• Korea journal of population studies
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• v.24 no.1
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• pp.41-65
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• 2001

This study aims a comparative analysis of social stratification in the Great Seoul area using two types of population. One type of population is a resident population(常住人口), and the other is a daytime population주간인구(晝間人口). In most demographic studies, only resident population have been considered. There has been less attention to daytime population. However, a resident population have a character of night population야간인구(夜間人口). In fact, most people move and work in the areas where they do not live in everyday life in the contemporary period, which indicates that the concept of a daytime population is more significant than that of a resident population. This study reveals that a number of people, on the one hand. come together to the downtown area to work or study while they live in other areas. On the other hand, resident population in downtown area do not move so much. When we analyze the social stratification structure of the Great Seoul area using a resident population, we find that the resident population of downtown area consist of those of low social status. On the contrary, the daytime population of downtown area in Seoul consist of those of high social status. This means that most people of high social status live in the southern area of Seoul or outside Seoul, but make a living in downtown area in everyday life. From this study, we find that the concept of a daytime population is as important as that of a resident population. The more residence becomes separate from work place, the more the significance of the concept of a daytime population grows in making policy as wall as in demographic studies. This study implies that we need to pay more attention to the concept of daytime population in demographic and sociological Studies.

• Survey Research
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• v.12 no.2
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• pp.27-50
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• 2011

It is increasingly important to estimate daytime population for the sake of urban administration and urban economy. The estimation of daytime population using a census data on commute, however, has its own limits, particularly when applying to the metropolis such as Seoul which is dominated by the service industry. This study suggests a pedestrian flow as another estimate of daytime population and presents a methodology of Seoul Pedestrian Flow Survey. The data of pedestrian flow gives us a view into hourly and spatial distribution of daytime population, which cannot be provided by the use of census data. In addition, comparing with a census-based daytime population on the borough level show some features of a pedestrian flow as another estimate of daytime population.

• Korea Journal of Hospital Management
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• v.18 no.2
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• pp.15-32
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• 2013

Few public health researchers have paid research attention to the location of medical institutions in Korea. Previous studies were published in geography journals, and relied on limited data in terms of geographic regions and the type of medical institutions. This study utilized nationwide data covering 8 types of medical institutions. We obtained data from Health Insurance Review and Assessment Service and National Population and Housing Census. The correlation coefficients of resident, daytime, university-graduate population, and the population of different age groups (fewer than 15, 15~64, 65 or more) were compared to understand their relative association with the location of medical institutions. Medical clinic, dental clinic, oriental medical clinic, and pharmacy, all of which are almost completely operated by private sector, showed strong positive correlation with population. Hospital-level medical institutions, which are operated by both public and private sector, had moderate positive correlation. Daytime population and university-graduate population, rather than resident population, were more correlated with the location of medical clinics. The correlation coefficients of the population of 15~64 age group and the location of medical institutions were greater than that of other age groups. The results showed that daytime and university-graduate population are more important than resident population to explain the location of medicalrelated facilities. The results also suggests that the population of age groups (especially, 15~64) might be one of important influence factors in the location of medical institutions.

• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.222-233
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• 2016

Recently, mobile phone data was applied in travel demand modeling as a new source of dynamic population movement. This study is also aimed to estimate "occupancy population" during a given period of time within a given spatial region using mobile phone data. An occupancy population was defined as the number of people residing or moving within a given time and space. In case of Seoul Metropolitan area, we divided the area into a number of administrative districts as zones for analysis and estimated the occupancy population of each zone by mobile phone data collected by SK telecom Co., a wireless telecommunication provider in Korea. For the expansion of mobile phone data, a new concept of "communication probability" was introduced and applied in the estimation of occupancy population of each zone by the hour. We compared the estimated number with the daytime population and the daytime population index referred by the Statistics Korea. The results showed that a positive correlation existed between the estimated number and the statistical number by nationwide survey. It was concluded that mobile phone data could be more cost-effective sources than a conventional survey method to estimate the pattern of population movement by the hour or by the day.

