• The Korean Journal of Applied Statistics
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• v.16 no.2
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• pp.407-426
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• 2003

We consider the missing covariates problem in generalized estimating equations(GEE) model. If the covariate is partially missing, GEE can not be calculated. In this paper, we study the performance of 7 imputation methods to handle missing covariates in GEE models, and the properties of GEE estimators are investigated after missing covariates are imputed for ordinal data of repeated measurements. The 7 imputation methods include i) Naive Deletion ii) Sample Average Imputation iii) Row Average Imputation iv) Cross-wave Regression Imputation v) Carry-over Imputation vi) Bayesian Bootstrap vii) Approximate Bayesian Bootstrap. A Monte-Carlo simulation is used to compare the performance of these methods. For the missing mechanism generating the missing data, we assume ignorable nonresponse. Furthermore, we generate missing covariates with or without considering wave nonresp onse patterns.

• Journal of dental hygiene science
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• v.22 no.3
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• pp.171-179
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• 2022

Background: In this study, we investigated the changes and factors that affect daily health behaviors due to COVID-19 among adolescents. We intend to provide basic data so that a systematic and comprehensive health education program that includes physical and oral health can be made. Methods: This study was a secondary data analysis of the from the 2019 and 2020 Korea Youth Risk Behavior Web-based Survey. A final sample of 112,251 participants was anlayzed using chi-square test, and ordinal logistic regression. Results: In the case of tooth brushing, the frequency of 'never' increased in most general characteristics compared to before COVID-19. In the case of handwashing, it was found that handwashing behavior increased (increased) after COVID-19 compared to before COVID-19. As a result of confirming the factors affecting tooth brushing behavior before and after COVID-19, it was found that girls brushed teeth 2.2 times more regularly after lunch than boys. As a result of adjusting all other factors, regular tooth brushing behavior after COVID-19 was reduced by 0.79 times compared to before COVID-19. Conclusion: It is judged that it is necessary to operate a comprehensive health management program in the school so that the most basic tooth brushing for oral health and handwashing for health can become a habit. In addition, by confirming the impact of the COVID-19 pandemic on handwashing and tooth brushing behavior through this study, it is expected to be used in the development of policy data such as raising awareness of brushing and improving behaviors applicable in the current and upcoming new pandemic situations.

• Journal of Korean Academy of Nursing
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• v.38 no.2
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• pp.332-343
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• 2008

Purpose: This study was done to investigate the practice level of 14 health behaviors between male (N=139) and female (N=175) elderly and to identify the barriers to each health behavior of elderly people in Korea. Methods: Data were collected from 314 elderly people (65yr and older) living in metropolitan, urban, and rural areas. Descriptive statistics, $x^2$-test and ordinal logistic regression were used in data analysis using the SPSS Win 15 version. Results: 1) The performances were different in some health behaviors between male and female elderly people. Male elderly showed better performances in balanced diet, regular exercise, and more than 30 min of exercise, while female elderly showed better performances in restriction of fat and cholesterol, restriction on alcohol, and smoking. There were no differences in stress management and health prevention behaviors between the two groups. 2) The common significant barriers in health behaviors of the elderly in Korea were the lack of habit and physical discomfort. However, the lack of perceived benefit was a significant barrier in male elderly. Lack of time and lack of family support were significant barriers in female elderly people in Korea. Conclusion: These results suggest that tailored strategies should be developed considering the gender difference to reduce the main barriers of each health behavior in order to improve the health status of elderly people.

• The Korean Journal of Food And Nutrition
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• v.29 no.1
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• pp.115-127
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• 2016

In this study, we compared diet related attributes such as food taste preference, food consumption frequency and nutrition intake between elderly residents in their 80's of areas in Jeollanam-do that are well known for longevity and those of a part of Seoul. Structured in-depth interviews were conducted by trained interviewers on 125 consented subjects (67 Jeonnam and 58 Seoul). Differences of groups were tested using Chi-square tests for nominal or ordinal data and t-tests and ANOVA tests for ratio data. The elderly from Jeonnam tended to sleep longer, express emotion more freely, and interact with others more often than those from Seoul. The elderly tended to prefer sweet or salty tastes, which might be highly related to serious health problems. The most frequently consumed foods were napa cabbage kimchi (2.19 times/day) and multigrain rice (1.99 times/day). Elderly from Jeonnam tended to consume garlic, milk, beans and roasted barley/corn teas less often; whereas, they consumed porridge, dried radish greens, potato, fermented fish, dried fish, pork rib, pork belly, soybean paste soup, soybean paste/Ssamjang, other kimchis, pickled vegetables, snacks, cookies, and green/black teas more often than elderly residents from Seoul. Differences in nutrition intake between the regions were greater than differences between the perceived levels of household economic status. NAR and INQ for folate were lower among elderly from Jeonnam than those from Seoul, while those for protein, vitamin C, niacin, vitamin $B_6$ were higher. The study results indicated that elderly from Jeonnam engaged in a more diverse diet than the elderly from Seoul.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.93-105
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• 2006

