• 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.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.38-42
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• 2004

A pilot-scale experiment for the treatment of red tide in the enclosure was done in sea area of Shandong Province, P. R. China on Aug. 25, 2002. With the method of strong dielectric barrier discharge in microgap, $O_2$in air and $H_2O$ in seawater are ionized and dissociated into large numbers of OHㆍradicals, and then dissolved into a part of seawater to form OHㆍsolution of high concentration. With OH' concentration of 0.68mg/L, the kill efficiencies of 29 kinds of red tide organisms such as Chaetoceros lorenzianus and so on reached 99.89%, in which the kill efficiencies of bacterium and vibrio were 100%, and that of Gonyaulax cysts and Prei. Cysts were up to 100%. At the same time, the content of chlorophyll-a was decreased into the lowest limit of test. DO saturation of seawater was greatly increased to 100% because the residual OHㆍradical was decomposed into $H_2O$ and $O_2$after 20 minutes, Therefore the treatment of red tide using OHㆍradicals is a kind of advanced oxidation technology, which realizes zero pollution, zero emission and zero residual in the process of the production of OHㆍradicals and the treatment of red tide.

• 한국인터넷방송통신학회논문지
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• 제24권2호
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• pp.51-57
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• 2024

추적 레이다 시스템은 대양에서 운용 중인 함정 표적에 대하여 실시간으로 표적을 탐색, 탐지하여 추적하는 펄스방식의 추적 시스템이다. 함정에서는 추적 레이다를 혼란 또는 기만하기 위한 소프트 킬 동작을 통하여 스스로를 방어한 다. 소프트 킬 동작에는 수동적으로 동작하는 채프 등이 있고 능동적으로 동작하는 잡음 재밍 등 여러 동작들이 있다. 본 논문에서는 전자전에 대한 기본적인 개념을 이해하고 함정에서 운용중인 다양한 기만체계에 대하여 설명한다. 또한 각각의 기만체계를 대응하기 위한 레이다 시스템 설계에 대하여 설명한다.

• Parasites, Hosts and Diseases
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• 제54권1호
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• pp.103-107
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• 2016

The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at $25^{\circ}C$ in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely.

• 약학회지
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• 제47권6호
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• pp.365-368
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• 2003

The bactericidal activities of DW286, a new fluoroquinolone were investigated by comparing the minimal bactericidal concentrations (MBCs) and the time-kill curve of it against some Gram-positive and Gram-negative bacterial strains. The MBCs of DW286 for the strains tested were either equal to or two-fold higher than the MICs, as were observed for the other fluoroquinolones. And DW286 exhibited rapid killing curves against the strains. Accordingly, it could be said that DW286 has bactericidal activity comparable to other fluoroquinolones.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.7176-7181
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• 2015

본 논문은 방초, 방림, 로드킬 등이 적용된 고기능 가드레일 지주에 태양광 모듈을 부착하여 자체 전력을 생산하고 USN을 이용하여 야생동물의 출현과 자동차 도로의 상황을 통합 관제 및 상시 감시할 수 있는 시스템에 관한 것이다. 전체 시스템은 태양광 발전 모듈, 감지 센서부(초전형), 제어부(동작 선택부 및 동작 센서부), USN시스템, DB(응향 및 섬광), 음향 및 섬광 출력부, 로드킬 방지 및 자동차 안전유도 제어 시스템으로 구성된다. 따라서, 도로환경의 개선과 로드킬을 방지하여 동물들을 보호할 수 있고 자동차를 안전하게 유도하며 신재생에너지와 IT융합 기술이 접목된 USN을 이용한 다목적 가드레일의 원격제어 및 모니터링 시스템에 관한 연구이다. USN을 이용한 원격제어 및 모니터링 시스템의 실험결과 무인 감지 시스템의 동작시간은 5.1 ms 이내, 소비전류는 0.328 mA이며 원격제어 시스템의 데이터 전송 속도는 250 kbps, 소비전류는 0.283 mA로 구현됨을 확인할 수 있었다.

