• International Journal of Aeronautical and Space Sciences
• /
• v.14 no.4
• /
• pp.310-323
• /
• 2013

In this paper, the aeroelastic static response of flexible wings with arbitrary cross-section geometry via a coupled CUF-XFLR5 approach is presented. Refined structural one-dimensional (1D) models, with a variable order of expansion for the displacement field, are developed on the basis of the Carrera Unified Formulation (CUF), taking into account cross-sectional deformability. A three-dimensional (3D) Panel Method is employed for the aerodynamic analysis, providing more accuracy with respect to the Vortex Lattice Method (VLM). A straight wing with an airfoil cross-section is modeled as a clamped beam, by means of the finite element method (FEM). Numerical results present the variation of wing aerodynamic parameters, and the equilibrium aeroelastic response is evaluated in terms of displacements and in-plane cross-section deformation. Aeroelastic coupled analyses are based on an iterative procedure, as well as a linear coupling approach for different free stream velocities. A convergent trend of displacements and aerodynamic coefficients is achieved as the structural model accuracy increases. Comparisons with 3D finite element solutions prove that an accurate description of the in-plane cross-section deformation is provided by the proposed 1D CUF model, through a significant reduction in computational cost.

• The Korean Journal of Financial Management
• /
• v.6 no.2
• /
• pp.33-69
• /
• 1989

The Purpose of this study is to test empirically the determinants of capital structure of the Korea Listed Firms. In order to accomplish the purpose of this study, both literature survey and empirical test have been made. For the empirical test, agency and asymmetric information factors as well as traditional ones have been throughly reviewed. Traditional factors tested in this study include firm-size, collateral value of the assets, business risk, tax, non-debt tax shields, and industry effects. Agency and asymmetric information factors include growth opportunities, the percentage of outstanding equity held by inside stockholders, and the number of inside stockholders. From the results of the cross-sectional regression analysis, the adjusted R-square is 1931%, and the overall F-value indicates significance. For the analysis period, the signs of the variables except business risk are as predicted. Firm-size, collateral value of the assets, and business risk significant at the.01-.05 level. In order to determine the influence of industry factors on the financial leverage, a total of 8 dummy variables are added to the regression model. The adjusted R-square inclosed by 4.2% for the first analysis period(1983-1985) and 6% for the second analysis period(1986-1987). This suggests that industry factors are significant in explaining the variations in financial leverage across firms. In order to pursue the influence of agency and asymmetric information factors on the financial leverage, again the cross-sectional regression analysis is done for the middle size firms gruop(n=40). The adjusted R-square increased by 9.8% for the first analysis period(1983-1985) and 6.1% for the total analysis period(1983-1987), and all the signs was as predicted. But both the variables except the number of inside stockholders was not significant.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.1
• /
• pp.100-114
• /
• 1996

In this paper, a new thin-walled beam finite elcment is developed to overmome the difficulties in the analysis of real structures by existing beam elements. The element is formulated by extending Benscoter's assumption and also by adopting the concept of the curvature-based element. It is applicable to the analysis of the beams with arbitrary cross-sectional shapes. The results obtained show that the element is locking-free and the accuracy of the finite element solutions is remarkably improved.

• Transactions of Materials Processing
• /
• v.12 no.7
• /
• pp.631-639
• /
• 2003

Ring rolling process is simulated by using the general-purpose commercial finite element analysis software, MSC.Superform. Because the deforming region is restricted to the vicinity of the roll gap, only a ring segment spanning the roll gap is analyzed in order to save computation time and cost. First, a plain ring rolling of rectangular cross-section is simulated. Comparisons between computation and experiment show good agreement in the cross-sectional configuration of the deformed ring. Then, a profile ring with an external round groove is analyzed. The rolls with and without groove have been analyzed to compare the amount of side spread. It is found that the grooves in the rolls are effective in reducing the amount of side spread.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.14 no.1
• /
• pp.2557-2569
• /
• 1972

Hydraulic computations to determine the elevation of canal bottom and mater surface for box type concrete culverts are discussed. Velocity and cross sectional area of flow are computed from Manning's formula. Aad then head loss and velocity head are considered to determine the elevation of bottom and water surface. For stress analysis, 13.5 ton live load and earth pressure are considered. Also longitudinal stress of box culverts is checked.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.3
• /
• pp.203-209
• /
• 2012

In this paper, cross-sectional stiffnesses, static stresses, and dynamic natural frequencies are analyzed to examine the structural performance of wind turbine composite blades. The material properties of composite materials are based on room-temperature and radiation curing processes. The cross-sectional stiffnesses of composite blades are calculated by applying a beam theory with solid-profile cross sections. The wind turbine blades are modeled with a finite element program, and static analyses are carried out to check the maximum displacement and stress of the blades. In addition, dynamic analyses are performed to predict the rotating natural frequencies of the composite blades including the effects of centrifugal force. By comparing these analysis results, mainly owing to the material properties of composite materials, an improvement in the structural performance of the blades according to the curing process is investigated.

