• Journal of Technologic Dentistry
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• v.43 no.1
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• pp.6-12
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• 2021

Purpose: This study aimed to compare the shear bond strength between zirconia cores and veneer ceramics as per the sand blasting and liner treatments. Methods: The following 4 groups of zirconia-veneering ceramic specimens were prepared: (1) Group I, untreated; (2) Group II, with 110 ㎛ aluminium oxide (Al2O3) sandblasting; (3) Group III, with liner (IPS e.max ZirLiner; Ivoclar Vivadent); and (4) Group IV, with 110 ㎛ Al2O3 sand blasting and liner. Surface roughness was measured for all the prepared specimens, and the surface morphology was observed using a scanning electron microscope. All the samples (n=40) were fixed with measuring jigs, and shear bond strengths were obtained using a universal testing machine with a crosshead speed of 0.5 mm/min. The shear bond strength data were analyzed using one-way analysis of variance and t-test. The post hoc comparison was performed using the Tukey's test (α=0.05). Results: A significant difference in the surface roughness was observed between the specimens of groups I and II (p<0.05). Surface treatment with liner and sandblasting showed higher shear bond strength between zirconia core and veneering ceramic (p<0.05). Conclusion: The sand blasting and liner treatment increased the shear bond strength between zirconia core and veneering ceramic.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.404-409
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• 2017

Natural polymer chitosan has been widely applied to medical fields due to its biochemical activities such as anticancer, antibacterial and lowering cholesterol in addition to biocompatibility and biodegradability. Currently, researches are being actively conducted to develop various drug-encapsulated chitosan nanoparticles for curing different diseases by applying chitosan to a drug delivery system. The free amine ($-NH_2$) group present in chitosan can bind to various hydrophobic groups by physical and chemical modification and the chitosan with hydrophobic groups can form shell-core nanoparticles by self-assembly when dispersed in water. In addition, an insoluble drug can increase the solubility against water when it was encapsulated in the core of chitosan nanoparticles. Also, the therapy effect can be maximized by minimizing side effects of drugs such as proteins, anticancer drugs and vaccines when they were encapsulated in the core of chitosan nanoparticles. Moreover, it is possible to control the particle size and release rate according to the hydrophobic group introduced to chitosan, so that it can be applied to a wide range of medical fields. The purpose of this review is to discuss the preparation and property of chitosan nanoparticles modified with various hydrophobic groups, and the application to drug delivery systems according to their property.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.441-448
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• 2016

The purpose of this study was to identify the effects of mentoring senior core fundamental nursing skills education on clinical competence and critical thinking disposition in nursing students. The research design was a one group pre-posttest design and the participants were 57 nursing students. The contents consisted of 3 core fundamental nursing skills of vital sign, nelaton catheterization and subcutaneous injection and total duration of 6 hours. Mentoring seniors conducted to rapport forming & education and evaluated them after exercise and evaluation under the guidance of professor. Data were collected using self-administered questionnaires in pre-test and post-test, the collected data were analyzed using paired t-tests. The result shows the scores of clinical competence and critical thinking disposition were increased significantly after mentoring senior core fundamental nursing skills education in nursing students. The results indicate that this study was effective in improving nursing students clinical competence and critical thinking disposition in core fundamental nursing skills and is expected to be utilized in nusing practice education. Additional studies including those on control groups are recommended to compare difference between the experimental group and control group.

• Journal of the Korea Society of Computer and Information
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• v.27 no.6
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• pp.157-165
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• 2022

The purpose of this study was to determine whether unstable surface core exercise is more effective than stable surface core exercise on improving functional movement and balance and reducing pain in sedentary female workers with backpain. Participants were randomly assigned to an unstable surface core exercise(UEG; n=10) or a stable surface core exercise(SEG; n=10) group. They participated in the given exercise for 8 weeks. FMS, Y-Balance and VAS were measured before and after the participation in exercise, which were subjected to a repeated-measures ANOVA. In the case of a significant interaction between time and group, paired sample t-tests were conducted for a post hoc analysis within each subject group. Results indicated that FMS of the UEG had a significant effect on HS (p<.01), ASLR (p<.05) and TS(p<.001), but not for other variables. YBT did not show a significant effect for any variable (AT, PL, PM, TS), although the main effect of time was significant in both subject groups. VAS had a significant effect only in the UEG(p<.001). Our findings indicate that compared to SEG, UEG is more effective for improving functional movement and reducing pain, but not for improving balance, in sedentary female workers with backpain.

• Journal of the Korean Chemical Society
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• v.67 no.4
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• pp.271-280
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• 2023

The purpose of this study is to investigate the effect of chemistry program based on metacognitive learning strategies using realistic contents on prospective teachers' creative thinking skills and science core competencies, and their perception. In particular, it was intended to further improve the effectiveness of the program by introducing a strategy to strengthen metacognition. Participants were classified into the experimental group subject to the newly developed chemistry curriculum and traditional group subject to general programs that exclude realistic contents and metacognitive strategies. Both groups were surveyed before and after the application of the program to measure the degree of change in metacognitive competencies, creative thinking competencies, and science core competencies. It also analyzed the impact of metacognitive competencies and science core competencies on creativity thinking competencies. As a result of the study, relevance and rationality among sub-factors of metacognitive competencies and creative thinking competencies of the experimental group were improved, and all sub-factors except for scientific participation and lifelong learning ability among science core competencies were significantly improved. In addition, it was found that metacognitive knowledge among metacognitive competencies, scientific inquiry ability and scientific thinking ability among science core competencies affect creative thinking competencies. Through the results, it was suggested that realistic content that incorporates metacognitive learning strategies is needed to improve creative thinking competencies, and learning models and programs that can utilize them are needed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.2979-2995
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• 2017

