• The Korean Journal of Applied Statistics
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• v.34 no.3
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• pp.427-438
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• 2021

Two-stage sampling allows us to estimate population characteristics by both unit and cluster level together. Given a complex auxiliary information, integrated calibration weighting would better reflect the level-wise characteristics as well as multivariate characteristics between levels. This paper explored the integrated calibration weighting methods by Estevao and Särndal (2006) and Kim (2019) through a simulation study, where the efficiency of those weighting methods was compared using an artificial population data. Two weighting methods among others are shown efficient: single step calibration at the unit level with stacked individualized auxiliary information and iterative integrated calibration at each level. Under both methods, cluster calibrated weights are defined as the average of the calibrated weights of the unit(s) within cluster. Both were very good in terms of the goodness-of-fit of estimating the population totals of mutual auxiliary information between clusters and units, and showed small relative bias and relative mean square root errors for estimating the population totals of survey variables that are not included in calibration adjustments.

• The Korean Journal of Applied Statistics
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• v.6 no.1
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• pp.125-143
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• 1993

The primary objective of the paper is to review the development of approximations of the null distribution of a scan statistic and to show how these approximations were improved. Let $X_1, \cdots, X_N$ be a sequence of independent uniform random variables on an interval (0, t]. A can statistic is defined to be the maximum number of observations in a subinterval of length t $\leq$ T, when we continuously (or discretely) move the subinterval from 0 to T. A scan statistic is used to test whether certain events occur in a cluster aganist a null hypothesis of the uniformity. It is difficult to calculate the exact null distribution of a scan statistic. Several authors have suggested approximations of the null distribution of a scan statistic since Naus(1966). We conceive that a scan statistic can be used for detecting a "hot region" is defined to be a region at which the frequencies of mutations are relatively high. A "hot region" may be regarded as a generalized version of a hot spot. We leave it for a further study the concrete formulation of deteciton a "hot region" in a mutational spectrum.uot; in a mutational spectrum.

• Journal of Food Hygiene and Safety
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• v.15 no.4
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• pp.297-303
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• 2000

Gamma irradiation at 20 kGy was applied to Kanjang (soy sauce), Doenjang (soybean paste), Kochujang (hot pepper pasts) and Chungkukjang for their possible genotoxicity. The genotoxicity of 20 kGy-irradiated samples was evaluated by Salmonella typhimurium reversion assay. The Salmonella tester strains included TA98, TA100, TA1535 and TA1537 in the absence and presence of an exogenous metabolizing system (59 mix). All samples were negative in the bacterial reversion assay with S. typhimurium TA98, TA100, TA1535 and TA1537. The results indicated that 20 kGy of gamma irradiation on water-soluble fraction of Kanjang, Doenjang, Kochujang and Chungkukjang were not shown mutagenicity.

• Journal of Korean Biological Nursing Science
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• v.16 no.2
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• pp.123-132
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• 2014

Purpose: The purpose of this study was to compare and analyze the effects of gargling using normal saline or essential oil on oral bacterial colonization of the subjects who did transoral endotracheal intubation for general anesthesia. Methods: A repeated measures, non-equivalent control group pretest-posttest design was used in this study. The subjects of the study included 58 people; the gargling group with normal saline (n=19); the gargling group with essential oil (n=20); and the control group (n=19). Data were collected from University hospitals in a Korean province from August 13-31, 2012. The collected data were analyzed with $X^2$-test, t-test, ANOVA and Scheff$\acute{e}$ test using SPSS 19.0. Results: Although statistically significant differences among the three groups did not appear in the change of the aerobic bacterial colony before and after the experiments, the aerobic bacterial colony of the gargling group with normal saline ($71.58{\pm}143.39$) and the group with essential oil ($6.95{\pm}332.07$) have increased less compared to the control group ($145.42{\pm}385.01$). The change of the anaerobic bacterial colony before and after the experiments, the control group was ($167.58{\pm}483.58$) and the gargling group with essential oil was ($169.70{\pm}291.60$) and increased, while the gargling group with normal saline ($-42{\pm}331.09$) reduced, but statistically significant differences have not appeared. Conclusion: These findings indicated that oral gargling with normal saline is effective in reducing anaerobic bacterial colonization.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.95-103
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• 2024

Purpose. With the advancement of digital technology, 3D printing is being utilized in the fabrication of denture base. Nevertheless, increasing microbial adhesion to the surface of denture base has been reported as the disadvantage of 3D-printed denture base. The purpose of this study is to investigate the antifungal properties and flexural strength of 3D-printed denture base resin according to the different contents of titanium dioxide nanoparticles. Materials and methods. Titanium dioxide nanoparticles were mixed with the 3D printing resin at the ratios of 0.5, 1, 1.5, and 2 wt%. Twenty specimens per each group were printed in the form of cylindrical shape (diameter: 20 mm, height: 3 mm) to evaluate antifungal properties. Ten specimens from each group underwent polishing using autogrinder, while the remaining ten specimens did not. Candida albicans in hyphae form was inoculated onto each specimen, optical density and colony-forming unit were analyzed. The surface of the specimen was observed using scanning electron microscopy. To evaluate the flexural strength, twenty specimens per each group were 3D printed in the form of rectangular prism shape (length: 64 mm, height: 10 mm, width: 3 mm) and three-point bending tests were conducted using universal testing machine according to ISO 20795-1. Results. Colony-forming unit of C.albicans and optical density of culture medium showed no difference between non-polished groups, but decreased in the polished groups at concentration of 1, 1.5, 2 wt% titanium dioxide nanoparticles. Flexural strength increased with titanium dioxide nanoparticle at concentration of 0.5, 1, 1.5 wt%, but decreased at 2 wt% compared to 1.5 wt%. Conclusion. When 1.5 wt% of titanium dioxide nanoparticles were added to the 3D-printed denture base resin with polishing, antifungal properties were increased.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.384-386
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• 2014

