• BMB Reports
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• v.48 no.4
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• pp.209-216
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• 2015

Stress is now recognized as a universal premorbid factor associated with many risk factors of various chronic diseases. Acute stress may induce an individual's adaptive response to environmental demands. However, chronic, excessive stress causes cumulative negative impacts on health outcomes through "allostatic load". Thus, monitoring the quantified levels of long-term stress mediators would provide a timely opportunity for prevention or earlier intervention of stressrelated chronic illnesses. Although either acute or chronic stress could be quantified through measurement of changes in physiological parameters such as heart rate, blood pressure, and levels of various metabolic hormones, it is still elusive to interpret whether the changes in circulating levels of stress mediators such as cortisol can reflect the acute, chronic, or diurnal variations. Both serum and salivary cortisol levels reveal acute changes at a single point in time, but the overall long-term systemic cortisol exposure is difficult to evaluate due to circadian variations and its protein-binding capacity. Scalp hair has a fairy predictable growth rate of approximately 1 cm/month, and the most 1 cm segment approximates the last month's cortisol production as the mean value. The analysis of cortisol in hair is a highly promising technique for the retrospective assessment of chronic stress. [BMB Reports 2015; 48(4): 209-216]

• Journal of Korean Academic Society of Home Health Care Nursing
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• v.24 no.2
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• pp.169-180
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• 2017

Purpose: This study was conducted to investigate factors that affect job stress among caregivers in long-term care facilities. Methods: Data were collected from 125 caregivers through a structured questionnaire targeting general characteristics, violent experiences, coping, and job stress from February 2 to March 10, 2015. Data were analyzed by t-test, ANOVA, and multiple regression using SPSS 21.0. Results: The rate of violence experienced by caregivers was 99.2% for verbal abuse, 99.2% for physical violence, 95.2% for physical threatening, and 62.3% for sexual abuse. The mean score for coping and job stress was above average. Job stress significantly differed by marital status, education level, facility size, and policy on workplace violence. The significant predictors of job stress included policy on workplace violence, violent experiences, and education level. The regression model explained 28.0% of the variance in job stress. Conclusion: To improve job stress of caregivers, it is necessary to establish policies for violence within the organization and to develop and apply various programs that allow caregivers to work safe from violence both physically and psychologically.

• Structural Engineering and Mechanics
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• v.20 no.2
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• pp.173-189
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• 2005

The paper presents a finite element model for studying timber-concrete composite beams under long-term loading. Both deformability of connection system and rheological behaviour of concrete, timber and connection are fully considered. The creep of component materials and the influence of moisture content on the creep of timber and connection, the so-called "mechano-sorptive" effect, are evaluated by means of accurate linear models. The solution is obtained by applying an effective step-by-step procedure in time, which does not require storing the whole stress history in some points in order to account for the creep behaviour. Hence the proposed method is suitable for analyses of composite beams subjected to complex loading and thermo-hygrometric histories. The possibility to accurately predict the long-term response is then shown by comparing numerical and experimental results for different tests.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.320-320
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• 2010

The dye-sensitized solar cells (DSSCs) have achieved so far the highest validated efficiency over 11%. However, the cells with the best performance utilize volatile solvent as a electrolyte, which can cause some practical limitations for the long-term operation. This is one of the most substantial problems to be resolved for the commercialization of DSSCs. In order to improve the long-term stability, many research groups have reported new electrolyte system, to replace the liquid type electrolyte by non-volatile ones. In this work, we studied long-term stability of the DSSCs with various types of electrolytes such as (PVDF HFP) based polymer, eutectic melts of ionic liquids, and liquid based solvent. The cells with various electrolytes have been exposed to the condition under thermal stress and illumination over 1000 hours. We will report the change of photovoltaic properties with time and investigate the degradation mechanism with the impedance spectroscopic analysis.

• Geomechanics and Engineering
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• v.29 no.2
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• pp.171-182
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• 2022

Reusing the used pile has not yet been implemented due to the unpredictability of the bearing capacity evolution. This paper presents an analytic approach to estimate the sides shear setup after the dissipation of pore pressure. Long-term evolution of adjacent soil is simulated by viscoelastic-plastic constitutive model. Then, an innovative concept of quasi-overconsolidation is proposed to estimate the strength changes of surrounding soil. Total stress method (α method) is employed to evaluate the long term bearing capacity. Measured data of test piles in Louisiana and semi-logarithmic time function are cited to validate the effectiveness of the presented method. Comparisons illustrate that the presented approach gives a reasonably prediction of the side shear setup. Both the presented method and experiment show the shaft resistance increase by 30%-50%, and this highlight the potential benefit of piles reutilization.

