• Wind and Structures
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• 제37권3호
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• pp.179-189
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• 2023

Multiple studies conducted in the past evaluated the conductor response under one tornado wind field, while the performance of transmission lines under different tornado wind fields still remains unknown. Thus, the objective of this paper is to estimate the variation in the conductor's critical longitudinal and transverse reactions under different tornado wind fields, as well as providing the corresponding critical tornado configurations. The considered full-scale tornadoes are the Spencer, South Dakota, 1998, the Stockton, Kansas, 2005 and the Goshen County, Wyoming, 2009. Computational Fluid Dynamics (CFD) simulations were previously conducted to develop these wind fields. All tornadoes have been rescaled to have a common velocity matching the upper limit of the F2 Fujita scale. Eight conductor systems, each including six spans, are considered in this paper. For each conductor, parametric studies are conducted by varying the location of the three tornado wind fields relative to the tower of interest, therefore the peak reactions associated with each tornado are determined. A semi-analytical closed-form solution, previously developed and validated, is used to calculate the reactions. The study conducted in this paper can be divided into two parts: In the first part, a parametric study considering a wide range of tornado locations is conducted. In the second part, the parametric study focuses on the tornado location leading to the critical tangential velocity on the tower. Based on this extensive parametric study, a critical tornado defined as the Design Tornado and its critical locations, tornado distance R = 125 m, tornado angle 𝜃 = 15° and 30°, are recommended for design purposes.

• 아동학회지
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• 제37권5호
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• pp.33-52
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• 2016

Objective: This study aimed to investigate the trajectory of maternal parenting stress during infancy according to the employment status of mothers when each year's depression was controlled and examine the longitudinal effects of parenting stress on affective parenting and socioemotional developmental outcomes for preschoolers. Methods: Using latent growth modeling, the first 4 waves of panel data collected from 2,078 mothers and their babies were analyzed. This nationwide data was provided from the 2008 Panel Study on Korean Children, conducted by the Korea Institute of Child Care and Education. Results: First, maternal parenting stress showed a linear increasing pattern, and there were individual differences in intercept and slope. Second, when each year's maternal depression was controlled, the intercept of parenting stress was lower, but the rate of increase was higher. In multiple group analyses, this increasing pattern of parenting stress was significant only in unemployed mothers. Lastly, the increase of unemployed mothers' parenting stress had direct effects on child emotionality and peer interaction and had an indirect effect on child peer interaction (mediated by affective parenting). Conclusion: The current study verified that the longitudinal effects of increasing parenting stress of unemployed mothers on affective parenting and child socioemotional development when maternal depression level was controlled. These results imply that we need to pay more attention to emotional health and resources of unemployed mothers and provide them with social support as well as employed mothers.

• Human Ecology Research
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• 제62권2호
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• pp.249-259
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• 2024

The purpose of this study was to identify the longitudinal mediating effects of peer attachment on the relationship between psychological school environment and children's sense of community. Data on 1,088 children were obtained from the 10^th, 11^th, and 13^th Panel Study on Korean Children in the 3rd 4th, and 6th grades. The data were analyzed using descriptive statistics, Cronbach's α, Pearson's correlation, a latent growth model, and a multivariate latent growth model. All analyses were conducted in SPSS 25.0 and AMOS 23.0. The principal results were as follows. First, children's peer attachment gradually decreased over time. Moreover, individual differences existed in the initial values and rates of change. Second, the psychological school environment in the 3rd grade positively influenced children's initial peer attachment, which then exerted a positive impact on children's sense of community in the 6th grade. Second, the psychological school environment in the 3rd grade negatively influenced children's rates of change, which also exerted a positive impact on children's sense of community in the 6th grade. Finally, the initial value and rates of change of peer attachment were significant mediating effects of the relationship between the psychological school environment in the 3rd grade and children's sense of community in the 6th grade. The findings highlight the necessity of creating a psychological school environment that develops peer attachment and a sense of community among children.

• 대한치과의사협회지
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• 제51권9호
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• pp.494-500
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• 2013

Recently, several researches indicated the relationship between oral condition and respiratory disease such as pneumonia and chronic obstructive pulmonary disease (COPD). Respiratory disease is known as common chronic disease in the elderly increasing mortality and morbidity. In this study, we have reviewed the association between oral disease and respiratory disease in the elderly. The related data were searched and collected from abroad and domestic studies. The studies included the randomized controlled clinical trials (RCTs), longitudinal, cohort, case-control, and systematic review studies. With the data from the studies, we concluded that poor oral hygiene or periodontal disease can influence the pneumonia in the elderly. Further studies will be needed to investigate the association between oral disease and COPD.

