• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.225-234
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• 2008

Recently interesting in development of antimicrobial agent from natural origin has been increased in these days. Many studies have been reported antimicrobial effect of Horseradish(Armoracia rusticana) root extracts against various microorganisms such as Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Vibrio parahaemolyticu, Staphylococcus aureus, Bacillus subtilis, Aspergillus parasiticus, Helicobacter pylori. The main component related to antimicrobial activity in horseradish is well known as allyl isothiocyanate(AIT). In this study, we investigated the antimicrobial effects of Horseradish(Armoracia rusticana) root extracts against Streptococcus mutans isolated from human dental plaque, Streptococcus mutans reference strain and compared with that of chlorhexidine. Horseradish root extracts and chlorhexidine were tested to determine their minimum inhibitory concentration( MIC) and minimum bactericidal concentration(MBC). The result of this study can be summerized as follows; 1. Horseradish root extracts showed antimicrobial effect against both S. mutans isolated strain and reference strain, their MIC were respectively $0.083{\sim}0.25%$ ($833.33{\sim}2500 ppm$), 0.25% (2500 ppm). Horseradish root extracts showed antimicrobial effect against S. mutans isolated strain at same or slightly lower concentration compared with MIC of reference strain. 2. $0.083{\sim}0.25%$ horseradish root extracts showed similar antimicrobial effect with chlorhexidine ($0.0021{\sim}0.0041%$).

• Journal of Life Science
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• v.16 no.4
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• pp.664-671
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• 2006

We obtained 424 Salmonella enterica serovar Typhi isolates from sporadic cases of infection in Busan during 1996 to 2005. We investigated the trend of antimicrobial resistance and molecular typing by pulsed-field gel electrophoresis (PFGE). Of the total 424 isolates, 6 strains (1.4%) were multidrug-resistant (MDR) S. enterica serovar Typhi isolates, 2 strains (0.5%) were resistant to only nalidixic acid, and the remaining 416 strains (98.1%) were fully susceptible to the 18 antimicrobial agent. PFGE of XbaI-digested chromosomal DNA was performed on 50 sporadic S. enterica serovar Typhi isolates with the objective of investigating the extent of genetic diversity of these isolates in our region. We could find that these isolates were much more heterogeneous and at least 32 different PFGE patterns were generated according by dice coefficient, between 0.69 and 1.0. Restriction fragment patterns consisted of 13 to 18 fragments ranged in size from 20 to 630 kb. The results confirmed that PFGE would be an useful tool for investigating surveillance of sporadic or outbreak case and assessing clonality for S. enterica serovar Typhi in Busan area. Our finding will be valuable in developing rational strategies to control this pathogen and setting the basis of an effective PulseNet system in Korea.

• Resources Recycling
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• v.27 no.4
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• pp.50-56
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• 2018

For the purpose of optimizing the counter current extraction process for separation of [Pr, Nd, Sm] group and [La] in mixed solution using Cyanex 572 as an extractant, the theory of Xu Guangxian was derived for calculating the optimized extraction factors. From the basic batch test result, the separation factor was 16.80 at extraction process and 21.48 at scrubbing process, and the loading capacity of 1.0 M Cyanex 572 was 0.12 M of rare earth element. The process parameters such as the stage number at extraction and scrubbing process, the flow rate ratio of feed and solvent solution can be calculated using an equation of optimum extraction ratio proposed by Xu Guangxian. From the result of calculation, 7 extraction stages and 4 scrubbing stages were required for rare earth separation, and the flow rate ratio of feed solution, solvent solution, scrubbing solution was 25 : 5.67 : 12.27.

• Journal of the Korean association of regional geographers
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• v.13 no.5
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• pp.477-494
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• 2007

This paper offers a brief overview of the historical implications of residential segregation in Busan, Korea. It first reviews the history of residence from the early 1900s to the present and the transition of residential boundary of the City of Busan. It then considers the characteristics of residential segregation and the important factors in it. The social class of pre-industrial society led the inequality of residential areas around the Eubchee. The existed Korean residential areas were separated by newly built-up residential areas in the Japanese colonial era. After the liberation from Japanese Rule and Korean War, rapid population growth made considerable slums across the City of Busan. These slums were an important factor to segregate residential areas from prosperous areas ever afterward. The socio-economic status has related to residential segregation through the formation of differential housing classes since 1990s. The historial analysis of these periods will offer an insight into how the dominant factors lead residential segregation in a specific period by promoting a more socio-economically integrated society.

• The Korean Journal of Applied Statistics
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• v.33 no.3
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• pp.347-355
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• 2020

An Isolation-with-Migration (IM) model is used to estimate extant population sizes, the splitting time of populations split away from their common ancestral populations, and migration rates between the extant populations. An evolutionary model such as IM models is estimated by analyzing DNA sequences sampled from the extant populations in the model. When a true model includes an unsampled 'ghost' population without data, the unsampled population is often ignored from the evolutionary model to infer. In this paper, we conduct a simulation study to investigate the effect of an unsampled population on the estimation of the size of the sampled population. When there exists an unsampled population that shares migrations with the sampled population, the size estimation of the sampled population was biased. However, the size estimation was improved if an evolutionary model, including the unsampled population, was estimated.

