• 지구물리와물리탐사
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• 제10권3호
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• pp.191-202
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• 2007

한반도 남부지역의 세부적인 지진파 감쇠특성 규명을 위해, 기존에는 적용이 불가능하였던 Q 토모그래피 역산을 위한 사전 수치검증 연구를 수행하였다. 특히 강지진동모사를 위해 일반적으로 사용되고 있는 추계학적 점지진원 지진동 모델(stochastic point-source ground-motion model; Boore, 2003)에서 사용되는 Q 값에 대한 2차원(2D; 2 Dimensional) 토모그래피 역산을 시도함으로써 역산 결과가 강지진동모사에 직접 활용될 수 있도록 하였다. 수치검증 방법으로는 Q 토모그래피 checkerboard 시험방법이 사용되었는데, 이를 위해 광역 단일 Q 모델의 추계학적 지진동모델 파라미터 역산결과의 지진원과 부지효과 모델 파라미터 값을 이용해서 관측자료와 지진규모-거리-주파수-오차 분포가 동일한 스펙트럼 합성자료를 생성하였다. 수치검증을 위한 Q 블록 격자의 총 개수는 75개(내륙지역=69개(약 $35{\times}44km^2$의 격자크기); 해양지역=6개)로 설정하였으며, $Q_0f^{\eta}$ 함수형태의 Q 블록 값은 $Q_0$=100, 500, ${\eta}=0.0{\sim}1.0$의 분포를 갖도록 하고, 파선의 깊이는 별도로 고려하지 않았다. 스펙트럼 합성자료 생성에 이용된 모델파라미터의 정해와 모델파라미터의 역산결과를 비교하기 위한 checkerboard 수치검증은 3단계에 걸쳐 수행되었는데, 1단계는 블록별 Q의 초기값 추정 단계이며, 2단계는 관측소별 부지증폭함수를 추정하는 단계, 마지막 3단계에서는 최종적인 Q를 도출하는 단계이다. 관측소별 부지증폭함수의 초기 추정값으로는 기 분류된 관측소 등급에 대한 평균 부지증폭함수(연관희, 서정희, 2007)가 사용되었으며, 3단계의 checkerboard 수치검증 결과 최종적으로 추정된 부지효과 모델에는 오차가 발생하였으나 블록별 Q의 정해는 만족할 정도로 추정할 수 있었다.

• 한국음향학회지
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• 제18권1호
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• pp.67-71
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• 1999

본 논문에서는 회로의 테스트 시간과 비용을 절감할 수 있는 BIST(Built-In Self Test)기법을 이용하여 메모리 테스트 알고리즘을 칩내에서 수행하는 회로를 설계하였다. 메모리 테스트에 사용되는 MSCAN, Marching, Checkerboard알고리즘을 수행하는 회로를 구현하기 위해 BIST회로에서 요구되는 구조를 파악하고 VHDL을 이용하여 각 블록별로 기술하였다. 그리고 CAD tool을 이용하여 각 블록에 대한 동작을 검증하고 회로합성기로써 각 알고리즘에 대한 BIST 회로를 추출하였다. 추출된 회로는 전체 메모리에 대해 무시할 정도의 오버헤드를 갖는다.

• Journal of Microbiology
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• 제45권5호
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• pp.473-477
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• 2007

The in vitro antibacterial activity against antibiotic-resistant Propionibacterium acnes of kaempferol isolated from the Impatiens balsamina alone and in combination with erythromycin or clindamycin antibiotics was investigated. The antibiotic combination effect against antibiotic-resistant P. acnes was studied by checkerboard test. Kaempferol and quercetin demonstrated antibacterial activities against P. acnes. Minimum inhibitory concentrations (MICs) for both compounds were ${\leq}32\;{\mu}g/ml\;and\;{\leq}64{\mu}g/ml$ for clindamycin-sensitive and -resistant P. acnes, respectively. The four combination formulations (kaempferol and either erythromycin or clindamycin; quercetin and either erythromycin or clindamycin) exhibited a synergic inhibition of P. acnes growth. The combination of kaempferol with quercetin showed an indifferent effect. The combination of clindamycin with kaempferol or quercetin showed a greater synergic effect than that of erythromycin with kaempferol or quercetin. Thus, these combinations demonstrated the potential to treat acne.

• 한방재활의학과학회지
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• 제28권2호
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• pp.21-35
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• 2018

Objectives The objective of this study is to determine the antimicrobial effect of Daehwanggyeonu-san(Dahwangqianniu-san,DGE) and synergistic effects with antibiotics oxacillin, ampicillin, and gentamicin against Methicillin-Resistant Staphylococcus aureus(MRSA). Methods The antibacterial activity of DGE extract was evaluated againest MRSA strains by using the Disc diffusion method, broth microdilution method(minimal inhibitory concentration; MIC), checkerboard dilution test. The checkerboard dilution test was used to examined synergetic effect of oxacillin, ampicillin, gentamicin, ciprofloxacin with DGE extract. Results DGE showed antimicrobial activity against MRSA with an MIC value of $125{\sim}250{\mu}g/mL$. In the checkerboard test, the interation of DGE with all tested antibiotics produced almost synergy or partial synergy against MRSA. Conclusions This study shows that DGE reduced the MICs of several antibiotics tested, and a remarkable antibacterial effect of DGE, with membrane permeability enhancers and ATP synthase inhibitors. This study can be a valuable source for the development of a new drug with low MRSA resistance.

