• Polymer(Korea)
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• v.29 no.2
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• pp.198-203
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• 2005

Melt extrusion foaming process for the preparation of poly(L-lactic acid) (PLLA) scaffolds was carried out and the effects of foaming conditions on the pore structure of PLLA scaffolds and their mechanical properties were investigated. The porosity and mechanical properties of fabricated scaffolds were compared with the scaffolds obtained from the salt leaching method as well. It was found that the optimum pore structure was achieved when the PLLA melt was kept in extruder for the maximum decomposition time of blowing agent. In order to maintain the proper scaffolds structure, the blowing agent content should be less than $10\;wt\%$. It can be concluded that melt extrusion foaming process allows for the production of scaffold having higher mechanical properties with reasonable pore size and open cell structure for hard tissue regeneration even though it has less porosity than scaffolds made by salt leaching process.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.524-529
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• 2020

To increase the mechanical durability of the proton exchange membrane fuel cells, a reinforced membrane in which a support is placed in the polymer membrane is used. The support mainly uses e-PTFE, which is hydrophobic and does not transfer ions, which may cause performance degradation. In this study, we investigated the effect of e-PTFE support on PEMFC performance and electrochemical durability. In this study, the reinforced membrane with the support was compared with the single membrane (non-reinforced membrane). Due to the hydrophobicity of the support, the water diffusion coefficient of the reinforced membrane was lower than that of the single membrane. The reinforced membrane had a lower water diffusion coefficient, resulting in higher HFR, which is the membrane migration resistance of ions, than that of a single membrane. Due to the low hydrogen permeability of the support, the OCV of the reinforced membrane was higher than that of the single membrane. The support was shown to reduce the hydrogen permeability, thereby reducing the rate of radical generation, thereby improving the electrochemical durability of the reinforced membrane.

• Child Health Nursing Research
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• v.20 no.4
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• pp.350-358
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• 2014

Purpose: The purpose of this study was to define and clarify the concept of developmental care for preterm infants. Methods: The hybrid model method was used to identify the main attributes and indicators. In the field work stage, data were collected in Seoul and Cheonan, Korea. The participants were 5 nurses working in the NICU. Results: The concept of developmental care was found to have six attributes and ten indicators in 2 dimensions. For the nursing practice dimension, four attributes were derived. They were being like intrauterine state, individualization, interaction, and integrative care with awareness of development. For the family centeredness dimension, supporting parental attachment and professional alliance were attributes of developmental care. Conclusion: Developmental focused care can facilitate the identification of behavioral responses of newborns and provide individualized interventions for fostering growth and development. This concept analysis could provide guidelines for "developmental care" nursing practice and be useful for research in the neonatal field.

• Journal of Digital Convergence
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• v.15 no.9
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• pp.375-384
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• 2017

The Purpose of this study was to examine, the effects of depression, family Support, and medical suport on rehabilitation motivation among stroke patients. Participants in this cross- sectional, descriptive study were 206 stroke patients who completed a self-report structured questionnaire. The data were analyzed using descriptive statistics, t-test, one-way ANOVA, correlation and stepwise multiple regression analyses with IBM SPSS Win 22 Program. Family support, medical support, education and age were strong predictors of rehabilitation motivation in stroke patients. These variables explained 58.3% of the variance in rehabilitation motivation. Depression was not a predictor of rehabilitation motivation. A higher level of rehabilitation motivation was associated with lower levels of depression and higher levels of family support and medical support. These results show that effective strategies for improving family support and medical support. are needed to improving rehabilitation motivation among stroke patients.

• Nuclear Engineering and Technology
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• v.28 no.1
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• pp.17-26
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• 1996

The in-reactor fuel rod support conditions against the fretting wear-induced damage can be evaluated by residual spacer grid spring deflection or rod-to-grid gap. In order to evaluate the impact of fuel design parameters on the fretting wear-induced damage, a simulation methodology of the in-reactor fuel rod supporting conditions as a function of burnup has been developed and implemented in the GRIDFORCE program. The simulation methodology takes into account cladding creep rate, initial spring deflection, initial spring force, and spring force relaxation rate as the key fuel design parameters affecting the in-reactor fuel rod supporting conditions. Based on the parametric studies on these key parameters, it is found that the initial spring deflection, the spring force relaxation rate and cladding creepdown rate are in the order of the impact on the in-reactor fuel rod supporting conditions. Application of this simulation methodology to the fretting wear-induced failure experienced in a commercial plant indicates that this methodology can be utilized as an effective tool in evaluating the capability of newly developed cladding materials and/or new spacer grid designs against the fretting wear-induced damage.

