South Korea Research Articles

Climate temperature and seasonal influences on the prevalence of temporomandibular disorders in South Korea

This study aimed to explore seasonal variations in temporomandibular disorder (TMD) prevalence in South Korea, utilizing nationwide population-based big data. Data corresponding to the Korean Standard Classification of Diseases code of K07.6, which identifies TMD, were extracted from the Health Insurance Review and Assessment Service online platform for the period from 2010 to 2022. Additionally, we integrated these data with climate temperature records from the Korean Meteorological Administration. We subsequently conducted a statistical analysis of TMD patient data on a monthly and seasonal basis over the past 13 years to assess prevalence. Over the past 13 years, the number of TMD patients in Korea has steadily increased. The prevalence of TMD rose from 0.48% (224,708 out of a total population of 50,515,666) in 2010 to 0.94% (482,241 out of a total population of 51,439,038) in 2022, marking a 1.96-fold increase. Among children under 10 years of age, no significant differences were observed in TMD prevalence between boys and girls. However, a distinct female predominance emerged after the age of 10, with an average female-to-male ratio of 1.51:1. The peak prevalence of TMD occurred in individuals in their 20 s, followed by adolescents in their late 10 s. The majority of TMD patients were concentrated in Seoul and Gyeonggi province, with metropolitan areas accounting for 50% of the total patient count. Seasonally, TMD patient numbers showed no significant increase in winter compared with spring or summer. The temperature difference, defined as the absolute difference between the highest and lowest temperatures for each month, showed a positive correlation with TMD patient counts. A greater temperature difference was associated with higher patient counts. The strongest correlation between temperature differences and TMD patient numbers was observed in winter (r = 0.480, p < 0.01), followed by summer (r = 0.443, p < 0.01), and spring (r = 0.366, p < 0.05). Temperature differences demonstrated a significantly stronger correlation with the increase in the number of TMD patients than absolute climate temperatures. This aspect should be a key consideration when examining seasonal trends in TMD prevalence in South Korea.

Seawater intrusion effects on nitrogen cycling in the regulated Nakdong River Estuary, South Korea

Seawater intrusion effects on nitrogen cycling in the regulated Nakdong River Estuary, South Korea

The effects of organizational images on security compliance intention: focused on affection and job security in South Korea

The effects of organizational images on security compliance intention: focused on affection and job security in South Korea

Seismic anisotropies of the Yugu peridotites (Gyeonggi Massif, South Korea) and their seismic implications in mantle shear zones

Seismic anisotropies of the Yugu peridotites (Gyeonggi Massif, South Korea) and their seismic implications in mantle shear zones

Trajectories of nursing hours over the course of hospitalization and estimated additional nurse staffing requirements to reduce the length of stay.

The aims of this study are to examine the trajectories of nursing hours per patient day (NHPPD) over the course of hospitalization according to the patient's length of stay (LOS) and to estimate changes in the total nursing hours during hospitalization, average NHPPD, and the number of nurses additionally required when the LOS was reduced by 1 day. This retrospective longitudinal study analyzed patient data collected from a tertiary university hospital located in Seoul, South Korea. The study sample included 11,316 inpatients who were discharged between September 1 and October 31, 2022. NHPPD over the course of each patient's hospitalization was estimated using the total score of the Korean Patient Classification System-1 (KPCS-1), which nurses evaluated and recorded every day from admission to discharge. The NHPPD trajectories were examined using linear mixed models to analyze repeated KPCS-1 measurements and control for the effects of patient characteristics. The changes in the average NHPPD when LOS was reduced by 1 day were estimated using maximum and minimum estimations. The impact of a 1-day reduction in LOS on staffing requirements was calculated as the number of nurses additionally required to work each shift and to be hired. The average LOS was 5.6 days, and the short (1-6 days) and medium (7-14 days) LOS groups accounted for 78.9% and 14.3% of patients, respectively. The NHPPD trajectories showed a "rise-peak-decline" pattern. Patients in the short LOS group received the most NHPPD on day 1 (day of admission) or day 2, whereas the NHPPD for patients in the medium LOS group peaked on days 3-6. After peaking, the NHPPD tended to decrease toward the end of hospitalization, with the least NHPPD on the day of discharge, followed by the day before discharge. When LOS was reduced by 1 day, the average NHPPD was estimated to increase by 7.7-50.0% in the maximum estimation, and 0.9-12.5% in the minimum estimation. In response to a 1-day reduction, 1.10-7.44 nurses were additionally required to care for 100 patients each shift and 5.28-35.70 additional nurses needed to be hired in the maximum estimation. In the minimum estimation, these values were 0.13-1.85 additional nurses per shift and 0.65-8.90 additional nurses to be hired, respectively. Since NHPPD exhibited a "rise-peak-decline" trajectory, reducing the LOS by 1 day was estimated to increase the average NHPPD and lead to additional staffing requirements. The additional nurse requirement for a 1-day reduction was not constant; instead, it increased with each day subtracted from an already shorter LOS. Sufficient nurse staffing is necessary to provide increased NHPPD as a result of shortened LOS. Changes in the LOS should be considered when determining nurse staffing requirements.

