• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.277-281
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• 2004

This study was performed to investigate the antimicrobial effect of the Fraxinus rhynchophylla extracts against food-borne pathogens. First, the Fraxinus rhynchophylla was extracted with methanol at room temperatures, and fractionation of the methanol extracts from Fraxinus rhynchophylla was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol respectively. The antimicrobial activity of the Fraxinus rhynchophylla extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The ethyl acetate extracts of Fraxinus rhynchophylla showed the highest antimicrobial activity against Staphylococcus aureus and Shigella dysenteriae. The synergistic effect has been found in combined extracts of Fraxinus rhynchophylla and Portulaca aleracea as compared to each extracts alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Fraxinus rhynchophylla against Staphylococcus aureus and Shigella dysenteriae. The ethyl acetate extract of Fraxinus rhynchophylla showed strong antimicrobial activity against Staphylococcus aureus at the concentration of 4,000 ppm. The 4,000 ppm of ethyl acetate extract from Fraxinus rhynchophylla retarded the growth of S. aureus more than 24 hours and Shigella dysenteriae up to 36 hours. The ethyl acetate extracts of Fraxinus rhynchophylla has been shown the antimicrobial effect against Staphylococcus aureus and Shigella dysenteriae.

• Environmental and Resource Economics Review
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• v.29 no.1
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• pp.23-45
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• 2020

The rapid economic growth has brought tremendous pressure on the environment and caused severe air pollution in China. This study empirically examines causes of air pollution in China. Panel-corrected standard errors procedure (PCSE) was used to analyze major determinants of increasing or reducing emissions of sulfur dioxide (SO₂) and nitrogen oxides (NO_X) in 30 Chinese provinces. The estimation results show that SO₂ emission is mitigated as per capita regional GDP increases, but the relation between emission of NO_X and per capita regional GDP is found to have an inverse N-shaped curve, which implies that emission of NO_X is ultimately expected to decline with economic growth. As for increasing factors of air pollutants, electricity consumption is a significant common source of SO₂ and NO_X emissions. Moreover, the results show that increment of coal consumption significantly affects emission of SO₂ while increase of natural gas consumption reduce emission of SO₂. On the other side, investment in energy industry, and investment on treatment of waste gases are determinants of mitigating emissions of SO₂, but have no impact on NO_X. Consumption of diesel, truck ratio and number of vehicles increase emission of NO_X. Meanwhile, higher precipitation rate is a common determinant of mitigating emissions of SO₂ and NO_X. Policy implications are suggested in the conclusion.

• Journal of Korea Water Resources Association
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• v.41 no.4
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• pp.405-412
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• 2008

Rainfall quantiles were estimated by applying the FORGEX method. The circle network and two elliptical ones with the ratios of 1 to 1.5 and 1 to 2.0 were used and compared to find appropriate one for rainfall data. Annual maximum data were collected from 376 sites and standardized by the median. The networks were organized from the subject sites and then pooled and netmax data were collected from each network. Then, the growth curves and quantiles were estimated. When the subject site had small differences of quantiles from index flood method and at-site frequency analysis, those of the estimated quantiles from circle and elliptical networks were small. In contrast, the sites where the quantile differences are big have big differences of quantiles from circle and elliptical networks. The estimated quantiles from the elliptical network are more accurate than those from the circle network, because the ellipse network contains more sites in South Korea. Moreover, the ellipse with ratio of 1 to 2.0 shows closer quantiles to those from index flood method than one with ratio of 1 to 1.5. It is, therefore, found that the FORGEX method with 1 to 2.0 ellipse network is appropriate regional frequency analysis in South Korea.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.346-352
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• 2017

In this study, we analyzed environmental factors including annual fruit growth and meteorological conditions in Suwon area from 2000 to 2014 to develop and verify a fruit width prediction model in 'Fuji' apple. The 15-year average of full bloom data was April 28 and that of fruit development period was 181 days. The fruit growth until 36 days after full bloom followed single sigmoid curve. The environmental factors affecting fruit width were BIO2, precipitation in September, the average of daily maximum and minimum temperature in April, minimum temperature in August, and growing degree days (GDD) in April. Among them, the model was constructed by combining BIO2 and precipitation in September, which are not cross-correlated with each other or, with other factors. And then, the final model was selected as 19.33095 + (5.76242 ${\times}$ BIO2) - (0.01891 ${\times}$ September precipitation) + (2.63046 ${\times}$ minimum temperature in April) which was the most suitable model with AICc of 92.61 and the adjusted $R^2$ value of 0.53. The model was compared with the observed values f rom 2000 to 2014. As a result, the mean difference between the measured and predicted values of 'Fuji' apple fruit width was ${\pm}2.9mm$ and the standard deviation was 3.54.

