• 상하수도학회지
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• 제22권3호
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• pp.323-328
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• 2008

During the full-scale water treatment operation at "G" Water Treatment Plant in Seoul, we investigated changes in pore volume distribution and specific surface area of GAC with time. The pore volume of the used GAC decreased to the level below 0.6 cc/g while that of the brand new GAC was ranged 0.7~0.9 cc/g. The specific surface area of GAC pores changed within the range between $1100{\sim}1200m^2/g$ and $700{\sim}800m^2/g$. Bacteria attached to the surface of GAC shows a gradual increase ($0.4{\time}10^6{\sim}8.5{\time}10^6CFU/g$) under scanninig electron microscope (SEM). TOC removal was enhanced due to growth of the attached bacteria on GAC. It was found that TOC removal was closely related with physical parameters (pore volume, specific surface area) linearly under the investigated conditions. The used GAC need to be exchanged into new one or re-generated to remove organic matters (TOC) effectively from the finished drinking water.

• 상하수도학회지
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• 제8권3호
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• pp.19-25
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• 1994

In this research, characteristics of nitrification and denitrification using the microorganism attached on sponge and plates were examined. The denitrification and nitrification performance were investigated under the anaerobic and aerobic condition for about 2 months. Because the basins of denitrification and nitrification were connected in series, wastewater was flowed from denitrification basin to nitrification one. The 90% of influent flowrate was returned from nitrification basin to denitrification one. Most of organic material was removed in nitrification basin, wherease the only exact amount of organics required in denitrification process was removed in denitrification one. This experiment resulted in that heterotrophic bacteria existing in aerobic basin governed the removal efficiency of organic compounds. In case the influent BOD concentration into nitrification basin was 80mg/l, it did not affect to accumulation of nitrifying bacteria, the balance of heterotrophic bacteria was proved to be an important factor in nitrification/denitrification method such as anaerobic and aerobic cycling type.

• Journal of Microbiology
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• 제37권4호
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• pp.263-266
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• 1999

In examining bacterial growth on glass surfaces immersed in sea water, we found serious differences between enumeration methods. Therefore, we compared various methods and found sonication and direct count methods were superior to other methods. Since the direct count method was not suitable for long-term investigation, we chose the sonication method and confirmed that sonication periods 8 times for 30 seconds was optimal for the detachment of bacteria from glass surfaces.

• 상하수도학회지
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• 제19권2호
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• pp.181-192
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• 2005

This study evaluated the effect of factors influencing the initial biofilm formation in drinking water distribution pipe by running experiments using a $2^{4-1}$ fractional factorial experimental design with a replicate. Important variables used for assessing biofilm formation included BDOC(biodegradable dissolved organic carbon), viable heterotrophic bacteria present in drinking water, water temperature, and shear stress at two levels each. Based on the statistical analysis of biofilm levels measured as attached HPC(heterotrophic plate count) and community-level assay, the main factors that have significant effects on biofilm formation were found to be viable heterotrophic bacteria and BDOC. Water temperature only exhibited significant effect on the levels of attached HPC, while shear stress was not a significant factor under given conditions. Moreover, the statistical analysis revealed that interactions between the important variables were not statistically significant at a 0.05 significance level.

• 한국치위생학회지
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• 제4권2호
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• pp.255-263
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• 2004

One of the best way to prevent dental caries and periodontal disease is removing dental plaque. Toothbrushing is also one of the crucial ways to gel rid of dental plaque and improve dental hygiene. The purpose of th is study was to examine how many bacteria were attached to toothbrushes used by dental palque acidogenecity and related behaviors to toothbrush use. Subjects in this study were 30 college students in their twenties, on whom a survey was conducted to find out how they cleansed their toothbrushes, how long they cleaned toothbrushes after brushing, and how to keep them. And then dental palque acidogenecity by caries activity test was implemented and the number of bacteria attached to their toothbrushes was tested. The findings of the study were as follows : 1. Concerning correlations between dental palque acidogenecity and the number of remaining bacteria in the toothbrushes used by students, the number of bacteria was lower in the group of students with no caries activity than in the group with mild caries activity. 2. As for relations between the way of cleansing toothbrushes and the number of bacteria, there was no statistically significant gap between the group of students who wetted their toothbrushes with water and rubbed the heads of them and the group of students who just only wetted their toothbrushes with no further actions. 3. Regarding the relationship of toothbrush cleansing time to the number of bacteria, the number of bacteria was lower in the group of students who cleansed their toothbrushes for 15 seconds or more. 4. As to the influence of the number of toothbrush used by students, there was no significant difference between the group using just one toothbrush and the other group using two or more toothbrushes. 5. As for correlations between the way of keeping toothbrushes and the number of bacteria, no significant gap existed between the group thai kept their toothbrushes separately and the other that didn't.