Generalized trust and attitudes toward immigrants in East Asia: A cross-national comparative study

Generalized trust has been widely discussed as a non-economic determinant influencing public attitudes toward immigrants among natives in Europe. However, associations between generalized trust and public opinions on immigrants remain underexplored in East Asia. This study investigates the association between generalized trust among natives and their attitudes toward immigrants, considering the interaction between generalized trust and country. Utilizing data from the 7th wave of the World Values Survey dataset for three East Asian countries—South Korea, China, and Japan—we fitted two mixed multilevel logistic regression models for two dependent variables in two scenarios: opposition to immigrants as neighbors, and prioritizing nationals in economic adversity. Results reveal that generalized trust was negatively related to natives' reluctance to accept immigrants as neighbors. However, the association was only marginally significant when examining support for in-group favoritism in economic adversity. The impact of generalized trust on these attitudes also exhibited variations by country. Notably, we found a negative association between generalized trust and opposing immigrants as neighbors in China and Japan, while this may not be the case for Korea.

Variation in Root Biomass and Distribution Based on the Topography, Soil Properties, and Tree Influence Index: The Case of Mt. Duryun in Republic of Korea

Root biomass and distribution are influenced by abiotic factors, such as topography and soil physicochemical properties, determining belowground productivity. Hence, we investigated the variation in root biomass and vertical root distribution based on the topography, soil physicochemical properties, and tree influence index, and their relationships, across soil depths (0–10 cm, 10–20 cm, and 20–30 cm) and topographical gradients in a warm-temperate forest in Mt. Duryun, Republic of Korea. Two contrasting research sites were established: a lower slope oriented at ≤3° and an upper slope with a slope of 30°. Each site comprised eleven 400 m2 sampling plots from which root samples from various diameter classes (&lt;2 mm, 2–5 mm, 5–10 mm, and &gt;10 mm) were collected. While the bulk density increased with soil depth in the lower slope, the organic matter, available phosphorus, Ca2+, and Mg2+ showed a reversed pattern. Linear mixed-effects models generally revealed significant negative correlations between root biomass and soil pH, total nitrogen, and cation exchange capacity, particularly in small roots (βstd = −1.03 to −1.51) and coarse roots (βstd = −6.30). Root biomass exhibited a 10–15% increase in the upper slope compared to the lower slope, particularly in fine (median = 52.0 g m2–65.64 g m2) and medium roots (median = 56.04 g m2–69.52 g m2) at a 0–20 cm soil depth. While no significant correlation between root biomass and the tree influence index was found on the lower slope, a different pattern was found on the upper slope. Our results indicate that the variation in root biomass and distribution can also be explained by the differences in the soil environment and topographical positions.

