• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.254-259
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• 2021

Optical and electrical characteristics of the fluorocarbon films deposited in a high-density C4F8 plasma under various source powers and pressures were investigated. The F/C ratio of the fluorocarbon film deposited in a high-density C4F8 plasma increased with increasing source power and decreasing pressure due to two-step deposition mechanism. The change in the F/C ratio of the film directly affected the optical and electrical characteristics of the fluorocarbon films deposited in a high-density C4F8 plasma. The refractive index of the fluorocarbon film increased with decreasing source power and increasing pressure contrary to the dependence of the film's F/C ratio on the source power and pressure. This was because the increase in the F/C ratio suppressed electronic polarization and weakened the network structures of the film. The resistivity of the fluorocarbon film showed the same behavior as its F/C ratio. In other words, the resistivity increased with increasing source power and decreasing pressure, resulting from stronger repellence of electrons at higher F/C ratios. This work offers the feasibility of the use of the fluorocarbon films deposited in a high-density C4F8 plasma as an alternative to low dielectric constant materials because the optical and electrical properties of the fluorocarbon film can be directly controlled by its F/C ratio.

• Korean Journal of Food Science and Technology
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• v.50 no.6
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• pp.671-679
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• 2018

Glasswort has attracted an attention because of its interesting physiological actions. In this study, the effects of glasswort on inflammatory events including nitric oxide (NO) synthesis and arachidonic acid metabolism in cultured RAW264.7 macrophages were investigated. A series of solvent fractions, including fractions of hexane (Fr.H), ethyl ether (Fr.E), ethyl acetate, butanol, and water, were prepared from a 70% methanol extract of glasswort. Among the fractions, Fr.E showed the strongest inhibition of NO synthesis and inducible NO synthase (iNOS) expression in lipopolysaccharide (LPS)-stimulated macrophages. At a concentration of $80{\mu}g/mL$, Fr.E decreased the NO and iNOS levels by 73 and 77%, respectively, after 24 h. Fr.E showed the most potent inhibitory effects on the expressions of cytosolic phospholipase $A_2$ and cyclooxygenase-2 with $IC_{50}$ values of 33.4 and $27.9{\mu}g/mL$, respectively. Fr.H and Fr.E also significantly inhibited 5-lipoxygenase expression in LPS-stimulated macrophages. These results suggest that the hydrophobic fractions of glasswort possess anti-inflammatory activities through modulating the arachidonic acid metabolism and NO synthesis.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.582-594
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• 2018

In this study, the vertical and horizontal flow wetlands were combined in series to create conditions for flow in the exhalation and anaerobic state with the aim of monitoring the variability and reduction of dissolved organic matterin the bio-reactive artificial wetlands, and the performance assessment was conducted as acrylic reaction groups by designing artificial wetlands that filled the functionalresiduals. In case of artificial wetlands in vertical and horizontal planes, the concentration of dissolved oxygen (DO) in the reaction tank was measured as 2.7 mg/L in the vertical flow wetlands under exhalation, and N.D. in the horizontal flow artificial wetlands under anaerobic conditions. The test was carried out by changing the operation time to 140 min, 80 min, and 60 min. The test was conducted with the same natural operation time of 20 min depending on the operation time. All hours of operation were shown to be due to microbial activity. In 3D-EEM, it was found that the longer the driving time was taken, the more reduction the organic compounds in the areas of insoluble human resources, III and V. Further research on the mechanism analysis of future reduction effects is expected to be carried out, but the findings are expected to contribute to the development of technologies for reducing obfuscated substances using artificial wetlands in the future.

• Korean Journal of Food Science and Technology
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• v.51 no.1
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• pp.90-96
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• 2019

Unripe astringent persimmon (Diospyros kaki Thunb. cv. Cheongdo-Bansi) is a by-product produced when thinning out the superfluous fruit of persimmon. We investigated whether unripe astringent persimmon has antioxidative and anti-inflammatory effects. Unripe astringent persimmon extract was fractionated sequentially in n-hexane, chloroform, ethyl acetate, n-butanol, and water. The ethyl acetate fraction had the highest total phenolic content, total flavonoid content, and antioxidant capacity compared to those of the other fractions. Pretreatment of lipopolysaccharide-stimulated RAW 264.7 macrophages with the ethyl acetate fraction reduced nitric oxide, interleukin-6, and intracellular oxidative stress in a dose-dependent manner. Ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis revealed gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, quercetin-3-O-glucoside, quercetin, and p-coumaric acid as the phenolic compounds of the ethyl acetate fraction. Collectively, these findings suggest that unripe astringent persimmon is a source of functional materials that can promote antioxidative and anti-inflammatory effects.

• Korean Journal of Food Science and Technology
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• v.50 no.6
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• pp.653-659
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• 2018

In this study, we investigated the antioxidant activities and anti-aging efficacy in terms of suppression of matrix metalloproteinases (MMPs) in UVB-irradiated HaCaT cells by adding the ethanol extracts of Josaengheogchal (JE) and Shintoheug rice (SRE). In the electron-donating ability and ABTS radical-scavenging assays, we observed that both JE and SRE had scavenging activities and in a collagenase inhibition assay, both extracts showed inhibition effects of over 73% at $1,000{\mu}g/mL$ concentration. The expression of MMP-1 and -3, when the extracts were treated with UVB $50mJ/cm^2$, irradiated human HaCaT keratinocytes, was analyzed by western blotting and reverse-transcription polymerase chain reaction (RT-PCR). The results showed that MMP-1 and -3 proteins and mRNAs were downregulated in a concentration-dependent manner in response to both extracts. Therefore, we expect that these compounds have a potential for the use as functional ingredients with anti-aging effects in the cosmetic and food industries.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.83-88
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• 2019