• Korea journal of population studies
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• v.35 no.2
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• pp.185-208
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• 2012

This study examines how married immigrant women's social networks affect their life satisfaction in Korea. A multiple-regression analysis is conducted using data from Nationwide Multicultural Family Survey in 2009. The major findings are as follows. First, the frequency of keeping in touch with their family in the mother country significantly affects the level of satisfaction, while the family size in Korea is not making a significant difference. Second, the strength of "Korean Network" - strong bridging network - is highlighted. Third, family gathering variables affect the level of satisfaction. An interesting point is found from the nationality segmentation. The case of women from Japan, with the longest duration in Korea, shows that both of the family and the non-family gathering variables significantly affect the life satisfaction. It is interpreted that family network dominates in the earlier stage of marriage, but the other social networks also play the role as the duration extends.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.3
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• pp.233-241
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• 2012

Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizer by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. The aim of this study was to evaluate the effect of PDT on Streptococcus mutans in planktonic conditions, previously treated with different photosensitive concentrations of erythrosine, using halogen and LED curing unit as a light source. And we compared the effects of PDT on six strains of S. mutans isolated from oral cavity and reference strain. As a result, S. mutans was susceptible to the combination of hand held photopolymerizer (HHP) and erythrosine. The higher concentration of erythrosine in the presence of light irradiation induced greater effects in reduction of viability of S. mutans. Isolated S. mutans showed a significant reduction in bacterial counts of the groups submitted to PDT compared to the control groups. And they appeared to be similar or slightly lower antimicrobial effect compared with reference strain. However, the difference was not significant (p < 0.05). In conclusion, PDT using erythrosine as a photosensitizing agent and HHP as a light source could be an efficient option for diseases caused by S. mutans.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.648-654
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• 2011

Staphylococcus aureus, a major human pathogen, produces a wide array of toxins, which causes various types of disease symptoms. Prevalence of S. aureus in various foods collected during 2006-2008 in Korea was investigated. S. aureus was isolated from 275 of 5,186 (5.3%) food samples collected from hyper-markets in Korea. Seasonal temperature affected the prevalence of S. aureus in various foods with high isolation rate during the summer. Most of the enterotoxigenic strains produced enterotoxin A only or enterotoxin A in combination with another toxin. A total of 54.5% of the tested strains contained either one or more enterotoxin genes and 3.6% possessed a tst gene. This study offers basic information for securing the stability of food during storage and circulation, and provides an epidemiological tool to study the cause, origin and temporal spread of S. aureus food poisoning.

• Applied Microscopy
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• v.33 no.4
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• pp.261-266
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• 2003

The growth patterns of primary culture of bovine brain microvessel endothelial cells (BBMECs) were studied using electron microscopy when grown on $3.0{\mu}m$ and $0.4{\mu}m$ pore Transwell. The capillary fragments and isolated endothelial cells grew on collagen coated culture plate and Transwell membrane. The BBMECs grew only on the upper surface of membrane of $0.4{\mu}m$. But BBMECs on $3.0{\mu}m$ pore membrane migrated through the pore and grew on the opposite side of the membrane. In summary, BBMECs isolated by enzyme digestion could migrate through $3.0{\mu}m$ pore membrane but not through $0.4{\mu}m$ pore membrane. So $0.4{\mu}m$ pore membrane instead of $3{\mu}m$ pore membrane should be used for drug transport experiment or transendothelial electrical resistance measurement.

• Journal of Life Science
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• v.15 no.2 s.69
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• pp.161-168
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• 2005

In this study, we did the molecular typing of 39 environmental Legionella pneumophila serogroup 1 isolates collected from 2001-2003 in Busan using the pulsed-filed gel electrophoresis (PFGE). PFGE of SfiI fragments were divided into 10 pulsotypes $(A\~J)$, corresponding to $<65\%$ similarity and a subtype within each pulsotype was characterized by $>84\%$ similarity. The major cluster was pulsotype E $(46.2\%)$, which included 18 isolates and was divided into 4 subtypes $(E1\~E4)$. PFGE of NotI fragments were divided into 8 pulsotypes $(a\~h)$, corresponding to $<60\%$ similarity and a subtype within each pulsotype was characterized by $100\%$ similarity. The major cluster was pulsotype f $(38.5\%)$, which included 15 isolates. The ATCC type strain L. pneumophila serogroup 1 was identified as a different molecular pulsotype compare to the Busan isolates. It is possible that L. pneumophila serogroup 1 isolated in Busan with specific DNA pattern is comparable with those isolation in other cities in Korea.