• The Journal of Natural Sciences
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• v.11 no.1
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• pp.41-44
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• 1999

For the purpose of improving the UV sterilization for toothbrush, the sterilizing effects by the UV light were studied. When toothbrushes were treated with the UV light for 5, 15, 30, 60 minutes, the sufficient antibacterial effect were shown after 15 minutes with 80% of bactericidal effects. To prevent the brownish stain on the sterilizer which was caused by the long exposure of UV light, no UV treatment for two hours after 15 minutes exposure were scheduled and then 3 minutes re-exposure were performed, which showed 97% of bactericidal effect. Also, the antibacterial effects of the sterilizer showed different results depending on the position of the toothbrush, it was recommended to adjust toothbrush to be exposed by the UV light directly.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.99-105
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• 2012

Purpose: The purpose of this study is to demonstrate inactivation effect of UVA-LED ultraviolet radiation upon Pseudomonas aeruginosa and Staphylococcus aureus which are the major bacteria causing eye diseases. Methods: The small sterilization device was made using UVA-LED of 400 nm. After Pseudomonas aeruginosa was diluted to $10^{-7}$ and Staphylococcus aureus to $10^{-5}$ and diluted solutions were put onto each liquid medium. They were irradiated by 400 nm of UVA for different amount of time; 15 min, 30 min, 60 min, 120 min, 240 min, 360 min and 480 min each. Results: The data from sterilization test was solved to regression line equation and the target log inactivation was obtained. The 3 log inactivation UV irradiation value of Pseudomonas aeruginosa was 54,847 UV dose ($mJ/cm^2$) and irradiation time was 135.42 min while the 3 log inactivation of Staphylococcus aureus was 39,066 UV dose ($mJ/cm^2$) and irradiation time was 98.72 min. Conclusions: The inactivation effect of sterilization method using 400 nm of UVA-LED upon Pseudomonas aeruginosa and Staphylococcus aureus has been verified and it is considered as a useful method in inactivating the contact lenses.

• KSBB Journal
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• v.24 no.3
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• pp.312-320
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• 2009

Stable cell preservation is an essential factor in the regenerative medicine for cell therapies and transplantation of biologic materials. In this study, we studied to provide more stable hypothermic preservation by protection of cell damage during the preservation at $4^{\circ}C$. The result of searching for key components that have excellent efficacy in hypothermic preservation of cells, we have identified the fact that the hypothermic preservation adding protein hydrolysates such as yeast hydrolysate is far superior to others. All protein hydrolysates that are derived from animal, plant and microbe sources have superior efficacy, especially the peptides which have molecular weights under 10 kDa have the best efficacy among the components of protein hydrolysate. The protein hydrolysates prevented the decrease of ATP level in the cells caused by hypothermic environment and they inhibited the generation of ROS. Adding antioxidants and control agents of osmotic pressure were showed to have more superior efficacy in hypothermic preservation. Finally, KUL261 solution (DMEM/F12 1 : 1 medium, yeastolate 1%, $\alpha$-tocopherol $100{\mu}M$, dextran 2.5%), the preservation solution developed in this study, showed the best efficacy in both cell viability and cell growth more than other conventional preservation solutions. In conclusion, the improved hypothermic preservation solution that contains the protein hydrolysates as a key component provide the best preservation efficacy. It provides better efficacy than other preservation solutions and will contribute to both the development of regenerative medicine and global commercialization in this therapeutic field.

• Journal of Korean society of Dental Hygiene
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• v.21 no.5
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• pp.527-533
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• 2021

Objectives: Electrolyzed water has been proven to have antibacterial effects against various microorganisms. However, there are only a few studies about effects of electrolyzed water on oral bacteria. The purpose of this study was to examine the antibacterial effect of electrolyzed water on Streptococcus mutans in vitro. Methods: S. mutans KCOM 1054 was treated with electrolyzed water for 1 or 3 minutes and plated on Mitis Salivarius agar with 15% sucrose and bacitracin. After incubation for 48 hours, colony forming units (CFU) were counted, and dental plaque was quantified by crystal violet staining. Results: The growth of S. mutans was significantly inhibited by electrolyzed water (p<0.001). In addition, the dental plaque formation by S. mutans was decreased in a time-dependent manner by exposure to electrolyzed water (p<0.001). Conclusions: Our results suggest that electrolyzed water can effectively prevent dental caries by inhibiting growth of (and the formation of dental plaque by) S. mutans.

• Korean Journal of Medicinal Crop Science
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• v.9 no.1
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• pp.45-54
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• 2001

The biological activities of ethanol, ethanol: water(1 : 1v/v) and water extracts from Glycyrrhiza uralensis Fisch, glycyrrhizin and enzymatically hydrolyzed glycyrrhizin were compared. About 50% of the growth of MCF7, A549, Hep3B and AGS cells were inhibited in adding 1.0 g/L of the crude extracts, glycyrrhizin and enzymatically hydrolyzed glycyrrhizin. For example, the ethanol extract inhibited 76%, 66% in MCF7 and Hep3B cells by adding 1.0 g/L. For cytotoxicity on human normal liver cell(WRL-68), the crude extracts were scored as above 26%. For the result of antimutagenecity using CHO V79 cell, the crude extracts proved more effective than other samples. The growth of human immune B and T cells were enhanced up to $1.2{\sim}1.3$ times by adding the crude extracts. In inhibitory effect of ${\alpha}-glucosidase$ activity was showed that the ethanol extract, water extract and ethanol: water (1 : 1v/v) extract were appeared 65%, 68%, 62% in adding 1.0 g/L. The higher enhancement of glutathione -S-transferase activity was observed in the ethanol extract as 257% compared to the control in adding 1.0 g/L. From the results, the biological activities of the crude extracts were equivalent or higher than glycyrrhizin and enzymatically hydrolyzed glycyrrhizin.

