• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.413-433
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• 1994

Jinhae Bay once was a productive area of fisheries. It is, however, now notorious for its red tides; and oxygen deficient water-masses extensively develop at present in summer. Therefore the shellfish production of the bay has been decreasing and mass mortality often occurs. Under these circumstances, the three-dimensional numerical hydrodynamic and the material cycle models, which were developed by the Institute for Resources and Environment of Japan, were applied to analyze the processes affecting the oxygen depletion and also to evaluate the environment capacity for the reception of pollutant loads without dissolved oxygen depletion. In field surveys, oxygen deficient water-masses were formed with concentrations of below 2.0mg/l at the bottom layer in Masan Bay and the western part of Jinhae Bay during the summer. Current directions, computed by the $M_2$ constituent, were mainly toward the western part of Jinhae Bay during flood flows and in opposite directions during ebb flows. Tidal currents velocities during the ebb tide were stronger than that of the flood tide. The comparision between the simulated and observed tidal ellipses showed fairly good agreement. The residual currents, which were obtained by averaging the simulated tidal currents over 1 tidal cycle, showed the presence of counterclockwise eddies in the central part of Jinhae Bay. Density driven currents were generated southward at surface and northward at the bottom in Masan Bay and Jindong Bay, where the fresh water of rivers entered. The material cycle model was calibrated with the data surveyed in the field of the study area from June to July, 1992. The calibrated results are in fairly good agreement with measured values within relative error of $28\%$. The simulated dissolved oxygen distributions of bottom layer were relatively high with the concentration of $6.0{\sim}8.0mg/l$ at the boundaries, but an oxygen deficient water-masses were formed within the concentration of 2.0mg/l at the inner part of Masan Bay and the western part of Jinhae Bay. The results of sensitivity analyses showed that sediment oxygen demand(SOD) was one of the most important influence on the formation of oxygen depletion. Therefore, to control the oxygen deficient water-masses and to conserve the coastal environment, it is an effective method to reduce the SOD by improving the polluted sediment. As the results of simulations, in Masan Bay, oxygen deficient water-masses recovered to 5.0mg/l when the $50\%$ reduction in input COD loads from Masan basin and $70\%$ reduction in SOD was conducted. In the western part of Jinhae Bay, oxygen deficient water-masses recovered to 5.0mg/l when the $95\%$ reduction in SOD and $90\%$ reduction in culturing ground fecal loads was conducted.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.344-357
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• 2020

Strain improvement and bioprocess development were undertaken to enhance hyaluronic acid(HA) production by Streptococcus zooepidemicus cells. Using a high-yielding mutant strain, statistical medium optimization was carried out in shake flask cultures, resulting in 52% increase in HA production (5.38 g/l) at the optimal medium composition relative to the parallel control cultures. For sufficient supply of dissolved oxygen (DO), which turned out to be crucial for enhanced production of HA, agitation system and speed were intensively investigated in 5 L bioreactor cultures. Increase in oxygen mass transfer coefficient (k_La) through increment of agitation speed (rpm) and 35% expansion of diameter of the newly-designed impellers showed significantly positive effects on HA production. By installing an expanded Rushton-turbine impeller for efficient break-down of sparged air, and an extended marine impeller above the Rushton-turbine impeller for efficient mixing of the air-born viscous fermentation broth, maximum amount of HA (9.79 g/l) was obtained at 450 rpm, 1.8 times higher level than that of the corresponding flask culture. Subsequently, the possibility of bioprocess scale-up to a 50 L bioreactor was investigated. Despite almost identical maximum HA production (9.11 vs 9.25 g/l), the average HA volumetric productivity (r_p) of the 50 L culture turned out only 74% compared to the corresponding 5 L culture during the exponential phase, possibly caused by shear damages imposed on the producing cells at the high stirring in the 50 L culture. The scale-up process could be successfully achieved if a scale-up criterion of constant oxygen mass transfer coefficient (k_La) is applied to the 50 L pilot-scale bioreactor system.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.265-271
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• 1994

