• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.15 no.3
• /
• pp.140-147
• /
• 2010

We investigated the effects of water temperature, salinity and irradiance on the growth of the harmful algae Chattonella ovata isolated from South Sea, Korea. C. ovata grew under all combinations of water temperatures and salinity, except for all the salinity conditions at the water temperature of $10^{\circ}C$, with the salinity of 7.5 psu and 10 psu at $15^{\circ}C$, and 7.5 psu at $20^{\circ}C$ and $30^{\circ}C$. The maximum specific growth rate was $0.62\;day^{-1}$ at the combination of $30^{\circ}C$ and 30 psu. The results of two-way ANOVA indicated that growth rate depended greatly on the water temperatures while not being affected by interactions with the salinity. This indicates that C. ovata is a stenothermal and euryhaline organism, preferring high water temperatures. C. ovata did not grow at irradiance ${\leq}30\;{\mu}mol$ photons $m^{-2}s^{-1}$. Photoinhibition did not occur at $800\;{\mu}mol$ photons $m^{-2}s^{-1}$, which was the maximum irradiance used in this study. The irradiance-growth curve was described as $\mu$ = 0.74(I-16.0)/(I+43.9) at $30^{\circ}C$ and 30 psu. The half-saturation light intensity ($K_s$) was $75.9\;{\mu}mol$ photons $m^{-2}s^{-1}$ and compensation photon flux density ($I_c$) was $16.0\;{\mu}mol$ photons $m^{-2}s^{-1}$, especially this value was comparatively lower than those of Skeletonema costatum and other flagellates previously reported. Therefore, our results indicate that C. ovata has advantageous physiological characteristics for interspecific competition at the embayment and coastal areas of Korea in summer.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.32 no.E
• /
• pp.1-19
• /
• 1990

Abstract Over the last several decades, crop production in the United States increased largely due to the extensive use of animal waste and fertilizers as plant nutrient supplements, and pesticides for crops pests and weed control. Without the application of animal waste best management, the use of animal waste can result in nonpoint source pollution from agricultural land area. In order to increase nutrient levels and decrease contamination from agricultural lands, nonpoint source pollution is responsible for water quality degradation. Nonpoint source pollutants such as animal waste, ferilizers, and pesticides are transported primarily through runoff from agricultural areas. Nutrients, primarily nitrogen and phosphorus, can be a major water quality problem because they cause eutrophic algae growth. In 1985, it was presented that Watershed/Water Quality Monitoring for Evaluation BMP Effectiveness was implemented for Nomini Creek Watershed, located in Westmoreland County, Virginia. The watershed is predominantly agricultural and has an aerial extent of 1505 ha of land, with 43% under cropland, 54% under woodland, and 3% as homestead and roads. Rainfall data was collected at the watershed from raingages located at sites PNI through PN 7. Streams at stations QN I and QN2 were being measured with V-notch weirs. Water levels at the stream was measured using an FW-l Belfort (Friez FWl). The water quality monitoring system was designed to provide comprehensive assessment of the quality of storm runoff and baseflow as influenced by changes in landuse, agronomic, and cultural practices ill the watershed. As this study was concerned with the Nomini Creek Watershed, the separation of storm runoff and baseflow measured at QNI and QN2 was given by the master depletion curve method, and the loadings of baseflow and storm runoff for TN (Total Nitrogen) and TP (Total Phosphorus) were analyzed from 1987 through 1989. The results were studied for the best management practices to reduce contamination and loss of nutrients, (e.g., total nitrogen and total phosphorus) by nonpoint source pollution from agricultural lands.

