• Journal of Nutrition and Health
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• v.52 no.5
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• pp.413-421
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• 2019

Purpose: Astragalus membranaceus (AM) is an important traditional medicinal herb. Pharmacological research has indicated that AM has various physiological activities such as antioxidant, anti-inflammatory, immunoregulatory, anticancer, hypolipidemic, antihyperglycemic, and hepatoprotective activities. The bioactive substances responsible for the physiological activities in AM, including many antioxidant substances, change during the roasting process. This study investigated and compared the changes in the antioxidant constituents of AM caused by roasting. Methods: DPPH (1,1-diphenyl-2-picryl hydrazyl) and $ABTS^+$ (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) radical scavenging activities and their total phenolic content (TPC) were measured. High-performance liquid chromatography (HPLC) analysis was performed to confirm any changes in the isoflavonoids of roasted AM (R-AM),. The cell viability of UVB-induced HDF (Human dermal fibroblast) cells treated with AM and R-AM extracts was investigated. The comet assay was used to examine the inhibitory effects of R-AM extracts on DNA damage caused by oxidative stress. Results: The DPPH and $ABTS^+$ radical scavenging activities were $564.6{\pm}20.9$ and $108.2{\pm}3.1$ ($IC_{50}$ value) respectively, from the 2R-AM. The total phenol content was $47.80{\pm}1.40mg$ GAE/g from the 1R-AM. The values of calycosin and formononetin, which are the known isoflavonoid constituents of AM, were $778.58{\pm}2.72$ and $726.80{\pm}3.45{\mu}g/g$ respectively, from the 2R-AM. Treatment of the HDF cells with R-AM ($50{\sim}200{\mu}g/mL$) did not affect the cell viability. Furthermore, the R-AM extracts effectively protected against UVB-induced DNA damage. Conclusion: The findings of this study indicate that R-AM increases its isoflavonoid constituents and protects against UVB-induced DNA damage in HDF cells.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.902-909
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• 2023

This study evaluated the performance test of a small-sized LTE-Maritime(LTE-M) transceiver that was developed and promoted to expand the use of intelligent maritime traf ic information services led by the Ministry of Oceans and Fisheries with the aim of supporting the prevention of maritime accidents. Accoriding to statistics, approximately 30% of all marine accidents in Korean water occur with ships weighing less than 3 tons. Therefore, the blind spots of maritime safety must be supplemented through the development of small-sized transceivers. The small transceiver may be used in fishing boats that are active near coastal waters and in water leisure equipment near the coastline. Therefore, verifying whether sufficient performance and stable communication quality are provided is necessary, considering the environment of their real usage. In this study, we reviewed the communication quality goals of the LTE-M network and the performance requirements of small-sized transceivers suggested by the Ministry of Oceans and Fisheries, and proposed a test plan to appropriately evaluate the performance of small-sized transceivers. The validity of the proposed test method was verified for six real-sea areas with a high frequency of marine accidents. Consequently, the downlink and uplink transmission speeds of the small-sized LTE-M transceiver showed performances of 9 Mbps or more and 3 Mbps or more, respectively. In addition, using the coverage analysis system, coverage of more than 95% and 100% were confirmed in the intensive management zone (0-30 km) and interesting zone (30-50 km), respectively. The performance evaluation method and test results proposed in this paper are expected to be used as reference materials for verifying the performance of transceivers, contributing to the spread of government-promoted e-navigation services and small-sized transceivers.

