• 대한임상검사과학회지
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• 제41권3호
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• pp.135-139
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• 2009

Pulmonary function test has been know to be greatly affected by body indices, such as sex, age, height, body weight, body surface area (BSA) and body mass index (BMI), so hat this study was focused to see the relationship between body index and flow-volume curves. Subjects were 156 (male 90, female 66) and they were examined for pulmonary function test in terms of body index and correlation/multiple regression analysis of flow-volume curves at Presbyterian Medical Center from March to August, 2009. The followings results after analyzing the correlation between body index and flow-volume curves. Although flow-volume curve FEF25-75% showed close correlation with age, body weight, and body surface area, but not with body mass index. In addition, multiple regression analysis was performed to see how each body index affects flow-volume curve FEF25-75%, and FEF25-75% dispersion was explained as 74.5% with age only, 94.2% with age and height, and 96% with age, height, and sex. Therefore, sex, age and height that are mainly used for predictive formular of pulmonary function test and nomogram were important factors for pulmonary function test itself, and further study must be done for other body index.

• Perspectives in Nursing Science
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• 제9권1호
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• pp.24-35
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• 2012

Purpose: This research was performed to investigate Korean adolescents' body weight perception, appropriate weight change efforts, and factors that influencing these efforts. Methods: The data were obtained from 68,136 adolescents, aged 12~18 years from the 2007 Third Korean Youth' Risk Behavior Web-based Survey. Descriptive statistical analysis and odds ratio were calculated by logistic regression. Results: The distribution of the body mass index differed in boys and girls. The accuracy of body weight perception was shown in the order of the underweight (91.6%), overweigh t (73.3%), normal weight (55.4%), obesity (41.3%) groups. Adolescents with high perceived economic status tended to have a high prevalence of accuracy of body weight perception. The distribution of appropriate weight change efforts according to the actual body mass index showed that girls were trying to lose weight more than boys. The results of a logistic regression analysis regarding appropriate weight change efforts showed differences according to gender, perceived economic status, mother's educational level, and family affluence scale. Conclusion: Appropriate body weight perception and change management plans are needed for Korean adolescents. In addition, active weight change programs have to be established in the adolescents' living environments, such as schools.

• Journal of Preventive Medicine and Public Health
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• 제56권1호
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• pp.59-66
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• 2023

Objectives: The aim of this study was to evaluate the effect of body weight status and sleep duration on the discrete-time hazard of menarche in Korean schoolgirls using multiple-point prospective panel data. Methods: The study included 914 girls in the 2010 Korean Children and Youth Panel Study who were in the elementary first-grader panel from 2010 until 2016. We used a Gompertz regression model to estimate the effects of weight status based on age-specific and sex-specific body mass index (BMI) percentile and sleep duration on an early schoolchild's conditional probability of menarche during a given time interval using general health condition and annual household income as covariates. Results: Gompertz regression of time to menarche data collected from the Korean Children and Youth Panel Study 2010 suggested that being overweight or sleeping less than the recommended duration was related to an increased hazard of menarche compared to being average weight and sleeping 9 hours to 11 hours, by 1.63 times and 1.38 times, respectively, while other covariates were fixed. In contrast, being underweight was associated with a 66% lower discrete-time hazard of menarche. Conclusions: Weight status based on BMI percentiles and sleep duration in the early school years affect the hazard of menarche.

