• Communications for Statistical Applications and Methods
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• v.17 no.3
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• pp.337-347
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• 2010

Most sample surveys are designed to estimate reliable statistics for the whole population and for some large subpopulations. However, the research for small area estimation have been increasing in recent years because users demand to reliable estimates for smaller subpopulations like small areas or specific domains. In Korea, the Economically Active Population Survey(EAPS) is the main household survey that produces monthly unemployment rates for nationwide and 16 large areas (7 metropolitans and 9 provinces) in Korea. For county level estimation, direct estimators are not reliable because of the small sample sizes. We consider small area estimation of the county level unemployment ratesfrom the sample observations in EAPS. To do this, we use an area level model to "borrow strength" from the auxiliary information, such as administrative data and census data. The proposed method is based on the assumption of normality of the model errors in the area level model. The proposed method is compared with the other alternatives in terms of the estimated mean squared errors.

• Journal of Preventive Medicine and Public Health
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• v.39 no.4
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• pp.325-330
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• 2006

Objectives: The aims of this study were to examine the level of airborne fungi and environmental factors in Seoul metropolitan subway stations and to provide fundamental data to protect the health of subway workers and passengers. Methods: The field survey was performed from November in 2004 to February in 2005. A total 22 subway stations located at Seoul subway lines 1-4 were randomly selected. The measurement points were subway workers' activity areas (station office, bedroom, ticket office and driver's seat) and the passengers' activity areas (station precincts, inside train and platform). Air sampling for collecting airborne fungi was carried out using a one-stage cascade impactor. The PM and CO2 were measured using an electronic direct recorder and detecting tube, respectively. Results: In the activity areas of the subway workers and passengers, the mean concentrations of airborne fungi were relatively higher in the workers' bedroom and station precinct whereas the concentration of particulate matter, $PM_{10}\;and\;PM_{2.5}$, were relatively higher in the platform, inside the train and driver's seat than in the other activity areas. There was no significant difference in the concentration of airborne fungi between the underground and ground activity areas of the subway. The mean $PM_{10}\;and\;PM_{2.5}$ concentration in the platform located at underground was significantly higher than that of the ground (p<0.05). Conclusions: The levels of airborne fungi in the Seoul subway line 1-4 were not serious enough to cause respiratory disease in subway workers and passengers. This indicates that there is little correlation between airborne fungi and particulate matter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4968-4979
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• 2011

The purpose of this study was to investigate the effects of Socioeconomic factors on medical information resources when medical consumer choose inpatient or outpatient services. The target population was 12,249 people aged above 19 in Chungcheongbuk-do. The sample was accrued for the period of 3 months in 2008 by face to face interview of direct visiting from systematic sampling method. There was a significant difference in the use of personal informer and public informer by sex(p<0.001). There was a significant difference in the use of experimental and professional informer by living area(p<0.001). In conclusion, the results suggest that there is relationship between medical information resource and socioeconomic factors of medical consumer.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1048-1057
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• 2017

An indirect matrix converter (IMC) is a modern power generation system that enables a direct ac/ac conversion without the need for any bulky and limited lifetime electrolytic capacitor. This system also allows four-quadrant operation, generation of sinusoidal output voltage waveforms with variable frequency and amplitude, and control of input power factor. This study proposes a pulse-width modulation-based sliding-mode controller to achieve unity input-power factor operation of the IMC independently of the active power exchanged with the grid, as well as a fast dynamic response. The designed equivalent control law determines, at each sampling period, the appropriate q-axis component of the modulated input current to be injected into the grid through the LC input filter. An integral term of the error is included in the expression of the sliding surface to increase the accuracy of the control method. A double space vector modulation method is used to synthesize the direction of the space vector of the input currents as required by the sliding-mode controller and the space vectors of the target output voltages. Simulation and experimental results are provided to show the effectiveness and evaluate the performance of the proposed control method.

• Journal of Environmental Health Sciences
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• v.45 no.5
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• pp.405-425
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• 2019

Objective: This study aimed to review the methodologies for evaluation of consumer spray products containing engineered nanomaterials (ENM), particularly focusing on inhalation exposure. Method: Literature on the evaluation methods for aerosolized ENM exposure from consumer spray products were collected through academic web searching. Common methodologies used in the literature, including research reports and academic articles, were also introduced. Results: The number of ENM-containing products have shown a considerable increase over recent years, from 54 in 2005 to 1,827 in 2018. Currently there is still discussion over the existing regulations with regard to product safety. Analysis of both ENM suspensions in the products and their aerosols is important for risk assessment. Comparison between the phases suggests how the size and concentration of particles change during the spray process. To analyze the ENM suspensions, dynamic light scattering, electron microscopy techniques, and inductively coupled plasma with mass spectrometry were used. In the aerosol monitoring, direct-reading instruments have been used to monitor the aerosols and conventional active sampling is used together to supplement the lack of real-time monitoring. There are also some models for estimating inhalation exposure. These models may be used to estimate mass exposure to nanomaterials contained in consumer products. Conclusion: Although there is no standardized method to evaluate ENM exposure from consumer products, many concerns about ENM have emerged. Every potential measure to reduce exposure to ENM from spray product use should be implemented through a precautionary recognition.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.435-451
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• 2021