• Journal of Environmental Health Sciences
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• v.41 no.2
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• pp.71-81
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• 2015

Objectives: Photochemical ozone pollution is associated with increased mortality risk. This study aims to assess the population exposure to ozone according to population characteristics for high ozone days in the Busan metropolitan region (BMR). Methods: The ozone exposure assessment in this study was performed using the WRF-CMAQ simulated ozone concentrations and the population data in the BMR. The settled and daytime population and their activity were considered to conduct the static and dynamic ozone exposure assessment. Results: Applying a static exposure assessment, in case that high ozone occurred throughout Busan area, the highest exposure levels were evaluated in urban neighborhoods. In case of ozone pollution in outer Busan, because sensitive groups have been relatively higher exposure, this case was also evaluated as part of that should not be overlooked. The dynamic exposure was higher than static exposure because the number of population exposed to ozone of high concentration is increased. This approach is important in a regard consider that daytime population distribution when high ozone occur. Conclusion: This study shows the different population exposure according to various ozone distributions for each episode day. Considering demographic characteristic such as population density and activity should be important to understanding the population exposure assessment when ozone pollution occurs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.1-10
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• 2016

Seoul, a mega city, contains many features of the modern city. When the disaster or emergency occurs in Seoul, the place for shelter is required for evacuation urgently. There are currently the numbers of shelters in Seoul City, which can hold the twice more capacity of population of Seoul. However, the population distribution fluctuation in the day and the night needs to be considered. Therefore, in order to analyze the actual capacity of shelter, it is necessary to consider the dynamic characteristics of population distribution in the metropolitan area. In the study, the substantial accessibility and the capacity of shelters in Seoul were analyzed by the floating population data of the metropolitan area. The accessibility of shelter was investigated through a network analysis that includes the pedestrian road data, while the capacity of shelter was analyzed by the local differences of daytime population distributions. Finally it was possible to identify the vulnerable areas on the basis of the distribution of shelter in the region.

• Journal of the korean society of oceanography
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• v.33 no.1-2
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• pp.35-40
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• 1998

In February and April 1997, three temporary interruptions of electric power production at the Uljin Nuclear Power Plant in the east coast of Korea were caused by the malfunction of the cool-ing-water supply unit. The clogging of the drum screens inside the unit caused by the surface swarm of the euphausiid Euphausia pacifica Hansen might be responsible for the malfunction. These incidents were of particular interest since such interruption of reactors' operation by krill swarms had not previously been reported. Using samples caught by the drum screens inside the cooling water-supply unit, we investigated the population structure of surface swarms. One occasion of nighttime and three occasions of daytime surface swarms were found in February and April 1997, respectively. The foreguts of more than 60% of E. pacifica in nighttime surface swarm were in full condition. This evidence suggests that E. pacifica aggregates to the surface water at night for feeding. In daytime surface swarms consisting of mature E. pacifica, however, foreguts in full condition were only found in less than 10eio of krill examined, suggesting that daytime surface swarms are closely related to breeding activity. During the study period, the growth rate of mature females was more than twice higher than that of mature males. Analyses of the sex-ratio and length-frequency data show a decrease in the portion of males with increasing size. There was a decline in the number of males of 19 mm in length. Energy loss during spermatophore transfer may result in the death of male E. pacifica, as found in male E. superba.