• Journal of Biosystems Engineering
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• v.10 no.1
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• pp.54-68
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• 1985

It is desirable to collect the solar thermal energy at relatively high temperature in order to minimize the size of thermal storage system and to enlarge the scope of solar thermal energy utilization. So far the concentrating solar collector has been developed to collect solar thermal energy at relatively high temperature, but it has some difficulties in maintaining the volumetric body of solar collector for long term utilization. On the other hand, the flat-plate solar collector has been developed to collect the solar thermal energy at low temperature, and it has advantages in maintaining the system for long term utilization, since it's thickness is thin and not volumetric. In this study, to develop a solar collector that has both advantages of collecting solar thermal energy at high temperature and fixing conveniently the collector system for long term period, a cylindrical parabolic concentrating solar collector was designed, which has two rows of parabolic reflectors and thin thickness such as the flat-plate solar collector, maintaining the optical form of concentrating solar collector. The characteristics of the concentrating parabolic solar collector newly designed was analysed and the results are summarized as follows; 1. The temperature of the air enclosed in solar collector was all the same as $50^{\circ}C$ in both cases of the open and closed loop, and when the heat transfer fluid was not circulated in tubular absorber, the maximum surface temperature of the absorber was $118-120^{\circ}C$, this results suggested that the heat transfer fluid could be heated up to $118^{\circ}C$. 2. In case of longitudinal installation of the solar collector, the temperature difference of heat transfer fluid between inlet and outlet was $4^{\circ}-6^{\circ}C$ at the flow rate of $110-130{\ell}/hr$, and the collected solar energy per unit area of collector was $300-465W/m^2$. 3. The collected solar energy per unit area for 7 hours was 1960 Kcal/$m^2$ for the open loop and 220 Kcal/$m^2$ for the closed loop. Therefore it is necessary to combine the open and closed loop of solar collectors to improve the thermal efficiency of solar collector. 4. The thermal efficiency of the solar collector (C.P.C.S.C.) was proportional to the density of solar radiation, indicating the maximum thermal efficiency ${\eta}_{max}=58%$ with longitudinal installation and ${\eta}_{max}=45%$ with lateral installation. 5. The thermal efficiency of the solar collector (C.P.C.S.C.) was increased in accordance with the increase of flow rate of heat transfer fluid, presenting the flow rate of $110{\ell}/hr$ was the value of turning point of the increasing rate of the collector efficiency, therefore the flow rate of $110{\ell}/hr$ was considered as optimum value for the test of the solar collector (C.P.C.S.C.) performance when the heat transfer fluid is a liquid. 6. In both cases of longitudinal and lateral installation of the solar collector (C.P.C.S.C.), the thermal efficiency was decreased linearly with an increase in the value of the term ($T_m-T_a$)/Ic and the increasing rate of the thermal efficiency was not effected by the installation method of solar collector.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1642-1647
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• 2011

The free radical scavenging activities of extracts from Ligustrum ovalifolium H. leaves (LOH) as well as various antioxidant activities such as ferric reducing antioxidant power (FRAP), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, reducing power and lipid peroxidation inhibition were evaluated by electron spin resonance (ESR). The total polyphenol and flavonoid contents of the water and ethanolic extracts from LOH were $105.5{\pm}1.31$ and $102.1{\pm}1.82$ mg gallic acid equivalent/g extract, respectively, and $84{\pm}1.72$ and $82.8{\pm}1.65$ mg catechin equivalent/g extract. In addition, $IC_{50}$ values for the 1,1-diphenyl-2-picryldrazyl (DPPH), alkyl, and hydroxyl radical scavenging activities of the water and ethanolic extracts were $0.021{\pm}0.002$ and $0.010{\pm}0.003$ mg/mL, $0.011{\pm}0.003$ and $0.012{\pm}0.002$ mg/mL, and $0.395{\pm}0.002$ and $0.443{\pm}0.002$ mg/mL, respectively. The ABTS radical scavenging activities of the water and ethanolic extracts from LOH and BHT were $0.073{\pm}0.12$, $0.130{\pm}0.06$ and $1.461{\pm}0.02$ mM Trolox equivalent/mg extract, respectively. The FRAP values of the extracts from LOH were higher than those of BHT, which was used as a positive control. The LOH extracts showed strong inhibitory effects on lipid peroxidation as measured by ferric thiocyanate (FTC) and thiobarbituric acid (TBA) assay compared to that of ${\alpha}$-tocopherol. Using MTT assay on human liver cells (Chang), extracts from LOH showed no toxicity at a concentration of 0.5 mg/mL. These results indicate that the LOH extracts possessed antioxidant activity.

