• Progress in Superconductivity and Cryogenics
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• v.17 no.4
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• pp.16-20
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• 2015

We investigated optical properties of an electron-doped copper oxide high temperature superconductor, $Pr_{0.85}LaCe_{0.15}CuO_4$ (PLCCO) single crystal. We obtained the optical conductivity from measured reflectance at various temperatures. We found our data contained c-axis longitudinal optical (LO) phonon modes due to miscut and intrinsic lattice distortion. We applied an extended Drude model to study the correlations between charge carriers in the system. The LO phonons appear as strong sharp peaks in the optical scattering rate. We tried to remove the LO phonon modes by using the energy loss function, which also shows the LO phonons as peaks, and could not remove them completely. We extracted the electron-boson spectral density function using a generalized Allen's formula. We observed that the resulting electron-boson density show similar temperature dependence as hole-doped cuprates.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.27-31
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• 2011

In this paper, the electron transport characteristics in $CF_4$ has been analysed over the E/N range 1~300[Td] by a two-term approximation Boltzmann equation method and by a Monte Carlo simulation. The motion has been calculated to give swarm parameters for the electron drift velocity, longitudinal diffusion coefficient, the ratio of the diffusion coefficient to the mobility, electron ionization and attachment coefficients, effective ionization coefficient, mean energy, collision frequency and the electron energy distribution function. The electron energy distribution function has been analysed in $CF_4$ at E/N=5, 10, 100, 200 and 300[Td] for a case of the equilibrium region in the mean electron energy and respective set of electron collision cross sections. The results of Boltzmann equation and Monte Carlo simulation have been compared with experimental data by Y. Nakamura and M. Hayashi. The swarm parameter from the swarm study are expected to serve as a critical test of current theories of low energy electron scattering by atoms and molecules, in particular, as well as crucial information for quantitative simulations of weakly ionized plasmas.

• Child Health Nursing Research
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• v.7 no.4
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• pp.451-460
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• 2001

Congenital heart disease is now estimated to be the most prevalent chronic illness in children. The overall purpose of study is to enhance our understanding of mother's perception of family stress, perceived social support, and coping who has a child newly diagnosed with congenital heart disease. In this investigation, the relationship between family stress, perceived social support, and coping within the context of a acute, non life- threatening chronic illness in the situation of newly diagnosed as Rolland's typology of chronic illness. The study employed data from a subset of a large longitudinal study, children's chronic illness: parents and family adaptation conducted by M. McCubbin (5 R29 NR02563) which was funded by the NIH. The subject for this study were 92 mothers who have a child under age 12 who was newly diagnosed with congenital heart disease within the last 3-4 months. Results form correlational and regression analysis revealed that perceived social support operated as a resiliency factor between family stress and coping of mothers. Child and family characteristics appeared to be important predictors of perceived social support and mother's coping. Therefore, the findings provide an incremental contribution to the explanation of effects for perceived social support and may challenge resiliency model in previous literature. Further, these findings suggest that perceived social support and coping are both influencing in the resiliency of relatively high risk groups of families who has a child with congenital heart disease.

• Korean Journal of Occupational Health Nursing
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• v.18 no.2
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• pp.153-164
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• 2009

Purpose: This study investigates the relationship between job stress, depression, health-related behavior and type A behavior patterns among male workers at a steel factory. Methods: The study was done on 171 male workers, using the structured questionnaire. The data were collected in April, 2009 and analyzed by descriptive statistics, t-test, ANOVA, and pearson correlation coefficient. Results: The results showed that 65.5% of workers were under moderate stress, 25.7% high stress and 0.6% extremely high stress. The overall score of these workers' occupational stress was 41.9, lower than the Korean workers' average. Occupational stress was correlated with depression, type A behavior patterns, a very poor physical condition without sufficient sleep. Conclusion: Stress management program is strongly needed for these subjects working over 45 hours a week, with a very poor subjective physical condition, insufficient sleep, type A behavior patterns and signs of severe depression. Further longitudinal study is recommended to show the effect of such worker's stress management program to mitigate job-related stress.

• Journal of Family Resource Management and Policy Review
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• v.15 no.1
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• pp.29-49
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• 2011

Social capital theory provides a robust framework for analyzing economic well being. The purpose of this study was to investigate the effects of social capital on the economic satisfaction of retirees in Korea. The data from the first wave of KLoSA(Korean Longitudinal Study of Aging) were used(n=1,628). SPSS 12.0 was used for descriptive statistics and multiple regression analysis. The major findings were as follows: First, after controlling for gender, age, region, housing tenure, and personal income, the social capital of the retirees, including cognitive social capital(trust and reciprocity) and structural social capital(emotional and economic familial support, and a well-developed social network), contributes to increases in their economic well-being. Second, the degree of effect social capital has on well-being varied by gender and age; the effect was also different according to gender, regardless of the person's age. These empirical results provide a basis for the institution of policies that help bolster economic wellbeing for retirees by creating conditions that increase social capital in this group.