This study was conducted to determine the herbicidal activity, persistance, downward movement and effect on bentgrass of 7 dinitroaniline herbicides such as benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl) benzenamine], beslogine [N,N-dibutyl-2,6-dinitro-4-trifluoromethylaniline], prodiamine [2,4-dinitro-$N^3$,$N^3$-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine], pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl) benzenamine], ethalfluralin [N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine], and oryzalin [4-(diprop-ylamino)-3,5-dinitrobenzene-sulfonamide) together with bensulide [O,O-bis(1-methylethyl) S-[2-[(phenyl-sulfonyl) amino]ethyl]phosphorodithioate] and siduron [N-(2-methylcyclohexyl)-N'-phenylurea) as the control. In addition, distribution of pendimethalin and benefin into bentgrass was also determined. Prodiamine, benefin, and pendimethalin at the 1/16 dose of the recommended rate showed very high herbicidal activity($LD_{90}$) on Digitaria sanguinalis, but ethalfluralin and bensulide showed $LD_{90}$ at the 1/4 dose of the recommended rate, showing difference in herbicidal activities among dinitroaniline herbicides. All the herbicides except for pendimethalin had the lower herbicidal activity in sandy soil than that of clay-loam soil. Benefin, beslogine, prodiamine, oryzalin, bensulide and siduron persisted in the soil for about 50 days, but pendimethalin persisted in the soil for about 35 days, and trifluralin and ethalfluralin for about 25 days. Ethalfluralin, oryzalin and bensulide were the most mobile(downward movement) of the 9 herbicides studied. Less mobility was observed in the turfgrass condition than that of the bare soil. Beslogine bensulide prodiamine and benefin had no injury effect on bentgrass(Agrastis atolonifera L., penncross creeping bent grass). However, herbicides like oryzalin, trifluralin and pendimethalin reduced the dry weight of bentgrass by 12%, 30% and 40%, respectively. No significant difference in distribution of pendimethalin and benefin into inner part of leaves, surface and wax layer of bentgrass was observed, and thus it seems that different phytotoxic effect between pendimethalin and benefin may be attributed to different metabolism and mode of action.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.355-363
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• 2015

The present work quantified the growth of young biofilm in a model distribution system that was fed with chlorinated drinking water at a hydraulic retention time of 2 h. Bacterial biofilms grew on the surface of polyvinyl chloride (PVC) slides at a specific growth rate of $0.14{\pm}0.09day^{-1}$ for total bacteria and $0.16{\pm}0.08day^{-1}$ for heterotrophic bacteria, reaching $3.1{\times}10^4cells/cm^2$ and $6.6{\times}10^3CFU/cm^2$ after 10 days, respectively. The specific growth rates of biofilm-forming bacteria were found to be much higher than those of bulk-phase bacteria, suggesting that biofilm bacteria account for a major part of the bacterial production in this model system. Biofilm isolates exhibited characteristic kinetic properties, as determined by ${\mu}_{max}$ and $K_S$ values using the Monod model, in a defined growth medium containing various amounts of acetate. The lowest ${\mu}_{max}$ value was observed in bacterial species belonging to the genus Methylobacterium, and their slow growth seemed to confer high resistance to chlorine treatment (0.5 mg/L for 10 min). $K_S$ values (inversely related to substrate affinity) of Sphingomonas were two orders of magnitude lower for acetate carbon than those of other isolates. The Sphingomonas isolates may have obligate-oligotrophic characteristics, since the lower $K_S$ values allow them to thrive under nutrient-deficient conditions. These results provide a better understanding and control of multi-species bacterial biofilms that develop within days in a drinking water distribution system.

• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.83-94
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• 1999

The purpose of this study was to evaluate the changes of cancellous and cortical bone and the effect of estrogen in ovariectomized rats. Fifty female rats, 250gm in body weight, were divided into three groups : ovariectomized group(OVE), ovariectomized and estrogen-injected group(OVE-EST), and sham operated and estrogen-injected group(EST). Bilateral ovariectomy was performed at the onset of the experiment. In OVE-EST group and EST group, estrogen was injected $50{\mu}g/kg$ B.W. every other days from 3 weeks after surgery to sacrifice. Each five rats were sacrificed after 5, 6, 7 weeks. One side of mandibular body was radiographed with a soft x-ray apparatus(Hitex Co., Ltd., Japan). Thereafter the obtained microradiographs were used for the morphometric analysis using a Image analyzer. The morphometric analysis was perforrmed for parameters such as total bone area, cortex bone area and medullary bone area. The other side of the mandibular bone was decalcified and embedded in paraffin as using a general method. The specimens were sectioned and stained with Mallory's anilline blue and observed light microscopically. The results were as follows. 1 In all groups, the proportion of cortex to total bone area was not significantly different. 2. In ovariectomized(OVE) group, the proportion of marrow cavity to medullary bone area increased significantly from 5 to 7 weeks(p<0.05). In ovariectomized and estrogen-injected(OVE-EST) group, it decreased significantly at 7 weeks, and in estrogen-injected(EST) group, it decreased significantly from 6 weeks(p<0.05). 3. Microradiogram and histopathologic findings revealed that marrow cavity was enlarged and osteoclasts were observed around irregular bone surface in OVE group. In OVE-EST group, the size of marrow cavity at 7 weeks was similar to that of control group. In EST group, as dense trabecular bone increased from 5 to 7 weeks, marrow cavity decreased.

