• Korean Journal of Childcare and Education
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• v.13 no.4
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• pp.19-35
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• 2017

Objective: This study aimed to investigate the mediating effect of stress-coping strategies of childcare teachers' creative personality on teacher efficacy. Methods: Study subjects were 204 childcare teachers working at nursery schools located in S city of Gyeonggi province, and this study collected materials from childcare teachers through a self-report survey. For materials collected, this study conducted frequency analysis, correlation analysis and multiple regression analysis using spss 21.0, and verified the mediating effect through the Sobel Test. Results of this study are as follows. Results: First, there was a positive correlation among creative personality, teacher efficacy and stress-coping strategies. Second, results show that stress-coping strategies mediate the effect of childcare teachers' creative personality on teacher efficacy. Lastly, problem-focused coping strategies turned out to be full mediation, whereas coping strategies seeking social support was partial mediation. Conclusion: Based on the results, this study suggested the necessity to prepare a practical plan for enabling childcare teachers to use stress-coping strategies in a successful way.

• Carbon letters
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• v.26
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• pp.74-80
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• 2018

The South Korean Ministry of the Environment has revised the laws relating to the management of interior air quality for multiple use facilities, and recommends maintaining carbon dioxide ($CO_2$) concentration in passenger vehicles below 1000 ppm during operation in urban areas of large cities. However, the interior $CO_2$ concentration of passenger vehicles can rapidly increase and exceed 5000 ppm within 30 min, as observed when two passengers are traveling in urban areas of the South Korean city of Jeonju with the air conditioner blower turned off and the actuator mode set to internal circulation mode. With four passengers, $CO_2$ concentration can reach up to 6000 ppm within 10 min. To counter this, when the actuator is set to external mode, $CO_2$ concentration can be maintained below 1000 ppm, even after a long period of running time. As part of the air conditioning system, alkali-treated activated carbon fiber filters are considered to be far superior to the commercial non-woven filters or combination filters currently commonly in use.

• Composites Research
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• v.13 no.3
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• pp.48-57
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• 2000

Fracture analysis of coating cracking on a substrate system described in a companion paper was applied and verified by four-point bending tests. The multiple cracking of coating was predicted using a fracture mechanics approach. The strain energy release rate (G) due to the formation of a new crack in a coating was obtained. A crack density vs. strain data of metallic and polymeric substrate was used to get the in-situ fracture toughness of coating with respect to various baking time and temperature. The $G_c$ was decreased as the baking temperature and time was increased. This paper gave insight about usefulness of four-point bending test for fracture toughness evaluation of coating and it gave a new method for in-situ coating toughness.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.347-355
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• 2013

A damage estimation method for monopile support structure of offshore wind turbine using modal properties and committee of neural networks is presented for effective structural health monitoring. An analytical model for a monopile support structure is established, and the natural frequencies, mode shapes, and mode shape slopes for the support structure are calculated considering soil condition and added mass. The input to the neural networks consists of the modal properties and the output is composed of the stiffness indices of the support structure. Multiple neural networks are constructed and each individual network is trained independently with different initial synaptic weights. Then, the estimated stiffness indices from different neural networks are averaged. Ten damage cases are estimated using the proposed method, and the identified damage locations and severities agree reasonably well with the exact values. The accuracy of the estimation can be improved by applying the committee of neural networks which is a statistical approach averaging the damage indices in the functional space.

• Journal of Home Health Care Nursing
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• v.9 no.2
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• pp.129-137
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• 2002

Purpose: This study was aimed to investigate predictors of job satisfaction of home visiting nurses at the 16 public health centers in Busan. Method: There are two groups of independent factors: non-work related (age. educational level. working duration as nurses in hospitals. certificate). and work related (working duration as nurses in public health centers. working duration as home visiting nurse. position. number of households visited per week, workload, cooperation among staff, support by supervisors, supply of vehicles, supply of materials). The participants were 88 home visiting nurses from 16 public health centers in Busan. Data were collected with self-administrated questionnaires and analysed using an univariate logistic regression and multiple logistic regression analysis. Result: support by supervisors (good vs not-good, OR=3.70. p=0.025), and supply of materials (good vs not-good, OR=3.33, p=0.038) had significants effects on job satisfaction. Conclusion: The results were similar to those of other studies on the predictors of job satisfaction of clinical nurse at hospitals, and were helpful in developing nursing interventions to increase job satisfaction among home visiting nurses in public health centers. Busan.

• The Korean Journal of Health Service Management
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• v.4 no.1
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• pp.23-41
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• 2010

The purpose of this study was to provide basic materials needed to enhance quality of organizational life by identifying the improvements of labor union management in the perspective of hospital organization management. Materials were collected from administrators, nurses and medical technicians in target hospitals from March 3 to March 3 to March 30, 2010 through survey questionnaires. The main results of this study were as follows: 1. The commitment level of the subjects according to their satisfaction was higher when the administrators both in Private hospitals and Public hospitals were not satisfied in their works. 2. The commitment level of the subjects according to the subjects' job dedication level was higher those who had higher emotional attachment to their job in all vocations in both Private hospitals and Public hospitals. 3. The commitment level of the subjects according to the subjects' labor union involvement was higher in those who had higher satisfaction in labor union and perceived their colleagues' attitudes more positively in all vocations in both Private Hospitals and Public Hospitals. 4. From the results of multiple regression analysis to identify major influencing factors of labor union commitment level, In Private hospital employees, those who had senior officer posts in labor union and higher normative commitment showed higher commitment union. Therefore hospital managers should have democratic and flexible attitudes toward labor union. Additionally, as colleagues attitudes is important determinant in union commitment, hospital managers should have countermeasures to enhance the work atmosphere of hospital employees.