• 한국자원식물학회지
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• 제31권6호
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• pp.719-724
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• 2018

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for a number of infections in humans that are difficult to treat, and as a result, is a substantial contributor to morbidity and mortality. In the present study, in search of natural products capable of inhibiting this multidrug-resistant bacterium, we investigated the antimicrobial activity of Lysimachia clethroides Duby root. The antibacterial activities of EtOH extract of Lysimachia clethroides Duby root and its n-hexane, EtOAc, n-BuOH and water fractions were evaluated against 15 strains of methicillin-resistant staphylococcus aureus (MRSA) and 1 standard methicillin-susceptible S. aureus (MSSA) strain by using the minimal inhibitory concentrations (MICs) assay, colorimetric assay using MTT test, checkerboard dilution test. Antimicrobial activity of n-hexane fraction of Lysimachia clethroides Duby root was remarkable. Against the 16 strains, the minimum inhibitory concentrations (MICs) were in the range of $31.25-62.5{\mu}g/ml$ and FICI values for n-hexane fraction of Lysimachia clethroides Duby root+AM and n-hexane fraction of Lysimachia clethroides Duby root+OX were checkerboard method performed using the MRSA, MSSA and one clinical isolate strains via MICI 0.12-1 and 0.25-0.75, showing the increase of synergistic effect. When combined together, these antibiotic effects were dramatically increased. These effective combinations could be new promising agents in the management of MRSA.

• 한방재활의학과학회지
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• 제25권2호
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• pp.1-13
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• 2015

Objectives Methicillin-Resistant Staphylococcus aureus (MRSA) is a human pathogen and a major cause of hospital-acquired infections. New antibacterial agents that have not been compromised by bacterial resistance are needed to treat MRSA-related infections. In this study, we investigated the antimicrobial activity ofethanol extract of Haedokgeumhwa-san (HGH) which prescription is composed of korean medicine against MRSA. Methods The antibacterial activity of HGH extract was evaluated against MRSA strains by using the Disc diffusion method, broth microdilution method (minimal inhibitory concentration; MIC), checkerboard dilution test, and time-kill test; its mechanism of action was investigated by bacteriolysis, detergent or ATPase inhibitors. The checkerboard dilution test was used to examined synergistic effect of ampicillin, oxacillin, ciprofloxacin, vancomycin, gentamicin and norfloxacin in combination with HGH ethanol extract. A time-kill assay was performed a survival curve which was obtained by plotting viable colony counts depending on time on bacterial growth. Results The minimum inhibitory concentration (MIC) of ethanol extract (HGH) ranged from 1,000 to $2,000{\mu}g/mL$ against all the tested bacterial strains, respectively. We are able to confirm that HGH extract has potentially strong antibacterial activity. In the checkerboard dilution test, fractional inhibitory concentration index of HGH in combination with antibiotics indicated synergy or partial synergism against S. aureus. A time-kill study showed that the growth of the tested bacteria was considerably inhibited after 8 hr of treatment with the combination of HGH with selected antibiotics. For measurement of cell membrane permeability, HGH $250{\sim}1,000{\mu}g/mL$ along with concentration of Triton X-100 (TX) and Tris-(hydroxymethyl) aminomethane (Tris) were used. In the other hand, N,N-dicyclohexylcarbodimide (DCCD) and Sodium azide ($NaN_3$) was used as an inhibitor of ATPase. TX, Tris, DCCD and $NaN_3$ cooperation against S. aureus showed synergistic action. Accordingly, antimicrobial activity of HGH was affected by cell membrane and inhibitor of ATPase. Conclusions These results suggest that Haedokgeumhwa-san extract has antibacterial activity, and that HGH extract offers a potential as a natural antibiotic against MRSA.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.82-87
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• 2010

Biotransformation is often used to improve chemical activity. We evaluated the antimicrobial activity of rhapontigeuin, converted from rhapontin after treatment with Pectinex. Rhapontigenin showed 4-16 times higher antimicrobial activity than rhapontin. The activity was higher against Gram-positive strains than Gram-negative strains. Minimum inhibitory concentrations (MICs) of rhapontigenin, retinol, and five antibiotics were determined by the microbroth dilution method for antibiotic-sensitive and -resistant Propionibacterium acnes. We also investigated the in vitro antibacterial activity of rhapontigenin in combination with antibiotic against antibiotic-resistant P. acnes. The antibiotic combination effect against resistant P. acnes was studied by the checkerboard method. The combination formulations (rhapontigenin and clindamycin, retinol and clindamycin) showed synergistic effects on the inhibition of the growth of clindamycin-resistant P. acnes. It is predictable that the combination of antibiotics with rhapontigenin is helpful to treat acne caused by antibiotic-resistant P. acnes. The antibacterial activity of rhapontigenin was enhanced by biotransformation.

