• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.86-91
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• 2016

Oxidative stress caused by reactive oxygen species is ascribed to many neurodegenerative diseases like Alzheimer's disease. Phenolic antioxidants can reduce the oxidative stress. In this study, ripe fruits of Opuntia ficus-indica var. saboten (OFS) were extracted using 80% (v/v) aqueous ethanol. Total phenolic and flavonoid contents of the OFS fruits (100 g) were 409.9 mg gallic acid equivalents and 72.2 mg catechin equivalents, respectively. The OFS fruits had antioxidant capacity at 381.2, 298.2, and 3,219.9 mg vitamin C equivalents/100 g in ABTS, DPPH, and ORAC assays, respectively. The OFS fruits showed protective effects on PC-12 cells against oxidative stress in a dose-dependent manner, partly due to decrease of intracellular oxidative stress. Furthermore, the OFS fruits inhibited both acetylcholinesterase and butyrylcholinesterase. Consequently, these results suggest that the OFS fruits might be served as a source of functional materials to reduce oxidative stress in neuronal cells and to inhibit cholinesterases.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.819-823
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• 2011

The present study evaluated the seasonal changes of the soil microbial population by selected media in an organic farming system (OFS) with rye rotation cropping management compared to those in a conventional farming system (CFS) with chemical fertilizers, pesticide and herbicide from May 2009 to October 2010 in an upland field. With the exception of fungi, populations of aerobic bacteria, Gram-negative bacteria, and Bacillus spp. were higher in the OFS soil during soybean-growing stages. In addition, populations of aerobic bacteria, Gram-negative bacteria, and Bacillus spp. in the OFS soil were nearly two times more than those in the CFS soil on reproductive growth stages. Our findings suggested that Bacillus spp. should be considered as responsible factor for microbial population differentiation observed between the OFS and the CFS in upland fields.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.814-818
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• 2011

The seasonal changes were evaluated in the soil microbial populations by selected media in an organic farming system (OFS) with no-till management compared to those in a conventional farming system (CFS) with tillage and synthetic amendments in a flooded paddy from 2009 to 2010. The populations of aerobic bacteria and fungi in the OFS were significantly higher than those in the CFS at the harvesting stages, whereas those of Gram-negative bacteria was significantly higher in the OFS than in the CFS before the submerging stages. In addition, populations of aerobic bacteria, Gram-negative bacteria, and fungi tended to rapidly decreased after the submerging stages may be due to insufficient oxygen. Gram-negative bacteria should be considered as potential factor responsible for the microbial population differentiation observed between the OFS and the CFS in flooded paddy fields.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.479-484
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• 2011

Fatty acid methyl ester (FAME) profiles were used to describe differences in soil microbial communities influenced by conventional farming system (CFS), conventional farming system without pesticides (CFSWP), and organic farming system (OFS) for strawberry cultivation in controlled horticultural land. In comparison to the CFS soils, the average soil microbial biomasses of in the OFS soils were approximately 1.2 times for total FAMEs ($195nmol\;g^{-1}$), 1.4 times for total bacteria ($58nmol\;g^{-1}$), 1.5 times for Gram-negative bacteria ($27.3nmol\;g^{-1}$), 1.2 times for Gram-positive bacteria ($26.1nmol\;g^{-1}$), and 1.5 times for actinomycetes ($2.8nmol\;g^{-1}$). The microbial communities of total bacteria (p<0.05) and Gram-negative bacteria (p<0.05) in the OFS and CFSWP soils were significantly higher larger than those in the CFS soils. However, fungal structure was significantly greater in CFS than in OFS and CFSWP (p<0.05). In principal component analyses of soil microbial communities, our findings suggest that actinomycetes should be considered as potential factor responsible for the clear microbial community differentiation observed between OFS and CFS in controlled horticultural land.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.452-456
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• 2011

Glomalin has important roles in soil aggregation in agricultural lands including controlled horticultural lands. The objective of this study was to measure total glomalin content of soils treated conventional farming system (CFS), conventional farming system without pesticides (CFSWP), and organic farming system (OFS) for strawberry cultivation under greenhouse in Goseong-gun, Korea. The average concentration of total glomalin in the soils was significantly higher in the OFS ($2.00mg\;g^{-1}$) compared to the CFS ($1.68mg\;g^{-1}$). In addition, soil microbial biomass C content was 4.9 times higher in the OFS ($821mg\;kg^{-1}$) compared to the CFS ($169mg\;kg^{-1}$). Nitrogen uptake rate of strawberry was higher in the OFS (52.4%) than that in the CFS (13.0%). Furthermore, yield of strawberry in OFS ($51Mg\;ha^{-1}$) was significantly higher compared to CFS ($35Mg\;ha^{-1}$).

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1599-1601
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• 1999

The characteristics of ultrasonic signal in insulation oil were investigated by optical fiber sensor(OFS) utilizing Mach-Zehnder interferometer. For checking the response properties of OFS ultrasonic signal was generated by function generator in various kinds of insulation oil. The attenuation of ultrasonic signal linearly increased with the increase of viscosity of insulation oil in log scale. Discharging signal was produced by neele-sphere electrode system. Intensity of discharging signal was plotted in terms of cumulative $y^2$ and the intensity of discharging signal in new oil was little bigger than that in serviced one.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1563-1565
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• 2000

This paper presents the preliminary results on the application of optical fiber sensor(OFS) for the diagnosis of degradation in the transformer oil. An OFS system using a Mach-Zehnder interferometry technique was built to detect attenuation of acoustic signal produced by discharging. With increasing the number of discharging in the insulation oil, the attenuation of acoustic signal became greater. A strong correlation between electrical and acoustic signal intensities from discharge generated in the transformer oil was confirmed by the results reported here.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.292-302
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• 2022

The radar tomographic imaging is based on the Radar Cross-Section "RCS" of the materials of a shape under examination and investigation. The RCS varies as the conductivity and permittivity of a target, where the target has a different material profile than other background objects in a scene. In this research paper, we use Hierarchical Performance Modeling "HPM" and a framework developed earlier to determine/spot bottleneck(s) for pattern recognition of materials using a combination of the Single Layer Perceptron (SLP) technique and tomographic images in radar systems. HPM provides mathematical equations which create Objective Functions "OFs" to find an average performance metric such as throughput or response time. Herein, response time is used as the performance metric and during the estimation of it, bottlenecks are found with the help of OFs. The obtained results indicate that processing images consumes around 90% of the execution time.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.493.2-493.2
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• 2004

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.695-701
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• 2018

For a power grid that has a high wind penetration level, when wind speeds are continuously fluctuating, the maximum power point tracking (MPPT) operation of a variable-speed wind turbine (VSWT) causes the significant output power fluctuation of a VSWT, thereby significantly fluctuating the system frequency. In this paper, an improved power-smoothing scheme of a VSWT is presented that significantly mitigates the frequency fluctuation caused by varying wind speeds. The proposed scheme employs an additional control loop based on the frequency deviation that operates in combination with the MPPT control loop. To improve the power-smoothing capability of a VSWT in the over-frequency section (OFS), the control gain of the additional loop, which is set to be inversely proportional to the rotor speed, is proposed. In contrast, the control gain in the under-frequency section is set to be proportional to the rotor speed to improve the power-smoothing capability while avoiding over-deceleration of the rotor speed of a VSWT. The proposed scheme significantly improves the performance of the power-smoothing capability in the OFS, thereby smoothing the frequency fluctuation. The results clearly demonstrate that the proposed scheme significantly mitigates the frequency fluctuation by employing the different control gain for the OFS under various wind penetration scenarios.