In recent years, there has been an increasing number of studies focused on identifying a set of spreaders to maximize the influence of spreading in complex networks. Although the k-core decomposition can effectively identify the single most influential spreader, selecting a group of nodes that has the largest k-core value as the seeds cannot increase the performance of the influence maximization because the propagation sphere of this group of nodes is overlapped. To overcome this limitation, we propose a neighborhood coreness cover and discount heuristic algorithm named "NCCDH" to identify a set of influential and decentralized seeds. Using this method, a node in the high-order shell with the largest neighborhood coreness and an uncovered status will be selected as the seed in each turn. In addition, the neighbors within the same shell layer of this seed will be covered, and the neighborhood coreness of the neighbors outside the shell layer will be discounted in the subsequent round. The experimental results show that with increases in the spreading probability, the NCCDH outperforms other algorithms in terms of the affected scale and spreading speed under the Susceptible-Infected-Recovered (SIR) and Susceptible-Infected (SI) models. Furthermore, this approach has a superior running time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.8-13
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• 2015

In this study, we fabricated and characterized a nanostructured surface based on a plastic injection molding with a local mold heating (LMH) system. A metal mold core with a closed packed nano convex array (CVA) was achieved by integrated engineering procedures: (1) master template fabrication by anodic aluminum oxidation (AAO), (2) nickel electroforming (NE) process, and (3) post-processing by precision machining. The nickel mold core was utilized to replicate a surface with a closed packed nano concave-array (CCA) based on injection molding using cyclic olefin copolymer (COC) as a plastic material. In particular, an LMH system was introduced to enhance transcription quality of the nano structures by delaying solidification of molten polymer near the surface of the mold core.

• Journal of Korean Society of Rural Planning
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• v.23 no.3
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• pp.1-12
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• 2017

The purpose of this study is to reveal network potential among agricultural villages focused on landscape and amenity resources. For this study, we conducted Social Network Analysis (SNA) utilizing existing landscape resource database. As a result of the study, major landscape types shared among villages were found for each city. For example, agricultural and residential landscapes were identified as major types for Danjin city. Add to major landscape resources, in Dangjin city, Habduk village were recognized as a core. Seokmun, Daehoji, Woogang, and Sunseong villages were widely found as the sub core group. For Seosan city, Jigok, Palbong, and Kobuk villages were widely recognized as core group. Most of villages which indicated the highest degree centrality were superior in terms of the number of total landscape resources as well as landscape type diversity. These results can be useful for initial planning process when considering major theme for landscape-based network organization. Also, this information will be helpful for planning stage through the specification of the potential role of each village in overall network.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.274-278
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• 2003

New banana-shaped achiral compounds, 1,3-phenylene bis [4-{4-(alkenyloxy) phenyliminomethyl}benzoate]s were synthesized by varying the length of alkenyl group; their ferroelectric properties are described. The smectic mesophases, including a switchable chiral smectic C $(Sm\;C^*)$ phase, were characterized by differential scanning calorimetry, polarizing optical microscopy and triangular wave method. The presence of vinyl groups at the terminals of linear side wings in the banana-shaped achiral molecules containing Schiff's base mesogen induced a decrease in melting temperature and formation of the switchable $(Sm\;C^*)$ phase in the melt. The smectic phases having the octenyloxy group such as $(CH_2)_6CH=CH_2$ showed ferroelctric switching, and their values of spontaneous polarization on reversal of an applied electric field were 120 nC/cm² (X=H) and 225 nC/ cm² (X=F), respectively. We could obtain ferroelectric phases by controlling the number of carbon atom in alkenyloxy chain of a bent-core molecule.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2635-2649
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• 2022

CEFR is a small core-size sodium-cooled fast reactor (SFR) using high enrichment fuel with stainless-steel reflectors, which brings a significant challenge to the deterministic methodologies due to the strong spectral effect. The neutronic simulation of the start-up experiments conducted at the CEFR have been performed with a deterministic code system RAST-F, which is based on the two-step approach that couples a multi-group cross-section generation Monte-Carlo (MC) code and a multi-group nodal diffusion solver. The RAST-F results were compared against the measurement data. Moreover, the characteristic of neutron spectrum in the fuel rings, and adjacent reflectors was evaluated using different models for generation of accurate nuclear libraries. The numerical solution of RAST-F system was verified against the full core MC solution MCS at all control rods fully inserted and withdrawn states. A good agreement between RAST-F and MCS solutions was observed with less than 120 pcm discrepancies and 1.2% root-mean-square error in terms of k_eff and power distribution, respectively. Meanwhile, the RAST-F result agreed well with the experimental values within two-sigma of experimental uncertainty. The good agreement of these results indicating that RAST-F can be used to neutronic steady-state simulations for small core-size SFR, which was challenged to deterministic code system.