• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1581-1586
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• 2012

In this paper, a novel resonator using ring type DGS is proposed for improvement of phase noise characteristics that is weak point of oscillator using planar type microstrip line resonator, and oscillator for 5.8GHz band is designed using proposed DGS resonator. The ring type DGS resonator is composed of DGS cell etched on ground plane under $50{\Omega}$ microstrip line. At the fundamental frequency of 5.8GHz, 7.6dBm output power and -82.7 dBc@100kHz phase noise have been measured for oscillator with ring type DGS resonator. The phase noise characteristics of oscillator is improved about 9.5dB compared to one using the general ${\lambda}/4$ microstrip resonator. Because it is possible that varactor diode or lumped capacitor is placed on the gaps of ring type DGS, resonant frequency can be controlled by bias voltage. We can design voltage controlled oscillator using proposed ring type DGS resonator. Thus, due to its simple fabrication process and planar type, it is expected that the technique in this paper can be widely used for low phase noise oscillators for both MIC and MMIC applications.

• Advances in Traditional Medicine
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• v.4 no.4
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• pp.261-266
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• 2004

Wound swabs and pus samples were collected from diabetic foot ulcers, and control pus samples from non-diabetic cases. In 144 diabetic cases screened, Pseudomonas aeruginosa was isolated from 78 cases, in which 10.59% of the isolates were multidrug resistant (MDR), whereas the 60 control cases were not MDR. The isolated bacteria were decreasingly resistant to 6 clinically administrated antimicrobics such as ceftazidime, gentamicin, ciprofloxacin, tobramycin, piperacillin and amikacin. Therefore, it is demanded that new and more effective antimicrobials of phytochemical origins are sought after. Among 11 isoflavones (YS11-YS21) isolated from Sophora and Euchresta (Leguminosae; pea plant family), 2 (YS19 and YS21) prominently exhibited the high antibacterial activity both in vitro and in vivo. By the preliminary results, the object of this paper is to evaluate the in vitro antibacterial effect of YS19 and YS21 on the clinically isolated bactera of Ps. Aeruginosa in hospitals. All the isolates were sensitive to YS19 and YS21 and for both, minimum inhibitory concentration (MIC) values ranged from $2\;to\;50\;{\mu}g/mL$. The $MIC_{90}$ values of YS19 and YS21 were $50\;{\mu}g/mL$. It is suggested that these isoflavones might consist a basis phytochemical prevention and therapy for diabetic foot infections caused by pseudomonads.

• Journal of Pharmacopuncture
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• v.10 no.2 s.23
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• pp.19-23
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• 2007

Objectives : This experimental study was performed to investigate the continuous anti-bacterial potency of Sean-tang on cultivation of Staphylococcus species(S. aureus, S. epidermidis) that induce eye disease. Methods : Minimal inhibitory concentration(MIC) was measured by dropping to 50${\mu}$l diluted Sean-tang(100%, 10%,1%, 0.1%) on S. aureus, S. epidermidis that were cultivated from 2 to 6 days. 1. Anti-bacterial potency was measured by the size of inhibition zone with change of volume(20${\mu}$l, 30${\mu}$l, 40${\mu}$l, 50${\mu}$l). Results : 1. Anti-bacterial potency of Sean-tang on S. aureus was appeared in 100% and increased on 6 days. Anti-bacterial potency with change of volume was increased in propotion to increase volume. Anti-bacterial potency of Sean-tang on S. aureus was appeared continuous. 2. Anti-bacterial potency of S. epidermidis was appeared in 100%, 10%, 1% on 2 days and in100%, 10% on 6 days. In 100% Sean-tang, Anti-bacterial potency of 6 days was increased, in 10%, 1%, Anti-bacterial potency of 2 days was increased. Anti-bacterial potency with change of volume was increased inpropotion to increase volume and increased on 6 days, but bacteria was increased. Anti-bacterial potency Sean-tang on S. epidermidis wasn't appeared continuous. Conclusions : Anti-bacterial potency of Sean-tang on cultivation of S. aureus was showed continuous, but on cultivation of S. epidermidis was not showed continuous.