• Journal of Digital Convergence
• /
• v.16 no.4
• /
• pp.49-54
• /
• 2018

Russia has access to unique port locations and routes, one of them is North Sea route, which have been a major debate topic for last several decades. In order to handle any shipments along the route, an adequate and capable port system must be present. This study aims to identify development and competition patterns from 2007 to 2016 of Russian ports in the Arctic basin, concentration trends in particular. The objectives achieved through utilizing the Herfindahl-Hirschman Index (HHI), concentration ratio (CR), the Gini coefficient and Lorenz curve, and shift-share analysis. Results demonstrate concentration trend, positive overall growth and lack of real competition. Originality of this study lies in the fact that certain analysis had not been done in previous studies, but importance of it may be found in several papers. Findings of this paper may assist policy-makers, port authorities and other researchers in understanding and further study on the region.

• Korean Journal of Microbiology
• /
• v.53 no.3
• /
• pp.193-199
• /
• 2017

This study was aimed to evaluate the antimicrobial activity of Penicillium purpurogenum ED76 on several clinically important microorganisms. The endophytic fungus P. purpurogenum ED76 was previously isolated from Swietenia macrophylla leaf. The antimicrobial efficacy of P. purpurogenum ED76 dichloromethane extract was determined via disc diffusion and broth microdilution assay. A kill curve study was conducted and the morphology of extract treated bacterial cells were viewed under scanning electron microscope. The dichloromethane extract showed significant inhibitory activity on 4 test bacteria and 2 test yeasts. The minimal inhibitory concentration of the extract ranged from 125 to $1,000{\mu}g/ml$, which indicates the different susceptibility levels of the test microorganisms to the fungal extract. The kill curve study has revealed a concentration-dependent inhibition for all test microorganisms. With the increase of the extract concentration, the microbial growth was significantly reduced. The scanning electron micrograph of dichloromethane extract-treated Staphylococcus aureus cells showed the total damage of the cells. The cell wall invagination of the bacterial cells also indicates the loss of cellular materials and metabolic activity. The gas chromatography mass spectrometry analysis of the extract also showed that the major compound was stigmasterol, which constitutes 45.30% of the total area. The dichloromethane extract of P. purpurogenum ED76 exhibited significant inhibitory activity on several clinically important bacteria and yeasts. The study proposed a possible mode of action that the extract cause significant damage to the morphology of S. aureus cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04b
• /
• pp.56-59
• /
• 2004

The stochiometric composition of $AgGaS_2$ polycrystal source materials for the $AgGaS_2/GaAs$ epilayer was prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns it was found that the polycrystal $AgGaS_2$ has tetragonal structure of which lattice constant $a_0$ and $c_0$ were 5.756 ${\AA}$ and 10.305 ${\AA}$, respectively. $AgGaS_2/GaAs$ epilayer was deposited on throughly etched GaAs (100) substrate from mixed crystal $AgGaS_2$ by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $590^{\circ}C$ and $440^{\circ}C$ respectively. The crystallinity of the grown $AgGaS_2/GaAs$ epilayer was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for $AgGaS_2/GaAs$ epilayer at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by ${\alpha}=8.695{\times}10^{-4}eV/K$, and $\beta$=332 K. From the photocurrent spectra by illumination of polarized light of the $AgGaS_2/GaAs$ epilayer, we have found that crystal field splitting $\Delta$ Cr was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pairs are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.281-287
• /
• 2002

The stochiometric composition of AgGaS$_2$ polycrystal source materials for the AgGaS$_2$/GaAs epilayer was prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns it was found that the polycrystal AgGaS$_2$ has tetragonal structure of which lattice constant a$\sub$0/ and c$\sub$0/ were 5.756 ${\AA}$ and 10.305 ${\AA}$, respectively. AgGaS$_2$/GaAs epilayer was deposited on throughly etched GaAs(100) substrate from mixed crystal AgGaS$_2$ by the Hot Wall Epitaxy (100) system. The source and substrate temperature were 590$^{\circ}C$ and 440$^{\circ}C$ respectively. The crystallinity of the grown AgGaS$_2$/GaAs epilayer was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for AgGaS$_2$/GaAs epilayer at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by ${\alpha}$ : 8.695${\times}$10$\^$-4/ eV/K, and ${\beta}$ = 332 K. From the photocurrent spectra by illumination of polarized light of the AgGaS$_2$/GaAs epilayer, we have found that crystal field splitting ΔCr was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pain are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.2
• /
• pp.93-101
• /
• 2007