• Geomechanics and Engineering
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• v.36 no.1
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• pp.83-97
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• 2024

It is important to make reasonable prediction about the long-term deformation of high rockfill geostructures. However, the deformation is usually underestimated using the rockfill parameters obtained from laboratory tests due to different size effects, which make it necessary to identify parameters from in-situ monitoring data. This paper proposes a novel hybrid back-analysis method with a modified objective function defined for the time-dependent back-analysis problem. The method consists of two stages. In the first stage, an improved weighted average method is proposed to quickly narrow the search region; while in the second stage, an adaptive response surface method is proposed to iteratively search for the satisfactory solution, with a technique that can adaptively consider the translation, contraction or expansion of the exploration region. The accuracy and computational efficiency of the proposed hybrid back-analysis method is demonstrated by back-analyzing the long-term deformation of two high embankments constructed for airport runways, with the rockfills being modeled by a rheological model considering the influence of stress states on the creep behavior.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.104-112
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• 2014

Generally, numerical approaches of evaluation for vehicle seat comfort have been studied without considering time-dependent characteristics and the only seating moment have been considered in seat design. However, the comfort not only at the seating moment but also in the long-term should be evaluated because the passengers are sitting repeatedly on the seat to drive the vehicle for hours. So, the aim of this paper is to carry out a quantitative evaluation of the time-dependent mechanical characteristics of seat foams and to suggest a process for predicting the viscoelastic deformation of seat foam in response to long-term driving. To characterize the seat materials, uniaxial compression and tension tests were carried out for the seat foam and stress relaxation tests were performed for evaluating the viscoelastic behavior of the seat foam. A unit solid element model was used to verify the reliability of the material model with respect to the compression behavior of the seat foam. It is not straightforward to evaluate the time-dependent compression of foams using the explicit solver because the viscoelastic material model is limited. To use the explicit solver, the material model must be modified using stress-degradation data. Normalized stress relaxation moduli were added to the stress-strain curves obtained under static conditions to achieve a time-dependent set of stress-strain relations that were compatible with the implicit solver. There was good agreement between the analysis results and experimental data.

• Journal of Korean Academy of Nursing Administration
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• v.12 no.3
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• pp.343-354
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• 2006

Purpose: The purpose of this study was to analyze the prevalence and consequences of verbal abuse in the operating room nurses by physicians and other nurses. Method: The data were collected from 761 operating nurses. The period of data collection was from September 7 to November 25, 2004. For this study the following tools were used: the verbal abuse scale, the emotional stress scale and the long-term negative effect scale. The data were analyzed by using SPSS Win 11.5. Result: 744 nurses reported experiencing some type of verbal abuse from a physician and other nurses. The emotional stress and long-term negative effect were significantly increased by verbal abuse. The nurses of less than one year increased emotional stress from verbal abuse. The physician was the most frequent source of emotional stress by verbal abuse, followed by other nurses. The long-term negative effect was significantly increased in the factors of emotional stress and the physician was the most frequent source than other nurses. Conclusion: Verbal abuse of nurses by physicians and other nurses continues to exist and is associated with negative consequences. Nurse administrators have to assess the present state for workplace verbal abuse and must endeavor in order to reduce verbal abuse.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.273-283
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• 2021

The purpose of this study is to identify factors affecting the stress of End-of-life care in long-term care hospitals and to identify perception and education requirement of End-of-life care. The subjects of this study were 163 nurses who had worked at seven long-term care hospitals in Gyeongsangnam-do for more than six months and had more than one end-of-life care experience. They agreed to participate in the study using structured questionnaires from May 27 to June 7, 2021. As a result of this study, the most influential factor for the terminal care stress of the nurses in the long-term care hospitals is the education needs of End-of-life care(β=.25, p=.001). The following factors have been identified death anxiety (β=.21, p=.005), satisfaction with the End-of-life care environment (β=.17, p=.017), and End-of-life care perception(β=-.15, p=.040). Based on the results of this study, it is necessary to meet the educational needs of the End-of-life care for the nurses in the long-term care hospitals in order to relieve their stress. For this, it is necessary to develop and apply educational programs for End-of-life care.

• Journal of Korean society of Dental Hygiene
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• v.2 no.2
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• pp.145-158
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• 2002

This is a section study for research of main cause and coping ways caused by stresses during the clinical experiment. It was researched by 231 students of third grade have finished clinical experiment until September though questionnaire. The methods for this study used the a stress measuring instrument thai was used by Hoa-Yun Jun and coping ways of stresses devised by Bell. We computed the frequency and the mean value by the SPSS 10.0 statistical data and we got the following result that from the experiment with t-test and the ANOVA analysis. 1. The mean value of stresses indicated rather higher states in figures 2,855 and the figures that were classified by each areas, indicated highest figures are affected by circumstances, that is 3.065. 2. As higher as the degree of satisfactions in their major, students feel stress less so, the result was not quite different between each of them (p=0.007). 3. The copping ways of stresses indicated, similar differences by using of long-term copping ways and short-term copping ways to cope with stresses(p=0.000). 4. In case of the students who failed college entrance exams and prepared for the next chance for more than one year, indicated highest figures that is 2.57 in short-term ways to cope with stresses, so it showed slightly differences between them(p=0.014). 5. According to the satisfactions of clinical experiments, there were not any statistical differences in long-term coping ways but, as smaller as the satisfactions, in that evidence of the students use short-term copping ways, it showed slightly differences between them(p=0.041). 6. According to the degree of stresses, low-stress groups use short-term coping ways more than high-stress groups, so it showed slightly differences between them(p=0.001). 7. As far as the using of long-term coping ways, the figures of between the lower stress groups and the higher stress groups indicated 2.89 and 2.97 respectably so, the figures were not so closed.