• Journal of the Korean Society of Food Culture
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• v.35 no.4
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• pp.392-399
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• 2020

This study examined the contents of bioactive compounds and the biological activity of okra seed oil. Okra seed oil consisted mainly of linoleic acid (44.2%). The content of total phytosterols was 2.180 mg/g oil, with β-sitosterol being the highest (1.756 mg/g oil). The vitamin E content was 1.278 mg/g oil; the content of α-tocopherol was higher than γ-tocopherol. The total polyphenol and flavonoid contents were 2.463 mg gallic acid equivalent/g and 1.602 mg cathechin equivalent/g, respectively. The 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid and α-α-diphenyl-β-picrylhydrazyl free radical scavenging activities were 15.297% and 22.265%, respectively, and the reducing power was 4.524 mg gallic acid equivalent/g. The okra seed oil inhibited 77.692% of the α-glucosidase activity. The present study showed that okra seed oil had a considerable amount of phytochemicals and exhibited biological activity. These results suggest that okra seed oil is a potential natural therapeutic for the management of metabolic syndromes.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.320-325
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• 1992

For natural antioxidant test, the Rhus javanica $Linn\'{e}$ was extracted by 75% ethyl alcohol and fractionated it by chloroform and ethyl acetate using separatory funnel and column chromatography. In the Rhus javanica L. extract, the effective material was disolved easily in ethyl acetate and chloroform. When 600 ppm of ethyl acetate fraction of the extract was added to palm oil and lard, AI(antioxidant index) of each oil was 1.60 and 3.90 respectively. The $CHCl_3$ and EtOAc fractions were more effective than whole extract of Rhus javanica L. The palm oil, lard and soybean oil containing different levels of the Rhus javanica L. extract were stored at $60^{\circ}C$ to compare their antioxidative activity. Peroxide value, acid value and TBA value of each oil were monitored. The Rhus javanica L. extract was very effective to retard oxidation of palm oil and lard. This result coincided with Ranimat test.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.7
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• pp.1175-1179
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• 2004

Structured lipid (SL) was produced from soybean oil with molar ratio of 1：2：2 (soybean oil：capric acid：CLA) using Chirazyme L-2 lipase (4％ by weight of total substrates). The reaction was conducted for 24 hr at 55$^{\circ}C$ in a 1 L stirred-batch type reactor. SL-soybean oil contained 4.9 mol％ capric acid and 4.1 mol％ CLA, respectively. Iodine value of SL-soybean oil was reduced than that of soybean oil due to the incorporated capric acids. Tocopherol content in SL-soybean oil was 18.2 mg/l00 g. SL-soybean oil appeared more yellowish color than soybean oil. Reverse-phase HPLC showed that SL-triacylglycerol species containing capric acid consisted of about 12.6 area％.

• The Korean Journal of Food And Nutrition
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• v.14 no.6
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• pp.591-595
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• 2001

The antioxidant and synergistic effects of sesame oil cake extract treated with $\beta$ -glucosidase were examined. The sesamin and sesamolin were identified from the 80% ethanol extract of seame oil cake treated with $\beta$ -glucosidase, which suggested the presence of the active substances as their glycosides in sesame seed. The contents of sesamin and sesamolin in sesame oil cake extract were about 8.32% (8,315.4 mg/100g) and 0.28% (2,824.5mg/100g) , respectively. Sesame oil cake extract showed antioxidant activity at concentrations of 50ppm, 100ppm and 200ppm, and the effect was Increased with the addition of sesame oil cake extract. The antioxidant effect of sesame oil cake extract was stronger than that of $\alpha$-tocopherol or ascorbyl palmitate, but weaker than of BHT Also, when the sesame oil cake extract(50ppm) was used in combination with $\alpha$-tocopherol(50 ppm), the sesame oil cake showed very strong synergistic effect.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2333-2341
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• 2017

Mineral oils are commonly used as transformer insulation oils but these oils are obtained from non-renewable and non-sustainable sources, which is highly undesirable. For this reason, natural ester oils are now being used in replacement of mineral oils because of their good biodegradability, high cooling stability, good oxidation stability and excellent insulation performance. Nanotechnology has gained prominence in both academic and industrial fields over the years and it has been shown in previous studies that nanoscale materials are useful for transformers due to their favourable dielectric properties. The objective of this study is to compare the AC breakdown voltage and viscosity of natural ester oil with three types of nanofluids. The natural ester oil-based nanofluids are prepared by mixing palm fatty acid ester (PFAE) oil with three types of nanoparticles at a concentration of 0.01 g/l: (1) $Fe_3O_4$ conductive nanoparticles, (2) $TiO_2$ semi-conductive nanoparticles and (3) $Al_2O_3$ insulating nanoparticles. The AC breakdown voltage of the oil samples is analysed using Weibull statistical analysis and the results reveal that the PFAE oil-based $Fe_3O_4$ nanofluid gives exceptional dielectric performance compared to other oil samples, whereby the AC breakdown voltage increases by 43%. It can be concluded that the PFAE oil-based $Fe_3O_4$ nanofluid is a promising dielectric liquid to substitute mineral oils.