• Journal of Life Science
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• v.20 no.8
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• pp.1254-1260
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• 2010

Microorganisms near the plant rhizosphere usually inhabit the surface or the inside of the plant roots and have a direct effect on plant growth by secreting plant growth promoters or antagonistic materials which protect the root zone system from various pathogens. This study was carried out to identify and isolate the antagonistic materials after isolation of microorganisms showing high antagonistic activities, in hopes of contributing to the development of sustainable agriculture and the preservation of agricultural environments. A number of antagonistic bacteria were isolated from paddy soil. Among isolates, RRj 228 showed plant growth promotion and antagonistic activity. RRj 228 was identified as Pseudomonas sp. according to the results of physiological properties and genetic methods. On the basis of the results of anti-fungal spectrum against several pathogens by RRj 228, the antagonistic effect of the isolate against Botrytis cinerea, Pythium ultimum, Phytopthola capsici, and Rhizoctonia solani, especially against red-pepper anthracnose caused by Colletotrichum acutatum, was remarkable. The experiment evaluating the biological control effect by RRj 228 revealed that the $ED_{50}$ value by the RRj 228 culture against C. acutatum, R. solani and P. ultimum were 0.14 mg/ml, 0.16 mg/ml and 0.29 mg/ml, respectively. An antagonistic substance was isolated and purified by several chromatographies from the RRj 228 culture. The $^1H$ and $^{13}C$ assignment of the antagonistic substance was achieved from two-dimensional $^1H-^1H$ COSY, HMQC, and HMBC. Finally, the antagonistic substance was identified as Phenazine-1-carboxylic acid ($C_{13}H_8N_2O_2$, M.W.=224).

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.4
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• pp.446-453
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• 2020

The purpose of this study was to evaluate the effect of Indocyanine Green (ICG) and near-infrared (NIR) diode laser on Streptococcus mutans biofilms depending on ICG concentrations. S. mutans biofilms were formed on a Hydroxyapatite disk, and 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL ICG solutions dissolved in sterile distilled water and a NIR diode laser having a power of 300 mW and a wavelength of 808 nm were applied to the biofilms. The temperature changes of the biofilm surface according to the concentrations of the ICG solution were measured using a 1-channel thermocouple thermometer. Compared to the control group, in the groups with only the 3.0, 4.0, 5.0 mg/mL ICG solution application, and in the groups with the 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL ICG solution application and light irradiation, a statistically significant decrease in the bacterial counts were observed. The temperature increase according to the concentration of the ICG solutions was 9.53℃, 10.43℃, 11.40℃, 12.10℃, 12.67℃, and 13.63℃ in ICG solutions of 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 mg/mL respectively. This study presents the potential for clinical application of ICG and NIR diode lasers as a new method for preventing dental caries.

• Journal of Gastric Cancer
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• v.6 no.2
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• pp.109-113
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• 2006