The construction of golf courses has had adverse effects on the natural landscape and delicate ecosystem of Korea. Efficiency in planning and design was necessary to minimize the environmental impact of the original construction. However, the ordinal design methods have limited the data processing by the massive scale of the project of golf course development. Conventional design methods did not have a proper tool for alternative plans on pre-estimation of landscape destruction or minimizing of the environmental impact. Therefore, advanced computerized techniques need to be adapted for golf course design to solve the problems concerning the environmental impacts. Geographic information system (GIS) was applied on the process of geographical data input and analysis through the final outputs. Simulation works by the total database management enable the pre-investigation of the design In view of an assessment of environmental impacts. It is also possible to evaluate plans easily and propose the alternatives properly. Precise quantity calculation of engineering works by computer system should be guaranteed scientific, economic, and environmentally-sound.

• Journal of KIISE:Software and Applications
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• v.28 no.12
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• pp.910-920
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• 2001

We developed a SIFC(Slice-based Information Flow Graph) For modeling the information flow on program on the basis of the information flow of a data tokens on program slices. Then we defined a SCM(Slice-based Complexity Measure) for measuring the program complexity by measuring the complexity of information flow on SIFG, We showed that, according to Zuse's approach, it assumed ordinal scale based on atomic modifications on SIFG and that it was additive to binary operation MBSEQ and that it was not additive to binary operation MBALT but satisfied Weyuker's 9th axiom. Also based on comparison with the existing measures, we showed that SCM could measure not only the control and data flow in program but also the physical size of program.

• Journal of Korean Academy of Nursing
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• v.13 no.3
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• pp.106-118
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• 1983

The main purpose of this study is to systematically classify words indicating pain in terms of their ranks in each subclass. This study is a part of developing a Korean Pain Measurement Tool. This study didnot include exploration of each word's dimension such as sensory or affective. Eighty three Korean words tentatively classified in 19 subclasses in previous study were used for this study. At least three to six words were included in each subclass and the words were randomly placed in which each subject indicates their rank of pain degree. One hundred and fifty nursing students and one hundred clinical nurses were requested to indicate the rank of each word. One hundred and sixteen students and eighty three nurses completed the ratings for analysis. The data were collected from June 1983 to July 1983. The data using ordinal scale were analyzed by Friedman ANOVA to test significant difference between rank means. All of pain words indicated significant rank mean difference in all of 19 subclasses. Some of the words were either cancelled or replaced by other words, or rearranged for their ranks. Subclasses of which words were cancelled were 1) Simple stimulating pain, 2) Punctuate pressure, 3) peripheral nerve pain, 4) radiation pain, 5) punishment-related pain, and 6) suffering-related pain. Subclasses of which words were replaced or rearranged were 1) incisive pressure, 2) constrictive pressure, 3) dull pain, 4) tract pain, 5) digestion-related pain and 6) fear-related pain. Four subclasses such as traction pressure, thermal, cavity pressure, and fatigue- elated pain indicated significant differences among rank means in each subclasses and showed no visible overlaps of the ranks among means. Further research is needed using high level measurement of pain degree of each word and more sophisticated analysis of the pain degrees. Three pain words which would be related to chemical stimulation were newly explored and included as a new subclass. Through this study, the total number of subclasses increases from 19 to 20 and the total number of Korean words in the scale decreases from 83 to 80.