• Journal of Radiation Protection and Research
• /
• v.47 no.2
• /
• pp.67-76
• /
• 2022

Background: We conducted a cross-sectional study of residents within and outside Fukushima Prefecture to clarify their perceptions of the need for smartphone applications (apps) for explaining exposure doses. The results will lead to more effective methods for identifying target groups for future app development by researchers and municipalities, which will promote residents' understanding of radiological situations. Materials and Methods: In November 2019, 400 people in Fukushima Prefecture and 400 people outside were surveyed via a web-based questionnaire. In addition to basic characteristics, survey items included concerns about radiation levels and intention to use a smartphone app to keep track of exposure. The analysis was conducted by stratifying responses in each region and then cross-tabulating responses to concerns about radiation levels and intention to use an app by demographic variables. The intention to use an app was analyzed by binomial logistic regression analysis. Text-mining analyses were conducted in KH Coder software. Results and Discussion: Outside Fukushima Prefecture, concerns about the medical exposure of women to radiation exceeded 30%. Within the prefecture, the medical exposure of women, purchasing food products, and consumption of own-grown food were the main concerns. Within the prefecture, having children under the age of 18, the experience of measurement, and having experience of evacuation were significantly related to the intention to use an app. Conclusion: Regional and individual differences were evident. Since respondents differ, it is necessary to develop and promote app use in accordance with their needs and with phases of reconstruction. We expect that a suitable app will not only collect data but also connect local service providers and residents, while protecting personal information.

• Progress in Superconductivity and Cryogenics
• /
• v.8 no.1
• /
• pp.9-14
• /
• 2006

Sample preparation plays a critical role in microstructure analysis using TEM. Although TEM specimen has been usually prepared by jet-polishing or Ar-ion beam milling technique. these methods could not be applied to YBCO CC which is composed of IBAD or RABiTS substrates, several buffet layers, and YBCO superconducting layer because of big difference in mechanical strengths between the metallic phase and oxide phases. To obtain useful cross-sectional information such as interface between the phases or second phases in YBCO CC, it is prerequisite to secure the large area of thin section in the cross-sectional direction. The superconducting layer or the buffer layers are relatively weak and fragile compared to the metallic substrate such as Ni-5wt%W RABiTS of Hastelloy-based IBAD, and preferential removal of weak ceramic phases during polishing steps makes specimen preparation almost impossible. Tripod polisher and small jig were home-made and employed to sample preparation. The polishing angle was maintained <$1^{\circ}$ throughout the polishing steps using 2 micrometers attached to the tripod plate. TEM specimens with large and thin area could be secured and used for RABiTS/IBAD substrate analyses. In some cases, additional Ar-beam ion milling with low beam current and impinging angle was used for less than 30 sec. to remove debris or polishing media attacked to the specimens.

• Korean Journal of Legislative Studies
• /
• v.23 no.2
• /
• pp.147-177
• /
• 2017

Although a number of empirical studies found that political ideology plays a significant role in Korean elections, they entirely rely on cross-sectional data analysis. In contrast to previous research, this study investigates the effects of ideology in the 2012 Korean presidential election through standard panel data analysis. Specifically, using "EAI Panel Study, 2012", the effects of ideology on both candidate evaluation and vote choice were examined via fixed effects, random effects, and pooled regression analysis. And the results from applying the two most popular models of ideological voting, the proximity model and the directional change model were also compared. The results show that candidate evaluations and vote choice during the election (April, 2012- December, 2012) were significantly influenced by the ideological difference between voters and candidates, independent from partisanship and other standard socio-demographic factors. And this ideological voting during the election seems better captured by the directional change model than by the proximity model.

• Nutrition Research and Practice
• /
• v.15 no.1
• /
• pp.80-94
• /
• 2021

BACKGROUND/OBJECTIVES: Recent studies have reported chocolate consumption has beneficial effects on blood pressure, obesity, and dyslipidemia, which are components of metabolic syndrome (MetS). However, evidence regarding these relationships in Asia is limited. The aim of this study was to investigate relations between chocolate consumption and MetS in Korea. SUBJECTS/METHODS: Study subjects were 6,982 adults aged 19-64 years free of major chronic diseases that participated in the 2014-2016 Korea National Health and Nutrition Examination Survey. Information on chocolate consumption was obtained using food frequency questionnaires. For primary analysis, subjects were divided into two groups: non-consumer (n = 3,741, 53.6%); consumer (n = 3,241, 46.4%). In order to investigate dose-response effects on MetS, chocolate consumers were divided into quartiles based on amounts consumed: Q1 (n = 789, 24.3%); Q2 (n = 837, 25.8%); Q3 (n = 863, 26.6%); Q4 (n = 752, 23.2%) in second analysis. RESULTS: Chocolate consumers; 1) were more physically active(P < 0.0001); 2) less likely to smoke(P < 0.0001); 3) paid more attention to food nutrition labels (P < 0.0001), and 4) had healthier dietary patterns, that is, they consumed vegetables, fruits, and dairy products more frequently(P < 0.0001) than non-consumers. Furthermore, chocolate consumers had a 30% lower risk of MetS (odds ratio, 0.70; 95% confidence interval, 0.58-0.86; P = 0.0005). However, dose-response effects between chocolate intake and MetS was not found by secondary analysis after excluding non-consumers. CONCLUSIONS: In conclusion, chocolate consumers had healthier lifestyles and dietary patterns and a lower prevalence of MetS than non-consumers, as determined by our primary analysis. Although dose-response effects were not found to be significant among chocolate consumers during secondary analysis, the patterns were partially similar. This cross-sectional finding shows chocolate consumption does not increase the risk of MetS. The prospective studies and intervention trials in Korea are needed to confirm this cross-sectional finding.