• Science of Emotion and Sensibility
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• v.24 no.4
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• pp.39-52
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• 2021

This study aims to investigate the effect of the coronavirus disease 2019 (COVID-19) epidemic on negative emotions, such as anxiety, depression, fear, and stress, in Korean college students. The study recruited students from J University and conducted interviews across three time points, namely, March 2019, March 2020, and November 2020. For three time points, the participants responded to structured questions about situations they may have encountered and they were asked to summarize their responses. Repeated-measures ANOVAs were performed to examine whether differences exist in negative emotions between time points. Furthermore, polynomial trend analyses were conducted to examine resultant patterns over time. The results revealed that negative emotions displayed significant differences between time points. Moreover, trend analyses revealed a curvilinear pattern, which indicates that negative emotions increased and were then sustained. These findings suggest that negative emotions may continue to become prevalent among college students with the increased impacts of the ongoing COVID-19 pandemic. The study discussed the need for psychological support systems, such as stress management and psychological counseling, for college students.

• Korean Journal of Social Welfare Studies
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• v.42 no.2
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• pp.381-417
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• 2011

The primary goal of this study is to examine the factors that affect how satisfied sexual minorities are with their lives. This study focuses on how sexual minorities perceive social stigma, the social influences involved in its perception, and the effects this perception has. Using stress-coping theory, this study looks at how social stigma, as a perceived stress, affects social support and self-esteem, how the stigma influences the degree to which individuals "come out" in an effort to cope, and the resultant effects of this coping mechanism on life satisfaction. The data used if from a sample of 478 individuals who self identify as gay, lesbian or bisexual. It was collected through an online survey. Using SEM, the quality was evaluated by analyzing the measurement model, and the relationship of the variables included in the theoretical model was verified by analyzing the structural model. The results of this study show that social stigma directly affects the life satisfaction of Korean sexual minorities. It significantly influences the social support they receive(from family and sexual minority peers), and their self-esteem. The degree to which the individual "comes out" is shown to affect life satisfaction as well. In contrast, the mediating effect of heterosexual support is shown to be insignificant. Based on the analyses, practical strategies regarding social stigma, social support, self-esteem, and "coming out" are suggested for sexual minorities. The social stigma should be reduced and society-scaled campaigns promoted in order to improve their level of life satisfaction. In addition, institutional protection should be developed and specialized educational courses on human rights provided which will empower these minorities with self-help mechanisms. Furthermore, issues such as establishing support system and providing a social welfare system for the sexual minority community are discussed.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.681-693
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• 2007

Construction techniques for continuous steel bridges were applied to steel-concrete double composite box girder bridges. Concrete depth and length at the bottom of the steel box in the negative moment region were determined by plastic moment region and negative moment region of the double composite section, respectively. Construction methods, such as crane lifting method, free cantilever method, and incremental launching method were used for the analysis of the construction stage. Two cases of the construction phase were considered and analyzed for the stress resultant of double composite girders. The behavior of the nose-deck elastic system was examined by three-dimensionless parameters, such as the nose length, the unit weight of the launching nose, and the flexural stiffness of the nose. The adoption of the launching nose has become an effective solution in the incremental launching of steel-concrete double composite box girder bridges.

• Journal of Chest Surgery
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• v.26 no.9
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• pp.667-676
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• 1993