In order for bioremediate the benthic layer in polluted inner Bay, the effects of irradiance and wave-length irradiated from light emission diode (LED) on the growth of benthic diatom Nitzschia sp. (Hakozaki Bay strain of Japan) were investigated. The Nitzschia sp. was cultured under blue LED (450 nm), yellow LED (590 nm), red LED (650 nm) and fluorescent lamp (mixed wavelengths). At $25^{\circ}C$ and 30 psu, the growth of Nitzschia sp. showed its peak at $20\;{\mu}mol\;m^{-2}\;s^{-1}$ (blue LED) and $40\;{\mu}mol\;m^{-2}\;s^{-1}$ (fluorescent lamp), and was inhibited at the irradiance higher than that irradiance. Nitzschia sp. in yellow LED and red LED is fitted by a rectangular hyperbolic curve because no photoinhibition was observed under maximum irradiance used in this study. The irradiance-growth curves were described as ${\mu}=-0.46{\exp}(1-I/6.32)+0.46-0.00043I,\;(r^2=0.98)$ under blue LED, ${\mu}=0.42(I+7.87)/(I+58.9),\;(r^2=0.99)$ under yellow LED, ${\mu}=0.39(I+3.39)/(I+21.6),\;(r^2=0.94)$ under red LED, ${\mu}=-0.38{\exp}(1-I/7.23)+0.38-0.00016I,\;(r^2=0.96)$ under fluorescent lamp. Maximum specific growth rate of blue LED, yellow LED, red LED and fluorescent lamp was $0.44\;day^{-1},\;0.42\;day^{-1},\;0.39\;day^{-1}$ and $0.37\;day^{-1}$, respectively. The absorption coefficient ($a_{ph}$) of Nitzschia sp. was similar under all the wavelengths (400 nm-700 nm), although maximum $a_{ph}$ was $0.0224\;m^2\;mg\;chi.\;{\alpha}^{-1}$ in 472 nm and $0.0179\;m^2\;mg\;chi.\;{\alpha}^{-1}$) in 663 nm. The results may indicate the possibility of environmental improvement around the benthic layer in polluted coastal area because microphytobenthos growth is stimulated by means of irradiated blue LED at the benthic boundary layer during both autumn and winter, and yellow LED, which might have been suppressed growth of harmful algae, at the layer during both spring and summer.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.23 no.2
• /
• pp.20-37
• /
• 2010