• 운동영양학회지
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• 제25권1호
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• pp.23-29
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• 2021

[Purpose] This preliminary study aimed to develop a regression model to estimate the non-exercise activity thermogenesis (NEAT) of Korean adults using various easy-to-measure dependent variables. [Methods] NEAT was measured in 71 healthy adults (male n = 29; female n = 42). Statistical analysis was performed to develop a NEAT estimation regression model using the stepwise regression method. [Results] We confirmed that age^A, weight^B, heart rate (HR)_average^C, weight × HR_average^D, weight × HR_sum^E, systolic blood pressure (SBP) × HR_rest^F, fat mass ÷ height^2G, gender × HR_average^H, and gender × weight × HR_sum^I were important variables in various NEAT activity regression models. There was no significant difference between the measured NEAT values obtained using a metabolic gas analyzer and the predicted NEAT. [Conclusion] This preliminary study developed a regression model to estimate the NEAT in healthy Korean adults. The regression model was as follows: sitting = 1.431 - 0.013 × (A) + 0.00014 × (D) - 0.00005 × (F) + 0.006 × (H); leg jiggling = 1.102 - 0.011 × (A) + 0.013 × (B) + 0.005 × (H); standing = 1.713 - 0.013 × (A) + 0.0000017 × (I); 4.5 km/h walking = 0.864 + 0.035 × (B) + 0.0000041 × (E); 6.0 km/h walking = 4.029 - 0.024 × (C) + 0.00071 × (D); climbing up 1 stair = 1.308 - 0.016 × (A) + 0.00035 × (D) - 0.000085 × (F) - 0.098 × (G); and climbing up 2 stairs = 1.442 - 0.023 × (A) - 0.000093 × (F) - 0.121 × (G) + 0.0000624 × (E).

• 한국학교보건학회지
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• 제25권1호
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• pp.51-58
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• 2012

Purpose: This study aims to discover the relation between the sleep duration and quality of adolescents and their body mass index. Methods: The study used data obtained through the 2009 online survey on adolescents health behaviors, targeting a total of 75,066 middle and high school students (39,612 of male students and 35,454 of female students). We first performed t-test, ANOVA and Scheffe's test and then the potential variables which was possibly related to the body mass index are determined from the tests. Using the potential variable, we performed the multiple regression analysis to finally identify the relation between the duration and quality of sleep. Results: As a result, the 39.8% of male students and the 46.5% of female students most frequently respond that the sleep duration was less than 6 hours, and 36.4% of male students and the 45.3% of female students respond that the quality of sleep was not good enough. The body mass index of both the male and the female students portionally decreases to their sleep duration, but the better quality of sleep makes their body mass index higher. Conclusion: In conclusion, the body mass index has some notable relationship with the sleep duration and quality for adolescents. It is advised to consider the sleep duration and quality in the business plans for adolescents in order for the prevention of their body mass index.

• 지역사회간호학회지
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• 제24권3호
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• pp.273-281
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• 2013

Purpose: The purpose of this study was to determine gender differences in effects of self-efficacy, exercise benefits and barriers, and demographic factors on the physical activity. Methods: Seventy sedentary office workers, 35 male and 35 female, from a major airline company, completed a questionnaire from March 28 to April 5, 2012. Steps and body mass indices were measured using a CW-700/701 (Yamax) pedometer and Inbody 720 (Biospace), respectively. Data were analyzed using t-test, $x^2$-test, multiple linear regression, and simultaneous quantile regression. Results: For male workers, exercise self-efficacy had a significant effect on physical activity, but only when respondents were at 10%(3,431 steps/day, p=.018) and 25%(4,652 steps/day, p=.044) of the physical activity distribution. For female workers, marital status was significantly related to physical activity, but only when respondents were at 10% (3,537 steps/day, p=.013) and 25%(3,862 steps/day, p=.014) of the physical activity distribution. Conclusion: Quantile regression highlights the heterogeneous effect of physical activity determinants among office workers. Therefore intervention strategies for increasing physical activity should be tailed to genders as well as physical activity levels.