• 미생물학회지
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• 제54권3호
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• pp.272-279
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• 2018

본 연구는 여드름을 유발하는 세균인 Propionibacterium acnes에 대해 다양한 토양에서 분리된 세균 균주들의 항균효과를 조사하기 위해 수행되었다. 수백 개의 분리 세균균주 중 Paenibacillus elgii DS381과 Paenibacillus elgii DS1515, Burkhoderia gladioli DS518, Streptomyces lienomycini DS620는 2가지 균주의 P. acnes에 대해 높은 항균활성을 나타내었다. 이 분리균주들은 agar well diffusion test에서 15.5~34.3 mm 직경의 저해대를 형성하였으며, 특히 DS620는 가장 큰 저해대 직경(28.3~34.3 mm)을 나타내었다. 분리 균주가 생성하는 항균 물질은 DS381과 DS1515 균주의 경우lipopeptide (pelgipeptin, paenipeptin), DS518은 protease, 그리고 DS620은 anthracycline 인 것으로 추정되며, 이들 모두 P. acnes에 대해매우낮은 최소저해농도를 나타내었다[DS381와 DS1515 (0.078 mg/ml), DS518 (0.312 mg/ml), DS620 (0.000078 mg/ml)]. P. acnes를 대상으로 한 time-kill assay에서는 네 균주의 항균물질이 모두 24시간 이내에 P. acnes를 완전히 사멸시켰다. 이 결과는 네 가지 항균활성 균주들이 분비하는 항균물질들이 여드름을 유발하는 P. acnes에 대하여 효율적인 치료 소재로 사용될 수 있는 가능성을 보여준다.

• 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.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권3호
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• pp.127-141
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• 2015

Silver-based systems activated by low intensity direct current continue to be investigated as an alternative antimicrobial for infection prophylaxis and treatment. However there has been limited research on the quantitative characterization of the antimicrobial efficacy of such systems. The objective of this study was to develop a semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model providing the quantitative relationship between the critical system parameters and the degree of antimicrobial efficacy. First, time-kill curves were experimentally established for a strain of Staphylococcus aureus in a nutrientrich fluid environment over 48 hours. Based on these curves, a modified PK/PD model was developed with two components: a growing silver-susceptible bacterial population and a depreciating bactericidal process. The test of goodness-of-fit showed that the model was robust and had good predictability ($R^2>0.7$). The model demonstrated that the current intensity was positively correlated to the initial killing rate and the bactericidal fatigue rate of the system while the anode surface area was negatively correlated to the fatigue rate. The model also allowed the determination of the effective range of these two parameters within which the system has significant antimicrobial efficacy. In conclusion, the modified PK/PD model successfully described bacterial growth and killing kinetics when the bacteria were exposed to the electrically activated silver-titanium implant system. This modeling approach as well as the model itself can also potentially contribute to the development of optimal design strategies for other similar antimicrobial systems.

• 미생물학회지
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• 제55권1호
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• pp.46-51
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• 2019

이 연구에서는 유칼립투스, 유카와 차나무의 ethanol 추출물의 수지를 이용한 분획 혼합물에 대한 항균활성을 평가하였는데 여러 인간 피부 상재균에 낮은 최소저해농도(0.24~3.32 mg/ml)를 나타내었고 항생제 triclosan과 ampicillin보다 우수한 활성을 나타내었다. Time kill assay에서 식물 추출분획 혼합물은 4시간 이내에 미생물 균주의 개체수를 92% 이상 감소시켰고, 모든 미생물 균주의 뉴클레오티드를 상당량 유출시켰으며, 항균 효과는 이가 양이온($Mg^{2+}$과 $Ca^{2+}$)에 영향을 받지 않았다. 이러한 결과는 Eucalyptus sp., Yucca sp., 및 tea tree의 ethanol 추출물의 수지분획 혼합물이 중요한 인간 피부 상재균을 억제하는 효율적인 화장품 방부제로 이용될 수 있음을 시사한다.