• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.161-171
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• 2019

This study aims the meta analysis based on the results of the empirical studies related to Job of life-long educators who are working in life-long education center, and the relationship between variables. In order to deliver this objective, articles published in domestic journals from December 2000 to April 2019 were collected, and total of 14 studies and 170 sub data were coded. With those data, the meta-analysis was executed by CMA(Comprehensive Meta Analysis) 3.0 program. The results of this meta-analysis study are as follows. First, the overall effect size associated with Job of life-long educators was 0.767, indicating between medium and large effect size. Second, the effect sizes of dependent variables that are influenced by job of life-long educators were Organization immersion, Job performance, Job satisfaction, and Job stress in order. Third, the effect size of Individual focus variables study was almost twice as big as that of mutual relation focus variables. The implications of this study were suggested based on the analysis results to provide the directivity about how we consider life-long educators related to their job.

• Journal of IKEEE
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• v.20 no.2
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• pp.177-180
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• 2016

The effect of varying thickness of Ag/Ti metal bilayer and annealing time have investigated for controlling self-organized nanoparticles (NPs) on 4H-SiC substrate. In addition, Glass and Si substrate which have different surface energy from SiC were fabricated for analyzing interaction of agglomeration. The results of FE-SEM indicated the different formation behaviors of NPs in various ranges of fabrication condition. The surface energy was measured by using a Contact Angle Analyzer. The formation of network-like NPs was observed on Glass and 4H-SiC, respectively, whereas it was not the case on Si substrates. It has been found that the size of NPs increases with decreasing surface energy, due to particle size-dependent hydrophilic properties of substrates. The different formation behavior was explained by using Young's equation for the contact angles between the metal and different substrates.

• Korea Journal of Hospital Management
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• v.9 no.1
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• pp.22-45
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• 2004

This study was performed to identify factors affecting the profitability of private hospitals in Korea different and to make informations that could be very helpful to hospitals in improving profitability. Data used in this study were collected from 112 hospitals with complete general data of present conditions as well as financial statements(balance sheets, income statements). They were chosen from hospitals that passed the standardization audit undertaken by the Korean Hospital Association from 1998 to 2001 for the purpose of accrediting training hospitals. The dependent variables were used operating margin to total assets and operating margin to gross revenues as proxy indicators for profitability. The independent variables were ownership type, location, bed size, period of establishment, debt to total assets, current ratio, fixed ratio, total asset turnover, average length of stay, bed occupancy rate, admission ratio of outpatients, personnel costs per adjusted inpatient, and fiscal years. The factors had significantly positive effect on operating margin to total assets and operating margin to gross revenues were bed size, total asset turnover. And the factors had significantly negative effect on operating margin to total assets and operating margin to gross revenues were period of establishment, debt to total assets, average length of stay, personnel costs per adjusted inpatient. The adjusted $R^2$ of multiple regression equation was 25.2%, 21.4% respectively. It is very important for private hospitals to improve profitability by raising total asset turnover, and reducing debt to total assets, average length of stay, and personnel costs per adjusted inpatient using the rational and efficient business strategy.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.56-56
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• 2003