• 산업경영시스템학회지
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• 제43권2호
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• pp.137-145
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• 2020

Various elements of Fabrication (FAB), mass production of existing products, new product development and process improvement evaluation might increase the complexity of production process when products are produced at the same time. As a result, complex production operation makes it difficult to predict production capacity of facilities. In this environment, production forecasting is the basic information used for production plan, preventive maintenance, yield management, and new product development. In this paper, we tried to develop a multiple linear regression analysis model in order to improve the existing production capacity forecasting method, which is to estimate production capacity by using a simple trend analysis during short time periods. Specifically, we defined overall equipment effectiveness of facility as a performance measure to represent production capacity. Then, we considered the production capacities of interrelated facilities in the FAB production process during past several weeks as independent regression variables in order to reflect the impact of facility maintenance cycles and production sequences. By applying variable selection methods and selecting only some significant variables, we developed a multiple linear regression forecasting model. Through a numerical experiment, we showed the superiority of the proposed method by obtaining the mean residual error of 3.98%, and improving the previous one by 7.9%.

• Geomechanics and Engineering
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• 제28권4호
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• pp.359-374
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• 2022

Geology conditions are crucial in decision-making during the planning and design phase of a tunnel project. Estimation of the geology conditions of road tunnels is subject to significant uncertainties. In this work, the effectiveness of a novel regression method in estimating geological or geotechnical parameters of road tunnel projects was explored. This method, called Gaussian process regression (GPR), formulates the learning of the regressor within a Bayesian framework. The GPR model was trained with data of old tunnel projects. To verify its feasibility, the GPR technique was applied to a road tunnel to predict the state of three geological/geomechanical parameters of Rock Mass Rating (RMR), Rock Structure Rating (RSR) and Q-value. Finally, in order to validate the GPR approach, the forecasted results were compared to the field-observed results. From this comparison, it was concluded that, the GPR is presented very good predictions. The R-squared values between the predicted results of the GPR vs. field-observed results for the RMR, RSR and Q-value were obtained equal to 0.8581, 0.8148 and 0.8788, respectively.

• Communications for Statistical Applications and Methods
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• 제31권4호
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• pp.441-457
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• 2024

Semicontinuous data are characterized by a mixture of a point probability mass at zero and a continuous distribution of positive values. This type of data is often modeled using a two-part model where the first part models the probability of dichotomous outcomes -zero or positive- and the second part models the distribution of positive values. Despite the two-part model's popularity, variable selection in this model has not been fully addressed, especially, in high dimensional data. The objective of this study is to investigate variable selection and prediction performance of penalized regression methods in two-part models. The performance of the selected techniques in the two-part model is evaluated via simulation studies. Our findings show that LASSO and ENET tend to select more predictors in the model than SCAD and MCP. Consequently, MCP and SCAD outperform LASSO and ENET for β-specificity, and LASSO and ENET perform better than MCP and SCAD with respect to the mean squared error. We find similar results when applying the penalized regression methods to the prediction of crime incidents using community-based data.

• 대한의생명과학회지
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• 제16권3호
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• pp.169-177
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• 2010

Osteoporosis is a disease that increases the fracture rates and a major cause of increased mortality and morbidity in the elderly people. This study is to determine which components of body composition and metabolic syndrome risk factors are important to bone health, we analysed the relationship among bone mineral density (BMD), body composition and metabolic syndrome risk factors in females. Totally 630 females participated in a medical check-up program (mean age 47 years) were selected for this study. Body composition analysis was performed by segmental bioelectrical impedance method, muscle mass, and percent body fat were measured. We also measured metabolic syndrome risk factors including abdominal obesity, HDL-cholesterol, triglyceride, blood pressure and fasting glucose level. Metabolic syndrome was defined by NCEP-ATP III criteria. The lumbar spine and femoral neck BMD were measured using the dual energy X-ray absorptiometry. Osteopenia and osteoporosis were observed in 180 and 51 persons, respectively. Muscle mass and HDL-cholesterol decreased in osteopenia and osteoporosis groups compared to the control group, and the grade was shown progressively by the symptoms. Significant positive correlation between BMD and muscle mass was observed. Multi variable regression analyses showed that % body fat and muscle mass were independent predictors of BMD after adjustment of age, height and weight. In conclusion, the BMD showed negative correlation with the metabolic and body composition was associated with BMD.