Purpose: Various minimally invasive surgical techniques, such as an endoscopic mucosal resection and a laparoscopic gastrectomy, are becoming common practice for some cases of early gastric cancer (EGC) defined in terms of the depth of invasion being limited to the mucosa or submucosa. However, there are rare cases of early gastric cancer with massive lymph-node metastasis. Materials and Methods: From 6 university hospitals of Korea, 2,772 EGC cases were resected during the various period of analysis (1,432 cases of mucosal cancer and 1,340 of submucosal cancer). Results: As control data, we used the data from a single institute, CHA University Hospital. There were nine cases of early gastric cancer (9/2,772, 0.32%) with N3 lymph node metastasis defined by more than 15 lymph nodes being metastasized according to the UICC-TNM classification (pT1N3, stage IV). Two cases were mucosal cancer (2/1,432, 0.1 4%), and seven cases were submucosal cancer (7/1,340, 0.52%). Metastasized lymph nodes varied in number from 18 to 52. There were three male and six female patients with a mean age of 57. This is a totally reversed sex ratio compared to the usual gastric cancer or EGC. Among the total of 9 EGC patients, there were 5 who had superficial spreading carcinomas with surface areas larger than $25\;cm^2$. This is a significantly higher proportion compared to the general EGC population. When we compared the tumor size according to the LN status, the N3 group was definitely larger than the other groups. 78% of the pT1N3 cases showed lymphatic invasion, which is very high compared to the 4.7% in general EGC cases. Among the 9 cases, 6 patients had too short a follow-up period to evaluate the correct prognosis, but there was one patient with a non-curative resection and two patients with early recurrence. Although the sample size is small and the follow-up period is short, we can expect a very poor prognosis when we consider the common prognosis of EGC that is widely known and accepted. Conclusion: From these results, we can a conclude that the risk factors for pT1N3 gastric cancer are female patients, submucosal invasion, larger tumor size, and lymphatic invasion. However rare, the existence of pT1N3 gastric cancer needs to be taken into consideration, especially during the diagnosis. Furthermore, minimally invasive treatment for EGC needs to be chosen with great precaution. Since the prognosis of pT1N3 gastric cancer is expected to be poor, aggressive adjuvant chemotherapy may be necessary. (J Korean Gastric Cancer Assoc 2006;6:109-113)

• Journal of dental hygiene science
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• v.17 no.4
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• pp.283-289
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• 2017

The water discharged from dental unit waterlines (DUWLs) is heavily contaminated with bacteria. The development of efficient disinfectants is required to maintain good quality DUWL water. The purpose of this study was to establish a DUWL biofilm model using well-plates to confirm the effectiveness of disinfectants in the laboratory. Bacteria were obtained from the water discharged from DUWLs and incubated in R2A liquid medium for 10 days. The bacterial solution cultured for 10 days was made into stock and these stocks were incubated in R2A broth and batch mode for 5 days. Batch-cultured bacterial culture solution and polyurethane tubing sections were incubated in 12-well plates for 4 days. Biofilm accumulation was confirmed through plating on R2A solid medium. In addition, the thickness of the biofilm and the shape and distribution of the constituent bacteria were confirmed using confocal laser microscopy and scanning electron microscopy. The average accumulation of the cultured biofilm over 4 days amounted to $1.15{\times}10^7CFU/cm^2$. The biofilm was widely distributed on the inner surface of the polyurethane tubing and consisted of cocci, short-length rods and medium-length rods. The biofilm thickness ranged from $2{\mu}m$ to $7{\mu}m$. The DUWL biofilm model produced in this study can be used to develop disinfectants and study DUWL biofilm-forming bacteria.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.484-492
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• 2012

The present study aimed to investigate the effect of static magnetic field (SMF) on the growth and physiological characteristics of common indoor plant species. Five foliage plant species, Spathiphyllum spp., Ardisia pusilla DC., Syngonium podophyllum, Peperomia pereskiifolia, and Pilea cadierei were potted into plastic pot equipped with round type anisotropic sintered NdFeB permanent magnet inside the pot. The surface magnetic flux density of each magnet was 3,500 G. After 6 months of growth period, the biomass accumulations of Spathiphyllum, A. pusilla, and P. cadierei under SMF were statistically higher than those of controls. Tissue water content also increased under the influence of SMF in most species. The photosynthetic rate of Spathiphyllum under SMF significantly increased but other species showed no significant difference compared with control. Although there was no significant increase in the photosynthetic rates of A. pusilla, and P. cadierei, they showed remarkable increase in total fresh weight under SMF. This suggests that the demand of assimilates for normal metabolism could be decreased under magnetic influence and thereby biomass accumulation could be more favored. But this is not always true for all plant species because P. pereskiifolia in this experiment, showed no changes in both photosynthetic rate and biomass accumulation. Leaf nitrogen and chlorophyll contents were enhanced significantly in most plant species under influence of SMF. Chlorophyll a/b ratio also increased by SMF. Although there might be a limitation depending on plant species, these results suggest that long-term exposure to SMF might allow plant to have an enhanced acclimation capacity against environmental fluctuations and optimal application of SMF could increase the practical use of indoor plants such as an attempt to improve indoor air quality.