BaTiO$_3$, SrTiO$_3$단일막과 BaTiO$_3$ (BTO)/SrTiO$_3$ (STO) 산화물 인공격자를 pulsed laser deposition (PLD) 법에 의해서 100 nm 두께의 (La,Sr)CoO3 (LSCO) 산화물 전극이 코핑된 MgO 단결정 기판 위에 증착시켰다. 이러한 기판위에서 2 unit cell의 적층 두께를 갖는 BTO/STO 초격자 (=BTO2/STO2)를 100～5 nm까지 변화시켰다. 또한 BTO와 STO 단일막도 같은 두께로 변화시켰다. 이러한 두께 범위에서 BTO, STO 단일막과 초격자의 격자변형에 따른 유전특성을 살펴 보았다. 두께 변화에 따른 단일막과 초격자의 구조 분석은 포항 방사광 가속기의 x-ray 회절에 의해서 이루어졌다. 다양한 두께를 갖는 BTO2/STO2 초격자에서 BTO와 STO 충은 in-plane 방향으로 격자정합을 유지하면서 변형되었다. 두께가 얇아지면서 하부 LSCO영향으로 BTO, STO의 n-plane 격자상수는 LSCO 격자상수 쪽으로 접근하였다. Out-of-plane 방향의 BTO 격자상수는 두께가 얇아지면서 증가하였고 반면에 STO 격자상수는 감소하였다. STO와 BTO 단일막의 격자변형은 두께가 얇아지면서 in-plane 방향으로 압축응력으로 인해 증가하였다. 그러나, 격자부정합도가 큰 BTO격자에서 더 많이 변형되었다. 또한 초격자에서 BTO격자가 BTO 단일막보다 더 많이 변형되었는데 초격자에서는 BTO, STO 두 층의 발달된 변형뿐만 아니라 하부 LSCO/MgO 기판의 영향을 함께 받고 있기 때문이다. 초격자와 단일막의 유전상수를 살펴보면은 두께가 감소하면서 유전상수가 감소하는 size effect을 보이고 있다. 하지만 초격자에서의 유전상수가 단일막보다 우수한 유전특성을 보이고 있다. 이러한 결과로 볼 때 격자변형이 size effect 영향을 끼치는 중요한 요소임을 확인하였다.

• Environmental Analysis Health and Toxicology
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• v.28
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• pp.3.1-3.8
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• 2013

Objectives We investigated the genotoxic effects of 40-59 nm silver nanoparticles (Ag-NPs) by bacterial reverse mutation assay (Ames test), in vitro comet assay and micronucleus (MN) assay. In particular, we directly compared the effect of cytochalasin B (cytoB) and rat liver homogenate (S9 mix) in the formation of MN by Ag-NPs. Methods Before testing, we confirmed that Ag-NPs were completely dispersed in the experimental medium by sonication (three times in 1 minute) and filtration ($0.2{\mu}m$ pore size filter), and then we measured their size in a zeta potential analyzer. After that the genotoxicity were measured and especially, S9 mix and with and without cytoB were compared one another in MN assay. Results Ames test using Salmonella typhimurium TA98, TA100, TA1535 and TA1537 strains revealed that Ag-NPs with or without S9 mix did not display a mutagenic effect. The genotoxicity of Ag-NPs was also evaluated in a mammalian cell system using Chinese hamster ovary cells. The results revealed that Ag-NPs stimulated DNA breakage and MN formation with or without S9 mix in a dose-dependent manner (from $0.01{\mu}g/mL$ to $10{\mu}g/mL$). In particular, MN induction was affected by cytoB. Conclusions All of our findings, with the exception of the Ames test results, indicate that Ag-NPs show genotoxic effects in mammalian cell system. In addition, present study suggests the potential error due to use of cytoB in genotoxic test of nanoparticles.

• Management & Information Systems Review
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• v.28 no.2
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• pp.95-112
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• 2009

The paper investigates the determinants of firm's standardization activity in the Korean service industry. Standardization variables as dependent ones are standardization management at the firm level, domestic standardization activity, and international standardization activity. The independent variables include innovative activities(R&D intensity and patent application), firm size, export ratio, network, and firm's organization characteristics. We estimated the logistic regression model, using the data from 102 Korean service firms. The empirical findings are as follows. First, R&D intensity has a positive effect on international standardization activity, but not on the standardization management at the firm level and domestic standardization activity. Second, patent application has a negative effect on the standardization management at the firm level. Third, firm size doesn't have any influence on firms' standardization activities in the service sector. Fourth, the level of chief executive officer's interest on standardization is a very important factor in determining firms' efforts to participate standardization process, regardless of types of standardization activity.