Secular trends in the incidence and treatment patterns of primary hyperparathyroidism in Korea: a Nationwide cohort study

Abstract Data on epidemiology and secular trend in primary hyperparathyroidism (PHPT) in adults is relatively limited in Asian countries. This study aims to provide an overview of the secular trends in incidence, clinical characteristics, and treatment patterns of PHPT in South Korea. We used Korea’s National Health Insurance Claim database (2005–2020) to identify newly diagnosed PHPT cases. Individuals with age below 19, fewer than two E21.0 diagnoses, fewer than two parathyroid hormone measurements, secondary hyperparathyroidism, undergoing dialysis or kidney transplantation within a year of diagnosis, parathyroidectomy (PTX) within a year prior to the diagnosis code, and diagnosis of multiple endocrine neoplasm or parathyroid carcinoma were excluded from the analysis. A total of 6837 patients with PHPT (PTX, n = 2989; non-surgery, n = 3848) were compared to 1:10 age- and sex-matched controls (n = 68 370). The mean age of patients with PHPT was 56.0 years, with 77.4% being women. The annual incidence of PHPT increased from 0.23/100000 persons in 2005 to 1.75 in 2020, with higher rate in women than in men. Compared to 2005-2010 (n = 675), the number of newly diagnosed PHPT cases increased up to 3.1-fold (n = 2119) in 2011-2015 and 6.0-fold (n = 4043) in 2016-2020 periods. Among all patients with PHPT, 43.7% of patients underwent PTX, with decrement of proportion of bilateral surgery among PTX group across time (11.9% in 2005-2010 to 8.9% in 2016-2020, p for trend 0.033). Among all patients with PHPT, non-surgery group increased from 41.6% in 2005-2010 to 58.0% in 2016-2020 (p for trend &amp;lt;0.001). Patients with PHPT had higher odds of osteoporosis (odds ratio [OR] 7.03), renal stones (OR 10.55), chronic kidney diseases (OR 7.42), and cardiovascular, metabolic, and neurological conditions after adjustment for comorbidity index. In summary, the incidence of PHPT increased from 2005 to 2020 with predominance of non-surgical treatment, which calls for research focus on improving non-surgical management.

A Non-Intrusive Method for Lonely Death Prevention Using Occupancy Detection and an Anomaly Detection Model

In countries like Japan, Australia, France, Denmark, and South Korea, the numbers of single-person households and older adults living alone have been steadily increasing each year, leading to the social issue of lonely deaths among older adults. Against this backdrop, this study proposes a method to develop a system for preventing lonely deaths based on information technology, including the Internet of Things (IoT). IoT sensor data, which include nine environmental variables such as indoor temperature, relative humidity, CO2 concentration, fine dust particle levels, illuminance, total volatile organic compound levels, and occupancy data collected from passive infrared sensors, provide empirical evidence so that anomalies can be detected in the behavior patterns of older adults when they remain in one place for an unusually long time. Detecting such risky situations for older adults living alone involves anomaly detection through occupancy monitoring. The data from occupancy monitoring were analyzed using four classification models, namely Logistic Regression, k-Nearest Neighbor, Decision Tree, and Random Forest, with the performance of occupancy detection being compared across these models. Furthermore, the method proposed in this study includes data processing for environmental variables to improve the performance of occupancy detection.

Decent Work Profiles of Korean Workers: Antecedents and Outcomes of Profile Membership

Recent research has explored profiles of decent work based on the Psychology of Working Theory. However, such investigations have rarely been attempted in Korea. This study applied latent profile analysis to discover decent work profiles and their relationships with antecedents and outcomes. Among 605 Korean workers, five distinct profiles emerged: indecent (7.9%), low safety and healthcare access (34.9%), average (38.1%), decent (13.7%), and value-dominant but low rest (5.4%). Higher subjective social status and work volition were associated with the decent work group, whereas women and individuals with less education were linked to work characterized by greater vulnerability. Furthermore, satisfaction with work needs, job, and life varied significantly across these profiles. The decent work group generally exhibited the highest satisfaction, whereas the indecent work group had the lowest. The low-safety and healthcare access work group tended to exhibit higher satisfaction levels than the indecent work group, but lower levels than the average work group. The v alue-dominant but low-rest work group exhibited life satisfaction comparable to the decent work group. The findings of this study highlight the distinctive characteristics of the working conditions in South Korea. Based on these results, we discuss theoretical and practical implications.

Association between the transition to metabolically unhealthy obesity and lifestyle behavior: A nationwide cohort study.

