To investigate the perceptions and attitudes of dental hygienists toward radiation safety management in Korea. A total of 800 dental hygienists were randomly selected for an anonymous survey, and 203 of them participated. The questionnaire items included the following: sex, career period, type of installed radiographic equipment, recognition of the diagnostic reference level (DRL), participation in radiation safety education, and attitudes toward radiation protection for both patients and dental hygienists. The participants were divided into two groups according to their years of experience (< 10 years versus ≥ 10 years). The difference between the groups was investigated according to frequency distribution. Fisher’s exact test or Pearson’s chi-square (χ2) test was used as appropriate. A regression analysis was performed to investigate the impact of wearing a thyroid collar for personnel protection during patient radiation exposure. The types of installed radiographic equipment included panoramic radiography (96.1%), cephalometric radiography (76.9%), intraoral radiography (72.9%), and cone-beam computed tomography (69.5%). Significant differences were observed in the learning pathway for the DRL (Fisher’s exact test, p < 0.05), satisfaction with radiation safety education (Pearson’s χ2 test = 5.3975, Pr = 0.02), and use of personnel radiation monitoring systems (Pearson’s χ2 test = 18.1233, Pr = 0.000) between the groups. Significant differences were also observed in personnel protection using a thyroid collar and patient protection during panoramic radiography (odds ratio = 14.2). Dental hygienists with more than 10 years of experience were more satisfied with radiation safety education and more interested in radiation monitoring. Considering career experience, customized, continuous, and effective radiation safety management education should be provided.

An antimicrobial substance-producing microorganism was isolated from soil samples. Based of the taxonomic characteristics of its morphological, cultural, physiological properties and 16s rRNA sequence alignment, this microorganism was identified as Pseudomonas aeruginosa, and we named Pseudomonas aeruginosa EL-KM. The optimal culture condition for production of antimicrobial substance was 1% mannitol, 0.4% yeast extract, 0.5% Nacl, 0.2% K₂SO₄, 100μM MgSO₄.7H2O, 10μM CaCl2.$2H_2O$, 1μM $FeSO_4$.7H2O, 1μM MnSO4.$4-5H_2O$, initial pH 7 and 200 rpm at 30℃. The purification of the antimicrbial substance was performed by silica gel column chromatographys, and fraction with TLC $R_f$ 0.77 value represented good antimicrobial activity. The crude antimicrbial substance was stable within a pH range of 3-10 and temperature range of 4°C-121°C autoclaving. This crude antibacterial substance acted as bacteriolytic agent against Vibrio cholerae non-Ol ATCC 25872, and also exhibited excellent properties, when the substance was demonstrated against many other gram-positive, gram-negative bacteria, yeast and fungi.