• Safety and Health at Work
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• v.9 no.4
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• pp.462-467
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• 2018

Background: This study was conducted to investigate the effects of work on medical expenditures by the elderly. Methods: Data pertaining to individuals aged 65 or older collected by the Korean Health Panel 2008-2013 were used. The effects of work on medical expenditures were analyzed in a panel tobit model adjusted for several variables of demographic factors, socioeconomic factors, and health factors for health care. Data were also analyzed based on age groups (65-74, $75{\leq}$), type of work (waged or self-employed), and working time (daytime work or night time work). Results: Among the elderly older than 65 years, 34-37% were workers. Work among the elderly reduced medical expenditures relative to nonworking elderly. Specifically, medical expenditures were lower in individuals older than 75 years, as well as among those who were self-employed insured and had medical aid insurance and those who exercised. However, medical expenditures were higher among females, married individuals, those with a higher household income, and those with a chronic disease. Elderly wageworkers showed reduced medical expenditures than nonworking elderly and elderly daytime workers did. Conclusion: The elderly population's work, especially wage work and daytime work, reduced medical expenditures relative to no work. These results provide valuable information for policymakers by indicating that work was associated with lower medical expenditures than no work. If elderly work is to be encouraged, it is necessary to provide a variety of high-quality wage work.

• Sleep Medicine and Psychophysiology
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• v.10 no.2
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• pp.93-99
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• 2003

Objectives：Sleep loss and excessive daytime sleepiness may have serious consequences, including traffic and industrial accidents, decreased productivity, learning disabilities and interpersonal problems. Yet despite these adverse effects, there are few epidemiological studies on sleep loss and daytime sleepiness in the general population of Korea. This study investigates the number of people who suffer from sleep insufficiency, how much recovery sleep occurs on weekends, and the relationship between the amount of recovery sleep and daytime sleepiness. Methods：A total 164 volunteers, aged 20 and over, were recruited by advertisement. The subjects were workers and college students living in Seoul, Korea. Subjects were excluded if they were aged over 60；if they had medical, neurological, psychiatric or sleep disorders that could cause insomnia or daytime sleepiness；if they were not following a regular sleep schedule；if they traveled abroad during the study；or if they did not leave home to work or were shift workers. They were interviewed and given a sleep log to complete on each of 14 consecutive mornings. They also completed the Epworth Sleepiness Scale (ESS) at noontime on the last day of the second week. All statistical data were analyzed by t-test, $X^2$-test or ANOVA, using SPSS/PC+. Results：The results showed that the subjects woke up at 6：50 (${\pm}1$：16) on weekdays, 7：09 (${\pm}1$：29) on Saturdays, and 8：12 (${\pm}1$：39) on Sundays and holidays. They took more frequent and longer naps on Sundays than on weekdays and Saturdays. The mean sleep duration was 6h 35 min. on week nights, with a mean increase of about 1h on weekends. Only 9.1% of the subjects spent more than 8h in bed on week nights, with 67% spending less than 7h, and 49.4% reported recovery sleep of more than 1h on Sundays. The subjects who reported recovery sleep of more than 2h on Sundays, showed significantly more excessive daytime sleepiness than those who reported less than 30 min (F=2.62, p<.05). Conclusions：These findings suggest that sleep insufficiency and excessive daytime sleepiness are relatively common in Korea, and that the people who get insufficient sleep on weekdays try to compensate for sleep loss with oversleeping and daytime napping on Sundays and holidays. It appeared that daily sleep insufficiency had a cumulative effect and increased daytime sleepiness.

• Sleep Medicine and Psychophysiology
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• v.8 no.1
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• pp.11-17
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• 2001

In 2000, the number of people aged 65 and over increased to 3.37 million, accounting for 7.1% of the total population of South Korea. The elderly population will increase up to 19.3% in 2030. Sleep disordered breathing (SDB) seems to increase with age. More than 50-60% of old people complain of SDB-related signs and symptoms including awakening headache, excessive daytime sleepiness, fatigue, cognitive dysfunction, memory loss, personality changes, and depression. The influence of a mild degree of SDB upon the elderly is unclear, but moderate to severe SDB is well known to be associated with many diseases including hypertension, arrhythmia, myocardial infarction, stroke, dementia, and sudden death. Therefore, physicians should pay attention to elderly patients who complain of SDB related symptoms and signs that may not be normal signs of aging. Physicians need to become more sensitive to treat SDB in the elderly.