• Computers and Concrete
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• v.14 no.1
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• pp.1-18
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• 2014

The addition of steel fibers in concrete mixture is recognized as a non-conventional mass reinforcement scheme that improves the torsional, flexural, and shear behavior of structural members. However, the analysis of fiber reinforced concrete beams under combined torsion, bending, and shear is limited because of the complicated nature of the problem. Therefore, nonlinear 3D finite element analysis was conducted using the "ANSYS CivilFEM" program to investigate the behavior of fiber reinforced concrete L-beams. These beams were tested at different reinforcement schemes and loading conditions. The reinforcement case parameters were set as follows: reinforced with longitudinal reinforcement only and reinforced with steel bars and stirrups. All beams were tested under two different combined loading conditions, namely, torsion-to-shear ratio (T/V) = 545 mm (high eccentricity) and T/V = 145 mm (low eccentricity). Eight intermediate L-beams were constructed and tested in a laboratory under combined torsion, bending, and shear to validate the finite element model. Comparisons with the experimental data reveal that the program can accurately predict the behavior of L-beams under different reinforcement cases and combined loading ratios. The ANSYS model accurately predicted the loads and deformations for various types of reinforcements in L-beams and captured the concrete strains of these beams.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.2
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• pp.141-149
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• 2004

In this study, smoke movement in tunnel fire with natural and longitudinal ventilation systems has been investigated. Reduced-scale experiments were carried out under the Froude scaling using 14.55kW fire source with a wick and experimental data is obtained with 1/18 model tunnel test. Temperature profiles were measured under the ceiling and vertical direction along the center of the tunnel and poisonous gas was measured at emergency exit point. The results show that refuge time for 225m intervals of emergency exit in case of natural ventilation systems is 256 seconds and critical velocity for sufficient back-layer prevention is 2.8m/s for fire strength of 20MW.

• Korean Medical Education Review
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• v.16 no.2
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• pp.77-87
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• 2014

The purpose of this study was to investigate the influence of demographic data, academic demand, perfectionism, and academic failure tolerance on academic burnout of medical and graduate students at Yeungnam University. A mixed method study was conducted. Fourteen students participated in a focus group interview and 302 students, including 151 medical students and 151 graduate students, completed a survey, which addressed the factors of academic burnout, academic demand, perfectionism, and academic failure tolerance. There were significant differences in the academic burnout by age and year in school. The 2nd year medical & graduate students experienced significantly higher academic burnout than the other students. Multiple regression analysis revealed that academic burnout of medical and graduate students was significantly affected by academic demand (p<0.001), self-oriented and socially-prescribed perfectionism (p<0.001, p<0.01), and feeling and behavior, which were sub-factors of academic failure tolerance (p<0.05, p<0.01). It is suggested that comparative studies with other student groups, a longitudinal study of medical and graduate students, and a prospective study of coping styles and methods of preventing academic burnout need to be conducted.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.97-100
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• 2008

Various flyers in nature have attracted great interests with a recent need for developing versatile and small-size flight vehicles. In the present study, we focus on the flying fish which has been observed to glide a long distance just above a seawater surface. Since previous studies have depended on the field observation or measurement of the physical parameters only, quantitative data of the flying fish flight has not been provided so far. Therefore, we evaluate the wing performance of the flying fish in gliding flight by directly measuring the lift, drag and pitching moment on real flying fish models (Cypselurus hiraii) in a wind tunnel. In addition, we investigate the roles of wing morphology like the enlarged pectoral and pelvic fins, and lateral dihedral angle of pectoral fins. With both the pectoral and pelvic fins spread, the lift-to-drag ratio is larger and the longitudinal static stability is enhanced than those with the pelvic fins folded. From the glide polar, we find that the wing performance of flying fish is equivalent to those of medium-size birds like the petrel, hawk and wood duck. Finally, we examine the effect of water surface underneath the flying fish and find that the water surface reduces the drag and increases the lift-to-drag ratio.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.773-777
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• 2011

Conventional ultrasonic thickness measurement is to be considered as the assumption that the ultrasonic velocity is known. In actual applications the velocity is often not well known and access is often limited to one side. This paper aims at determining the ultrasonic velocity and thickness of plates with parallel or wedged surfaces using contact measurements made on one surface only. For wedged plates the thickness at one point and the wedge angle are determined. Equations are used for determining the ultrasonic velocity, thickness and wedge angle of the plate based on the times-of-flight measured by two contact transducers coupled to one surface. The time-of-flight of the obliquely reflected longitudinal wave echo was measured as a function of the separation between the two transducers. In addition, a simulation was made for comparing the experimental data and a FEM image. Experiments and simulations were performed on flat and wedged plates of aluminium materials; the calculated results for the unknown quantities are generally agreed with them to some degree.