• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.61-68
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• 1999

To analyze several defects and residual stress in sintering of layer structure materials, multiayer materials with TZP/SUS and ZT/SUS, and bilayer materials with porcelain/alumina and porcelain/Y-TZP were fabricated by sintering method. Multilayer materials prepared by pressureless sintering show the sintering defect such as warping, splitting, cracking originated from the difference of sintering shrinkage between each layer, which could be controlled by the adjustment of number and thickness in interlayer. In tape casting, a certain pressure given during sintering relaxed the sintering defects, specially warping. The residual stress in bilayer was examined with Vickers indentation method. A small tensile stress in porcelain/alumina and a large compressive stress in porcelain/Y-TZP were generated on the porcelain interface due to the thermal expansion mismatch, which affected the strength of bilayer materials. As a consequence, the sintering defects of multilayer materials and the residual stresses of bilayer materials were dominantly influenced on material design and starting material constants.

• Geomechanics and Engineering
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• v.22 no.5
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• pp.449-460
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• 2020

The double-lane arrangement model is frequently used in underground coal mines because it is beneficial to improve the mining efficiency of the working face. When the double-lane arrangement is used, the service time of the reserved roadway increases by twice, which causes several difficulties for the maintenance of the roadway. Given the severe non-uniform deformation of the reserved roadway in the Buertai Coal Mine, the stress distribution law in the mining area, the failure characteristics of roadway and the control effect of support resistance (SR) were systematically studied through on-site monitoring, FLAC 3D numerical simulation, mechanical model analysis. The research shows that the deformation and failure of the reserved roadway mainly manifested as asymmetrical roof sag and floor heave in the region behind the working face, and the roof dripping phenomenon occurred in the severe roof sag area. After the coal is mined out, the stress adjustment around goaf will happen to some extent. For example, the magnitude, direction, and confining pressure ratio of the principal stress at different positions will change. Under the influence of high-stress rotation, the plastic zone of the weak surrounding rock is expanded asymmetrically, which finally leads to the asymmetric failure of roadway. The existing roadway support has a limited effect on the control of the stress field and plastic zone, i.e., the anchor cable reinforcement cannot fully control the roadway deformation under given conditions. Based on obtained results, using roadway grouting and advanced hydraulic support during the secondary mining of the panel 22205 is proposed to ensure roadway safety. This study provides a reference for the stability control of roadway with similar geological conditions.

• Child Health Nursing Research
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• v.25 no.4
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• pp.377-387
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• 2019

Purpose: The purpose of this study was to examine the correlation between a flexible parental visiting environment and parental stress in neonatal intensive care units (NICUs). Methods: The study participants included 60 parents of premature infants in NICUs. Structured questionnaires and interviews, as well as observations by researchers using a caregiving behavior checklist, were used to measure the flexibility of the parental visiting environment and parents' stress levels. Quantitative and qualitative data were collected concurrently and were initially analyzed as separate data sets. Data collection extended from March 11, 2018 to June 30. 2018 and the data were analyzed using descriptive statistics, the independent t-test, one-way analysis of variance, and Pearson correlation coefficients. Results: There was a negative correlation (r=-.30, p=.021) between parental stress and the total number of visits in 7 days. We also found that the average duration of each visit and the number of caregiving behaviors performed by parents were positively correlated (r=.73, p<.001). Conclusion: When designing a flexible visiting environment for parents, parents should be encouraged to visit their babies. By doing so, stress can be reduced both for babies and for parents. Therefore, it is suggested that the related polices and regulations in South Korea should be changed to provide more a flexible visiting environment to promote better parent-child attachment and family adjustment.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.14-22
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• 2022

This study was conducted to promote male nursing students' adaptation to college life by identifying life stress, grit, and degree of adaptation to college life, and the effect of grit mediating effect on the relationship between life stress and college life adjustment. became The subjects of this study were 209 male nursing college students enrolled in nursing departments in 5 major cities. The collected data were analyzed with SPSS/WIN 25.0. Life stress showed a significant negative correlation with college life adaptation and grit, but grit showed a positive correlation with college life adaptation. As a result of mediating effect verification, the final model explained 43.5% of college life adaptation. Therefore, in order to improve male nursing students' adaptation to college life, it is required to develop a program that can lower life stress and increase grit and college life adaptation level.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.699-705
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• 2011

High-maneuver missile is a projectile which demands a strong momentum at short time. To produce a necessary thrust for the flight, the gas of high temperature and pressure is generated through explosive combustion of solid propellant, and a great thrust can be obtained by expanding this high temperature and pressure gas. Although the operating time of a rocket motor is less than a few seconds, a failure of part or ablation near the throat of nozzle may take place during the expansion of high temperature and pressure gas for great thrust. In other words, for the precise control of a missile an exact stress analysis considering both, the thermal stress caused by the heat transfer between combustion gas and wall, and the mechanical stress caused by the pressure change in the flow, should be considered first. In this connection, this study investigated the safety, as a point of view of stress and melting point of the material, of the pre-designed thrust generating structure which is subjected to high temperature and pressure as a function of motor operating time.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.3-12
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• 1999

