• Journal of Korean society of Dental Hygiene
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• v.21 no.5
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• pp.655-666
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• 2021

Objectives: A systematic review and a meta-analysis were performed investigate the factors related to turnover intention of dental hygienists in Korea. Methods: Literature between 2000 and January 2021 were used to support the meta-analysis, which focused on 21 factors extracted from 50 articles using a random effects model. The correlation coefficient, r, in the effect size was calculated. Results: Substantial literature was published after 2011 (76%); in academic journals (74%); and targeted nonmetropolitan areas (40%). Lawler's turnover intention tool was used in several studies. The effect size for each ecosystem was in the order of microsystem (r=0.325), mesosystem (r=0.307), macrosystem (r=0.259), exosystem (r=0.176), and individuals (r=0.171). The random-effects model indicated an overall average of r=0.311. The factor that showed a large effect size in relation to turnover intention was organizational commitment of the microsystem (r=-0.594). Furthermore, mesosystem reward (r=- 0.416), microsystem burnout (r=0.464), job stress (r=0.408), and job satisfaction (r=-0.405) were identified as other major factors. Conclusions: To lower the turnover rate of dental hygienists, it is important to focus on factors belonging to the microsystem, and mesosystem reward.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.1
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• pp.54-64
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• 1991

To accurately estimate the rate of sediment transport in shallow water bodies, it is necessary to investigate the irregular waves transformation characteristics and nearshore currents produced by random sea waves. Most of studies on numerical models for nearshore currents are based on the theory of monocromatic waves and thus, very few nearshore models take into account the effect of irregularities in the hight, period and directional spreading of incident waves. The numerical simulation model for nearshore currents used in this paper considers the effect of irregularities of incident waves, based on Individual Wave Analysis. The computational results are compared and shown in a reasionable agreement with the experimental data.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1439-1448
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• 2013

The analysis of variance for randomized block design or two way classification data is well known. In this paper, particularly, we considered two stage nested design in which the levels of one factor is not identical for different levels of another factor. We investigate the structural properties of two stage nested design and the properties of error sum of squares for random effect model. For the application of two way nested design, we consider two-period crossover design which is used commonly for the equivalence test to bio-similar product. The confidence interval estimation of the difference of two population means in the crossover design is discussed based on statistical package SPSS.

• Physical Therapy Rehabilitation Science
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• v.11 no.3
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• pp.304-310
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• 2022

Objective: Mild cognitive impairment (MCI) is a condition in which cognitive and executive functions are reduced, and older adults with MCI are ten times more likely to develop dementia than healthy older adults. Expression of brain-derived neurotrophic factor (BDNF) through aerobic exercise is associated with increased cognitive and executive functions. in this review, randomized controlled trials (RCTs) on the effects of aerobic exercise on BDNF in individuals with mild cognitive impairment are summarized and qualitatively and quantitatively analyzed to suggest the necessity of aerobic exercise. Design: a systematic review and meta-analysis. Methods: RCTs were searched for changes in BDNF through aerobic exercise using four international databases. Quality assessment and quantitative analysis were performed using RevMan 5.4. Quantitative analysis was quantified with a standardized mean difference (SMD) and presented as a random effect model. Results: Three RCTs evaluated BDNF in 123 patients with MCI. There was a significant improvement in the experimental group that performed aerobic exercise compared to the control group. The results analyzed using the random effects model were SMD = 0.48. Conclusions: In this review, we reported the effects and mechanisms of aerobic exercise in individuals with MCI. As a result of synthesizing RCTs that performed aerobic exercise, a significant increase in BDNF was confirmed.

• Physical Therapy Rehabilitation Science
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• v.12 no.2
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• pp.115-122
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• 2023

Objective: A previous study reported that cardiovascular training (CT) decreased interleukin-6 (IL-6), a pro-inflammatory cytokine with bidirectional effects. However, because of conflicting results of increasing and decreasing IL-6 levels in stroke patients, it is essential to clarify the effects of CT on IL-6 levels in this population. Therefore, this review aimed to investigate the effects of CT on IL-6 levels in stroke patients through a meta-analysis of randomized controlled trials (RCTs), synthesizing and analyzing the effects qualitatively and quantitatively. Design: A systematic review and meta-analysis of randomized controlled trials. Methods: In this review, conducted in April 2023, electronic databases (Web of Science, CINAHL, Embase, MEDLINE, Google Scholar) were searched to ascertain the effects of CT on IL-6 levels in stroke patients. For qualitative evaluation, ReVMan, provided by the Cochrane Group, was used, and for quantitative evaluation, a random-effects model and SMD (Standardized Mean Difference) were used. Results: Three RCTs measured IL-6 in 117 patients with stroke. The experimental group to which CT was applied showed no significant change compared to the control group.The result of analysis using the random effect model is SMD=-0.23; 95% confidence interval, -0.66 to 0.20. Conclusions: CT does not affect IL-6 levels in stroke patients. These results suggest that CT can be applied regardless of its positive or negative effect on IL-6 levels in stroke patients.