• 재활복지
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• v.18 no.4
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• pp.145-164
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• 2014

The purpose of the study is to examine the relationships of parents' satisfaction towards their children's school education and the demographic variables associated with decision-making on post high school academic completion of parents of the students with disabilities. The Korean Education Longitudinal Study data, which contained the responses of 162 parents of high school students with mild disabilities who enrolled in regular high schools, was used for the study. For data analysis, descriptive statistics, ordinal logistic regression analysis, and chi-square test were used. As a result, provision of college entrance related information/consultation, improvement of academic performance level, collaboration/ communication between the teachers and parents, and overall school education were significantly related to parents' decision-making on their children's post high school academic completion. Also, mothers' educational level showed significant difference in parents' decision-making on their children's post high school academic completion.

• Korean Journal of Radiology
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• v.24 no.4
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• pp.284-293
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• 2023

Objective: To validate a simplified ordinal scoring method, referred to as modified length-based grading, for assessing coronary artery calcium (CAC) severity on non-electrocardiogram (ECG)-gated chest computed tomography (CT). Materials and Methods: This retrospective study enrolled 120 patients (mean age ± standard deviation [SD], 63.1 ± 14.5 years; male, 64) who underwent both non-ECG-gated chest CT and ECG-gated cardiac CT between January 2011 and December 2021. Six radiologists independently assessed CAC severity on chest CT using two scoring methods (visual assessment and modified length-based grading) and categorized the results as none, mild, moderate, or severe. The CAC category on cardiac CT assessed using the Agatston score was used as the reference standard. Agreement among the six observers for CAC category classification was assessed using Fleiss kappa statistics. Agreement between CAC categories on chest CT obtained using either method and the Agatston score categories on cardiac CT was assessed using Cohen's kappa. The time taken to evaluate CAC grading was compared between the observers and two grading methods. Results: For differentiation of the four CAC categories, interobserver agreement was moderate for visual assessment (Fleiss kappa, 0.553 [95% confidence interval {CI}: 0.496-0.610]) and good for modified length-based grading (Fleiss kappa, 0.695 [95% CI: 0.636-0.754]). The modified length-based grading demonstrated better agreement with the reference standard categorization with cardiac CT than visual assessment (Cohen's kappa, 0.565 [95% CI: 0.511-0.619 for visual assessment vs. 0.695 [95% CI: 0.638-0.752] for modified length-based grading). The overall time for evaluating CAC grading was slightly shorter in visual assessment (mean ± SD, 41.8 ± 38.9 s) than in modified length-based grading (43.5 ± 33.2 s) (P < 0.001). Conclusion: The modified length-based grading worked well for evaluating CAC on non-ECG-gated chest CT with better interobserver agreement and agreement with cardiac CT than visual assessment.

• Journal of Veterinary Clinics
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• v.32 no.4
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• pp.324-329
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• 2015

The primary aim of this study was to investigate biosecurity practices in pig farms and to determine the major risk factors associated with PCV2 infection for a sampled swine population in Korea. To this end, we analyzed data from a cross-sectional study of 296 farrow-to-finish farms, which was conducted between March and September 2014 to explore the prevalence of swine disease at farm level. Face-to-face interviews by on-site visit of trained veterinarians were conducted with the farm owners or managers using a standardized questionnaires with information about basic demographical data and management practices. Farms were classified as negative or positive through the use of infection profiles that combined data on serological testing including PCR antigen test result, antibody titer and sero-conversion pattern at each age category taking into account vaccination status. Data were analyzed using multivariate ordinal logistic regression. Results from this study indicated that biosecurity level of the farms was considered not good given low compliance of the biosecurity programs and facilities in the farm: off-site removal of dead stocks (7%), off-site location of storage facility for incoming feeds (12.6%), off-site pick-up location for finishers (19.3%), restrictions on feed supplier vehicles for farm entrance (19.6%), restriction of finisher trucks entering the farm (22.4%), and restriction on manure disposal trucks entering the farm (26.4%). In the final model (n = 255), allowance of finisher truck driver to the pig unit had increased risk of infection (OR = 2.4, 95% CI 1.22-4.67) whereas farms with a sign forbidding the entrance had decreased risk of infection (OR = 0.19, 95% CI 0.10-0.58). Further comprehensive research with larger sample size is required to better understand the multifactorial characteristic that some predisposing risk factors that were not available in this study. To the best knowledge of the authors, this was the first study to use empirical data to report risk factors associated with PCV2 infection in the Korean pig farms. Results from the current study could be used to decide optimal biosecurity measures to reduce the impact of PCV2 infection to farmers and policy makers.