a great risk of injuries. The purpose of this paper is to analyze recruitment pattern of the muscles according to posture(joint angle displacement) during grinding. In this study, EMG signals of pectoralis major, latissimus dorsi, and posterior deltoid muscle were measured and analyzed from FlexComp EMG solution. And subjective ratings of perceived exertion were made using Borg's CR-10 rating scale.

• Journal of Environmental Science International
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• v.25 no.7
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• pp.951-961
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• 2016

To prevent increasing instances of heat-related illnesses due to heat waves generated by climate change, a customized thermal environment index should be developed for outdoor workers. In this study, we conducted sensitivity analysis of the Masan harbor during a heat wave period (August 9th to 15th, 2013) using the MENEX model with metabolic rate and clothing-insulation data, in order to obtain realistic information about the thermal environment. This study shows that accurate input data are essential to gather information for thermophysiological indices (PST, DhR, and OhR). PST is sensitive to clothing insulation as a function of clothing. OhR is more sensitive to clothing insulation during the day and to the metabolic rate at night. From these results, it appears that when exposed to high-temperature thermal environments in summer, wearing highly insulated clothing and getting enough rest (to lower the metabolic rate) can aid in preventing heat-related illnesses. Moreover, in the case of high-intensity harbor work, quantification of allowed working time (OhR) during heat waves is significant for human health sciences.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.33-40
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• 2012

Dentists are known to be highly exposed to the musculoskeletal disorders (MSD). The present study investigated the prevalence of MSD among Korean dentists and association between their MSD and physical workload. In addition, detailed causes related to the physical workloads were identified in dental operation, and needs for improvement of dental instrument and environment were collected from Korean dentists. The standardized Nordic questionnaire was used to survey body troubles and three types of questionnaires were made to investigate the physical workloads, causes of the physical workloads and improvement priority of dental equipments, respectively. A total of 104 Korean dentists were participated in the survey. Neck trouble (82%) was the most prevalent in Korean dentists, and shoulder (68%) and low back trouble (56%) followed, while low back trouble was reported to be most frequent in previous studies. The body troubles were related to the physical workload of the corresponding body parts, although they were not associated with personal characteristics. Most Korean dentists selected 'to keep direct view inside patient's mouth' and 'no support of the hand with dental instruments' as the causes of awkward and strenuous work postures. They wanted design improvement for some equipment in their operating room such as operating light and arrangement of workplace.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.561-572
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• 2018

Female tollgate workers are known to be the most highly exposed to job stress in the service industry. However, there have been few studies on female tollgate workers. This study was thus performed to verify the mediator effect of work-family conflicts in the relationship between job stress and turnover intention of female tollgate workers. A survey was carried out in May, 2016, and the final data were obtained from 183 female tollgate workers by quota sampling. The major result was that their job stress significantly influenced on turnover intention, and work-family conflicts between the two variables were partially mediated. On the basis of the outcomes, first, further studies are needed to develop customized supporting programs for the female tollgate workers; second, internal efforts, such as psychological and social support programs such as Employee Assistance Programs (EAPs), should be launched for the workers at the enterprise level; third, national attention must be paid to improve the work environments of female tollgate workers.

• Journal of Preventive Medicine and Public Health
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• v.53 no.6
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• pp.429-438
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• 2020

Objectives: Given that Argentinian public-sector workers are highly exposed to stressful conditions, and that the psychometric properties of the widely used Perceived Stress Scale (PSS) should be evaluated in different settings, this work aimed to compare the psychometric properties of the Latin American Spanish PSS-10 and PSS-4 and to identify the optimal scale for stress assessment. Methods: A sample of 535 participants was randomly divided into 2 groups to evaluate dimensionality by exploratory and confirmatory factor analyses. The reliability of both scales was also evaluated. Convergent validity was estimated using the Executive Complaints Questionnaire, the average variance extracted, and the composite reliability. Discriminant validity was based on the correlation with the Utrecht Work Engagement Scale and the phi-square correlation between the components. Results: The factor analyses supported bidimensionality of the PSS-10 (stress and coping), which showed a better fit than the PSS-4. Moreover, the reliability of the PSS-10 was higher, whereas the PSS-4 did not achieve adequate values of internal consistency. The PSS-10 was also correlated significantly with all validation scales, and presented proper internal convergent and divergent validity. Conclusions: The PSS-10 is a reliable and structurally valid instrument to measure perceived stress and coping in a Latin American Spanish-speaking population with high work demands, and the findings of this study expand our knowledge on the geographical and sociocultural applicability of the PSS.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.137-147
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• 2007

Dentists are known to be highly exposed to the musculoskeletal disorders (MSD). The present study investigated the prevalence of MSD among Korean dentists and association between their MSD and physical workload. In addition, work-related causes of high physical workload were identified and needs of dentists were collected for improvement of dental instrument and environment. Four types of questionnaires including the Nordic questionnaire were used to investigate body troubles, physical workload, causes of physical workload, and improvement priority of dental components. A total of 104 dentists in Seoul were participated in the survey. Neck trouble (82%) was the most prevalent in the participated dentists and shoulder (68%) and low back trouble (56%) followed, while low back trouble was reported to be most common in previous western studies. The body troubles were related to the physical workload of the corresponding body parts, although they were not associated with personal characteristics. Most dentists selected 'to keep direct view inside patient's mouth' and 'no support of the hand with dental instruments' as causes of awkward and strenuous work postures. They wanted design improvement for some components in their operating room such as operating light and arrangement of workplace.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.2
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• pp.264-271
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• 1998