• Communications for Statistical Applications and Methods
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• v.27 no.3
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• pp.349-363
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• 2020

Penalized spline is a suitable nonparametric approach in estimating mean model in small area. However, application of the approach in informative sampling in a published article is uncommon. We propose a semiparametric mixed-model using penalized spline under informative sampling to estimate mean of small area. The response variable is explained in terms of mean model, informative sample effect, area random effect and unit error. We approach the mean model by penalized spline and utilize a penalized spline function of the inclusion probability to account for the informative sample effect. We determine the best and unbiased estimators for coefficient model and derive the restricted maximum likelihood estimators for the variance components. A simulation study shows a decrease in the average absolute bias produced by the proposed model. A decrease in the root mean square error also occurred except in some quadratic cases. The use of linear and quadratic penalized spline to approach the function of the inclusion probability provides no significant difference distribution of root mean square error, except for few smaller samples.

• Journal of Mechanical Science and Technology
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• v.19 no.6
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• pp.1280-1289
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• 2005

This paper presents the effects of corrosion environments of failure pressure model for buried pipelines on failure prediction by using a failure probability. The FORM (first order reliability method) is used in order to estimate the failure probability in the buried pipelines with corrosion defects. The effects of varying distribution types of random variables such as normal, lognormal and Weibull distributions on the failure probability of buried pipelines are systematically investigated. It is found that the failure probability for the MB31G model is larger than that for the B31G model. And the failure probability is estimated as the largest for the Weibull distribution and the smallest for the normal distribution. The effect of data scattering in corrosion environments on failure probability is also investigated and it is recognized that the scattering of wall thickness and yield strength of pipeline affects the failure probability significantly. The normalized margin is defined and estimated. Furthermore, the normalized margin is used to predict the failure probability using the fitting lines between failure probability and normalized margin.

• 한국노년학
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• v.29 no.4
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• pp.1413-1425
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• 2009

The objective of the work is to analyze the factors affecting on changes in filial piety responsibility expectation. For the analysis, this study focuses on the two factors-aging effect and cohort effect. This work analyzes the 4 wave Hallym Aging Panel Data with random intercept model. In the study cohort is divided by the criteria of birth year 1940. and the former cohort is called colony-war cohort and the latter cohort is called industrialization-democratization cohort. The results are in following. First, older cohort shows higher filial piety responsibility expectation score than younger cohort. Second, age shows no relationship with filial responsibility expectation score. Third, male and resident in rural area shows higher score. Forth income, year of schooling, and subjective health show negative relationship with responsibility score.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.53-66
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• 1990

Rainfall is a phenomenon that shows a high variability both in space and time, Hy drologists are usually interested in the description of spatial distribution of rainfall over watershed. The theory of Kriging, generalized covariance technique using nonstationary mean in the regions under orographic effect, was chosen to construct random surface of total storm depth. For the constructed random surface, the double Fourier analysis of the total storm depths was performed, and the principal harmonics of storm were determined. The local component, or storm residuals was obtained by subtracting the periodic component of the storm from total storm depths. It is assumed that the residuals are a sample function of a homogeneous random field. This random field can be characterized by an isotropic one dimensional autocorrelation function or its corresponding spectral density function. Under this assumption, this study proposed a theorectical model for spectral density function adapted to two watersheds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.286-293
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• 2003

The unsteady flow characteristics and associated blade tonal noise of a cross-flow fan are predicted by computational methods. The incompressible Navier-Stokes equations are time-accurately solved for obtaining the pressure fluctuations between the rotating blades and the stabilizer. and the sound pressure is predicted using Curie's equation. The discrete noise characteristics of three impellers with a uniform and two random pitch (type-A and -B) blades are compared by their SPL (Sound Pressure Level) spectra. and the frequency modulation characteristics of the BPF (Blade Passing Frequency) noise are discussed. Besides. a mathematical model is proposed for the prediction of discrete blade tonal noise and is validated with available experimental data. The fan performance is also compared with experimental data. indicating that the random pitch effect does not significantly alter the performance characteristics at ${\phi}$ 〉 0.4