• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.51-64
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• 2000

This paper presents a procedure of calculating a safety factor of the unsaturated slope suffering from the rainfall infiltration. The process of infiltration into a slope due to rainfall and its effect on the behavior of the soil slope are examined by using a two dimensional finite element flow-deformation coupled analysis. A factor of safety is calculated at various elapsed times after the commencement of rainfall as in the following procedure. First, stresses are estimated at each Gaussian point from the coupled finite element analysis. Then, the global stress smoothing method is applied to get a continuous stress field. Based on this stress field, a factor of safety is calculated for a specified slip surface by a stress integration scheme. Then, a search strategy is used to find out a critical slip surface which is associated with the minimum factor of safety. Some numerical examples are analyzed in order to study the effect of hydraulic conductivity on the slope stability during rain-induced infiltration. According to the results, local failure zone can be formed near the slope surface due to inhomogeneous distribution of hydraulic conductivity If the failure zone is once formed, then the region extends until a large amount of slide activates. Therefore the local failure can be neglected no longer in the stability analysis.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.440-449
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• 2018

Purpose: This study aims to design and verify an onsite EEWS that extracts the P-wave from a single seismic station and deduce the PGV. Method: The P-wave properties of Pd, Pv, and Pa were calculated by using 12 seismic waveform data extracted from historic seismic records in Korea, and the PGVs were computed using empirical equation on the P properties - PGV relationship and compared with the observed values. Results: Comparison of the observed and estimated PGVs within the alarm level shows the error rate of 86.7% as minimum. By reducing the PTW to 2 seconds, the alarm time can be shortened by 1 second and the seismic blind zone near the epicenter can be shortened by 6 Km. Conclusion: Through this study, we confirmed the availability of the on-site EEWS in Korea. For practical use, it is necessary to develop regression formula and algorithm reflect local effect in Korea by increasing the number of seismic waveform data through continuous observation, and to eliminate the noise from the site.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.661-676
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• 2000

Gingivitis and periodontitis are infectious diseases in that microorganisms are the primary extrinsic cause of the diseases. the occurrence of gingivitis has been associated clearly with the presence of microorganisms at the disease site, and the histologic nature of the tissue involved is indicative of an inflammatory response induced by microorganisms. additional evidence for the microbial etiology of periodontal disease is that numerous antimicrobial agents are effective in reducing plaque accumulation and periodontal diseases. the purpose of this article is to analyze the antimicrobial effects of Pulsatilla koreana. Well-dried Pulsatilla koreana purchased from herbs distributor was ground and extracted into methanol(MeOH), ethylacetate(EtoAc), chlorform($CHCl_3$) and Butyl alcohol(BuOH). we have then applied each solution to the bacteria samples(Bacteroides forsythus, Streptococcus mutans, Streptococcus sanguis, Porphylomonas gingivalis, Actinobacillus actinomycetemcomitans, Eikenella corrodens, Prevotella intermedia, Actinomyces viscosus, Prevotella nigrescens , Rothia dentocariosa, Fusobacterium nucleatum, Pseudomonas aeruginosa, Staphylococcus aureus) collected from several organizations. To conduct susceptibility test(Kirby-Bauer method), plate contained each periodontopathic bacteria is spread extracted into methanol(MeOH), ethylacetate(EtoAc), chlorform($CHCl_3$) and Butyl alcohol(BuOH) and to measure the minimum inhibition concentration(MIC) of the bacteria against the solutions to ultimately determine antimicrobial effects of the solutions, insert bacteria sample into $20{\mu\ell}/{m\ell}$, $10{\mu\ell}/{m\ell}$, $5{\mu\ell}/{m\ell}$, $2.5{\mu\ell}/{m\ell}$ of each solution and control group(not contained solution) 1. Solution extracted into methanol did not show clear zone against all bacteria samples. Only P.nigrescens, S. mutans and S. sanguis in solution extracted into ethylacetate, S. mutans and S. anguis in solutions extracted into chlorform and Butyl alcohol showed clear zone against all bacteria samples. Solution extracted into Butyl alcohol showed clear zone against 13 types of bacteria, excluding P. gingivalis. 2. In Solution extracted into methanol, the bacteria samples grew in the highest concentrated plate, showing minimal variation from control group. 3. In Solution extracted into Butyl alcohol, S. aureus, P. intermedia, E. corrodens, A. actinomycetemcomitans, B. forsythus, P. gingivalis et al. showed decreased growth in the highest concentrated plate. P. auruginosa, R. dentocariosa, A. viscosus, P. nigrescens, S. mutans et al. showed decreased growth at MIC $20{\mu\ell}/{m\ell}$ and S. sanguis showed decreased growth at MIC $10{\mu\ell}/{m\ell}$. 4. By analyzing the MIC level through considering the results from Kirby-Bauer method, Solution extracted into methanol did not reveal any antimicrobial effects and Solution extracted into Butyl alcohol showed the highest antimicrobial effects In conclusion, it can be used the extracts of Pulsatilla koreana as wide spectrum antimicrobial agent.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.146-150
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• 2017