Boprosthetic cardiac valves fail from biological and metabolic as well as mechanical reasons, and the limited durability is the main factor of marked withdrawal in their clinical use. Starting the use of bioprosthetic valves in 1976, up to the end of 1992, the consecutive 178 patients have undergone re-replacement of glutaraldehyde-treated xenograft valves for primary tissue failure [PTF]among the patients who had initial valve replacement at Seoul national University Hospital. The explanted valves were 69 porcine aortic [51 Hancock, 12 Angell-Shiley and 6 Carentier-Edwards] and 141 bovine pericardial [129 standard-profile and 12 low-profile ionescu-Shiley] valwes, with an overall incidence of PTF of 15.2%. The operative mortality rate of re-replacement was 5.1%. Calcific degeneration and tissue damage in relation to calcification were the most frequent modes of PTF on gross examinatin of the explanted valves resulting hemodynamically in valvular regurgitation. The number of Hancocg porcine and the standard-profile Ionescu-Shiley valves in valves in mitral position failed more often from tissue damage [tears, holes, and loss or destruction of cuspal tissue] than calcification [68.3% vs. 39.0%, p<0.01] with resultant regurgitation in 61%, the Ionescu-Shiley valves in the same position in 53%. The tendency of more calcification than tissue damage[71.3% vs. 33.3%, p<0.001]with stenosis in 53%. The tendency of more calcification and immobility of cusps in the latter group was partly explainable by the inclusion of patients of pediatric age. Observation made in this study suggest : many of bioprosthetic valves would fail from calcification and tissue damage : some fail prematurely because of mechanical stress probably owing to the valve design in construction ; andeven those valves escaped early damage would be subject to calcify in the prolonged follow-up period. In conclusion, at the present time, the clinical use of bioprostheticxenograft valves seems to be quite limited until further improvement in biocompatibility and refinement in valve design in manufacture are achieved.

• Research in Community and Public Health Nursing
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• v.7 no.2
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• pp.400-409
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• 1996

To investigate industrial fatigue and low back pain, the questionaire survey for subjective symptoms of fatigue and low back pain was carried out among 591 male workers aged 20-55 employed in an automobile industry in Korea. Workers participated to this study were divided into low back pain group(LBP) and control group, according to the self-reports by written questionaires. The subjective sysptoms of fatigue comprised three groups of 10 items each, representing dullness and sleepiness(level of cerebral activation), difficulty in concentration(level of motivation) and bodily projection of fatigue. The resultant data were processed for $\chi^2-test$, t-test and a pearson's correlation coefficient to confirm the relationships. The results were as follows: 1. 30 items of fatigue subjective symptoms exeptone item, 'lack in perseverance', were directly associated with low back pain. 2. The percentage of fatigue complaint were sig nificantly higher in LBP group. 3. Of the 30 items of fatigue subjective symptoms, the highest percentage was accounted for 'eye strain'(27.9%), followed by 'whole body feels tired' and 'legs feel heavy'(22.9%), 'feel like lying'(21.4%), 'feel a pain in the low back'(18.7%), 'feel drowsy'(16.4%) and 'feel stiffness in the neck or the shoulders'(16.2%) in the order of sequence. 4. The average weighted score for the first group of fatigue items(dullness and sleepiness) was the largest among three groups and was followed by the second group(difficulty in concentration) and the third group(bodily projection of fatigue) in the order of sequence, suggesting the heavier shift work stress of the workers. 5. In the groups of the aged 30-40, work duration of 5-7yrs, heavy work amount and irregular work speed, significant high fatigue complaints were revealed in terms of eye strain, whole body feels tired, legs feel heavy, feel like lying, feel a pain in the low back and feel stiffness in the neck or the shoulders. 6. A significant negative correlations were shown between age, work duration and eleven subjective symptoms while positive reciprocal correlations were shown between eleven items with one another.

• Tribology and Lubricants
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• v.22 no.4
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• pp.190-195
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• 2006

A simple and effective analysis method is presented for gaining a complete transient temperatures on the internal and external surfaces of a 40 mm gun tube subjected to a series of rapid firings. Two series of temperature data for both Hs and As were measured by using two rapid response k-type surface thermocouples near the firing origin and the muzzle. With other available temperature data, patterns of temperature variations of the gun tube as a function of time variable were driven through complete evaluations of the data. It is found that overall temperature gradients which increase exponentially toward saturation temperature, actually consist of a series of linear temperature gradients corresponding to the firing sequences. Under the similar firing sequences, patterns of temperature variations fur both the surface temperatures near the chamber and those near the muzzle were found to have linear temperature gradients with different values and the same response frequencies, i.e. they had peaks and lows in temperatures at the same time. The resultant complete temperature data can be used as the fundamental bases for analysis of thermoelastic properties of the materials such as thermal strain and stress, and f3r the prediction of cannon tube life-time through calculation of wear rate.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.10
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• pp.1433-1439
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• 2000