• 대한환경공학회지
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• 제29권2호
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• pp.184-191
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• 2007

활성탄 공정에서 chloropicrin, DCAN, DBAN 및 TCAN과 같은 질소계 염소 소독부산물의 제거기작은 운전초기에는 흡착이 높은 비중을 차지하나 부착미생물의 활성이 중진되면서 부착미생물에 의한 생분해와 흡착에 의해 제거되었으며, 이들 물질들은 생분해능이 큰 물질들로 조사되었다. 입상활성탄 재질별 chloropicrin, DCAN, TCAN 및 DBAN의 제거 특성은 석탄계와 야자계 재질의 활성탄에서 제거율이 높았고, 목탄계는 상대적으로 낮은 제거능을 보였으며, 안트라사이트 biofilter에서 가장 낮은 제거능을 보였다. 활성탄 재질별 부착 미생물의 생체량과 활성도는 석탄계가 가장 높았고, 야자계, 목탄계, 안트라사이트 순으로 나타났으며, 수온 변화에 따른 chloropicrin, DCAN, TCAN 및 DBAN의 제거 특성은 수온이 $10^{\circ}C$ 이하로 저하될 경우 부착 bacteria의 생체량과 활성도 감소로 제거율이 감소하였다. 안트라사이트를 이용한 생물여과 공정은 수온의 변화에 아주 민감하게 변하는 양상을 나타내었으며, 이는 부착 bacteria에 의한 직접적인 생물분해가 주 제거 메카니즘이기 때문인 것으로 나타났다. Chloropicrin, DCAN, TCAN 및 UBAN과 같은 질소계 염소소독부산물들의 유입농도가 높은 경우 이들의 제거시에는 수온의 영향이 매우 중요하며, 흡착능이 소진된 활성탄이나 흡착능이 없는 여재를 사용한 생물여과 공정에서는 수온이 낮은 동절기에는 이들의 유출 가능성이 있었다.

• 한국기계가공학회지
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• 제21권5호
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• pp.105-109
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• 2022

In the field of medical and marine industries, antibacterial surfaces have been emerged as one of the most important issues. Recently, many researchers have been studying antibacterial surfaces to kill bacteria or prevent the adhesion of bacteria. In their researches, various materials and structures are suggested to inhibit the adhesion of bacteria or kill the attached bacteria. However, chemical materials such as antibiotics or metal could be toxic. Moreover, frequent use of antibiotics causes super bacteria having resistance to antibiotics. In this study, nano-pillar structured surface was fabricated using polyurethane acrylate (PUA) and the mechanically induced antibacterial function was confirmed based on the fabricated nanostructures. Nanostructures can damage the bacterial membrane of Gram-negative bacteria through stretching of bacterial membrane via interaction with the nanostructures and the bacterial membrane. Consequently, the proposed transparent, flexible and nanostructured PUA films can be one of promising candidates for antifouling and antibacterial surfaces which can be applied in various industries.

• 한국광물학회지
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• 제23권4호
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• pp.315-329
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• 2010

자류철석 표면에 부착한 고온성박테리아들과 이차 생성물을 전자현미경분석을 통하여 조사하였다. 일본 산성 온천수에서 채취된 고온성박테리아를 자류철석에 $42^{\circ}C$, $52^{\circ}C$, $62^{\circ}C$에 각각 접종하였다. 반응된 자류철석 표변에는 2차 생성물과 막대 모양의 박테리아들이 각각 부착하여 나타났다. 자류철석 표면에 부착한 박테리아들의 크기는 $0.4{\times}1.5{\mu}m$에서 $0.3{\times}11.9{\mu}m$ 범위였다. 박테리아들은 세포외중합체물질을 생성하는 것으로 관찰되었으며 이들 세포외중합체물질의 기능은 극한 환경으로부터 박테리아 자신을 보호하는 보호막 역할을 하는 것으로 추정되었다. 원소 황, 철수산화물, S와 Fe로 구성된 결정들, 그리고 O, P, Fe 결정들이 2차 생성물로 관찰되었다.

• 한국식품저장유통학회지
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• 제5권4호
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• pp.363-367
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• 1998

본 연구는 김치의 저장방법을 개선하고자 이산화탄소 흡수능력을 가진 수산화칼륨을 가스흡수제로 사용하여 저장중 pH, 산도, 이산화탄소함량 및 젖산균수 그리고 총균수의 변화를 측정하였다. pH는 저장 8일째 수산화칼륨처리 김치에서 4.02로 가식이 가능했지만 무처리 및 수산화칼슘처리 김치에서는 4.0이하로 감소하여 가식이 불가능했다. 산도는 저장 2일째에 수산화칼륨처리 김치가 수산화칼슘 및 무처리 김치에 비해 다소 낮았으며, 이후 모든 김치에서 급격한 증가하였다. 이산화탄소의 발생은 저장중 가스흡수제를 처리한 김치가 처리하지 않은 김치에 비해 감소하는 경향이었다. 총균수는 저장 6일째에 무처리 및 수산화칼슘처리 김치에서 최고치를 나타내었으며, 수산화칼륨처리 김치는 저장 8일째에 최고치를 나타내었다가 이후 감소하였다. 젖산균수의 변화는 모든 김치에서 저장기간이 길어짐에 따라 증가하는 경향을 보였으며, 젖산균수는 저장 10일째에는 가스흡수제를 처리한 김치가 처리하지 않은 김치에 비해 많았다.

• 한국습지학회지
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• 제9권1호
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• pp.115-121
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• 2007

A novel hydrogen fermentation technique by using polyvinyl alcohol (PVA) gel beads as a biomass carrier was investigated. The hydrogen gas was stably produced throughout the experimental period in a continuous reactor. Even though the hydrogen productivity was suddenly decrease by experimental troubles, the bacteria attached to the PVA gel beads played as an inoculum, it was promptly recovered. The hydrogen yield per glucose was not very high ($1.0-1.2mol-H_2/mol-glucose$), thus the optimization of the experimental conditions such as ORP and HRT should be considered to improve the hydrogen productivity. Bacterial community was stable during experimental period after the PVA gel beads applying, which indicated that applying of biomass carrier was specific to keep not only the biomass but also the bacteria commonly. Clostridium species were phylogenetically detected, which suggested that these bacteria contributed to the hydrogen production in the biofilm attached to the PVA gel beads.