• Fire Science and Engineering
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• v.34 no.1
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• pp.18-25
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• 2020

In this study, the heat release rate of pipe insulation is analyzed by considering the installation status in accordance with the standards ISO 20632 and NFPA 274. The flame retardation rate was evaluated for six types of test samples: polyethylene foam covered with beaten silver (PE(S)), PE foam tapped (PE(N)), elastomeric closed cell thermal insulation (rubber), Japanese PE foam (PE(J)), Japanese polyurethane foam (PU(J)), and Japanese styro form (ST(J)) by EN 13501-1 and fire growth curve. The results show that PU(J), PE(J), and PE(N) were Class E and ultra-fast, NFPA 274 test standards for Class D and Fast, and PE(S) by ISO 20632 were Class C and Slow, and Rubber and ST(J) were Classes and Low. However, the changes in the time-averaged maximum heat release rate for each test standard (ISO 20632 and NFPA 274) to evaluate the flame retardation rate differed among identical materials. This means that the fundamental study is necessary to analyze the more accurate reasons.

• Korean journal of food and cookery science
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• v.21 no.1 s.85
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• pp.40-46
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• 2005

This study was performed to investigate the antimicrobial effects of the Citrus unshiu Markovich extracts against food-borne pathogens. First, the Citrus unshiu Markovich was extracted with methanol at room temperature, and fractionation of the methanol extracts from Citrus unshiu Markovich was carried out by using petroleum ether, chloroform, ethyl acetate, and methanol. The antimicrobial activity of the Citrus unshiu Markovich extracts was determined using the paper disc method against food-borne pathogens and food spoilage bacteria. The ethyl acetate extracts of Citrus unshiu Markovich showed the highest antimicrobial activity against Bacillus cereus and Shigella sonnei. A synergistic effect was found in combined extracts of Citrus unshiu Markovich and Hedyotis diffusa Willd as compared to each extract alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Citrus unshiu Markovich against Bacillus cereus and Shigella sonnei. The ethyl acetate extract of Citrus unshiu Markovich showed strong antimicrobial activity against Bacillus cereus at the concentration of 5,000 ppm. The 5,000 ppm of ethyl acetate extract from Citrus unshiu Markovich retarded the growth of Bacillus cereus more than 24 hours and Shigella sonnei up to 24 hours. The ethyl acetate extracts of Citrus unshiu Markovich have shown an antimicrobial effect against Bacillus cereus and Shigella sonnei.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.67-71
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• 2014

An attempt to grow high quality GaN on silicon substrate using metal organic chemical vapor deposition (MOCVD), herein GaN epitaxial layers were grown on various Si(111) substrates. Thin Platinum layer was deposited on Si(111) substrate using sputtering, followed by thermal annealing to form Pt nano-clusters which act as masking layer during dry-etched with inductively coupled plasma-reactive ion etching to generate nano-patterned Si(111) substrate. In addition, micro-patterned Si(111) substrate with circle shape was also fabricated by using conventional photo-lithography technique. GaN epitaxial layers were subsequently grown on micro-, nano-patterned and conventional Si (111) substrate under identical growth conditions for comparison. The GaN layer grown on nano-patterned Si (111) substrate shows the lowest crack density with mirror-like surface morphology. The FWHM values of XRD rocking curve measured from symmetry (002) and asymmetry (102) planes are 576 arcsec and 828 arcsec, respectively. To corroborate an enhancement of the growth quality, the FWHM value achieved from the photoluminescence spectra also shows the lowest value (46.5 meV) as compare to other grown samples.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.42-46
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• 2017

$SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphorescent phosphors were synthesized by skull melting method. The molar ratio of oxides in the phosphors synthesized by the skull melting technique was $SrCO_3$ : $Al(OH)_3$ : $Eu_2O_3$ : $Dy_2O_3$= 1 : 2 : 0.015 : 0.02. Crystal structure and surface morphology were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Optical properties of the synthesized $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ were measured by photoluminescence (PL) spectrometer for in-depth study on the excitation, emission and afterglow properties. From the PL measurements, it was found that excitation occurred in the wavelength range from 300 to 420 nm with peak position at 360 nm. The emission spectrum showed a broad curve in the wavelength from 450 to 600 nm with peak position at 530 nm. $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphors exhibited afterglow properties with emission that lasted for a long period.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.741-755
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• 1999