• Structural Engineering and Mechanics
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• v.45 no.4
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• pp.471-494
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• 2013

In this paper, identification of isotropic and orthotropic linear elastic material constitutive parameters has been demonstrated by a FEA-free energy-based inverse analysis method. An important feature of the proposed method is that it requires no finite element (FE) simulation of the tested material. Full-field displacements calculated using digital image correlation (DIC) are used to compute DIC stress fields enforcing the equilibrium condition and DIC strain fields using interpolation functions. Boundary tractions and displacements are implicitly recast into an objective function that measures the energy residual of external work and internal elastic strain energy. The energy conservation principle states that the residual should be zero, and so minimizing this objective function inversely identifies the constitutive parameters. Synthetic data from simulated testing of isotropic materials and orthotropic composite materials under 2D plane stress conditions are used for verification of the proposed method. When identifying the constitutive parameters, it is beneficial to apply loadings in multiple directions, and in ways that create non-uniform stress distributions. The sensitivity of the parameter identification method to noise in both the measured full-field DIC displacements and loadings has been investigated.

• Computers and Concrete
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• v.26 no.3
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• pp.257-273
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• 2020

Concrete bond strength with steel re-bars depends on multiple factors including concrete-steel interface and mechanical properties of concrete. However, the hydration development of cementitious paste, and in turn the mechanical properties of concrete, are negatively affected by cold weather. This study aimed at exploring the concrete-steel bonding behavior in concrete cast and cured under freezing temperatures. Three concrete mixtures were cast and cured at -10 and -20℃. The mixtures were protected using conventional insulation blankets and a hybrid system consisting of insulation blankets and phase change materials. The mixtures comprised General Use cement, fly ash (20%), nano-silica (6%) and calcium nitrate-nitrite as a cold weather admixture system. The mixtures were tested in terms of internal temperature, compressive, tensile strengths, and modulus of elasticity. In addition, the bond strength between concrete and steel re-bars were evaluated by a pull-out test, while the quality of the interface between concrete and steel was assessed by thermal and microscopy studies. In addition, the internal heat evolution and force-slip relationship were modeled based on energy conservation and stress-strain relationships, respectively using three-dimensional (3D) finite-element software. The results showed the reliability of the proposed models to accurately predict concrete heat evolution as well as bond strength relative to experimental data. The hybrid protection system and nano-modified concrete mixtures produced good quality concrete-steel interface with adequate bond strength, without need for heating operations before casting and during curing under freezing temperatures down to -20℃.

• Computers and Concrete
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• v.5 no.6
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• pp.573-597
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• 2008

Among artificial intelligence-based computational techniques, adaptive neuro-fuzzy inference systems (ANFIS) are particularly suitable for modelling complex systems with known input-output data sets. Such systems can be efficient in modelling non-linear, complex and ambiguous behaviour of cement-based materials undergoing single, dual or multiple damage factors of different forms (chemical, physical and structural). Due to the well-known complexity of sulfate attack on cement-based materials, the current work investigates the use of ANFIS to model the behaviour of a wide range of self-consolidating concrete (SCC) mixture designs under various high-concentration sodium sulfate exposure regimes including full immersion, wetting-drying, partial immersion, freezing-thawing, and cyclic cold-hot conditions with or without sustained flexural loading. Three ANFIS models have been developed to predict the expansion, reduction in elastic dynamic modulus, and starting time of failure of the tested SCC specimens under the various high-concentration sodium sulfate exposure regimes. A fuzzy inference system was also developed to predict the level of aggression of environmental conditions associated with very severe sodium sulfate attack based on temperature, relative humidity and degree of wetting-drying. The results show that predictions of the ANFIS and fuzzy inference systems were rational and accurate, with errors not exceeding 5%. Sensitivity analyses showed that the trends of results given by the models had good agreement with actual experimental results and with thermal, mineralogical and micro-analytical studies.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.20.2-20.2
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• 2011

III-nitrides have attracted much attention for optoelectronic device applications whose emission wavelengths ranging from green to ultraviolet due to their wide band gap. However, due to the strong polarization properties of conventional c-plane III-nitrides, the built-in polarization-induced electric field limits the performance of optical devices. Therefore, there has been a renewed interest in the growth of nonpolar III-nitride semiconductors for polarization free heterostructure optoelectronic and electronic devices. However, the crystal and the optical quality of nonpolar/semipolar GaN have been poorer than those of conventional c-plane GaN, resulting in the relative poor optical and electrical properties of light emitting diodes (LEDs). In this presentation, I will discuss the growth and characterization of high quality nonpolar a-plane and semipolar (11-22) GaN and InGaN multiple quantum wells (MQWs) grown on r- and m-plane sapphire substrates, respectively, by using metalorganic chemical vapor deposition (MOCVD) without a low temperature GaN buffer layer. Especially, the epitaxial lateral overgrowth (ELO) technique will be also discussed to reduce the dislocation density and enhance the performance of nonpolar and semipolar GaN-based LEDs.