• Journal of Pharmacopuncture
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• v.10 no.2 s.23
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• pp.87-91
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• 2007

Objectives : This experimental study was performed to investigate the continuous anti-bacterial potency of Jinpi-san on cultivation of Staphylococcus species(S. aureus, S. epidermidis) that induce eye disease. Methods : Minimal inhibitory concentration(MIC) was measured by dropping to 50${\mu}$l diluted Jinpi-san(100%, 10%, 1%, 0.1%) on S. aureus, S. epidermidis that were cultivated from 2 to 6 days. Anti-bacterial potency was measured by the size of inhibition zone with change of volume(20${\mu}$l, 30${\mu}$l, 40${\mu}$l, 50${\mu}$l). Results : 1. Anti-bacterial potency of Jinpi-san on S. aureus was appeared in 100% and increased on 6 days. Anti-bacterial potency with change of volume was increased in propotion to increase volume. Anti-bacterial potency of Jinpi-san on S. aureus was appeared continuous. 2. Anti-bacterial potency of Jinpi-san on S. epidermidis was appeared in 100%, 10%, 1% on 2 days and in 100%, 10% on 6 days. In 100% Jinpi-san, Anti-bacterial potency of 6 days was increased, in 10%, Anti-bacterial potency of 2 days was increased, in 1%, Anti-bacterial potency of 6 days was disappear. Anti-bacterial potency with change of volume was increased in propotion to increase volume except for 20${\mu}$l of 6days and increased on 6 days, but bacteria was increased. Anti-bacterial potency of Jinpi-san on S. epidermidis wasn't appeared continuous. Conclusions : Anti-bacterial potency of Jinpi-san on cultivation of S. aureus was showed continuous, but on cultivation of S. epidermidis was not showed continuous.

• Korean Journal of Microbiology
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• v.40 no.1
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• pp.1-6
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• 2004

Tetracycline resistant bacterial strains were isolated from 10 batches of Kimchi among 50 batches collected in Taegu restrict. The MIC of tetracycline ranged between 25 and> 100 ㎖/l. Total genomic DNA preparation from all 10 tetracycline resistant lactic acid bacterial isolates were subjected to PCR amplification with class-specific primers for tet(M) and tet(O). In only one isolate, HJ9, tet(M) was detected. By Southern blotting and hybridization with a tet(M)-specific probe, the tet(M) gene of HJ9 isolate could be localized on a plasmid. The partial nucleotide sequence and deduced amino acid sequence of tet(M) of HJ9 showed 90-99% and 94-100% homology to those of Gram positive bacteria, respectively. With sequencing of 16S rRNA, HJ9 isolate from Kimchi was identified as Lactobacillus sakei. From these results, Kimchi can be considered potential vehicle for the spread of antibiotic-resistant lactic acid bacteria along the food chain to the consumer.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.4
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• pp.909-913
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• 2006

The antioxidative activity was observed in the ethyl acetate extract $(IC_{50},\;119{\pm}0.16\;{\mu}g/mL)$ from Pueraria thunbergiana. The DPPH radical scavenging effect of this extract was comparable with that of synthetic antioxdant, BHA $(IC_{50},\;88.39{\pm}1.1\;{\mu}g/mL){\times}\;10^{-3}\;{\mu}M$. Pueraria thunbergiana extracts against microorganisms were evaluated in terms of the minimum inhibitory concentrations (MIC). In general, C. albicans was stronger antimicrobial activity than the other microorganisms. in vitro the antitoxic activity of extracts of Pueraria thunbergiana on NIH 373 fibroblasts was evaluated by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) method. Generally, detoxification effect by the extracts of Pueraria thunbergiana increased in proportion to the concentrations. When $10\;{\mu}g/mL$ of the hexane extract of Pueraria thunbergiana was treated it showed the highest antitoxic effects (p<0.01). These results suggest that the crude extract of P. thunbergiana has a potential therapeutic activity.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.357-362
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• 2021

In this study, to investigate the anticariogenic effect of red ginseng, the antibacterial effect, cell adherence and biofilm formation inhibitory effect of n-hexane extract of red ginseng marc (HERGM) against Streptococcus mutans, the causative bacteria of caries, were measured. The growth of S. mutans was inhibited in proportion to the concentration of HERGM, and was hardly observed at a concentration above 125 ㎍/mL (MIC =125 ㎍/mL). It was found that HERGM acts on the cell membrane and the nucleic acid component of the cell was leaked. In addition, HERGM inhibited the adherence and biofilm formation of S. mutans by more than 90% at a concentration of 125 ㎍/mL. GTase activity was completely inhibited at a concentration of 50 ㎍/mL of HERGM. In conclusion, it was found that HERGM commonly inhibited the growth and biofilm formation of S. mutans.