BACKGROUND: In recent years, studies on microplastics have focused on their decomposition in the ocean. However, no studies have been reported on the interaction between microplastics and metal ions in aqueous solutions. Therefore, this study was conducted to evaluate the adsorption capacity of cadmium(Cd) by polypropylene (PP) in aqueous solution. METHODS AND RESULTS: Cadmium adsorption characteristics of PP in aqueous solution were evaluated through various conditions including initial Cd concentration(1.25-25 mg/L), contact time(0.5-24 h), initial pH(2-6) and temperature($20-50^{\circ}C$). Cadmium adsorption fit on PP was well described by Freundlich isotherm model with adsorption capacity(K) of 0.028. The adsorption amount of Cd by PP increased with increasing contact time, indicating that adsorption of PP by Cd was dominantly influenced by contact time. Especially, the removal efficiency of Cd by PP was highest at high temperature. However, the surface functional groups of PP before and after adsorption of Cd were similar, suggesting that adsorption of Cd by PP is not related to surface functional groups. CONCLUSION: Our study suggests that PP affects the behavior of Cd in aqueous solution. However, in order to clarify the specific relationship between microplastics and metal ions, mechanism research should be carried out.

• Korean Journal of Heritage: History & Science
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• v.44 no.3
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• pp.92-111
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• 2011

This study focus on the restoration stone selection of break-out part based on material characteristics analysis and the conservational safety diagnosis using various nondestructive techniques for Jungdong and Banjukdong Stone Auariums. As a result, the original rocks of the stone aquariums body are porphyritic granodiorite with magnetite-series having igneous lineation, microcline phenocryst, veinlet and basic xenolith. As a result of the provenance presumption of the host rock, a rock around Gamgokri area in Nonsan City was identified the genetically same rock. Therefore, the rock is appropriate for restoration materials of the break-out part. The deterioration assessment showed that the stone aquariums were highly serious scaling, scale off and blackening. Particularly, the front face of Banjukdong stone aquarium needs reinforcement of structural crack (760mm) caused from igneous lineation of biotite. Blackening contaminants on the stone aquariums surface occurred by combining iron oxide, manganese oxide and clay mineral. Also, major factors of efflorescence contaminants were identified as calcite (Jungdong stone aquariums) and gypsum (Banjukdong stone aquariums). The physical characteristics of stone aquariums appeared that the original and new stone is third (moderately weathered) and second grade (slightly weathered), respectively. This study sets up an integrated conservation system from material analysis to restoration stone selection and conservational safety diagnosis of Jungdong and Banjukdong stone aquariums.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.175-181
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• 2019

In the case of a conventional single stage decompression regulator used for large depressurization in the hydrogen fuel cell system of a fuel cell electric vehicle (FCEV), problems can arise, such as pulsation, slow response, hydrogen brittleness, leakage, high weight, and high cost due to high decompression. Most of these problems can be overcome easily using two decompression mechanisms (two-stage structures). In addition, a wide outlet-pressure control range can be secured if an electronic solenoid is applied to the second decompression. Accordingly, it is necessary to improve the precision of the outlet pressure of a two-stage pressure-reducing regulator and develop techniques, such as leakage prevention, durability, light weight, and price reduction. Therefore, to improve the outlet pressure accuracy and prevent leakage, the structural part before and after decompression to improve the air tightness were divided and the analysis was carried out assuming that the valve part was closed (open ratio: 0%) after each initial internal pressure application.

• Management & Information Systems Review
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• v.38 no.2
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• pp.47-66
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• 2019

The purpose of this study is to investigate the mediating role of proactive behaviors in the mechanism which job crafting affects organizational effectiveness. Through this study, we tried to contribute to the following theoretical and practical aspects. First, we tried to extend the theoretical discussion by identifying the relationship between job crafting, proactive behavior, and organizational effectiveness. Second, we provide practical implications for Korean organizational members based on proven job crafting, proactive behavior, and organizational effectiveness, and contribute to creating a work environment that enhances job satisfaction and reduces turnover intention. The results of this study are as follows. First, increasing structural job resource, increasing social job resource and increasing challenging job demand, which are sub-factors of job crafting, had a positive effect on job satisfaction. Second, increasing structural job resource, increasing social job resource and increasing challenging job demand, which are sub-factors of job crafting, had a negative effect on turnover intention. Third, job crafting had a positive effect on proactive behavior. Fourth, proactive behavior mediated the relationship of increasing structural job resource, increasing social job resource, increasing challenging job demand, and job satisfaction. Fifth, proactive behavior mediated the relationship of increasing structural job resource, increasing social job resource and turnover intention. This study provides an understanding of the impact of job crafting on organizational effectiveness and is expected to contribute to future research on job crafting.

• The Korean Journal of Applied Statistics
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• v.32 no.4
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• pp.543-559
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• 2019

Data often include missing values due to various reasons. If the missing data mechanism is not MCAR, analysis based on fully observed cases may an estimation cause bias and decrease the precision of the estimate since partially observed cases are excluded. Especially when data include many variables, missing values cause more serious problems. Many imputation techniques are suggested to overcome this difficulty. However, imputation methods using parametric models may not fit well with real data which do not satisfy model assumptions. In this study, we review imputation methods using nonlinear models such as kernel, resampling, and spline methods which are robust on model assumptions. In addition, we suggest utilizing imputation classes to improve imputation accuracy or adding random errors to correctly estimate the variance of the estimates in nonlinear imputation models. Performances of imputation methods using nonlinear models are compared under various simulated data settings. Simulation results indicate that the performances of imputation methods are different as data settings change. However, imputation based on the kernel regression or the penalized spline performs better in most situations. Utilizing imputation classes or adding random errors improves the performance of imputation methods using nonlinear models.