To identify the characteristics of individuals transitioning from metabolically healthy obesity (MHO) to unhealthy obesity and the factors influencing the change. This is a nationwide cohort study using data from the National Health Insurance Service in South Korea. Individuals with obesity but metabolically healthy in 2009 and 2010 and those still obese 4 years later were selected. Sociodemographic, physical, metabolic, and health behavior variables were collected, and logistic regression was used to find an association with the transition. We analyzed 1,564,467 individuals, observing significant differences in all variables and the transition from MHO to unhealthy obesity. Among males, the transition was associated with smoking and drinking positively and physical activity negatively. Among females, drinking demonstrated a negative correlation. Regardless of age, regular exercise was negatively associated with the transition for all individuals. Except for older adults, all age groups showed a positive correlation with smoking and drinking. Considering the significant factors in the transition, it is essential to develop and implement interventions varied by gender and age to delay and prevent the change in metabolic status. The necessity of developing interventions enables individuals to engage in regular exercise, regardless of age and gender.

Residential mobility according to health status in South Korea's largest metropolitan city during the COVID-19 pandemic using generalized estimating equations for longitudinal data

This study examines whether residential mobility differed according to health status in Seoul, the largest metropolitan city in South Korea, during the COVID-19 pandemic. Before the COVID-19 pandemic, people who moved had better health status in the baseline year than those who did not. However, during the pandemic, the residential mobility of people with poor health status increased, particularly in 2019–2020. This pattern appeared to be driven by the 55–74 age group. The effect of health status on residential mobility was not attenuated, even after adjusting for covariates at multiple levels.

Tax Revenue In Asian Countries: Contribution Of Economic Sector With The Rule Of Law As A Moderating Variable

The implementation of government effectiveness aims to provide the best service to the community. The effectiveness of this organization can be measured by one of them using The Worldwide Governance Indicators (WGI) project index. From 2010 to 2019, there are seven Asian countries with effectiveness indexes above the world average, namely Georgia, Hong Kong, Thailand, Japan, South Korea, Singapore, and Malaysia. Through this study, it will be assessed whether this effectiveness supports tax revenue by conducting research on the effect of the contribution of the industrial sector and the service sector to Gross Domestic Product (GDP) on the effect of tax revenue. Then the author also conducts research whether the interaction of moderating variables, in this case the Rule of Law Index variable with the two independent variables (the contribution of the industrial sector and the service sector to Gross Domestic Product (GDP)) has an influence on the contribution of tax revenue to GDP considering that law enforcement is one of the steps in the implementation of controlling tax payments. The results obtained in this study state that before the interaction with moderating variables, the independent variables, namely the industrial sector and the service sector in GDP contribution, have a significant negative effect on tax revenue. Then when the moderating variable, namely the rule of law index, interacts with the industrial sector and the service sector, the effect of the two independent variables on the tax revenue variable has increased to a significant positive effect, so that the moderating variable in this study has a role that strengthens the influence of the independent variable on the dependent variable.

Population genomics of the invasive Northern Giant Hornet Vespa mandarinia in North America and across its native range

The northern giant hornet Vespa mandarinia (NGH) is a voracious predator of other insect species, including honey bees. NGH’s native range spans subtropical and temperate regions across much of east and southeast Asia and, in 2019, exotic populations of the species were discovered in North America. Despite this broad range and invasive potential, investigation of the population genomic structure of NGH across its native and introduced ranges has thus far been limited to a small number of mitochondrial samples. Here, we present analyses of genomic data from NGH individuals collected across the species’ native range and from exotic individuals collected in North America. We provide the first survey of whole-genome population variation for any hornet species, covering this species’ native and invasive ranges, and in doing so confirm likely origins in Japan and South Korea for the two introductions. We additionally show that, while this introduced population exhibited strongly elevated levels of inbreeding, these signatures of inbreeding are also present in some long-standing native populations, which may indicate that inbreeding depression alone is insufficient to prevent the persistence of NGH populations. As well as highlighting the importance of ongoing monitoring and eradication efforts to limit the spread of this species outside of its natural range, our data will serve as a foundational database for future genomic studies into introduced hornet populations.

Thyroid Cancer Incidence Among Korean Individuals: A Comparison of South Korea and the United States.