• Microbiology and Biotechnology Letters
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• v.26 no.5
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• pp.465-469
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• 1998

The quantitative and rapid method for measuring the biodegradation of polymer materials in soil was developed. In this study, cellophane film was used as a model biodegradable polymer and the biodegradation was assayed by measuring the amount of glucose which was produced by a hydrolysis reaction using HCl after collecting the film from soil. Cellophane film was degraded 41.2% in 4 months during winter while it was degraded 76.5% in 2 months during summer. It means that biodegradation in soil is affected by environmental conditions. The biodegradation was also measured in an incubator (30$^{\circ}C$, humidity 50-55%) to exclude the environmental variations. Cellophane film was degraded 94% in that condition in 40 days. The biodegradation showed the first order kinetics and the rate constant was 0.067 (1/day). Acceleration of the biodegradation in soil was also studied. We added cultured soil microorganisms or nutrients such as N, P, and S into the soil. While the addition of microorganisms showed the temporary increase of rate constant, the addition of nutrients not only showed the increase of rate constant from 0.096 (1/day) to 0.21 (1/day) but also maintained the effect continuously.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.265-270
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• 2017

A key virulence factor for urinary tract pathogens is the enzyme urease, which catalyzes the hydrolysis of urea into ammonium ions and carbonic acid. Urease activity plays an important role in the pathogenesis of urinary tract infection. In this study, the inhibitory effect of zerumbone against six urease-producing bacteria (Klebsiella oxytoca, K. pneumoniae, Morganella morganii, Proteus mirabilis, P. vulgaris, and Staphylococcus saprophyticus) and their urease activities were evaluated. The results of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests showed that zerumbone had antibacterial effect against these six urease-producing bacteria. The MIC and MBC of zerumbone ranged from 0.5 to 2 mM and 1 to 4 mM, respectively. In the urease inhibitory assay, zerumbone showed better urease inhibition ($56.28{\pm}2.45-37.83{\pm}3.47%$) than the standard urease inhibitor, acetohydroxamic acid ($40.46{\pm}1.94-22.99{\pm}3.53%$). However, zerumbone did not affect the levels of the urease subunit. These results clearly indicated that zerumbone has antibacterial potential against urease-producing bacteria and possesses excellent bacterial urease inhibition properties.

• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.273-278
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• 2017

In this paper, a post-processing algorithm to suppress reverberation for continuous-wave active sonar system is developed. The developed algorithm is designed for a low-doppler environment where the target echo is not distinguishable from the reverberation. The algorithm is developed based on overlapping nonnegative matrix factorization method. The algorithm analyzes the frequency characteristics of transmitting ping signal, then suppresses the reverberation using time-frequency characteristics of the received signal. Simulations performed in order to evaluate the proposed algorithm, and the results show that the proposed algorithm makes 6 dB signal-to-reverberation ratio enhancement in various reverberation energy conditions.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.613-618
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• 2006

본 논문은 3차원 가상 환경을 탐험하는데 있어서 빠르고 효과적으로 충돌 탐지를 검출하는 방법을 제안하고자 한다. 넓은 가상 공간상에서 개체가 증가하는 것에 비례하여 충돌 탐지의 계산 비용은 기하 급수적으로 증가한다. 이를 효과적으로 처리하기 위하여 BSP-tree 분할 방식과 경계 기둥을 사용한다. BSP-tree 분할 방식은 3차원의 넓은 가상 공간을 여러 하위 공간으로 나누어 충돌 탐지가 이루어지는 공간을 축소한다. 이를 통하여 충돌 탐지 개체의 수가 증가하는 것에 따라 기하 급수적으로 증가하는 경계 기둥의 충돌 탐지 비용을 줄이는 효과를 얻을 수 있다. 경계 기둥은 축소된 하위 공간 상에서 개체간 실제 충돌 탐지가 일어날 가능성 및 충돌 여부를 빠르고 간편하게 판별하도록 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.953-956
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• 2003

천연광물질인 투어멀린은 물분자를 만나면 수소(H$^{+}$)와 수산기(OH$^{-}$)로 분해하여 친수기와 소수기를 구분하여 발생하며, H$^{+}$와 OH$^{-}$는 각각 $H_2O$와 결합하여 활성이 강한 hydronium ion(H$_3$O$^{+}$)과 계면활성 작용이 있는 hydroxyl ion(H$_3$O$_{2-}$ )을 생성한다. 물속에서 불안정한 상태로 존재하는 수산기는 hydroxyl (-)ion을 형성하여 약 알카리성(pH-7.4)을 띄고, 물의 클러스터(cluster)를 세분화하는 수질 개선 기능과 함께 살균, 항균 및 세균번식억제 효과를 갖는다. 그러므로 투어멀린 전기석의 물 분해 효과를 이용하여 이것을 일정 시간 동안 증류수에 침적시킨 뒤, 그 침적수를 대장균이 배양된 액에 드롭시켜 대장균의 변화를 조사하였다. 그 결과, 시간이 경과됨에 따라 대장균 수의 변화가 나타남을 확인하였고, 따라서 투어멀린 침적수의 대장균 증식억제 효과를 확인하였다.