• The Korean Journal of Pharmacology
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• v.25 no.1
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• pp.43-51
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• 1989

Responsiveness of muscarinic and alpha adrenoceptor activation on endothelial cells was studied in isolated canine renal artery rings. Ach (10-100 nM), dose dependently, relaxes endothelial intact rings precontracted with phenylephrine ($IC_{50}$ of Ach was 34.5 nM). Selective mechanical destruction of the endothelium transformed the activity of this substance from vasodilatation to vasoconstriction. Acetylcholine induced relaxations could be selectively inhibited competitively by atropine, but could not be inhibited by cyclooxygenase inhibitor. Methylene blue, however, an inhibitor of soluble guanylate cyclase activity, inhibited Ach as well as sodium nitroprusside (SNP) induced relaxation. Relaxation produced by prostacyclin was not modified by methylene blue. On the other hand, alpha adrenoceptor agonist did not relax but contract canine renal artery rings possessing an intact intima precontracted with U-46619. Clonidine, however, selective alpha-2 adrenergic agonist, is more susceptible than phenylepherine, selective alpha-1 adrenergic agonist, to the inhibitory effect of contraction. These results suggest that in canine renal artery rings, 1) muscarinic receptor is responsible for releasing endothelium dependent relaxation factor (EDRF). 2) alpha-1 and alpha-2 adrenergic receptors are present in canine renal artery. 3) relaxation via EDRF is antagonized by methylene blue, providing further evidence that EDRF acts through a cGMP mechanism.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.11
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• pp.1525-1531
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• 2011

Antioxidant activity and protective effects of extracts from Helianthus tuberosus L. leaves (HTL) on t-BHP-induced oxidative stress in human liver Chang cells were investigated. The total polyphenol and flavonoid content of the water and ethanolic extracts from HTL were 89.6${\pm}$1.96, 94${\pm}$2.03 mg gallic acid equivalent/g extract, and 65.1${\pm}$2.84, 54.6${\pm}$1.87 mg catechin equivalent/g extract, respectively. In addition, $IC_{50}$ values for 1,1-diphenyl-2-picrydrazyl (DPPH), alkyl, and hydroxyl radical scavenging activity of the water extracts were 0.010${\pm}$0.003 mg/mL, 0.014${\pm}$0.002 mg/mL, and 0.989${\pm}$0.003 mg/mL, respectively. Antioxidant activities of the extracts were also determined by ferric reducing antioxidant power (FRAP), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and reducing power. The HTL extracts showed a strongly inhibitory effect on lipid peroxidation by measuring ferric thiocyanate (FTC) and thiobarbituric acid (TBA) values. In an MTT assay on the Chang cells, the extracts showed a protective effect by increasing cell viability and decreasing ROS on t-BHP-induced oxidative stress in Chang cells. These results indicate that the HTL extracts possess an antioxidant activity.

• The Korean Journal of Food And Nutrition
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• v.30 no.2
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• pp.226-235
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• 2017

Roselle (Hibiscus sabdariffa L.) is a shrub which grows well in a tropical climate. There are large amounts of anthocyanins, organic acids and other compounds in roselle. Mostly, roselle is cultivated to use its red calyx. Its calyx is used as a natural food colorant and commonly consumed as a tea. This quality study was conducted to investigate the characteristics and antioxidant activities of Sulgidduck with roselle calyx powder. Four samples and a control were made with different ratios of added roselle calyx powder (0.5%, 1%, 1.5%, 2%). The moisture content of the 0.5%-sample was the highest as 40.60%, and that of the 2%-sample was the lowest as 37.37%. The pH of samples significantly decreased from 6.26 to 3.65 as the amount of roselle calyx powder increased (p<0.05). The L-value of samples also significantly decreased (p<0.05). In contrast, a-value and ${\Delta}E$ of samples significantly increased with elevated amounts of roselle calyx powder (p<0.05). The b-value of roselle calyx added Sulgidduck samples significantly increased compared to the control (p<0.05). Hardness and chewiness of Sulgidduck samples with added roselle calyx also significantly increased compared to the control (p<0.05). Cohesiveness of Sulgidduck samples with roselle calyx significantly decreased compared to control (p<0.05), with the exception of the 1% sample. There were no significant differences in springiness among samples. Total phenolic contents significantly increased when roselle calyx powder was added above a level of 1.5% (p<0.05). The flavonoid content of the control was the lowest as 0.73. ABTS radical scavenging activity significantly increased with increasing amounts roselle calyx powder (p<0.05). The 2%-sample got the lowest sensory preference scores in sweetness and overall acceptability. In contrast, the control and 1%-sample got the highest sensory preference scores. Based on these study findings, addition of 1% roselle calyx powder optimized the preparation of Sulgidduck and roselle calyx is therefore a useful natural colorant and antioxidant.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.569-574
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• 2007