To compare thyroid cancer incidence rates and trends between Korean, non-Korean Asian, and non-Hispanic White populations in the United States, and between the US Korean population and the South Korean population. Population-based analysis of cancer incidence data. Cases of thyroid cancer diagnosed during 1999-2014 from the Korean Central Cancer Registry (KCCR) and the Surveillance, Epidemiology, and End Results (SEER) 9 detailed Asian/Pacific Islander subgroup incidence and population dataset were included. Incidence rates were obtained from the datasets, and annual percent change (APC) of the incidence rates was calculated using Joinpoint regression analysis. Thyroid cancer incidence rate for 1999-2014 was significantly higher for South Korea (48.05 [95% CI 47.89-48.22] per 100,000 person-years) than for the US Korean population (11.12 [95% CI 10.49-11.78] per 100,000 person-years), which was slightly higher than the Non-Korean Asian population (10.23 [95% CI 10.02-10.43] per 100,000 person-years), and slightly lower than the Non-Hispanic White population (12.78 [95% CI 12.69-12.87] per 100,000 person-years). Incidence rates in South Korea increased dramatically (average APC 17.9, 95% CI 16.0-19.9), significantly higher than the US Korean population (average APC 5.0, 95% CI 3.1-6.8), which was similar to the non-Korean Asian (average APC 2.5, 95% CI 0.9-4.2) and the non-Hispanic White (average APC 5.1, 95% CI 4.7-5.6) populations. South Korea's high thyroid cancer incidence rates cannot be attributed to genetic factors, but are likely due to health care system factors. 3 Laryngoscope, 2024.

Impact of national health insurance and socioeconomic disparities on newborn hearing screening performance in South Korea: A nationwide population-based evaluation

ObjectivesThis study aimed to assess the impact of national health insurance coverage on newborn hearing screening (NHS) outcomes by analyzing hearing questionnaires from the National Infant Health Check-up Program (NIHCP) in South Korea. MethodsThis study evaluated the performance and referral rates of NHS using nationwide data from 814,875 infants enrolled in the 4-month NIHCP from January 2017 to December 2019. This period encompasses the periods before and after the National Health Insurance in South Korea began covering NHS expenses in October 2018. The study also investigated household income levels to determine their relationship with participation in the NIHCP and NHS outcomes. ResultsThe performance of NIHCP increased year-on-year, with NHS performance rates increasing from 88.5 % in 2017 to 91.5 % in 2019. Analysis by household income level revealed that the medical benefit recipients’ group had the lowest NHS performance rate of 81.9 % in 2019, whereas that of the higher income level group exceeded 90 %. The NHS referral rate remained consistent at 0.9 % nationally during the study period. ConclusionThe inclusion of NHS in national insurance coverage positively influenced its performance rates across South Korea. Nevertheless, the data indicate the need for more focused and customized support for low-income families to enhance early hearing detection and interventions in newborns and infants.

Risk compensation after COVID-19 vaccination: Evidence from vaccine rollout by exact birth date in South Korea.

We utilize the phased rollout of COVID-19 vaccines by exact birth date in South Korea as a natural experiment for testing risk compensation. People may resume face-to-face social activities following vaccination because they perceive lower risk of infection. Applying a regression discontinuity design based on birth date cutoffs for vaccine eligibility, we find no evidence of risk-compensating behaviors, as measured by large, high-frequency data from credit card and airline companies as well as survey data. We find some evidence of self-selection into vaccine take-up based on perception toward vaccine effectiveness and side effects, but the treatment effects do not differ between compliers and never-takers.

Where’s the beef?: the politics of health care reform in South Korea

Background: In February 2024, the South Korean government released a policy proposal for healthcare reform, with one of the main pillars being increased medical school admissions. This policy has sparked intense opposition from the physicians’ top association. Most importantly, interns and residents—the bedrock of the medical workforce in Korean hospitals—began to leave en masse. Consequently, a medical crisis emerged, in which many medical and surgical procedures were delayed.Current Concepts: According to studies on comparative health policy and systems, the crisis could be attributed to the unique characteristics of the Korean healthcare system, in which the administration and doctors have failed to establish a substantive dialogue through which policy options are examined and deliberated. These dynamics necessitated the establishment of an institutional space for interest group politics, causing both to suffer from a lack of action repertoires. The stalemate we witness reflects the enduring patterns of the same issue.Discussion and Conclusion: To ensure the success of the current initiative, institutional arrangements must be established in which policymakers and physicians make a credible commitment to each other. Alternatives, for instance, include reactivating and regularizing the Health and Medical Services Policy Deliberation Committee, which could pave the way for establishing a venue where key stakeholders can discuss future agendas, such as how to ensure improved accessibility to “essential” care and mitigate its subnational variation, thereby creating a long-term vision for new health system governance in South Korea.