Staphylococcus aureus is a pathogenic bacterium that causes food poisoning, exhibits a strong capacity to form biofilm, and is highly resistant to antimicrobial agents. The purpose of this study was to investigate the antimicrobial characteristics of corosolic acid against S. aureus. S. aureus showed high susceptibility to corosolic acid in a concentration-dependent manner. The minimum inhibitory concentration and colony-forming ability determined by the broth microdilution method showed that corosolic acid had strong antimicrobial activity against the bacteria. The diameters of the inhibition zone and numbers of colony forming units at each concentration of corosolic acid were also measured. In addition, corosolic acid displayed potent biofilm inhibition activity against S. aureus at concentrations below its minimum inhibitory concentration. These results suggest that corosolic acid can be used to effectively prevent biofilm formation by S. aureus, thereby making S. aureus more susceptible to the action of antimicrobials.

• Journal of the Korean Applied Science and Technology
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• v.37 no.1
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• pp.145-152
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• 2020

In this study, the antimicrobial activity was tested by Ethanol extract(ET), Ethyl acetate fraction(EA) and Butanol fraction(BT) of Rhus javanica L fruit as natural preservatives. The antimicrobial activity were tested by Paper disc method and minimum inhibitory concentration (MIC) for microorganisms (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Candida Albicans). As a result of the antimicrobial activities of P. aeruginosa fruit extracts have shown the clear zone that S. aureus, S. epidermidis, E. coli, and P. aeruginosa. In BT, additional clear zones were observed for the Candida. The MIC results showed that EA samples showed the lowest concentrations for S. aureus S. epidermidis, E. coli, and P. aeruginosa. Accordingly, it can be concluded that these Rhus javanica L fruit extracts have the potential for antimicrobial materials for the cosmetic industry.

• Food Science and Preservation
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• v.23 no.3
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• pp.432-437
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• 2016

The objective of this research was to investigate the antioxidant and antimicrobial activities of Jeok Hasuo (Polygonum multiflorum Thunb., PM) and Baek Hasuo (Cynanchi wilfordii Radix, CW) root extracts. Total phenolic contents of PM and CW root extracts were determined and the antioxidant activities of the root extracts were determined by scavenging activity of diphenylpicrylhydrazyl (DPPH) radicals. The antimicrobial activities against Staphylococcus aureus and Propionibacterium acnes were determined and expressed as the minimum inhibitory concentration (MIC). The disc diffusion method was also used to determine the zone of inhibition. The butanol extracts of PM and CW roots exhibited greater total phenolic contents (1,212.6 and 1,454.5 mg/g GAE, respectively) than those of ethanol and water extracts. The ethanol (89.0%) and butanol extracts (88.9%) of PM exhibited significantly greater DPPH radical scavenging activities than that of water extracts (73.1%) (p<0.05). Only ethanol extract exhibited an MIC of 0.8 mg/mL against both bacteria. Zones of inhibition started to form when the concentration of extract was greater than 5 mg/disc. The diameters of the zone of inhibition of PM and CW were measured to be 8.9 and 9.2 mm against S. aureus and P. acnes, respectively, exhibiting the greatest antimicrobial activities among the extracts. This research demonstrated that the PM and CW root extracts possessed not only antioxidant activity but also strong antimicrobial activity against skin-related bacteria.

• Journal of Biosystems Engineering
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• v.39 no.2
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• pp.69-75
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• 2014