An experiment was carried out with 48 IVRI 2CQ rats 6-8 week old, weighing 50-100 g, to study the effect of lead exposure on antioxidant defense, lipid peroxide level, status of thiol groups and concentration of lead in the liver and kidneys at the end of the exposure and also after withdrawal of lead administration. Twenty four rats were given lead at a daily dose rate of 1 mg lead/2 ml of distilled water/kg body weight as lead acetate solution intraperitoneally for a period of 30 days. Another 24 control rats received 2 ml of sterile normal saline solution (0.85% NaCl)/kg body weight in an identical manner. A many-fold increase in concentration of lead was associated with a non-significant (p>0.05) decrease in the activities of superoxide dismutase (SOD) in the liver (27%) and kidneys (12%) and catalase in kidneys (22%). A significant (p<0.05) increase in lipid peroxide level was recorded in the liver (40%) compared with control values. There were significant (p<0.05) decreases in the total thiol and protein bound thiol contents in liver and an increase in non-protein bound thiol groups in the kidneys of lead exposed rats. During the 10 day observation period after withdrawal of lead administration, no significant change was observed with respect to any of the above parameters indicating that a 10 day withdrawal period was not enough for restoration of normality. It is concluded that the magnitude of response and the resultant changes in the lipid peroxide concentration, and the activities of SOD and catalase were not identical in the liver and kidneys of lead-exposed rats.

• Geotechnical Engineering
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• v.3 no.2
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• pp.55-70
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• 1987

An analytical solution procedure is described to estimate the developed passive lateral earth Pressures behind a vertical rigid retaintng wall rotating about its toe into a mass of cohesionless soil. Various stases of wall rotation, starting from an at-rest state to an initial Passive state to a full Passive state, are considered in the analysis. Condition of failure defined by a modified Mohr-coulomb criterion, together with equilibrium conditions, is used to obtain the necessary equations for the solution. Using methods of stress characteristics and numerical finite difference, a complete solution within and on the boundaries of the entire solution domain is made possible. The variations of the soil shear strength and the wall friction at various depths and stages of wall rotation are also taken into account in the analysis. The results predicted by the developed method of analysis are compared with those obtained from the experimental model tests on loose and dense sand. The comparisons show good agreements at various stages of retaining wall rotation Fin- ally, results of analytical parametric study are presented to demonstrate the effects of wall fric- tion on the resultant thrust and distribution of developed lateral earth pressures.

• Composites Research
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• v.13 no.6
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• pp.23-29
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• 2000

The internal residual stresses within the multilayered structure with sharp interface induced by the difference in thermal expansion coefficient between the materials of adjacent layers often provide the source of failure such as delamination of interfaces etc. Recent development of the multilayered structure with functionally graded interface would be the solution to prevent this kind of failure. However a systematic thermo-mechanical analysis is needed for the customized structural design of multilayered structure. In this study, theoretical model for the thermo-mechanical analysis is developed for multilayered structures of the $Al-SiC_p$ functionally graded composite for electronic packaging. The evolution of curvature and internal stresses in response to temperature variations is presented for the different combinations of geometry. The resultant analytical solutions are used for the optimal design of the multilayered structures with functionally graded interface as well as with sharp interface.

• Polymer(Korea)
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• v.39 no.2
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• pp.293-299
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• 2015

Conductive microcellular foams consisted of polystrene (PS) and polydopamine-coated carbon nanotube (PDA-CNT) were prepared via high internal phase emulsion (HIPE) polymerization and their morphology and electrical conductivity were investigated. CNT as a conductive nanofiller was modified to PDA-CNT by coating with hydrophilic PDA on the surface of CNT to increase aqueous phase dispersion and emulsion stability. It was possible to prepare the HIPEs having higher PDA-CNT content and the resultant foams having improved conductivity due to its good dispersion. The foams showed the morphology of interconnected cell structure. As PDA-CNT content increased, yield stress and storage modulus increased and cell size reduced. The PDA-CNT content showing electrical percolation threshold was ca. 0.58 wt% and the conductivity at PDA-CNT content of 5 wt% was increased to $10^{-3}S/m$.