This study was performed to investigate the biological activities of roasted (RE) and non-roasted (NRE) hot water extract samples from Euonymus alatus leaf by measuring DPPH radical scavenging, total polyphenol content, hydroxyl radical scavenging, superoxide dismutase (SOD)-like activity, anti-inflammatory activity, and inhibitory effects on ${\alpha}-amylase$ and ${\alpha}-glucosidase$ in vitro. The $IC_{50}$ values fur DPPH free radical scavenging activity of the NRE and RE hot water extracts were $19.1{\mu}g/mL$ and $21.9{\mu}g/mL$, respectively, and their total polyphenol contents were estimated as 9.6 mg/g for NRE and 10.6 mg/g for RE. Both NRE and RE scavenged the hydroxyl radical in a concentration-dependent manner, but their activities were lower than that of BHA. It was also shown that SOD-like activity was dependent on NRE and RE concentration, and the SOD-like activity of NRE was slightly higher than that of RE. The highest SOD-like activity obtained from NRE was 20% at a concentration of 3 mg/mL. Neither NRE nor RE seemed to have an effect on ${\alpha}-amylase$ and ${\alpha}-glucosidase$ inhibition. Finally, the hot water extracts of NRE and RE significantly decreased the concentration of LPS-induced NO in RAW 264.7 cells, indicating anti-inflammatory activity.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.9
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• pp.717-722
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• 2001

This paper presents a methodology on the backward path tracking control of a trailer type robot which consists of two parts: a tractor and a trailer. It is difficult to control the motion of a trailer vehicle since its dynamics is non-holonomic. Therefore, in this paper, the modeling and parameter estimation of the system using a real-coded genetic algorithm(RCGA) is proposed and a backward path tracking control algorithm is then obtained based on the linearized model. Experimental results verify the effectiveness of the proposed method.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.564-569
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• 2011

This study qualitatively and quantitatively analyzed various carotenoids, L-ascorbic acid, and tocopherol and their anti-oxidant properties from four varieties (Special, Chelsea, Cupra, and Fiesta) and three different color stages [green (GP), yellow (YP) and red (RP)] of paprika harvested in Korea. Seven carotenoids were identified, mainly lutein in GP (Special: 4.65${\pm}$0.84 mg/kg fresh weight (fw)) and YP (Fiesta: 5.19${\pm}$0.05 mg/kg fw), and capsorubin (3.16${\pm}$0.35 mg/kg fw) and capsanthin (53.70${\pm}$6.23 mg/kg fw) in Special of RP. RP was the highest in total carotenoids, L-ascorbic acid, and ${\alpha}$-tocopherol contents, while GP was the highest in ${\gamma}$-tocopherol content. RP showed the strongest antioxidant activity ($IC_{50}$=62.40${\pm}$0.03 ${\mu}g/mL$ in an ABTS assay and 182.77${\pm}$31.74 ${\mu}g/mL$ in a DPPH assay). Paprika in different color stages has many phytochemicals even though they have different kinds of carotenoids. Therefore, dietary intake of paprika may be helpful for improving human health.