A pilot study was undertaken to examine the possible health effects of electromagnetic fields(EMFs). The purpose of this study was to investigate of the EMFs exposures of personal environment, 60Hz magnetic fields. An experimental study was performed for six weeks of January-February 1998 to compare changes in melatonin levels in urine of 20 subjects during their normal sleeping hours and each 20 subjects in occupational and non-occupational group measured personal 24-h continual exposure, using EMDEX II (for 40-800Hz, Enertech Consultant, Inc.). An urine samples were collected 3 times a day(before sleep or around 24:00 ; immediately after wake-up ; around noon) for an week from each subjects and analyzed by radioimmunoassay. This study did not significant difference for the subjective average melatonin levels between occupational and nonoccupational groups exposed to electromagnetic fields. The mean personal exposure levels of occupational group were $0.215{\mu}T$, whereas non-occupational group were $0.18{\mu}T$. Occupational group were exposed more highly while at work. Finally, this study would provide significant data for furture study of exposure assessment of magnetic fields. A large scale study concerning more detailed exposure assessment should provide important information on health risk assessment of MFs. Further study should provide information on the contribution of various sources and the relationship between melatonin and immune system activity.

• Environmental Analysis Health and Toxicology
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• v.29
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• pp.2.1-2.7
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• 2014

Objectives Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone important in the maturation of a broad spectrum of protein. In this study, an HSP90 gene was isolated from Asian paddle crab, Charybdis japonica, as a bio-indicator to monitor the marine ecosystem. Methods This work reports the responses of C. japonica HSP90 mRNA expression to cellular stress by endocrine disrupting chemicals (EDCs), such as bisphenol A (BPA) and 4-nonylphenol (NP) using real-time. reverse transcription polymerase chain reaction. Results The deduced amino acid sequence of HSP90 from C. japonica shared a high degree of homology with their homologues in other species. In a phylogenetic analysis, C. japonica HSP90 is evolutionally related with an ortholog of the other crustacean species. The expression of HSP90 gene was almost distributed in all the examined tissues of the C. japonica crab but expression levels varied among the different body parts of the crabs. We examined HSP90 mRNA expression pattern in C. japonica crabs exposed to EDCs for various exposure times. The expression of HSP90 transcripts was significantly increased in C. japonica crabs exposed to BPA and NP at different concentrations for 12, 24, 48 and 96 hours. The mRNA expression of HSP90 gene was significantly induced in a concentration- and time-dependent manner after BPA or NP exposures for 96 hours. Conclusions Taken together, expression analysis of Asian paddle crab HSP90 gene provided useful molecular information about crab responses in stress conditions and potential ways to monitor the EDCs stressors in marine environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.259-266
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• 2011

Femtocells are expected as the surest way to increase the system capacity with higher-quality links and more spatial reuse in future networks. In spite of their great potential, the system capacity is highly susceptible to network density because a large portion of users are exposed to inter-cell interference (ICI). In this work, we proposed a dynamic interference avoidance scheme in densely deployed cell environments. Our proposed DDIA (Distributed Dynamic ICI Avoidance) scheme not only works in a fully distributed manner, but also controls interference link connectivity of users with high agility so that it is suited for self-organizing networks (SONs). We introduced the concept of ICI-link and two-tier scheduling in designing the DDIA scheme. To avoid ICI without any central entity, our scheme tries to harmonize all base stations (BSs) with users adaptively. Through extensive simulations, it was shown that our proposed scheme improves the throughput of users by more than twice on average compared to the frequency reuse factor 1 scheme, who are exposed to ICI while maintaining or even improving overall network performance. Our scheme operates well regardless of network density and topology.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.553-559
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• 2022

In this work, the ablation behavior of monolith ZrB₂-30 vol%SiC (Z30S) composites were studied under various oxy-acetylene flame angles. Typical oxidized microstructures (SiO₂/SiC-depleted/ZrB₂-SiC) were observed when the flame to Z30S was arranged vertically. However, formation of the outmost glassy SiO₂ layer was hindered when the Z30S was tilted. The SiC-depleted region was fully exposed to air with reduced thickness when highly tilted. Traces of the ablated and island type SiO₂ were observed at intermediate flame angles, which clearly verified the effect of flame angle on the ablation of the SiO₂ layer. Furthermore, the observed maximum surface temperature of the Z30S gradually increased up to 2,200 ℃ proving that surface amorphous silica was continuously removed while monoclinic ZrO₂ phase began to be exposed. A proposed ablation mechanism with respect to flame angles is discussed. This observation is expected to contribute to the design of complex-shaped UHTC applications for hypersonic vehicles and re-entry projectiles.