• Nuclear Engineering and Technology
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• v.28 no.1
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• pp.56-71
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• 1996

The local hydrulic characteristics in subchannels of 5$\times$5 nuclear fuel bundles with spacer grids were measured at upstream and downstream of the spacer grid for the investigation of the spacer grid effects on turbulent flow structure by using an LDV(Laser Doppler Velocimeter). The measured parameters are axial velocity and turbulent intensity, skewness factor, and flatness factor. Pressure drops were also measured to evaluate the loss coefficient for the spacer grid and the friction factor for rod bundles. From these data, it was found that the turbulent mixing and forced mixing occur up to $x/D^h=10$ and 20 from the spacer grid, respectively. The turbulence decay behind spacer grid behaves in the similar decay rate as turbulent flow through mesh grids or screens. Mixing factors useful in subchannel analysis code were correlated from the data and show the highest value near spacer grid and then have a stable values.

• Journal of Digital Convergence
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• v.18 no.9
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• pp.403-411
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• 2020

The purpose of the study is to investigate the impact of social support and mental health of health science college students on their resilience. 191 students enrolled in 3 health science colleges located in J Province were asked to answer structured questionaries, and the collected data was analyzed by T-test, ANOVA, Pearson correlation, and regression analysis with SPSS 24.0 software. The result of this study shows that social support has positive correlation to resilience, whereas mental health has statistically significant negative correlation to psychological resilience. Subfactor of social support that affect psychological resilience are material and repetitional support, and subfactor of mental health are anxiety and college life satisfaction, which is also a sociologic characteristic, with explanatory power of 48.9%. The study suggests the need to develop and apply measures to improve social support and mental health of health science college students to embolden their resilience.

• Proceedings of the KHMA Conference
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• 2013.11a
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• pp.203-203
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• 2013

• The Korean Journal of Applied Statistics
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• v.26 no.1
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• pp.131-139
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• 2013

Support vector machines(SVM) may perform poorly in the presence of noise variables; in addition, it is difficult to identify the importance of each variable in the resulting classifier. A feature selection can improve the interpretability and the accuracy of SVM. Most existing studies concern feature selection in the linear SVM through penalty functions yielding sparse solutions. Note that one usually adopts nonlinear kernels for the accuracy of classification in practice. Hence feature selection is still desirable for nonlinear SVMs. In this paper, we compare the performances of nonlinear feature selection methods such as component selection and smoothing operator(COSSO) and kernel iterative feature extraction(KNIFE) on simulated and real data sets.

• Land and Housing Review
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• v.6 no.3
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• pp.139-145
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• 2015

To improve the pile design efficiency(design bearing capacity/the strength of materials) from 70 percent(160tonf) to 80 percent(190tonf), this paper analysed the existing pile loading test data and performed the precise dynamic loading test and Bi-directional loading test for the first time in Korea. Analysis result of the existing dynamic loading test data by Davisson method showed that bearing capacity of piles penetrated at weathered rock stratum(N=50/15) exceeded 190tonf. But the analysis result by CAPWAP method showed that piles less than the target bearing capacity were 40% due to the lack of impact energy. To get the target bearing capacity from the dynamic loading test, using the hammer over 6tonf to trigger the enough impact energy is necessary. Allowable bearing capacty of Bi-directional static loading test by Davisson method was 260.0~335tonf(ave. 285.3tonf) and exceeded overwhelmingly the target capacity. And this exceeded the bearing capacity of precise dynamic loading test(ave. 202.3tonf) performed on the same piles over 40%. The difference between the capacity of Bi-directional loading test and dynamic loading test was caused by the insufficient impact energy during dynamic loading test and increase by interlocking effect by near piles during Bi-directional static loading test.