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Seong-Sik Cho 4 Articles
Associations of self-rated health, depression, and work ability with employee control over working time
Heejoo Ko, Seong-Sik Cho, Jaesung Choi, Mo-Yeol Kang
Epidemiol Health. 2025;47:e2025036.   Published online July 8, 2025
DOI: https://doi.org/10.4178/epih.e2025036
  • 1,573 View
  • 38 Download
AbstractAbstract AbstractSummary PDF
Abstract
OBJECTIVES
Work-time control (WTC), defined as employees’ ability to influence their work schedules, is a crucial determinant of work-life balance and well-being. This study aims to evaluate the associations between WTC and health-related outcomes among Korean workers and examine potential effect modifications by working hours and shift work status.
METHODS
This study analyzed data from the 2024 wave of the Korean Work, Sleep, and Health Study, a nationwide panel study of workers aged 19 years to 70 years (n=5,195). WTC was measured using a 6-item scale, and participants were categorized into low (≤12) or high (>12) WTC groups. Outcomes included self-rated health (SRH), depression (measured by the Patient Health Questionnaire-9), and work ability (WA; measured by the Work Ability Index). Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for poor SRH, moderate-to-severe depression, and poor WA, adjusting for demographic and occupational variables. Subgroup analyses assessed effect modifications by working hours and shift work.
RESULTS
Higher WTC was associated with lower odds of poor SRH (OR, 0.73; 95% CI, 0.62 to 0.86), moderate-to-severe depression (OR, 0.71; 95% CI, 0.61 to 0.83), and poor WA (OR, 0.62; 95% CI, 0.46 to 0.84). These associations were significant among daytime workers but not shift workers. The protective effects of WTC were attenuated among workers whose working hours exceeding 52 hr/wk.
CONCLUSIONS
Higher WTC is associated with better health and work outcomes, emphasizing its importance for employee well-being. However, its benefits may be limited among shift workers and employees working excessive hours.
Summary
Korean summary
- 근로시간 통제권(WTC)이 높은 근로자는 주관적 건강상태가 더 좋고, 우울 위험이 낮으며, 근로능력이 높은 것으로 나타났다. - 이러한 보호 효과는 주간 근로자에서만 유의하였으며, 근로시간이 주 52시간을 초과할 경우 효과가 약화되었다.
Key Message
- Higher work-time control (WTC) was associated with better self-rated health, lower risk of depression, and improved work ability among Korean workers. - The protective effects of WTC were significant for daytime workers but not for shift workers, and benefits diminished when weekly working hours exceeded 52.
Association between psychosocial safety climate and depression risk among Korean workers
Soo Kyung Cho, Seong-Sik Cho, Maureen F. Dollard, May Young Loh, Mo-Yeol Kang
Epidemiol Health. 2025;47:e2025044.   Published online August 13, 2025
DOI: https://doi.org/10.4178/epih.e2025044
  • 869 View
  • 25 Download
AbstractAbstract AbstractSummary PDF
Abstract
OBJECTIVES
Psychosocial safety climate (PSC) reflects an organization’s commitment to safeguarding workers’ psychological health and safety. While international evidence links low PSC to poor mental health outcomes, its association with depression has not been well established in Korea. This study aimed to examine the relationship between PSC and depression among Korean workers, utilizing a large-scale, population-based survey.
METHODS
We analyzed data from 5,337 wage employees who participated in the fifth wave of the Korean Work, Sleep, and Health Study. Depression was measured using the 9-item Patient Health Questionnaire, and PSC was assessed with a validated 4-item scale. Participants were classified into low-risk, intermediate-risk, and high-risk groups based on their PSC scores. Multivariable logistic regression was conducted to estimate the association between PSC and depression, with stratified analyses performed according to gender, age, and occupational characteristics.