Purpose: The objective of this study was to observe the antibacterial effects of Sasangjasaebang (SSJSB) aqueous extracts, traditionally used for treating various gynecological diseases including vaginitis in Korea and their individual components - Cnidi Fructus(CF), Zanthoxyli Fructus(ZF) and Alumen(AL) against Gardnerella vaginalis ATCC14018, and combination effects of SSJSB extracts and Metronidazole were also monitored in this study. Methods: Antibacterial activities against Gardnerella vaginalis ATCC14018 of SSJSB (CF : ZF : AL = 10 : 3 : 3) aqueous extracts and their individual components were detected using standard agar microdilution methods. In addition, the effects on the bacterial growth curve were also monitored at MIC and $MIC{\times}2$ levels. The combination effects of SSJSB aqueous extracts and Metronidazole were observed by Checkboard Microtiter Assay and effects on bacterial growth curve treated with SSJSB aqueous extracts MIC + Metronidazole MIC, 1/2MIC and 1/4MIC, respectively. In the present study, Gardnerella vaginalis ATCC14018 were incubated under $37^{\circ}C$, 10% CO2 and bacterial growth curves were calculated at 24, 48, 72, 96 and 120 hrs after incubations. Results: MIC of CF aqueous extracts, ZF aqueous extracts, AL powders and SSJSB aqueous extracts against Gardnerella vaginalis ATCC14018 were detected as $27.5\;{\pm}\;13.693$(12.5~50), $6.875\;{\pm}\;3.423$(3.125~12.5), $4.375\;{\pm}\;1.713$(3.125~6.25) and $2.188\;{\pm}\;0.856(1.563{\sim}3.125)mg/m{\ell}$, respectively. MIC of Metronidazole was detected as $7.6\;{\pm}\;5.367(2{\sim}16){\mu}g/m{\ell}$ at same conditions. In addition, Metronidazole, CF aqueous extracts, ZF aqueous extracts, AL powders, and SSJSB aqueous extracts showed marked dosage-dependent inhibition of bacterial growth, and more dramatical inhibitions were detected in Metronidazole 1/2 MIC + SSJSB aqueous extracts MIC treatment as compared with each of single Metronidazole MIC and SSJSB aqueous extracts MIC treatments, respectively. Especially, quite similar inhibitory effects on bacterial growth were detected in Metronidazole 1/4 MIC + SSJSB aqueous extracts MIC treatment as compared with single Metronidazole MIC treatment in the present study. FIC index were detected as $0.475\;{\pm}\;0.137$(0.375~0.625) at Checkboard Microtiter Assay. Conclusion: The results obtained in this study suggest that CF aqueous extracts, ZF aqueous extracts, AL powders, and SSJSB aqueous extracts showed antibacterial effects against Gardnerella vaginalis ATCC14018, and they also showed dosage-dependent inhibitory effects on the bacterial growth. More potent antibacterial effects were detected in SSJSB aqueous extract as compared with individual components, respectively. In addition, combination treatment of SSJSB aqueous extract and Metronidazole showed more potent inhibitory effects on the growth of Gardnerella vaginalis with FIC index $0.475\;{\pm}\;0.137$(0.375~0.625). According to these results, the combination of SSJSB aqueous extract and Metronidazole is synergistic, and it is expected that effective dosages of Metronidazole could be reduced to 1/4 levels in combination with SSJSB extracts. And it might be needed to make further studies to seek the herbs which have antibacterial effects on the Gardnerella vaginalis ATCC14018.

• Journal of Nutrition and Health
• /
• v.38 no.2
• /
• pp.112-116
• /
• 2005

This study was performed to investigate the antimicrobial effect of the Agrimonia pilosa Ledeb. extracts against food-borne pathogens. First, the Agrimonia pilosa Ledeb. was extracted with methanol at room temperatures, and fractionation of the methanol extracts from Agrimonia pilosa Ledeb. was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol respectively. The antimicrobial activity of the Agrimonia pilosa Ledeb. extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The petroleum ether extracts of Agrimonia pilosa Ledeb. showed the highest antimicrobial activity against Pseudomonas aeruginosa. The synergistic effect has been found in combined extracts of Agrimonia pilosa Ledeb. and Perillae folium as compared to each extracts alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Agrimonia pilosa Ledeb. against Bacillus Cereus and Salmonella Enteritidis. The petroleum ether extract of Agrimonia pilosa Ledeb. showed strong antimicrobial activity against Bacillus Cereus at the concentration of 4,000 ppm. The 4,000 ppm of petroleum ether extract from Agrimonia pilosa Ledeb. retarded the growth of Bacillus Cereus more than 24 hours and Salmonella Enteritidis up to 36 hours. The petroleum ether extracts of Agrimonia pilosa Ledeb. has been shown the antimicrobial effect against Bacillus Cereus and Salmonella Enteritidis. (Korean J Nutrition 38(2): 112～116, 2005)

• Microbiology and Biotechnology Letters
• /
• v.33 no.1
• /
• pp.35-40
• /
• 2005

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