Pseudomonas aeruginosa is an opportunistic pathogen that inhabits various natural and artificial environments, such as pathogenesis, water, soil and air. They can cause serious problems, such as pathogenic infection. In this study, 220 colonies were isolated from water and soil environment that assumed to be P. aeruginosa using a membrane filter method based on International Organization for Standardization (ISO/NP 16266). Identification of the isolates was determined by physiobiochemical characteristics using newly modified ISO method which includes the resistance to 1,10 phenanthroline test. Only one of 220 presumed P. aeruginosa strains isolated from effluence water using a drain swab was determined as P. aeruginosa-positive by the ISO/NP 16266 method. Subsequently, the resistance to 1,10 phenanthroline test, which was newly proposed by ISO in 2014 and applied in this study, was considered as more precise and improvable method for identification of P. aeruginosa.

• Korean journal of food and cookery science
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• v.17 no.6
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• pp.617-624
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• 2001

Gamma irradiation (1-10 kGy) was applied to chicken for the evaluation of their microbiological safety and possible genotoxicity. In 3 kGy-irradiated sample, the growth of psychrophile was inhibited about 1.5 log cycles and no cells were recovered in total microbial counts. All kinds of contaminated microorganism were sterilized by 7 kGy-irradiation. Also, irradiation followed by freeze-storage at the same time was very effective in inhibiting bacterial growth. The genotoxicity of 10 kGy-irradiated chicken was evaluated by Salmonella Typhimurium reversion assay and in vivo micronucleus assay using mouse bone marrow cells. The results were negative in the bacterial reversion assay with S. Typhimurium TA98, TA100, TA1535, and TA1539. Clastogenic effects were not shown in vivo mouse micronucleus assay at 10 kGy-dose tested.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.339-344
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• 2017

In this study, microorganisms were isolated from nosocomial environment and are identified by biochemical analysis as the part of biochemical and technical convergence. Microorganisms were collected at intense care unit of general hospital located in Pyeongtak (2014.11.28. - 2014. 11. 30). Using a VITEK2 equipment of biochemical approaches, eleven microorganisms e.g., Micrococcus luteus (or M. lylae), Granulicatella adiacens (M. luteus or M. lylae), Staphylococcus caprae, Sphingomonas paucimobilis, Kocuria kristinae, G elegans, Aerococcus viridans (or Staphylococcus arlettae), Methylobacterium spp., Dermacoccus nishinomiyaensis (or Kytococcus sedentarius), Kocuria kristinae (or M. luteus, M. lylae), Pseudomonas oryzihabitans were identified. And then identified bacteria plates were applied with a plastic stick, so called with "FarmeTok (medistick/Puristic) to produce ClO2. ClO2-releasing plastic stick showed the very strong inhibition of bacterial growth with about 99.9%. There were no bacterial colonies on the ClO2-incubated plate. Taken together, it is suggested that chlorine dioxide should be very strong inhibitor to microorganisms of nosocomial infections.

• Tuberculosis and Respiratory Diseases
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• v.64 no.4
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• pp.293-297
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• 2008

Mycobacterium fortuitum usually causes colonization or transient infection in patients with underlying lung disease, such as prior tuberculosis or bronchiectasis. The majority of these patients may not need to receive antibiotic therapy for M. fortuitum isolates. We report here on a patient with M. fortuitum lung disease and who was successfully treated with combination oral antibiotic therapy. A 53-year-old woman was referred to our institution because of purulent sputum and dyspnea. A chest radiograph and computed tomography scan revealed cavitary consolidation in the left upper lobe and multiple small cavities in the left lower lobe. Numerous acid-fast bacilli (AFB) were seen in multiple sputum specimens and M. fortuitum was identified by culture from the sputum specimens. The patient received antibiotic treatment including clarithromycin, ciprofloxacin and sulfamethoxazole, because her symptoms were worsening despite conservative treatment. Sputum conversion was achieved after one month of antibiotic therapy. Both the patient's symptoms and radiographic findings improved after 10 months of antibiotic therapy.

• Food Science and Preservation
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• v.8 no.1
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• pp.54-59
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• 2001

The three medicinal herbs, Astragali Radix, Glycyrrhizae Radix and Aurantii nobilis Pericarpium, irradiated with γ-rays have been tested for their possible genotoxicity. The hot water extracts of the 10 kGy γ-ray irradiated herbs were examined in the Salmonella mutagenicity test(histidine reversion assay; Ames test) using Salmonella. typhimurium TA98 and TA100 as tester strains. No mutagenicity was detected in this assay both with and without metabolic activation. The safety of the herbs irradiated with γ-rays at tactical doses needs to be evaluated in further tests of genotoxicity in vivo and chronic and reproductive toxicity.