The larger, loftier and more highly strengthened the recent structures become, the greater attention is paid to the problem of thermal crack occurrence associate with hydration heat. As one of methods to solve the problem, a care has been taken to the improvement of construction such as the application of pre-cooling or pipe-cooling, adjustment of concrete block size, concrete placement timing, joint arrangement and so on. But it is expected that a proper selection of cement shall additionally contribute to the control of thermal cracks. In this study, thus, we selected 4 types of cements such as Type V for anti-sulphate, blast furnace cements (slag content of 45% and 65% respectively)and ternary blended low heat cement, and carried out mock-up tests. In every assigned time, temperatures and thermal stresses were measured and calculated from raw data. As a result of measurement, it was found that the magnitude of hydration heat is in order of blast furnace slag cement. Type V and ternary blended low heat cement. Results of thermal stresses were same as the order of temperature. In addition, thermal stresses calculated from the data of strain gauges showed almost similar to those measured from effective stress gauges only when strain values were adjusted properly in accordance with initial time of stress appearance. Theoretical results agreed well with the measured values comparatively, but showed slight differences. It is inferred that these differences shall be reduced if more tests capable of evaluating thermal characteristics of concrete are carried out.

• The Journal of the Korea Contents Association
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• v.14 no.3
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• pp.301-313
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• 2014

This study aimed to identify the correlation of stress-coping, humor sense, and adaptation to college of nursing students. Three hundred thirty eight subjects completed a structured questionnaire in June 2012. Data were analyzed using SPSS/WIN 21.0 program. The mean scores were as follows; stress-coping 43.33, humor sense 72.18, and adaptation to college 68.02. It meant beyond the intermediate level. Significant differences were found between adaptation to college scores and general characteristics such as gender, academic year, family type, economic status, campus life satisfaction, relation with faculties, grade, and the relationship with the opposite gender. There was significant but weak correlation of stress-coping, humor sense, and adaptation to college. These results suggest that it is necessary to develop individualized education programs considering students' characteristics. Additionally, university adjustment related factors should be studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4917-4926
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• 2012

This study was designed to assess the factor of influence to occupational stress who work in the field of firefighters and questionnaire was uesd to analyse the stress scores and find the primary factors influence to occupational stress. The number of respondents were 408 who received the refresher training and period of investigation was august 2011 through october 2011. A structured questionnaire was employed to evaluate the participants' socio-demographics, job-related factors, health-related behaviors, occupational stress, reaction factor (fatigue, job satisfaction) and buffer factor (social support). Occupational stress and fatigue were assessed using the Korean Occupational Stress Scale-Short Form (KOSS-SF) and the Multidimensional Fatigue Scale (MFS), respectively. The analysis showed that we found a strong correlation between fatigue, job satisfaction and occupational stress. Occupational stress was associated with an increased risk of fatigue and decreased the job satisfaction. In the multiple regression analysis(stepwise), main factor that influence to occupational stress were job satisfaction, gender, age, processing number for a day, exercise. In logistic regression analyses, a higher occupational stress was associated with higher odds of fatigue(High) and the odds was down by 15.0% after adjustment for job satisfaction, gender, age, processing number for a day, exercise. Thus, a job satisfaction promote program for the reduction of occupational stress and the promotion of firefighters's health is strongly recommended.

• Korean Journal of Childcare and Education
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• v.9 no.2
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• pp.23-46
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• 2013

The purpose of this study was to obtain basic information for novice teachers' adjustment. The data from five novice teachers were collected by in-depth interviews of each subject, as well as reviewing a memo diary, journal and class diary. The results indicated that the novice teachers' experiences were categorized into difficulties in social relationships, heavy workload, stress related to making mistakes, obtaining support and assistance, adequate understanding of their field of work and so on. The model theory for their process of adjustment was found by grounded theory approach. The causal conditions include mistakes in performance of work and immaturity of managing social relationships. The contexts include age of the children, work conditions(i.e. time and space), amount of workload, unfamiliarity of new work assignments, personalities of colleagues, and high frequency of meeting parents of children. The intervening conditions are composed of a guidance program for novice teachers, support from colleagues, work rewards, and the personalities of novice teachers. The novice teacher use three strategies: trying to ignore, sharing difficulties and accessing support from friends or family, as well as willful efforts to transfer negative emotions into positive ones. The consequences of the strategies include: successful career progression, survival, and desire for leaving the field of work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.189-199
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• 2017

This study investigated the effects of life stress, cultural adaptation stress, and academic satisfaction amongst a total of 283 20's Chinese students majoring in cosmetology at colleges in Seoul. For this, data was collected from February to March 2017. The frequency analysis was conducted to verity the general characteristic of Chinese student studying in Korea who are study objects while utilizing SPSS Statistics V22.0 for data processing and analysis while the factor analysis and reliability analysis were conducted to investigate the validity of measurement tool and evaluate the reliability. Moreover, the regression analysis between variables and regression analysis were utilized. The results found the following: First, in terms of life stress, as peer relationship, appearance stress, economic stress, family relationship stress and academic stresses decreased, their academic satisfaction increased. Second, regarding cultural adaptation stress, as interpersonal and living culture stresses were lowered, academic satisfaction increased. Therefore, this study targets to derive implications on an efficient plan to improve the academic satisfaction of Chinese students studying in the Republic of Korea by developing and providing a proper academic program with a decent support system in terms of culture, life, and education after investigating their life and cultural adaptation stresses.