RESULTS
The prevalence of depression increased as PSC scores decreased. Compared to the low-risk group, the intermediate-risk and high-risk PSC groups exhibited 1.19 times and 2.69 times higher risks of depression, respectively, suggesting a clear exposure-response relationship. Stratified analyses indicated that associations were stronger among individuals without union representation or access to occupational health and safety resources.
CONCLUSIONS
These findings underscore the critical role of PSC in workplace mental health. Promoting a high PSC may help reduce depression risk and support mental well-being among workers. Interventions considering vulnerable subgroups are warranted to create psychologically safer work environments in Korea.
Summary
Korean summary
-본 연구에서는 한국 근로자에서 심리사회적 안전풍토(PSC) 점수가 낮을수록 우울 위험이 유의하게 높아짐을 확인하였다. -PSC 중간위험군과 고위험군의 우울 위험은 저위험군에 비해 각각 1.19배, 2.69배 높았다. -연구 결과는 근로자의 정신건강 증진과 국가적 정책 수립을 위해 직장에서의 PSC 강화를 강조한다.
Key Message
-This study demonstrates that lower psychosocial safety climate (PSC) scores are associated with a significantly higher risk of depression among Korean workers. -The risk of depression was 1.19 times higher in the intermediate-risk PSC group and 2.69 times higher in the high-risk PSC group compared with the low-risk group. -Findings highlight the importance of strengthening PSC in workplaces to improve employee mental health and guide national policies.
Association between the safety climate and occupational injury in the Korean working population: a cross-sectional study
Jeehee Min, Tae-Won Jang, Hye-Eun Lee, Mo-Yeol Kang, Seong-Sik Cho
Epidemiol Health. 2024;46:e2024082.   Published online October 1, 2024
DOI: https://doi.org/10.4178/epih.e2024082
  • 8,016 View
  • 149 Download
  • 2 Web of Science
  • 3 Crossref
AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
Preventing occupational injuries remains a significant challenge in Korea. A positive safety climate can contribute to reducing workplace injuries. However, the impact of safety climate on preventing occupational injuries among the Korean workforce has not been adequately explored. Therefore, this study aimed to investigate the relationship between the perceived safety climate and occupational injuries within the Korean working population.
METHODS
This study used baseline data from the Korean Work, Sleep, and Health Study (KWSH). The safety climate was measured using the brief version of the Nordic Safety Climate Questionnaire. Occupational injury was determined by whether injuries or accidents had occurred at workplaces in the past year. Logistic regression analysis was performed to examine the association between the safety climate and occupational injury.
RESULTS
Participants who reported an unfavorable workplace safety climate were more likely to experience occupational injuries. Multiple logistic regression analysis revealed that the adjusted odds ratio (OR) for occupational injuries in an unfavorable safety climate was 2.20 (95% confidence interval [CI], 1.38 to 3.51) compared to a favorable safety climate. Specifically, factors such as “not encouraging employees to follow safety rules when on a tight schedule” (OR, 2.02; 95% CI, 1.25 to 3.24) and “not helping each other work safely” (OR, 1.98; 95% CI, 1.17 to 3.25) were significantly associated with occupational injuries.
CONCLUSIONS
An unfavorable safety climate was associated with increased occupational injuries among Korean workers. Improving the safety climate in the workplace may reduce occupational injuries in Korea.
Summary
Korean summary
한국 노동인구집단에서도 안전풍토는 직업성 손상과 관련성이 관찰되었다. 이 같은 결과는 작업장의 안전풍토를 개선함으로써 직업성 손상을 예방할 수 있음을 시사한다.
Key Message
Safety climate was related to occupational injuries in the Korean working population. This result may indicate that occupational injuries can be prevented by improving the workplace safety climate. Workplace safety should be a high priority goal for management, and workers need to help each other for workplace safety.