• 대한치과의사협회지
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• 제15권1호
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• pp.41-45
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• 1977

For biometric study on the widlth of mouth in singaporian the author measured the transversal width of mouth, Longitudinal width of mouth and Interdental space in 652 cases of the total cases 317 were male (chinese 235. malay50, Indian 32) and 335 Female (Chinese 260, malay 53. Indian 22) and Ages ranged from 5 to 25 yeass old. The fallowing result was obtained. 1) In Adult, transversal width of mouth was 54. 20±0.22mm in male, 53.00±0.10mm in female and 40.03±0.26mm in male, 39.39±0.30mm in female of children. 2) In Abult, Longitudinal width of mouth was 52.00±0.12mm in male, 48.40±0.15mm in female and 44.50±0.13mm in male 44.20±0.30mm in female of children. 3) In Adult, Interdental Space (anterior teeth) was 44.20±0.15mm in male. 44.00±0.20mm in Fmale and 38.40±0.15mm in male, 37.17±0.21mm in Female of Children.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.711-716
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• 2003

This study considers the implementation issues of the inter-vehicle communication system for the vehicle platoon experiments via a testbed. The testbed, which consists of three scale vehicles and one RCS(remote control station), is developed as a tool for functions evaluation between simulation studies and full-sized vehicle researches in the previous study. The cooperative communication of the vehicle-to-vehicle or the vehicle-to-roadside plays a key role for keeping the relative spacing of vehicles small in a vehicle platoon. The static platoon control, where the number of vehicles remains constant, is sufficient for the information to be transmitted in the suitably fixed interval, while the dynamic platoon control such as merge or split requires more flexible network architecture for the dynamical coordination of the communication sequence. In this study, the wireless communication device and the reliable protocol of the flexible network architecture are implemented for our testbed, using the low-cost, ISM band transceiver and the 8-bit microcontroller.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 국제학술회의
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• pp.287-300
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• 2008

Airflow distributions along tunnel and over the cross section are critical in selecting installation location of the velocity monitor to obtain the representative data for ventilation as well as fire safety systems. This paper aims at performing CFD and on-site studies to analyze the longitudinal and cross-sectional distributions of the air velocity in tunnels employing longitudinal and semi-transversal ventilation systems. This study can ultimately contribute to selecting the monitor type as well as the optimal installation locations in vehicle tunnel.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2003년도 추계학술발표논문집
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• pp.209-216
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• 2003

There are two kinds of controllers in a continuous process system. One is for tension control of a moving web and the other for lateral motion control. The inter-connection between tension and lateral behaivior of web has not yet been considered in the analysis of web dynamics and designing of control stragagies. But the effect of tension variation on the lateral motion of a moving web is observed in the most manufacturing systems. In this paper, experimental studies was carried out to find out the inter-correlation between tension and lateral motion of a web using a 3-span web transport system which consists of two displacement type guiders. As a result, it was found that there are typical operating conditions that tension and lateral motion are correlated each other.

• Advances in nano research
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• 제9권2호
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• pp.83-90
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• 2020

This research investigates the effect of single walled carbon nanotubes (SWCNTs) dimensions in terms of diameter on the mechanical properties (longitudinal and transverse Young's modulus) of the simulated nanocomposites by molecular dynamics (MDs) method. MDs utilized to create nanocomposite models consisting of five case studies of SWCNTs with different chiralities (5, 0), (10, 0), (15, 0), (20, 0) and (25, 0) as the reinforcement and using polymethyl methacrylate (PMMA) as the common matrix. The results show that with increasing of SWCNTs diameter, the mechanical and physical properties increase. It is important that with the increasing of SWCNTs diameter, density, longitudinal and transverse Young's modulus, shear modulus, poisson's ratio, and bulk modulus of simulated nanocomposite from (5, 0) to (25, 0) approximately becomes 1.54, 3, 2, 1.43, 1.11 and 1.75 times more than (5, 0), respectively. Then to validate the results, the stiffness matrix is obtained by Materials studio software.

• 식물분류학회지
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• 제37권4호
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• pp.351-361
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• 2007

In angiosperms, leaves typically develop as three-dimensional structure with dorsoventral, longitudinal, and lateral axes. We have shown that the control of two axes of leaves, longitudinal and lateral axis, can be genetically separable, and four classes of genes are responsible for the polar cell expansion and polar cell proliferation in Arabidopsis. In monocots, unifacial leaf, in which leaf surface consists only of abaxial identity, has been evolved in a number of divergent species. The unifacial leaves provide very unique opportunities for the developmental studies of the leaf axes formation in monocots, because their leaf polarities are highly disorganized. In addition, the mechanism of the parallel evolution of such drastic changes in leaf polarities is of interest from an evolutionary viewpoint. In this article, we describe our recent approaches to reveal the mechanism of unifacial leaf development and evolution, including recent advances in the leaf polarity specification in angiosperms.