The purpose of the study is to explore the experience of participants who have provided a chidlcare service, and to suggest implications for childcare service for adolescent parents. The author used a purposive sampling method to select 3 cases with experiences related to childcare service, collecting data via direct interview and by obtaining a written text describing their case management. An inductive (open) coding approach was utilized to draw themes and categories from the data. The 6 categories describing service providing experiences of the study participants include "motives for participate a childcare service", "contents of service provided by participants", "tries to establish relationship with adolescent parents", "deepening of understand about adolescent parents", "limits of providing services". Implications and future directions were discussed for childcare services on adolescent parents having crisis related to childbirth and child rearing.

• Journal of the Korea Convergence Society
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• v.9 no.12
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• pp.345-354
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• 2018

The purpose of this study was to investigate the structural relationship between advertising attributes, advertising attitude, brand image, and purchase intention of sports brand on SNS. For this purpose, 250 valid samples from the convenience sampling method were used as the final analysis data. Entertainment, information, and credibility among ad attributes had a positive effect on SNS users' advertisement attitude toward sport brands, and irritation has a negative effect on ad attitude. The ad attitude formed by the advertising attributes positively affected the image of the sports brand and the purchase intention. Brand image had a positive effect on purchase intention. The results of this study may be helpful to maximize SNS advertising effect of sports brands and to identify some important factors that can affect direct purchasing behavior of sports majors, one of the target groups of companies promoting sports brands using SNS.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.74-85
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• 2021

Global Navigation Satellite System (GNSS) receivers are intrinsically vulnerable to radio frequency jamming signals due to the fundamental property of radio navigation systems. A GNSS jamming monitoring system that is capable of jamming detection, classification and localization is essential for infrastructure for autonomous driving systems. For these 3 functionalities, a GNSS jamming monitoring network consisting of a multiple of low-cost GNSS receivers distributed in a certain area is needed, and the precise time synchronizaion between multiple independent GNSS receivers in the network is an essential element. This paper presents a precise time synchronization method based on the direct use of Time Difference of Arrival (TDOA) technique in signal domain. A block interpolation method is additionally incorporated into the method in order to maintain the precision of time synchronization even with the relatively low sampling rate of the received signals for computational efficiency. The feasibility of the proposed approach is verified in the numerical simualtions.

• Journal of Korean society of Dental Hygiene
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• v.21 no.4
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• pp.413-425
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• 2021

Objectives: This study aimed to provide basic data to lay the groundwork for the introduction of an advanced dental hygienist system by sampling dental hygienists' views about the system. Methods: A nationwide questionnaire survey was conducted targeting 857 dental hygienists working at dental hospitals and clinics, local health institutions, and educational institutions. The collected data were analyzed using frequency analysis, t-test, one-way analysis of variance (ANOVA) (Duncan as post-analysis), and crossover analysis. Results: The average interest level in the advanced dental hygienist system was 3.83±0.95 points. The necessity by field was confirmed to be the highest during dental hygiene for the elderly and persons with disabilities. The working experience necessary for becoming a specialized dental hygienist is 5.56±2.99 (years). The education period necessary for becoming a specialized dental hygienist is 77.30±77.61 (hours). The work authority level for an advanced dental hygienist was indicated to be 50 respondents (5.8%), who said they required direct guidance from a dentist, 313 respondents (48.2%) who said they needed indirect guidance from a dentist, 200 respondents (23.3%) who said OK when given an advanced dental hygienist's separate judgment, 194 respondents (22.6%), who said that the authority must be varied depending on the work. Conclusions: The interest and need of the advanced dental hygienist system were proven to be high and are expected to be applied to basic data for the introduction and settlement of the system.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.553-563
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• 2021

Customer value has long been believed to be a direct trigger for increased tourist satisfaction, but as a mediating variable, it still needs to be proven further. This paper aims to examine the causal relationship between research variables, as well as to examine the role of customer value as a mediating variable in the relationship between service quality, brand quality, tourism products, customer value, and tourist satisfaction with tourists' objects. The population is tourists who visit tourist sites/destinations in the Gianyar Regency on the island of Bali, Indonesia, and the sample size is 270 respondents, selected through random sampling. Structural equation modeling (SEM), a multivariate statistical analysis technique, is used to analyze the causal relationships between variables. The results show that the model is accepted, and customer value is proven to be a positive mediating variable. The results also show that service quality, brand quality, and tourism products have an effect on customer value. This provides insight into the practical implications for tourism managers to increase the brand quality of tourist attractions as well as increase the professionalism and quality of tour guide services. This, in turn, will increase customer value and increase tourist satisfaction.