• Resources Recycling
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• v.15 no.1 s.69
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• pp.12-19
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• 2006

Rice straw is one or the main renewable energy sources in Korea. Bio-oil is produced from rice straw with a lab-scale equipment mainly with a fluidized bed and a char removal system. It was investigated how the reaction temperature affected the production of bio-oil and the efficiency of a char removal system. To elucidate how the temperature depended on the production of bio-oil, experiments were conducted at $466^{\circ}C,\;504^{\circ}C\;and\;579^{\circ}C$, respectively. The mass balance was established in each experiment, and the produced gas and oil were analyzed with the aid of GCs and a GC-MS system. The char removal system is composed of a cyclone and a hot filter. Tn the experiments, we observed that the production of bio-oil was decreased with temperature, and the bio-oil contained very useful chemicals.

• Korean Journal of Remote Sensing
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• v.29 no.6
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• pp.645-655
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• 2013

As one of segmentation techniques for Synthetic Aperture Radar (SAR) image with oil spill, we applied a bimodal histogram method to discriminate oil pixels from non-oil pixels. The threshold of each moving window was objectively determined using the two peaks in the histogram distribution of backscattering coefficients from ENVISAT ASAR image. To reduce the effect of wind speed on oil spill detection, we selected ASAR image which satisfied a limit of wind speeds for successful detection. Overall, a commonly used adaptive threshold method has been applied with a subjectively-determined single threshold. In contrast, the bimodal histogram method utilized herein produces a variety of thresholds objectively for each moving window by considering the characteristics of statistical distribution of backscattering coefficients. Comparison between the two methods revealed that the bimodal histogram method exhibited no significant difference in terms of performance when compared to the adaptive threshold method, except for around the edges of dark oil spots. Thus, we anticipate that the objective method based on the bimodality of oil slicks may also be applicable to the detection of oil spills from other SAR imagery.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.184-191
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• 2016

In recent years, there are a number of studies that have been carried out to explore the alternative for Mineral Oil (MO) as dielectric insulating fluid in transformers due to the increasing tight regulation on safety and environment. Vegetable oils have been identified as suitable candidate since it is biodegradable, non-toxic and high flash/fire points which ensure more in-service safety. Among the types of vegetable oils considered for transformers application are Palm Oil (PO) and Coconut Oil (CO). This paper presents an experimental study on the lightning breakdown voltages of PO and CO under non-uniform electric field based on needle-sphere electrodes configuration at 3 small gap distances. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The main focus of this study is to examine the lightning breakdown performance of RBDPO and CO under different test conditions and assess its suitability as dielectric insulating fluid in transformers. The effect of voltage polarities (positive and negative) and testing methods (rising-voltage, up-and-down and multiple-voltage) were investigated. The data obtained from all tests were analysed by Weibull distribution in order to determine the withstand voltages for each type of oils. It was found that the breakdown voltages of RBDPO and CO are comparable with MO under positive lightning impulse. Under negative lightning impulse, the breakdown voltage of MO is slightly higher than RBDPO and CO. There is no significant effect of testing methods and voltage polarities on lightning breakdown voltages of RBDPO and CO. Based on the statistical analysis, it is found that the breakdown voltages of RBDPO and CO at 1% probability are slightly lower than MO.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1512-1519
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• 2013

Oil-impregnated paper is a major type of insulation used in oil-filled converter transformers for both traditional and new energy systems. This paper presents and analyzes the results of the experiment conducted on the electrical aging of oil-impregnated paper under AC-DC combined voltages using the pulsed electro-acoustic (PEA) technique. The formation and dynamics of space charge affected the performance of insulation material. The electrical aged oil-paper insulation was obtained through electrical aged experiments under the voltages. Based on the PEA technique, measurements were carried out when the oil-paper insulation system was subjected to different stressing and aging times. The space charge dynamics in the bulk of the oil-paper insulation system with different aging times were measured and analyzed. Characteristic parameters such as the total charge injection amount, the total charges of fast moving and slow moving, and the distortion factor of electric field were calculated and discussed. Results show that the longer electrical aging time, the more charges trapped in the bulk of aging sample. It leads to larger distortion factor of electric field in the bulk of aging samples and accelerate degradation of oil-paper insulation under AC-DC combined voltages.

• Korean Journal of Organic Agriculture
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• v.26 no.2
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• pp.259-268
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• 2018

The study investigated the efficacy of four different essential oils on the repellent responses of large black chafer (Holotrichia parallela) Motschulsky (Coleoptera: Scarabaeidae) in organic pear (Pyrus pyrifolia) orchards. Cinnamon, pine, peppermint, and eucalyptus oils were used, and the behavioral responses and repellent effects against H. parallela were investigated under laboratory and field conditions. Adult beetle responses to different oils were examined using a Y-tube olfactometer in the laboratory and four absorbent blocks with each oil in the field. The repellent responses rates of H. parallela were 100% for cinnamon oil; however, only 67% of adult beetles avoided peppermint and eucalyptus oil in the Y-tube olfactometer bioassay. In the field tests, the least damage to leaves was observed on trees treated with cinnamon oil, whereas the most damage was observed in the control (non-treated) trees and those treated with peppermint oil, followed by eucalyptus and pine oil. Therefore, cinnamon oil can be used as a repellent to avoid damage form large black chafers in organic pear orchards.