Purpose: This paper is aimed at analyzing the heating performance of the vertical closed loop type Geothermal Heat Pump System (GHPS) distributing the farm site and providing basic data of the GHPS. Method: Seedling greenhouse heating was made from October 2012 to May 2013. The seedling greenhouse was divided into 4 sectors (A, B, C and D zone, total $3,300m^2$) with different temperatures. It was heated from 5PM to 8AM, and during the night the greenhouse was covered by non-woven fabric thermal curtains along the upper 2m of the greenhouse for temperature maintenance. In order to analyze the heating performance of the GHPS, power consumption and operating time of the GHPS, inlet and outlet water temperature of the condenser, temperatures of each zone of the greenhouse, and ambient temperature were measured. Results: When operating only one heat pump unit, heat generated in the condenser decreased as the experiment progressed and power consumption increased correspondingly. However, the heating coefficient of performance decreased from 3.3 to 2.0 rapidly. Also, when operating two heat pump units, heat generated in the condenser decreased and power consumption increased. Heating coefficient of performance decreased from 4.5 to 3.7 rapidly. When the set temperature of the greenhouse was $13.7{\sim}20.1^{\circ}C$ and minimum ambient temperature was $-20.8{\sim}4.8^{\circ}C$, the annually accumulated heat and power consumption were 520,623 kW, 142,304 kW, respectively. Conclusion: When the set temperature of the greenhouse was $13.7{\sim}20.1^{\circ}C$ and the minimum ambient temperature was $20.8{\sim}4.8^{\circ}C$, the annually accumulated heat and power consumption were 520,623 kW, 142,304 kW, respectively. When operating only one heat pump unit, the heating COP was 2.0~3.3, and when operating 2 heat pump units, it was 3.7~4.5. If several heat pumps are installed in one GHPS, it is suggested that all heat pumps be operated except in special cases. Because the scale of the water pumps are set to the scale of when all heat pump units are operating, if even one unit is not operating, the power consumption will increase. That becomes the cause of COP decrease.

• Journal of the Korea Society of Computer and Information
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• v.20 no.7
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• pp.33-40
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• 2015

The time slot assignment problem (TSAP) or Satellite Communications scheduling problem (SCSP) for a satellite performs $n{\times}n$ ground station data traffic switching has been known NP-hard problem. This paper suggests $O(n^2)$ time complexity algorithm for TSAP of a satellite that performs $n^2{\times}n^2$ ground station data traffic switching. This problem is more difficult than $n{\times}n$ TSAP as NP-hard problem. Firstly, we compute the average traffic for n-transponder's basic coverage zone and applies ground station exchange method that swap the ground stations until all of the transponders have a average value as possible. Nextly, we transform the D matrix to $D_{LB}$ traffic matrix that sum of rows and columns all of transponders have LB. Finally, we select the maximum traffic of row and column in $D_{LB}$, then decide the duration of kth switch mode to minimum traffic from selected values. The proposed algorithm can be get the optimal solution for experimental data.

• Korean Journal of Plant Resources
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• v.30 no.3
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• pp.311-317
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• 2017

This study was conducted with the aim of evaluating the antibiotic effects of leaves, stems, and roots in yacon (Smallanthus sonchifolius). Antibacterial activity of leaf extract by disk diffusion method with Bacillus subtilis and Escherichia coli respectively showed 13.3 and 13.75mm diameters of clear zone. There was no significant difference between the stems and leaves. The minimum inhibitory concentration of leaves' heating and agitation extraction showed a restrain of strain at 1mg/ml, but the stems and root extract did not appear. Yacon is a functional antibacterial material, and methanol extraction is more effective than water. This research was to investigate the growth stage of collection has the most effective antibacterial effects. It has collected yacon's leaves from June to October, which is an appropriate time for collection right before reaping. Yacon leaf has antibacterial effects on Bacillus subtilis, Escherichia coli, Enterococcus faecium, and Salmonella enteritifis. There were no significant differences by the growth stage of collection. Leaves collected in July are high in phenol which helps in sulfating activity works well considering the high scavenging capability of DPPH. Leaves collected in September are high in total flavonoid.

• The Korea Journal of Herbology
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• v.25 no.2
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• pp.11-19
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• 2010

Objective : I want to examine the antimicrobial activity of Samhwangsasimtang against pseudomonas aeruginosa 38 isolated from an acne patient. Method : Antimicrobial activity was assayed through the hot water extract from Samhwangsasimtang against pseudomonas aeruginosa 38 isolated from an acne patient. Result : The size of inhibition zone of Samhwangsasimtang extract was $12.6\;{\pm}\;0.04\;mm$. The optimal pH and temperature for the growth of isolated pseudomonas aeruginosa 38 were 6.0 and $37^{\circ}C$, respectively. The minimum inhibitory concentration of Samhwangsasimtang extract was $10\;{\pm}\;0.06\;{\mu\ell}$ and the antimicrobial activity of Samhwangsasimtang extract was not destroyed by the heat ($121^{\circ}C$ for 15 min) and not affected by pH. Conclusion : Reviewing this experimental result, it appeared that Samhwangsasimtang had efficacy against pseudomonas aeruginosa 38 isolated from an acne patient.