Citations

Citations to this article as recorded by  
  • Data profile: Korean Work, Sleep, and Health Study (KWSHS)
    Seong-Sik Cho, Jeehee Min, Heejoo Ko, Mo-Yeol Kang
    Ann Occup Environ Med.2025; 37: e3.     CrossRef
  • Safety Climate and Occupational Injuries in the Iron and Steel Industries in Tanzania
    Saumu Shabani, Bente Elisabeth Moen, Teferi Abegaz, Simon Henry Mamuya
    International Journal of Environmental Research and Public Health.2025; 22(9): 1372.     CrossRef
  • Association between safety climate, safety participation, safety compliance, and occupational injuries among workers in large-scale building construction projects in Ethiopia
    Teferi Abegaz, Wakgari Deressa, Bente E. Moen
    International Archives of Occupational and Environmental Health.2025; 98(7): 685.     CrossRef
The physical activity paradox in relation to work ability and health-related productivity loss in Korea
Heejoo Ko, Dohwan Kim, Seong-Sik Cho, Mo-Yeol Kang
Epidemiol Health. 2023;45:e2023096.   Published online October 28, 2023
DOI: https://doi.org/10.4178/epih.e2023096
  • 11,535 View
  • 274 Download
  • 4 Web of Science
  • 4 Crossref
AbstractAbstract PDF
Abstract
OBJECTIVES
The physical activity paradox suggests that occupational physical activity (OPA), unlike leisure-time physical activity (LTPA), may detrimentally impact health. We explored the relationships of OPA and LTPA with work ability (WA) and health-related productivity loss (HRPL).
METHODS
This study included 5,501 workers in Korea who were recruited in 2021 through a web-based cross-sectional questionnaire. The questionnaire was utilized to quantify OPA and LTPA in metabolic equivalents, while WA and HRPL were also measured. Non-parametric regression, using a generalized additive model (GAM), was employed to visualize the relationships of LTPA and OPA with WA and HRPL. Mean differences in WA and HRPL, in relation to OPA and LTPA, were examined using linear regression models. These models were adjusted for covariates including sex, age, body mass index, education level, alcohol consumption, smoking history, insomnia, occupation, hours worked, and income.
RESULTS
The GAM and linear regression analyses revealed that higher LTPA corresponded with higher WA and lower HRPL. In contrast, as OPA increased, WA decreased and HRPL increased. However, within the group with high OPA, HRPL was not significantly lower in the high-LTPA subgroup relative to the low-LTPA subgroup (mean difference=1.92%, p=0.343). This pattern was especially pronounced among workers aged 60 years and older, with an increase in HRPL observed with increasing LTPA among the respondents with high OPA.
CONCLUSIONS
High LTPA levels were associated with elevated WA and diminished HRPL. In contrast, higher levels of OPA were associated with lower WA and higher HRPL.
Summary

Citations

Citations to this article as recorded by  
  • Data profile: Korean Work, Sleep, and Health Study (KWSHS)
    Seong-Sik Cho, Jeehee Min, Heejoo Ko, Mo-Yeol Kang
    Ann Occup Environ Med.2025; 37: e3.     CrossRef
  • Association between work stress and sleep disturbances: the mediating role of pre-sleep arousal symptoms
    Jeehee MIN, Hoje RYU, Seong-Sik CHO, Mo-Yeol KANG
    Industrial Health.2025; 63(5): 478.     CrossRef
  • Understanding the Link Between Physical Activity and Work Ability in University Staff: Protocol for a Gender-Sensitive Cross-Sectional Study
    Laura Lorenzo-Gallego, Silvia Muñoz-Pastor, Maria Remedios Menéndez-Calvo, Beatriz Navarro-Brazález, María Torres-Lacomba
    JMIR Research Protocols.2025; 14: e80298.     CrossRef
  • Association between the safety climate and occupational injury in the Korean working population: a cross-sectional study
    Jeehee Min, Tae-Won Jang, Hye-Eun Lee, Mo-Yeol Kang, Seong-Sik Cho
    Epidemiology and Health.2024; 46: e2024082.     CrossRef
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