As a material of metal-ceramic prosthesis, nickel as a form of Ni-Cr alloy has been used for many dental prostheses in many cases. However, several problems in use of the alloy have been revealed (ex : tissue stimulation, skin allergy, hypersensitivity, cytotoxicity and carcinogenecity). Little is known about nickel with respect to the relationship between Ni-prosthesis and gaining of Ni-resistance in oral microorganisms. The present study was undertaken to check wheather use of Ni-prosthesis leads to occurrence of Ni-resistant microorganisms. So this study may suggest the possible relationships between the oral microorganisms and nickel-resistance in oral environment. Bacteria were isolated from the gingival crevicular fluid on the pateints wearing Ni-Cr prosthesis. The isolated bacteria were tested for their Ni-resistance in nickel containing media at different concentration from 3mM to 110mM. E. coli HB101 was used as control. The Ni-resistant bacteria were isolated and biochemically identified. The Ni-resistant bacteria were tested several bio-chemical, molecular-biological tests. Performed tests were ; measuring the growth curve, antibiotic test, growth ability test in liquid media, isolation of the chromosome and plasmid, digestion of DNA by restriction enzyme, electrophoresis of chromosome and plasmid DNA, identification of Ni-resistant genes by the DNA hybridization. The results were as follows: 1) The bacteria isolated from gingival crevicular fluid on the patients wearing Ni-Cr alloy pros-thesis showed nickel-resistance. 2) The isolated microorganisms grew at nickel containing media of high concentrations (60mM-110mM). 3) Based on the biochemical tests, the isolated microorganisms were identified as Enterococcus faecalis(13 cases), Klebsiella pneumoniae(1 case) and Enterobacter gergeviae(1 case). 4) Enterococcus faecalis expressed not only nickel resistance but also the multi-drug resistance to several antibiotics ; chloramphenicol, kanamicin, streptomycin, lincomycin, clindamycin. However, all strain showed the sensitivity against the tetracycline. 5) DNA hybridization result suggest that there is no homology between the previousely known gene of nickel resistance in Klebsiella pneumoniae and chromosomal DNA of Enterococcus faecalis.

• Development and Reproduction
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• v.20 no.4
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• pp.289-296
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• 2016

This report describes the sex differentiation of the Korean rose bitterling, Rhodeus uyekii, from hatching to 170 days post-hatch (DPH) in relation to total length (TL), body weight (BW), and integral water temperature (IWT). The growth curve of TL from just hatching to 83 DPH was $5.144e^{0.045t}$ ($R^2=0.961$; t, time), and that of BW was $2.398e^{0.086t}$ ($R^2=0.725$). Primordial germ cells (PGCs) were observed at 17 DPH (7.9 mm TL, 3.74 mg BW, $374^{\circ}C$ IWT), and thereafter began to protrude into the peritoneal cavity. At 21 DPH ($9.2{\pm}0.14mm$ TL, $4.8{\pm}0.07mg$ BW, $462^{\circ}C$ IWT), some PGCs contained condensed chromatin and oocyte were observed in meiotic prophase. In contrast to the ovaries, which grew gradually after sexual differentiation, testes began multiplying at 25 DPH (10.1 mm TL, 5.42 mg BW, $550^{\circ}C$ IWT), when testicular differentiation was first identified, and multiplied continuously thereafter. At 33 DPH (11.2 mm TL, 10.5 mg BW, $726^{\circ}C$ IWT), the developing testes contained spermatogonia that exhibited mitotic activity. No spermatocyte or sperm cell was observed until 83 DPH (18.9 TL, 48.2 mg BW, $1,826^{\circ}C$ IWT). At 170 DPH (32.5 mm TL, 270.1 mg BW, $3,740^{\circ}C$ IWT), which was the end point of this study, the mature ovaries showed germinal vesicle breakdown, while the mature testes contained observable spermatocytes and sperm cells. These results allow us to identify the sex differentiation type of the Korean rose bitterling as differentiated gonochoristic.