• Journal of the FoodService Safety
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• v.1 no.1
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• pp.27-35
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• 2020

Salt is a common seasoning agent used in various processed foods, especially in kimchi and salted seafood (jeotgal). This study was conducted to investigate the efficacy of salt with antimicrobial substances (acetic acid, garlic extract, carvacrol, nisin, thymol, and their combination (acetic acid+nisin+thymol)) on improvement of antibacterial effects of salt against foodborne pathogens. Salt (10%) was prepared using six different types of 0.2% natural antimicrobial substances. The antibacterial effect of salt combined with natural antimicrobial substances was evaluated against foodborne pathogens using the broth micro-dilution method and growth curve plotted using absorbance measurements. For the five foodborne pathogens, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of salt without antimicrobial substances as control were in the range of 24~>50,000 ㎍/mL and >50,000 ㎍/mL, respectively. Salt with nisin, thymol, or garlic extract showed strong inhibitory effects and their MIC against L. monocytogenes were 49, 12,500, and 24 ㎍/mL, respectively. In particular, salt with nisin showed inhibitory activities against Gram-positive bacteria. However, all the antimicrobial substances were less effective against Gram-negative bacteria such as E. coli O157:H7 and S. Typhimurium than Gram-positive bacteria. These results could be used for the development of salt with natural antimicrobial substances especially targeted against L. monocytogenes. This would enable the lowering of saline concentration while improving the storability of food.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.54-63
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• 2019

Rubus coreanus Miquel (RCM), also known as Korean blackberry or bokbunja, is used as a South Korean traditional medicine to treat acne and inflammatory skin conditions. The antimicrobial activity of RCM root and its active compounds remain unclear. In this study, we prepared a 50% ethanol fraction, ethyl acetate fraction, and acid-treated ethyl acetate fraction (aglycone fraction) of RCM root, and evaluated antibacterial activities against the skin pathogens Staphylococcus aureus, Pseudomonas acnes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. In a paper disc assay, all fractions of RCM root showed antimicrobial activities against the five skin pathogens. The ethyl acetate fraction displayed 6-, 12-, and 2-fold higher minimal inhibitory concentration (MIC) than the 50% ethanol fraction against S. aureus, E. coli, and P. acnes, respectively. The aglycone fraction displayed 2-fold higher MIC than methyl paraben against P. acnes, S. aureus, E. coli, and P. aeruginosa. The ethyl acetate fraction displayed a minimal bactericidal concentration (MBC) similar to that of methyl paraben, and the aglycone fraction showed 2- to 4-fold higher MBCs than those of methyl paraben. In particular, the ethyl acetate fraction was not cytotoxic and showed thermal stability after incubation at high temperatures ($60-121^{\circ}C$). Finally, the ethyl acetate fraction was separated and four components were identified: procyanidin C, propelagonidin dimer, ellagic acid, and methyl ellagic acid acetyl pentose. The compounds showed high antibacterial activities. These results suggest that RCM root is potentially applicable as a natural preservative in cosmetics.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1179-1188
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• 2023

Escherichia coli, particularly multidrug-resistant (MDR) strains, is a serious cause of healthcare-associated infections. Development of novel antimicrobial agents or restoration of drug efficiency is required to treat MDR bacteria, and the use of natural products to solve this problem is promising. We investigated the antimicrobial activity of dried green coffee (DGC) beans, coffee pulp (CP), and arabica leaf (AL) crude extracts against 28 isolated MDR E. coli strains and restoration of ampicillin (AMP) efficiency with a combination test. DGC, CP, and AL extracts were effective against all 28 strains, with a minimum inhibitory concentration (MIC) of 12.5-50 mg/ml and minimum bactericidal concentration of 25-100 mg/ml. The CP-AMP combination was more effective than CP or AMP alone, with a fractional inhibitory concentration index value of 0.01. In the combination, the MIC of CP was 0.2 mg/ml (compared to 25 mg/ml of CP alone) and that of AMP was 0.1 mg/ml (compared to 50 mg/ml of AMP alone), or a 125-fold and 500-fold reduction, respectively, against 13-drug resistant MDR E. coli strains. Time-kill kinetics showed that the bactericidal effect of the CP-AMP combination occurred within 3 h through disruption of membrane permeability and biofilm eradication, as verified by scanning electron microscopy. This is the first report indicating that CP-AMP combination therapy could be employed to treat MDR E. coli by repurposing AMP.