• 대한본초학회지
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• 제30권5호
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• pp.15-21
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• 2015

Objectives : Methicillin-resistantStaphylococcus aureus(MRSA) is a human pathogen. New antibacterial agents are needed to treat MRSA-related infections. This study investigated the antibacterial activity of EtOH 70% extracts ofTonghyeonipal-dan(THD) which prescription is composed of oriental medicine against MRSA.Methods : The antibacterial activity of THD was evaluated against MRSA strains by using the Disc diffusion method, broth microdilution method, Checkerboard dilution test, and Time-kill test; its mechanism of action was investigated by bacteriolysis, detergent or ATPase inhibitors were used.Results : The minimum inhibitory concentration (MIC) of THD is 1,000~2,000 μg/mL against MRSA. In the checkerboard dilution test, fractional inhibitory concentration index (FICI) of THD in combination with antibiotics indicated synergy or partial synergism againstS. aureus. Furthermore, a time-kill assay showed that the growth of the tasted bacteria was considerably inhibited after 24 h of treatment with the combination of THD with selected antibiotics. For measurement of cell membrane permeability, THD 500 μg/mL along with concentration of Triton X-100 (TX) and Tris-(hydroxymethyl) aminomethane (TRIS) were used. In the other hand, N,N-dicyclohexylcarbodimide (DCCD) and Sodium azide (NaN3) were used as an inhibitor of ATPase. TX, TRIS, DCCD and NaN3 cooperation againstS. aureusshowed synergistic action.Conclusions : Accordingly, antimicrobial activity of THD was affected by cell membrane and inhibitor of ATPase were assessed. These results suggest that THD has antibacterial activity, and that THD extract offers great potential as a natural antibiotic against MRSA.

• 한방재활의학과학회지
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• 제30권1호
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• pp.31-45
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• 2020

Objectives In this study, we investigated the antimicrobial activity of a 70% ethanol extract of Maneung-hwan (MEH), which is prescribed by practitioners of oriental medicine for use against methicillin-resistant Staphylococcus aureus (MRSA). Methods The antibacterial activity of MEH against MRSA strains was evaluated using the disc diffusion method, broth microdilution method (minimal inhibitory concentration, MIC), checkerboard dilution test, and time-kill test. The mechanism of action of MEH was investigated by bacteriolysis using detergents or ATPase inhibitors Additionally, mRNA and protein expression were investigated by quantitative reverse transcription-polymerase chain reaction and western blot assay, respectively. Results The MIC of MEH was 25~1,600 ㎍/mL against all the tested bacterial strains. We showed that MEH extract exerts strong antibacterial activity. In the checkerboard dilution test, the fractional inhibitory concentration index of MEH in combination with antibiotics indicated synergism or partial synergism against S. aureus. The time-kill study indicated that the growth of the tested bacteria was considerably inhibited after a 24-h treatment with MEH and selected antibiotics. To measure the cell membrane permeability, MEH (3.9 ㎍/mL) was combined with Triton X-100 (TX) at various concentrations N,N-dicyclohexylcarbodimide (DCCD) was also tested as an ATPase inhibitor. TX and DCCD cooperation against S. aureus exhibited synergistic action. Accordingly, the antimicrobial activity of MEH in the context of cell membrane rupture and ATPase inhibition was assessed. Additionally, the expression of genes and proteins associated with resistance was reduced after exposing MRSA to MEH. Conclusions These results suggest that MEH possesses antibacterial activity and acts as a potential natural antibiotic against MRSA.

• Toxicological Research
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• 제13권1_2호
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• pp.111-116
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• 1997

In the present study, we investigated the neutralization activity of various antimicrobials against lipopolysaccharide (LPS) as well as interaction between two antimicrobials (enrofioxacin and coilstin) using checkerboard method. The neutralization activity of antimicrobials used in the test was assayed by means of LAL chromogenic test after reaction of LPS with colistin, enorfioxacin, ampicillin, polymyxin B, oxytetracycline, streptomycin, and erythromycin. As the results, the neutralization activity of coltstin and polymixin B had a more stronger than that of tested other antimicrobials. In bacterial culture broth, the best neutralization activity of the antibiotics was also shown to coltstin and polymixin B. Meanwhile, It was shown to have synergism between enorfloxacin and coltstin on the basts of FIC (fractional inhibition concentration). The FIC of enorfioxacin-colistin combinations was 0.50-1.03 to Staphylococcus aureus R-209, 1.03-1.06 to Salmonella typhimurium, 0.75-1.25 to Bordetella Bronchtseptica and 1.02-1.25 to E. coli K88ab. On the basts of the above results, the present study may be of clinical usefulness in the choice of an antibiotic therapy for severe sepsts in animals.