• Journal of Pharmaceutical Investigation
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• v.36 no.5
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• pp.299-304
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• 2006

The aim of this study was to investigate the effect of deformable liposomes with sodium cholate on the skin permeation and skin deposition of arbutin, a hydrophilic skin-whitening agent. Various compositions of liposomes were prepared by the extrusion method. Particle size distribution and entrapment efficiency were determined by the laser light scattering and the gel permeation chromatography, respectively. The in vitro rat skin permeation and deposition of arbutin in various skin layers were investigated using the Keshary-Chien diffusion cells at $37^{\circ}C$. The average particle size of the deformable liposomes ranged from 217.4 to 117.4 nm, depending on the composition. The entrapment efficiency was dependent on surfactant concentration and loading dose of arbutin. The permeation rate of 5% arbutin in deformable liposomes was $8.91({\pm}1.33){\mu}g/cm^2/h$, and was not significantly different from 5% arbutin aqueous solution $[9.82({\m}0.86){\mu}g/cm^2/h]$. The deposition of arbutin was $43.34({\pm}12.13)$ and $16.99({\pm}7.83){\mu}g/cm^2$ in stratum corneum layer and epidermis/dermis layer, respectively, after 12 h of permeation study. These results are consistent with several earlier studies for the localization effect of liposomal formulations in stratum corneum, and demonstrated the feasibility of the deformable liposomes as a promising carrier for the skin deposition of hydrophilic skin-whitening compounds.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.725-734
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• 1996

Shrinkage behaviors associated with forming drying and firing processes could be a driving force for the densification in materials. Low shrinkage-densification behaviors in clay materials have been shown to be highly dependent upon the processing parameters including particle size effect and kinetic behaviors caused by phases transformation characteristics. Chamottes pre-treated at 90$0^{\circ}C$ and 120$0^{\circ}C$ had dominent influence upon shrinkage control of materials during heat-treatment. But Coarse chamotte particles heat-treated at 120$0^{\circ}C$ did not contri-bute to any densification behaviors in clay materials while these added coarse particles could enhance near-net-shape control. Microstructure / property relationships in clay materials have been thought to be directly influenced by optimized characteristics between low shrinkage and densification behaviors.

• Korean Journal of Materials Research
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• v.32 no.11
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• pp.466-473
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• 2022

The effect of Cr and Mo contents on the hydrogen embrittlement of tempered martensitic steels was investigated in this study. After the steels with different Cr and Mo contents were austenitized at 820 ℃ for 90 min, they were tempered at 630 ℃ for 120 min. The steels were composed of fully tempered martensite with a lath-type microstructure, but the characteristics of the carbides were dependent on the Cr and Mo contents. As the Cr and Mo contents increased, the volume fraction of film-like cementite and prior austenite grain size decreased. After hydrogen was introduced into tensile specimens by electrochemical charging, a slow strain-rate test (SSRT) was conducted to investigate hydrogen embrittlement behavior. The SSRT results revealed that the steel with lower Cr or lower Mo content showed relatively poor hydrogen embrittlement resistance. The hydrogen embrittlement resistance of the tempered martensitic steels increased with increasing Mo content, because the reduction in the film-like cementite and prior austenite grain size plays an important role in improving hydrogen embrittlement resistance. The results indicate that controlling the Cr and Mo contents is essential to achieving a tempered martensitic steel with a combination of high strength and excellent hydrogen embrittlement resistance.

• Journal of Practical Engineering Education
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• v.12 no.2
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• pp.363-369
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• 2020

This study intends to examine effects of python education for adolescents. 6 primary studies were chosen through careful search process and investigated through meta-analysis. Research findings were as follows. The total effect size was 0.684. Second, the effect sizes of dependent variables were academic achievement 0.871, cognitive domain 0.625, and affective domain 0.428 in order. Third, for cognitive domain, the effect sizes were self-efficacy 0.833, problem-solving 0.283, computing thinking 0.276, and coding competency 0.251 in order. Fourth, for affective domain, the effect sizes were learning interest 0.560 and programming interest 0.417 in order. Fifth, regarding school level, the effect sizes were middle school 0.851, high school 0.585, and college 0.435 in order. Finally, for subject areas, the effect sizes were mathematics 1.057, design 0.595, information 0.585, and software 0.28 in order.