The incidence and risk factors of retinopathy of prematurity in South Korea: A nationwide cohort study.

Retinopathy of prematurity (ROP) is a major treatable cause of childhood blindness. Thus, epidemiological investigations are necessary for detecting and preventing ROP. Determining risk factors for ROP are also essential to improve screening methods. Therefore, we aimed to investigate the incidence and risk factors of ROP in Korea. The National Health Insurance Service (NHIS) covers almost all Koreans. Furthermore, the National Health Screening Program for Infants and Children (NHSPIC) is a government-run, health-screening program for children aged < 6 years. We used the NHIS-Infants and Children's Health Screening cohort database to evaluate the incidence of preterm infants and ROP. The database contains data on 84,005 participants, drawn from 5% of the NHSPIC survey on participants born annually during 2008 to 2012. Sociodemographic factors and systemic diseases were assessed as potential risk factors for ROP. We identified 2615 premature infants (3.11%); 846 of them had ROP (cumulative incidence: 32.4%). Although preterm births increased annually in 2008 to 2012, the ROP incidence in preterm infants did not increase by the birth year. Twenty patients (2.4%) with ROP underwent laser photocoagulation or surgery. Extremely low birth weight was a high risk factor (odds ratio [OR] = 49.86, P < .001). Moreover, chorioamnionitis (OR = 2.77, P = .028), respiratory distress syndrome (OR = 4.09, P < .001), apnea (OR = 1.59, P = .008), anemia (OR = 2.41, P < .001), and intraventricular hemorrhage (OR = 2.34, P < .001) were found to be risk factors for ROP. In conclusion, the incidence of premature babies increased between 2008 and 2012. However, the overall incidence of ROP among premature infants remained unchanged by birth year. Our findings revealed the roles of birth weight, respiratory conditions, anemia, and intraventricular hemorrhage in ROP.

Bibliometric Analysis of Nanostructured Anodes for Electro-Oxidative Wastewater Treatment

Last decade, a growing emphasis on developing sustainable and environmentally friendly technologies for electro-oxidative wastewater treatment has catalyzed innovation and spurred research efforts worldwide. Researchers may explore the use of renewable energy sources to drive electrochemical processes, as well as the development of eco-friendly electrode materials for wastewater treatments. The integration of nanostructured anodes into the electrolytic system for wastewater treatment has led to significant advancements in the removal of pollutants via electro-oxidation. Despite the great number of research articles related to the development and use of nanostructured anodes for electro-oxidative wastewater treatment, to our knowledge, no bibliometric analysis has been published in this domain. Therefore, this work presents a bibliometric study of publications on the designated theme, retrieved from the Web of Science Core Collection database, which were published over the last decade. The visual and network analysis of co-authorship among authors, organizations, countries, co-citation of authors, citation of documents and sources, as well as the co-occurrence of author keywords was performed using two compatible pieces of scientometric software, namely VOSviewer (version 1.6.18) and CiteSpace (version 6.2.R4). From 2013 to 2023, there has been a gradual increase in the number of publications regarding the development and use of nanostructured anodes for electro-oxidative wastewater treatment. It suggests a steady advancement in this field. The People’s Republic of China emerges as the most productive country, and it is a leader in international collaborations. Also, the United States of America, South Korea, and European Union countries have significant impacts on the research in this domain. The development and application of nanostructured materials for urea electro-oxidation is a main and prospective research theme. This bibliometric analysis allowed for the visualization of the present landscape and upcoming trends in this research field, thereby facilitating future collaborative research endeavors and knowledge exchange.